Abstract:To improve algorithm versatility and picking efficiency, recognizing more kinds of fruits or vegetables and planning picking sequence for fruit clusters in visual field have become hotspots and trends of harvesting robot research. Primates can find objects and shift attention through visual selective attention mechanism, which has similarities with harvesting robots to recognize targets and to plan picking sequence. Hence, by adopting the idea and technology of bionics, a new visual selective attentionbased method was proposed for fruit cluster recognition and picking sequence planning. According to Itti visual attention computational model, this algorithm changed computing process for color feature maps, and improved feature integration method for building color conspicuity map and saliency map by introducing priori knowledge about fruits and vegetables. Using the reference of the biological neural network competition mechanism called WinnerTakeAll and artificial expertise from professional picking operators, distance, area and saliency were adopted to design the weighted preferential picking sequence strategy for fruit clusters. The experimental results showed that the proposed method in this paper achieved recognition of more than 23 kinds of familiar fruits and vegetables. Recognition correctness was higher than 93.36%. In addition, the results of picking sequence planning showed that its planning way was consistent with artificial expertise from manual picking operation.

Abstract:CFD simulations have been widely used in the study of precooling process of fresh fruits and vegetables. This work established a quasi real threedimensional model of Fuji apples, by comparing the wall shear stress, drag coefficient, separation angle and recirculation length of an apple with those of an equaldiameter sphere over a large Reynolds number range (10~30000), and whether an apple can be directly replaced by an equaldiameter sphere in the study of CFD models was verifed. Moreover, to achieve the optimal CFD model of contact points between apple and apple (or the wall of boxes) and fully consider heat transferring by contact among apples, two apples contacting with each other were studied. From the accuracy of simulation results of the drag coefficient and temperature distribution along a line from the center of an apple to the center of another apple, the optimal size range of four different ways of the contact point modifications (e.g., reduction, expansion, smoothing, bridge) for different Reynolds number range was determined. The results showed that an apple can be replaced by an equaldiameter sphere in academic research, and the maximum relative deviation was about 15% for all the physical parameters in the whole range of Reynolds number; the accuracy of bridge methods was the best in four different ways of the contact point modifications. The predicted results were consistent with the measured results by comparing simulation results with those of experiments, and the maximum rootmeansquare error and average relative error for produce temperature were 1.514℃ and 21.07%, respectively.

Abstract:Due to interference of external environments and monitoring systems, the acquired images of agricultural products are degraded by noises. The noises affect quality testing of agricultural products. This paper researched the denoising of tomato images based on anisotropic diffusion model. First, by analyzing anisotropic diffusion process of Perona-Malik (P-M) model, a new method of calculating gradient threshold was proposed. It introduced local variances of images to the 2norm method. As a result, the new method distinguished texture details and achieved dynamic selection of gradient thresholds. Second, structural similarity image measurement (SSIM) was selected as the stopping criterion, which made selection of diffusion iterations adaptive. These two steps together formed an anisotropic dynamic diffusion model for texture preserving denoising of tomato images. Finally, two groups of comparison tests were taken under different noise standard deviations of 5, 10, 15, 20, 25, and 30. The first group of comparison test was performed among the SSIM criterion, minimum mean squared error criterion，SNR criterion and decorrelation criterion. Results of the first group showed that using SSIM as iterative stopping criteria was effective and stable. The second group of comparison test was performed among the proposed model, the conventional P-M model, and the 2norm model. From visual effect, images denoised by the proposed model had more and clearer texture details. And objective evaluation of the denoised image quality was achieved by using the peak signal to noise ratio (PSNR) and gradient magnitude similarity deviation (GMSD). Compared with P-M model and 2norm model, average PSNR of images denoised by the proposed model was the highest and average GMSD of images denoised by the proposed model was reduced by 15.5% and 19.1% respectively. It demonstrated images denoised by the proposed model had lower residual noises and greater similarity to original images. In conclusion, the proposed model can remove noises while maintaining texture details, which can contribute to subsequent quality testing of agricultural products.

Abstract:Because of the extensive flexibility and accuracy, visual navigation technology has been widely used in the field of agriculture intelligent navigation, and many effective machine vision navigation application cases were developed. But under the condition of heavy fog, visual navigation precision is greatly decreased and the processing time in the front image is largely increased, which due to unable to obtain clear front image recently. If the front image interference by the fog is bigger, and image enhancement and recovery effect is not obvious, then it will cause navigation function failure, which results in unable to effectively positioning and navigation. And even it cannot work in serious. In order to solve this problem, this paper proposed an agricultural robot visual dehazing method based on image segmentation map. First of all, this paper adopted the front end image blurring vision and regional segmentation, and got the atmospheric scattering function prediction value based on the segmentation map through the image brightness information. Second, the method optimized the atmospheric scattering function estimation value based on the orientation filter, which enhanced the image edge information, and further improved the fog residual problem caused by the large sky background. Finally, the frontend image dehazing experiment was conducted based on the actual agriculture intelligent navigation platform, and the results were compared with traditional dehazing method. The results showed that the method had high precision and realtime performance. The image dehazing integrated indicators were improved by 28.9% and 29.1% respectively of two part of the video, and the time consumption was improved by 34.4% and 53.9% respectively.

Abstract:To overcome the shortages of the developed method for edge detection system based on laser rangefinder (LF), a vision based fast edge information acquiring algorithm for the LF system was proposed. Inverse perspective mapping (IPM) geometrical transform was used to remove the perspective effect on original mature wheat field. The image after IPM transformation was then processed by illumination reduction and contrast enhancement to make the difference between cut and uncut wheat field more evidently, and then transferred into grayscale image. Threshold segmentation method based on histogram was used to convert grayscale image into a binary image, so as to distinguish the cut and uncut wheat. The target points were clustered by adopting cross correlation method on each horizontal scan line in the binary image, and then Hough transform was used to detect the edge line between cut and uncut wheat. The proposed method extended the field of view of the edge detection system based on LF, and owing to the LF system the region of interest area for image processing was well restricted. The results showed an average deviation of 2.35cm, with standard deviation of 3.26. This edge detector providing satisfied performance under different conditions, was an effective edge detection method, and met the demand of recognition for navigation path in wheat harvesting.

Abstract:Maize could be used as food, animal feed, as well as industrial materials, so it has become to be the most important crop all over the world. The potential yield of maize is more than 27 mt/hm2, but the statistical data from FAO shows that farmer’s actual average yield is only one fourth of that. Precision planting is one of an effective method to increase maize yield，so as to decrease this gap. Precision planting technology has a critical effect on agricultural production and is the key to decrease cost and increase benefit for scaled farmer’s production, international machinery companies are paying more and more attention and investing a lot on invention or innovation of precision planters,so new precision planting technologies and devices, such as high speed metering systems, down force depth control units, are developing very fast, and they are widely accepted and used by individual farmers in the world. According to the various functions realized by precision planting, precision planting technologies were classified into the following categories: control technology of seed spacing uniformity, control technology of sowing depth uniformity, and intelligent integration of precision planting. On the seed spacing uniformity, technologies of single seed sowing, seed delivery and seed monitoring were elaborated. The significance of sowing depth uniformity was analyzed, and its development process was generalized. In terms of the application in intelligence, a comprehensive review of the existing research advances was presented. Finally, the development direction of precision planting technology was pointed out based on the current situation of China.

Abstract:Automatic transplanting of strawberry plug seedlings is difficult since both the plant and root lumps are much bigger and their arches must be kept outward when they are inserted into the soil and root. The inserting forces and extraction forces were tested, then a novel test of constrained extraction and the root lump rupture were designed and carried out. It was found that the inserting forces were related to speed, depth and moisture content, and the maximum inserting forces were 21.47N and 57.09N when the inserting depths were 50mm and 100mm, respectively. The maximum extraction force was 9.64N, while the constrained extraction forces reached 10.85N and 42.5N when the fingers sliding displacements were 20mm and 40mm, respectively, but big sliding displacement was not ideal for transplanting precisely. Based on physical and mechanical characteristics of strawberry plug seedlings got from the above tests, an endeffector for automatic transplanting was developed. The endeffector was composed of two grippers and one arch reversing mechanism. The gripper had two doubleneedle fingers and the inserting angle was fixed, which was helpful to realize large inserting depth in limited mechanism dimensions and avoid bruise and tearing of plants and root lumps, respectively. Taking reducing of gripper width and swing range of connecting rod as dual objectives, optimal mechanism parameters of the gripper were obtained by performing linear programming. The arch reversing mechanism transformed distance between seedlings form picking to placing and changed the arch orientation simultaneously with cooperated limit switches and electromagnets. The experiments showed that the successful rates of extraction and nondamage picking were above 93% and 90%, respectively, when the picking acceleration was no more than 020m/s2. Otherwise，larger picking acceleration may lead to root lumps broken and fingers slid out. It was found that the arch reversing mechanism was able to transform distance between seedlings and change the arch orientation precisely. Finally, all seedlings were inserted into prepunched holes successfully and depth and upright degree were qualified, and survival rate reached 100% after 10d of transplanting. This novel endeffector was proved to be able to satisfy the need of automatic transplanting of strawberry plug seedlings.

Abstract:The seedlings in greenhouse at a certain stage are transplanted from high density trays into low density flats for further growth and development. To meet the demands of transplant production in greenhouse, a simpletype automatic transplanter for plug seedlings was designed. The transplanter consisted of a manipulator, an endeffector and two conveyors. The manipulator consisting of a motor, a linear modules and a rodless cylinder, moved the endeffector to the desired working position for extracting, transferring and discharging a seedling. The conveyors were designed to move the plug tray/pot to the endeffectors working space. It was the pallettype doublerow chain transmission units. The endeffector was a pincettetype mechanism using two fingers and four pins for picking up seedlings. When the endeffector extracted seedlings from the tray cells, its two cylinder fingers push out four pickup pins to penetrate into the root soil deeply and then close making the pickup pins hold the soil of the seedlings firmly for lifting. When the endeffector released seedlings at the discharge point, its two cylinder fingers open making the pickup pins loosen the soil of the seedlings and then pulled the pickup pins back for discharging. According to the requirement of automatic transplanting of greenhouse seedlings, the electric control system was configured for the prototype. The step transmission for picking up seedlings was examined with the linear displacement sensor. The test results indicated that the transplanting rate was about 1221 seedlings per hour for the 128cell tray and 1025 seedlings per hour for the 72cell tray, respectively. The statistical analysis of onesample t test showed that there was no significant difference in the step transmissions between the testing value and the theoretical value, and the standard deviation was less than 0.5. The performance tests were further conducted to evaluate the machine efficiency. For the four locally produced vegetable seedlings, the average success ratio in picking up seedlings was up to 90.70%, and the soil damage ratio was less than 5%. The performance of transplanting was satisfactory.

Abstract:The technology of rice potted seedling transplanting can realize high yield, which has advantages of shallow planting, less damage on the seedlings, fast recovery, low and early tiller and high efficiency. Foreign rice potted seedling planting technology is not suitable in China for complicated structure and high cost problem. And there are defects for domestic transplanter with low efficiency, heavy vibration, and tossing transplantation with uncontrollable seedling perpendicularity. A new type of rice potted seedling transplanting mechanism of noncircular planetary gear train with one uncompleted noncircular gear, six noncircular gears and two transplanting arms was presented on the basis of analysis of the shortcomings of the existing rice potted seedling transplanter at home and abroad. The working principle of rice potted seedling transplanting mechanism was introduced, and the parameter optimization method of humancomputer interaction optimization was proposed. The analysis and optimization software of the transplanting mechanism was selfdeveloped and used to obtain a set of mechanism parameters for realizing better working trajectory and posture. The virtual prototype and physical prototype of the transplanting mechanism were developed to conduct virtual kinematic simulation analysis and kinematic tests with highspeed photography technology on the testbed, and the static trajectory and posture of the seedling needle of the transplanting arm were obtained. The results of the simulation analysis, bench test and theoretical analysis are almost consistent, which shows the correctness of the design method and results and the application feasibility of the transplanting mechanism.

Abstract:The furrow sowing with whole plasticfilm mulching on double ridges was widely used in the arid region of northwest China, because it could resist drought and increase production. So the mechanical plowing and filming on seedbed was an inevitable trend in farming. With aim to solve these problems about picked film, tore film and kind of holes with seedlings dislocation which were caused by the traditional film seeding machine, an electric direct insert hillseeder was designed based on the mechanism with approximate constant speed with corn whole plasticfilm mulching on double ridges. The electric direct insert hillseeder was designed by applying the rotating guide rod mechanism in series with the sine institutions and forced seeding mechanism, direct insert sowing mechanism and feeding system. And the structural parameters of its key parts were analyzed. Field experiment showed that through the mechanism with approximate constant speed to match the amplification mechanism, can control and coordinate the direct insert sowing mechanism. It achieved that the holeformer horizontal velocity component was zero in sowing period and excavating period, the planting distance could be adjusted within a certain range, and the arrangement of the soil hole and the holeformer motion trajectory were all reasonable. It adopted forced seeding mechanism to control the holeformer precision opening and rapid closing in fixedpoint, which could effectively alleviate more seed, positive hole and the hillseeder blocking under the plasticfilm. The operation machine field planting performance test related indicators were up to the relevant work quality evaluation specification requirements, and compared with the generation of prototype work performance had greater improvement and upgrading, which was to meet the requirements of agronomic techniques of dryland corn furrow seeder with whole plasticfilm mulching on double ridges.

Abstract:In order to meet the requirements of precision planting and improve the seeding quality of potato seed metering device, a kind of doublerow cross spoonbelt potato precision seed metering device was designed. The overall structure and working principle of the seed metering device were illustrated and analyzed. The optimal design of structural parameters of key components was conducted, such as the doublerow cross seeding assembly, the driving assembly and the vibration cleaningseed assembly. To improve the working performance of the metering device, obtain the best operation parameters, the quadratic general rotary unitized design was carried out with the rotational speed and the amplitude of seed metering device as the experiment factors and the seeding qualified index, the relaying seed qualified index and the missing seed qualified index as the experimental indexes. Based on experimental data, a mathematical model was built by using the Design-Expert 6.0.10 software, and the experimental factors were optimized, the best combination was achieved. Test results showed that as the rotational speed was 31.5r/min, the amplitude was 11.7mm, and the seeding qualified index was 89.92%, the improved metering device exceeded the original one by 19.9%, the relaying seed qualified index was 5.12%,and the missing seed qualified index was 4.96%. On the basis, the metering adaptability filed 〖JP3〗test was carried out, and then test results showed that the seeding performance of seed metering device to all size grades of potato seeds could meet the requirements of precision planting. The results can provide the guidance and direction for the research of potato precision seeder and its key parts.

Abstract:In order to obtain the optimum structure parameters of sine exponential curve type trenching blade, according to the equation of sine exponential curve, totally 15 types of furrowing blade were designed and test in soil bin was conducted. A central composite design method of the second order regression orthogonal was carried out with bending angle, bending radius and sliding cutting angle as experiment factors and with power consumption and stability of groove depth as response values. By using Design-Expert 8.0.6 regression analysis method and regression surface method, both single factor and interactive factor on response values were analyzed. Combined with nonlinear optimization calculation method, the structural parameters were calculated optimally. The results obtained under the conditions of soil strength was 0.29MPa, moisture content was 16.2%, in terms of significant degree, the influence factors of power consumption were bending angle, sliding cutting angle and bending radius; the influence factors of stability of groove depth were sliding cutting angle, bending angle and bending radius. The optimum parameter condition of the sine exponential curve type trenching blade after optimizing was 86.75°of bending angle，12mm of bending radius and 13.8°of sliding cutting angle. At this time, power consumption achieved theoretical optimum value of 32.32kW, stability of groove depth was 95.6%. Through verification by an experiment under optimum condition, the experiment value of power consumption was 34.27kW, stability of groove depth was 92.82%, which indicated that the experiment results and predicted results were consistent, and regression models established by the experiment were appropriate. According to comparison of trench experiment before and after parameter optimization under two different soil conditions, power consumption fell by 4.28kW and 4.23kW, respectively; groove depth stability were increased by 7.12 and 7.02 percentage points, respectively. According to comparison of existed trenching blade under two different soil conditions, power consumption fell by 7.68kW and 6.91kW, respectively; groove depth stability were increased by 14.34 and 8.34 percentage points, respectively. Research result of the article provides a theoretical basis for the sine curve type furrowing blade optimization design.

Abstract:To realize sitespecific and variablerate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presented a prototype of direct nozzle injection system (DNIS) based on which method of controlling chemical injection rate was studied. In this DNIS, a rapidreacting solenoid valve (RRV) was utilized for injecting chemicals, and it was driven by pulsewidth modulation (PWM) signal at 100Hz, adjusting the chemical injection rate with varying pulse width. A closedloop control strategy based on proportional-integral-derivative (PID) method was applied to meter and stabilize the chemical injection rate. Laboratorial experiments were conducted to assess the performance of RRV, including effect of PWM signal with startup time on pesticide injection, the power consumption of RRV, the input-output characteristics of RRV, and the time elapsed of shutting down pesticide flux completely. The performance of DNIS and PID controller on stabilizing pesticide injecting rate was also evaluated, not only output of flowmeter but also electric conductivity measuring method were employed to indicate the stabilization of pesticide. Test results showed that RRV was capable of precisely metering chemical injection rate. With PID controller, the setpoint chemical flow rate could be achieved within less than 4s, and the stability of chemical flow rate was also improved against without control strategy.

Abstract:In view of the existing peanut picking device widespreadly used, which breaking rate is high, easy winding, and blocking, based on two-stage peanut harvest, this research studied the mechanisms of picking peanut pods during picking up and threshing, and determined the optimal parameters of picking device. An axial flow peanut picking device with screw bendingtooth was designed. The screw, bendingtooth and concave sieve worked together to separate peanut pods from plant, because screw possessed pitch angle and bendingtooth possessed elevation angle, plant in a circular and axial motion along the roller and then it was eliminated from the machine, which can keep high picking rate, low breaking rate, and avoid winding and blocking. The key components were designed and calculated. Introducing the structure and principle of operation of the machine, the key components’ parameters were confirmed by deeply theoretical analysis which made up the picking mechanism that had a great influence on picking effect. The peanut variety “Huayu 30” was selected as test material, and picking gap, feed quantity and rotating speed of cylinder were selected as experimental factors. Meanwhile, the peanut picking and breaking rate were selected as experimental indexes. Through orthogonal test, the mathematical model was established between the experimental factors and indexes and studied on the response surface optimization. The working parameters of picking performance were optimized. After verification test, the conclusion was obtained that the peanut picking rate was 98.96%, the peanut breaking rate was 0.88%. When the angle between bendingtooth and roller generatrix was 33°, the angle of bendingtooth was 60°, the angle between screw and roller generatrix was 23°, which met national standard and the need of production.

Abstract:Straw debris and fermentation strains are difficult to mix together in the fertilizer manufacturing process of tomato stalks. In order to solve the problem, a vertical screw mixer was put forward and the kinetics analysis of stuffing material was carried out, and the mixing process in the mixer was analyzed numerically by DEM simulation and measurement. The results showed that the variation coefficient of mixing was less than 10% and the average power consumption was less than 0.0781kW after stirring for 3min, confirming the feasibility of the mixer in fertilizer manufacturing process of tomato stalks. The variation coefficient of mixing was decreased with the increase of pitch of blade, but the power consumption achieved the maximum at a medium pitch. With the increase of rotational speed, the variation coefficient of mixing was decreased as well, but the power consumption was increased substantially. With the increase of stuffing material height, variation coefficient of mixing and the power consumption were increased. The rank order for the effect on the variation coefficient of mixing from the most important to the least important was pitch of blade, rotational speed and stuffing material height. A mathematical model of variation coefficient of mixing with mixer geometrical variables and work parameters was built and optimized. The optimum variation coefficient for mixing was 43% when stuffing material height was 440mm, rotational speed was 30r/min and pitch of blade was 400mm. The simulated results were compared with the tested data, showing a 13.5% error between simulation and observation. This suggested that the simulated results were correct and revealed efficient mixing mechanism of the mixer. The study provides a theoretical basis for research and development of efficient and specific equipment in tomato straw and fermentation strains mixing.

Abstract:Pellet mill is one of main machines in the feed processing machinery, which occupies an important position in the feed granulation processing. In order to achieve the small quantities production need of pellet feed, the working principle and structural characteristics of the conditioner were investigated, and the main parameters of key components were determined with theoretical analysis. Accordingly, the smallscale axial multipoint gas intake conditioner was designed to be compatible with the smallscale pellet mill. The blade installation angle X1, speed of conditioner X2, and speed of feeder X3 were selected as the influence factors, and the productivity of conditioner Y1, conditioned material temperature Y2 were selected as evaluating indicators, thus the performance optimization experiments were carried out under the quadratic orthogonal rotation design. Based on the software regression analysis Design-Expert 8.0.6 and response surface analysis method, the relationship between the two influence factors and conditioning evaluating indicator was established. The results showed that X1, X2 and X3 were significantly correlated with Y1 and Y2 (P<0.01 and P<0.001, respectively). By using response surface method, the optimal aggregative index could be obtained under the condition that the blade installation angle was 381°, speed of conditioner spindle was 220.6r/min, and speed of feeder was 17.4r/min. Under this scheme, the productivity of conditioner was 12.7g/s and the material temperature after conditioning was 650℃. In this case, the conditioner had the proper productivity and the conditioned material temperature was within the scope of the technical requirements. Therefore, this conditioner has good practicability in the process of conditioning small quantities of feed raw materials; the research provides references for the design of smallscale conditioner and the parameters optimization of processing technology.

Abstract:This article is about researching the reasonable shape of the hammer feed mills separation device. We got the shape under the situation that the friction did the minimum work by calculating the frictions work when the corn granules moving inside the separation devices tube. The new separation device was made out on the basis of analysis and calculation. On the one hand, we used Fluent simulation to analyze the movement of the materials in the new separation device and the original separation device; on the other hand, we contrasted the actual transport results of the two kinds of separation devices. We got the distribution of the corn granules within the separation devices by adopting the highspeed image technology, and then we obtained the data records of the two kinds of separation devices at different turning velocities and feed quantities. Both the simulation results and the experimental results shows that the new separation device raises the transport efficiency, especially at high speed and big feed quantity. When the speed becomes higher, the transport efficiency of the original separation device gets closer to the new separation device,but the efficiency of the new separation device is still higher,the efficiency gap of the two kinds of separation devices becomes bigger again at the speed of 3500r/min; when the feed quantity becomes bigger and gets closer to the nominal rating, the efficiency gap of the two kinds of separation devices becomes bigger too,because the new separation device not only uses a new reasonable shape,but also becomes smaller than the original one. So the new separation device is effective for energy saving and consumption reducing especially at high speed and big feed quantity. This research will play an important role in energy saving and consumption reducing of feed production. It also provides a theoretical reference for the design of the separation device.

Abstract:Since the beginning of the new century, the research on the field observation and test equipment has been developed, and many important results have been achieved. To overcome the shortcomings and deficiencies of the current test equipment, improve the level of soil erosion theory, scientifically prevent and control soil erosion, developing more advanced and practical soil erosion test equipment has a great significance. For the problems of measuring accuracy of automatic sand sampler and sand collection efficiency affected by strong wind interference, a shunthedging and multistage expansion combined reducing velocity method was proposed, a shunthedging and multistage expansion combined automatic sand sampler was designed, design principle of sand separator and data wireless acquisition system were expounded, and a test and analysis on reducing velocity and separation performance of sand separator, anti strong wind interference performance and collection efficiency of sand sampler were carried out. The results showed that shunthedging and multistage expansion combined automatic sand sampler had anti strong wind interference performance and it could collect data in realtime, continuously and in a long distance wireless. The starting wind speed of free rotation was 4.23m/s, equal dynamic property was 92.94%, average sand collection efficiency was 90.42%, when wind speed was less than 18m/s, as long as soil samples which particle was greater than 55.36μm entered sand sampler, can be fully collected, power supply battery life of data wireless acquisition system was up to 31h. The signal transmission distance was 208.51m without obstacles, which can well meet the automatic observation need for soil erosion mass.

Abstract:There are few numerical models on rainfall runoff in hills-plain-wetland compound area, and the existing models can not definitely reflect the characteristics of hydrological elements spatial distribution and hydrological cycle in wetland. A numerical model on rainfall runoff was constructed in hills-plain-wetland compound area by using lattice Boltzmann method (LBM) and finite element method. When constructing the model, the compound area was divided into upstream hilly region with great topographic relief and downstream plain wetland with little topographic relief. In the upstream hilly region, spatial distribution of rainfall was calculated with the inverse distance method, soil motion model in unsaturated zone was constructed with LBM, water flow model in saturated zone was constructed with Darcy formula, numerical model of runoff was constructed with LBM, and then the numerical model of upstream rainfall runoff was constructed. Numerical model of water flow on plain wetland was constructed by using the finite element method with quadrilateral element. The entry water level boundary of plain wetland used the numerical output water level process of rainfall runoff in upper reaches, and export water level in plain wetland was achieved by calculating the export water process of watershed based on the numerical model constructed with LBM. The flow motion equation was solved with quadrilateral finite element method, which realized the seamless connection of the upstream area and the downstream area, and made the application of the model more convenient. Rainfall runoff and flow in plain area was simulated, with the Naoli river watershed as an example, and the simulation result was good, which means that the model is reliable.

Abstract:Accurate measurements of rill geometry and flow parameters provide theoretical basis for erosion processes on hillslopes. Rill width and depth are basic rill morphological characteristics. Rill flow width and depth are the foundation for calculating hydraulic and hydrodynamic parameters. A soil box (2.0m long, 0.3m wide and 0.5m deep) was subjected to a 140s movablebed scouring test under a surface inflow rate of 1L/min with slope gradients of 15° and 20°. Based on photogrammetry, point cloud and highprecision DEMs of the soil bed at different times were extracted. Measurements of rill depth and width, and rill flow depth and width were made. Variation trends of rill morphology and rill flow characteristics were analyzed and differences between photogrammetry and other measurement methods were discussed. The results showed that rill width and rill flow width could be measured directly from perpendicularly shot photographs after proportional scale calibration. Based on interpolation principal, dynamic variations of rill depth and rill flow depth could be measured. With increasing slope length, rill depth was increased while rill flow depth showed no significant trend. Rill width was increased and then decreased while rill flow width was decreased gradually along the soil bed. Increasing rates of rill widths and depths with slope gradient of 20° were 1.7 and 1.3 times as those with slope gradient of 15°. Rill flow widths in different crosssections with slope gradient of 15° were 1.7%~13.1% larger than those with slope gradient of 20°, while rill flow depths showed little difference between these two slope gradients. Rill depths and rill flow depths obtained by manual measurements with a steel ruler were 3.3%~5.1% and 91.0%~178.5% higher than those obtained by photogrammetry. Compared with traditional methods and 3D laser scanning technique, photogrammetry had speed, resolution and noncontact advantages and it can also overcome rill wall shield and prevent the occurrence of point cloud “black holes”.

Abstract:For further researching the laws of flow resistance, based on the vegetation resistance model under open channel flow, vegetation resistance models were established under six slopes (2°~12°), 〖JP2〗seven flow discharges (3.65L/min, 4.92L/min, 8.13L/min, 11.78L/min, 15.47L/min, 19.12L/min and 27.26L/min) and five vegetation coverage degrees (9.300%，6.975%，4.650%，2.325% and 0) by combined experiment with theory which was adapted to overland flow. Equivalent coverage and equivalent hydraulic radius were defined in the model based on the definition of vegetation coverage and the hydraulic radius in the open channel flow. The results showed that when the other hydraulic conditions were identical, vegetation resistance was increased with the increase of equivalent coverage and equivalent hydraulic radius, the contribution rate of equivalent coverage (0.106) was less than that (0.167) of the open channel flow; however, the contribution rates of equivalent hydraulic radius (0.5) and the drag force coefficient (0.5) were approximately identical with those of the open channel flow (both of values were 0.48), the NSE value of the model was 0.84. This article distinguished vegetation resistance and comprehensive vegetation resistance, which may provide the theoretical basis for calculation of vegetation resistance of overland flow, so as to promote the expansion hydraulics theory of the open channel in the aspect of overland flow.

Abstract:Plant growthpromoting rhizobacteria (PGPR) are beneficial native soil bacteria that colonize the rhizosphere or plant roots and regulate the functional properties of agricultural systems. One of the proposed mechanisms through which PGPR enhances plant growth is the production of plant growth regulators, especially cytokinin. However, little information is available regarding cytokininproducing PGPR inoculation on growth and water stress consistence of Lonicera japonica Thunb. seedlings. Therefore, a bacterial strain with high cytokinin production and known positive effects on plant growth was selected for use in present investigation. Crosslinked polyacrylamide is a widely studied superabsorbent polymer with segments of hydrophilic groups that can absorb and retain liquids, with the absorbed water it is difficult to remove even under pressure. In addition, because of the water absorbing properties of these macromolecules, crosslinked polyacrylamide were used in a wide range of applications in agriculture and forestry. Firstly, an inoculation experiment was conducted to determine whether crosslinked polyacrylamide could be used as carrier for PGPR by inoculating Bacillus cereus DZ1. And then, a Lonicera japonica Thunb. afforestation experiment, including five treatments, i.[KG-*3]e. PGPR (B. subtilis DZ1 inoculation alone), CLP (crosslinked polyacrylamide was applied alone), C-P (B. subtilis inoculation with CLP), CPG (gel was made of PGPR and CLP), and CK (neither B. subtilis nor CLP was applied) was conducted. The experiment was to evaluate the effect of different ways of PGPR application on Lonicera japonica Thunb. growth and microbial characteristics in rhizosphere soils. Results indicated that compared with the diluted water treatment, the number of effective viable bacteria of bean sprout juice dilution treatment in crosslinked polyacrylamide was significantly increased by 19.45%~664.05%, which meant that CLP can be used as an carrier for B. subtilis DZ1. The root exudates, namely amino acids, organic acids and total sugars in CPG treated Lonicera japonica Thunb. rhizosphere soils were significantly increased by 37.36%, 30.04% and 8.18% than those in PGPR treatment. Although B. subtilis DZ1 inoculation alone had no significant effect on microbial biomass carbon contents, the CPG treatment evidently increased microbial biomass carbon and significantly enhanced microbial respiration, showing 18.02%, 9.93%, 8.56% and 18.91% increases in microbial respiration rate over the treatments of PGPR, CLP, C-P and CK, respectively. At the same time, the metabolic quotient was reduced by the CPG treatment, demonstrating 12.74%, 7.62%, 8.02% and 14.02% decreases, respectively. Besides, the CPG treatment achieved the highest Simpson index, however the lowest Shannon and McIntosh index among all the treatments. CPG treatment had no significant effect on afforestation survival rate, it was beneficial to the shoot and root dry matter accumulation of Lonicera japonica Thunb. Compared with C-P treatment, CPG treatment increased the relative water content of Lonicera japonica Thunb. leaves by 10.34%, whereas decreased the relative electric conductance by 9.70%. As a result, the CLP-PGPR gel can alleviate the drought stress and interfere with the suppression of plant growth through regulating the micro ecological environment of Lonicera japonica Thunb. rhizosphere soil, showing a real potential to perform as a drought stress inhibitor in arid environments.

Abstract:The rhizosphere soil of facility cucumber was selected to study the effect of different biological carbon contents on changing rule of nutrient content and bacterial communities, and the regulated mechanism between nutrient content and bacterial communities during fruit growth stage. The treatments were amount of 5t, 10t, 20t, 40t and 60t biological carbon respectively added in per hectare, and the test control was the soil which did not added biological carbon in the experiment. The results showed that the content of rhizosphere soil alkali hydrolysis nitrogen, available phosphorus, available potassium, organic carbon, total nitrogen content were improved in various degree with amount of 5~60t/hm2 of biological carbon, that bacteria abundance of Proteobacteria, Actinobacteria, Firmicutes were increased but bacteria abundance of Acidobacteria, Chloroflexi were reduced with amount of 20~60t/hm2 of biological carbon, that contents of soil alkali hydrolysis nitrogen, available phosphorus and available potassium were promoted improvement by biochar regulating and improving quantity and proportion of Proteobacteria Gammaproteobacteria and Actinobacteria Actinobacteria Actinomycetales. The study also showed that by comprehensive comparison, the effect of amount of 20t/hm2 of biological carbon was better than that of other treatments, and the treatment of amount of 20t/hm2 significantly and respectively increased rhizosphere soil alkaline nitrogen content by 39.86%, available phosphorus content by 135.95%, available potassium content by 81.35%, organic carbon content by 82.89%, and total nitrogen content by 73.77%, compared with the test control in full fruiting period of cucumber.

Abstract:In this paper, a different valence states(As(Ⅴ) and As(Ⅲ)) and different concentrations (0mg/kg,10mg/kg,20mg/kg,50mg/kg,100mg/kg, 180mg/kg,280mg/kg,450mg/kg and 800mg/kg) of arsenic simulated experiment was set up to study the relationship between characteristics of chemical forms of arsenic and five soil enzyme activities(calatase, polyphenol oxidize, protease, alkaline phosphatase and invertase). Results indicated that AE-As concentration was increased and Ca-As, Fe-As and Al-As concentrations were decreased with the increase of the added amounts of both As(Ⅴ)〖JP〗 and As(Ⅲ). Meanwhile, calcium bound As(Ca-As) occupied the biggest proportion in the total. Soil enzyme activity was characterized by: two valence states of arsenic on the activity of catalase were characterized by inhibition, and inhibition rate was as high as 57.4%. As(Ⅴ) showed the obvious activity of polyphenol oxidase activation, but the As(Ⅲ) had inhibitory effect on polyphenol oxidase. As(Ⅴ) and As(Ⅲ) had effect on the activity of alkaline phosphatase of “low arsenic promotes, high arsenic suppression”. The chemical speciation of arsenic and nonlinear analysis indicated that AE - As had a significant stimulus for sucrase in As(Ⅴ) processing, and its ecological toxicity was the strongest (ED50 was 17.97mg/kg). So for calcareous soil pollution in the north, taking the exchange state As and invertase activity as the main indexes of evaluation was feasible. Through principal component analysis, when the concentration of As(Ⅴ) was up to 50mg/kg, and the concentration of As(Ⅲ) was 10mg/kg, the function of soil microbial structure was changed. The two concentrations can be used as the critical values for affecting soil microbiology properties.

Abstract:A kind of noncontact sensor based on capacitance method was designed. With the aid of the network vector analyzer, the probe of the sensor was measured in the organic solution with different dielectric constants, and the capacitance variation range of the ring probe of the sensor was determined as 7.08～22.75pF. This paper formed 11 highfrequency ceramic capacitors with different capacitances respectively connected with 102nH winding inductor in parallel into resonance circuit. Using the circuit to carry out experiment, the decision coefficient of test results and simulation results all reached 0.98. The measurement accuracy of the detection circuit met the sensor design requirements. Clay loam in Beijing area was chosen as experimental sample. The output of sensor detection unit and the corresponding measured values were carried out the polynomial fitting and linear fitting with a coefficient of determination of 0.9959. The static and dynamic performance of the system can meet the soil moisture detection requirements. The effect of temperature on the output of the sensor was analyzed. The output of the sensor was fit with the temperature, and the coefficient was 0.9879. The energy index Ka was further proposed. By the experiment, the influence ranges of longitudinal and transverse were identified as 10cm and 5cm. Finally, the comparison experiments showed that the proposed noncontact type moisture sensor was similar to that of the foreign products. It met the requirements of noncontact measurement of soil, at the same time, it had high costperformance and laid the localization foundation for the similar products.

Abstract:Solidliquid separating is an effective way to pretreat dairy manure. In order to further reduce the moisture content of separated solid and improve the efficiency of solidliquid separation, a new screw extrusion separator was designed based on the theory of changing diameter screw compression and material characteristics of cow manure. The screw extrusion separator was constituted by feed hopper, feed sleeve, separation sleeve, separation screen, screw axis, discharge device with pressadjusting spring, threephase motor and so on. Both the diameter of axis and the pitch of screw blade were changed in a linear fashion. The design equations of diameter and blade pitch were elaborated. The paper studied the relationship between separation performance and structure of screw axis, structure of separation screen, rotational speed of screw axis, press of discharge end. The separation performance was expressed in two main following aspects: separation efficiency and solid removal rate. An orthogonal experiment was done, which took taper of screw axis, clearance size of separation screen, rotational speed of screw axis and press of discharge end as factors. The experiment results indicated that the optimal condition for the separator was as follows: the taper of screw axis was 2.68°，the clearance size of separation screen was 1mm, the rotational speed of screw axis was 60r/min, and the press of discharge end was 3250N. Validation test showed that the separation efficiency was 746.18kg/h, the solid removal rate was 49.84% and the moisture content of separated solid was 61%. The results showed that the separator met the expected requirements and achieved running well. Compared with original separator, DN140 screw ertrusion solidliquid separators was more efficient, its solid removal rate was lower and power was higher. It would be an promising approach for pretreatment of cow manure by using the new machine.

Abstract:After coinoculation of rumen fluid with sludge, the methanogenic efficiency and anaerobic fermentation characteristics of straw which were influenced by combination of different digestate recirculation ratios and organic loading rates (OLR) at six stages, were studied in a semicontinuous reactor with solidfeeding device. The results showed that methane yield reached 768mL/(L·d) at4g/(L·d) of OLR and 1∶1 of digestate recirculation ratio. Methane production was 202mL/g (217mL/g) at this stage, which had obvious cost advantage. However, VFAs were accumulated significantly with propionate concentration being as high as 6.54g/L while ammonia nitrogen concentration reached 63251mg/L at 6g/(L·d) of OLR. Degradation degree of cellulose and hemicellulose in solid residues reached 88.81% at phase 2 whereas hydrolytic activities correlated with methanogenic efficiency. Through the analysis of three dimensional fluorescence spectrum, it was found that dissolved organic matters of tyrosinelike component, coenzyme F420 and humic acid were affected by digestate recirculation ratio and OLR. The changes of the components could directly reflect the methaneproducing activities and fermentation characteristics. Moreover, accumulation of humic acid was responsible for decrease of methanogenic activity. Therefore, proper digestate recirculation ratio and OLR were indispensable to longterm stable operation of biogas engineering from straw by avoiding the accumulation of harmful components in liquid digestate.

Abstract:Pyrolysis is an important way of biomass resources utilization. As a liquid product of biomass pyrolysis, biooil has good application prospects in future energy market. However, the problems of low calorific value, high viscosity, high moisture content, high corrosiveness, and poor stability problem exist until now, which constrain further application of biooil. At present, many scholars at home and abroad focus on staged utilization of biooil, by different separation methods to yield the biooils with diverse physical and chemical properties, and then by further purification to obtain the high quality of biooil. Fractional condensation can realize realtime primary separation of biooil, which can facilitate further refinement, so the field has become research focus. In order to achieve the fractional condensation of biooil，various condensation modes were studied in worldwide. Spray condensation were widely used to achieve the aim of rapid condensation because it can quickly reduce the temperature of pyrolysis gas. The tube condensation mainly depending on indirect heat transfer was used in largescale chemical production and its technology was mature, so tube condensation was applied to the research of fractional condensation. Based on the previous researches on fractional condensation unit, a fractional condensation unit using constant temperature condensation was designed, of which condensation levels and heat exchange area can be adjusted flexibly. By the independent design of multilevel condensing unit and adopting camellia seed shells as pyrolysis materials, fractional condensation tests on the pyrolysis volatiles of camellia seed shells at 500℃ were carried out, and three fractional biooil products under the condensation temperature levels of more than 165℃ and 165~120℃, below 120℃ were received. The physical and chemical characteristics of the products were analyzed, and the analysis results of the first two levelfractional products at more than 165℃, 165~120℃ showed that moisture content effectively reduced and gross calorific value was more than 23MJ/kg on average, 44% more than the calorific value obtained by conventional condensation, but kinematic viscosity was not improved. With condensation temperature dropped, kinematic viscosity had significant reduction in each group of biooil and pH value was slightly rose. Combining the thermal analysis curves with comprehensive combustion characteristic index to analyze combustion characteristics of biooil, the results showed that biooils of primary separation obtained by fractional condensation had obvious differences, and YY2 demonstrated the best combustion performance. In conclusion, realtime primary separation of pyrolysis volatiles generally was achieved by dependently designed fractional condensation and the characteristics of each stage’s product were varied. The device designed can provide a reference for design of fractional condensation of pyrolysis volatiles and lay a theoretical foundation for the further application of fractional biooil.

Abstract:A method of texture feature extraction based on the a* components of L* a* b* color space model was proposed to recognize wizened red jujube from the mix of wizened red jujube and full red jujube. Firstly, grayscale, R component from RGB color space model, a* component from L* a* b* color space model were selected and the gradient values with different gradient operators were calculated respectively. Then, abnormal gradient values were removed by morphological operator and logical operation. Finally, after gradient normalization, the gradient distributions exhibited different behavior for the wizened red jujube and full red jujube. Thus, a texture feature extraction method based on this property was designed, and the recognition of wizened red jujube was achieved. In the experiments, a 12channel fruits and vegetables sorting machine was used to collect 240 images of full red jujube and 202images of wizened red jujube. The experimental results showed that utilizing a* component from L* a* b* color space model can achieve better recognition rate than utilizing grayscale or R component from RGB color space model; simple gradient operator was more suitable than Sobel gradient operator in texture extraction for wizened red jujube recognition; using the normalized gradient histogram as a texture feature representation and the calculated ununiformities of gradient distribution as discriminant features, the recognition rate was over 99% and the false positive rate was 0.83%.

Abstract:In order to enhance the longterm identification accuracy and robustness of enose, a drift elimination method of electronic nose (enose) signals based on wavelet analysis was proposed. Firstly, wavelet decomposition was used to decompose the enose data contained drift and generated decomposition coefficients. Secondly, a relative deviation threshold filtering function was constructed to threshold wavelet coefficients and then the corrected wavelet coefficients were obtained. Finally, the enose signals which had less or not drift signals were obtained by reconstructing the corrected coefficients. For six kinds of discriminated white spirit samples, five groups of training set samples and corresponding test set samples which were randomly generated were carried out the drift elimination processing and signal reconstruction by the proposed method. After the integral values (INV) selected as a feature of the original/reconstructed enose signals were extracted, Fisher discriminant analysis (FDA) and BP neural network were employed to deal with these feature arrays of the five groups of data patterns. The FDA results clearly showed that the highest correct identification rate of five groups of training set and test set samples was 45% before drift eliminating and up to all 100% after drift eliminating, respectively. Meanwhile, BP neural network results also showed that the highest correct identification rate of the five group samples was 31.7% before drift eliminating, and the correct identification rate was up to 98.3% after drift eliminating. The two kinds of identification results illustrated the proposed method was very effective and robust for white spirit samples identification. In addition, the drift elimination method also had the reference value for the identification of other food samples.

Abstract:In order to explore the feasibility of the quick nondestructive detection of citrus Huanglong disease, the hyperspectral image technique combined with least square support vector machine (LS-SVM) and partial least squares discriminate analysis (PLS-DA) were used. The hyperspectral images of the normal, the Huanglong disease of slight, moderate and serious, the lack element citrus leaves were collected in wavelength range of 380~1080nm. By using variance analysis method, the differences in content of chlorophyll, soluble sugar and starch of leaves of the normal, the Huanglong disease of slight, moderate, serious and the lack element were analyzed, and the chlorophyll, soluble sugar and starch were the indicator which could be used to discriminate Huanglong disease. The partial least squares (PLS) method was adopted to establish the mathematical model of quantitative analysis of chlorophyll, soluble sugar and starch, and root mean square error of forecast model were 7.46, 5.51, 5.88 respectively, which provided the basis for rapid detection of citrus Huanglong disease hyperspectral images. The average spectrum of hyperspectral images was extracted in interested area. The differences in absorbance at 750nm was found by analyzing five kinds of leaves of representative spectrum of the normal, the Huanglong disease of slight, moderate and serious, the lack element. The 2order derivative was used to process the sample spectrum, the baseline drift in 450~650nm and 800~1000nm band was eliminated and the effective spectral information was enlarged. Using principal component analysis (PCA) and successive projections algorithm (SPA) to screen the input variables of the model of least squares support vector machine (LS-SVM) qualitative discrimination of citrus Huanglong disease, the LS-SVM model was built for qualitative discrimination and compared with the partial least squares qualitative discriminate model (PLS-DA) at the same time. The prediction sample set which was used to evaluate the performance of model was not used to establish the model. The results showed that the accuracy of PLS-DA model of citrus Huanglong disease was higher, three leaves of lack element were misclassified as serious Huanglong disease, and the misclassification rate was 56%. The experimental results showed that the hyperspectral image technology combined with PLS-DA can achieve rapid and nondestructive detection of citrus Huanglong disease and the degree of Huanglong disease.

Abstract:Bar code and RFID have become an important means of product identification in traceability system. Rapid conversion between different identifications plays a fundamental role in traceability link seamlessly. Based on identification feature analysis of the existing traceability systems, a bidirectional transformation equipment for traceable identification labels was designed and developed, which integrated industrial controller, RFID reader module, embedded barcode code printing module and barcode scanning module. The dynamic encryption technology was developed for the RFID to barcode conversion process, and the control flow procedure of RFID to barcode conversion was constructed. The hardware was implemented with the equipment function of label identification, bidirectional conversion, label printing and state monitoring. Two groups transformation test of RFID to 2D barcode and 2D barcode to RFID was divided. The frequency of RFID tag was 13.56MHz, and QR code was used as 2D barcode. Totally 16 combinations of each group were performed in terms of different conversion quantities and contents. The result showed that the conversion success rate was 100% in the process from RFID to 2D barcode and the conversion success rate had a downward trend with the increase of quantity and content in the process from barcode to RFID. The downward trend was caused by RFID capacity limitation or section matching. In the two kinds of conversion mode, the conversion consumption time was increased with the increase of quantity and content. The conversion time was mainly consumed in reading and printing procedure. The equipment can satisfy the requirement of label tracking and information recording in identification method transformation process.

Abstract:Reasonable partition of basic farmland construction is of great significance to arable land protection and food security. Based on farmland classification data and taking Ji’an county of Jiangxi province as the study area, this study selected arable land area ratio, fragmentation index, fractal dimension index and integrate index of connectivity for comprehensive evaluation of arable land spatial layout. Then, with the method of local Morans I spatial autocorrelation, the spatial structural characteristics and agglomerate regulation of arable land quality were explored by taking the arable land use quality index as the spatial variable. Finally, by spatial superposition combination, the spatial layout planning of basic farmland construction was given. The results showed that the arable land of the study area was divided into 2062 units which were arable land with 1km×1km grid. The arable land spatial layout was classified into three grades: first grade, second grade and third grade. The local spatial autocorrelation was divided into 4 types, including HH, LL, HL and LH. The basic farmland spatial layout was divided into priority delimited type, centralized regulation type and reserved development type, whose arable land ratio were 36.26%, 22.70% and 41.04%, respectively. The priority delimited type distributed in the central, including Litian, Meitang, Denglong, Guantian towns and eastern part of the study area. The centralized regulation type mainly distributed in northern study area, including Wanfu, Tongping towns and parts of southern study area. The reserved development type distributed in northern Ji’an county and eastern Ji’an county. With considering of arable land spatial layout and spatial agglomerate regulation of arable land quality, this study can provide reference for layout planning of the basic farmland construction.

Abstract:In order to grasp the urban expansion process in different temporal sequences objectively, rapidly and accurately, DMSP/OLS data, SPOT-VGT data, Landsat ETM+ data, DEM Data and social and economic statistics data were used to rebuild the urban expansion process. Two methods were selected to extract urban areas in Huaihe River Basin (HRB), one was threshold value method, the other was support vector machine (SVM) classification method. The results of two methods were compared with urban areas extracted from Landsat ETM+data and the result of SVM classification method which accuracy above 80% was proved to be more precise both in spatial form and accuracy estimation of urban areas. The urban areas in HRB for the year 1998, 2001, 2004, 2007, 2010 and 2013 were extracted using SVM classification method. And there were four features of the extracted urban areas calculated and analyzed to understand the dynamism of urban areas in HRB, including the extended area, urbanization intensive index (UII), extended dynamic degree and spatial pattern. The extended urban areas from 2001 to 2013 of HRB approximately showed a linear growth. UII illustrated that there were still a large number of rural areas to be developed in HRB. The extended dynamic degree stated that the urban areas expanded in a medium speed. The spatial pattern and the spatial metric revealed that there was no central city in HRB and the density of cities was not very high.

Abstract:Obtaining surface spatiotemporal data rapidly, automatically and accurately is an important issue in agriculture informationization and intellectualization. Samples obtained by manual and conventional manual visual interpretation are difficult to adapt the demands of current agricultural land resources information automatic extraction. At the same time, low altitude remote sensing technology as a kind of emerging technology for earth observation in recent years, with its flexibility, high efficiency, low cost, was widely used in the investigation of all kinds of resources. If only extraction information from single phase image, regardless of the historical image data set information extraction has been completed, it will cause information waste and repeated work. Based on this, spatiotemporal data mining technology was introduced, and related knowledge transfer learning mechanism was used, a novel landuse information classification method based on knowledge transfer learning (KTLC) was proposed. Firstly, new image was segmented by improved mean shift algorithm to obtain image objects. Secondly, the vector boundary of the objects and former historical landuse thematic map were matched and nested, invariant objects were obtained through overlay analysis, and purification of invariant object was finished by spectral and spatial information threshold filtering. The historical features category knowledge of thematic map was transferred to the new image objects. Finally, current images classification mapping was completed based on decision tree, and landuse classification mapping results were completed by the KTLC and eCognition for landuse information mapping classification (EC). The experimental results showed that KTLC could obtain accuracies equivalent to EC, and also outperforms EC in terms of efficiency.

Abstract:In order to verify the availability of UAV(unmanned aerial vehicle) optical remote sensing technology in land use type and classification, Wuyuan county Tal Lake town of Hetao Irrigation Area was chosen as research area and visible images were obtained by using TEZ fixed wing UAV equipment with SONY A5100. After obtaining the visible high resolution images by using the UAV remote sensing system, they were mosaicked in the Agisoft PhotoScan software. In addition to visually extracting ground object, we also adopted object oriented which segmentation scale was 300, shape factor was 0.4, smoothness was 0.5 to divide images. On the basis of visual, according to the specificity of ground object in spectrum, shape and texture feature, we respectively established decision tree, support vector machine, Knearest neighbor classification to extract land use type. Results indicated that SVM can accurately extract characteristics of ground object, the overall accuracy was 82.20%, Kappa coefficient was 0.7659; overall accuracy and Kappa coefficient of decision tree were 74.00% and 0.6675, respectively; overall accuracy and Kappa coefficient of Knearest neighbor classification were 71.40% and 0.6107, respectively.4 In this paper, based on the support vector machine classification method combined with the decision tree model, the overall accuracy was grown up to 84.20%, Kappa coefficient reached 0.7900. But there existed the wrong situation of small trench being divided into traffic and transport. The visible UAV remote sensing technology can be used to extract the irrigated land use types, but the extraction ditches need further study.

Abstract:Accurately and timely regional maturity date of winter wheat provides an important information and reference for commanding farm machinery and optimizing the crop harvesting order. This study took main winter wheat planting area of the North China Plain as a case study. Firstly, the daily NDVI time series have been obtained through linear interpolation using time series of HJ-1 A/B CCD images from the winter wheat’s booting to filling stages, the upper envelope Savitzky-Golay (S-G) filtered method was used to reconstruct the time series of NDVI, and then the heading stage was extracted from the NDVI profile using dynamic threshold method. Then, the resulting heading date and the effective accumulated temperature model of heading-maturity stage, combining with the average daily temperature forecast data from European Centre for medium range weather forecasts (ECMWF) was used to conduct realtime dynamic prediction maturity date of winter wheat. Finally, the prediction results were validated by observed maturity date in agricultural meteorological stations, and we test the optimal starting time for maturity date through comparing four schemes with different prediction starting date. The results showed the high accuracy of prediction maturity date when we conducted the prediction ahead of 10 d. The RMSE of predicted maturity date was about 3 d. These results also showed that predicting winter wheat maturity date at the 30 m resolution was promising and can be used for operational crop maturity monitoring and forecasting in the near future.

Abstract:The development of modern technology has made hyperspectral sensors much smaller in size and lighter in weight, which can be carried by unmanned aerial vehicles (UAVs). A new type of imaging spectroradiometer based on UAV was used to acquire the hyperspectal images of cotton field, which were used to establish the regression model aiming to predict the SPAD value of cotton leaf and make its distribution map. The results showed that in the wavelength range of 720～850nm, the reflectance had positive correlation with SPAD value. Many spectral indexes based on the hyperspectal images were significantly correlated to the SPAD value of cotton leaf on P<0.01 level. The absolute correlation coefficients of four indexes, including DR526, DR578, SDy and Db were all above 0.8. DR526, DR578, SDy and Db were used to establish the simple regression model of SPAD respectively. All the spectral indexes whose absolute correlation coefficients with SPAD value were above 0.7 were chosen to establish the multiple regression inversion model of SPAD using multiple stepwise regression(MSR) method and partial least squares regression(PLSR) method. According to the accuracy test, both SPAD-MSR model and SPAD-PLSR model had high accuracy to predict the SPAD value of cotton leaf. The six inversion models of SPAD were used to make the distribution map of cotton leaf SPAD value. The map using SPAD-PLSR model had the best result which was the closest to real SPAD distribution. Thus this research provides a new technology to supervise the growth information of cotton and other crops.

Abstract:In order to improve the detection performance on the increasing complex and diverse farmland information, a portable and configurable farmland information detection terminal was developed using a solution of high performed software and hardware based on the notion of universal design. An allinone framework which combines the mainstream embedded processor of ARM Cortex-A8 S5PV21 and the popular Android 4.0 operating system was adopted in this device. The key interfaces and modules include sensor interfaces of AD/232/485/USB, human-machine interaction modules of pushbutton/multi point capacitive touch screen/HD IPS LCD screen, data exchange modules of SD Card/USB/3G/WiFi/Bluetooth, dual mode positioning module of Beidou/GPS, and power supply/electric meter module. The core drivers, HAL library & JNI interfaces layer were customized or translated in the software to facilitate software development. Test and application showed that the proposed terminal was successfully configured with options of multiple sensors, such as analog/digital, current/voltage and video/image cameras, which demonstrated good capability of acquiring information on the soil and atmospheric parameters, crop images and geography, and had rich functionality of data presentation and exchange with multiple modes. The detection error of analog signal was less than 0.6695%, the download rate of 3G wireless communication was as fast as 1248Kb/s, and the maximum power consumption of the whole device was less than 3.6W. The outline dimension was 152mm×83mm×34mm, and the weight was only 330g. The detection terminal was easy in configuration, or in secondary development, and can be conveniently applied in farmland. The proposed terminal fully meets the need of farmland information acquisition in terms of comprehensiveness, high efficiency and accuracy.

Abstract:The current remote monitoring system for the diary farm environment is lack of mobility and too complicated to handle with high power consumption. Based on above, this paper developed a novel remote monitoring system for the diary farm environment based on the Ethernet and the public platform with WeChat. The new system can realize the accurate acquisition and remote realtime monitoring with respect to the environmental parameters, such as the temperature, humidity, CO2 concentration, H2S concentration, SO2 concentration, NH3 concentration, etc. Ethernet was used to transmit the collected data. The industrial configuration software, Kingview 6.55, was adopted to develop the monitoring software system for the upper computer. The database of the aforementioned system was connected with the public platform with WeChat. A WeChat client was established on the smart phone to remotely monitor the environment of the diary farm. Case studies were carried out on the simulation experiments of the laboratory and the actual operations of a dairy farm. It is shown that this novel monitoring system had high stability and reliability and good realtime performance with satisfactory monitoring effect. The data packet loss rate was lower than 0.041% in the range of 100m. This system can effectively solve the problem of realtimely and remotely monitoring the environmental information of a cow house.

Abstract:The parameters of body size and weight in sheep’s conformation appraisal can reflect its growth development, production performance and genetic characteristics. However, the present way of determining these parameters is normally by manual, e.g., the sheep has to stand on a flat place with correct posture when measuring the body size with measuring stick, tape measure etc., the sheep has to be tied up or hung up on the scales when weighting, which has the shortcomings of causing the stress reaction of the sheep. This paper was trying to develop a nonstress method for determining the sheep’s conformation parameters. A nonstress measuring system for sheeps conformation parameters based on machine vision technology was presented, including the design of the measuring device, the architecture of the monitoring controlling hardware and the software program. The common Modbus protocol and virtual instrument technology were used to build the system. Experimental results showed that the new method could ease the livestock measuring workload greatly and overcome the limitations of manual measurement, which was especially suitable for the current situations of feeding sheep in intensive and largescale way, and suitable for the trend in developing and applying the technologies of information and sensor in livestock industry. It provided a basis for improvement of the rational management and welfare production in sheep breeding since it prevented the animal’s stress reactions and anthropozoonosis, which was an ideal method in conformation parameters measurement for livestock. Furthermore, the research results can be extended to other industries, such as the pig industry, and have broad significance.

Abstract:The accurate establishment of forest sample plot plays a key role in capturing the parameters characteristics and reveals the regular variation of the forest. To quickly and precisely measure the fixed constructions and trees of sample plots, methods which used CCD super station to carry out image pair observation of measuring tape were proposed. Setting up the instruments in the observation point was determined by the GPS/RTK with the help of total station coordinate measurement and angle measurement function to accurately record the exterior orientation elements of the CCD moment photography. To determine the coordinates of other observation points, the appropriate baseline length to establish the image pair observation was selected in order to extract the relative threedimensional coordinates of the target location. The measuring tape method with the “S” type route, with a small amount of artificial repair and related coordinate system rotation transformation were carried out, to achieve the precise establishment of forest fixed sample and the diameter measurement. The experimental results showed that the proposed method can be used to achieve the establishment of fixed sample plots with fewer sites, and the DBH calculated by the photos were compared with field survey value. The average relative error was 3.9%, and the root mean square error was 1.2cm respectively. The proposed method has good application prospect in forest sample plot establishment.

Abstract:Plant leaf wilting is a frequent symptom responding to drought stress. To realize nondestructive testing of leaf wilting, wilting index LDBM was customized based on double blanket method from fractal theory. A laser scanner was used to acquire threedimensional point cloud data of plant leaf. In the experiment, zucchini, okra, gourd and pumpkin were chosen as research objects to test the index. Meanwhile, the vapor pressure deficit and photo synthetically active radiation were collected as the microenvironment parameters. The seeds were individually sown in the same pots. After the young plant grew, they were placed in a plasticcovered tunnel. The soil water content for these plants was maintained at about 30%. The point cloud data was gathered at 1 h interval between 08:00 and 18:00. The results showed that the index LDBM was capable of sensing various leaf wilting levels. Regression results showed that LDBM had a linear relationship with vapor pressure deficit and photo synthetically active radiation. And the correlation coefficients of four plants were [0.810, 0.879] and [0.712, 0.825], respectively. Furthermore, LDBM had a negative linear relationship with L2DFT, which was tested to be a reasonable wilting index in previous studies. The correlation coefficients of four plants were [0.826, 0.944]. This paper suggested a nondestructive, realtime and in situ method for monitoring plant water deficit stress.

Abstract:Conversion rubber track assembly is used for the replacement of the wheeled vehicle tire to reduce the vehicle’s ground pressure and improve its offroad performance. It is composed of a wheel system and a rubber track. In order to avoid detracking and excessive tension of the track and make the track perimeter match the wheel system, a modeling method of rubber track perimeter is developed which is based on variations in relative location of each wheel of the wheel system. In this method, the track perimeter is divided into two kinds of segments, circular arc segment that is in contact with wheels and deformation segment which does not contact with wheels. If a deformation segment does not contact with the raised obstacle, then it is a straight line, otherwise it is a circular arc. The effect of the roller wheel swing on the perimeter of the track is studied and the matching tensioning device is designed to maintain the track perimeter constant while roller wheels swing. Under multiterrain conditions, multicamera videogrammetric system is used to track feature points on each wheel of the wheel system and coordinates of feature points are collected to reconstruct the axis of each wheel, and then the track perimeter is modelled. Experimental results on a flat steel plate show that because of the uneven track bending stiffness, the modelled average perimeter of the track is 3791.62mm with standard deviation of 3.51mm, which is slightly smaller than the actual perimeter 3812mm of the track. Experimental results under multiterrain conditions are consistent with those on a flat steel plate, the standard deviations are all about 3.5mm and the average perimeters of the track are all in the range of 3787.78mm to 3794.75mm. Therefore, this modeling method of rubber track perimeter is effective, robust, free from the impact of terrain, and it also provides the basis for the design and assessment of the rubber track assembly.

Abstract:It is important that wheel surface curvature radius has an influence on the sinkage performance of rigid wheel in sandy environment. Based on wheel surface pressuresinkage experiment, dynamic experiment of soil bin bench and discrete element numerical simulation, the sinkage performance of rigid wheel moving on sand of flat, concave (wheel surface curvature radius was 80mm, 120mm, and 60mm) and convex (wheel surface curvature radius was 80mm and 120mm) surface of six different wheel surface curvature radii in three different shape and size sand particles (coarse diameter quartz sand, fine diameter quartz sand and dust volcanic ash) were analyzed. The pressuresinkage experiment showed that compared with other rigid wheel of different wheel surface curvature radius, the sinkage of rigid wheel with flat surface was the smallest on fine diameter quartz and dust volcanic ash. Compared with other sand medium, the sinkage of all wheels with flat, concave and convex surface were the smallest of all on coarse diameter quartz sand. Numerical simulation of wheel surface pressuresinkage showed that the force field distribution of sand particle under flat surface wheel was homogeneous and overflowed particles were small. Dynamic experiment of soil bin bench showed that the sinkage of concave R80 wheel was the smallest at the beginning of travelling period (the displacements were less than 50cm), then the sinkage of concave R60 wheel was the smallest at the travelling steady state (the displacements were larger than 70cm). On the dust volcanic ash, within the scope of the whole movement, the sinkage of concave R60 wheel was the smallest of all. Therefore, on the fine diameter quartz and dust volcanic ash, the larger wheel surface curvature radius of concave surface wheel, the better antisubsidence performance. In addition, dynamic discrete element simulation on fine diameter quartz sand demonstrated that stress area of concave wheel was focused on both sides of the wheel and concave structure could have an effective effect on preventing sand in lateral flowing and reducing the disturbance of sand. This research not only provided the reference frame for estimating the sinkage performance of wheels with different wheel surface curvature radius on different sand media, but also provided the vital theoretical basis for the design of wheel/tire wheel surface structure of desert or deep space exploration vehicle.

Abstract:Through control of the torque transfer among several groups of wet friction clutch to realize gear shift in traveling, powershift transmission of tractor has a series of advantages, such as the engine will not flameout when overloaded, good starting performance, reducing the vibration and shock of transmission system caused by suddenly load changes. The separation and joint timing of the gearshift clutch is the key factor that affects the shifting smoothness and operating comfort of the tractor. The dynamic properties analysis method of the shift process was studied. It introduced transmission’s output speed and output torque as indexes to evaluate the productivity and power of tractor, which made up for the deficiency of traditional shift quality indexes cannot evaluate the performance of the tractor. Based on the dynamic principle, the transmission system model of the power shift tractor was constructed. The dynamic characteristics of the shift process were analyzed to research the load and power flow of clutch. The control method and control strategy of powershift transmission’s shift quality were determined. Taking the output speed variation amplitude as index to optimize shift overlap time and contact oil pressure of the clutch. The control strategy of clutch was verified by simulation. The simulation results showed that the gearshift parameters chosen with the optimization algorithm were less affected by the change of tractor traction load, and the transmission output speed was transitioned smoothly. It can reduce the negative output torque generated, which avoided tractor deceleration or power transfer interruption during gearshifting, and improved the shift quality.

Abstract:The microscale combustor is an important part of microscale power system. Experiments on dimethyl ether/air catalytic combustion were carried out in quartz microchannels. The experiments mainly focused on the catalytic combustion and dynamic flame such as the effects of equivalence ratio Φ and inlet flow rate V on the stable combustion range, flame feature, wall temperature and the mole fraction of the exhaust gas. The experimental results showed that the stable combustion range was significantly higher after adding quartz wool in the combustors. When there was no quartz wool, the flame could be stable only under the condition of that the Φ varied from 1.2 to 1.4, and the flame was asymmetric. If Φ>1.4, the flame would oscillate and the oscillation cycle could be divided into three main stages; when Φ<1.2, there was no flame. Flame stationed at the quartz wool after adding quartz wool and the height of the flame was increased with the increase of V. The wall temperature distribution along the centerline of the wall was symmetrical and it was increased with the increase of V. Simultaneously, the location of the peak temperature was moved to the outlet of the combustor with the increase of V. The mole fraction of CO2 of the exhaust gas was first increased and then decreased with an increasing equivalence ratio Φ, and reached a maximum value 13.44% when Φ=1. The mole fractions of CO and H2 of the exhaust gas were increased with the increase of equivalence ratio Φ. When Φ<1, there was little CO and H2 in the exhaust gas. In contrast, some CO and H2 existed in the exhaust gas under the richfuel conditions.

Abstract:Since the permanent magnet synchronous motor(PMSM) has a large number of parameters and the direct analysis of parameters impact on PMSMs dynamic behaviors is inconvenient, multiparameter unified approach was proposed and all the PMSM’s dynamic behaviors can be discovered through indepth analysis of the unified parameters. PMSM equilibrium local stability condition as well as Hopf bifurcation condition and pitchfork bifurcation condition were derived through the Routh-Hurwitz criterion and the bifurcation theory respectively. Pitchfork bifurcation line together with subcritical Hopf bifurcation line divided the equilibrium parameter plane into three regions, where the equilibrium had different characteristics in different regions. Simulation showed the equilibrium bifurcation characteristics along with single parameter variation, and one pitchfork bifurcation point and two subcritical Hopf bifurcation points were found in the equilibrium bifurcation curve. The PMSM dynamic behaviors along with parameters variation were studied by phase portraits, time history map and Poincaré bifurcation 〖JP3〗diagram, and presented different mechanisms. If there was only one stable equilibrium in the parameters regions, the PMSM can work stably. If there were two stable equilibriums in the parameters regions, the initial conditions would affect PMSM operation. If there was no stable equilibrium in the parameters regions, the PMSM cannot work stably. The research of this paper can provide some references for PMSM design.

Abstract:Aiming at the contact impact problem caused by the manipulator in the course of operating, a method of determining the state of the system after contact collision is proposed based on the impulse principle and Gauss’ principle of least constraint. First of all, the dynamic model of the manipulator system is proposed based on Lagrange equation, besides the solution model of the external impulse of collision of the system under the collision is derived according to the classical collision theory and the equation involving coefficient of restitution; the velocity of collision point is decoupled from the impulse of collision, which is beneficial to the calculation. Secondly, based on the Gauss’ principle of least constraint and the state variables of the system before the contact collision, the instantaneous velocity solution equation of the manipulator system after collision is established according to the method of solving the extreme value of a multivariable function; according to the speed after the impact, it can be determined whether the angular velocity of the manipulator is fit for the permited working range. Finally, taking a planar three link manipulator as an example for collision dynamics modeling and simulation result, the size of the external impulse of collision and the change regularity of the manipulators’ angular velocities and each joint angle before and after the collision of the system are studied and analyzed，the driving moment required of each joint is given according to the change regularity of each joint angle before and after the collision. The research shows that the joint will have a rigid impact and each rod will shake at the collision instantaneous; the impulse of collision will be changed in the form of diminishing by the way of the distal joint to the proximal joint. The obtained conclusion in this paper may provide a theoretical basis for the motion control of the manipulator under the external impact.

Abstract:Considering the influence of the mechanical transmission flexibility on the servo control system and its control parameters, and the feed drive dynamic performance, the ball screw feed system state space model was firstly constructed in order to integrate to servo control system. Then, this state space model was integrated with servo control system model based on the digital module simulation method. And the correctness of this integration model was verified by experiment test. The test result showed that the error between experiment curve and the simulation curve was small, and the simulation result was 50.45Hz,-1.78dB in the first order natural frequency while the experiment result was 47.12Hz, -4.46dB in the first order natural frequency. In view of uncertainty of servo control parameter optimal value resulting from the nonlinear of cascade control and its dynamic characteristic, feed drive dynamic performance optimization was limited to some extent by the method of servo control parameter optimization choice. Hence, the neural network adaptive current and speed feed forward control design strategy was put forward. Based on this ball screw feed drive integration modeling, servo control parameter timevarying optimal selection as well as current and speed feed forward control strategy were combined to realize the 〖JP3〗ball screw feed drive dynamic response optimization. The following error decreased from 0.2526 to 0.1115, and interference peak decreased from 0.019 to 0.0070, rising time decreased from 0.1283s to 0.1075s. It can be seen that the response speed of ball screw feed drive system was faster while the following error was smaller, and the system antiinterference ability was better at the same time. The research of this paper provided the important theoretical basis and method guidance for the study of the overall dynamic performance and optimization of the ball screw feed drive system.

Abstract:A multifunctional magnetorheological (MR) damper with energy harvesting, velocity selfsensing and controlled damping force was designed, fabricated and tested. The energy harvesting and velocity selfsensing mechanism was composed of a permanent magnet array and induced coils which moved vertically. The proposed MR damper used the piston rod as the sharing component between the energy harvesting and velocity selfsensing mechanism and the MR damper part, and this shared component could isolate the magnetic field between two function areas. The mathematical model for the energy harvesting and selfsensing capability of the proposed MR damper was derived. Finite element model of the energy harvesting part was built up to address the power generating efficiency using ANSYS software. Experimental tests were carried out to address the performances of the proposed MR damper. The results showed that the damping force was ranged from 200N at the current of 0A to 750N at the current of 0.6A. The dynamic range equaled to about 3.75. The ACDC rectifier was applied on the power generating, and the results showed that 10V DC voltage output was harvested after the ACDC processing. Meanwhile, the velocity selfsensing performance was experimentally evaluated under different excitation frequencies and amplitudes. The experimental results showed a well fit curve under different excitations. In other words, the efficiency and feasibility of the velocity selfsensing capability of the MR damper were proved.

Abstract:In order to improve the dynamic response and characteristics of the highspeed onoff valve, structure parameters optimization was carried out in three different aspects: enlarging the pilot area of servo spiral mechanism, reducing the moment of inertia of the electro mechanical converter and using the variable ratio for the transmission device to increase the input torque of valve. Based on the analysis of the work principle in servo spiral mechanism, the new type of spool with slope groove was proposed. The bigger pilot area gradient and better response can be gotten while spool rotates were compared with round pilot hole in spool. The six pieces of structure with 26° angle, which located evenly in axial direction, were designed to lower the moment of inertia compared with the original three pieces with 52°. The variable ratio in transmission device was presented, which made the spool have more moment to reduce the chance of valve stucking at the beginning of valve opening. Curve of ration and moment with variable ratio were given to prove it. After that, mathematical model of the system was built to describe the working process. And the simulation was done in Matlab to get the logarithm amplitude versus frequency characteristic curve. The frequency was 240Hz while the logarithm amplitude was -3dB in curve and the better dynamic performance can be gotten with bigger pilot area gradient in spool. Finally, the experimental device was built to validate the theory analysis. The step response time with full scale was 8ms under 21MPa，and the leakage rate was 5.6L/min. The valve with the new structure worked better compared with 18ms under 28MPa in original valve.

Abstract:Coworkers and authors have put forward the concept of multidimensional parallel vibrating screen, and made prototype design and experimental analysis. However, the movement process of materials on the multidimensional vibrating screen and the problems of ideal sieve surface movement have not been solved yet. In this paper, the material movement process and the ideal screen surface movement of the multidimensional parallel vibrating screen were studied. First of all, two important indexes were imported, including the dispersion degree and layering rate, and the effect of six single degree of freedom (DOF) vibrations of screen surface on the material dispersion and layering process based on discrete element method (DEM) were analyzed, so the four single degree of freedom vibrations of screen surface were optimized which were more conducive to the material dispersion and layering process, that was three translations x, y, and z along the length, width and height of screen surface respectively, and a rotation γ around the normal of screen surface. Among them, the effects of the x and y single degree of freedom vibrations of screen surface were particularly obvious. Then according to screening efficiency and impurity rate, screening process of material on the multidimensional vibration sieve was simulated based on various vibration movement forms consisted of the four single degree of freedom vibrations selected. The results showed that three translational and one rotational 4DOF vibration form xyzγ had the best screen permeability, which was selected as the ideal screen surface movement form. Finally, according to the ideal screen surface movement, a 3T-1R parallel mechanism was designed, the prototype was developed, and the screening test was carried out on the prototype. The work of this paper provided a solid theoretical basis for the design of the multidimensional parallel vibrating screen and the selection of the optimum screening parameters.

Abstract:At present, the articulated arm coordinate measuring machine is playing more and more important role in industrial production. But due to its special structure, the small change of the joint angle can cause large measurement error. So the calibration of the angle variable error can effectively improve the measurement accuracy of the articulated arm coordinate measuring machine. In order to realize the direct calibration of the articulated arm coordinate measuring machine’s perpendicularity error, the two symmetric point method was put forward. Firstly, the mathematical model of the articulated arm coordinate measuring machine was established and the kinematics equation was obtained. Secondly, the perpendicularity error calibration principle was analyzed and the perpendicularity error calculation formula was obtained. Finally, with the help of the mechanical fixture, the experiments were carried out on the ROMER Infinite 2.0 articulated arm coordinate measuring machine. The accuracy of the calibration results was verified by the measurement experiment of the standard ball. This method can make the measuring result of the articulated arm coordinate measuring machine relative error reduce from 0.384% to 0.225%. The calibration method can improve the measurement accuracy of the articulated arm coordinate measuring machine. This research laid a good foundation for the further research of the measurement accuracy of the articulated arm coordinate measuring machine.

Abstract:In order to detect the minor defect echoes from noisy ultrasonic signals in nondestructive testing of metallic materials, a backscattering signal model of metallic materials was established. The unbiasedness of estimation of amplitudemodulated echo’s center frequency was discussed; and the defect echoes identification method based on empirical mode decomposition (EMD) and Stransform was proposed. In the first stage, the EMD was performed on the original signal and these IMFs with high frequency were removed, which realized a lowpass filter. Then a denoising method based on Stransform and OTSU was used for noise suppression of the reconstructed signal to eliminate the aliasing between useful signal and noise, yielding high SNR signal with relatively large amplitude attenuation. Finally, the Stransform was performed again on the resulting signal to mitigate the amplitudes attenuation caused by OTSUbased timefrequency spectrum denoising by means of multiplying a socalled amplitudegainfactor. With the above operations, the echoes became clear and their amplitudes were kept well. The processing result of simulation signals showed that the method can enhance signal significantly and highlight the defect echoes submerged by severe noise. And the processing results of experimental signals also showed the effectiveness of the method in noise suppression and defect identification.

Abstract:The roughness influence on flow boiling heat transfer characteristics of nanofluid refrigerant in direct metal laser sintering (DMLS) micro heat exchangers was analyzed through changing the roughness of different DMLS micro heat exchanger channels surface by using chemical polishing technology and preparing 0.01% Al2O3/R141b as working medium under the conditions of different heat fluxes 9.4 ~29.4kW/m2 and mass flow rates 184.3~432.2kg/(m2·s) in order to research the roughness of DMLS micro heat exchanger channels surface impact on flow boiling heat transfer characteristics of nanofluid refrigerant. The research results showed that roughness had a significant impact on flow boiling heat transfer of Al2O3/R141b in DMLS micro heat exchangers and heat transfer performance was weakened with the decrease of roughness, which was found that heat transfer coefficient was weakened by 22.5% when roughness was decreased by 80.4%. And the average heat transfer coefficient which the surface roughness of DMLS micro heat exchanger channels were 5.8μm, 3.2μm and 1.7μm were weakened by 7.1%, 14.1% and 22.5% compared with the surface roughness of DMLS micro heat exchanger channels was 8.7μm under the same conditions, respectively. It was also found that nanofluid refrigerant had much more contact area with the channel surface per unit length channels which degree of concave and convex surface was greater on the DMLS micro heat exchanger larger roughness surface so that it made refrigerant have more nucleate gasification density in per unit area and nucleation starting point in advance and another thing was that superheating degree was much lower, which were conducive to strengthening heat transfer effect. It verified the validity of the mathematical model and the reliability of the experimental results as the value of MAE was 9.88%, which was relative deviation between experimental results and revised LAZAREK heat transfer model.