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In response to the problems of low efficiency, high labor intensity, and low mechanization in manual tobacco harvesting, a comb-off tobacco picking device for southern hilly tobacco areas was designed following the agronomic requirements and the principle of manual picking of tobacco harvesting in southern China. The device was composed of the power chassis, picking mechanism, and storage mechanism. This study involved the theoretical analysis, structural design, and modeling of the key components, such as chassis structure, combing-type picking mechanism, and power synchronization mechanism. The results of the motion analysis and calculation of the picking process demonstrated that the adjustment range of the comb chain elevation angles was from 12.4° to 20.9°, the comb rod installation distance was 76.2 mm, and the synchronizing mechanism transmission ratio was 3:10. One-factor test and three-factor three-level orthogonal test was performed with the forward speed of the chassis, the distance between the picking device baffles and the elevation angle of the chain with the combing bar as test factors, and the rate of broken and missed tobacco picking as evaluation indicators. It was revealed that the optimal combination of the forward speed of the chassis, the distance between the baffles, and the chain elevation angle were 1.5 km/h, 75 mm, and 12.4°, respectively. Moreover, verification tests suggested that the breakage rate of tobacco leaves was 9.99%, and the probability of missed tobacco picking was 7.31%, both of which satisfy the agriculture requirements and the operational requirements in the agricultural machinery certification syllabus. [ABSTRACT FROM AUTHOR]

The occurrence of slope instability disasters seriously endangers the safety of people's lives and property in China. Therefore, it is essential to study the slope instability process and the interaction between soil and retaining walls. In this paper, the smoothed-particle hydrodynamics (SPH) method, based on the elastoplastic constitutive model of rock and soil, was used to simulate the entire process of slope instability and the interaction between soil and retaining walls. The model, based on the classical elastic–plastic theory, includes linear elastic deformation and plastic deformation following the non-associated flow rule under the Drucker–Prager (DP) yield criterion. By considering the plastic characteristics of geotechnical materials, this method can accurately simulate the slope movement process. The model was established, calculated, and compared with a slope example, thus verifying its feasibility. Furthermore, the motion response of the retaining wall under different conditions was studied, which provides a new numerical simulation platform for the stability checking of the retaining wall and motion analysis after the interaction between the retaining wall and slope soil. [ABSTRACT FROM AUTHOR]

Uniform crushed straw throwing and seed-sowing machines can achieve the processes of straw chopping, straw transport, sowing, fertilization, and straw mulching at the same time, which is widely used in many areas of China. Conveying device is one of the important components used to convey, elevate and throw straw. However, the problems of high power consumption and congestion affect the promotion of the machine. Therefore, the conveying device of uniform crushed straw throwing and seed-sowing machine was analyzed in order to determine its device operation mechanism. Kinematic and dynamic analyses of particles of crushed rice straw during lifting and dispersion are used to develop a flexible-body model of rod-shaped and agglomerate-shaped crushed straw and a coupling model including the mechanical structure of the device. By integrating computational fluid dynamics and the discrete element method, the gas-solid coupling theory in numerical simulations and motion analysis of crushed straw particles is used to determine how the flow field and motion characteristics affect the conveying performance. Besides, regression equations to describe the relationships between the factors and each assessment index were established by using the regression analysis and response surface analysis with the software Design-Expert. The effect of throwing blade speed X1, conveying volume of crushed straw X2, and pipeline diameter X3 on the throwing speed of crushed straw Y1 and specific power consumption Y2 were investigated. The highest throwing speed of crushed straw and lowest specific power consumption are the optimization goal. The results of optimization showed that the predict the best optimal parameters were 2000 r/min throwing blade rotational speed, 1.4 kg/s conveying volume, and 220 mm pipeline diameter, the planter achieved a throwing speed of 12.2 m/s and specific power consumption of 9179 m²/s². And then a field test verification was conducted. The planter achieved a throwing speed 12.4 m/s and specific power consumption 9070 m²/s² while selecting the best optimal parameters. Thus, the optimal parameters can provide a high-performance operation and satisfy the actual operation requirements The results provide a theoretical basis and data support for seeding technology innovation and equipment optimization to ensure uniform crushed straw throwing in dense rice stubble fields. [ABSTRACT FROM AUTHOR]

The residual agricultural plastic film in China is not easily recovered due to the thinness and poor mechanical properties of domestic films, and a large amount of plastic film remaining in farmland soil poses a great threat to soil quality and crop production. A spring-tooth residual plastic film collector (SRPFC) is widely used in domestic residual plastic film (RPF) recycling operations. However, there are two major problems in the current SRPFC: the low recovery rate of the residual film (RRRF) caused by the difficulty of film-stripping and the high impurity rate in the film (IRF). In this paper, a stripping and impurity removal device (SIRD) is designed to address the existing problems of SRPFC, which is mainly composed of film-stripping tooth plates (FTP), two wind-collecting hoods, and two centrifugal fans. The motion and force analysis of the RPF in the film-stripping process was carried out, and the arc FTP was determined to be used for film-stripping. The size parameters of the FTP were obtained by establishing the coordinate system to solve the differential equation. By comparing and analyzing the force of RPF in the airflow field of the test bench for suspension speed and the airflow field of the wind-collecting hood, the RPF equivalent particle was established. The discrete phase model (DPM) in Fluent software was used to simulate the movement of the RPF equivalent particle, and the calculated air volume range of the centrifugal fan was 5501.88~6829.92 m3/h. The effects of forward speed, rotating speed of film conveying chain harrow (FCCH), and rotating speed of the centrifugal fan on RRRF and IRF were studied by orthogonal rotary combination experiment. The test results showed that the best combination of machine operation parameters was when the forward speed was 5 km/h, the rotating speed of the FCCH was 235 r/min, and the rotating speed of the centrifugal fan was 1978 r/min. Under these conditions, the RRRF was 92.53%, and the IRF was 9.31%. Field experiments were carried out with the rounded parameters, and the average RRRF was 92.07%, and the average IRF was 9.56% under the parameter combination, indicating that the optimization scheme of the device was feasible. [ABSTRACT FROM AUTHOR]

We investigated the characteristics and mechanisms of subseasonal precipitation variability in North China during the rainy season (June–September). Two dominant intraseasonal modes with periods of 8–20 and 30–60 days were identified via spectral analysis. Together, they explain 62.8% of the total precipitation variability. Nearly all persistent heavy rainfall events in North China were observed concurrently with the enhanced positive phases of biweekly or/and 30–60-day precipitation modes. To elucidate the origins of these two intraseasonal precipitation variabilities, we performed moisture and vertical motion analyses. The moisture diagnosis results show that the anomalous lower-level southerly perturbations, which transport the background summer-mean moisture from the tropical areas toward North China, are the key process causing abundant moisture for the anomalous precipitation occurrence. The local ascending motion anomalies associated with the occurrence of intraseasonal precipitation come mainly from the anomalous vorticity advection induced by summer-mean thermal wind. Although the key processes causing the precipitation anomalies of these two intraseasonal modes are similar, the geneses and evolutions of large-scale conditions associated with them are distinct. The biweekly circulation and convective anomalies are driven by the midlatitude wave train pattern propagating southeastward across the Eurasian continent, while the 30–60-day anomalies are determined by both upper-level perturbations along 40°N and northward-propagating intraseasonal convective activities from the tropics. [ABSTRACT FROM AUTHOR]

China's cultural performance career has been developed in recent times, resulting in a large number of students embarking on the professional path of cultural performance. To reduce the teaching pressure on school teachers, dance training gradually introduces the idea of "digital dance", using sensors to monitor posture. The nonwearable monitoring method does not require contact with the subject and typically relies on images or signal waves for positioning, but it has stringent requirements for the measurement scene. On the other hand, the wearable monitoring method requires the sensor to be worn on the subject's body all the time, so it needs to be light and energy-efficient. Therefore, this paper designs and implements a set of application platforms, which parametrically analyze the dance movements, consume low energy, are lightweight, and are simple to use. For this purpose, a wearable digital dance training system based on microelectro-mechanical system (MEMS) sensors has been developed, and a solution to the challenges of teaching movement precision, scientific teaching methodologies, and early warning analysis of joint is also proposed. Firstly, the basic knowledge of human posture measurement and human model is merged to build a new modifiable human model. Secondly, the overall design of the posture data acquisition device is presented, which includes a base station and several nodes. Finally, the overall framework of the software platform is designed, which consists of client and server. The experimental results show that the system can achieve the purpose of providing teaching programs for dance students. [ABSTRACT FROM AUTHOR]

With the progress of the Internet of things technology in recent years, all aspects of people's lives have also been affected. More and more people are immersed in the virtual world and ignore the real activities. According to the survey, nearly 50% of people in China are in subhealth, mainly modern diseases caused by long-term inactivity. Therefore, to form a good habit of physical exercise, we must start from an early age. Starting from the physical education teaching in primary and secondary schools and from the perspective of modern scientific and technological facilities, this paper discusses the practical sports analysis and action optimization of physical education teaching based on the perception of the Internet of things. Starting from the practice of Internet of things sensor sensing in physical education teaching, we have successively determined the multisensor motion acquisition system algorithm, motion pattern recognition algorithm, and motion energy consumption algorithm, which provides modern equipment for motion analysis and motion optimization in physical education teaching practice, which breaks the current situation that traditional teachers spend a lot of time and energy for students. Combining sports mode with sports energy consumption can not only analyze sports data accurately and in real time but also optimize and predict students' sports behavior in time. We hope to supervise and urge primary and secondary school students to exercise through technical means to improve the quality of primary and secondary school students' exercise and improve people's health through physical exercise. [ABSTRACT FROM AUTHOR]

With the development of China's social economy, the pace of people's life is also accelerating. Therefore, in the face of the increasing pressure of life and work, people have begun to pay more and more attention to improving their physical fitness and they also pay more and more attention to sports in their spare time. The knee joint is a very important body part that will be involved in sports. Therefore, in sports, it is very important for healthy sports to pay attention to the state of the knee joint at all times and avoid injury to the knee joint during sports. The three-dimensional visual analysis of the knee joint movement trajectory in sports training refers to the trajectory capture and three-dimensional visual analysis of the knee joint movement in sports training based on the computer-based description and understanding of model technology. The three-dimensional visual analysis of the motion trajectory of the knee joint in sports training is conducive to the attention and analysis of the motion state of the knee joint in sports training, so as to help find problems and avoid knee joint damage during sports training as much as possible. This paper aims to study the 3D visualization analysis of knee joint motion trajectory in sports training based on digital twin and establish a 3D visualization system of knee joint motion trajectory based on digital twin technology, and based on this system, the three-dimensional visualization experiment of knee joint movement trajectory in sports training is carried out. The experiment concluded that the signal-to-noise ratio of the three-dimensional visualization image of the knee joint movement trajectory in sports training based on the three-dimensional visualization system established by the digital twin is 68% and the clarity is 89%. It shows that the system has a good 3D visualization effect. [ABSTRACT FROM AUTHOR]

Ramie is an important cash crop in China, and ramie fiber is an important raw material for the textile industry. As a shrub plant, the spatial distribution of the ramie plant is different from that of herbaceous crops, and its plant spacing and row spacing are not fixed, which affects the cutting operation during harvest. In order to solve the above problems, this study constructed a ramie spatial distribution model with statistical methods, and built a prediction model of ramie harvesting feeding quantity on this basis. Based on the analysis of the absolute motion trail of the ramie harvester cutting knife, the calculation equation of the missing cutting area was established, and then the prediction model of the mis-cutting rate was obtained. The results of the ramie field harvest showed that the prediction model of the feed quantity and mis-cutting rate was effective. These methods can provide references to the control and optimization of ramie harvester parameters. [ABSTRACT FROM AUTHOR]

This study determined the acute changes in kinematics and kinetics when an additional load equivalent to 5% body mass was attached to the torso during change of direction (COD). In this within-subject repeated measures study, 14 male soccer players (age: 18.29 ± 0.32 years) volunteered to participate. Subjects performed COD under two conditions in randomized order: (1) no WR, and (2) with WR. No significant differences between the loaded and unloaded conditions in actual COD angle, approach speed, braking time, propulsive time, contact time, COD completion time (all p > 0.05, ES = 0.05–0.11), and all measured kinematic parameters (all p > 0.05, ES = 0–0.18). Nonetheless, ankle plantar/dorsi flexion ROM had possibly small increase in the loaded condition (ES = 0.24). Kinetics analysis has shown that the loaded condition was likely to have small increase in relative peak vertical propulsive ground reaction force (GRF, p = 0.11, ES = 0.41), and possible small increases in relative peak braking GRF (vertical: p = 0.21, ES = 0.42; total: p = 0.22, ES = 0.38), relative peak total propulsive GRF (p = 0.24, ES = 0.26), and relative braking impulse (horizontal, vertical, and total; p = 0.27–0.41, ES = 0.26–0.28). WR did not significantly change the acute movement techniques, meanwhile induced small increases in important kinetic stimuli for potential adaptation in COD. [ABSTRACT FROM AUTHOR]

The usage of film mulch cultivation technology is ever increasing in China, particularly ranging from fruits and vegetables to a variety of food crops in a large area. Ultra-thin plastic film is commonly used as a soil surface mulch. The long-term laying of plastic film has brought serious mulch residues, due to its polyethylene film is difficult to be degraded in the natural environment. The accumulation of plastic film residues has caused serious negative effects on the crop growth, such as microorganisms in the soil difficult to survive, damage of soil agglomeration structure, obstruction of moisture circulation, soil salinization and compaction. As such, various machines were developed for residual film recovery, with strong adaptability, high recovery rate, and high work efficiency, particularly on the residual film pickup device in tooth-chain type for gathering and tying the film. However, the complicated structure of mechanism limited the application of residual film pickup device. At present, a bent conveyor chain is often used, in order to improve the efficiency of removed film. If the length beyond the critical after the conveyor chain bending, the film pickup teeth are easy to be deformed after impact, resulting in leakage pickup phenomenon, and the incompletely removed film, easy to wind, and low loading. This study aims at the problems of missing inspection, incomplete stripping, and winding of rake type residual plastic film collector during the working process, thereby to design a guiding chain harrow type residual plastic film collector on the surface soil. The main content included the design of guide chain harrow type picking-up film mechanism, and the connection structure between the rake assembly and the transport chain, with emphasis on the transport chain for the removal of film. Specifically, the structure of rake teeth and the arrangement of rake teeth were determined, the rotary film removal device with guide rake to improve the effect of removing film, and a pushing film mechanism was designed at the rear of film collecting box for increasing the loading capacity. A combined method of mechanical and hydraulic pressure was applied to realize the transmission requirements of picking up, removing, and pushing film. A motion analysis and pretests were conducted to optimize the structural parameters of main moving parts. A quasi-horizontal orthogonal test was carried out to verify the reliability of key parts in the machine and the operation performance. The test factors were selected, including the machine advancing velocity, the depth of rake into soil, and the chain rake input speed, and the indexes were the film pickup rate and film winding rate. The results show that the primary and secondary factors that affected the film pickup rate were the chain harrow input speed, the machine advancing velocity, and the depth of rake into soil, whereas, the primary and secondary factors that affected the film winding rate were the chain rake input speed, the depth of rake into soil, and the machine advancing velocity. Taking the film pickup rate as the main index, the integrated balance method was used to determine the optimal operating parameters, where the machine advancing velocity was 8 km/h, depth of rake into soil was 30 mm, and the chain rake input speed was 143 r/min. A field validation test was performed on the better parameter combination, where the film pickup rate was 88.73%, and the film wrapping rate was 1.91%. The findings can provide a sound reference to optimize the design of residual plastic film collector, and further to improve the operation performance. [ABSTRACT FROM AUTHOR]

In the practical engineering applications of multi-body floating wave energy converter (WEC), the traditional geometric optimization is always expensive and time-consuming. This study aim to propose a more efficient geometry optimization strategy with a hinged double-body floating WEC as the study object. The influences of geometric parameters of the buoys on the pitching motion and energy conversion ability are analyzed by numerical simulation. Simulation results show that the resonance state of the pitching motion of the buoys mainly depends on their radius and draft rather than the length; But the length of the buoys, rather than the radius and draft, always has a significant effect on the pitching phase difference of the adjacent buoys. Based on the motion analysis and resonance response, an efficient multi-factor geometry optimization strategy is put forwarded. By the strategy, the sub-optimal and optimal geometrical parameters are solved out quickly at several typical wave conditions of China Seas. The results indicate that the optimal total length of WEC is approximately equal to the wave length. The optimal diameter of buoys is about 25% of the length of buoys. And the optimal draft should attain about 61% of the diameter. [ABSTRACT FROM AUTHOR]

A large amount of maize stalks are produced each year, due to the maize is serving as one of the main grain crop in China. Maize straw retention to the field after chopped is widely used in most disposal approaches. However, the currently used single shaft maize stalk chopping and retention machine can not meet the quality requirements of stalk chopping, such as too long maize stalk after chopping, and the low chopping pass rate of maize stalk, particularly when the amount of maize stalk was large, while the scarf skin of maize stalk was toughness. The shortcoming of maize stalk chopping directly determines the next seeding production, seed germination, and final crop yield. This paper aims to propose a novel chopping method, and thereby to design a double rollers type stalk chopping and retention device with different rotation speed and dynamic double support. The device mainly included the shell, supporting plate, suspension device, gearbox, transmission, chopping and collecting blade, shaft of chopping, collecting blade, blade shaft of slide-cutting supporting blade, and slide-cutting supporting blade. In operation, the chopping and collecting blade with anticlockwise rotation, firstly collected and chopped maize stalk in the field; then the maize stalk was chopped in dynamic support of side-cutting supporting blade with same rotation direction of chopping and collecting blade. A mechanical analysis of maize stalk was conducted under the effect of chopping and collecting blade, as well the slide-cutting supporting blade. The results showed that the rotation speed of chopping and collecting blade, and the slide-cutting angle of slide-cutting supporting blade were the main factors to affect the stalk chopping process. Furthermore, a motion analysis of chopping and collecting blade was carried out, including two L-type blades and a straight blade. The results revealed that the bend angle and length along the cutting-edge of L-type blade, and the rotation speed of chopping and collecting blade, were the main factors to affect the unpicking rate of maize stalk, and chopping pass rate, when the number of chopping and collecting blade and operation speed of device were fixed. In the slide-cutting supporting blade, the cutting-edge curvilinear equation was in the form of the logarithmic spiral equation. Moreover, the range of slide-cutting angle was 30º-60º, due to the slide-cutting angle can be more than frictional angle between maize stalk and slide-cutting supporting blade, according to slide-cutting principle. Importantly, the cutting edge of slide-cutting supporting blade with sawtooth was designed to increase the fraction of maize stalk and slide-cutting supporting blade. Prior to accurately coordinating between chopping and collecting blade, and side-cutting supporting blade, the rotating speed range of chopping and collecting blade was determined as 1 150 -2 500 r/min, to ensure the high stalk chopping pass rate. The rotation speed of slide-cutting supporting blade was one half that of chopping and collecting blade, to guarantee the speed of backward spread of chopped maize stalk. Simultaneously, the chopping and collecting blade, and side-cutting supporting blade, both were double helix arrangement to reduce machinery vibration, while increase machinery life. One device was installed 20 chopping and collecting blades, and 40 slide-cutting supporting blades. A quadratic rotation orthogonal combination test was used in the field research, to obtain the optimal structure parameters, where the chopping pass rate of maize stalk was set as test index. Some test factors were selected, including the cutting-edge bend angle of L-type blade (20º ≤γ≤60º), and cutting-edge length of L-type blade (30 mm ≤k≤60 mm), rotation speed of chopping and collecting blade (1200 r/min≤nY≤2 000 r/min), and slide-cutting angle of slide-cutting supporting blade (30°≤τ≤60°). The Design-Expert 8.0.6 software was applied to analyze the double factors interaction on stalk chopping pass rate, thereby to obtain the regression model between test factors and index. The primary and secondary factors that affect the maize stalk chopping pass rate were the rotation speed of chopping and collecting blade, the length of cutting-edge bend angle, the cutting-edge length of L-type blade, and the slide-cutting angle. In multiple objective optimization, the optimum ranges can be achieved, including the cutting-edge bend angle of L-type blade (41º≤γ≤57.64º), the cutting-edge length of L-type blade (41.7 mm≤k≤51.71 mm), the rotation speed of chopping and collecting blade (1 657.37 r/min≤nY≤1 889.97 r/min), and slide-cutting angle of slide-cutting supporting blade (36.55º ≤τ≤ 49.08º). In the field test, the rotation speed of chopping and collecting blade, the length of cutting-edge bend angle, and cutting-edge length of L-type blade, and slide-cutting angle were set as 1700 r/min, 40º, 45mm, and 45º, respectively. The field test results demonstrated that the maize stalk chopping pass rate was 92.58% under the optimal working parameters, while the error with the predictive value (93.96%) was less than 5%, indicating the reliable optimization of parameters. The finding can offer a sound reference to improve the chopping quality of maize stalk in the chopping and retention machine. [ABSTRACT FROM AUTHOR]

There is a certain correlation between human health and actual exercise. This has always been one of the focuses of many scholars. When analyzing the movement of human body, a lot of modern technology and equipment need to be used. In order to better realize the physical health of young people in our country, the health service system based on sensor technology has been put forward. By introducing accelerometer technology, real-time data capture and analysis of human motion posture and movement trajectory were carried out. At the same time, the reliability of the algorithm was improved. In order to verify the feasibility of the method, a practical case was verified. Experimental results showed that the method was more scientific and reasonable in motion capture analysis. [ABSTRACT FROM AUTHOR]

The OpenFOAM was extended to analyze the roll motion of an immersed tunnel element excited by outside waves and inside ballast water sloshing. The reliability of our numerical model was validated by comparing the results with related experimental tests. Then, the effect of filling depths of ballast water on damping roll motion of a 2-D tunnel cross-section excited by regular waves was analyzed, and the effect of tank width with constant filling weight on rigid-fluid coupling was also discussed. Results revealed that a crucial filling depth for best damping performance on roll motion of liquid-carrying structures exists between the dry condition and the filling depth corresponding to the most severe resonance condition. For the application of the tunnel element in this study, a dimensionless filling depth of 0.1 shows the best damping effect. Furthermore, for different tank widths with a constant filling weight, the damping effect of the ballast water is mainly dominated by the natural frequency of ballast water and has a negative correlation with the natural frequency, for small natural frequency of large tank width, the phase lag between roll motion and sloshing moment gets closer to the maximum damping lag of π/2 due to violent sloshing flow. • An improved numerical model based on OpenFOAM for investigating the roll motion of a 2-D cross-section of immersed tunnel element excited by the regular waves and ballast water sloshing was developed. • This study is conducted based on the parameters of immersed tunnel element used in Hong Kong–Zhuhai–Macao Bridge (HZMB) in China. • The sloshing and wave forces are obtained to analyze their contribution to tunnel motion and for a beneficial analysis on the fluid-tunnel coupling mechanism. • The crucial filling depth in damping the maximum tunnel motion for different waves has been investigated in detail, and the effect of tank width with a constant filling weight on damping performance is also discussed. [ABSTRACT FROM AUTHOR]

Human behavior analysis is an important area of research in computer vision and is also driven by a wide spectrum of applications, such as smart video surveillance and human-computer interface. In this paper, we present a novel approach for human behavior analysis. Two research challenges, motion representation and behavior recognition, are addressed. A novel motion descriptor, which is an improved feature based on optical flow, is proposed for motion representation. Optical flow is improved with a motion filter, and feature fusion with the shape and trajectory information. To recognize the behavior, the support vector machine is employed to train the classifier where the concatenation of histograms is formed as the input features. Experimental results on the Weizmann behavior database and the Institute of Automation, Chinese Academy of Science real- world multiview behavior database demonstrate the robustness and effectiveness of our method. [ABSTRACT FROM AUTHOR]

In recent years, research into and development of hillside tractors has become a popular topic in the field of agricultural engineering in China. To solve the main problems associated with a low adjustment range of the working speed, complex operation, and low safety for slope operation of medium-sized crawler tractors, a hydrostatic drive system that can be used for hillside crawler tractors was designed. According to the operation requirements of a hillside crawler tractor, the parameters of the three-cylinder diesel engine, hydrostatic transmission (HST), drive rear axle, and other key components of the drive system were matched after the force and motion analyses of the tractor, and then the main performance indicators, including the traction performance, system pressure and working speed of the drive system were verified. On this basis, a drive system performance test bench was built, and the traction performance and starting acceleration performance of the drive system was tested. The results of the traction bench test show that when the engine was at the maximum torque point of 1700 r/min, the maximum theoretical tractive force outputted by the tractor in Gear I was 114,563 N, and the maximum theoretical tractive force outputted by tractor in Gear II was 10,959.2 N, which were both larger than the traction resistance of 9550.6 N experienced by the hillside tractor ploughing on the slope. The results of the initial acceleration bench test show that the tractor driving speed can gradually increase with increasing output of the variable pump and can reach the maximum in 3 s. When the tractor was driving on flat ground, the maximum driving speeds of Gear I, Gear II, and Gear III were 4.65 km/h, 6.58 km/h, and 8.57 km/h, respectively, which are close to the theoretical values. When the tractor was driving on a 15° slope, the maximum driving speeds of Gear I, Gear II, and Gear III were 4.55 km/h, 6.25 km/h, and 8.28 km/h, respectively. It can be concluded that the design matching of the drive system is reasonable, the speed consistency is good and there is enough power reserve, which can meet the requirements for a large workload. [ABSTRACT FROM AUTHOR]

Normative tibiofemoral data of Chinese or Asian subjects during gait is rarely reported. This study is aimed at investigating the six-degree-of-freedom (6DOF) knee kinematics of adult Chinese during gait, based on a novel portable system. Twenty-eight healthy Chinese subjects (56 knees) were studied during their treadmill gaits. A set of optical marker clusters were attached to the thighs and shanks of each subject, who was tracked by an optical joint kinematics measurement system. Knee landmarks were initially digitized with respect to the marker cluster sets to determine the local coordinate systems for calculation of 6DOF knee joint kinematics. The range of motion (ROM) in 6DOF and 5 kinematic parameters were calculated and compared between bilateral knees and genders. We discovered that knee rotations, as well as motion in proximodistal and mediolateral translations, showed similar patterns in flexion and extension. However, the anteroposterior translations did not show a clear pattern. The results of ROM in 6DOF obtained in this study are comparable with those reported in existing literature. No statistical difference was found between left and right knees either in the ROMs or in the 5 kinematic parameters. However, the ROM in the mediolateral direction during gait was found to be higher in men than women (P=0.014). In addition, the femurs of female subjects rotated more internally than the femurs of male during the stance phase (P=0.011). We concluded that normal Chinese knees exhibited distinct gait patterns, except for anteroposterior motion. Women and men exhibit different axial rotations and mediolateral translation patterns during their treadmill gait., (Copyright © 2015 Elsevier B.V. All rights reserved.)