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Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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 Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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 Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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 Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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 Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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 Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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 Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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.)

Unmanned Aerial Vehicles (UAV) have widely been served as a new technology in agricultural aviation plant protection and pest control in China. However, it is highly demanded to improve the accuracy of UAV spraying pesticides and operational efficiency. In this study, a Variable Rate Application (VRA) of a centrifugal spraying system was designed for precise placement and timing of pesticide application in specific field conditions using the network Real-Time Kinematic (RTK) technology. STM32F103 single-chip microcomputer was used for the core controller. A serial port of controller was selected to obtain the global position system (GPS) information. A network modular Data Terminal Unit (DTU) was connected to realize the network RTK technology via the serial port of the controller. The control voltage was used to tailor the speeds of the centrifugal nozzle motor and peristaltic pump. A Pulse Width Modulation (PWM) was used to control the output voltage from the core controller to the armature of motors in this system. The speed of the centrifugal nozzle motor determined the output droplet size, while the speed of peristaltic pump determined the flow rate and amount of spray fog. The agricultural dataset before the system working was acquired using the airborne multispectral camera, ground object spectrometer, and handheld GPS. A prescription chart was also constructed using ArcGIS software. In the system working, the GPS modular was used to capture the location longitude and latitude data for the system to read and analyze. The system was always real-time searching the UAV geographical position during the spraying pesticides process using the GPS data, and then matching the position using the orthogonal grid. Meanwhile, the system was used to real-time tailor the changes in the duty cycle of output PWM, after matching the decision of the prescription map. The speeds of the centrifugal nozzle motor and the peristaltic pump were then to control the particle size and application amount of the UAV. The operation data was finally uploaded to the monitoring platform for real-time display and storage. Several spraying experiments were carried out in the research base of South China Agricultural University in Zengcheng City, Guangdong Province of China. The airborne spraying device was carried on the MG-1p plant protection UAV using a developed DJI Drone. The sampling points of droplets were set to match the planting density of crops, where the water-sensitive paper was used to collect the droplet data. After UAV operation, the water sensitive paper was collected into a plastic bag for later use. An hp4678 scanner was selected to map the collected water-sensitive paper after the experiment. A DepositScan software was utilized to analyze the water-sensitive paper in each sampling area after image acquisition. A detailed dataset was obtained, including the deposition amount, coverage density, and particle size of droplets. The data demonstrated that the accuracy of the device was within 0.6 m at the operating speed of 2 m/s. The application effect was finally stabilized within 2.2 m in the case of continuous operation. Particle size varied smoothly in the boundary area of prescription, as the rotating speed of the centrifugal nozzle increased. The findings can provide a sound basis for the improvement of variable application technology of plant protection UAV in precise agriculture. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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.)

Rational construction of a well-facilitated farmland become necessary for food security and modern agriculture in China. In farmland construction, the automatic management of spatial data can benefit to accurately distinguish well-facilitated farmland from the various land types. Various discriminating ways of well-facilitated farmland are adopted due to the different influence factors of agricultural production in in different regions, where the spatial distribution and structural features of well-facilitated farmland are quite different from place to place across the country. Most of the previous studies focus mainly on policies, benefit evaluation, preliminary planning and design in the well-facilitated farmland construction. There is still lacking on the studies of the discrimination and analysis for the regional structural features of the well-facilitated farmland. In this paper, a framework of an index system was constructed to identify the spatial distribution and structural features of the well-facilitated farmland using the law of spatial differentiation together with the related national standards and strategic planning, ranging from the scale and shape of farmlands, irrigation and drainage facilities, traffic accessibility, and farmland protection ratio. The identifying system was designed on the basis of the index framework with C#. NET and Arc Object. Subsequently, the proposed system was verified for its availability by taking a case study of a Loess Plateau and a southern mountainous region. The results were as follows: (1) In the Loess Plateau area, the standard rate of the farmland scale, farmland shape, irrigation and drainage facilities, traffic accessibility was 87.01%, 83.12%, 80.52%, 90.91% and 83.12%, respectively. The well-facilitated farmland area can be identified by the system was 38.33 hm² with the total discriminating precision was 94.38%. There were some farmlands that did not meet the requirements of the well-facilitated farmland, such as incomplete irrigation and drainage facilities, the irregular shapes of the fields that distributed in the branch furrow and furrow head around the farmland. (2) In the southern mountainous area, the standard rate of all spatial features was 100%. The well-facilitated farmland area that identified by the system was 30.07 hm², which was 10.34 hm² higher than that of the state-approved well-facilitated farmland. The high identified areas can be because some fields that meet the requirements of well-facilitated farmland have not been classed as the permanent basic farmland in some administrative regions. When regardless of this classification, the total discrimination precision was 100%. This index system can be used in different scenarios, such as macro monitoring and evaluation, project design and inspection of the well-facilitated farmland. This system was also applied for the Northeast Plain, North China Plain, Loess Plateau and southern mountainous regions, while the key elements of the spatial features of well-facilitated farmland construction can be detected with a reliable discriminant resolution. When combining with the remote sensing technology, the index system can help automatic management to know the real-time spatial data of well-facilitated farmland construction. Therefore, the developed system can be successfully applied to identify the extract well-facilitated farmland in the construction area, and then to analyze the obtained spatial data in real time, finally to implement automatic management for well-facilitated farmland construction. Furthermore, the proposed system in this paper can offer a promising reference to the current comprehensive supervision platform, and improve the management effectiveness of well-facilitated farmland construction in modern agriculture. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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 Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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.)

As long-standing goals and all-round development practices of agricultural and rural modernization of China, the rural revitalization strategy provides huge opportunities and spaces for the disciplinary innovation and development of all agricultural related disciplines. The purpose of this paper was aimed to analyze special requirements, objectives, tasks and implementation environment raised by the rural revitalization strategy, based on reviewing the references and development history of agricultural engineering, and to analyze impacts of the rural revitalization strategies on and demand for the adjustment of agricultural engineering innovation, so that to figure out the ways, means and measures for new round disciplinary adjustments and restructuring of agricultural engineering. In recent years, the disciplinary renovation and restructuring for all subjects have been encouraged and launched by the Ministry of Education, China. The new round adjustment of the discipline layout marked by the innovation and construction of new disciplines such as new engineering and new agriculture were given more attention on introducing new technological and industrial revolution achievements, and transforming and upgrading traditional engineering and agricultural science with information technology, digital technology and artificial intelligence. But it’s worth noting that insufficient attention had been paid to the expansion of agricultural and rural modernization roads and changes in development patterns caused by the rural revitalization in this important adjustment process. Agricultural engineering takes multiple and wide range responsibilities in offering scientific and technological support and talent training and cultivation, so that it plays a special and key role in the modernization of agricultural and rural areas. Information, communication, intelligent and smart technologies, and all new breaking through technologies should be introduced into agricultural engineering to equip and empower it more updated and effectively. Under such a background, more efforts should also be made in such important development consequences brought by the rural revitalization strategy. The disciplinary adjustment of agricultural engineering should be restructured and optimized according to the instructions of the national development strategies and its new application areas required by agricultural and rural modernization. The more attention should be paid to the influence of social and economic development mode and structural adjustment and upgrading on innovation and its correspondence. Great attentions should be paid to following key issues: 1) The implementation of the rural revitalization strategy has opened up some new development spaces for the disciplinary innovation of agricultural engineering and proposed new development requirements. 2) The development and extension of the agricultural engineering technology systems will extend from the agricultural production to rural multi-industrial integration, relying on all agricultural and rural resources. 3) The cultivation of agricultural engineering talents and the construction of educational scientific research systems should aim at the requirements of the whole process for all rural productions, as well for the construction of rural ecological systems. 4) The systematic construction and management of agricultural and rural industries in different regions should meet the needs of the urban-rural integration development and the modernization of new rural communities’ governance system. Currently, more reform, renovations and adjustments should be made to reshape the agricultural engineering to meet new needs of the rural revitalization, the new development fields and directions of agricultural engineering disciplinary innovation currently are more practical in rural e-commerce engineering, rural landscape construction and maintenance engineering, rural new industrial development space construction, rural ecological environment engineering, and rural social and economic management and governance system engineering. [ABSTRACT FROM AUTHOR]

In order to extract the features of fault signals of dynamic system polluted and modulated by background noise, and solve anomaly detection problem of slight fault based on the generated normal patterns, this paper considers the one-class classification problem of insufficient fault samples and class imbalanced in intelligent monitoring and diagnosis for dynamic systems. Besides, it is well known that the conventional feature selection methods always depend on specific fault types. If some features are chosen to identify one fault, their performance may be poor for other fault cases. Compared with other classifiers, support vector data description (SVDD) is only based on samples at normal state, and its optimization hyperplane is independent of specific fault types. Chaos and fractal are the nonlinear phenomena which widely exist in nature and socio-economic system. Chaos and fractal can help to find out the internal regularity of system, and it is a new branch and the important fields of nonlinear science, whose subjects include unsmoothed, nondifferentiable geometry and long-range correlated structure in nonlinear system, method to judge if one system has chaos and fractal phenomena that mainly uses the largest Lyapunov index and fractal dimension to judge. Study has showed that the chaos and fractal theory can reflect the essence of the dynamic systems as complex system. Hence, a new abnormal identification and feature selection method of dynamic systems that combines chaos fractal feature and SVDD is presented. In this method, the receiver operating characteristic (ROC) curve for 2 classifying errors i.e. misdiagnosis and missed diagnosis in classification field based on SVDD is synthesized in the proposed method to make the selected chaos fractal and features more effective. The best combination of the largest Lyapunov exponent and correlation dimension is selected through analyzing chaos and fractal features, which include: the largest Lyapunov exponent, box dimension, correlation dimension and the mean of generalized dimension. To ensure good performance in the environment of complex dynamic systems, anti-noise robustness analysis is conducted. The data samples of different normal states are trained to obtain the optimal enclosing spheres respectively. And the relative distances between diagnostic samples and the distributed spheres are introduced to decide which class they belongs to. In this way SVDD classifier of normal condition samples has been proposed based on combined features as the input of SVDD classifier. In addition, SVDD is a robust data domain description method; its performance, however, is strongly influenced by kernel parameter. To improve the low fraction of target class that is accepted by the SVDD in the case of atypical target training data, experimental studies for seeking optimum parameters of kernel functions which are used to improve classification precision have been discussed. The penalty coefficient B is fixed to the value of 0.4, and in this case, the optimal kernel parameter value is suggested as a value of 0.6, which can prevent effectively the phenomenon of over-fitting and has good fault sensitivity and generalization. Abnormal identification model is set up based on the normal history data of the system to detect the abnormal condition by comparing the projection on the chaos fractal feature space to which the real measurement data and normal data were projected. Using SVDD-ROC as feature extraction method, the problem that traditional feature extraction methods depend on specific fault samples is avoided. The experiments with single-point fault data simulated on bearing vibration test-bed have been implemented to evaluate the efficiency and performance of the clustering, and results of test show that the proposed method only requires the samples at normal state to identify condition between normal states and fault states, and it is able to well distinguish unknown fault types. The study can provide theoretical and design basis for the modeling and detecting of dynamic systems with fault conditions, which is helpful to prevent incident, save maintenance cost, improve the utilization rate of the system, protect the running of production, and thus reduce costs. [ABSTRACT FROM AUTHOR]

The articulated frame steering vehicles (ASV) are widely implemented in agriculture, mining, construction and forestry sectors due to their high maneuverability. The ASVs, however, are known to possess lower dynamic stability and yield high magnitude of whole-body vibration, which are reported to be harmful to the operators. Automatic driving system is thus necessary for the ASVs to exclude the human driver from detrimental operations, especially for the agricultural ASV. In order to enable the automation of ASV, path tracking strategies are essential to maintain the normal work of the vehicles. As the ASV dynamics significantly are different from the conventional vehicles with front wheel steering, the path tracking controller derived for conventional vehicles is considered not to be applicable for the ASVs. Moreover, large variations of the vehicle load and the off-road excisions challenge the robustness of path tracking algorithms. In this paper, a path tracking strategy is proposed for the ASVs on the basis of sliding mode control (SMC). The kinematic model of the ASV is derived neglecting the vehicle dynamics. Three measurable errors are defined to indicate the deviation of real path from reference path, i.e. lateral displacement error, orientation error and curvature error. These errors serve as the inputs in order to synthesize the SMC. The exponential reaching law is selected in order to increase the reaching speed and reduce chattering. The sign function of exponential reaching law is replaced by a continuous function to further suppress the chattering. Lyapunov function is then utilized in order to assess the system stability. The system transition performances in terms of response time, setting time and overshooting are tuned via pole placement method. The differential transformation method is implemented to determine the poles, in order to obtain the transition performances while preserving the system stability. Ackermann's formula is used to improve traditional pole placement algorithm and further design the control law. The open loop eigen-polynomial of the system is thus not requisite. Furthermore, the hardware-in-the-loop (HIL) simulation is conducted to evaluate real-time performance of the proposed control law. The HIL platform is set up on the basis of national instruments PXI-8110 and CRIO-9024 as well as a host computer. The real-time ASV kinematic model established in the MapleSim platform is downloaded into the PXI-8110 as the simulation plant, and the SMC path tracking algorithm compiled by Simulink is embedded to the cRIO-9024 as the real electronic control unit. The host computer couples the real-time vehicle model and the path tracking algorithm via the LabVIEW platform and displays the simulation status as the upper monitor. The path tracking algorithm then controls the vehicle to follow a circle path in real time. The results suggest that the simulated vehicle path is smooth and almost identical to the reference path. The 3 kinds of errors achieve steady state in 10 s. The proposed SMC controller is then demonstrated to be robust even neglecting the vehicle dynamics. The results also suggest that the SMC with Ackermann's formula can fulfill the prescribed request of the dynamic and the steady performance. The real-time performance of the path-tracking is even better than the off-line simulation. The simulation duration 60 s is equal to the calculating duration in the HIL simulation that means the time is synchronous. Compared with the real vehicle test, the HIL simulation is economical and efficient. This research can provide a reference for the design of agricultural ASV automatic driving system. [ABSTRACT FROM AUTHOR]

At present, most combine harvesters are using Global Positioning System (GPS) to get the position of harvesters and draw harvesters' work trajectories. However, the positioning information might be instable by using a single positioning. In order to solve this problem, this paper makes full use of Beidou/GPS dual-mode receiver which supports positioning and two-way communication. The inside of the Beidou/GPS dual-mode receiver contains 2 positioning systems: Beidou Navigation Satellite System (BDS) and GPS. But these 2 positioning algorithms are using 2 different coordinate systems: Beidou navigation positioning algorithm uses BJ-54 coordinate system, and the positioning algorithm of GPS navigation uses WGS-84 coordinate system. Complementary use of these 2 positioning systems can solve the problem of positioning information instability that occurs when using a single positioning. It means that when the Beidou positioning information has deviation, GPS positioning information can be used to make correction. The combine harvester walking map can be drawn from the positioning information of the Beidou/GPS dual-mode receiver. The message communication function of Beidou satellite is used instead of GSM short message service to realize remote transmission between harvester and control center. The integrated management system for grain combine harvester is designed using sensor detection technology, data acquisition and processing technology, wireless communication technology, navigation technology, speech synthesis technology and computer network technology. The integrated management system of grain combine harvester includes 2 parts: Vehicle subsystems and control center. The vehicle subsystem consists of Beidou/GPS dual-mode receiver, weight sensor module, moisture sensor module, speed sensor module and text-to-speech (TTS) module. The control center consists of clients and server. The vehicle subsystem collects the data of geographical position, harvested area and grain weight, and then transmits the data to the control center by Beidou satellite. The server of control center analyzes and processes these data, and then draws the harvester's work trajectory map and the yield map, and the clients of control center can query the harvester's work trajectory map and the yield map of designated position. In order to achieve integrated management and scheduling for harvesters, the control center can send text commands to the harvesters, and the text commands can be converted into speech through TTS technology. In the field tests, the harvester runs with the speed of 3.6 km/h. The actual area of the harvesting is about 4 716 m², the actual total mass of grain is 3 086 kg, and the average yield is 6 544 kg/hm². However, the harvesting area is 4 853 m², the total mass of grain is 3 193 kg and the average yield is 6 579 kg/hm² measured by the system. The relative errors are 2.9%, 3.47% and 0.55% respectively. From the result we find that this integrated management system of grain combine harvester has a certain error, but the precisions of harvesting area and grain weight both reach 96%. The tests show the system is running stably and reliably. Therefore, this system is valuable for yield monitoring and trans-regional operation management of grain combine harvester in southern hilly area of China. [ABSTRACT FROM AUTHOR]

The informatization trend of irrigation area is to master real time hydraulic characteristics of canal sections based on which water distribution can be realized through controlling the gates automatically. In order to serve the information construction of the Shitouhe irrigation area, in this paper, we simulated and analyzed the canal flow and gate opening characteristics with the theory of unsteady flow and automation under different conditions along the 10 km long first reach of east main canal in the Shitouhe irrigation area. In the process of analysis, first of all, the whole canal was divided into several sections, and the sections were numbered from upstream to downstream; then the error of water depth between measured and calculated accordingly was minimized, which was used as the objective function for finding the roughness based on the calculation principle of the water surface curve of the open-channel constant gradual flow; at last we simulated and analyzed the canal flow and gate opening characteristics using different schemes under different boundary conditions and roughness coefficients obtained above. In terms of hydraulic response characteristics analysis under different conditions at canal head, 3 schemes were assumed, which were as follows: Scheme 1, the flow at canal head increased from 3.5 to 11.5 m³/s within 1, 10, 30 and 60 minutes respectively and then remained unchanged Scheme 2, the flow at canal head increased linearly from 3.5 to 5.5, 7.5, 9.5 and 11.5 m³/s within 10 minutes and then remained unchanged; Scheme 3: the flow at canal head varied following the sine curve within 60 minutes and after that remained at 3.5 m³/s unchanged with the maximum variation of 2.5 m³/s. In terms of hydraulic response characteristics analysis under canal water-intake flow, 2 schemes were assumed, and based on these schemes the solutions were: Scheme 1, canal head flow was stable at 3.5, 5.5, 7.5, 9.5 and 11.5 m³/s respectively, and at water intake of No.1 branch (at Section 72) take water according to design flow of 1.03 m³/s; Scheme 2, canal flow was stable at 11.5 m³/s, and at water intake of No.1 branch (Section 72) take water of 0.1, 0.2, 0.4, 0.6, 0.8 and 1.03 m³/s respectively. In terms of hydraulic response characteristics analysis of gate control, 2 schemes were assumed, based on which the solutions were: Scheme 1, the flow at canal head was stable at 11.5 m³/s, and at water intake of No.2 branch take water of 2.5 m³/s under gate control; Scheme 2, the flow at canal head was stable at 11.5 m³/s, at water intake of No.2 branch take water of 2.5 m³/s, and after 2.5 h at water intake of main 7 lateral take water of 0.2 m³/s. Through simulation and analyzation under the different conditions, the hydraulic response characteristics of the canal flow were got as follows: 1) When canal head flow changed, the flow would be changed later with the farther distance from the canal head, and flow along longitudinal direction would be flattened. 2) Under the same flow change rate, the time between starting to change and recovering to be steady would be longer when the distance from canal head was farther, but under different flow change rates, when the flow change rate was larger, the time between starting to change and recovering to be steady would be shorter at the same distance from the canal head. 3) Under different flow rate conditions at canal head, when canal intake flows were the same, the steady flow size exhibited a linear relation with the influence distance of intake flow on upstream stream; but when canal intake flows were different, the steady flow size exhibited an exponential relationship with the influence distance of intake flow on upstream stream. 4) Under steady flow condition at canal head, when individual intake gate was controlled and its opening operates frequently during initial period; when some intake gates were controlled, the opening of any intake gate would affect intake flows of the others, due to the intake flows' reciprocity. 5) By comparison, the simulated hydraulic response characteristics at canal sections were consistent with the measured ones, and the error of canal water depth was within ±10 cm. These may provide some basic knowledge for the safety operation in order to realize scientific allocation of water resources in an irrigation area. [ABSTRACT FROM AUTHOR]

The service value of agro-ecosystem is closely related with other product production. The ecosystem can provide service value, which is usually considered as the substitute of purchasing input, in order to benefit the cost reduction. There is dynamic equilibrium between agricultural ecosystem protection and grain output increase, and they have the "falling" relation. In order to maximize profits at the level of land utilization, higher dependence of agricultural producers on ecosystem service will reduce farmland output. In this paper, the production function model of agricultural ecosystem is built so as to reasonably determine the alternative conditions and output results, and quantitative research of allocation proportion between the land reserved and the land providing ecosystem service is conducted. Taking the upstream of Yongding River basin as the study region, the calculation is conducted by means of the elasticity in land yield for production. If the land providing the ecosystem service in the river basin is increased by 1%, the corresponding crop output will be reduced by 2.7%. The quantitative analysis model is given from the micro-level perspective of the "falling" influence of agricultural ecological value, but the research in the influence on environmental protection policies in production shall be strengthened. While there are certainly instances that the interests of agro-ecosystem production and conservation may be aligned, such "win-win" outcomes are typically limited to a certain range of the production vs. conservation space. As literature analysis, some other authors have noted that the characteristic of the interaction between natural and purchased inputs may have important implications for agro-ecosystem conservation policy. The ecosystem services' value often rests on "natural" inputs; when the price of purchased inputs goes up, more land will be conserved to provide ecosystem services. In agro-ecosystems, the changes in the land for planting may also have a dynamic feedback effect on the incentive prices, and the agriculture incentives influence the ecosystem services through motivating the changes in land use and management. Co-benefits and trade-offs can occur over multiple spatial and temporal scales. A typical "falling" in agro-ecosystems is the function of supporting, regulating, habitat and cultural services provided by natural ecosystems, which are substituted for food, fiber and livestock products. This reduction in output will be translated into an increase in agricultural products' prices, as well as greater pressure to produce in other places, as a result, reducing the incentives for other producers to rely more heavily on the ecosystem services in production. At present, the incentives such as payments for ecosystem services are increasingly used to rebalance the supply of non-marketed services. Agro-ecological compensation can eliminate the negative impact of current agricultural production and guarantee the smooth environment-friendly agricultural production. Ecological values are largely influenced by the spatial and temporal dynamic variations and the accurate calculation of input costs and agricultural output remains a challenge. Competitive land utilization and the wide application of pesticides and chemical fertilizers can affect stable and efficient agricultural production, reduce the protein content of crops, and increase the probability of food pollution. Therefore, these magnitudes are so important argues for giving agro-ecosystem protection policy when considering the implications of an ecosystem service approach in future. [ABSTRACT FROM AUTHOR]

Utilization coefficient of irrigation water is a key indicator to measure agricultural water-saving efficiency, and it reflects comprehensively the level of water management and irrigation technology and so on. Obtaining reliable data of the utilization coefficient of irrigation water by direct in situ determination methods is difficult in large irrigation districts, but it can be determined by field experiments in the small-scale area. Hence, one of the challenges is to conduct researches on scale transformation in order to predict the utilization coefficient of irrigation water at large-scale irrigation district by the measured utilization coefficient of irrigation water at small irrigation district. The main characteristic of irrigation districts in riverine area is that there is no unified water diversion, and several small irrigation districts usually merge into a larger one. The area is a typical self-similar system. The existence and reusing of the agricultural returning water have induced much debates about the real water-saving potential of the irrigation districts in riverine area, and also the scale effect of utilization coefficient of irrigation water. The paper selected the rice irrigation districts of Yancheng City in Lixiahe riverine region as the experimental object. The study area is flat, where the river and ditch network are densely distributed. Totally, 4 large-scale irrigation districts, 11 medium-scale and 32 small-scale irrigation districts were selected to measure and calculate the utilization coefficient of irrigation water by inclusive method. The utilization coefficients of irrigation water in sampling irrigation districts with different scales were measured in 9 counties in 2012-2013. Fractal characteristics of these riverine irrigation districts were analyzed based on fractal theory. In addition, box dimensions of the Yancheng riverine area and the irrigation districts with different scales were respectively calculated by box-counting method. The box dimension ranged from 1.703 to 1.966, and increased with the increasing of irrigation district area scale. The scale transformation model of utilization coefficient of irrigation water was established based on the relationships among utilization coefficient of irrigation water, irrigation area and box dimension. The calibration results verified that the scale transformation model could predict the utilization coefficient of irrigation water in the riverine irrigation district with high prediction accuracy. With the developed model, the scale transformation of utilization coefficient of irrigation water was performed successfully. This study provides a new way to analyze the utilization coefficients of irrigation water and their transformation in different scales in riverine irrigation districts. In the future, if the means of geographic information system (GIS) is used in calculating the box dimensions, the accuracy of the research will be further improved. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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 Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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 Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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.)

Side channel pump is a kind of vane pump and has a small volume with low flow rate but high head. The specific speed of the pump is super low and usually it is used in the occasions that centrifugal pumps can't meet the requirements. In order to analyze the exchange mass flow in the gap between the impeller and the side channel, numerical calculation was applied to investigate flow characteristics in the gap under the operating condition with the highest efficiency in this paper. After simulating through commercial software CFX14.5, the head pulsation, exchange mass flow, pressure fluctuation and axial velocity in the gap were obtained in detail. At last, the hydraulic performance of the side channel pump was tested, and a comparison of hydraulic performance between simulation and test results was applied. Overall good agreement between the two results could be observed and the comparison verified the validity in simulating the flow characteristics of the impeller axial direction and radial gaps in the side channel pump. The simulation results showed that there was a fluctuation circle of the head when the impeller rotated by 18° and the head difference between maximum and minimum was about 0.07 m. The circulation flow between side channel and impeller changed in circumferential direction. One indicator for the form of the circulation flow was the exchange mass flow. The exchange mass flow under the maximum head operating condition was larger than that under the minimum head operating condition. Through the exchange mass flow's distributions in the right gap between the impeller and the side channel, it could be found that the fluid flowed from the impeller to the side channel in the outer radius of the right gap, and it flowed from the side channel to the impeller in the inner radius of the right gap. The transient pressure near the outer radius of the gap was larger than that in the inner radius, and the average maximum pressure was 2.8 times larger than the average minimum pressure during the whole rotating circle. It showed that the total pressure in the right gap increased sequentially along the direction of impeller rotation and in comparison, the pressure rose stronger in circumferential direction under the maximum head operating condition than under the minimum head operating condition. Because of circumferential flow, many vortexes were generated near the inlet of the impeller. The radial vortex affected the flow pattern of the side channel pump inevitably but the axial vortex was good for the energy transfer. Under the minimum head operating condition the streamlines were scattered more greatly than those under the maximum head operating condition, so it caused more flow loss during the pump's operation. As the flow exchange was the strongest in the outer radius of the right gap, the absolute value of velocity here was the largest, while the velocity in the left gap and inner radius kept an extreme small value. Net exchange flow decreased and increased alternatively like a trigonometric function image during the period of rotating circle, and the fluctuation of exchange flow led to the head pulsation of the side channel pump. The research results can provide a theoretical reference for improving the hydraulic performance of side channel pumps. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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 Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural 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.)