Abstract:Automatic detection of apple defects using a computer vision system is difficult due to the similarity between stem-end/calyx and true defects. Identification of stem-end/calyx is always a challenging project in automatic apple grading. This paper presents an encoding method based on position change for spot-array structured light, and the proposed method was used in distinguishing defects from stem-end/calyx of apple images in real time. By analyzing imaging process of the spots projected onto the object surface and reference plane, the position change of spot was chosen as coded primitive. Over the field of two elements, the M-array was generated by using the primitives, and was used as the coded pattern of near-infrared(NIR) spot-array structured light. Analysis of difference matrix made it possible to identify the location of stem-end/calyx regions after matching. The on-line experimental results demonstrated that the proposed method could realize the detection of stem-end/calyx efficiently, and achieve an average of 93.17％ recognition accuracy with real-time performance. The results indicated that the proposed method was effective in identification of apple stem-end/calyx.

Abstract:Scene recognition is the key to visual navigation for the agricultural mobile robot in unknown environment. This paper used what-where dual channel theory to build the models of scene perception, scene representation and scene recognition, and proposed a bionic method of scene recognition on the basis of probabilistic framework. This method first computed the bottomup saliency map of scene based on the contrast prior and the center prior, which can be further optimized with the global energy function. Then shifted the visual focus of saliency map to obtain the saccade sequence as the “where information”, and analyzed the content of the visual focus to obtain the “what information” with the experts network comprised of single layer perceptron. Lastly, according to the action recognition regularity of human, built the discrete and observable Markov model using the “what information” and the “where information”. The parameters of the model can be determined by training the frame images from the camera on the mobile robot and can be viewed as the prior knowledge about different scenes, which can be recognized by maximizing the likelihood probability of the Markov recognition model. The whole recognition process is similar to human`s. Experimental results show that this method has good performance for indoor scenes and the recognition accuracy averaged out at 87.3%.

Abstract:In order to achieve real-time variable dressing in wheat jointing stage, spectral data processing strategy and expected fertilizer quantity calculation model were studied. The variable rate fertilization expert decision system was developed based on crop canopy real-time spectral information (Normalized differential vegetation index, NDVI). Combined with NDVI information, actual traveling speed of dressing machine and feedback amount of fertilizer, the dual-channel independently controlled the speed and the opening of institutions to real-time adjust the amount of fertilization. The comparative experiments of ratio fertilization and traditional fertilization for winter wheat with different base fertilizer rates in Jiangsu Huanghai Farm were carried out. In order to improve the efficiency of expert decision system, the optimal data processing strategy was analyzed. Results showed that the best data processing frequency of the expert decision system was 1Hz. Using more fertilizers was beneficial to promote the winter wheat individual growth, but it was not conducive to the structure of the group. The variation coefficient of NDVI in control area was the largest, as high as 11.32%. Variable fertilizer could effectively reduce the variation cofficient of NDVI, decreased by up to 3.57% and the average of 1.46%. The fertilization precision can reach above 90%. Variable rate fertilizer applied more nitrogen (28kg/hm2) than quantitative fertilization. Variable rate fertilization would help to improve wheat population structure and reduce the yield differences. Therefore, the expert decision system was favorable, and could achieve precise fertilization in the precision agriculture.

Abstract:A pincette-type end-effector using two fingers and four pins for picking up seedlings was designed. When the end-effector extracts seedlings from the tray cells, its two cylinder fingers push out the four pick-up pins to penetrate into the root soil deeply, and then the pick-up pins are closed to hold the soil of the seedlings firmly for lifting. When the end-effector releases seedlings at the discharge point, its two cylinder fingers open and the pick-up pins loosen the soil of the seedlings and pull the pick-up pins back for discharging. Based on the physical and mechanical properties of plug seedlings as related to the automatic transplanting work, the mechanical design of end-effector was conducted according to the requirements of extracting seedlings. A prototype of the pincette-type end-effector was constructed and test-operated to examine whether or not its functional requirements were satisfied. As the extraction speed was 40mm/s, there were no significant effects on the extraction force for picking up seedlings from the tray cells under various parameters. In the orthogonal experiments, it was found that the root soil moisture content exerted the greatest effect on the root damages in the pick-up process, and other factors such as penetration angle, penetration depth, and root system had no significant effects. As the penetration angle was 11°, the penetration depth was 32mm, the number of seedlings in the cell was 4, and the root soil moisture content was 55%~60%, the minimum root soil damages in picking up seedlings from the tray cells using the designed pincette-type end-effector can be achieved.

Abstract:Considering that the existing seedling seeder for rice paddy field adopts manual push and pull, and has large differences in sowing performance, a precision seeder which was suitable for seeding in southern rice paddy fields was designed so as to reduce the intensity of labor and to improve the sowing qualified rate, uniformity and stability. A control system of the walking seeder was developed, which used STC12C5608AD singlechip microcomputer as the core control unit, PWM (Pulse width modulation) as control output of motor speed. The whole system has realized speed feedback with pure P proportional closed control algorithm, so that sowing performance of the seeder was stable and sowing qualified rate was about 5% higher than manual push and pull. Based on further analysis of sowing mechanism of spiral grooved wheel device, as well as control system of the walking seeder, the orthogonal tests were conducted to further investigate the effects of these parameters on sowing performance: depth groove (h),lead angle (α) of spiral grooved wheel and seeder speed (v). The results showed that the best operational parameter combination was that h of 3mm, α of 81.73°, v of 0.35m/s. Sowing performance tests based on the best parameter combination were done. After the control system was installed, the sowing qualified rate of hybrid rice (2～6 grains per grid) was improved from 87.14% to 93.21%, and the inbred rice (3～8 grains per grid) was 92.14%. Meanwhile, the empty rate of inbred rice was 0%, and the breakage rate was less than 0.20%. The control system has achieved automatic control of sowing process for seedling precision seeder, and the sowing performance can greatly meet the agronomic requirements of precision seedling in rice paddy field for hybrid rice and inbred rice. This study lays research foundation of precision seeding technology for rice paddy field seedling.

Abstract:Existing rotary planting mechanism perform is not well in planting large spacing vegetable pot-seedling (plants spacing above 450mm) in the practical transplanting work. A new planting mechanism with planetary gear train, which is suitable for planting pot-seedling with large plants spacing, was designed. By constructing a transmission ratio function of the non-circular gears and calculating the center coordinates of each parts, the kinematic model of the planting mechanism was established, including the equations of (angular) displacement, (angular) velocity for the end point of planting mouth. According to the established mathematical model, computeraided analysis and optimization software of the mechanism based on Visual Basic 6.0 was developed. Then through analyzing the planting trajectory, which was influenced by several key parameters including center distance of the non-circular gears, angular displacement coefficients, initial installation angle of the planetary carrier, the planting mouth and the middle non-circular gear, etc., and also using the human-computer conversation optimization method，a set of mechanism parameters were found to meet the requirements of vegetable pot-seedling planting．Based on the optimized parameters, 3D model was established and simulation analysis was proceeded. Then, physical prototype of the planting mechanism was made and field planting experiments were conducted. Land planting tests were carried out and the different opening and closing time of the planting mouth impacting on the upright degree and success rate of the planted vegetables potseedling were researched. It is proved that the best opening time is when the planting mouth arrives at 10mm distance above its lowest position, in this case, the rate of seedling perpendicularity reaches 85%, planting efficiency is 100 plants/(min· row) and plants spacing is 450mm. Thus the mechanism was verified suitable for large spacing planting of vegetable pot-seedling.

Abstract:The planting arm of rotary transplanting mechanism for rice pot-seedling is the operation component which is used for seedling picking-up. The motion of seedling control and pushing will affect the success rate of seedling picking-up and seedling pushing directly. Aiming to solve the problems such as the long time of seedling picking-up, low success rate, no pushing device and poor pushing seedlings of the original pot-seedling transplanting mechanism, the transplanting mechanism was redesigned. The main work is to redesign cam mechanism in transplanting arms using optimization design method, decrease cam-drive angle and add the seedling pushing device. With the development of virtual prototype and physical prototype, the virtual kinematics simulation and the kinematics test with high-speed digital video camera and image processing technology were carried out. The basic consistency of the shortening time in two test was demonstrated which showed the feasibility and availability of the developed design of planting arms. The seedling picking-up tests of transplanting mechanism with different cam mechanisms as well as the transplanting mechanisms with and without seedling pushing device were developed. The success rate of seedling picking-up and seedling pushing of the developed mechanism were 94.3% and 98.6%, which were 82.9% and 88.6% higher than those of the product by original pot-seedling transplanting mechanism, respectively. It was proved that the improved mechanism can meet the requirements of rice pot-seedling transplanting.

Abstract:Variable fertilization technology is an important part of precision agriculture. According to the requirements of agricultural production, the SYJ-2 type three-point suspension liquid variable fertilizer machine was designed which was matched with wheeled tractor. Taking the single chip microcomputer as the core processor and the electromagnetic proportional adjusting valve as the execution unit, the control system for liquid variable fertilizer and the upper computer software works in concert with hardware were designed and programmed for collecting data and sending the command. The key components, which called rotary pricking hole mechanism, used five congruent oval gears to drive. The liquid fertilizer flew in the cavity of rotary pricking hole mechanism. This agency reduced the external connecting hoses at the same time and prevented the pipe twine. The function of the liquid fertilizer distributor was opened and closed timely. The mechanism could achieve discontinuous injection of liquid fertilizer, then complete the injection operation of liquid fertilizer. The structures for distributor and intracavity rotary pricking hole mechanism were designed at the same time. The field experiment results showed that the fertilization depth was 12~15cm below the soil surface, and the fertilization accuracy was 99.1%, which meets requirements of liquid fertilizer for variable fertilization.

Abstract:Knotweeds are important medicinal materials in China, which have good effect in restoring circulation, dispersing stasis and relieving cough. During the knotweeds root processing, they are hit many times omnidirectionally to separate it from the soil. In order to separate knotweeds from the soil in a mechanical way, a roots-soil separating device of knotweeds was designed, which consists of hitting roller, turning-throwing roller, grille, etc. In the experiment, it was found that finger length had influence on soil-divorcing. The range of spiral angle of turning-throwing roller finger pole which is 180～275mm, was set through velocity vector projection theorem. On the other hand, the relationship between the horizontal distance about axle centers of two rollers and the size of knotweeds was developed by fitting tool of Matlab software. The result showed that rate of soildivorcing and efficiency were 91.2% and 1.35t/h, on condition that speed of hitting roller, turningthrowing roller and horizontal distance of two roller were 500r/min, 240r/min and 230mm, respectively, and therefore the device met the manufacturing requirements. It provided reference for research of soil-divorcing of crops.

Abstract:In order to overcome the shortcomings of traditional linear soil-bin test bed, a kind of rotary round soil-bin test bed was proposed. To compensate the processing and assembly errors of the large-size round soil-bin test bed and provide convenience for the following simulating field trials of agricultural machinery, a driving scheme of rotary round soilbin test bed driven by tire friction was optimized. Mechanical adjusting device for initial installation position of the rotary round soilbin test bed driven by tire friction was designed, and the soil-bin roundness compensation capability was calculated. The control system for the proposed rotary round soil-bin test bed was designed, and the closed-loop system was established with PLC as controlling unit and servomotor as executive device. All of these made the soil-bin test bed run at a steady speed; it was found that the test bed can compensate for roundness of soil-bin, it can smoothly run at the speed of 0~3.8r/min, the maximum standard deviation of speed fluctuation was 0.038r/min, the longest time required from the start to smooth running was 9.8s. Transplant experiment with planting mechanism was carried out; the spacing coefficient of variation was 4.46% which means good uniformity and can well meet the transplanting agronomic requirements.

Abstract:Truss type sprinkler cart is one of the main parts of traveller irrigation machine, which plays an important role in modern agricultural irrigation. However, the sprinkler cart may get overturned or broken in the fields because of its large spraying arm span, unreasonable span setting between wheels and/or excessive moisture of the fields. Thus, a parameterized dynamics simulation model was established for type JP75 sprinkler cart in the software ADAMS to improve its abilities of slopeclimbing and antioverturning. Qualitative performances of the sprinkler cart were analyzed based on the proposed model. The slope angle was taken as an evaluation index of slopeclimbing and antioverturning abilities. Several key factors affecting the climbing abilities greatly were optimized, such as attachment coefficient, wheel spacing and centroid height. The bisection method was firstly brought into the simulation of sprinkler cart to accelerate the algorithm convergence. Compared with the current machine, simulation results show that the optimized sprinkler cart improves its stability by increasing the slope angle with 21.48%. Moreover, a physical prototype was developed and a field test was conducted to confirm both the accuracy of the simulation and the validity of the methods adopted. Test results show that both the number of overturn and torsion extent of the cart were decreased greatly with the water distribution uniformity increased dramatically. The abilities of slopeclimbing and antioverturning of truss type sprinkler cart were improved significantly. This paper provides a new method for the design of truss type sprinkler cart.

Abstract:Air-assisted spraying technique research was carried out to increase pesticide efficiency and decrease pesticide loss. The spraying performance was experimentally studied on model 3WQ-3000 trailed air-assisted boom sprayer in small bell stage of corn fields. The effects of four sizes of flat fan nozzles（ST110-02, ST110-04, ST110-05, ST110-06） with air curtain on pesticide efficacy, coverage rate and loss rate were carried out. The experiment results showed that the deposition amount was large at upper part of corn canopy and small at lower part. Air curtain enhanced penetrability, deposited property of droplets and improved the uniformity of distribution at corn canopies. Air-assisted sprayer had significant influence on small size droplets VMD that the pesticide efficacy of ST110-02 flat fan nozzle with air curtain was 83% more than that without air curtain. The optimum pesticide efficacy of ST110-06 flat fan nozzle with air curtain was 41.93%. Air curtain could increase pesticide loss rate on the ground. The best loss rate of ST110-02 flat fan nozzle without air curtain was 13.05%. Compared with the conventional sprayer, the new airassisted sprayer had better droplet coverage rate and higher penetrability, the average pesticide efficacy was improved by 144.17%, and pesticide loss rate on the ground was reduced by 14.46%.

Abstract:Data logging rain gauges and two-dimensional video disdrometer (2DVD) were applied to measure its water application rate, droplet diameter and velocity in radial direction of Nelson D3000 blue spray plate sprinkler with 4.76mm nozzle. The equations of peak application, peak kinetic energy rate about working pressure and mounting height were regressed based on the diffusion of water application and kinetic energy under different working conditions. The result indicates that the diffusion of water application rate and droplet kinetic energy are facilitated by increasing the working pressure and mounting height. This is due to that the jet flow speed is higher when the operating pressure increased, and with the air turbulence enhanced, it is easy to smash. The water drops to pieces. At the same time, the duration of landing increased when the mounting height is high. That seems to have the same effect. The low nozzle height which presents high peak application and kinetic energy rate leads to the generation of runoff. The peak water application and droplet kinetic energy rate varied from 166.4mm/h to 196.4mm/h, and 0.607W/m2 to 0.821W/m2 , respectively. The equation of peak rate can be helpful to design the working pressure and mounting height in sprinkler systems to prevent high peak application rate and kinetic energy rate which leading to occurrence of runoff.

Abstract:Based on the research of working condition and speed variation of elevator on the grain combine harvester, the kinematics and physical mechanics of grain movement on the momentum sensor were analyzed, and then a model of the mass flow sensor named voltage/elevator rotating speed model was put forward to improve the estimation accuracy of grain yield, so that the relationship between grain mass flow and impact force was described deeply by the proposed model. In the harvesting experiments, there existed many vibration noises. In order to eliminate those noises and ensure the accuracy of yield prediction, the impact voltage signals needed to be further processed. Firstly, a regression difference method was used to reduce vibration interference. Secondly, a dual threshold denoising method and two kinds of interpolation methods were proposed to eliminate the singular value of the difference voltages. One of the interpolation methods was threshold replacement and the other was formervalue replacement. The formervalue replacement method could relatively keep the real yield data, and its estimation error was smaller. Furthermore, the rotating speed was normalized to eliminate the influence of dimension and simplify calculation. Consequently, a standardized processing method of impulse voltage was put forward. The verification results showed that the proposed voltage/elevator rotating speed had a high accuracy and the RMSE was 2.03%, which could really characterize the actual situation of grain movement.

Abstract:In order to issue the problem of heavy damage of kernels during threshing corn ear, the bionic thresher was designed according to the excellent ability of beak inserting chink among kernels with low damage and the low cracked rate of differential thresh with bare hand. The thresher mainly includes discrete rod, threshing rod and differential rod. The correlative experiment of the bionic thresher and TY-4.5 thresher was done. As for the Zhengdan958 corn ear, the unthreshed grains rate of the bionic thresher was 0.30%, the cracked grains rate was 0.31%, and the corn cob was unbroken; the unthreshed grains rate of the TY-4.5 thresher was 0.29%, the cracked grains rate was 0.90%, and the corn cob was broken heavily. As for the Xianyu335 corn ear, the unthreshed grains rate of the bionic thresher was 005%, the cracked grains rate was 0.35%, and the corn cob was unbroken; the unthreshed grains rate of the TY-4.5 thresher was 0.09%, the cracked grains rate was 0.95%, and the corn cob was broken heavily. The results showed that the cracked grains rate of the bionic thresher was less than that of the TY-4.5 thresher under the similar unthreshed grains rate, and the corn cob was unbroken. The bionic thresher was suitable for threshing the seed corn ear.

Abstract:To improve the operating quality of the micro rice-wheat combine harvester in hilly and mountainous areas, an air-flowing cleaning unit was designed. By means of design and calculation, the main working parts’(cleaning unit, suction tube and suction fan) structure parameters and working parameters were defined. Simulating analyses on 3D model of air-flowing field in the cleaning unit were done. The results showed that the cleaning device structure and distribution of air-flow speed met the design requirements well and the cleaning effect was good. The compared field test with the rice harvest showed that the micro combine harvester with air-flowing cleaning unit had the features of compact size and easy operation. The distribution of air-flowing velocity and pressure in the cleaning unit could meet design requirements well. Comparing to micro combine harvester without air-flowing cleaning unit, the total loss rate decreased from 3.8% to 2.34%, the damage rate decreased from 1.5% to 1.4% and the impurities rate decreased from 7.2% to 1.2%, which fell by 38.42%, 8.33% and 8333%, respectively. Every performance reached the demands to JB/T 5117—2006 well. The decline of impurities rate was particularly significant.

Abstract:On the basis of the development status of total mixed ration mixer in China, the paddle-wheel total mixed ration mixer was developed. To reveal mixing principle of the mixer, the mixing chamber was divided into four districts, and research of the mixing process was conducted by using high-speed cameras (1200 frames/s, 4G). This study showed that shear mixing, convective mixing and diffusion mixing were the main modes in the mixing process, and accompanied by gliding motion, waterfall movement and eddy motion. It could be obtained that the rotor speed, angle of the mixing paddle, mixing time and fullness coefficient had greater influences on the mixing performance of the paddle-wheel total mixed ration mixer. Then, the above four parameters were decided as experimental factors, and variation coefficient was chosen as the evaluation index, experiments were done by design method of quadratic regression orthogonal rotational combination. Through the experimental study on paddle-wheel total mixed ration mixer, the main parameters in structure and motion of the mixer were optimized and determined as follows: rotor speed of 29~31r/min, the angle of mixing paddle of 16°~26°, mixing time of 10~12min, fullness coefficient of 48%~53%. The research of paddle-wheel total mixed ration mixer could provide a theoretical support for the optimum design and performance forecast of the mixer.

Abstract:Operational efficiency and working quality of silage round baler were mainly determined by the compression chamber. For the feeding difficulties of traditional compression chamber, a new type of round bale device with logarithmic spiral geometric features was designed for the silage job. This device consists of a preload feeding mechanism and the logarithmic spiral type secondary extrusion mechanism. The pressure angles of this machine were experimented with different moisture contents of corn stalks. Results of field test indicate that, plugging problems were solved by using logarithmic spiral geometry chamber baler compared with the circular cavity compression chamber balers. The pressure angle of logarithmic spiral baler feeder must be less than 20° under the feeding process of thick, hard and moist materials. Under the conditions that the pressure angle of 15° and the moisture content of 50%～70%, the feeding speed could match the baling speed in higher efficiency. To form bales of equivalent mass, the device had good adaptability for high moisture corn stalks. The design principles and experimental results of logarithmic spriral compression chamber provided an optimization direction for improving the working efficiency of silage round baler.

Abstract:In China, especially in the northwest region, alfalfa is often planted in mountains and hills, which makes mechanized harvesting become a big problem. The small selfpropelled mower, which is flexible and easy to move, is regarded as a proper solution to the problem. Taking the adverse working condition and the harvest requirements of alfalfa into consideration, the profiling device is the key part of this kind of mower. The research theoretically analyzed the profiling device which consists of sliding palm, spring, linkages and elevating hydraulic cylinder. Building the virtual prototype and carrying out the orthogonal experiment by using the model, the best parameters of the device were as follows: the sliding palm length of 188mm, the cutter bar tilt angle of 4.06°, the ratio of spring pull force to cutting table gravity of 0.85, and the advance speed of 2m/s. By using the optimized mower conditioner test in the field, the result of test showed the validity of the simulation. Besides, under the same working condition, the height of stubble was 7% as low as which was cut by prototype without optimization, and what’s more, the optimized mower worked 75% as fast as the prior machine.

Abstract:In order to analyze the horizontal distribution characteristics of different influence radius preferential flow paths and the spatial associations of biological activity in purple sandstone regions of farmland (vertical soil depths of 10~50cm) in Three Gorges Reservoir Area, the spatial point pattern analysis method (g(r) function) of quantitative ecology was used. After the Monte-Carlo stochastic simulation test, the results showed that the number of preferential flow paths with the same influence radius decreased with the soil depth’s decreasing, while the number of preferential flow paths with different influence radii decreased in the same soil layer. The preferential flow paths with lower influence radii only displayed an aggregated distribution at a small scale (0~20mm). But the aggregated distribution was obviously as the increase of influence radius and scales. The preferential flow paths with different influence radii also displayed an aggregated distribution in deeper soil layer. The preferential flow paths with higher influence radius were more significantly aggregated distribution than those with lower influence radius. The distribution and formation of preferential flow paths were not only influenced by the soil swelling and shrinkage, but also exhibited a positive correlation with animal activity in spatial associations, especially the preferential flow paths with larger influence radius (R≥1.0mm). The spatial point pattern analysis method is simpler than CT and soil water breakthrough curves methods to estimate the preferential flow paths. This proposed method can quantitatively analyze horizontal distribution characteristics of the preferential flow paths with morphology and it is better to reveal the underlying formation process.

Abstract:Visible-near infrared (VNIR) diffuse reflectance spectroscopy has low accuracy in estimating soil phosphorus (P) and potassium (K). We used database of 1582 soil samples from 8 soils to investigate P and K content. All samples were oven dried, ground, and sieved with a 2mm screen. Each sample was divided into two subsamples. One subsample was tested by chemical method. Another subsample was scanned by an ASD FieldSpec Pro FR spectrometer. Data were collected using FieldSpec RS3 software. All spectra were recorded between 350nm and 2500nm and output at a1nm interval. Each soil sample was scanned 3 times with the sample cup rotated within the sample holder to angles of 0°, 45° and 90°. The three spectra of each sample were averaged. Spectral data at the lower visible wavelengths were removed due to their low signaltonoise ratio; and the last 50nm at the high near infrared wavelengths were also deleted for the same reason. Then spectra from 401nm to 2450nm with 1nm interval were reduced by averaging five successive wavelengths. 〖JP2〗Thus, the number of spectral variables was 410. Pretreatments of log10(1/reflectance) plus mean normalization plus median filter smoothing with or without direct orthogonal signal correction (DOSC) were investigated. Results from partial least squares regression (PLSR) with leaveoneout crossvalidation were: the root mean square error of prediction (RMSEP), the determination coefficient of prediction (R2) and the ratio of standard deviation to RMSEP (RPD) were respectively 27.343mg/kg, 0.309, 1202 for P， and 70975mg/kg, 0.421, 1313 for K when DOSC was not used. The value of RMSEP, R2 and RPD were respectively 21.464mg/kg, 0.574, 1531 for P，and 53.485mg/kg, 0.671, 1743 for K when DOSC was used. Additionally, calibrations using only those samples within the approximate range of interest for fertilizer application to field crops (P from 0 to 27mg/kg and K from 0 to 192mg/kg) were investigated. Value of RMSEP of calibration models by PLSR with DOSC decreased by 26.93%(P(0,27)) and 27.67%(K(0,192)), but R2 and RPD increased respectively by 108.31%, 36.90%(P(0,27)) and 87.01%, 38.29%(K(0,192))comparing with models by PLSR without DOSC. The results of this research showed DOSC algorithm can eliminate spectral signal noise might be caused by soil type, texture, etc. for estimating soil P and K using VNIR. DOSC might be a good pretreatment method of spectra for testing soils P and K by VNIR.

Abstract:To explore the spatial variability of soil salinity at root zone in cotton field under plastic drip irrigation, we conducted field experiments in 2013 and 2014 and employed the coefficient of variation, mean relative deviation and standard deviation to investigate the spatial variability of soil salinity for 0~5cm, 5~10cm, 10~15cm, 15~20cm, 20~30cm and 30~40cm layers, and further confirmed representative points that well reflected average soil salinity for each layer. Results showed that for 0~40cm depth, variation degree of soil salinity of only a few points were strong, and most points were medium. Furthermore, in this main root zone, temporal stability of soil salinity first obviously increased and then slightly decreased with increasing of depth. Its stability was the strongest in 30cm depth under surface, with the smallest floating range of mean relative deviation and the smallest mean standard deviation. Based on these findings, some representative points could be selected to estimate average soil salinity for 0~5cm, 5~10cm, 10~15cm, 15~20cm, 20~30cm and 30~40cm layers, and the spatial distribution of the selected points was concentrated. Besides, the relationship between the salinity of representative points and that of the whole area showed a good linear correlation, with high accuracy and determination coefficient from 0.7912 to 0.9171. This research on temporal stability of soil salinity in main root zone can help to guide the field irrigation. And selecting as few representative points as possible can provide a theoretical basis for observation points of soil salinity in this region.

Abstract:This paper discovers the soil temperature and meteorological factors’ impact on soil thermal status in seasonal frozen under the condition of snow cover. We measured the soil temperature in the depth of 5, 10, 20, 40, 60, 100, 140cm under the condition of bare land, nature snow cover, snow compressed and snow thickened. Based on field experimental data, grey correlation analysis was used to select the main meteorological factors affecting the soil thermal conditions and then we calculated the correlation between soil temperature and meteorological factors. Results shows that the existence of snow hampers the energy exchange between soil and environment, causes the difference between the soil temperature and freezedthawing process, and with the increase of depth of the snow cover, soil freezing and thawing date will be delayed, the soil temperature will be relatively stable at a high level. Meanwhile, the difference of temperature between soil and atmosphere will enlarge. In the process of freezing and thawing, environment temperature is the main controlling factor of soil temperature; snow cover makes the correlation between meteorological factors and soil temperature weaker.

Abstract:Studies on rill morphological characteristics can reveal soil erosion mechanisms, and rill morphology has important influence on runoff and soil loss of the hill slope. However, the existing studies only use rill density, rill width-depth ratio, etc. to characterize rill morphology, which cannot fully reflect rill morphological characteristics. Effects of rainfall intensity and slope gradient on rill erosion and rill morphology at the loess hill slope were studied based on a rainfall simulation study. The experimental treatments included three rainfall intensities (50, 75 and 100mm/h) of representative erosive rainfall on the Loess Plateau and three common slope gradients (10°, 15° and 20°) of rill erosion occurrence. The results showed that both soil erosion and rill erosion increased with increasing of rainfall intensity and slope gradient, where relationships among them were the power function. Rill inclination angle concentrated between 16°~20° under the experimental conditions, and it increased with an increase in rainfall intensity and decreased with an increase in slope gradient. Rill density, degree of rill dissection and rill tortuosity complexity were 0.74~1.95m/m2, 0.08~0.17 and 1.09~1.38, respectively, which all increased as rainfall intensity and slope gradient increased. Rill width-depth ratio was 1.93~2.35, which decreased with increasing rainfall intensity and slope gradient. By analyzing correlations between rill erosion and rill morphological indicators, degree of rill dissection is the best indicator to evaluate rill erosion and rill morphology. When studying the effect of rainfall intensity on rill morphology, indicators of degree of rill dissection, rill tortuosity complexity and rill inclination angle are recommended to preferentially select. When analyzing the effect of slope gradient on rill morphology, indicators of rill density and rill width-depth ratio are recommended to preferentially select, except for degree of rill dissection. Most of rill cross sections presented “V” shapes. Generally, the rill cross section appeared more and more irregular change with increasing rainfall intensity and slope gradient, where the runoff turbulence increased. This indicated that the change of rill cross section can reflect change characteristics of runoff, thereby reveal the rill erosion mechanisms.

Abstract:In order to study the transpiration characteristics of matured jujube tree and their transpiration difference of different tree-ages, the transpiration of jujube tree were monitored continuously for three years with TDP sap flow monitoring system. The results indicated that the change of daily jujube transpiration showed a single peak trend, and the trend of narrow peak-wide peak-narrow peak appeared with the change of growth periods. Timelag phenomenon and threshold existed distinctly in jujube transpiration influenced by VPD and PAR. The upper thresholds of VPD and PAR responding to the transpiration were 3.5kPa and 1000~1200μmol/(m2·s). Daily jujube transpiration showed a single peak trend obviously during the whole growth period, the proportion of nighttime transpiration was about 5%~33% of the fullday transpiration. The order of jujube transpiration from large to small was 3a, 5a and 12a during 2012—2014. The significant differences were found between transpiration (p>0.01), and the interannual variations (Cv) of transpiration were different. The transpirations of 12a jujube were not significantly different among years (p>0.05), annual water consumption was basically stable at 293~334mm. Thus, the jujube transpiration scale gradually expanded with the increase of ages, but it could remain stable relatively by taking reasonable pruning measures.

Abstract:Current situation of biogas engineering technology was overviewed and its development prospect were analyzed. Generally, with the growing popularity in China, biogas engineering technology has made great progress. The technology for collection, storage and pretreatment of raw materials need urgent upgrading. More and more researches are required to develop key technology and equipment. It is significant for the efficient and stable operation of biogas project to realize effective monitoring and timely warning and develop appropriate trace element additives and functional microbial agents. Testing and development of new membrane materials and blending or modification of conventional materials were the primary means to improve the separation and purification capabilities of biomethane from biogas. The resourceful utilization of biogas slurry is the key steps for the sustainable development of biogas engineering. Further development of biogas technology claims to realize the standardized integration of independent research and development, standardized engineering design, industrialized production of equipment, modular construction and installation, and professional installation and debugging along with full argumentation of technical bottleneck, rational allocation of resources of science and technology, and increased investment in scientific problem tackling based on the demand of biogas engineering industry 〖JP3〗development, besides, innovating the application mode of biogas engineering technology is also important and helpful. This paper can provide certain reference for biogas industry practioners and related researchers.

Abstract:To realize photo-biological hydrogen production under continuous flow mode, a groove-type flat-panel photobioreactor (GFBR) with high specific surface area was developed by carving groove on the surface of high-light transparent medium. With photosynthetic bacteria attached on the groove-type surface and the generated mature biofilm, cell-immobilization was finished within GFBR. To improve the performance of hydrogen production in GFBR, operating parameters related to substrate were comprehensively investigated using response surface methodology of Box-Behnken with three factors and three levels. The results showed that the significant degree of single factor on hydrogen production rate of GFBR was followed as hydraulic retention time, initial pH value and initial substrate concentration. While, interaction effect between initial pH value and initial substrate concentration on hydrogen production rate of GFBR was also significant. The optimum hydrogen production rate of 2 242mmol/(L·h) was attained with operating parameters of initial substrate concentration of 54.3mmol/L, hydraulic retention time of 21.5h and initial pH value of 7.1.

Abstract:Moisture content is considered as an important evaluation index for beef quality. This study focused on development of nondestructive rapid detection system device for assessing beef quality based on VIS/NIR spectroscopy. Working principal and process of the system, hardware composition, and software were introduced. Hardware of detecting system included two spectrometers, handheld probe, control instrument, bifurcated optical fiber, power unit and container. Two spectrometers in the spectral region of 400~960nm and 900~2600nm were coupled together for spectral acquisition. The wavelength range of visible and near infrared spectroscopy was covered and the characteristic wavelengths in VIS/NIR band of moisture, protein, fat and other main components of beef were detected by the two spectrometers. Another important part was probe. The handheld probe was designed with two optical channels in order to reduce the effect of light source on fiber probe. One channel was designed with angle of 45° for light source and the other one was designed to be vertical for the fiber probe. Inner surface of the two channels was covered by white barium sulfate to make the light distribution even. The handheld probe was designed to ensure the same distance between the end of fiber probe and the surface of sample. Experiment showed that different samples could be detected by adjusting distance between the end of fiber probe and the bottom surface of handheld probe. One end of the bifurcated fiber was connected with handheld probe and the other two were connected with two spectrometers. Software of spectral data collecting and rapid detection was developed by using VC++, and can be run in Windows environment. Main modules of the software included parameter setting module, sample information management module, trigger control module, spectral information acquisition module, quality evaluation module and results display and storage module. The system could collect spectral data, process the data, detect the quality of sample and display the results. First, the system was used to acquire optical data from 57 beef samples of M. longissimus dorsi, and build the prediction model of beef moisture content by visible spectra, NIR spectra, full spectra, respectively. The results showed that the prediction model developed by full spectra had the highest accuracy. The correlation coefficient of calibration (Rc) and the correlation coefficient of prediction (Rp) of the prediction model were 0.96 and 0.88, respectively. Then, experiment on the system was done to detect moisture content of beef on the processing line in two beef slaughtering enterprises. In this test, 84 beef ridge samples were extracted for moisture content detection. The detection results from the experiment yielded satisfactory results. Correct rate of non-destructive rapid detection system device testing on moisture content was 92.8%. The result shows that the system can be used for nondestructive rapid detection of beef quality with high accuracy and reliability as well as repeatability.

Abstract:The oil stained vinegar capsule and the qualified vinegar capsule are of the same color, which makes it difficult to detect oil stained vinegar capsule using the naked eye or computer vision. The spectral information of hyperspectral data is sensitive to the chemical compounds of sample area, and allows quantitative/qualitative analysis of biological products. Therefore the feasibility of using hyper-spectral imaging technology for rapid determination of oil stained vinegar capsule was investigated. The hyperspectral image data of oil stained vinegar capsule were acquired in the wavelength range of 430~960nm, and were used to extract characteristic information of oil stained vinegar capsule. Linear discriminant analysis (LDA) and K-nearest neighbor algorithm (KNN) were used to build discriminant models for oil stained vinegar capsule. When principal component factors equaled to 2 and K levels equaled to 3, the optimal KNN model was obtained with identification rates of 100% in both training set and prediction set. The overall results show that hyper-spectral imaging technology could extract the spectral characteristics of oil stained vinegar capsule efficiently. The hyper-spectral imaging technology could be used for rapid determination of oil stained vinegar capsule.

Abstract:This paper proposed a method to identify the mechanical damage of fruit based on the combined hyper-spectrometer and electronic nose. We used hyper-spectrometer and electronic nose on no damage guava, lightlevel mechanical damage guava and heavylevel mechanical damage guava samples, respectively. After extracting the feature information, the principal component analysis (PCA), linear discriminant analysis (LDA), Euclidean distance (ED) analysis and fuzzy Cmean cluster were used to compare the classification effect of three identification methods (hyperspectral identification, electronic nose identification, combined hyperspectrometer and electronic nose identification) for guava mechanical damage. The results of PCA and LDA show that the hyper-spectrometer and electronic nose can identify the mechanical damage of guava, but both of the single method cannot identify the mechanical damage level of guava. When using the method of combined hyper-spectrometer and electronic nose identification, LDA result shows that it can classify the mechanical damage level of guava effectively. The identification effect of LDA for guava mechanical damage was better than that of PCA. According to PCA, LDA and ED results, we can also infer that the multisource information fusion can not only gain more sample information which was useful for improving classification effect, but also keep the maximum distance of each group as large as possible. According to fuzzy C-mean cluster results, the identification accuracy of guava mechanical damage based on hyperspectral identification, electronic nose identification and combined hyper-spectrometer and electronic nose identification were 89.74%, 82.05% and 97.44%, respectively. This paper proved the feasibility of using multi-source information fusion to improve the identification effect of fruit mechanical damage.

Abstract:Hyperspectral imaging technology covered the range of 450~1000nm was employed to detect natural defects (shrink, crack, insect damage, black rot and peck injury) of Huping jujube fruit. 663 sample images were acquired which included five types of natural defects and sound samples. After acquiring hyperspectral images of Huping jujube fruits, the spectral data were extracted from region of interest (ROI). Using Kennard-Stone algorithm, all kinds of samples were randomly divided into training set (500 samples) and test set (163 samples) according to the proportion of 3∶1. Partial least squares regression (PLSR) and successive projections algorithm (SPA) were conducted to select optimal sensitive wavelengths (SWs), as a result, 9SWs and 10SWs were selected, respectively. And then, least squaressupport vector machine (LSSVM) discriminate model was established by using the selected wavebands. The results showed that the discriminate accuracy of the SPA-LS-SVM method was 93.2%. Then, images corresponding to ten sensitive bands (535, 595, 657, 672, 685, 749, 826, 898, 964, 999nm) selected by SPA were executed to PCA. Finally, the images of PCA were employed to identify the location and area of natural defects feature through imaging processing. Using Sobel operator, region growing algorithm and the images of PCA, the edge and defect feature of 163 Huping jujube fruits could be recognized, the detect precision was 90.8%. This investigation demonstrated that hyperspectral imaging technology could detect the natural defects of shrink, crack, insect damage, black rot and peck injury in Huping jujube fruit in spectral analysis and feature detection, which provided a theoretical reference for the natural defects nondestructive detection of jujube fruit.

Abstract:Hyperspectral imaging which integrating both spectroscopic and imaging techniques with higher spatial and spectral resolution, has been developed to study the physical characteristics, chemical constituents and distributions of different quality attributes. It’s difficult to further analyze because of the adverse effects produced by the curvature of spherical objects in the process of hyperspectral images acquirement. Its suitability was illustrated in a specific case of apple fruits. This study proposes a method for correcting the light intensity of radiation nonuniform on the apple fruits. Firstly, the original hyperspectral images were corrected into the reflectance hyperspectral images based on black and white reference images, resulting in reducing the influence of illumination and the dark current of the camera. Then, the mean spectra extracted from roundness region of interest (ROI) in centre area of hyperspectral image were used to develop calibration models by using partial least squares (PLS) regression. The correlation coefficient and root mean square errors of calibration were found to be 0.9305 and 0.4331, respectively. After applying the proposed correction, the spectra of the pixels in hyperspectral image were performed to calculate the sugar content of corresponding pixels. Finally, the visualization of sugar content distribution in apple was achieved by using pseudo-color mapping. The results demonstrated that the correction method was proved to be effective for eliminating the adverse effects produced by the curvature of the fruit on the intensity of the radiation. The hyperspectral imaging has a great potential to be a nondestructive and rapid tool for the quantitative measurement of sugar content distribution for apple.

Abstract:Light permeability of tree affects the accumulation of sugar in fruits, and there is a difference in quality of fruit between different types of trees. The effect of tree shapes on prediction of sugar content of Huanghua pears in harvest time by visible/near infrared spectroscopy (VIS/NIR) was evaluated. A total of 480 pears were picked from opening canopy trees and trellistrained trees in six batches, there was significant difference in fruit sugar content between two types of fruit trees (p<0.05). The root mean square error of prediction (RMSEP) and residual prediction deviation (the ratio of standard deviation to RMSEP, RPD) of models of single tree shape fruits for predicting similar fruits ranged from 0.69°Brix to 0.64°Brix, and from 2.08 to 1.97, while for all fruits of different tree shapes, they ranged from 1.31°Brix to 1.07°Brix, and from 1.14 to 1.36, respectively. The RMSEP of the combined model was 0.59°Brix, and RPD was 2.38. The results showed that the model established by single tree shape fruits had poor performance, while a model established by using combined shapes fruits would obtain ideal robustness and good accuracy. The results would help to further utilize VIS/NIR to test quality of fruits in harvest time and predict the optimal harvest time.

Abstract:In order to solve the problems of conventional air-impingement dryer such as small loading capacity, no uniformity of drying and crustation, a tilted tray air-impingement dryer was designed. This apparatus was composed of tilted tray skip, drying chamber, hot air recycling system, humidifying system and control system. The technological and structural parameters of the dryer, for instance, drying temperature, absolute humidity, airflow velocity, inclination angle, separation distance and nozzle arrangement can be adjusted according to different material properties and products requirement. The experimental results of Hami melon slices demonstrated that the drying uniformity coefficient can reach to 0.97. The carrying capacity and the dehydration intensity of the dryer were increased by 1.7 times and 3.65 times, respectively, compared with the conventional air-impingement dryer at the same temperature. And the drying time was shortened by 11.1% at the same time. The unit energy consumption of Hami melon slices treated by tilted tray air-impingement dryer was about 67.9% lower than that by the conventional way. Both the browning degree and shrinkage level were better than that of the latter. This research improves the loading capacity and adaptability of materials, which provide significance in enlarging applied range of air-impingement technology.

Abstract:The thermal dynamical and rheological properties as well as mathematical simulation analysis of rice seeds were studied by dynamic mechanical analysis (DMA). A long grain hybrid rice variety (Jinyou 974) grown in Hunan Province of China was used in this investigation. The results showed that the thermal transition was observed obviously and the length change of rice seeds with a loaded constant force along the major axis direction was detected during temperature scanning. The glass transition temperature decreased from (71.37±2.76)℃ to (31.84±2.51)℃ with moisture content increased from (11.3±0.23)% to (24.3±0.47)%. Both the linear function and Gordon-Taylor model can adequately represent the variation of glass transition temperature with moisture content (R2> 0.98). In order to do more in-depth study of thermal dynamical properties of rice seeds, the creep and stress relaxation characteristics were tested on the basis of temperature scanning. 5-element Kelvin model and 3-element Maxwell model could match the creep and relaxation behavior of rice seeds well and the results showed that the creep behavior was significantly affected by its moisture content and length, while the relaxation behavior was only influenced by its moisture content. These indicated that there would be unavoidable stress cracks because of the influence of creep and relaxation during storage and transportation process.

Abstract:Informationization has become one of the essential emerging technologies,which supports the innovation and sustainable development of modern fishery. In order to promote the application level in aquaculture, the knowledge mining technology, parameter identification and organization forms of perception network, research status of acqusition and monitoring for information of regional water environment, and change of breeding area and its spatial and temporal characteristics were summarised according to the attributes and scale of the information,the flow of farming activities and the hierarchy of modeling and applications. And models of prediciton and early warning of water quality, methodologies of knowledge representation and inference in aquatic desease diagnosis, quantitative and analytic methods of aquatic products’ behaviors, establishments of nutrition formula and feeding decisionmaking system, perception contents and constructions of platform in traceability, and control strategies and methods in aquaculture system were analyzed and compared by systematically summarising and clarifing the literature. The results indicated that the aquaculture industry has been penetrated profoundly by information technologies for comprehensive perception and decision support; the information acquisiton has been transformed from artificial to digital intelligence, such as perception networks and remote sensing; information processing was developing towards the process of modeling: the expert systems, management systems, decision support systems, traceability systems and precision control systems, which were based on artificial intelligence, information fusion and intelligent information system; and the applications of information has also paid more attention to mutual adaptation, promotion and optimization between the thoughts of information and management and aquacultures’ operational efficiency and benefits.

Abstract:Vegetation temperature condition index (VTCI) drought monitoring results retrieved from Landsat remotely sensed data (30m) in Guanzhong Plain, China were spatially transformed to a scale of the Aqua MODIS resolution (930m) by using point spread function, mixed pixel area weighting method and median pixel variability weighting method. The transformed VTCIs were compared with the ones retrieved from Aqua MODIS data for agreement analysis of the two drought monitoring results. Taking MODIS VTCIs as the ‘real’ droughts, correlation coefficients and root mean square errors between the upscaled Landsat VTCIs and MODIS VTCIs, and the texture and semivariances of the two VTCIs were applied to select the best transformation method. The results showed that the transformed VTCIs from the point spread function and the mixed pixel area weighting method were better than those from the median pixel variability weighting method, which indicates that the point spread function and the mixed pixel area weighting method were both suitable for transforming the retrieved VTCI drought monitoring results from Landsat remotely sensed data, and the data processing procedure of the point spread function was relatively simple. The transformed VTCIs in the selected sampling sites covered by winter wheat showed that the smaller the spatial heterogeneity, the higher the transformed accuracy.

Abstract:High temperature stress has serious influences on the yield and quality of corn. The yield loss would be devastating if heat injury happened at corn flowering stage. The Huang-Huai-Hai Plain is one of corn predominance regions in China, where high temperature damage often occurs in recent years. This study aims to explore the temporal and spatial distribution of the high temperature stress of corn at flowering stage in Huang-Huai-Hai Plain. Firstly, we determined hours per day of temperature higher than 34℃ at flowering stage as the index for heat injury, then we calculated the index value of each county in the Huang-Huai-Hai Plain during 2013, and analyzed its temporal and spatial distribution of the region. Secondly, based on the meteorological data in 63a, we calculated the 2013 probability of high temperature stress at corn flowering stage in the region. The result shows that, Pingdingshan City, Xinyang City of Henan Province and area near by encountered unusual high temperature at flowering stage in 2013, where the probability of 2013 was below onceinacentury. In order to reduce yield loss and overlapping time between the corn flowering stage and high temperature period, we suggested to sow about one week in advance for these areas. In background of the climate change, research on the temporal and spatial distribution of corn high temperature damage is significant to react the disaster mitigation of maize production.

Abstract:Morphology and microstructure of particulates with the application of different gas compositions in EGR were analyzed by using transmission electron microscope and image processing software (Digital Micrograph). The results show that the particulates with the application of CO2 mainly have the chain structure. The disorder degree of carbon layer in elementary particulate is higher and the content of graphitic crystalline structure in shell is less than those particulates with the application of EGR. Besides, the fringe separation distance has a significant increase. The average fringe length has a significant decrease; the tortuosity is the biggest and the fractal dimension is the smallest. The particulates with the application of N2 mainly have the stone clusters; the elementary particulate integrated more tightly; the core of elementary particulate is more obvious and the content of graphitic crystalline structure in shell is less than those particulates with the application of EGR. Besides that, the fringe separation distance has a significant decrease; the average fringe length has a significant increase; the tortuosity is the smallest and the fractal dimension is the biggest. Those indicate that the structure of particular with the application of N2 is more tightness than those with the application of CO2, and increasing of the content of CO2 in EGR can improve the oxidation ability of particulate and decrease the disorder degree of carbon layer.

Abstract:For rotary engine, the changes in port timing can bring change, not just to admission efficiency, but to the the flow field and turbulence energy in cylinder. On the basis of the Fluent simulation software, a threedimensional dynamic simulation model was established through the secondary development to write dynamic mesh programs and choose the reasonable turbulent model, combustion model and CHEMKIN mechanism. The threedimensional dynamic simulation model based on the chemical reaction kinetics was also validated by using the experimental data. On this basis, the working process of peripherally ported natural gasfueled rotary engines under different port timings was simulated. The results show that with the intake duration angle unchanged, as the intake opening angle was brought forward, the intensity of the swirls and the vortex blobs, the volumetric coefficient all increased, and the turbulence intensity near the ignition position also increased. The increase of the turbulence intensity near the ignition position can significantly increase combustion rate, but the whole combustion rate in combustion stage did not always increase with advanced intake opening angle. With the intake duration angle unchanged, when the intake opening angle was 407°, the flame propagation speed reached the maximum value, the indicator diagram was the best and the emission of NO was the biggest.

Abstract:In order to explore the mechanism of fuel droplet impact on surface in diesel engine small-size combustor, a numerical model was developed using coupled level set and volume of fluid method including heat transfer and contact resistance. This model was verified by using experiments. The effect of wettabilities and the mechanism of droplet fluid and heat transfer as well as splashing during spreading were obtained according to results analysis. The theoretical condition of splashing is developed based on energy conservation equation. The results show that when the droplet contacts with the surface, it presents surface oscillation, spread and splash as the impact velocity increases. Spreading factor is closely related to impact velocity, the higher the impact velocity is, the larger the spreading factor is. The dimensionless time of maximum spreading factor is uncorrelated to impact velocity, the higher impact velocity is, the larger contraction is. The effect of wettabilities on spreading factor decreases with increasing impact velocity. The pressure gradient inside droplet is the main factor resulting in droplet spreading, breakup and splashing. Rayleigh-Plateau instability and capillary wave results in the shrink, breakup and splash from the liquid sheet. The conclusions are significant to spray control technology.

Abstract:An improved A* algorithm based path planning method for unmanned underground loadhauldump (LHD) was proposed and verified. According to the articulated structure of the underground LHD, the nodes were expanded by the articulated angle, which makes the expended nodes match the trajectory characteristic of the LHD. In order to avoid collision, collision threat cost was designed and added into the evaluation function, which makes the navigation path exclude against the walls. Simulation and comparison results between the improved A* algorithm and tranditional one show that the improved A* algorithm is more efficient, and the shortest path without collision can be obtained when the weighting coefficient is 0.2. Moreover, a path planning and tracking test is carried out in lab environment. It is shown that the tracking precision can keep in a small range and the LHD can run without collision when the navigation path is given by the proposed algorithm, which proves the effectiveness and feasibility of the proposed algorithm.

Abstract:Kinematic and dynamic performance of a parallel mechanism is, to some extent, determined by its topological structure, so topological structure analysis and synthesis is very important to research and application of parallel mechanisms, especially the parallel robot mechanisms. In order to achieve computer aided topological structure analysis and synthesis of parallel mechanisms, the topological structure of parallel mechanism must first be represented symbolically. An algebraic symbolic description system was proposed for parallel mechanisms on the basis of SOCbased mechanism composition principle. With this symbolic description system, topological structure of any parallel mechanism can be expressed as a symbolic polynomial, each item of the polynomial represents a branch of the parallel mechanism. The transitivity of kinematic pair orientation relations was discussed and symbolic representations of different kinematic pair relations were introduced. Based on this symbolic description system, position and orientation characteristic (POC) set of parallel mechanisms can be derived easily with the help of a computer program, i.e. POC set of a branch was sum of the POC set of each kinematic pair in this branch and POC set of the complete parallel mechanism was product of the POC set of each branch. The proposed symbolic description system features the algebraic property of a symbolic computer language, so it can be used reliably in computer aided mechanism studies. Work in this paper provided a theoretic basis and an effective method for computer aided analysis and automatic generation of parallel mechanisms.

Abstract:Giant magnetostrictive actuator characterized with strong bias magnetic field was designed to control the injector bullet valve opening and closing. Working principle of the actuator was described and suitable sinusoidal signals were analyzed by its bias characteristics. Semistatic model of the actuator displacement was established through reluctance theory, J-A model, quadratic domaintransfer model and linear system theory. Based on the model, the relationship between displacement and current amplitude under square signal was achieved, so did the displacementcurrent curve under sinusoidal signal and the displacementtime curve under square signal with the amplitude of 3A. Experimental system for the actuator was established, and the signal directions were recognized by testing under square signals with the same value while opposite directions. The testing displacements under sinusoidal and square signals were acquired. From the results, the displacement amplitudes under square signals and displacementcurrent curves under sinusoidal signals, calculated through the model, were similar to the testing results. Then the validation of the semistatic model was verified. The simulation of the actuator with an ordinary electrical injector input was done. With the square signal input in the amplitude of 3A, the steadystate displacement of the actuator was above 30μm, responding time was about 10μs, and overshoot was 0. The simulating results showed good performance of the actuator.

Abstract:The arrangement, number and spacing of hemisphere-segments directly influence the pumping performance of pump. By deducing theoretical pumping flow rate, the essential reason of pumping fluid was revealed. Flow field and simulation flow rate of pump were studied with different numbers and spacings of hemisphere-segments respectively arranged in longitudinal and transverse directions. And the result shows that the changes of arrangement, number and spacing of hemisphere-segments mean that the flow resistance differences between reverse and forward flows were changed. The rules were proved that reducing the transverse spacing, appropriately increasing the longitudinal spacing and increasing hemisphere-segment quantity in proper spacing range could all enhance the pump flow rate. Finally, the simulation conclusion was verified by using pump flow rate test. The experiments were carried out by valveless pumps installed in four hemispheresegments with the same spacings of 10mm arranged in longitudinal and transverse directions, and the experimental flow rates were respectively 48.29mL/min and 50.29mL/min; the deviations between experimental and simulation flow rates were respectively 34.6% and 34.0%. The conclusion is further validated that under the same conditions, the better pumping effect can be obtained by increasing the number of hemispheresegments in transverse arrangement than that in longitudinal arrangement.

Abstract:Dielectric electroactive polymers have wide application prospects in research field of biomimetic robots due to the advantages such as large strain, high efficiency, high energy density, etc. 1-DOF rotary joint was designed based on the actuation principle of bionic joint and the characteristic of cylinder actuator. The electromechanical coupling model of DEAP (Dielectric electroactive polymer) of actuator was constructed based on the large elastic deformation theory, then the nonlinear relationship between input voltage and output angle of joint could be obtained by solving the equations iteratively, but this process of computing was timeconsuming. To avoid the complicated calculation, CMAC (Cerebellar model articulation controller) neural network and PD controller were combined to realize the nonlinear mapping between the output angle of joint and input voltage. Tracking control experiments were performed in tracking step and sinusoidal reference signals, which showed the feasibility of CMAC neural network control method, while reasons for long response time and phase difference were discussed in details.

Abstract:Based on the screw theory, the degree of freedom of the 3-PPR parallel mechanism was computed, also the kinetic characteristic was analyzed according to its structural features, and the integrated inverse kinematics was established based on the analytic method. In order to solve the problem of parallel mechanism forward kinematics, this paper proposed a method that translated this problem into objective function optimization, and also built its mathematical model. By improving the basic ant colony algorithm effectively, an ACA was developed for solving the continuous optimization problem. Then this method was used to solve the forward kinematics problem of the 3-PPR parallel mechanism, and it was put into simulation by Matlab. Compared with traditional numerical method, this improved ACA was better at global optimization, and it could avoid the unfavorable effects caused by initial values, so did the local optimal values, also the calculation process will be much simpler without solving the Jacobian matrix and its inverse matrix. Then it is proved that this method is useful for solving the forward kinematics of common parallel mechanisms.

Abstract:The double 1R pseudorigid body model of the compliant joint was put forward for the first time based on the pseudorigidbody model of the initial bending beam. And a dynamic equation of parallel robot system with compliant joints was proposed based on Lagrange method and the virtual cutting method. The dynamic response was obtained numerically. It is shown that there were lowamplitude highfrequency vibrations on the basis of the desired results in the theoretical results, while there was no apparent highfrequency vibration in the results of the simplified model. It indicated that the theoretical model was better than the simple model to reflect the characteristics of such rigidflexible coupling system. Simultaneously, ADAMS-ANSYS united simulation model and the experimental system were accomplished. And the theoretical trajectory was compared with simulation and the experimental trajectory, respectively. The maximum relative errors were 2.41% and 4.69%, respectively, which proved the correctness and validity of the theoretical model.

Abstract:Model registration is widely used in localization and inspection of parts. It remains a challenging problem in some situations. The density of the measured points of the parts depended on the surface curvature in 3D optical scan measurement technology. The local surface in small curvature was to enable more accurate representation with comparatively sparse measured points. Thus the area authorized by each point was different. So each point should be endowed with different status in registration progress. In addition, for a complex part with multiple free form surfaces, different precision requirements were often specified to different regional surfaces in design, and manufacturing process might make the precision difference in regions. Without consideration of the difference, the existing registration methods were prone to obtain the result which balanced the surface error. In the case, the error of the surface with high precision became larger than the physical truth, and the error of low precision regions turned out to be just the opposite. Based on the two aspects, a registration method based on composite weighting parameters of measured point area and regional geometric accuracy was proposed. Composite weighting parameters were constituted by estimating regional precision iteratively and calculating the area of the Voronoi diagram of each measured points. They controlled the influence of different data on the registration. As a result, the registration conformed more to the real engineering. Both theoretical and experimental results verified the efficiency and availability.

Abstract:To improve the mechanical strength of the honeycomb panel heat exchanger and ameliorate the limit of swellcrush forming, the main factors which affecting the welding limit cohesion and limit strength of stamping rupture were optimized. These factors included the welding shape, welding power, welding speed, welding distance, and welding arrangement. The single factor experiment and multi factors experiment for welding sheet mechanical strength were carried out with digital controlled laser welder, pulling test rig, hydraulic pressure pump and other apparatuses. The results of the single factor experiment showed that the sheet limit mechanical strength of spiral welding spot was the largest. With the increase of welding power and welding speed, the limit mechanical strength of spiral welding spot first increased then decreased. The limit strength of stamping rupture of equilateral triangle arranged welding spot was relatively good. With the increase of welding distance, the strength decreased rapidly. The result of orthogonal experiment showed that: with the spiral welding spot and equilateral triangle arranged welding spot, the maximum limit strength of stamping rupture reached 8.6MPa which was improved by 7.5% compared with current welding technology when the welding distance was 50mm, welding power was 2.2kW, and welding speed was 2.5m/min.

Abstract:To achieve detection of tiny defect in radiographic images with complex background, the segmentation method of tiny defects was studied under the conditions of strong noise and large gray gradient background. The visual attention model for radiographic testing image was proposed, and its realization method was analyzed in detail. The human visual attention mechanism was simulated. The line scanning strategy and selfadapting centralperipheral difference strategy was adopted. Based on the vision saliency, the feature map and the saliency map were achieved, and visual attention region was segmented from radiographic images with complex background. Each visual attention region was marked and ordered with visual saliency competition. According to the saliency threshold, the suspicious region was identified. So the image data to be processed was reduced and the interference was discharged from other parts of radiographic testing image. Then attention focuses of the suspicious region was used as the seed point. Based on region growing and visual saliency, a segmentation method for tiny target was introduced to accurately extract tiny defects in suspicious region image. In the experiment about complex radiographic testing image with more tiny target objects, each area containing unknown defect was accurately extracted. Segmentation for tiny target achieved good results. The accuracy rate was 96.1%，and it was 8% higher than that of the traditional method. The results prove the effectiveness and adaptability of the proposed method.

Abstract:The power consumed by bulldozer’s main working parts—bulldozer blade accounts for about 40% of the total power of the bulldozer in working process. It has great significance to optimize the structure and working methods of bulldozer blade’s macroscopic soilengaging surface, thus decreasing working resistance and increasing energy efficiency. Combined with the classic design theories and research achievements of bulldozer blades, the modular design of directrix form and cutting angle shall be conducted for macroscopic soilengaging surfaces structure of bulldozer blades. Nine bulldozer blade models with the cutting angles of 50°, 55° and 60°, respectively, whose soilengaging surface directrix consists of arc, parabolic and bionic curve respectively, were fabricated and designed with scale model. The resistance features of nine bulldozer blades were studied through indoor soil bin and orthogonal experiment model. The result shows that the interaction between directrix form and cutting angle, and the directrix form has great influence on working resistance with significance level of 0.25. Compared with the traditional circular arc surface bulldozing plate, the paraboloid can relatively reduce the horizontal working resistance by 4.6%, the bionic surface reduced by 16.0%. The vertical resistance is reduced by 4.8% and 51.4%, respectively. The research result has important reference value for the highefficient and energysaving design of bulldozer blades and wide tine soil cutting components related.