• Volume 45,Issue 6,2014 Table of Contents
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    • >车辆与动力工程
    • Kinematic Analysis and Calculation of Automobile Inertial Parameters Measuring Device

      2014, 45(6):1-6. DOI: 10.6041/j.issn.1000-1298.2014.06.001

      Abstract (3628) HTML (0) PDF 1.16 M (3307) Comment (0) Favorites

      Abstract:A new automobile inertial parameters measuring device was designed to measure inertial parameters by using motions simulation of automobile roll, pitch, and yaw dynamics. Based on examining the structure, control strategy, and solution principle of the measuring device, the kinematic characteristics of the test device were analyzed by using multi-body dynamics method. The solution formulas based on rigid body rotation about a fixed axis were induced and the inertial parameters were calculated according to the experimental data. Since the dominating modal motion could cause vice modal motion, the solution formulas based on fixed-point rotation of rigid body considering coupled motions of the test device were established to verify the induced formulas. According to the experimental data, the inertial parameters were estimated by using nonlinear squares method. The estimated inertial parameters were compared with the calculated values and theoretical values. The analyzed results indicated that the calculation accuracy of automobile inertial parameters measuring device met the design needs.

    • Nonlinear Modeling and Parameter Optimization of Two-stage Series-connected ISD Suspension

      2014, 45(6):7-13. DOI: 10.6041/j.issn.1000-1298.2014.06.002

      Abstract (3919) HTML (0) PDF 1.10 M (2248) Comment (0) Favorites

      Abstract:Based on the impact of nonlinear factors on the actual mechanical properties of inerter, a nonlinear mechanical model with friction and elastic effect of screw was built. The mechanical property testing of inerter was carried out and the parameters of inerter nonlinear mechanical model were identified through the test data. Then, the mathematical model of two-stage series-connected ISD suspension with five degrees of freedom and nonlinear inerter was built. The optimized variables were determined through the sensitivity analysis of ISD suspension parameters. According to the performance evaluation index of ride comfort, the parameter optimization mathematic model of ISD suspension was established and the parameters were optimized by particle swarm optimization (PSO) algorithm. The optimization results indicated that under the premise the optimization met the requirements of driving safety and suspension working space, and the root mean square value of weighted seat vertical acceleration went down by 24.12%. It was concluded that the method proposed could effectively improve the vehicle ride comfort. 

    • Bilateral Control Strategy of Steer-by-wire System Using Force Control and Position Deviation Feedback

      2014, 45(6):14-19. DOI: 10.6041/j.issn.1000-1298.2014.06.003

      Abstract (3409) HTML (0) PDF 1.09 M (2224) Comment (0) Favorites

      Abstract:Since the unnatural road feel reactive torque was created by the variable steering ratio of vehicle steer-by-wire (SBW) system, a dynamic model was established to analyze the structure and dynamic characteristic of SBW system. In order to eliminate the coupling of steering angle and road feel torque, a bilateral control method called steering torque deviation and angle feedback was proposed, which referred to tele-presence technology of teleoperation robot by bilateral control method. The closed loop control strategies were described to guarantee the rapid performance and stability of SBW system by road motor and steering actuator motor. The effectiveness was experimentally verified using an experimental car. The results showed that the control strategies enhanceed the tracking accuracy of steering angle and improveed the vehicle handling.

    • Cascade Angle Optimization of Hydraulic Retarder Based on Flow Field Characteristics

      2014, 45(6):20-24,37. DOI: 10.6041/j.issn.1000-1298.2014.06.004

      Abstract (3221) HTML (0) PDF 1.50 M (2397) Comment (0) Favorites

      Abstract:In order to improve the braking torque coefficient, the numerical simulation of 3D transient multiphase flow was performed to the turbulent flow in Hydraulic Retarder. By the analysis of internal flow field characteristics, both the flow separation phenomenon in the work flow channel and the vortex generated in the chord surface went against the output of the braking torque. To solve this problem, considering correlation between the structural parameters of hydraulic retarder, numerical analysis based on multi-parameter flow field was performed, and the blade cascade parameters were optimized. The results showed that, the method through the analysis of the multi-parameter flow field to optimize blade cascade parameters was reasonable. When the blade angle and chamfer angle were optimized, the vortex and the flow separation phenomenon in the flow channel of impeller disappeared and the braking torque coefficient increased by 6%. 

    • Effect of Impacting Velocity on Spray Oil Droplet Impacting onto a Surface during Diesel Engine Cold Starting

      2014, 45(6):25-31. DOI: 10.6041/j.issn.1000-1298.2014.06.005

      Abstract (3802) HTML (0) PDF 1.45 M (1922) Comment (0) Favorites

      Abstract:In order to explore the mechanism of liquid film formed by fuel droplet impacting on surface in small-size combustor of diesel engine, a numerical model was developed using volume of fluid method including heat transfer and contact resistance and verified by experiments. The mechanism of droplet fluid and heat transfer as well as breakup during spreading were obtained according to the result analysis. The results also showed that the droplet maximum spreading factor and heat flux at impacting point were closely related to impact velocity, and the dimensionless time of maximum spreading factor and constant heat flux are uncorrelated to impacting velocity. The amount of heat transfer linearly increased with Reynolds number. The theoretical analysis model was also developed based on energy conservation equation, which showed a good agreement with numerical results. 

    • Characterization of Gasoline Jets from a Single-hole Direct Injection Injector by Means of Microscopic Magnification

      2014, 45(6):32-37. DOI: 10.6041/j.issn.1000-1298.2014.06.006

      Abstract (3279) HTML (0) PDF 1.23 M (1739) Comment (0) Favorites

      Abstract:The characteristics of the gasoline jets from a single-hole direct injection injector were investigated by means of a long-distance microscope and a high-speed digital camera at various injection pressures and backpressures. The results showed that the surface waves were formed along the surface of the gasoline jets, and developed randomly with time. Discontinued surface waves usually broke up at the places where the direction of jet changed and formed dense small droplets. With the increase of injection pressure, the wavelength of the surface wave shortened and their frequencies rose, which promoted the breakup of jets. The distance between two adjacent radial branches of a jet decreased with increasing fuel injection pressure and backpressure.

    • >农业装备与机械化工程
    • 3D Reconstruction of Agriculture and Forestry Crops

      2014, 45(6):38-46,19. DOI: 10.6041/j.issn.1000-1298.2014.06.007

      Abstract (4737) HTML (0) PDF 1.01 M (3345) Comment (0) Favorites

      Abstract:3D reconstruction of agriculture and forestry crops plays an important role in the studies on the biological characteristics of the crop, canopy light distribution and agricultural robot applications. Structures of crops are complex. Fast and accurate three-dimensional reconstruction of the crop is a challenging task. Crop 3D reconstruction methods have caused extensive concerns in the relevant field of study. This paper reviewed the methods of 3D reconstruction of agriculture and forestry crops. According to the technology and core device used, those methods are divided into four categories, rule-based method, image-based method, scan-based method and method based on 3D digitizer. According to this classification, the hardware of the various methods and applications in agriculture and forestry crop 3D reconstructions were summarized and described and the advantages and disadvantages of different methods were analyzed and compared. Finally, the development trend of the crop reconstruction was discussed. 

    • Detection of Seedcotton Mass Flow Based on Capacitance Approach

      2014, 45(6):47-52. DOI: 10.6041/j.issn.1000-1298.2014.06.008

      Abstract (3511) HTML (0) PDF 1.11 M (1796) Comment (0) Favorites

      Abstract:Mass flow measurement during the crop harvest process is one of important ways of data collecting for precision agriculture. In this research, a method for detecting seedcotton mass flow rate was proposed. The principle of the method was based on the fact that the dielectric constant of air/seedcotton mixture between two parallel plates increased with seedcotton mass flow rate. In order to decrease the influence of environmental disturbance, a differential capacitive sensor was designed to perform the seedcotton mass flow rate measurement. One kind of seedcotton named Xinluzao43 was used as sample to study the influence of cotton moisture content on the output capacitance value of mass flow sensors, and the relationship of cotton mass flow and sensor output capacitance. Experiment results showed that, the relationship among cotton moisture content, mass flow rate and capacitance value could be described by a bivariate regression model. The change of ambient temperature and breed had no significant relationship with the sensor output. The average relative error of seedcotton mass flow sensor was 5.16%. 

    • Research on Method of Global Path-planning for Mobile Robot Based on Ant-colony Algorithm

      2014, 45(6):53-57. DOI: 10.6041/j.issn.1000-1298.2014.06.009

      Abstract (4304) HTML (0) PDF 1.38 M (3090) Comment (0) Favorites

      Abstract:The global path-planning method for MR is studied based on the characteristics of ant colony algorithm. The environment information of a plane on which mobile robot (MR) works is expressed by the grid method. The main parameters used by ant colony algorithm, such as the number of ant m, arouse factor α, expected arouse factor βand information element hangover coefficients ρ, which affect the result of path planned, including the length of the path planned and the efficiency planning path, are simulated. It is found from the simulation result that the better global path can be gotten. The length of the path planned is shorter and the efficiency of planning path is higher when the parameters m,α,βand ρ are matched better. Based on the results of above simulation, the path is planned for MR, which works on two different work-plane using ant colony algorithm with the best matching parameters obtained from the simulation. The accuracy of theoretical research is verified by the global path planned for MR working under the different work-plane. 

    • Design of Portable Test System for Tensile Property of Plant Roots

      2014, 45(6):58-63. DOI: 10.6041/j.issn.1000-1298.2014.06.010

      Abstract (3295) HTML (0) PDF 1.37 M (2206) Comment (0) Favorites

      Abstract:To overcome the shortage of traditional test method for tensile property parameters of plant root system, one portable measuring system used in filed work is designed to obtain plant root system tensile property parameters. The system consists of two parts, mechanical device and electronic measuring part. The mechanical device is made up of rack, root holding mechanism and drive system. It adopts the building block design, whose parts can be disassembled quickly. The electronic measuring part is made of sensors, low power consumption MCU data acquisition system, and handheld device developed based on Android platform. It communicates with MCU data acquisition system via Bluetooth, as the terminal of operation, data input and the results display. The experiment results show that the measuring system is portable and accurate. It can get four classical tensile property parameters of root system from the measurement, maximum tensile resistance, tensile strength, modulus of elasticity for tension and ultimate strain. It can also show the stress-strain relationship curve, and inquiry historical data. This system can satisfy the requirements of measuring tensile property parameters of plant root system in the field work. 

    • Work Principle and Parameter Optimization of Rice-seedling Transplanter with Non-circular Gears

      2014, 45(6):64-69. DOI: 10.6041/j.issn.1000-1298.2014.06.011

      Abstract (3456) HTML (0) PDF 1.25 M (1955) Comment (0) Favorites

      Abstract:The working principle and structure of rice-seedling transplanter were introduced in this paper. According to the requirements of corresponding trajectory and posture of the transplanter, the transmission mechanism with non-circular gears planetary was proposed. The equations of displacement, velocity and acceleration of the mechanism were established. Also a computer-aided analytical and simulative program of the mechanism was compiled based on Visual Basic 6.0. The optimized parameters, optimized objections and main structure parameters were displayed in that software. Meanwhile, the optimized results were digitized. The influences of some important parameters on the kinematic characteristics of the mechanism were analyzed by the software. A group of preferable mechanical parameters were obtained subsequently, whose corresponding trajectory and posture could meet the demands of rice transplanting. The 3D model of the mechanism was established on the basis of the optimizing parameters, and then the virtual prototype test was done. Both of corresponding trajectory and posture met the agronomic requirements.

    • Dynamics Analysis and Test of Rotary Pick-up Mechanism for Vegetable Pot-seedling

      2014, 45(6):70-78. DOI: 10.6041/j.issn.1000-1298.2014.06.012

      Abstract (3660) HTML (0) PDF 1.29 M (2023) Comment (0) Favorites

      Abstract:An automatic rotary seedling pick-up mechanism used in vegetable pot-seedling transplanter, planetary gear train with eccentric gear and non-circular gear, is taken as the research object to build dynamics model. The dynamics sequence-solution method was used for solving the dynamics model. Then the variation law of force between the rotary angle of planetary carrier and various positions of the mechanism in a working cycle was obtained. The positions included chain, axle center of the sun gear, axle center of middle gears, axle center of planetary gears, meshing point between the sun gear and middle gear, meshing point between the middle gear and planetary gear. Physical prototype of the seedling pick-up mechanism was designed. Dynamics bench test was carried out to investigate dynamics characteristics of the physical prototype under four different rotary speeds, while correctness of dynamics model was verified.

    • Performance of Metering Device with Declined Discon Peanut Seeder

      2014, 45(6):79-84. DOI: 10.6041/j.issn.1000-1298.2014.06.013

      Abstract (3688) HTML (0) PDF 1.11 M (2138) Comment (0) Favorites

      Abstract:In order to improve the adaptability and working precision of the metering device on peanut seeder, the most widely used peanut seeder-Fenghua 5 is selected to study and a new declined disc metering device is designed according to the analysis of the peanut seed physical attributes. Based on the results of the orthogonal rotational combination experiment on the metering device test bed JPS-12, the performance of the metering device is analyzed and the regression equation is obtained between working parameters (metering disc velocity, declination angle, metering disc radius) and metering performance index (percentage of pass, percentage of rebroadcast, percentage of cavity and percentage of damage). Finally, it is concluded that the optimum metering performance can be obtained when the radius of the metering disc is 125 mm, the disc declination angle is 22°, and the metering disc velocity is 38 r/min. 

    • Design of Anti-blocking Mechanism Combined Driven Divider with Passive Residue Separating Device

      2014, 45(6):85-91,52. DOI: 10.6041/j.issn.1000-1298.2014.06.014

      Abstract (3579) HTML (0) PDF 1.56 M (1794) Comment (0) Favorites

      Abstract:An anti-blocking mechanism combined driven divider with passive residue separating device was designed, using simulation method and fields experiment to determine key parameters of the components. Based on the results of the simulations, the optimum parameters of driven divider were 1.24 speed ratio, 5 bars and 150mm diameter. The convex residue separating device with 750mm average radius had the strongest diffluent ability. Field experiments of seeding performance of 2BYJMFQC-4 maize precision no-till seeder, on which the anti-blocking mechanism combined driven divider with passive residue separating device was fixed, was conducted, and the results showed that the passing ability, the sowing quality, the sowing depth rate and the fertilization depth rate satisfied the requirements of the national standard. Above all, the anti-blocking mechanism combined driven divider with passive residue separating device was effective in solving straw blocking and ensuring the passing performance of the no-till maize planter.

    • Seed Force in Airflow Field of Vacuum Tray Precision Seeder Device during Suction Process of Seeds

      2014, 45(6):92-97,117. DOI: 10.6041/j.issn.1000-1298.2014.06.015

      Abstract (3817) HTML (0) PDF 1.34 M (2049) Comment (0) Favorites

      Abstract:Using the computer fluid dynamics software Fluent, the seed particle force in the airflow field of precision seeder device was analyzed. Selecting four factors(relative pressure, aperture of suction hole, distance of seed and suction hole, seed attitude), the seed particle force was studied through orthogonal simulation test, and the impact of precision seeder device working parameters on the particle force was analyzed. The mathematical model of seed particle force in airflow field was established, and the order of the effect factors was as following: distance of seed and suction hole, seed attitude, relative pressure, aperture of suction hole. The range of suction hole adsorption was 0.34~1.90 mm. Conducting experiment on the vacuum-vibration tray precision seeder device, the results of experiment were consistent with the theoretic analysis and show the correctness of the established model.

    • Wetting Property of Rapeseed (Brassica napus L. ) Stalk Surface

      2014, 45(6):98-103. DOI: 10.6041/j.issn.1000-1298.2014.06.016

      Abstract (3361) HTML (0) PDF 1.48 M (1610) Comment (0) Favorites

      Abstract:To obtain wetting property of rapeseed (Brassica napus L.) stalk surface, a CAM101 type contact angle tester was used to test the contact angle between rape stalk surface and twice distilled water & filtered rapeseed oil. Comparative analysis was made to the test on which rape variety, harvest date, test position and powder on rape stalk surface were introduced as factors. The results showed that the contact angle between rape stalk’s surface and twice distilled water & filtered rapeseed oil approximately increased linearly along with the increase of distance between test position and stalk root, and the powder on rape stalk surface made it a superhydrophobic surface. It was also shown that rape variety and harvest date had an uncertain influence on the contact angle between rape stalk surface and twice distilled water & filtered rapeseed oil.

    • Gate-type Spray System of High-frame Corn Spayer

      2014, 45(6):104-111. DOI: 10.6041/j.issn.1000-1298.2014.06.017

      Abstract (3161) HTML (0) PDF 1.44 M (2025) Comment (0) Favorites

      Abstract:A gate-type spray system was introduced for better control of insect pest in the corn crop grown mid latterly, due to the problem caused by coverage limitation of high-frame corn sprayer and low efficiency of hand operating knapsack sprayer. The new sprayer combined suspender spray device and horizontal spray boom, and was suitable to high-frame row span and self-propelled sprayer of the corn zone in northeast China. The structural and performance parameters of the system derived by theory and experiment methods were as follows: the spray angle of top nozzle and branch nozzle were 80° and 110° respectively, the angle between the “Y” branch boom and the vertical boom was 20°, the length of the boom was 1200 mm, the spray scale of the gate-type spray system in the vertical plane was 1150 mm. For analyzing the deposition characteristics of the gate-type spray system, a contrast test with the conventional boom sprayer was carried out on the test bed. Compared with the latter, the advantages of the gate type spray system were shown as follows: the unit area droplets deposited amount(UADDA) on the front surface of the leaves located on upper-middle positions was 12.5% higher than the latter, while the spray volume was the same. The UADDA on the back side of the leaves located middle position and the two sides of the leaves of the lower positions were significantly increased by using the suspender spray device. The combination of suspender and horizontal boom resulted in better deposition uniformity. 

    • Design and Experiment of Corn Harvester Head with Reel Star Wheel

      2014, 45(6):112-117. DOI: 10.6041/j.issn.1000-1298.2014.06.018

      Abstract (4364) HTML (0) PDF 1.10 M (2361) Comment (0) Favorites

      Abstract:In order to improve the adaptability of row spacing, a new type of corn harvester with reel star wheel harvester head was developed. The corn harvester head was composed of the star wheel, the screw roller and stalk pulling roller. The star wheel had six fingers, and the screw roller could lift tilting corn and feed the corn in the picking device. And the stalk pulling roller were designed by analyzing the conditions of maize not pushing to break and single continuous feeding. Finally the performance of the corn harvester head was tested when working along row or inclined row or vertical row in field. The results showed that the corn harvester head could work along row or inclined row or vertical row, and the adaptability of row spacing was improved largely, when the operation speed was 1.1~1.5 m/s, star wheel speed was 50 r/min, lifting import roller speed was 1300 r/min, and stalk pulling roller rotate speed was 1050 r/min. 

    • Parameter Optimization and Experiment on Archimedes Spiral Type of Gap Cutting Disc

      2014, 45(6):118-124. DOI: 10.6041/j.issn.1000-1298.2014.06.019

      Abstract (3981) HTML (0) PDF 1.16 M (2787) Comment (0) Favorites

      Abstract:No-till planter works below mulch of the surface stubble, straw and weeds, plastic mulch. The operating environment is poor and could easily lead to blockage and planting depth instability of no-till planter. In order to solve the broken stubble blockades, reduce stubble breaking resistance and improve the ditching stability and quality of ditching broken stubble, a new type Archimedes screw notch disc stubble breaking knife was designed based on the ridge tillage planter agricultural technical requirements of corn in the Northeast of China. The structural characteristics and size parameters were determined, gap number Z=11, maximum radius Rmax =215 mm, starting radius R0=175mm, corners Φ=32.72°, and the equation of motion was also established. The broken stubble knife indoor comparison tests of three discs (screw linear notched disc, disc smooth, semi-circular notch disc) proved the superiority of the screw linear gap broken stubble disc cutter. Meanwhile the quadratic regression mathematical models for screw linear notched disc blade broken stubble crop stubble resistance and disc type, weight machines, forward speed were established. Reserch achievement provided the theoretical basis for optimization design of stubble-breaking device. 

    • Simulation of Multi-fertilizers Blending Process and Optimization of Blending Cavity Structure in Nutrient Proportion of Variable Rate Fertilization

      2014, 45(6):125-132. DOI: 10.6041/j.issn.1000-1298.2014.06.020

      Abstract (3018) HTML (0) PDF 1.51 M (2005) Comment (0) Favorites

      Abstract:The blending process of granular multi-fertilizer flows in the nutrient proportion of variable rate technology (NPVRT) lacks mechanism research at present, and the blending cavity structure is the most important factor influencing blending uniformity of a variety of fertilizer. In this paper, using discrete element method, a variety of granular fertilizer, blending and seeding process based on three different blending cavity designs are simulated, and then the multi-fertilizers blending process and its uniformity characteristics are analyzed under three different structures. The computing results and mechanism analysis show that the collision wall shape of blending cavity affects rebound angle and horizontal velocity after particle collision, and both of factors affect the dispersed area of post-collision particles in the blending cavity. B type of blending cavity structure ensures optimum blending uniformity. When fertilizing flow increases, the fertilizer blending uniformity also increases accordingly.

    • Roots-soil Separating Device of Corn Stubble

      2014, 45(6):133-139. DOI: 10.6041/j.issn.1000-1298.2014.06.021

      Abstract (3376) HTML (0) PDF 1.34 M (2756) Comment (0) Favorites

      Abstract:In order to solve the problem of mechanical harvest of corn stubble, a roots-soil separating device of corn stubble was developed. It consisted of a double roller compacting mechanism and a dual flyweights-hit mechanism with flexible connection. The co-action of two mechanisms on corn roots-soil complex were compaction, rub, hit, impact and other ways to achieve the function of roots-soil separation. When the soil texture was medium loam and the soil moisture was 15%~20%, the test results showed that the average roots-soil separating rate was 98.12%, the roots-soil separating loss rate was 0.92% and the average efficiency reached 2.43 t/h. The device could realize the effective separation of stubble and soil. 

    • >农业水土工程
    • Water Balance Models of Typical Forestland and Farmland in Three Gorges Reservoir Area with CoupModel

      2014, 45(6):140-149,160. DOI: 10.6041/j.issn.1000-1298.2014.06.022

      Abstract (3461) HTML (0) PDF 1.26 M (1896) Comment (0) Favorites

      Abstract:Based on field measurement, the CoupModel (Coupled heat and mass transfer model for soil-plant-atmosphere system) was applied to simulate water balance in three kinds of vegetation types, including broadleaved forest (Schima superba and Lithocarpus glaber), coniferous forest (Cunninghamia lanceolata and Pinus massoniana) and farmland (Zea mays) in Three Gorges Reservoir Area of China. The results showed that the simulated values of soil moisture were fairly consistent with measured ones and the determination coefficient ( R2 ) were 0.80 to 0.91. Evapotranspiration was main output of water balance with the percentage up to 61%, and the figures were ranked as follows: broad-leaved forest (720 mm/a)>coniferous forest (700 mm/a) > farmland (601 mm/a). Annual simulated deep percolation decreased by 60 mm for broad-leaved forest and 47 mm for coniferous forest compared with that for farmland (452 mm/a), and it was even greater in wet year. For broad-leaved forestland, water consumption was more than income during the experimental period, which was the main reason causing soil water deficit. The water balance of farmland was characterized by moisture surplus, while spring and autumn drought occurred in forestlands. There was obvious difference between forestland and farmland for water conditions. Model results indicated that the vegetation species significantly influenced the magnitude of water balance components, which called for further attention to the selection of tree-species when planning future afforestation projects. Forest tending should also be applied scientifically during the practice of vegetation restoration. 

    • Effects of Different Water Treatment on Yield and Water Use of Transplanted Cotton Following Wheat Harvest

      2014, 45(6):150-160. DOI: 10.6041/j.issn.1000-1298.2014.06.023

      Abstract (3575) HTML (0) PDF 1.08 M (1757) Comment (0) Favorites

      Abstract:Water regulation has important influence on intransplanted cotton following wheat harvest. To investigate a suitable irrigation schedule of intransplanted cotton following wheat harvest, an experiment was conducted to study the effects of different water treatments on the water consumption, seed yield, water use efficiency and quality of intransplanted cotton following wheat harvest. Three irrigation level 45%~50%, 60%~65% and 75%~80% FC were set as lower limit of soil moisture for plot experiment under a rainproof canopy at squaring stage and blooming-boll forming stage, respectively. 80%~100% FC (T7), 60%~80% FC (T8), 50%~90% FC (T9) and 40%~60% FC (T10) were set for pipe experiment from seeding stage to boll opening stage, respectively. Five irrigation quota treatments, 1.6 (T11), 1.3 (T12), 1.0 (T13), 0.7 (T14) and 0.4 (T15) times of ETp(ETp was the accumulated of 20 cm pan evaporation during twice of the irrigation interval), were set for pot experiment and the irrigation time of each treatment was consistent with a cycle of 4~10 d, 3~7 d, 2~5 d and 4~10 d at seeding stage, squaring stage, blooming-boll forming stage and boll opening stage, respectively. The results were shown as follows, for plot experiment, seed yield, number of bolls per plant and single boll weight were maximum under T2, and the difference of seed yield was insignificant compared to T4, while WUE and IWUE decreased by 23.93% and 34.01%, respectively. For pipe experiment, the numbers of bolls per plant and seed yield were maximal under T7, where the seed yield decreased by 3.98% for T8 compared to CK while WUE and IWUE increased by 9.7% and 20.2%, respectively. For pot experiment, the numbers of bolls per plant and seed yield were maximal under T11, and seed yield increased by 9.7% and 30% compared to T12 and T13, respectively. This showed that moderate water stress was propitious to improve seed yield and WUE of intransplanted cotton following wheat harvest (lower limit 60%~65% FC, upper limit 80%~85% FC).

    • Spatial Variability of Soil Water Retention Curve under Fertilization Practices in Arid-highland of the Loess Plateau

      2014, 45(6):161-165,176. DOI: 10.6041/j.issn.1000-1298.2014.06.024

      Abstract (3690) HTML (0) PDF 1004.08 K (1967) Comment (0) Favorites

      Abstract:The aim of this study is to explore the spatial variability of soil moisture characteristic curve with the long term fertilization, and find out the influencing factors of that variability. Based on the long term experiment in Agricultural Ecological Experimental Station of the Loess Plateau of Chinese Academy in Changwu, the soil moisture of different suction with the long term fertilization was measured using the method of high-speed centrifuge, and the water characteristic curves were obtained by the mathematical models of Van Gennuchten. Then, the parameters such as soil moisture characteristic curves, water capacity, water supply and soil moisture availability with the multiple fertilizations were compared. The results showed that the significant variations of soil moisture characteristic curve were attributed to the changes of soil structure caused by the long-term fertilization. Chemical fertilizers (N, NP) destroyed soil structure, which reduced the soil water capacity. Organic fertilizer (M, NPM) increased the soil organic matter content, and then improved the soil structure, which increased soil water capacity. The effectiveness of the soil moisture of applying manure (M, NPM) was significantly higher than that of N, NP, CK. The water supply capacity and soil water availability were ranked as N, CK, NP, NPM, M.

    • Effects of Chemical Integrated Control Technology on Soil Water, Soil Nitrogen and Maize Yield

      2014, 45(6):166-171. DOI: 10.6041/j.issn.1000-1298.2014.06.025

      Abstract (3405) HTML (0) PDF 958.43 K (1634) Comment (0) Favorites

      Abstract:The rain-fed maize was selected as the research object. Three typical chemical agents(Polyacrylamide, Superabsorbent polymer and Fulvic acid) were combined to apply on maize production. The effects of chemical integrated control technology on the soil water, nitrogen and maize yield were researched, and the optimal chemical integrated application pattern was explored. The results indicated that the effect of three chemical agents on soil water, nitrogen and maize yield was inconsistent. PAM and SAP had significant effect on soil water and available nitrogen, while PAM, SAP and FA were combined to have effect on total nitrogen and maize yield. The largest maize yield was gotten with FA 400 times liquid and SAP 90 kg/hm2 with 270 kg/hm2 urea application, meanwhile, the available nitrogen and average soil water were 5.44 mg/kg and 0.12 respectively, which were bigger than any other experimental treatment. The higher soil water and available nitrogen were beneficial for plant to uptake water and nitrogen. Compared with the treatment without chemical agents, the maximize improvement for maize yield could be able to 21% after chemical integrated control technology application. 

    • Measurement of Soil Moisture with T-TDR Probe Based on LFF Method

      2014, 45(6):172-176. DOI: 10.6041/j.issn.1000-1298.2014.06.026

      Abstract (2921) HTML (0) PDF 1.00 M (2005) Comment (0) Favorites

      Abstract:In order to improve the accuracy of soil moisture measurement by T-TDR (Thermo-time domain reflectometry) probe because the needles of T-TDR were too short, this paper presented a new TDR waveform analysis method named LFF (Low frequency filter). The TDR waveform was transformed by fast Fourier transform algorithm, and then the spectrum of TDR wave was obtained. The LFF transformation could be realized by filtering the low frequency of TDR wave spectrum and transforming it by inverse fast Fourier transform. Four kinds of soil samples prepared by five different volumetric water content with twenty specimen, were used in the experiment. Through comparing the LFF method and the traditional WINTDR method with the oven drying method respectively, LFF method showed better results. The correlation coefficient of LFF with the oven drying method was R2=0.9835. LFF method could improve the soil moisture measurement accuracy of T-TDR and simplify the test validation procedures and improve the test efficiency.

    • Experiment on Sediment Distribution in Lateral Pipes and Clogging of Emitter

      2014, 45(6):177-182. DOI: 10.6041/j.issn.1000-1298.2014.06.027

      Abstract (4044) HTML (0) PDF 970.80 K (1869) Comment (0) Favorites

      Abstract:To clarify the influence of particle size on the distribution of lateral pipes and clogging of emitter in drip irrigation system, the experiments of short term muddy water and clogging were conducted with eight types of different particle size to investigate the distribution of sediment in different lateral pipes and emitter clogging situation. The results showed that the coefficient of siltation distribution of lateral pipes could be used to measure the nonuniform siltation distribution of sediment in different lateral pipes. The moving state of sediment in branch pipe greatly influenced the amount of sediment entered from lateral pipes. Therefore, the situation of sediment deposited in different lateral pipes could be determined by the suspension index of sediment in branch pipe. The siltation amount was more nonuniform in each lateral pipe when the suspension index was higher. The mutation happened where suspension index was 0.325. In addition, the large particles of sediment moved as the form of bed load at the bottom of lateral pipes, which directly resulted in the unexpected clogging of emitter, and mainly appeared in the first and second lateral pipe. While the flocculation of the fine particles was the main reason causing the clogging of the emitter. The research on the distribution of sediment in lateral pipes and the clogging rule of emitter in drip irrigation system was helpful to deeply understand sediment motion rule in pipe network and provided some references for searching clogging reason of emitters and reasonable arrangement of lateral pipes.

    • 3D Numerical Simulation of Internal Flow Field in Gill-piece Separation Device under Different Gill-piece Spacing

      2014, 45(6):183-189. DOI: 10.6041/j.issn.1000-1298.2014.06.028

      Abstract (3160) HTML (0) PDF 1.44 M (1687) Comment (0) Favorites

      Abstract:To study the effect of gill-piece spacing on velocity field and sediment distribution in gill-piece separation device, 3D numerical simulation based on laminar model, Eulerian model and Phase Coupled SIMPLE algorithm provided by Fluent software was conducted in simulating water-sediment flow field of different gill-piece spacing under hydrostatic condition. The velocity field and the distribution of sediment concentration were compared and analyzed according to the numerical results. It indicated that the velocity distribution was different under different gill-piece spacing. The effect on velocity flow field from sediment flow in the sediment channel and clear water flow in water channel would get greater as the gill-piece spacing became greater. When the gill-piece spacing was smaller, the precipitation effect would be better in gill-piece separation device. Taking the average velocity of sediment and clear water as the examination index and considering the characteristics of flow field, effect of water-sediment separation, and cost of making gill-piece separation device, the best gill-piece spacing was proposed as d=5 cm.

    • >农业生物环境与能源工程
    • Effect of Mineral-based Additives on Organic Matter Degradation during Pig Manure Aerobic Composting

      2014, 45(6):190-198,316. DOI: 10.6041/j.issn.1000-1298.2014.06.029

      Abstract (3445) HTML (0) PDF 1.32 M (2222) Comment (0) Favorites

      Abstract:In order to investigate the effect of mineral-based additives on organic matter degradation during composting of pig manure under aerobic condition, pig manure was mixed with corn stalk powder and the mixture was composted for 90 days after amending with mineral-based additives such as flyash, weathered brown coal, and bentonite at 2.5% addition amounts. And the organic matter degradation characteristics were evaluated by chemical analysis and FTIR methods. The results showed that the additives had no remarkable influence on composts temperature evolution. During the thermophilic phase, temperatures above 55℃ were rapidly established and continued over a week with the maximum temperatures up to 70℃ in all the composts. TOC and WSC decreased as composting progress, whereas the TOC decrease was enhanced in order of flyash, bentonite and weathered brown coal. Mineral additives improved the composts humification. Germination index of Ardisiasquamulosa presl- seeds showed a significant negative correlation with WSC, and presented significant positive correlations with PHA and DP. The organic matter of the pig manure-additive mixture was characterized by a high polymerisation degree of the humic-like substances, with a relative high proportion of humic acids in relation to fulvic acids. The FTIR analysis showed that the contents of the compounds with —OH,—CH3 and —CH2 groups decreased with time, while the contents of the compounds with —CO, —C—O—C,—COO and aromatic groups increased with time, and the organic matter degradation process could be last for 60 days during composting. The GI values increased with composting time, while the developments were significant inhibited during the initial stage when mineral-based additives were added. After 90 days composting GI values were over 0.5 indicating the maturity composts for all treatments.

    • Investigation of Bionic Coupling Blades Structure for Small Wind Turbine Wing Feathers

      2014, 45(6):193-197. DOI: 10.6041/j.issn.1000-1298.2014.06.032

      Abstract (3337) HTML (0) PDF 1.06 M (1963) Comment (0) Favorites

      Abstract:With the aim to solve the specific problem of low utilization rate of small wind turbine generator blade radial flow, in order to investigate the long eared owl wing structure, the bionic coupling technology was adopted. The wing structure of the reverse reconstruction for the long eared owl was built by 3D Scanner laser scanner system and the bionic coupling blades structure theory model was established based on the wing feathers of sequential arrangement way. Through the comparison of the baseline NACA 0015 airfoil and the bionic coupling blades structure airfoil, the lift coefficient for the bionic coupling blades structure airfoil increases with blade pitch and chord length ratio s/c decreases. When s/c=0.33, the CL value is the highest at α=16°, CL=1.26, which increases by 13.5% than baseline foil.

    • Performance of CO2 Removal from Biogas by Using Amine-based Amino Acid Salts

      2014, 45(6):199-205. DOI: 10.6041/j.issn.1000-1298.2014.06.030

      Abstract (3660) HTML (0) PDF 1.12 M (1898) Comment (0) Favorites

      Abstract:Amine based amino acid salts were investigated in this study by using a bubbling CO2 absorption and regeneration reactor to assess their CO2 absorption performance from the simulated biogas and regeneration characteristics. In addition, monoethanolamine (MEA) and piperazine (PZ) were also experimented to compare with these amine based amino acid salts. In the experiments, the typical biogas consisting of 40% CO2 and 60% CH4 was used under the ambient circumstance, while 35℃ and 75℃ were adopted to act as the absorption and regeneration temperatures of solvents, respectively. And pure CH4 was also used to act as the sweeping gas during CO2 regeneration stage. The results showed that when the equilibrium CO2 absorption and regeneration statuses were reached, the net CO2 cyclic capacities of all the four MEA-based amino acid salts were higher than MEA, and MEA-based L-ornithinate (MEAORN) with 30% weight fraction owned the highest value (about 0.733 mol/mol), which was approximate 82.43% higher than PZ with 15% weight fraction gaining the second higher CO2 cyclic capacity. Furthermore, CO2 removal costs from biogas of different absorbents were assessed and compared when considering the regeneration energy consumption and investment of absorber and desorber. Results showed that no matter the scale of CO2 absorption plant was taken into application, the CO2 removal costs of MEAORN and PZ might be less than MEA. And MEAGLY might have the potential to act as the most promising alternative to replace MEA in the large-scale biogas upgrading plants. 

    • Analysis and Characterization of Bio-oil Produced from Vacuum Pyrolysis of Rape Straw

      2014, 45(6):206-211. DOI: 10.6041/j.issn.1000-1298.2014.06.031

      Abstract (3625) HTML (0) PDF 980.75 K (1461) Comment (0) Favorites

      Abstract:Rape straw was chosen as the raw material to produce bio-oil crude (BC) in a vacuum pyrolysis system. BC was vacuum distilled into low boiling fraction (LBF) and high boiling fraction (HBF). Homogeneous aging fraction (HAF) and thick deposited fraction (TDF) were obtained after sealed storage of BC for 90 d. BC was preliminarily analyzed using gas chromatography/mass spectrometry (GC-MS). Chemical structure of samples was investigated using Fourier transform infrared spectrometry (FT-IR). Average molecular weight and distribution of all samples was studied using gel permeation chromatography (GPC). The results showed that BC contained many substances, including water, alkanes, phenols, alcohols, ketones, aldehydes, carboxylic acids, esters, aliphatic and aromatic compound, etc. Frequency shifting and variation of light transmittance from FT-IR analysis showed that the violent movement of electron on different functional groups intensified the interaction of molecular in bio oil. BC and LBF were close to monodisperse system, and HBF, HAF, and TDF were polydisperse system, whose dispersity parameters were 15.85, 7.91 and 20.86 respectively. It was necessary for BC upgrading to improve its stability.

    • >农产品加工工程
    • Quantitative Determination of Low Amino Acid Contents in Tea by Using Near-infrared Spectroscopy

      2014, 45(6):216-220. DOI: 10.6041/j.issn.1000-1298.2014.06.033

      Abstract (3911) HTML (0) PDF 1.02 M (1908) Comment (0) Favorites

      Abstract:Near-infrared spectroscopy (NIRS) was used for quantitative determination of free amino acid contents in tea samples. Two spectral preprocessing methods including continuous wavelet derivative (CWD) and standard normal variate (SNV) were used for spectral transform. Partial least squares regression (PLSR) was used for modeling. Monte Carlo uninformation variable elimination (MCUVE) and successive projections algorithm (SPA) were used for optimizing the modeling variables. It was shown that CWD-SNV method could effectively improve spectral quality, and eliminate translation error. MCUVE-SPA method could greatly improve the precision of model, and compress the modeling variables. The correlation coefficient of prediction ( Rp ) and root mean square error of prediction (RMSEP) of analytical models were optimized from 0.851 and 0.117 to 0.895 and 0.107,and modeling variables were reduced from 4148 to 18. NIRS combined with chemometrics could get a better analytical model when amino acid contents exceeded 0.1%. It can provide a fast and simple analytical procedure for the determination of low contents amino acid.

    • On-line Identification of Defect on Apples Using Lightness Correction and AdaBoost Methods

      2014, 45(6):221-226. DOI: 10.6041/j.issn.1000-1298.2014.06.034

      Abstract (3937) HTML (0) PDF 1.37 M (2270) Comment (0) Favorites

      Abstract:An algorithm was proposed to on-line identify the defects and stem-calyx on apples based on lightness correction method and AdaBoost classifier. The ‘Fuji’ apples were selected as the experiment object. First, the RGB images and NIR images of apples were acquired, and NIR images were binarized to obtain the mask images. Second, the R component images were corrected by using proposed lightness correction algorithm and the defect candidate regions were obtained by binarizing the corrected images with a single threshold. Third, every candidate region was treated as a mask, and the information of random seven pixels in the candidate region were selected as the characteristics of the selected candidate region. Finally, an AdaBoost classifier was used to classify these candidate regions by voting way, and the category of candidate region was determined according to the final voting results. For the investigated 140 samples, the results with a 95.7% overall detection rate under acquisition speed of three apples per second indicated that the proposed algorithm was effective.

    • Effects of High Hydrostatic Pressure Processing on Microbial Inactivation and Quality of Fresh-cut Pumpkin

      2014, 45(6):227-236. DOI: 10.6041/j.issn.1000-1298.2014.06.035

      Abstract (4078) HTML (0) PDF 1.00 M (1770) Comment (0) Favorites

      Abstract:The effects of high hydrostatic pressure (HHP) (150~550 MPa, 10 min) on microorganism inactivation and quality of fresh-cut pumpkin were investigated. HHP treatment with 550 MPa and 10 min was sufficient to inactivate total aerobic bacteria, molds and yeasts in fresh-cut pumpkin without significantly influencing the total soluble solid, pH value, drip loss, sucrose total phenols of fresh-cut pumpkin (P>0.05). However, the contents of vitamin C, color parameters, hardness, glucose, fructose and antioxidant activity in HHP-treated fresh-cut pumpkin were significantly decreased . Vitamin C was decreased by 18.9%. Moreover, the kind and contents of the alkenes , aldehydes, phenols and ketones in fresh-cut pumpkin were significantly variable (P<0.05) after HHP treatment, but the aroma quality of fresh-cut pumpkin was better retained. Therefore, it was concluded that the ultra high pressure technology was a very promising technology on fresh-cut pumpkin cold processing.

    • Purification of 6-gingerol from Oleoresin with Macroporous Resin

      2014, 45(6):237-241,328. DOI: 10.6041/j.issn.1000-1298.2014.06.036

      Abstract (3394) HTML (0) PDF 1.01 M (1704) Comment (0) Favorites

      Abstract:In order to separate and purify 6-gingerol from oleoresin by macroporous resin, 6 kinds of macroporous resins were chosen to carry out static and dynamic adsorption-desorption experiments. Qualitative and quantitative analysis of purification results were analyzed by HPLC-UV and GC-MS. The results showed that D101 was the optimal macroporous resin for separating and purifying 6-gingerol, the best technology parameters were as follows: sample concentration of 2 mg/mL, distilled water of 3 BV, 80% ethanol for elution velocity of 2 mL/min, elution volume of 4BV. Under these conditions, the purity of 6-gignerol enhanced from 1.54% to 71.32%.

    • Development of Seed Circulation Drying System

      2014, 45(6):242-248. DOI: 10.6041/j.issn.1000-1298.2014.06.037

      Abstract (3551) HTML (0) PDF 1.09 M (1794) Comment (0) Favorites

      Abstract:A small scaled seed circulating dryer and an induced-draft drying process system were developed by analyzing physical properties of seeds and objective potential energy of drying systems. A kind of proportional valve was designed to eliminate thermal inertia of dryer thermal (the ratio of exhaust gas to hot air) and an adaptive control system was developed base on the relationship between seed moisture and drying process by using the proportional valve. To ensure the reliability of the drying machine cleaning, a delivery flap, which could rotate 360°, was designed to clean up the dryer and realize step-less delivery. The result showed that the drying temperature was lower than the traditional drum wind dryers by 9℃, and the drying efficiency was increased at least by 20%, and no seeds were leave over after delivering.

    • Reliability of Bi-G Model for Experimental Determination of Mass Transfer Coefficient of Biological Materials

      2014, 45(6):249-253. DOI: 10.6041/j.issn.1000-1298.2014.06.038

      Abstract (3567) HTML (0) PDF 1023.71 K (1499) Comment (0) Favorites

      Abstract:In order to validate and analyze the reliability of Biot number-lag factor (Bi-G) correlation to estimate convective mass transfer coefficient and moisture diffusion coefficient of biological material under hot air drying, the drying experiment data of carrot slice is fitted by the exponential function, and the convective mass transfer coefficient and the moisture diffusion coefficient are estimated by Bi-G correlation. Then, the estimated values are used to simulate moisture change of carrot slice in the drying model, in which the internal moisture diffusion follows the Fick’s second law of diffusion, and the mass transfer between the biological medium and hot air follows the convective boundary condition. The calculated values are compared to the drying experiment data. The results show that the exponential function fitting drying experimental data well is not the sufficient condition for the Bi-G correlation to accurately estimate the convective mass transfer coefficient and the moisture diffusion coefficient. Bi-G correlation can not be used to accurately estimate the convective mass transfer coefficient and the moisture diffusion coefficient. 

    • Influence Factors of Air-temperature Increasing within Refrigerated Trucks during Door-opening State

      2014, 45(6):254-259. DOI: 10.6041/j.issn.1000-1298.2014.06.039

      Abstract (3298) HTML (0) PDF 1.39 M (1777) Comment (0) Favorites

      Abstract:The drastic changes of interior air-temperature and humidity induced by intense heat-mass exchange between inside and outside make the quality of perishable food difficult to guarantee while the door of the refrigerated truck is opened in the process of refrigerated transport. Aiming above problems, a mathematical model of interior temperature of refrigerator truck under the open-door state was established based on the theory of dynamic heat balance, and testified correspondingly through the analysis of influence of parameters on temperature. The test results showed that, when the refrigeration system turned on or off, and the door was opened in the 6min, and the initial temperature of the compartment was 0℃, the former temperature was 0.3℃ lower than the latter temperature. Similarly the former temperature was 0.7℃ lower than the latter temperature, when the refrigeration system turned on or off, and the door was opened in the 6 min, and the initial temperature of the compartment was -15℃. The former temperature was all 0.2℃ lower than the latter temperature, when comparing the speed of the evaporator outlet velocity was 4m/s and 2m /s, or the thermal conductivity of insulating materials was 0.05W/(m·K) and 0.033W/(m·K), and the door was opened in the 6min, and the initial temperature of the compartment was 0℃. Besides, the air-temperature increased more correspondingly inside refrigerated compartment in the situation of big temperature difference between interior and exterior and wider door-opening. Lastly, the interior heating rate was different according to the wind and wind direction outside of refrigerator carriage with the door opened. 

    • Cooperative Control of Flow Field and Temperature Field in Refrigerated Transport Carriage

      2014, 45(6):260-265,290. DOI: 10.6041/j.issn.1000-1298.2014.06.040

      Abstract (4066) HTML (0) PDF 2.54 M (1717) Comment (0) Favorites

      Abstract:Heat balance formula of red bayberry was developed. The air flow and temperature field heterogeneity’s properties of flow field in refrigerated transport carriage’s physical model and the distributions of flow field and temperature field in cross sections and longitudinal sections were analyzed. The wind direction of top right adiabatic gas curtain was set perpendicular to isothermal curves to control the gas curtain fan with constant speed intermittently based on coordination principle. The test data of refrigerated transport carriage showed the highest temperature in cross sections dropped from 3.8℃ to 1.67℃, the biggest standard deviation amplitude of temperature values was 0.387 in three cross sections with length direction. The results indicated that only accelerating the gas curtain fan’s speed could not improve the temperature distribution homogeneity effectively, opening the adiabatic gas curtain and adjusting the wind direction in included angle of gradient direction of isothermal curves and tangent direction of flow line based on cooperative principle could improve the temperature distribution homogeneity effectively. 

    • >农业信息化工程
    • Retrieval of Land Surface Temperature from FY3 Infrared Imageries

      2014, 45(6):266-274. DOI: 10.6041/j.issn.1000-1298.2014.06.041

      Abstract (3512) HTML (0) PDF 1.45 M (2030) Comment (0) Favorites

      Abstract:This paper focuses on the estimation of land surface temperature (LST) based on the measurements from the visible and infrared radiometer (VIRR) and the medium resolution spectral imager (MERSI) on board the second-generation polar-orbiting meteorological satellite of China (FY3). The moderate spectral resolution atmospheric transmittance algorithm and computer model (MODTRAN) were used to simulate FY3 VIRR and MERSI infrared data. The split-window algorithm was employed to build LST estimation models based on the simulated data. The LST estimation experiments were conducted in Jiangsu Province. Nine images with fewer clouds cover were acquired on January 23 and February 3 and 11, 2012. They consisted of three VIRR band 4 images, three VIRR band 5 images and three MERSI band 5 images, which were used to retrieve LST of the experimental region. LST estimation from the images acquired at the first two days was evaluated by MODIS LST products. The results showed that the combination of the VIRR 4th and 5th bands obtained higher LST estimation accuracy, compared with the combination of the VIRR 4th and MERSI 5th band. In addition, it was found that the estimated LST from VIRR 4 and 5 band images had a systematic bias (-1.664) compared with MODIS LST. The systematic bias was used to revise the LST estimation model. The revised model was validated by the images acquired at February 11. The results showed that the correlation coefficient between the estimated LST and MODIS LST was 0.877, and the RMSE was 1.33K. Compared with FY3 LST products, the estimated LST from the model was comparable to MODIS LST product.

    • Fisher Discriminant Analysis of Dendrolimus punctatus Walker Pest Levels

      2014, 45(6):275-283. DOI: 10.6041/j.issn.1000-1298.2014.06.042

      Abstract (4008) HTML (0) PDF 1.04 M (1883) Comment (0) Favorites

      Abstract:The Dendrolimus punctatus Walker is the most serious forest defoliator in China. The study of pest remote sensing prediction is helpful to the comprehensive and timely identification of possible damage regions, and can provide the technical support for the direct and indirect losses reduction. Taking Fujian Province as the study area, the Dendrolimus punctatus Walker overwintering generation was investigated in 13 monitoring stations, Sanming City, Jiangle County, Shaxian County, Nanping City, Huaan County, Yunxiao County, Nan’an City, Anxi County, Putian City, Changting County, Jianyang City, Ningde City, and Fuqing City, successively from February to May 2012. The investigation indices contained GPS coordinates, pine forests canopy spectrum, climate, terrain, stand, pest source, human environment and so on. After the analysis and extraction of these factors above, the sub-factors used to predict the Dendrolimus punctatus Walker pest levels were obtained with correlation analysis. With the help of Fisher discriminant analysis, the discriminant functions of 4 pest levels, non-damage, mild damage, moderate damage and severe damage, were constructed, and the self-test result with samples of modeling group showed that the discriminant accuracies were 71.0%, 84.9%, 87.2%, 100% respectively, with total discriminant accuracy of 80.8%. The test result with samples of validation group showed that the discriminant accuracy and accurate rate were 73.00% and 75.99% respectively, which indicated that there was good feasibility to use Fisher discriminant analysis to predict the Dendrolimus punctatus Walker pest levels. 

    • Control Stability of Active Light Source Spectra during Measuring Reflectance of Canopy

      2014, 45(6):284-290. DOI: 10.6041/j.issn.1000-1298.2014.06.043

      Abstract (3546) HTML (0) PDF 1.28 M (2020) Comment (0) Favorites

      Abstract:With the self-developed measurement equipment of canopy reflection spectrum, the spectral stability of two kinds of narrowband-LEDs, which were used as active light sources and had peak wavelengths of 730nm and 810nm respectively, were studied. The experimental results showed that the junction temperature of the LEDs was significantly increased when the LEDs were pulse-lighted in high frequency based on the request of the measurement. The increased junction temperature resulted in linear red-shift of the light source spectra and linear decrease of luminous intensity of the light source, which seriously affected the stability and reliability of the measuring results. A new method of driving LEDs, named intermittent pulse-driving LED, was proposed. When LEDs were driven in this method, the rise of the junction temperature could be effectively controlled below 2℃, and the red-shift of peak wavelength of light source spectra was less than 1nm. Finally using the self-developed measurement equipment of canopy reflection spectrum, in which this method was embedded, the experiments were implemented both in laboratory and wheat field to measure the reflectance response of the crop canopy. The fluctuation ratio of measured results was less than 5%. The LED-driving method proposed could be applied in developing measuring equipments for detecting reflection spectrum of crop canopy. 

    • Reconstruction and Application of 3D Pig Body Model Based on Point Cloud Data

      2014, 45(6):291-295. DOI: 10.6041/j.issn.1000-1298.2014.06.044

      Abstract (4016) HTML (0) PDF 1.27 M (3151) Comment (0) Favorites

      Abstract:The traditional manual measurement to get the animal growth parameters is high workload, low precision, stress and other issues. For these problems, 120-day-old Landrace samples were chosen for the study, and then got the point cloud data of the pig through the three-dimensional laser scanner, based on the triangulation principle to calculate three-dimensional coordinates of the target point. By Polygon Editing Tool Vel. 2.40 software, the point cloud data were preprocessed, and then the three-dimensional surface model of pig body was reconstructed based on triangulated irregular network. Then the parameters were extracted for pig body length, body width, hip width, height, hip height, chest measurement, body surface area, volume and so on. The results indicated that the 272021 pig point data were acquired by three-dimensional laser scanner, and pig three-dimensional surface was reconstructed by 544042 polygons. By error test method, the detection values by the three-dimensional model and measured values of the body parameter were compared. The regression analysis showed that there was high detection precision in body length, width, hip width, height, hip height, chest and other body parameters. The maximum relative error was only 0.42%, and the average relative error was 0.17%. Using the point cloud data of pig and three-dimensional surface of pig to estimation the shape parameters has high precision and can reduce the workload and give no stress in pigs. It can provide high-precision body size data for estimation model of pig body weight, and technical reference for the other parameters of animal body. 

    • Regulation of LED Night Lighting on Growth and Morphology of Cucumber Seedlings and Process of Night Lighting

      2014, 45(6):296-302. DOI: 10.6041/j.issn.1000-1298.2014.06.045

      Abstract (3483) HTML (0) PDF 1.01 M (1611) Comment (0) Favorites

      Abstract:The effects of night lighting on growth and morphology of cucumber seedlings in different stages were investigated with different light quality to improve seedling cultivation through photomorphologenesis, and the method of night lighting for cucumber seedlings were discussed. Cucumber seedlings were irradiated with 35μmol/(m2·s) red (R) or red and blue (RB) light from light emitting diodes (LED) for 2 hours in the night(19:00-21:00) at the temperature of 18~20℃. The effects of night lighting on growth, hypocotyls length, cotyledon area, stem diameter, leaf area, internodes length, dry weight, chlorophyll content and seedling index of cucumber seedlings at different stage were measured. Logistic curve was used to fitting the growth rate of leaf area. The cotyledon area and stem diameter were improved by 61.60% and 19.55% respectively compared to contrast at cotyledon stage, and leaf area and stem diameter were improved by 61.60% and 19.55% respectively compared to contrast at one leaf stage with R light night lighting. After three leaves stage, leaf area, stem diameter, dry weight, chlorophyll content and seedling index of cucumber seedlings with RB night lighting were improved by 41.92%, 17.75%, 45.45%, 21.92%, 200% compared to contrast, respectively. Night lighting could improve the growth and health index of cucumber seedlings. R light and RB light could improve the growth and health index of the earlier period (cotyledon stage and one leaf stage) and later period (after two leaves stage) cucumber seedlings, respectively. The method of using R light for early period and RB light for later period as night light could improve the quality of cucumber seedlings.

    • >机械设计制造及其自动化
    • Kinematics Optimum Design of a 5-DOF Spatial Parallel Mechanism

      2014, 45(6):303-307. DOI: 10.6041/j.issn.1000-1298.2014.06.046

      Abstract (3134) HTML (0) PDF 3.07 M (1801) Comment (0) Favorites

      Abstract:The square mean dexterity coefficient, which is used to comprehensively evaluate the dexterity of various configurations, is introduced. The influence law of the structural parameters, including the distribution position angle of the joints on the stationary platform and moving platform, the distribution position radius of the joints on the stationary platform, and the distribution position radius of the joints on the moving platform, on the square mean dexterity coefficient are discussed. On these grounds, the structural parameters are optimized. The optimal results obtained are as following, the distribution position angle of the joints on the stationary platform is π/2, the distribution position angle of the joints on the moving platform is 2π/5, the distance between the first joint on the stationary platform and the center of the stationary platform is 650 mm, the distribution position radius of the joints on the stationary platform is 800 mm, and the distribution position radius of the joints on the moving platform is 160 mm. The simulation results show that the square mean dexterity coefficient of 4-UPS-RPS parallel mechanism are creased, so that the obvious improvement of the kinematics characteristics for the parallel mechanism is realized.

    • Stationary Flow Characteristics of Notches on Throttling Grooves

      2014, 45(6):308-316. DOI: 10.6041/j.issn.1000-1298.2014.06.047

      Abstract (3214) HTML (0) PDF 1.52 M (2391) Comment (0) Favorites

      Abstract:Aimed at three different notches with typical structural features, the stationary flow characteristics were investigated thoroughly and critically. The computational fluid dynamics approach was used to investigate the pressure distributions in notches, and the changing rules of the restriction locations were obtained. After deducing the calculation formulas of flow area, the metering characteristics of notches were studied. Based on the relation of flow rate vs pressure drop characteristic, the discharge coefficient as a function of Reynolds’ number was obtained by using experimental study and theoretical analysis methods. The stable value of the discharge coefficient was also given, and its variation pattern with variable openings was discussed. Based on high consistency between theoretical values and experimental results, the steady flow force and throttling stiffness were investigated, and the results agreed with observed ones were obtained. It was shown that spheroid-notch was applicable under the case of rapid pressure establishing as its discharge coefficient was high when the opening was small, and its flow ability was excellent. Triangle-notch was suitable for the circumstances of high precise control due to high throttling stiffness and smooth increase of flow rate. Divergent U-notch was applied to the conditions of rapid response and stability. The research can be extended to structure optimization and characteristics study of notches, and also provide some

    • Online Identification and Correction of Orifice Inlet Edge Bluntness Based on Downstream Flow Field Distortion

      2014, 45(6):317-323. DOI: 10.6041/j.issn.1000-1298.2014.06.048

      Abstract (2955) HTML (0) PDF 1.09 M (1587) Comment (0) Favorites

      Abstract:Online identification of orifice bluntness was put forward, and specific solutions was given. Orifice discharge coefficient of CFD simulation on normal condition and bluntness conditions were compared with GB/T 21446—2008 to verify the validity of the simulation. To achieve the identification, in the rear of the flange pressure points (P1, P2) another pressure point P3 was installed and the differential pressure ratio factor (η) was calculated. The factor reflected the degree of distortion of orifice plate flow field relative to the normal condition, which was the ratio factor indirectly reflected the degree of bluntness. The best position of pressure points P3 was determined by the analysis of simulation results, and the experience formula about the ratio factor with bluntness was further concluded. Through the formula, online identification of bluntness could be realized. The effectiveness of the identification algorithm was verified through real flow experiments. The error of calculated value was within ±1.0% for sharpness correction coefficient (bk), which proved that the algorithm was practicable in engineering. 

    • Fluid Control Mechanism of Mosaic Bionic Coupling Functional Surface

      2014, 45(6):324-328. DOI: 10.6041/j.issn.1000-1298.2014.06.049

      Abstract (3283) HTML (0) PDF 1.69 M (1909) Comment (0) Favorites

      Abstract:Dolphin’s special mosaic skin structure has characteristic of drag reduction. Imitating this special structures, a kind of bionic coupling functional surface was designed. Two-way fluid-solid coupling simulation was carried out on the mosaic bionic coupling functional surface using ANSYS-Workbench software, while the fluid calculation used the standard turbulence model, and the solid calculation used transient structural. The simulation result showed that the turbulent kinetic energy and the surface speed of the coupling functional surface were significantly reduced, and the flexible material produced displacement deformation. The above simulation result indicated, that the flexible material of surface coupled with non-smooth structures of substrate through conforming fluid medium to achieve the control purpose. The elastic deformation of surface material absorbed part of energy, and effectively reduced the turbulent kinetic energy of the fluid medium, to avoid the energy loss caused by excessive exchange between the fluid-solid interface.

    • Fractal Unloading Model of Joint Interfaces

      2014, 45(6):329-332,323. DOI: 10.6041/j.issn.1000-1298.2014.06.050

      Abstract (2917) HTML (0) PDF 1004.73 K (1550) Comment (0) Favorites

      Abstract:A fractal unloading model of joint interfaces was established based on fractal contact theory and unloading model of asperity. The unloading of asperities both elastic and elastic-plastic deformation was taken into account in the model. By numerical simulation, the nonlinear relationship among the real contact areas, contact force, contact pressure and interference was obtained, as was as the difference between loading and unloading. The result showed that the unloading process of joint interfaces was elastic, and depended on the final condition of loading. During the unloading process, the real contact area and contact force depended on the interference of joint interface. When the loading process started, both the real contact area and contact force sharply decreased and smaller than the values during loading. As the interference increased, the real contact area became larger than the value during loading soon, while the contact force was smaller than the value during loading in a wide range of interference. The unloading contact pressure was much less than the loading contact pressure within the entire interference interval. 

    • Prediction of High-speed Machining Kinematic Performance

      2014, 45(6):333-340. DOI: 10.6041/j.issn.1000-1298.2014.06.051

      Abstract (3185) HTML (0) PDF 1.15 M (1971) Comment (0) Favorites

      Abstract:The kinematic performance of the CNC machine tool plays an important role on surface processing quality and contour accuracy of the workpiece in high-speed CNC machining. This paper proposes a kinematic performance prediction method to investigate the dynamic indicators of the CNC machine tool. The feed rate is taken as main researched object. By the control mode of flexible acceleration and deceleration, the equation of state is established considering the constraints of machine tool parameters and the segment connection velocity. The preloading follow-up constraint status is used to simplify the solving for state variable and decision variable of the dynamic programming. The feed rate curves and jerk curves are presented to identify the constraint parameters and constraint axes. The experiment of the specimen cutting is implemented to verify the feasibility of this method. 

    • Surface Roughness of Titanium Alloy under Ultrasonic Vibration Milling

      2014, 45(6):341-346,340. DOI: 10.6041/j.issn.1000-1298.2014.06.052

      Abstract (3554) HTML (0) PDF 1.66 M (1759) Comment (0) Favorites

      Abstract:The effects of processing parameters (amplitude, milling speed, feed per tooth) on surface quality machined by side blades in ultrasonic torsional vibration milling (UTVM) were investigated. Based on a series of UTVM experiments, the influence of single-variable processing parameter on surface quality of milled surfaces was obtained. Furthermore, the significance of these effects of each factor and interactive factors of processing parameters on surface roughness was studied by variance analysis and response surface methodology. Processing parameters were optimized and prediction model of surface roughness was established. The experimental results show that applied ultrasonic torsional vibration can obviously reduce surface roughness of milled surfaces, and the amplitude is the most significant factor of affecting surface roughness in UTVM, while the milling speed and feed per tooth are the second and the third, respecitively. Large amplitude and low milling speed are more likely to improve the roughness of the milled surfaces.

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