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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.)

The viability of probiotics can dominate the probiotic efficacy of products in the industrial production of probiotic preparations. Probiotics have been usually prepared in dry powder form for easy transportation and storage, in order to ensure a sufficient number of viable bacteria. Vacuum freeze drying can be often used for probiotic preparations in the industry at present. Nevertheless, the strain can be damaged inevitably during the vacuum freeze drying. The survival rate of the strain during the freeze drying can be improved to change the composition of the culture medium. One of the common growth factors, the uracil has often been added to the culture medium for the high proliferation of strains. Taking the uracil as the study material, this study aims to investigate the effect of adding trace growth factors to the medium on the freeze drying survival of the strain. The Lactiplantibacillus plantarum LIP-1was selected to isolate from Xinjiang sour mare milk with the probiotic effect. Firstly, the different concentrations of the uracil culture medium were configured to determine the optimal amount of uracil, where the freeze drying survival rate was taken as the index. Next, the optimal concentration group of uracil was set as the experimental group and the group without uracil as the control group. Finally, the cell damage of the strain was evaluated to clarify the influencing mechanism of uracil on the freeze drying survival rate of the Lactiplantibacillus plantarum LIP-1. The results showed that the addition of 0.05 g/L uracil to the culture medium significantly improved the number of viable bacteria and freeze drying survival rate of Lactiplantibacillus plantarum LIP-1 (P<0.05). The cell wall and cell membrane of Lactiplantibacillus plantarum LIP-1 after freeze drying were measured by Fourier infrared spectroscopy. In addition, the damage level to the cell wall and cell membrane of Lactiplantibacillus plantarum LIP-1 was evaluated after freeze drying by the lysozyme and NaCl sensitivity assay. The experimental results showed that the addition of 0.05 g/L uracil to the medium reduced the damage to the cell wall and cell membrane of the strain during the freeze drying. The whole genome sequencing of Lactiplantibacillus plantarum LIP-1 combined with real-time fluorescence quantitative PCR was selected to explore the internal mechanism. It was found that the addition of uracil increased the relative expression of UPRT and pyrH (P<0.05), which was the key gene for the uracil synthesis of UDP, and increased the relative expression of glmU (P<0.05), the key gene expressed by UDP GlcNAc, and the precursor of peptidoglycan synthesis (P<0.05), indicating the sufficient raw materials for the peptidoglycan synthesis. Thus, the content of peptidoglycan increased during the process. The increase of peptidoglycan content enhanced the stability of the cell wall. At the same time, the addition of uracil inhibited the relative expression of pyrE (P<0.05), a key gene for the conversion of orotic acid to uridine diphosphate, resulting in an increase in the intracellular content of orotic acid (P<0.05). It infers that the antioxidant capacity was reduced the degree of oxidation of unsaturated fatty acids in the cell membrane by reactive oxygen species, thereby reducing the degree of damage to the cell membrane of the strain. The strain reduced the freeze drying damage to the cell wall and cell membrane by metabolizing uracil, indicating the improved freeze drying survival rate of the strain. This finding can also provide a new idea for the high survival rate of the strain during vacuum freeze drying. [ABSTRACT FROM AUTHOR]

Lipase or lipase-producing lactic acid bacteria can be usually added to the cheese production process, in order to improve the sensory and flavor quality of cheese products. Taking the Xinjiang traditional cheese as the research object, this study aims to investigate the effects of lipase-producing lactic acid bacteria on the fatty acid and flavor of the cheese. Four strains of lipase-producing lactic acid bacteria (T1-5 and T1-3 are Weissella fusion, H1-6 is Lactobacillus helveticus, B2-5 is Lactobacillus plantarum) were selected in the previous stage of the experiment as a starter. Three strains were selected as the Lactic acid bacteria compounding for the yogurt cheese, according to the traditional technology. Experimental groups were: Group A T1-5 and T1-3, H1-6 (1:1:1), Group B H1-6, T1-5, B2-5 (1:1:1), Group C H1-6, T1-3, B2-5 (1:1:1), D group T1-3, T1-5, B2-5 (1:1:1); control group (group E): commercial starter. The physicochemical properties of the fermented and matured cheese were then characterized to clarify the effects of lipase-producing lactic acid bacteria on the cheese pH, titer acidity, and fat oxidation indicators. Gas chromatography (GC) was used to detect the fatty acid in the cheese, and gas chromatography-ion mobility spectrometry (GC-IMS) was used to identify the flavor substances in the cheese variety. The results showed that the pH and peroxide values of the cheeses in the four groups A, B, C, and D were significantly lower than those in the E group (control group) (P<0.05), whereas, the cheese titer values in the A and B groups were higher than those in the control E group. (P<0.05). There was no significant difference in the TBARS value between the five groups of cheese (P> 0.05). The contents of saturated fatty acid, monounsaturated fatty acid, and polyunsaturated fatty acid of the cheeses in groups A, B, C, and D were significantly higher than those in group E (P<0.05). The higher saturated fatty acids in the experimental group cheese were the meat Myristic acid (C14:0), palmitic acid (C16:0) and stearic acid (C18:0), as well as butyric acid (C4:0), caproic acid (C6:0), capric acid (C10:0) and Lauric acid (C12:0). The oleic acid (C18:1n9c) in the experimental group cheese was the main component of monounsaturated fatty acids. The linoleic acid (C18:2n6c) in the experimental group cheese was significantly higher than the control group (group E) (P<0.05). The GC-IMS and principal component analysis show that there were many types of volatile flavor compounds in group A and B cheese, indicating the high similarity. Aldehydes and esters were the main volatile flavor substances in the cheese, among which the 2-heptanone content of butyl aldehyde and butyl acetate was relatively high. There were relatively similar flavor substances in the two groups of cheeses C and E. The main volatile flavor substances in Group D were butyl acetate, 3-octanone, and heptanal, indicating a different fragrance from the others. Therefore, there were a better overall flavor and taste of A and B cheeses after the sensory evaluation, indicating the higher scores than the others. The screened lipase-producing lactic acid bacteria can be expected to serve as a starter to improve the quality of traditional Xinjiang cheese. [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.)

210Pbex and 137Cs measurements were carried out to trace the variations in soil depth and erosion rates in the cultivated and reforested land, aiming to explore the changes of soil retention due to the construction of the “Three North” shelterbelt program in the north of China. A typical shelterbelt and wind dominant region was selected, particularly on the Bashang Region of Zhangjiakou City, Hebei province, China. The results showed that in the cultivated land, both 137Cs and 210Pbex in the soil profile were uniformly distributed, due mainly to the mixing effect of tillage. In the reforested land, the 137Cs and 210Pbex concentrations in the 0-0.05 m soil layers were obviously higher than those in the other depth soil layers. There were roughly uniform concentrations of 137Cs and 210Pbex from 0.05 m to 0.15 m of the upper 0.15 m soil layer. It infers that the 137Cs and 210Pbex profile of soil can be changed after reforestation, thereby posing a great challenge on the use of 137Cs and 210Pbex to estimate the variation in soil erosion rates under the conditions of reforestation. A revised 210Pbex model of soil erosion in the reforested land was proposed using the 210Pbex mass balance equation in the temporal change trends of 137Cs and 210Pbex profiles. In the 137Cs proportional model, the mean soil erosion rates of reforested and cultivated land were 27.94±11.92 t/(hm² ·a) and 29.11±14.42 t/(hm² ·a). In the revised 210Pbex conversion model, the soil erosion rates of reforested and cultivated land were 82.16±14.36 t/(hm² ·a) and 68.55±22.11 t/(hm² ·a) before the construction of Three-North shelter forest, whereas, those were -41.28±33.91 t/(hm² ·a) and -8.52±47.32 t/(hm² ·a) after the constructed. It indicates that the 137Cs tracing can be used to characterize the average soil erosion rates and deposition rates on the slopes since 1963. Nevertheless, the 210Pbex tracer technology can be used to trace the variations in soil erosion rates before and after the shelter forest was constructed. In addition, the wind erosion rates of cultivated and reforested land obviously declined, due to the construction of Three-North Shelter Forest, where the cultivated and reforested land have been transformed from erosion zone to deposition zone in the study area. [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.)

Idle is one of the important operating conditions for non-road diesel engines. In China III, IV stage emission regulations from diesel engines for non-road mobile machinery, the proportion of idle condition in the eight-condition steady-state test cycle is 15% for the diesel engine operating at non-constant speed, and its ratio is 5% in the six-condition steady-state test cycle for the diesel engine with rated net power less than 19 kW and operating at unsteady speed. In China IV stage of non-road transient cycle (NRTC), the idle condition accounts for 4.52%. Due to the fact that the idle condition does not output power and also the fuel injection amount is small, the air-to-fuel ratio is relatively large and the combustion is incomplete at this time, which results in a large amount of fuel consumption and high emission of harmful gases. The land area with an altitude of more than 1 000 m in China is about 58% of the total area of the country, and proportion is about 33% for the plateau area with an altitude of more than 2 000 m. A large number of agricultural machinery powered by diesel engines operate at these areas. Compared with the sea level, atmospheric pressure will decline in plateau areas, the intake air mass flow rate decreases, and the operating performance at idle condition will further deteriorate. In order to investigate the effects of atmospheric pressure on combustion characteristics and emission performance of a small agricultural diesel engine at idle condition, the change law of combustion and emission performance of the small agricultural diesel engine, which meets the emission standard of China III non-road mobile machinery, was studied at different atmospheric pressures such as 80, 90, 100 kPa by using atmospheric pressure simulator. The experimental results demonstrated that the turbocharger matched with the small agricultural diesel engine did not work, and also the turbocharger system did not have self-compensation capability in plateau area at idle condition. Peak in-cylinder pressure, peak in-cylinder pressure rise rate, and peak heat release rate all go up with an increasing of atmospheric pressure; the average increase rate were 13.33%, 37.24% and 6.76%, respectively, with atmospheric pressure increased per 10 kPa. However, peak in-cylinder combustion temperature showed a decreased tendency with atmospheric pressure increased; the average decrease rate was 11.18% with atmospheric pressure increased per 10 kPa. Atmospheric pressure had a great influence on carbon monoxide (CO) emission and hydrocarbon (HC) emission. CO emission and HC emission declined sharply with an increasing of atmospheric pressure; the average decrease rate were 47.47% and 55.77%, respectively, with atmospheric pressure increased per 10 kPa. The variation range of nitrogen oxides (NOx) emission and smoke were relatively small with atmospheric pressure increased. With atmospheric pressure increased per 10 kPa, the average NOx emission increased 18.93%, while the average smoke reduced 11.90%. This research can provide a reference for the establishment of emission control strategy for a small agricultural diesel engine at idle condition in a plateau area. [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.)

The environment pressure and air density experience sharp declines at high altitude, which cause a large drop in the intake air mass flow rate of diesel engines. As a result, many aspects of engine performance are deteriorated, such as power, fuel consumption and emissions. Turbocharging matching provides a good technical solution for recovery diesel engine performance at high altitude. There is a large number of agricultural machinery operating in plateau area of China. In order to ensure that the agricultural machinery used in these areas had a good plateau adaptability, taking a small agricultural diesel engine as the research object, an appropriate compressor and turbine were selected respectively through theoretical calculation according to the design and development goals at altitude of 2 000 m. After that, the matching test of the small agricultural diesel engine and selected turbocharger was conducted at this altitude. Finally, the simulation model of the small agricultural turbocharged diesel engine was built by using GT-Power code based on test data. The change rule of diesel engine key performance parameters were simulated and investigated at altitudes of 0, 2 000 and 4 000 m. The results showed that the selected turbocharger made the small agricultural diesel engine achieve the development requirements at the altitude of 2 000 m. Low-end torque reached 120.1 N·m at 1 000 r/min, the peak torque was 180.2 N·m at 1 600 r/min, the rated power was 37.4 kW at 2 600 r/min, and the torque backup coefficient was 131% at this altitude. At 3 altitudes of 0, 2 000 and 4 000 m, the joint operation lines of the small agricultural diesel engine and the selected compressor were all operating in the relatively high efficiency area, and there were a large surge margin at low engine speeds, and also a certain distance from the choke line at high engine speeds. As the altitude went up, the engine torque and boost pressure decreased, while brake specific fuel consumption and turbine inlet gas temperature increased. What’s more, with respect to high engine speed, the change of altitude had a greater impact on engine power and economy performance at low engine speed. With the increase of altitude, decreasing amplitude of torque and percentage gain of fuel consumption was both rose at low engine speed, and these tendency were decline gradually with the increase of engine speed. In addition, the engine speed corresponding to the peak torque showed a tendency of gradually moving towards higher engine speed at high altitude. Compared with plain area, the maximum engine torque decreased by 2.59% and 7.19% respectively when it ran at altitudes of 2 000 and 4 000 m. Meanwhile, compared with the previous literatures conclusion, the decreasing amplitude of peak engine torque was smaller when the small agricultural diesel engine operating at altitudes of 2 000 and 4 000 m, respectively. It can ensure the good operation performance of diesel engine in plateau area, and also is beneficial to improve the plateau adaptability when diesel engine and turbocharger are matched at high altitude. [ABSTRACT FROM AUTHOR]

Winter bamboo shoots are not only of great value but also in great demand, but it is difficult to find in the field. There is no specialized detecting device in the market except expensive ground penetrating radar and the EM-38 earth electromagnetic induction instrument. However, their prices are more than 100,000 RMB. Therefore, in this study, we not merely built a winter-bamboo-shoots-soil permittivity model at high frequencies, but also analyzed traditional time-domain reflectometry (TDR). As such we finally put forward a method of detecting winter bamboo shoots based on time-domain reflection. Then, according to the detecting method, a new winter bamboo boots detector with low cost and convenient operation was designed. Electromagnetic waves have different propagation velocities and attenuation rates in different medium, accordingly the amplitude ratio and the phase difference of microwaves show differences through different medium. Hence, the detector first emitted and received microwaves by two antennas. Then the differences of amplitude ratio and phase difference appeared so that the detector can distinguish whether there were winter bamboo shoots or not. The whole detector was divided into three modules: high frequency module, low frequency module and antenna module. Hardware of the detector included following modules: A high frequency signal source system based on phase locked loop (PLL), wave filters, an amplitude and phase detection system, antennas, microprocessors and related Analog to Digital Converter (ADC), buzzers and buttons, etc. Software system was set up founded on the hardware. The high frequency signal source was mainly based on ADF4350, the amplitude and phase detection module was based on AD8302, and the microprocessor was STC15L2K. The detector used two antennas of the same type to receive and transmit microwaves. The 3×3 Latin square experiment was used to optimize the parameters. In the test, the moisture content of the soil was measured by soil moisture sensor first. Then the processor set thresholds of the amplitude ratio and the phase difference according to the soil moisture content so that the buzzer sounded the alarm automatically as soon as the collected value exceeded the threshold. In addition, winter bamboo shoots were buried in the soil as a control group, and the soil was detected by microwaves of different frequencies. The test showed that stones and bamboo leaves hardly had an impact on the detector. It also showed that the result was most obvious when the microwave frequency was 790 MHz. In this case, the analog voltage generated by the amplitude ratio of the soil with winter bamboo shoots was less than that of the solid without winter bamboo shoots by at least 15%, and the analog voltage generated by the phase difference was at least 15% higher than that of the solid without winter bamboo shoots. Many field detective tests were done in bamboo forest which showed that the winter bamboo shoots detector had an accuracy rate of approximately 70%. In conclusion, the winter bamboo shoots detector had both stable performance and high accuracy, which can save more than 25% of the searching time, and its cost was less than 1/10 of that of ground penetrating radar. [ABSTRACT FROM AUTHOR]

Changes in behavioral activity are increasingly recognized as a useful indicator of dairy cows’ health and welfare. The classifying of changes in behavioral activity can be useful in early detection and prevention of diseases, and monitoring dairy cows’ behavioral activity helps farmers to take a comprehensive view of the dairy cows’ estrus time. The aim of this study is to automatically measure and distinguish several behavior activities of dairy cows from accelerometer data. The study consists of 2 parts, namely, wireless leg sensor and binary decision-tree algorithm. The wireless leg sensor was designed to collect test data, which integrates microcontroller MSP430F149IMP, tri-axial accelerometer ADXL345, and radio frequency module CC1101 to meet the requirements of accurately collecting data of the acceleration of dairy cows, and long-term reliable transmission of data. The binary decision-tree algorithm was designed to classify the behavior of dairy cows. Firstly, 24 statistical features describing the magnitude, symmetry, steepness, variability, uncertainty and angle of the three-axis acceleration of cow legs were selected. Secondly, the best classification behavior category and optimal threshold of each statistical feature were obtained by constructing ROC(receiver operating characteristic) curve. Then the information gain is used as the selection criterion for the split attribute of the binary decision-tree model. Finally, a optimal binary decision tree classification model is constructed to classify and recognize the dairy cow motion behavior. Compared with the traditional binary decision-tree algorithm, the innovation of the algorithm is as follows: Firstly, the ROC curve principle is used to ensure the classification and threshold of each statistical feature to select the local optimal. Then the information gain is used as the split attribute selection standard, and the binary decision-tree classification model is constructed to realize the overall optimal classification of the behavior characteristics of the dairy cows. The results illustrate that the optimal binary decision-tree algorithm can accurately classify 6 types of biologically relevant behavior: standing (88.59% sensitivity, 83.35% precision, and 85.89% F1 score ), lying (85.59% sensitivity, 86.04% precision, and 86% F1 score), normal walking (73.91% sensitivity, 84.25% precision, and 78.74% F1 score), active walking (75.75% sensitivity, 74.46% precision, and 75.1% F1 score), standing up (67.63% sensitivity, 67.81% precision, and 67.72% F1 score), and lying down (66.96% sensitivity, 65.06% precision, and 65.99% F1 score). The highest sensitivity was 88.59% for standing and the sensitivity was good for all classes of behavior except standing up and lying down. The best precision was achieved for standing, lying, and normal walking. The precision for active walking classification was slightly lower but substantially better than those for standing up and lying down. Standing and lying behavior were classified correctly to a high degree, but were also misclassified as other behavior. Normal walking was mainly misclassified as either standing or active walking (18.79% of the cases). Active walking was misclassified most often as standing or normal walking (18.43% of the cases). Standing up and lying down were mostly confused with each other (15.53% and 14.92% of the cases, respectively). The average sensitivity, the average precision and the average F1 score of the classification are 76.47%, 76.83%, and 76.57% respectively. Compared with the traditional ID3 (iterative dichotomiser 3) decision-tree algorithm, they are increased by 5.71 percentage points, 5.4 percentage points and 5.61 percentage points respectively; they are increased by 7.51 percentage points, 8.02 percentage points and 7.77 percentage points respectively compared with the K-means clustering algorithm, and 6.77 percentage points, 6.72 percentage points and 6. 57 percentage points respectively compared with the support vector machine algorithm. The experimental results show that the optimal binary decision-tree algorithm has the characteristics of simple classification rules and high classification accuracy. This research of the method can provide an effective theoretical support for improving the classification accuracy of dairy cow behavior. [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.)

Overland flow is the initial motivation of slope surface erosion and the key reason for soil degradation. In order to study the influence of rainfall intensity and roughness on slope surface water dynamic characteristic, the artificial simulated rainfall experiments were carried in the Soil and Water Conservation Engineering Laboratory in Northwest A&F University. Based on the basic theory of fluid mechanics and hydraulics, the influence of rainfall intensity and roughness on hydrodynamic characteristics of overland flow was meticulously investigated. The experiment included 6 roughness, 5 flow discharges and 5 rainfall intensity. The theory of friction velocity and viscous sublayer in sediment movement mechanics were also applied in this study. Results showed that under the stage of overland flow, the data points of flow resistance coefficient was far from the laminar flow line and turbulent flow line with the continuous increase of roughness when the roughness was smaller than or equaled to 1.77, indicating that the bed surface roughness of slope surface had an effect of resistance increase to flow resistance. However, the resistance coefficient fluctuated to being relative stable when the roughness was greater than 1.77 mm. Under the rainfall condition, the resistance coefficient decreased with the increase of rainfall intensity when roughness was closer to 0. In addition, the resistance coefficient was concentrated when the roughness increased. Under the stage of different rainfall intensity and roughness, the overland flow was accompanied by production and disappearance of roll wave. The phenomenon could be expressed by the ratio of viscous sublayer thickness and mean water depth. By observation, the ratio at roughness of 3.68 when the roll wave was obvious was calculated. When the ratio was between 0.382 4 and 0.599 3 (the difference was 0.24), the overland flow was in transition zone, otherwise, in roll wave zones. On the conditions of same roughness and rainfall intensity, Darcy-Weisbach resistance coefficient would decrease with the increase of turbulent flow Reynolds number. Under the condition of the same roughness, the resistance coefficient decreased with the increase of rainfall intensity. The resistance coefficient was 1.25-2.6, 1.3-2.7, 1.8-3.0, 1.8-3.15, 1.8-3.15, showing a trend of increase than being stable with increase of resistance coefficient. The turbulent flow Reynolds number was 0.35-36.1, belonging to transitional flow zone (0.35-900) according to turbulent flow Reynolds number standard but belonging to transitional and laminar flow zone according to traditional Reynolds number standard. It indicated that the standard for overland flow deserved further study. Based on the critical water depth, the overland flow was in rapid zone mostly. As the roughness increased, the flow transferred from rapid zone to slack zone. In addition, this study provided an overland flow resistance calculation formula by comprehensively considering viscous resistance, circle resistance and rainfall resistance. By validation, the formula had a high accuracy with R2 of 0.92 (P<0.05). The results are helpful to understand hydraulic flow erosion mechanism of slope surface, and provide data support for building soil erosion model. [ABSTRACT FROM AUTHOR]

China Stage III emission standard for diesel engine of non-road mobile machinery has been executed since April 1, 2016. Some manufactures have begun to adopt a high pressure common rail system to cope with this emission regulation. Fuel injection parameters can be adjusted flexibly by using the high pressure common rail system. Therefore, combustion process can be improved. However, it brings the problem of increasing the workload of the calibration and optimization significantly. With the increasing of calibration variables, the calibration combinations will increase exponentially. The traditional calibration method, such as the single variable search method or the single variable sweep method, their calibration results may not be able to make the engine to achieve best performance, especially when the number of calibration parameters is more than two. Nowadays, a majority of optimization calibration methods are using a non-parametric modeling method to fit the calibration model and optimizing the calibration model by using an intelligent optimization algorithm. However, the non-parametric modeling method cannot give the descriptions of the model structure or the model coefficients. Meanwhile, it needs a large number of test data to fit an accurate calibration model. Moreover, the non-parametric modeling method and the intelligent optimization algorithm are both very complex. A polynomial modeling method has a good compromise between complexity and computational efficiency of the model. Therefore, in allusion to the calibration stage of a non-road high pressure common rail diesel engine, 4 calibration variables, i.e., main injection quantity, pilot injection quantity, main injection timing and injection pressure, were chosen as the factors. The non-road diesel engine design index and related constraint parameters were chosen as the responses at the peak torque speed of 1 600 r/min and the rated power speed of 2 600 r/min, respectively. The reasonable factor levels of the design of experiments (DoE) were selected. By using the response surface methodology (RSM) of Box-Behnken design, the DoE matrices were obtained at the engine speed of 1 600 r/min and 2 600 r/min, respectively. Meanwhile, the corresponding test was conducted according to the experiment design. The second order regression models of all the responses were got and evaluated. The interaction effects of the 4 calibration parameters on engine performance were investigated by using the RSM. The corresponding optimization was conducted respectively at the engine speed of 1 600 and 2 600 r/min taking the target torque and target power as the setting target under the principle of the minimum brake specific fuel consumption, the maximum air-to-fuel ratio, the minimum peak cylinder pressure and gas temperature of exhaust manifold. The combination of calibration variables was obtained at 2 engine speeds, and the proposed method was verified by experiments. The results showed that all the quadratic response surface regression models had a good accuracy and a good predictive ability. The determination coefficient R2, the adjusted determination coefficient R2adj, and the prediction determination coefficient R2pred were all above 0.92. The maximum error between test value and predicted value was less than 3.07 %. With the optimized calibration parameters, the peak torque and the rated power of the non-road high pressure common rail diesel engine reached 200.7 N.m and 40.1 kW, respectively. The engine achieved the design index, and moreover, the brake specific fuel consumption, air-to-fuel ratio, peak cylinder pressure, and gas temperature of exhaust manifold were all under the range of acceptance. It is feasible to optimize the diesel engine design point by using the RSM. [ABSTRACT FROM AUTHOR]

As one of the most popular nuts produced in China, pecan contains large amounts of protein and a variety of unsaturated fatty acids required for human body. However, pecans are prone to rancidity because of the influence of environmental factors such as light, oxygen, and moisture. Therefore, the detection of pecan's quality has a certain practical significance. As a bionic electronic system, electronic nose (E-nose) detects the quality of pecan qualitatively and quantitatively through the analysis of sample volatile gas's fingerprint information, and is pretty suitable for pecan quality detection. However, pecan odor is comprised of complicated compositions and small differences exist among pecans with different qualities, which makes the detection difficult. In order to improve the accuracy of detection, it's essential to optimize the sensor array of E-nose during the application. In this research, an embedded E-nose based on digital signal processer (DSP) was designed for pecan detection, and 4 batches of pecans with different aging time were used for experiment. According to the existing GC-MS (gas chromatography - mass spectrometer) analysis of pecan volatile, 13 gas sensors were selected, and part of them with small response were obsoleted by analyzing the response curve of each sensor firstly. Then, 3 feature extraction methods were applied to each sensor's abstraction to generate the initial feature matrix, thus the mean differential coefficient value, stable value and response area value. After that, a series of data analysis methods were applied to select the features with good performance and realize the optimization of array. First, features with smaller otherness were rejected by the mean analysis. Then, variation coefficient was used to remove the features with poor stability. Afterwards, the features reserved were classified through the cluster analysis based on the correlation, and the feature with the minimum redundancy in each class was selected according to the result of correlation coefficient analysis. Eventually, the degree of matrix's multicollinearity was decreased by removing the features with high value of variance inflation factor, and the optimized sensor array was chosen according to the ultimate feature matrix. To verify the validity of optimization, principal component analysis (PCA) and partial least squares regression (PLSR) were used to compare the ability of discrimination and forecast between the data before and after optimization. Results indicated that pecans different in aging time were well classified by using the optimized array. Each group of samples were clustered closely in PCA score plot, and the contribution rates of the first 2 principal components of the optimized array (they were 76.01% and 14.60%, respectively) were obviously better than that of pre-optimized array (they were 66.36% and 13.45%, respectively). Meanwhile, the result of PLSR showed that the fitting determination coefficients and root mean square error (RMSE) of the regression model based on the optimized array (R2=0.933 4, RMSE=1.452 9 d) performed better than that based on the pre-optimized array (R2=0.888 7, RMSE=2.509 2 d), and there was little difference of prediction parameters between the training set and validation set, which meant the phenomena of over-fit didn't exist and the ability of forecast was better for the optimized array. As a result, through the optimization of sensor array, E-nose can perform better in the detection of pecan's quality and reduce the dimension of data, and the research provides an efficient method for E-nose’s application in various fields. [ABSTRACT FROM AUTHOR]

Closed cultivation is a new type of cultivation model, which is widely used in solar greenhouse, and it uses EC as the performance index of the regulation process of nutrient solution. In the study, a dynamic analysis was conducted on the regulation process of closed culture nutrient solution with two-step mixed fertilizer characteristics. PID control algorithm was used to control the regulation process of the nutrient solution, and the effects of 6 factors on control process were analyzed through comparative experiment. The results showed that it was difficult to use a precise model to characterize the fertilizer mixing process, since the output liquid flow rate, the fertilizer concentration and the PID parameters had great influence on the control effect of the two-step mixed fertilizer system. Experiments were carried out to find the effect of different output liquid flow rates, fertilizer concentration and the PID parameters, on PID control model. The results were obtained using the fixed variable method and orthogonal tests, under the target electrical conductivity (EC) of 2.3. The experimental results showed that the time of the system decreased with the decrease of the output liquid flow rate or the increase of the fertilizer concentration. Duration of system oscillation and overshoot amount increased with the decrease of the output liquid flow rate or the increase of the fertilizer concentration. Keeping the fertilizer concentration and the PID parameters (obtained under the condition that the output liquid flow rate was 4 m3/h and the fertilizer concentration was 4 channels) unchanged, and the target EC of 2.3, the duration of system oscillation was changed from 15 s to 125 s while the output liquid flow rate was changed from 10 m3/h to 4 m3/h, and, the stable time was changed from 180 s to 205 s and the overshoot was changed from 1% to 20%. Keeping the output liquid flow rate and the PID parameters (obtained under the condition that the output liquid flow rate was 4 m3/h and the fertilizer concentration was 4 channels) unchanged and the target EC of 2.3, the duration of system oscillation was changed from 40 s to 125 s while the number of the fertilizer opening channel was changed from 1 channel to 4 channels, the stable time was changed from 255 s to 205 s, and the overshoot was changed from 3% to 20%. According to the different executive agencies and environmental factors, it was necessary to adjust the PID parameter of the system to achieve better control effect. The closed cultivation system ran with high efficiency and stability using the adjusted PID parameters. According to the test results and analysis, the optimal output liquid flow rate and the concentration of the fertilizer solution in closed culture system with two-step mixed fertilizer were 6 m3/h and 200 g/L, respectively. Under this condition, the PID control parameters were adjusted, and the stability time of the system was 100 s, the overshoot was 3%, and the duration of oscillation was 25 s. In summary, the nutrient solution of the closed type cultivation system with double mixed fertilizer could be regulated by the PID algorithm to achieve stable and efficient operation, which provided a reference for the regulation. [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.)

In practical engineering, buried pipe is the form of well group. At present, there are two ways to calculate the heat transfer in a group of wells. One is to calculate the heat transfer of a single well, which is then directly multiplied by the number of holes to get the heat transfer of well group, without consideration of the thermal interference between wells. The other is the direct use of analytical solution or numerical simulation. The numerical solution of the powerful is good at calculating complex heat transfer problems, and can effectively grasp the dynamic heat transfer characteristics of buried pipe. The heat transfer space is large and the geometry configuration is complex, so the computation time is too long. In order to establish a heat transfer model of well group that can be quickly solved and used for thermal disturbance characteristics, the mixed solution heat transfer model based on analytical and numerical calculation is presented. The basic idea is to divide the space of the well group into the space inside borehole(including multiple drilling holes) and outside borehole taking the borehole wall as the boundary. Both steady-state analytical method and transient numerical heat transfer method are used to analyze the heat transfer characteristics inside and outside borehole respectively, and the 2 regions are coupled by the borehole wall temperature. After the establishment of summer conditions of single drill pipe heat exchanger test-bed, and the verification of single well heat transfer model, the FLUENT software in combination with the heat transfer model of well group is used to further study the wells at 3 kinds of special positions in the square well group(middle well, edge well and corner well), and the typical well group of physical model is determined and the thermal interference coefficient of the well group is defined. Finally, the thermal interference characteristics of the typical well group are studied mainly under the condition of continuous operation in summer. The research results show that with the development of heat exchanger of well group, the heat interference between wells in well group is generated and gradually increases, and at the same time the degree of heat interference for the middle of well is the largest, followed by the edge of well and the corner of well; due to the influence of heat interference, the heat transfer capability of the corner of well is the biggest and its borehole wall temperature is the lowest, the heat exchange ability and borehole wall temperature of the edge of well are in the middle, and the heat transfer capability of the middle of well is the minimum and its borehole wall temperature is the highest. After running for 90 d, the heat exchange of the corner of well is 6.5% more than the edge of well, and the heat exchange of the edge of well is 7.1% more than the middle of well; the contribution rate of heat exchange of the corner of well to the well group is gradually increased with the running time, that of the middle of well is gradually reduced with the running time, while that of the edge of well is basically unchanged. [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.)

As the most important procedures during sugarcane harvesting, leaves cleaning and tails severing are influenced by different growth height and lodging status, and the operating speeds of the rollers not only affect the operating efficiency of the sugarcane harvester, but also influence the quality of harvesting. In order to investigate the effect laws on the quality of peeling leaves and breaking tails of leaf-crushing impeller, leaf-cleaning impeller and tail wheel, the leaf-crushing and tail-breaking system was designed and manufactured for sugarcane harvester test bench after sugarcane harvesting. In the system, elastic wire springs were arranged uniformly on the leaf-crushing impellers, the outer edge of the leaf-cleaning impeller were installed with rubber plates, and the severing tail components on the tail wheels were elastic rib. As the test bench works, the rolling leaf-crushing impeller, leaf-cleaning impeller and tail wheel lacerated and peeled leaves attached tightly on the canes by producing centrifugal and frictional force. According to the mechanical properties that anti-deformation and impact resistance of the tails were significantly lower than other parts, the anti-float mechanism was designed for breaking tails, the groove of the circular arc can prevent the lateral movement and ensure the smooth transportation of the sugarcane. The experiments of peeling leaves and breaking tails of sugarcanes were conducted in Zhejiang University, 2015. A quadratic general rotary unitized design was carried out with leaf-crushing impeller speed, leaf-cleaning speed and tail wheel speed as experimental factors, and with non-cleaning rate, tail broken rate, skin broken rate and non-break rate as experiment indices. By using SAS 9.3 regression analysis method, response surface method and combined with nonlinear optimization calculation method, the working parameters were calculated optimally, and the optimal factor combination was established. The results indicated that, the tail-broken rate and skin broken rate were influenced by the speeds of the three impellers significantly, however, the non-break rate was influenced by the speed of tail wheel only, but it had no effect on the non-cleaning rate. The contribution rate order of non-cleaning rate was leaf-crushing impeller speed, leaf-cleaning speed and tail wheel speed. The contribution rate order of tail broken rate was tail wheel speed, leaf-crushing impeller speed and leaf-cleaning speed. The contribution rate order of skin broken rate was tail wheel speed, leaf-cleaning speed and leaf-crushing impeller speed. The contribution rate order of non-break rate was tail wheel speed, leaf-cleaning speed and leaf-crushing impeller speed. The optimum parameter combination of the test bench after optimization was 512.9 r/min of leaf-crushing impeller speed, 418.8 r/min of leaf-cleaning speed and 307.0 r/min of tail wheel speed. At this level, non-cleaning rate achieved theoretical optimum value of 4.98%, tail broken rate was 88.39%, skin broken rate was 5.19% and non-break rate was 96.21%.Verification experiment showed that the experimental value of non-cleaning rate was 4.86%, tail broken rate was 90%, skin broken rate was 4.78% and non-break rate was 97.5%, which indicated that the experimental values were consistent with predicted results, and regression models established by the experiment were appropriate, which can provide references to design whole-stalk sugarcane harvester and improve the harvesting quality. [ABSTRACT FROM AUTHOR]