Abstract. The self-propelled mower was designed to harvest the grass planted in mounted and hills, the copying device is the most critical mechanism of the mower, in order to improve the quality of the harvest, the reasonable design is needed. The copying device of self-propelled mower comprises a sliding palm, four bar mechanism, a lifting hydraulic cylinder and two springs, among them the springs are the most important part. According to the actual situation when mowers work, analyzed the strength and stiffness of the spring on the copying device, designed the spring diameter is 40 mm, the wire diameter is 10 mm and the spring circle is 12. The paper simulated the work condition of the spring by using ADAMS software, the results showed that the spring can meet the requirement of the design.
This paper proposes a new method to deal with visual information expression of image formation and systematization based on visual information representation theory, and analyzes the characteristics of multi-source remote sensing image from the perspective of remote sensing imaging mechanism, and expatiates some pivotal rules regarding visual information during image capturing, description and reconstruction. In the process of formulating SIFT description, this paper makes a detailed research on how to calculate the lower matching pints and marginal points, adjust the threshold of the feature matching parameters and increase the matching points numbers automatically, based on the number of the exiting matching points and their distribution conditions. In this experiment, the number of feature points increases with the decrease of the threshold of low contrast points, and edge response points, which shows the similar changes in the Law of Inverse; While in the process of automatic matching, the number of feature points increases with the increase of radio value of the farthest distance of the feature points to the nearest distance, showing almost directly proportional to the law. In general, as the number of matching points increase, the accuracy and the stability of the matching would decrease. This paper proposes a threshold weight of the adaptive algorithm to improve the accuracy and robustness of the matching points and solves the problems described above. Therefore, the multi-source remote sensing images are generally divided into the images with same resolution and those with different resolutions. When the reference image and the uncorrected image have the same resolution, the connection lines of the matching points will have the same distance and slope. By contract, when the resolution of the reference image and that of the uncorrected images are different, their connection lines of matching points will intersect. This paper, studying this geometric constraint conditions, suggests a fast mismatching points' rejected method based on rough fuzzy C-Means cluster theory. This paper then discusses the precise matching of residual matching points using Least Square Method. Numerous experiments are conducted for both aerial and satellite imageries under various conditions such as geometric distortion, illumination variation and different resolutions. Results of this study show that the proposed matching approach performs well, and the matching accuracy is stable and reliable.
Coordinated development of the Beijing-Tianjin-Hebei Region is a national strategy of China, while the most import aspect among the strategy is transportation integration. By using GF-1, ZY-3 satellite data, this paper produced the latest traffic infrastructure dataset, constructed the evaluation system of transportation superiority degree through the technical indicators such as the distribution of transportation infrastructure, the density of traffic network, the influence degree of traffic trunk line, and the location superiority degree. The results show that the transportation superiority degree in Beijing-Tianjin-Hebei Region presents a "bias normal" distribution characteristic. 14.8% of the county-level administrative units have outstanding transportation advantages, with better economic development. Near 9.4% of the county-level administrative units are at an obvious disadvantage in terms of traffic conditions, and about 75.7% units are at the middle or above the middle level of the evaluation samples. The results could be introduced to the transportation planning and supervision of this region.
Abstract. In order to analyze the drying characteristics of loofah, obtaining the optimal drying conditions. In this paper, the effects of different slice thickness and different temperature on the vacuum pulsation drying characteristics of loofah were studied by vacuum pulsation drying method. The drying kinetics of loofah was analyzed and the drying model was established. The results show that the smaller the slice thickness, the higher the temperature, the faster the drying rate. The drying process is deceleration drying, which is well fitted with the weibull model. The range of correlation coefficient R2 is 0.99516-0.99864, the effective diffusion coefficient is (1.88581~3.77767)x10-8, activation energy is 195kJ/mol. The results can provide theoretical support for the dry production of loofah.
Remote sensing change detection (CD) identifies changes in each pixel of certain classes of interest from a set of aligned image pairs. It is challenging to accurately identify natural changes in feature categories due to unstructured and temporal changes. This research proposed an effective bi-temporal remote sensing CD comprising an encoder that could extract multiscale features, a decoder that focused on semantic alignment between temporal features, and a classification head. In the decoder, we constructed a new convolutional attention structure based on pre-generation of depthwise-separable change-salient maps (PDACN) that could reduce the attention of the network on unchanged regions and thus reduce the potential pseudo-variation in the data sources caused by semantic differences in illumination and subtle alignment differences. To demonstrate the effectiveness of the PDA attention structure, we designed a lightweight network structure for encoders under both convolution-based and transformer architectures. The experiments were conducted on a single-building CD dataset (LEVIR-CD) and a more complex multivariate change type dataset (SYSU-CD). The results showed that our PDA attention structure generated more discriminative change variance information while the entire network model obtained the best performance results with the same level of network model parameters in the transformer architecture. For LEVIR-CD, we achieved an intersection over union (IoU) of 0.8492 and an F1 score of 0.9185. For SYSU-CD, we obtained an IoU of 0.7028 and an F1 score of 0.8255. The experimental results showed that the method proposed in this paper was superior to some current state-of-the-art CD methods.
The rotary blade is usually used as a soil-gashing tool to improve degenerated grassland in Chinese arid and semi-arid zones by breaking hardened soil layer without overturning soil. This kind of rotary blades has one sharpened side-edge only. When operating, this sharp edge can penetrate into soil to break the hardened layer. A mathematical model was developed to optimize the geometry of the blade with the goal of minimizing the torque. Experiments were conducted in a soil bin to verify the model and optimize design. Variables in this study included five different sliding cutting angles of the side-edge and three different section shapes of the blade. The Soil bin soil had similar soil textures with the grassland soil to be investigated, but there were no roots and other crop residues in the bin soil. The blade was operated at a constant speed of 0.6m/s, rotational speed of 300rpm and depth of 200mm. A torque sensor was used to measure the torque of the driving shaft. The results of mathematical model and experiment indicated that the torque requirements were significantly affected by the cutting angle of the side-edge and section shape. Test results indicated that the blade with sliding cutting angles from 46to 51had the lowest torque requirements. Different section shapes of blades requested significantly different torques, and optimal shape was determined.
Based on measurement data from air quality monitoring stations, the spatio-temporal characteristics of the concentrations of particles with aerodynamic equivalent diameters smaller than 2.5 and 10 μm (PM2.5 and PM10, respectively) in the Beijing–Tianjin–Hebei (BTH) region from 2015 to 2018 were analysed at yearly, seasonal, monthly, daily and hourly scales. The results indicated that (1) from 2015 to 2018, the annual average values of PM2.5 and PM10 concentrations and the PM2.5/PM10 ratio in the study area decreased each year; (2) the particulate matter (PM) concentration in winter was significantly higher than that in summer, and the PM2.5/PM10 ratio was highest in winter and lowest in spring; (3) the PM2.5 and PM10 concentrations exhibited a pattern of double peaks and valleys throughout the day, reaching peak values at night and in the morning and valleys in the morning and afternoon; and (4) with the use of an improved sine function to simulate the change trend of the monthly mean PM concentration, the fitting R2 values for PM2.5 and PM10 in the whole study area were 0.74 and 0.58, respectively. Moreover, the high-value duration was shorter, the low-value duration was longer, and the concentration decrease rate was slower than the increase rate.
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