The pneumatic artificial muscle (PAM)'s development history and recent research achievements of main domestic and overseas organizations are reviewed. Research work in basic characteristics and modeling,structure optimization and control strategy are summarized. The results indicate that PAM can be modeled from several aspects such as the equivalent work and elasticity theory; its performance is improved through various structure optimizations; different control strategies such as robust design,adaptive control,and intelligent control are adopted according to different PAM system characteristics. Judging from the current development trend,the PAM's working mechanism analysis and high accuracy control are difficult to have a breakthrough in short term. Comparatively,the new structural design and application work will grow rapidly. A broad application can be expected in the fields of bionics,physical therapy,virtual reality and so on.
The individual identification of pigs is the basis for precision livestock farming (PLF), which can provide prerequisites for personalized feeding, disease monitoring, growth condition monitoring and behavior identification. Pig face recognition has the problem that pig face samples are difficult to collect and images are easily affected by the environment and body dirt. Due to this problem, we proposed a method for individual pig identification using three-dimension (3D) point clouds of the pig's back surface. Firstly, a point cloud segmentation model based on the PointNet++ algorithm is established to segment the pig's back point clouds from the complex background and use it as the input for individual recognition. Then, an individual pig recognition model based on the improved PointNet++LGG algorithm was constructed by increasing the adaptive global sampling radius, deepening the network structure and increasing the number of features to extract higher-dimensional features for accurate recognition of different individuals with similar body sizes. In total, 10,574 3D point cloud images of ten pigs were collected to construct the dataset. The experimental results showed that the accuracy of the individual pig identification model based on the PointNet++LGG algorithm reached 95.26%, which was 2.18%, 16.76% and 17.19% higher compared with the PointNet model, PointNet++SSG model and MSG model, respectively. Individual pig identification based on 3D point clouds of the back surface is effective. This approach is easy to integrate with functions such as body condition assessment and behavior recognition, and is conducive to the development of precision livestock farming.
This study presents the impact of rice straw as additive material on physical properties of hollow block as compressive, flexural strength and water absorption, Softening coefficient. Through testing the hollow block physical properties, the of rice straw additive was studied. When the rice straw amount portion was 0~15%, with rice straw amount portion increased, compressive, flexural strength and water resistance effect of adding one kind of early strength agent and mixing Al2(SO4)3, CaCl2 early strength agent hollow block decreased gradually. When the rice straw amount portion was 10%, adding early strength agent Al2(SO4)3, CaCl2 ，the 28d compressive strength of hollow block was minimum, 3.5MPa; while mixing CaCl2, Al2(SO4)3 early strength agent, the hollow block softening coefficient was 0.76, water absorption rate was 3.9%, meet the requirements of national standard of common concrete hollow block. Through the experiment, the conclusion is mixing early strength agent Al2(SO4)3, CaCl2, Obviously superior to adding one kind of —early strength agent—Al2(SO4)3 or CaCl2 on the physical properties of hollow block.
In the field of TD-LTE network problem analysis, compared with traditional methods such as DT(Driver Test) and CQT(Call Quality Test), MR (Measurement Report) has the advantages of comprehensive information and high efficiency, begins to get more and more attention and application. In order to solve the problem of limited open time of measurement data acquisition system, a data prediction method based on LSTM (Long Short-Term Memory) model is proposed. Selecting part of the MR parameters as the experimental object, training LSTM Model with measurement data in a district of Beijing. Experimental results show that the proposed method can predict MR data accurately. Compared with the traditional prediction model ARIMA (Autoregressive Integrated Moving Average Model), this method has lower prediction error and more stable generalization ability.
The current standard Unified Modeling Language(UML) could not model framework flexibility and extendability adequately due to lack of appropriate constructs to distinguish framework hot-spots from kernel elements. A new UML profile that may customize UML for framework modeling was presented using the extension mechanisms of UML, providing a group of UML extensions to meet the needs of framework modeling. In this profile, the extended class diagrams and sequence diagrams were defined to straightforwardly identify the hot-spots and describe their instantiation restrictions. A transformation model based on design patterns was also put forward, such that the profile based framework design diagrams could be automatically mapped to the corresponding implementation diagrams. It was proved that the presented profile makes framework modeling more straightforwardly and therefore easier to understand and instantiate.
Leaf vein features play an important role in botanical studies. It is also a significant and challenging task in the field of computer vision. This paper proposes a new method of leaf vein extraction and angle measurement. The angle is between the primary vein and the secondary vein. We focus on the leaves whose leaf veins are straight. The algorithm's procedure is as follows: first, through contour extraction we segment foreground and background, get clean images of leaves. Second, change the color space from RGB to HSI, separate the hue component and enhance it. Third, get adaptive thresholds for canny detection based on Otsu algorithm. Then using canny edge detection and Hough transform to detect lines, most of them are leaf veins. We need to select the right lines. And finally we can get the angles between the primary vein and the secondary veins through these lines. Experiments have been conducted with a lot of leaf images. Experimental results show that this method can be used to extract leaf veins and measure angles, even when leaf veins are a little blurry.
After analyzing the features and requirements of automatic test system, an object model and a dynamic model described with the unified modeling language (UML) were presented. As a result, a systematic object-oriented framework for automatic test system came into being. In contrast to the conventional function-based representation model, this framework can describe the object structure and behavior of automatic test system more completely, and is characterized by higher productivity, better reusability, maintainability and extendability. This framework can serve as both a modeling basis and a practical tool for description, analysis and design of the automatic test system, and particularly for computer aided analysis and design of automatic test system. Based on this reusable and extendable framework, the software development efficiency for automatic test systems can be evidently increased.
According to the analysis of quantity of chlorophyll a and physicochemical factors in the water of the West Lake, results show that the algae growth in Beili area, Yue area, Xili area and Wai area is mainly affected by the water temperature, but not limited by the concentration of N and P in the water. However, the water quality in Xiaonan area is better than other lake areas, because it lies in the diversion entrance and directly influenced by the drawing water from the Qiantang River. The studies on biological control experiments suggest that a reasonable and coordinated ecological system would play an important role in improving the water quality of the West Lake.
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