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Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the cumbersome feature extraction steps and poor real-time performance of traditional visual servoing algorithms, an end-to-end direct visual servoing algorithm based on convolutional neural network is proposed. By directly predicting the instantaneous linear velocity and instantaneous angular velocity of the camera installed at the end of the robotic arm, servo positioning works without the need to label handcrafted features, camera intrinsics, or depth information. Firstly, the image observed by the camera is input into the GhostNet feature extraction network for information extraction, and the bottleneck attention module (BAM) is integrated into the network to enhance the spatial information and channel information of the target object. Then, the fully connected layer is used as the speed regression function, the linear velocity and angular velocity are decoupled and regressed. Finally, a real-time capture method is used to create the dataset required for training in the real environment, and the velocity labels are generated according to the position-based visual servo control law algorithm. Efficient and accurate localization and tracking tasks are accomplished under the trained initial pose. The experimental test results in a large number of real scenes verify the effectiveness of the algorithm, and it is also robust to scene background information. [ABSTRACT FROM AUTHOR]

In order to solve the problems of difficult control of geometric deformations in roll-forming processes of aerospace thin-walled conical cylinders, three typical abnormal deformation states and formation mechanism of thin-walled conical cylinders were revealed, such as axis deviation, axis tilt and small end retraction. A conical roller motion coordination control method was proposed based on linear velocity feedback of cylinders, and a conical roller motion control model was established. The billet optimization design methods of thin-walled conical cylinders were proposed, and the corresponding core roll inclined feed control strategies were established, which ensured the consistency of the diameter growth rate of conical cylinders and eliminated the small end shrinkage phenomenon caused by the mismatch between the axial and circumferential flows of metal. The finite element models of thin-walled conical cylinder rolling with improved control methods and strategies were established based on ABAQUS software and VUAMP subroutine development. The forming effect of the cone rolling processes under conventional planning control, independent control and comprehensive control was compared and analyzed. The results show that the indexes such as axis offset, roundness error, concentricity error and inclination angle error of cylinder using the comprehensive control method are reduced by 93.6%, 75.3%, 95.1% and 97.2% in the modulation stage, respectively, compared with the conventional planning control. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A four-wheel differential robot was used as experimental platform to obtain environmental information based on single-line liDAR, and the navigation performance of the robot in the center line of the tree and the autonomous line breaking of the robot at the end of the line were investigated. The environmental information was obtained by single laser radar, and the method of distance threshold, the adaptive density clustering algorithm and the improved method of least square algorithm processing laser data were used to obtain the center line of the tree line as robot navigation theory path. The robot and navigation path horizontal offset, heading angle and velocity were selected as input to design the control model of real-time tracking navigation path. The results show that when the robot reaches the end of line, it can automatically sense and execute the turn to the next line. In the inter-row autonomous navigation experiment, when the robot linear velocities are 0. 2, 0. 4 and 0. 6 m/s with the initial lateral offset of robot not more than 0. 8 m and the heading angle not more than 15°, the average lateral deviation between the navigation trajectory and the center line of tree line is 3. 69 cm, and the maximum lateral deviation is 11 cm. In the autonomous line-breaking test, the robot can accurately turn around to the next line and then continue to navigate between the lines. The proposed orchard autonomous navigation system has good operation stability and high navigation accuracy, which can meet the autonomous driving accuracy requirement of orchard robot. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, frequency is regarded as a new characteristic parameter to analyze vibration features. Firstly, the principle of vibration signal feature extraction was proposed, and the characteristic frequency function was obtained through the vibration feature extraction test of quick-point grinding. Then, the influence of different levels of technological parameters on grinding vibration under the machining or idle condition was analyzed. And the variation law of characteristic frequency was analyzed by comparing the contact and energy transfer relationship between the grinding wheel and workpiece. The results showed that the machining characteristic frequency is always smaller than the idle and the relative deviation of characteristic frequency decreases with the increase of the grinding wheel ' s linear velocity, and increases with the increase of grinding depth and feed velocity. At the same time, the influence weight of each technological parameter on the characteristic frequency was compared, and the idea of improving the machining efficiency was put forward. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The experiment aimed at the hammer mill, which is widely used in feed enterprises at present, to carry out the research on corn crushing technology. The BT-2900 dynamic particle image analyzer was used to determine and analyze the particle size of Yunnan maize after being crushed by different treatment groups. The best milling process parameters of maize were determined by range and variance analysis. The results showed that the optimum technological conditions for obtaining the maximum weight geometric mean diameter were linear velocity 55 m/s, hammer screen clearance 12 mm, number of hammers 8, and hammer thickness 2 mm. The grinding particle size would be more uniform and concentrated in the target range. The optimal process conditions were linear speed 85 m/s, hammer screen clearance 9 mm, number of hammers 16, and hammer thickness 3 mm. The study indicates that the linear velocity at the end of the hammer was the primary factor affecting the grain size and uniformity of corn crushing. With the increase of the linear velocity at the end of the hammer, the geometric mean diameter and geometric standard deviation of the weight of the comminution particle size are significantly decreased, and the proportion of the target interval is significantly increased. [ABSTRACT FROM AUTHOR]

The mm-level dynamic maintenance technology is essential to the realization of mm-level terrestrial reference frames. The current dynamic maintenance technology mainly includes the linear maintenance based on linear velocity, the nonlinear maintenance technology that comprehensively considers the nonlinear motion of stations and geocentric motion, and the epoch reference frame. Firstly, the development status of the linear maintenance technology is summarized. The nonlinear maintenance technology and its research progress are discussed by reviewing the modelling method of coordinate nonlinear variation from the influence mechanism and data. Then, the realization process of the epoch reference frame and its application in the maintenance of the reference frames are introduced. Finally, based on the analysis of status quo, several key issues that need to be solved are proposed to achieve the dynamic maintenance of the mm-level terrestrial reference frame. [ABSTRACT FROM AUTHOR]

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Jilin University (Science Edition) / Jilin Daxue Xuebao (Lixue Ban) is the property of Zhongguo Xue shu qi Kan (Guang Pan Ban) Dian zi Za zhi She and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cold-proof mode has widely been updated for some vineyards in Xinjiang Region of northern China. The cold-proof cloth is normally used to assist in soil buried operation for better insulation of heat and moisture in complete soil clearing. However, the machine is still lacking for the soil clearing of winter grape and cold-proof cloth recycling, particularly in the early stage of popularization and application for the cold-proof cloth assisted soil-buried mode. It is also difficult to realize the smooth winding of cold-proof cloth. In this study, a new speed control system was proposed for smooth winding of grape cold-proof cloth in spring in Xinjiang Region, China. The linear velocity of the cloth roll was set to be equal to the forward speed of the machine. This system automatically detected the winding state of the cold-proof cloth. In smooth winding of the cold-proof cloth, the theoretical rotation rate of the DC motor was calculated in real time, according to the real-time changes of forward speed in a machine and the radius of cloth roller. A PID controller was adopted to control the duty ratio of Pulse Width Modulation (PWM) signal, then to adjust the rotation rate of the DC motor, further to drive the cloth roller for winding the cold-proof cloth. As such, the forward speed of the machine was used to realize the real-time adjustment of rotation rate for the cloth roller. At the time of cold-proof cloth deflected winding, the rotation rate of the cloth roller was adjusted to advance or lag the target rotation rate so that the cold-proof cloth was to restore the smooth winding state. Specifically, this study included the structure design of grape cold-proof cloth winding device, the hardware and software design of the control system. A control model was established in Simulink module using the motor transfer function model. In the simulation, the PID parameters were set, where the gain coefficients of proportion, integral, and differential were 0.3, 0.2, and 0.000 05, respectively. A physical prototype was also processed for the speed system. The static calibration test was carried out for the rotation rate of the DC motor, in order to obtain the relation between the motor rotation rate and duty ratio of the PWM signal. A performance test was conducted to verify the feasibility of automatic deflection adjustment for the cold-proof cloth. The optimized mounting distance of 20 mm was achieved for the laser switching sensor. PID parameters in the simulation test were taken as the intermediate levels in the performance experiment for the rotation rate of the DC motor, where each coefficient was tested at 4 levels in turn. The optimized proportion, integral, and differential gain coefficient were 0.3, 0.1, and 0.000 05, respectively, indicating basic consistency with the simulated values. The steady-state response time of the control system was about 0.4 s with a response delay of about 0.1 s, indicating a relatively small influence and good control effect. The performance test of slant winding cold-proof cloth was carried out, where the flatness was taken as the evaluation index. It was found that the flatness of the cold-proof cloth was more than 90% and the average was 92.78%, suitable for the operational requirements. The speed system with better control performance can provide a technical reference for the design and optimization of recycling machinery for the grape cold-proof cloth. [ABSTRACT FROM AUTHOR]

A combined windrower has widely been used for oilseed rape harvest in recent years. However, there is a limit laying space in the small windrower with a narrow swath. The side transmission is also difficult as a result of the tangled and lodged rape, particularly in the branch involvement overhead during cutting and conveying. In this study, a feasible mechanism of inclined transportation was proposed for the large-branch involvement in the oilseed rape, thereby a novel device of inclined transportation was designed for a rape windrower. An inclined windrower table was used for the large laying space of the rape stalk, thereby improving the transport capacity along the transverse direction. A systematic analysis was made on the process of cutting, transporting, and laying stalk in the inclined transportation of a rape windrower, according to the geometrical and kinematic conditions of the stem in the smooth migration. As such, the structural and performance parameters were determined, including the reel speed, conveyor belt speed, and conveyor angle. A field test was conducted to evaluate the laying quality of inclined transportation in a rape windrower. An optimization was made on the structural parameters of working parts to establish the constraint equations of operating parameters for the inclined transportation windrower. A quadratic regression orthogonal experiment was carried out to explore the interaction factors on the laying quality. The evaluation indices included the laying angle, the laying angle difference between the upper and lower floor, as well as the variation coefficient of laying width and height. The ranges of experimental factors were obtained, where the rotate speed of the reel was 26-38 r/min, the linear velocity of the conveyor was 1.4-1.8 m/s, and the conveyor angle was 10-30°. Quadratic multivariate fitting regression and variance analysis were applied to clarify the influence of interaction factors on the performance of inclined transportation windrower. Results showed that the conveyor angle had the most significant influence on the laying quality. A multi-objective optimization model was established after the quadratic regression orthogonal experiment, according to the standard requirements of the rape windrower. An optimum combination of parameters was achieved, including the reel speed of 35 r/min, conveyor belt speed of 1.5 m/s, and conveyor angle of 27°. In the field test, the results showed that the average spread angle was 28.3°, and the relative error with the predicted value was 5.6%, under the optimal combination of parameters. The laying angle difference between the upper and lower laying floor was 5.4°, where the relative error with the predicted value was 12.5%. The variation coefficient of laying width was 9.6% with a relative error of 15.6%, while, the variation coefficient of laying height was 8.6% with a relative error of 11.7%. The accuracy of laying quality in the prediction model was verified by the field test. The swathing loss rate and operating efficiency were0.73% and 1.11 hm2 /h, respectively. The water contents of rape stem and grain were 47.9% and 9.7% after 4-day drying, which decreased by 35.1% and 74.4%, respectively, compared with those before, indicating a great benefit for the following picking and threshing. Compatibility tests of inclined transportation windrower were carried out in the winter rape areas, including the upper middle and lower reaches of the Yangtze River, as well as the spring rape area of North China. The results demonstrated that the inclined transportation windrower can realize smooth transportation, neat laying, high quality, and low loss swathing, suitable for the multi-cropping rape in two-stage harvesting. This finding can provide a sound reference to design and optimize the rape windrower. A further dynamic characteristic of rape stalk during transport and laying is necessary for the better performance of inclined transportation in the future [ABSTRACT FROM AUTHOR]

Identification and counting of specifications are essential to the scallop seedlings before sowing in aquaculture production. Mechanized sowing has become necessary to identify the scallop seedlings with high activity, thereby culturing them in a more sustainable and less harmful environment. In this study, anew automatic device was designed for reasonable specification identification and counting with high efficiency in the scallop seedling. An investigation was made to analyze the system of bottom sowing culture for the seedling of scallop (Patinopectenyessoensis) in Dalian, China. A comparison test was also performed on the island of Changshan, where the scallop seedlings were collected. The specification range of scallop seedling was 20-40 mm in the experiment, where the grading specifications of scallop were set: <25 mm, 25-30 mm, and ≥30 mm. There were two phases for each experiment. In the first phase, an orthogonal experiment was used to analyze the critical influencing factors of specification identification and counting accuracy, and to determine the optimum technological parameters for scallop seedling. In the second phase, the field tests in the actual production situation lasted for 15 d (from October 16th to October 30th, 2019), and 24 groups of comparative tests were conducted. Each group of the test was repeated by 3 times. Specification identification and counting tests were completed by manual labor and machine, respectively. The statistical deviation rate of scallop seedling was calculated at the end of each test, including the total number of workers, and the total time. The optimal technological parameters were achieved for the specification identification and counting device, where the speed of vibration motor was 2100 r/min, the adjustable exit size of scallop was 50 mm×20 mm, the width limit of the primary queuing guide was 55 mm, the angles of baffle were 45°and 30°, the linear velocity was 0.5 m/s, the vertical distance between sensor and conveyor was 50 mm, the horizontal distance between guide mechanism and conveyor was 25 mm, and the time interval was 25 ms set by the system for the scallop seedling to vertically pass the sensor. In this case, the best accuracy was gained for the specification identification and counting, where the average deviation rate was 3.72%. The influence order of each factor on the average statistical deviation rate of scallop seedling was as follows: the time interval set by the system for the scallop seedling to vertically pass the sensor, the linear velocity, and the vertical distance between sensor and conveyor. The results of comparison tests in actual production showed that the deviation rates were 3.67%-4.65% for the specification identification and counting between mechanical and manual manner, where the average deviation rate was 4.02%. There was no significant difference in the deviation rates of specification identification and counting statistics between mechanical and manual manner (P>0.05). Compared with the screen grading and counting device of scallop seedling before optimization, the statistical deviation rate was reduced by about 0.445%, showing better accuracy and stability in the optimized device. The optimized device of specification identification and counting for the scallop seedling was 5.44 times higher than manual operation, and 0.92 times higher than the screen device of scallop seedling grading and counting. It demonstrates that this device has high efficiency to meet the development needs of the green industry. These findings can support mechanized sowing techniques for the reproductive status of scallop seedling in the aquaculture industry. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Different varieties of gift boxes are commonly used to pack eggs, in order to satisfy the demands of consumers. It has brought great difficulties for the automatic packing of eggs. At present, manual packing is often used in egg processing industry in China, considering the variable size of color box, the different quantity of each box, and the fragile physical characteristics of eggs. In this study, a flexible cartoning, and handling mechanism was developed for the color boxes to realize the automatic packing of eggs. The movement trajectory in a Cartesian coordinate manipulator was planned, using the trajectory planning algorithm, thereby to industrialize the flexible packing production line for an egg color box. Besides, the basic physical properties and the packing protection performance of the color box were tested, including drop test, pressure test, frequency sweep test and random vibration test, in order to ensure the stability and reliability for the manipulator holding the color box and avoid the damage of the eggs in the box that caused by the resonance of the production line. The protective performance parameters for the color box were detected, including the critical drop height, the non-damaged clamping force, the resonance frequency, and the non-damaged egg transport system excitation. In the drop test of color box, the results showed that the critical drop height of eggs in the box was 290 mm, while, in the pressure test, the eggs in the box cannot damaged when the clamping force of the color box was less than 870 N. In addition, the frequency test of the color box proved that the resonance frequency of the color box package was 10-15 Hz, and the random vibration test determined that the excitation of the system can meet Grms≤0.52 g²/Hz. The splint and the guide frame can be quickly disassembled under the constraints of the physical parameters for the color box. The egg box can be boxed with flexibility, high efficiency, and low damage using the central controller (Siemens PLC S7-200 Smart) and the touch screen (MCGS) according to the size, specification and quantity of the color box. The maximum effective strokes of the X and Z axial were 750 and 380 mm in the Cartesian coordinate manipulator in the production line. The X-axial velocity of robotic arm was adjustable from 0 to 199 mm/s, while the Z-axial velocity was from 0 to 149 mm/s. The maximum stroke of the Y-axial gripper plate movement was 200 mm, and the maximum linear velocity was 50 mm/s. The rated power of the machine was 1.5 kW. So far, the production line has been running for 11 months on the packaging line, where the mechanical equipment, software and hardware of control system were stable and reliable. An on-site test was performed on the production line for 10 days, showing that the packing efficiency with 6 boxes and 4 boxes in a color box were 96.2 and 120.4 boxes/h, respectively. Compared with manual packing, the efficiency can be enhanced by 4-6 times, indicating that 3-6 assistant workers can be saved, while the damage rate of egg was reach zero in the whole test process. The findings can provide a sound reference to the design and application of the automatic production line of color box for egg packing in food industry. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The real-time tracking of human targets by mobile robot was prone to problems such as scale variations, occlusion and deformation of targets. Aiming at above problems, an improved kernel correlation filtering algorithm (OURS algorithm) based on high-confidence update strategy of model and scale was proposed. The method of one-dimensional fast discriminative scale space was used to solve the problem that the kernel correlation filtering algorithm can't deal with the scale variation. A new confidence measurement method was proposed to judge the detection results of OURS algorithm model. When the target was completely occluded, it switched to Kalman filter algorithm to predict the position of the target. The confidence degree of the scale detection was judged to avoid the wrong scale update of tracking box. Through the video sequence simulation experiment and real environment test, the target tracking effect of the OURS algorithm was verified and compared with that of kernel correlation filter(KCF) algorithm and fast discriminative scale space tracking (fDSST) algorithm. The results show that the proposed OURS algorithm has the precision of 0.758, and the success rate of 0.711, and the target tracking effect of OURS algorithm was obviously improved compared with KCF, fDSST algorithms. The tracking box can still accurately frame the target after the scale variation, occlusion, deformation of pedestrian target, and other factors. The pedestrian tracking system of mobile robot based on image servo control strategy can adjust the linear velocity and angular velocity to maintain a stable following according to the position of the pedestrian. [ABSTRACT FROM AUTHOR]

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Tiangong University is the property of Journal of Tianjin Polytechnic University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the problems that the seed and seed tube collision may reduce the qualified seeding rate and increase the coefficient of variation during the seeding process of the air suction precision maize seed metering device at high working speed, a method of seed throwing in a straight line by using linear seeds pushing device and suction hole of seed plate was presented in this paper. The linear seeds throwing process included three stages. Firstly, seeds attached to the seed plate steadily move in a circle with the seed plate during the range of transition area. Secondly, the seeds moved straight down at an absolute velocity with the seeds linear pushing device during the range of linear pushing area. Finally, seeds entered into the range of linear falling area and accelerated straight down, and then entered the seed tube, the seeds in the seed tube evenly and orderly dropped into the seed ditch. The principle of seed falling in a straight line was analyzed, the motion and mechanical relationships between the seeds and the air suction precision maize seed metering device during the seeds linear falling process were explained, the curve equation of suction hole of seed plate was defined, the structural curve equation of the seed pushing device was determined. In order to explore the effects of seed feeding position and working speed on the seed metering performance of seed metering device, the whole factor test was carried out with the seed feeding position and working speed as the influencing factors, and with the qualified rate of seeding spacing, the missing seeding rate and the coefficient of variation of seeding spacing as the test indexes. In addition, the significance of the test results was analyzed, and the regression equations of each factor and test indexes were determined. The maize seeds of Zhengdan 958 were used as objects of indoor bench test. The results showed that the optimal seed feeding position was that the angle of the linear seed pushing area was 15° and the angle of linear seed falling area was 21°. The verification test results showed that the qualified seeding spacing rate was 98.68%, the missing seeding rate was 0.69%, and the coefficient of variation of seeding spacing was 15.03% at the working speed of 12 km/h, which was consistent with the theoretical optimization results. The comparison tests were conducted between the linear seeding and the ordinary choke seeding. The results showed that all the indexes improved at all working speed on the basis of meeting the national standard requirements. With the working speed increased, the improvement effect became better. At the working speed of 14 km/h, compared with the ordinary choke seeding, the qualified rate of seeding spacing was increased by 4.22 percentage points, the missing seeding rate was reduced by 4.20 percentage points, and the coefficient of variation of seeding spacing was reduced by 4.55 percentage points, which indicated that the linear seeding could effectively improve the seeding effects at high working speed The results of adaptability tests showed that the seeding performance of Xianyu 335, Denghai 605 and Jingnongke 728 was lower than that of Zhengdan 958, but the qualified rate of seeding spacing was higher than 96.5%, the missing seeding rate was lower than 1.8%, and the coefficient of variation of seeding spacing was lower than 17.7%, which still met the requirements of the precision sowing. [ABSTRACT FROM AUTHOR]

Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A double-ring truss deployable antenna mechanism, which is used as the support and deployment mechanism for large-diameter space-borne antenna, is proposed to improve the stiffness of the single-ring truss deployable antenna with large diameter. The structural decomposition of double-ring truss deployable antenna mechanism is conducted, the screw constraint topology graph of the closed-loop deployable mechanism unit is drawn, and the degree of freedom (DOF) of the mechanism is analyzed. The analyzed result shows that the double-ring truss deployable mechanism has only one DOF. The screw velocity of each component in the mechanism is analyzed based on screw theory, the angular velocity and centroid linear velocity of each component are obtained through vector operation, and the Jacobian matrixes are also obtained. Furthermore, the screw accelerations of the components in the mechanism are derived based on the screw derivative, and the angular acceleration and centroid linear acceleration of each component in the double-ring truss mechanism are obtained. A dynamic model of the double-ring truss mechanism is established based on Newton-Euler equation and virtual work principle, and the numerical calculation and simulation verification are carried out. The research results show that the theoretical analysis is correct. The proposed double-ring truss deployable antenna mechanism has a simple structure, and can be smoothly deployed with only one input drive, the kinematic and dynamic analysis method based on screw theory used in this paper has a clear physical meaning, the analysis process is relatively stylized and is easy to program. [ABSTRACT FROM AUTHOR]

In the implantation process of garlic mechanized seeding, under the strong coupling among garlic seeds, soil and parts touching it, the verticality of adjusted garlic seeds is very easy to reduce again, thus affecting the final garlic output and garlic quality. How to ensure that garlic seeds are planted in an upward vertical direction has become a key technology to be solved. To solve this problem, this paper took the planetary wheel garlic planter designed in the early stage as the research object, introduced its structure and working principle in combination with the whole garlic planter, realized the adjustment of the opening and speed ratio of the inserting duckbill by processing the cams of different planters, and changed the opening phase angle of the inserting duckbill by adjusting the circumferential position of the cams installed in the machine. Based on the establishment of garlic inserting seed model and the analysis of the process, the tip motion equation of the duckbill was established and imported into CAXA software to generate the movement track. Through the analysis of the movement track under different parameters, it is clear that the key factors that affect the verticality of garlic seeds after planting are the linear speed of the inserting duckbill, the opening phase angle and the ratio of the opening angle of spigot duck's beak to the center angle corresponding to the cam convex section (the opening and speed ratio). In order to verify the correctness of the theoretical analysis, a garlic planting test-bed was developed, and the indoor experiment of Cangshan garlic planting was carried out. Through the single factor experiment, it was determined that the value range of the linear speed of the duckbill was 200-500 mm/s, the range of the opening phase angle was 0-20°, and the range of the opening and speed ratio was 1-2. In order to obtain the optimal parameters of these three factors, the Box-Benhnken central composite test method was used to design the linear velocity, opening phase angle and opening velocity ratio of the spilt duck's beak by three factors and three levels quadratic regression test. The sowing test was carried out, and the response surface mathematical model was established by using Design-expert software. The key parameters affecting the verticality were comprehensively optimized. The optimal working parameters are as follows, the linear speed is 200 mm/s, the opening phase angle is 20°, the opening and speed ratio is 2. In order to verify the performance of the inserter using the optimized parameters, field experiments were carried out. The results showed that the average vertical degree of garlic seeds in the optimal parameter operation was 63.2°, which was 21.8% higher than that before. It not only met the requirements of garlic planting vertical degree, but also further improved the integration of agricultural machinery and agronomy, which improved the guarantee for large-scale mechanized vertical sowing of garlic. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the rice area of the Northeast China, the large amount of rice straw with low moisture content is tough to chop. However, the existing method of chopping combined auxiliary slitting could not meet the requirements of chopping under such condition, which could cause some problems such as incomplete straw crushing and unqualified rate of straw crushing. It would affect the subsequent land preparation and transplanting operations and caused problems such as machine blocking, straw floating before transplanting and seedling floating during transplanting. In order to solve these problems, this paper designed a straw chopper based on the principle of differential sawing, which could realize the same direction with different speed between the saw disc blade and the crushing knife to achieve supporting sawing. The friction force and relative linear velocity of crushing straw were increased to improve the crushing effect. Structural parameters of saw disc blade, crushing knife and other key components were designed through theoretical analysis, and the structure and operating parameters of the machine were preliminarily obtained. In order to improve the wind velocity and straw feeding performance of the crushing chamber, three kinds of fan blade forms, namely facade fan blade, reverse fan blade and diverse fan blade, were designed to compare with no fan blade through simulation analysis. Simulation results by Fluent showed that the facade fan blade could improve the wind velocity in the crushing chamber and contributed to improving straw fluidity, and the verification test was in accordance with the simulation results. According to the movement track of crushing knife and saw disc blade, the rotation speeds of them were designed. The rotation speed of crushing knife ranged from 1815 to 2475 r/min, accordingly, and the saw disc blade rotation speed ranged from 605 to 825 r/min, to be specific, the ratio of rotation speed between saw disc blade and crushing knife was 1/3 constantly. The dynamics analysis of straw crushing process showed that rotation speed of crushing knife and the tilt angle between the saw disc blade could affect crushing performance. Therefore, a field experiment of two factors with three levels was designed by using the average length of straw crushing and the crushing qualification rate as an evaluation index. The test results showed that the crushing knife rotation speed and angle of slope had a significant impact on average length of straw crushing and straw crushing qualification rate. Considering straw crushing performance and energy consumption, the optimal combination was determined as follows: The crushing knife rotation speed was 1800 r/min and the angle of slope was 65°, the corresponding saw disc blade rotation speed was 600 r/min. The field test results under the optimized combination conditions were as follows: the average length of straw crushing was 9.58 cm, the proportion of straw under 10 cm was 93.23%, and the scatter unevenness was 20.89%, which met the quality requirements of straw crushing and scattering in the northeast rice region. In the paper, a comparison test between the differential sawing rice straw chopper and the ordinary straw chopper was carried out. The filed test showed that the average length of straw crushing of the ordinary straw chopper was 13.42 cm, and the proportion of straw under 10 cm was 71.5%, which was not as good as the differential sawing rice straw chopper, and there was no obvious difference in the scatter unevenness between them. After the chopping operation, the same plow was used for the plowing operation, and the straw burying rate was 98.92% of the differential sawing rice straw chopper while the ordinary straw chopper was 90.21 %. Its successful implementation could greatly improve the operation effect for chopping rice straw and stubble on one hand, and on the other hand provided better growing surface conditions for rice. The design of the machine provided a basis for the popularization and application of straw mulching technology in northeast China. [ABSTRACT FROM AUTHOR]

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

At present, the packing or sieve tray is widely used in the LPG extraction tower of the alcohol amine purification unit. This paper focuses on the design of packing tower and sieve tower. For the packing tower, the packing height, tower diameter, distributor, redistributor calculation or estimation methods were given, and the minimum amine to LPG flow ratio required by random packing and structured packing was provided. For the sieve tray tower, the methods of calculating or estimating the sieve hole diameter and the velocity through the holes, the operating linear velocity of dispersed phase, the tray spacing and the tower diameter were given. The typical dispersed phase feed setting mode and the structure of the sieve tray column dealing with low volume flow ratio of two phases were also provided. A comprehensive feed treatment measure for LPG extraction tower was put forward, which is the LPG coalescer was used to remove the water-soluble harmful substances from LPG, and a filtration system, including primary filter, activated carbon filter and secondary filter, was installed to remove impurities from the lean amine pipeline. It was pointed out that activated carbon filter could effectively adsorb soluble organic pollutants dissolving in amine solution. The suggests were as follows:(1) the amount of lean amine treated by activated carbon filter was 15%-25% of the total amount of lean amine circulation rate; (2) the residence time of amine solution in the bed of activated carbon should not be less than 15 minutes; (3) the activated carbon filters were designed according to one for operation and one for preparation. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Large displacement and large amount of fluid volume fracturing is increasingly becoming an effective way of shale gas reservoir development. The friction reducer performance is the critical performance of volume fracturing which directly determines the success or failure of the volume fracturing. This paper studied the relationship among “shear velocity, linear velocity, the Reynolds number, relative molecular mass, concentration and water quality” with the friction reducer performance. The results showed that using shear rate similar principle could not effectively evaluate friction reducer performance of slickwater. The performance of friction reducing was recommended to be evaluated by the linear velocity and Reynolds similar principle. When the friction reducers had similar structure and consistent effective concentration, the bigger relative molecular mass, the friction reducing performance was better. But high relative molecular mass would cause the cut-resistant and dissolving performance poorly. The concentration of friction reducer increased, the friction reducing performance improved, but when the concentration increased to a certain value, the friction reducing performance increased smaller; when friction reducer concentration was lower than a certain value, the cut-resistant performance was poor. Water quality had an impact on friction reducer performance,namely higher the salinity, better the cationic friction reducer performance . [ABSTRACT FROM AUTHOR]

The nonlinear dynamics of tethered satellite system is studied for the attitude motion of mother satellite. Firstly, the planar dynamical model of two degree-of-freedom is established for a tethered satellite system moving in an elliptical orbit during station-keeping phase. The periodic motion is obtained by performing the perturbation analysis with the orbital eccentricity as a small parameter. Afterwards, the stability of the periodic motion is analyzed using Floquet theory. The effect of the parameters of the system on the bifurcations of periodic motion is revealed numerically. It is found that the coupled attitude and pitch dynamics causes the co-existence of quasi-periodic motions, and yields the chaotic motion as increasing the size of the mother satellite. Finally, a linear velocity feedback control scheme is successfully applied to stabilize chaotic motion. [ABSTRACT FROM AUTHOR]