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Abstract Temporal satellite networks can accurately describe the dynamic process of satellite networks by considering the interaction relationship and interaction sequence between satellite nodes. In addition, the measurement of n...
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Abstract Temporal satellite networks can accurately describe the dynamic process of satellite networks by considering the interaction relationship and interaction sequence between satellite nodes. In addition, the measurement of node importance in satellite networks plays a crucial role in understanding the structure and function of the network. The classical supra-adjacency matrix (SAM) temporal model identifies the key nodes in the temporal network to some extent, which ignores the differences of inter-layer connectivity relationships leading to the inability to reflect the dynamic variations of satellite nodes. Therefore, the evaluation method based on time slot correlation is proposed to measure the importance of satellite nodes in this paper. Firstly, the correlation coefficient of time slot nodes is defined to measure the coupling relationship of adjacent time slots. Secondly, the dynamic supra-adjacency matrix (DSAM) temporal network model is proposed considering the correlation between adjacent time slots and the characteristics of link time. Finally, the node importance ranking results in each time slot and a global perspective are obtained by utilizing the eigenvector centrality. Experimental simulations of the Iridium and Orbcomm constellations demonstrate that the DSAM method has a relatively accurate recognition rate and high stability.
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Recombinant immunotoxins (RITs) are proteins that contain a toxin fused to an antibody or small molecules and are constructed by the genetic engineering technique. RITs can bind to and be internalized by cells and kill cancerous o...
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Recombinant immunotoxins (RITs) are proteins that contain a toxin fused to an antibody or small molecules and are constructed by the genetic engineering technique. RITs can bind to and be internalized by cells and kill cancerous or non-cancerous cells by inhibiting protein synthesis. A wide variety of RITs have been tested against different cancers in cell culture, xenograft models, and human patients during the past several decades. RITs have shown activity in therapy of several kinds of cancers, but different levels of side effects, mainly related to vascular leak syndrome, were also observed in the treated patients. High immunogenicity of RITs limited their long-term or repeat applications in clinical cases. Recent advances in the design of immunotoxins, such as humanization of antibody fragment, PEGylation, and modification of human B- and T-cell epitopes, are overcoming the above mentioned problems, which predict the use of these immunotoxins as a potential therapeutic method to treat cancer patients.
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Street trees on both sides of the road are one of the important infrastructures of a city. Automatic extraction of street trees is of great significance in the fields of smart cities and smart transportation. Mobile laser system (...
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Street trees on both sides of the road are one of the important infrastructures of a city. Automatic extraction of street trees is of great significance in the fields of smart cities and smart transportation. Mobile laser system (MLS) enables efficient access to object point clouds around the city roads, providing a high-quality data source for the extraction of street trees. Thus, this paper proposes a refined method for extracting street trees in MLS point clouds data in order to achieve the extraction of the point clouds of a single street tree in the complex urban road environment. First, an identification method for the pole-like parts is designed based on the hierarchical semantic features of the pole-like target. Then an estimating method of point clouds dimension features is designed through analyzing a top-down searching and estimating strategy. The method distinguishes the category by the features of the upper point clouds of the pole-like objects and identifies the artificial pole-like objects and the tree point clouds based on the regional growth based on the category constraint. Finally, to solve the problem of segmenting connected tree crowns, this study designs a segmentation method based on curve fitting of the crown contour, taking into full consideration of the geometric features of the?tree crown contour. This method realizes a refined segmentation of connected tree crowns and finally obtains a complete single street tree object. The experimental result shows that the method has a great effect on street tree extraction in different urban road environments.
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Friction nonlinearity, which is common in electromechanical actuator (EMA) systems, leads to undesired dynamic responses such as “flat top”, low-speed crawl, which brings challenges to high precision attitude control of flight v...
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Friction nonlinearity, which is common in electromechanical actuator (EMA) systems, leads to undesired dynamic responses such as “flat top”, low-speed crawl, which brings challenges to high precision attitude control of flight vehicles. In order to improve the robustness of the actuator control system under friction nonlinearity, and suppress the chattering caused by high gain of sliding mode control (SMC), a composite SMC scheme based on modified extended state observer (MESO) is proposed. Nonlinear MESO is adopted for estimating the nonlinear friction dynamics, unmodeled disturbance, and external real-time load dynamics so as to compensate for their adverse effect. At the same time, in order to improve the robustness of EMA, and reduce the tracking error of the servo system, SMC is adopted to ensure the tracking error convergence in a finite time. The stability of the proposed method is proved, and the effectiveness is verified by simulations.
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Highway traffic increasingly extends to the mountainous area, requiring highway tunnels to be longer. Highway tunnel construction is risky and challenging, especially in the high ground temperature area of Western China. In this s...
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Highway traffic increasingly extends to the mountainous area, requiring highway tunnels to be longer. Highway tunnel construction is risky and challenging, especially in the high ground temperature area of Western China. In this study, the Nige Tunnel of Yunnan Honghe Jian(ge) Yuan highway is the research object. By conducting numerous field temperature tests, geological surveys, water quality experiments, and other processes, the causes of high temperatures in the ground have been analyzed. The results show that the hot liquid or vapor from the earth's crust deep area carries various chemical materials, passing through various channels (faults and fissures) to the superficial area and forms the geothermal of the tunnel. The thermal anomaly bodies in the deep crust move upward through faults Fn1 and Fn2. Some heat sources are exposed to the surface and form hot springs, and others are distributed through secondary channels after being transmitted to the shallow part of the crust. Among them, the entrance section of the Nige Tunnel is limestone, and the groundwater infiltrating the fracture channel is mixed in the conduction process, resulting in the overall low water temperature, and the rock wall temperature is lower than the water body temperature. The exit section of the Nige Tunnel is granite, the heat source is mainly conducted through structural fractures or rock mass, resulting in high rock temperature at the exit. By analyzing the causes of high ground temperature, this study provides a theoretical basis for developing the tunnel scheme.
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Materials and structures in practical engineering inevitably subject to dynamic loads. Surface and internal discontinuities have signification effects on wave propagation and may cause dynamic stress concentration in the vicinity ...
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Materials and structures in practical engineering inevitably subject to dynamic loads. Surface and internal discontinuities have signification effects on wave propagation and may cause dynamic stress concentration in the vicinity of them. Thus, it is of great significance to determine the dynamic response of materials and structures with surface and internal features under elastic waves. In this article, based on the wave function expansion method, the image method and the complex function method, an analytical solution is presented for the scattering of anti-plane (SH) waves by multiple cylindrical elastic inclusions and semi-cylindrical depressions in an elastic infinite plate. The series expressions of the displacement fields, stress fields, and dynamic stress concentration factors around the inclusion and the depression are derived. Numerical calculations show that the incident wavenumber, shear modulus of the inclusion, plate thickness, and relative position between the inclusion and the depression express great effects on the dynamic stress concentration. The theoretical solutions of this article can provide a reference for the results of numerical methods. And the findings are useful for structural design and nondestructive testing of the plate.
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Aluminum (Al) nanoparticle (ANP), as a metal fuel agent, has excellent combustion rate and energy density. However, several critical research gaps of ANP still exist. This study is focused on the annealing properties of ANP and it...
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Aluminum (Al) nanoparticle (ANP), as a metal fuel agent, has excellent combustion rate and energy density. However, several critical research gaps of ANP still exist. This study is focused on the annealing properties of ANP and its coating performances under the mixture of ethanol and ether molecules. According to those obtained molecular dynamic (MD) simulation results, the microstructure of ANP in the annealing process and the formation of ethanol–ether binary coating are discussed in this paper. During the melting process, the melting point of ANP could be analyzed by the inflection point of its atomic potential energy and the mean square displacement, then the accuracy of EAM force field could be verified. Because surface atoms have lower potential energy than inner atoms, it seems that the melting of ANP started from the particle surface and diffuses from surface to the core. When the melted Al cluster is solidified until 300?K, the microstructure of the crystallized particle is largely affected by the cooling rate. If the cooling rate if too fast, it is not enough for the Al cluster to recrystallize, which is called as the “freezing effect” for ANP. Next, the binary “competitive adsorption” behavior of ethanol and ether on the surface of ANP was simulated according to different ethanol–ether molecular ratios. Analyses of ethanol–ether binary coating layer show that the main component of binary coating is ethanol, but not ether. This competitive superiority of ethanol is caused by its own adsorption mechanism and molecular migration in this mixture of ethanol and ether.
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Abstract The subway sliding plug door system has been opened and closed frequently for a long time under variable working conditions, and multiple failures are prone to occurring and resulting in train shutdowns and even major saf...
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Abstract The subway sliding plug door system has been opened and closed frequently for a long time under variable working conditions, and multiple failures are prone to occurring and resulting in train shutdowns and even major safety accidents. Due to the complex physical mechanism of the sliding plug door system, it is difficult for a single signal to accurately represent the failure states of the sliding plug door system. Thus, identifying the multiple failure causes of the subway sliding plug door system has become a challenging problem. Aiming at the problem, an equipment multiple failure causes intelligent identification method based on an integrated strategy is proposed for the subway sliding plug door system under variable working condition. In the proposed method, firstly, the sensitive features that can reflect the degradation state of equipment are obtained by using the random forest to measure the importance of fetatures and sort them. Secondly, feature dimensionality is reduced by using t-distributed stochastic neighbor mbedding (TSNE) to map the screened high-dimensional features to low-dimensional space. Finally, the parameters of the extreme learning machine (ELM) are optimized by using the particle swarm optimization (PSO) algorithm to build a multiple failure causes classification model. The proposed method is verified by the 1:1 benchmark test data of the subway sliding plug door system. The results show that the proposed method has higher classification accuracy, faster calculation speed, and stronger generalization ability. The proposed method is an effective integrated strategy to identify multiple failure causes in the subway sliding plug door system and guide the health management and operational maintenance of the subway sliding plug door system.
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The aim of this article is to investigate the scattering of anti-plane shear waves by elliptic notches in a quarter-space piezoelectric material. The wave field and electric field expressions in this region are derived using the w...
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The aim of this article is to investigate the scattering of anti-plane shear waves by elliptic notches in a quarter-space piezoelectric material. The wave field and electric field expressions in this region are derived using the wave function expansion method. An infinite linear system of equations is established by applying the boundary conditions of no traction and no potential. The results obtained are accurate due to the good convergence of the wave function. The displacement amplitude and dynamic stress in the vicinity of the elliptic arc notch under different characteristic parameters and different wave numbers are computed numerically.
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Osteoarthritis (OA) is one of the most common chronic diseases, causing degenerative changes in articular cartilage and subchondral bones. To date, there is no effective drug to delay the progression of OA in clinical practice. In...
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Osteoarthritis (OA) is one of the most common chronic diseases, causing degenerative changes in articular cartilage and subchondral bones. To date, there is no effective drug to delay the progression of OA in clinical practice. In this study, we synthesized and prepared a new thermosensitive hydrogel called PHA hydrogel, a mixture of normal poloxamer 407 and hyaluronic acid-modified poloxamer 407, and we investigated the effects of the PHA hydrogel loaded with keratinocyte growth factor 2 (KGF-2) on rats with papain-induced OA. First, we evaluated the safety of the PHA hydrogelin vitroandin vivo. The results showed that the PHA hydrogel had suitable osmotic pressure and no obvious cytotoxicity or adverse reactions after intra-articular injection. In addition, the PHA hydrogel improved the stability of KGF-2. Next, we studied the effects of the PHA hydrogel loaded with KGF-2 (PHA-KGF-2) on OA in rats. PHA-KGF-2 significantly improved the morphology and inflammation of the articular cartilage, reduced the loss of proteoglycan, and balanced collagen metabolism compared with KGF-2 alone. These data demonstrated that the PHA hydrogel is a safe biomaterial that can protect KGF-2, and thus is a promising therapeutic strategy for patients with OA.
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