Transactions of the Chinese Society of Agricultural Engineering, the 1st in Agricultural Engineering, is supervised by China Association for Science and Technology, and sponsored by Chinese Society of Agricultural Engineering. It aims to introduce the latest scientific achievements and developing trends of Agricultural Engineering and provides the academic developments abroad and domestic of the discipline. The scope covers agricultural water-soil engineering, agricultural information and electrical technology, agricultural products processing engineering.
The journal is included in EI, JST, Pж(AJ), CA and CSCD.
Editor-in-Chief Zhu Ming
Deputy Editor-in-Chief Wei Xiuju Zhang Ruihong Xi Weimin Wang Liu Wang Yingkuan Li Pingping Ying Yibin Tong Jin Yun Wenju Zhao Chunjiang Kang Shaozhong
The pulse width modulation (PWM) technology is an important means to achieve variable-rate spray and is attracting more and more researchers’ attention due to its short reaction time, fast response, large flow adjustment range, and good spray characteristics using conventional nozzles, but during the actual spraying process, its working parameters and environmental conditions could influence the spray accuracy seriously. In order to investigate the atomization and deposition characteristics of the PWM variable-rate nozzle, we designed a pulse width modulation variable-rate spraying system to study the spraying atomization and deposition characteristics of TR80-005 C hollow cone spray nozzle commonly used in agricultural application. The experiments were carried out in the type IEA-II wind tunnel designed by the Agricultural Intelligent Equipment Technology Research Center to maintain a stable environmental condition to produce setting wind speed. A capacitive droplet deposition sensor of dot matrix placement was used to detect spray deposition in real time. To effectively evaluate the ground deposition properties of the wind tunnel environment, the deposition evaluation index (DEIX) was deduced based on drift potional index (DIX). The DEIX is inversely proportional to DIX: the lower the DEIX is, the lower the droplet deposition potential will be, which means that the possibility of drift loss is greater. The Spraytec (droplet size meter) was sued to test the droplet volume median diameter (VMD) and the relative span (RS) of the droplets to determine the relationship between duty cycle and spraying atomization performance. The experiment was carried out at the Xiaotangshan National Experiment Station for Precision Agriculture in Changping District of Beijing. The test devices were mainly composed of a PWM variable-rate spraying system, a IEA-II conventional speed wind tunnel, a laser particle size analyzer, and a deposition measurement sensor network system. Before tests, all systems were powered on and warmed up for 30 minutes. In the droplet size tests, the nozzle was placed 0.5 m directly above the droplet size analyzer; the test pressure was set as 0.4 MPa; the PWM frequency was as 1 Hz; the duty cycle was as 10%–60% at the interval of 10%. Tap water was used as the spraying solution, and each setting repeated five times. For the droplet deposition characteristic tests, the droplet deposition sensor was arranged at the bottom of the wind tunnel. The sensors were arranged in five rows (1 m spacing) and three columns (0.55 m spacing) in the vertical wind direction, and were numbered 1 to 15 starting from the upper side to the bottom of the upper side. The nozzle was fixed at the top of the wind tunnel, and the height of the relative deposition sensor was set as 1 and 1.5 m, respectively. The horizontal distance between the nozzle and the first column deposition sensor was 1.3 m; the wind speed was set as 1–5 m/s; the PWM frequency as 1 Hz; the duty cycle as 10%–60%; the spraying time as 10 s; the spraying pressure as 0.4 MPa. At the beginning of the test, the sensors saved data in real time and transmitted it back to the computer. The test results showed that when the duty cycle was between 10% and 40%, the VMD decreased with the increases in duty cycle, the VMD was 122.3 μm in the 60% duty cycle, which increased by 1.8 μm compared with that in the 40% duty cycle. When the PWM duty cycle was 60%, the RS was the lowest compared with that in the 20% duty cycle; the RS decreased by 9.52%, which means that the droplet spectrum was the narrowest, and the droplet size distribution was the most concentrated. In the deposition test, at the wind speed at 1 m/s, droplets mainly deposited within 3.3 m from the nozzle, which accounted for 95.7% of the total deposition. When the wind speed exceeded 3 m/s, the droplet deposition distance increased under airflow, which may increase the possibility of spray drift. With the increase in the duty cycle, the DEIX fell and the drift rate of the droplets rose. Under the same working conditions, the greater the wind speed and the nozzle height were, the lower the DEIX and the easier the spray drift would be. This study provides a basis for the practical application of PWM variable-rate spraying technology and the selection of PWM working condition parameters in agricultural field production, and lays the theoretical groundwork for further optimization of the PWM variable regulator.
The traditional land consolidation with high-intensity engineering construction, guided by unified engineering construction and rigid engineering construction standards, with the goal of regularization and hardening, has played an active role in stabilizing the amount of cultivated land and improving agricultural production conditions. However, it is unsustainable in current ecological civilization construction. The high-intensity mechanical operation severely disturbed the ecological environment in the study area in a short time. The lack of ecological consideration destroyed the overall ecological pattern and ecological stability of the study area. As the region suffering from the most serious conflict between modernization and traditional agriculture, Jiangnan water town has more complex land use structure and fragile ecological landscape. There is an urgent need for ecological improvement and landscape improvement through ecological land consolidation. Guided by the theory of landscape ecology, this study selects a typical project following the idea of “landscape pattern evaluation—function division of land consolidation—corridor pattern optimization—polygon matrix optimization” based on ecological landscape evaluation and the minimum resistance model. Then we estimate the investment of the proposal to judge its feasibility according to relevant planning and design standards. Finally, we verified the land consolidation proposal from the aspects of engineering construction and ecological security of landscapes. The implementation of the plan resulted a great improvement, including an increase by 40.79% in the coverage of the ditches, an increase of 60.06% in the coverage of road functions, 1.24 hm
2 of newly constructed artificial wetlands, an increase of 447.31% in the density of ditch corridors. The circuity of the ditches was enhanced by 114.91%; the connectivity and circuity of the water corridors were increased by 55.43% and 454.95%, respectively, and the ecological security index of landscapes of the study area was raised by 35.56%. These results show that the ecological land consolidation proposal is worthy of extension on the basis of traditional land consolidation in terms of objectives, models, and methods. The ecological land consolidation should integrate the multi-field methods such as landscape pattern analysis, minimum resistance model, and the prevention technology of non-point source pollution with traditional land consolidation planning methods such as land consolidation division and the road–ditch layout to promote the multi-purpose goal of land consolidation. For the Jiangnan water town area, it should take into account the agricultural production targets, the current pressure of urbanization and industrialization, and the improvement potential of rural landscapes enriched with cultural characteristics. The proposal should point out the direction of rational consolidation according to local conditions, and combine traditional engineering consolidation methods with regional industrial characteristics. Through the ecological land consolidation proposal of this study, the overall ecological security of landscapes of the study area can be improved when we achieve the goal of improving agricultural facilities. This research can provide a reference for enriching the land consolidation planning method and exploring the ecological transformation path of land consolidation.
In the development of precision agriculture, intelligent agricultural machinery is an effective way to alleviate the current tense situation in world food security. The complex field environment and meticulous work effects require the agricultural machinery to have the ability of perceiving the attitude of the agricultural machinery accurately in real time. For example, the precision navigation control and the leveling control of agricultural machinery are all dependent on the accurate attitude measurement. What is more, the attitude of agricultural machinery is one of the key parameters of agricultural mechanics modeling and agricultural machinery safety warning learning. However, the external acceleration of the vehicle, which is commonplace under dynamic operation conditions, poses a challenge. The paper developed a minimal hardware system for external acceleration identification and attitude estimation used for field working vehicles and verified by the experiments taken place on the Innova 2100 shaker and the ZP9500 sprayer of high ground clearance in the field in order to further improve the precision operation of agricultural machinery. The modern micro-electromechanical systems (MEMS) technology provides the moderate-cost and miniaturized solutions for the development of attitude reference system. With the highly integrated inertial measurement units (IMUs) ADIS16445 provided by ADI company and micro ARM processor STM32 F446 provided by ST Company, the hardware platform was built. ADIS16445 ISensor® included tri-axial gyroscopes and tri-axial accelerometers. The raw sensors data were sampled by STM32 F446 RC processor through SPI interface. The attitude calculation was carried out based on the direction cosine matrix algorithm. Based on the gyroscope and accelerometer measurement model, a first-order external acceleration measurement model was proposed, and a Kalman filtering fusion algorithm with four state vectors was established. Since the bias of gyroscopes and accelerometers was stable after hardware pre-heating, the impact of bias of MEMS inertial sensors in the fusion algorithm was not considered. Innova 2100 shaker is standard equipment of rotary motion, and different centripetal accelerations can be achieved to verify the external acceleration identification at varying rotation speeds. Innova 2100 shaker test results show that the measurement error is less than 0.214 m/s
2 under the external acceleration lower than 10
g. Field experiments were conducted on Innova 2100 shaker and the ZP9500 sprayer of high ground clearance provided by LOVOL Company with the assistance of attitude and heading reference system (AHRS) MTi300 provided by Xsens Company. The MTi300 AHRS provides high precision attitude and heading output with high stability and fast dynamic response with dynamic measurement accuracy of 0.3°, which makes it widely used in navigation implements, automobiles, agricultural machinery, and other fields. The experiment results from the sprayer of high ground clearance show that compared to the MTi300 AHRS, the average and maximum measurement errors of the roll angle are 0.069° and 0.23°, respectively. The average and maximum measurement errors of pitch angle are 0.078° and 0.39°, respectively. The test results verify that the proposed Kalman filtering algorithm is accurate and stable, which can improve the quality of agricultural machinery operations and have more applicability.
Flooding is one of main disasters for agricultural production in China. Its influence on rice is rarely studied in Guizhong District in Guangxi. In this study, we investigated the effects of different flooding durations at different growth stages on the growth and yield components of rice. The experiment was carried out in Nalu Village of Laibing City, Guangxi, China (109°52’ E, 24°4’N). The soil was sandy loam. As early and late rice, Sixiang 1 and Baixiang 139 were planted in pots in 2015 and 2016, respectively. Flooding of early rice started at different growth stages of tillering, booting and flowering. At each growth stage, flooding lasted for 0 (control), 2, 4, 6, 8, and 10 days, respectively. Because the precipitation during the booting and flowering stages of late rice was small, the flooding of late rice was carried out on three different days at tillering stage. At flooding, the water surface remained 2–3 cm higher than the plant height. The flooding duration of late rice was same as that of early rice. During the experiment, the tiller numbers before and after flooding, the heading stage time and its duration, grain number per panicle, seed-setting rate, 1 000-grain weight and yield per pot after harvest were determined, and the relationships between yield and yield components were subjected to path analysis. The results showed that the seedling death rate was less than 7.5% when the flooding duration at the tillering stage was less than 2 days, which was not significantly different from control. As the flooding duration increased to 4–10 days, the death rate increased. When the flooding lasted more than 6 days, the death rate of early rice could reach more than 80% and even 100%. The death rate of Sixiang 1 reached 50% after flooding for 6 days while it was still smaller than 50% for Baixiang 139 after flooding for less than 10 days. The death rate was below 40% for the treatment of flooding at flowering stage. The initial heading stage time of flooding for 8 days was postponed compared with that of the control when flooding at different growth stages, and the heading duration was also prolonged. The yield was not significantly decreased when the flooding at the tillering stage lasted less than 4 days, but flooding for 6 days could result in the reduction of yield by 80% and flooding for 8–10 days could result in the death of plants. The yield reduction rate of flooding for 2 days at the booting and flowering stages was higher than 50%. The path analysis of yield components showed that the yield was mainly affected by effective panicles, seed-setting rate and 1 000-grain weight for the flooding at the tillering stage, by seed-setting rate, number of grains per panicle and 1 000-grain weight for the flooding at the booting stage, and by effective panicles and seed-setting rate for the flooding at the flowering stage, respectively. The study provides important information for formulating the flooding disaster warning system and management methods of double-cropping rice in Southwest China.
Before fruit thinning, the factors such as complex background, various illumination conditions, foliage occlusion, fruit clustering, especially the extreme similarities between apples and background, made the recognition of small apple targets very difficult. To solve these problems, we proposed a region-based fully convolutional network (R-FCN) recognition method. Firstly, the deep convolution neural network including ResNet-50 based on R-FCN and ResNet-101 based on R-FCN were studied and analyzed. After the framework of these two networks was analyzed, it was obvious that the difference between these two networks was the ‘conv4’ block. The ‘conv4’ block of ResNet-101 based on R-FCN was 51 more layers than that of ResNet-50 based on R-FCN, but the recognition accuracy of these two networks was almost the same. By comparing the framework and recognition result of ResNet-50 based on R-FCN and ResNet-101 based on R-FCN, we designed the R-FCN based on ResNet-44 to improve the recognition accuracy and simplify the network. The main operation to simplify the network was to simplify the ‘conv4’ block, and the ‘conv4’ block of ResNet-44 based on R-FCN was six layers fewer than that of ResNet-50 based on R-FCN. The Res Net-44 based on R-FCN consisted of ResNet-44 fully convolutional network (FCN), region proposal network (RPN) and region of interest (RoI) sub-network. Res Net-44 FCN, the backbone network of R-FCN, was used to extract the features of the image. The features were then used by RPN to generate RoIs. After that, the features extracted by ResNet-44 FCN and RoIs generated by RPN were used by RoI sub-network to recognize and locate small apple targets. A total of 3 165 images were captured in an experimental apple orchard in the College of Horticulture, Northwest A&F University, in Yangling City, China. After image resizing and manual annotation, 332 images, including 85 images captured under sunny direct sunlight condition, 88 images captured under sunny backlight condition, 86 images captured under cloudy direct sunlight condition, 74 images captured under cloudy backlight condition, were selected as test set, and the other 2 833 images were used to train and optimize the network. To enrich image training set, the data augment, including brightness enhancement and reduction, chroma enhancement and reduction, contrast enhancement and reduction, sharpness enhancement and reduction, and adding Gaussian noise, was performed, then a total of 28 330 images were obtained with 23 591 images randomly selected as the training sets, and the other 4 739 images as validation sets. After training, the simplified ResNet-44 based on R-FCN was tested on the test set, and the experimental results indicate that the method can effectively apply to the images captured under different illumination conditions. The method can recognize clustering apples, occluded apples, vague apples and apples with shadows, strong illumination and weak illumination on the surface. In addition, the apples divided into parts by branched or petiole cloud can also be recognized effectively. Overall, the recognition recall rate can achieve 85.7%. The recognition accuracy and false recognition rate are 95.2% and 4.9%, respectively. The average recognition time is 0.187 s per image. To further test the performance of the proposed method, we compared the other three methods, including Faster R-CNN, ResNet-50 based on R-FCN and ResNet-101 based on R-FCN. The
F1 of the proposed method is increased by 16.4, 0.7 and 0.7 percentage points, respectively. The average running time of the proposed method improves by 0.010 s and 0.041 s compared with that of Res Net-50 based on R-FCN and Res Net-101 based on R-FCN, respectively. The proposed method can achieve the recognition of small apple targets before fruits thinning which cannot be realized by traditional methods. It can also be widely applied to the recognition of other small targets whose features are similar to the background.
