课程文献中心 更多>>

关键词： 摇摆式自动旋转喷枪   扬尘监测   道路扬尘治理  

摘要： 本文以矿山运输道路扬尘治理装置中存在的问题,探索使用新型摇摆式自动旋转喷枪、扬尘监测等多种新技术新产品应用到道路定时喷洒水降尘的方法,解决原系统中水压低、洒水不均匀、覆盖面积小、装置故障率高等问题,为矿山道路扬尘治理探索出了可推广应用的方法。

关键词： n-port network   eventual positivity   signed Laplacians   spectral properties   Kron reduction  

摘要： Signed graphs have appeared in a broad variety of applications, ranging from social networks to biological networks, from distributed control and computation to power systems. In this article, we investigate spectral properties of signed Laplacians for undirected signed graphs. We find conditions on the negative weights under which a signed Laplacian is positive semidefinite via the Kron reduction and multiport network theory. For signed Laplacians that are indefinite, we characterize their inertias with the same framework. Furthermore, we build connections between signed Laplacians, generalized M-matrices, and eventually exponentially positive matrices.

关键词： Fractional partial differential equations   Perfectly matched layers   Fourier pseudospectral approximation   Time splitting scheme   Finite difference  

摘要： This paper is devoted to the derivation and analysis of accurate and efficient perfectly matched layers (PMLs) or efficient absorbing layers for solving fractional Laplacian equations within initial boundary value problems (IBVP). Two main approaches are derived: we first propose a Fourier-based pseudospectral method, and then present a real space method based on an efficient computation of the fractional Laplacian with PML. Some numerical experiments and analytical results are proposed along the paper to illustrate the presented methods.

关键词： Quantum mechanics   Electromagnetic interaction   Magnetoelectric effect   Maxwell modified equations   Massive electrodynamics  

摘要： Quantum equations describing a moving charged quantum particle are derived. The electric nature is described by the current and charge densities, (J) over bar and rho;and the quantum nature by the particle mass, wavefunctions, (psi) over bar and psi(0). The vector wavefunction, (psi) over bar is found to act along the current direction. The energy of the matter fields concomitant with a particle is found to flow along the current direction. A fluid with a stationary mass density inherently exhibits a Thomas precession.

关键词： Satellite cloud images   Heavy rainfall   Laplacian eigenmaps   Random forest algorithm   Multiple linear regression  

摘要： The recent emergence of satellite detection and imaging technologies has increased the demand for the application of satellite cloud images to current weather forecasting. However, approaches based on nonlinear prediction technology to forecast satellite images are lacking, and forecasting timelines are relatively short, e.g., 1-3 h in advance. In the present study, a nonlinear dimensionality reduction approach based on Laplacian eigenmaps (LEs) was combined with a random forest (RF) algorithm to construct an intelligent computing prediction model for rainstorm satellite images obtained from the first annual rainy season (April-June) in South China from 2010 to 2018. Results showed that the proposed forecasting model based on nonlinear intelligent calculation can accurately predict the key features and trends of the development and movement of strong precipitation clouds. The predicted satellite images described by the model were also consistent with the major features of the observed satellite images. This study then used a multiple linear regression (MLR) method based on the same prediction factors to establish a model for predicting satellite images for the same modeling and forecasting samples. Comparative results of the two prediction schemes showed that the LE + RF algorithm satellite image prediction scheme yields more samples exhibiting a high correlation with observed satellite images than the MLR method. Compared with that of the proposed scheme, the amount of samples of the MLR scheme in the low-correlation area was significantly larger. In general, the nonlinear intelligent computing scheme developed in this study is superior to the MLR method for predicting satellite cloud images. Thus, the LE + RF algorithm satellite image prediction scheme provides an objective and practical method for observed satellite cloud image predictions.

摘要： Transparent conducting films (TCFs) are films of optically transparent and electrically conductive material. TCFs are typically used as electrodes in photovoltaic applications like solar cells, liquid-crystal displays (LCDs), etc. that call for low resistance electrical contacts while not blocking the incident light. Doped metal oxides are the most important TCFs since their conductivity and band gap can be tuned through doping. Indium tin oxide (ITO) or tin-doped indium oxide is the most widely used owing to its excellent optoelectronic properties and ease of fabrication. Solution processing is a simple and cost- effective approach to deposit thin films under ambient conditions with minimum material wastage. In this research, transparent conducting films of ITO were deposited on soda-lime glass and sheet glass substrates using a sol-gel ITO ink. Two deposition techniques, spin coating and inkjet printing were used to deposit single and multilayer ITO films. The processing parameters evaluated include the spin coating speed, inkjet printing drop spacing, ink concentration, temperature, and humidity of the ambient. The results were optimized to achieve the lowest sheet resistance and impedance magnitude for single layer ITO films while maintaining high optical transparency and uniform surface morphology. High humidity values were found to affect the substrate wetting property of the ITO ink and increased the possibility of hydrolysis during deposition, resulting in the formation of non-uniform surface patterns. A speed of 4000 rpm or more in the case of spin coating and a drop spacing of 150 µm or more in the case of inkjet printing are required to obtain a uniform ITO film with desirable electrical and optical properties. Once the optimum combination of parameters is obtained, the sheet resistance and impedance magnitude can be reduced by more than two orders of magnitude through multilayer deposition and annealing in a reducing environment with minimal effect on th

关键词： Dissipative particle dynamics  

摘要： Normal red blood cells (RBCs) have remarkable properties of deformability, which enable them to squeeze through tiny splenic inter-endothelial slits (IESs) without any damage. Decreased surface-area-to-volume (SA/V) ratio through the loss of membrane surface is a key determinant of splenic entrapment of surface-altered RBCs due to cell aging or disease. Here, we investigate the flow dynamics and mechanical retention of the surface-altered RBCs with different extents of surface area loss, using a multiscale RBC (MS-RBC) model implemented in dissipative particle dynamics (DPD). We show that the DPD-based MS-RBC simulations can accurately reproduce the ex vivo experimentally measured rate of RBC mechanical retention when we take into account the distribution of RBC surface area (i.e., the size difference within the RBC population). We also examine the cumulative effect of the cell surface area loss on the traversal dynamics of the surface-altered RBCs, where we found that the final values of cell surface area (or the SA/V ratio) play a key role in determining the RBC traversal dynamics, regardless of the loss pathway of cell surface area. Taken together, these simulation results have implications for understanding the sensitivity of the splenic IESs to retain and clear the surface-altered RBCs with increased surface area loss, providing an insight into the fundamental flow dynamics and mechanical clearance of the surface-altered RBCs by the human spleen.

关键词： 潜能  

ISBN: (纸本)9787513074209

摘要： 本书作者提出了一套新的哲学理论——潜能论，并从潜能的观点出发，对哲学的几个基本问题进行透视性解析。书中作者还针对一些历史、文化问题进行了哲学反思，这些思考都收录在第一部分(潜能论)后的二三部分的短篇里，可以看作是潜能论的注脚。

关键词： Diffusion magnetic resonance imaging   Glioma   Corticospinal tract   Muscle weakness  

摘要： Objective: To evaluate the application of laplacian-regularized mean apparent propagator (MAPL)-MRI to brain glioma-induced corticospinal tract (CST) injury. Materials and Methods: This study included 20 patients with glioma adjacent to the CST pathway who had undergone structural and diffusion MRI. The entire CSTs of the affected and healthy sides were reconstructed, and the peritumoral CSTs were manually segmented. The morphological characteristics of the CST (track number, average length, volume, displacement of the affected CST) were examined and the diffusion parameter values, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), mean squared displacement (MSD), q-space inverse variance (QIV), return to-origin probability (RTOP), return-to-axis probabilities (RTAP), and return-to-plane probabilities (RTPP) along the entire and peritumoral CSTs, were calculated. The entire and peritumoral CST characteristics of the affected and healthy sides as well as those relative CST characteristics of the patients with motor weakness and normal motor function were compared. Results: The track number, volume, MD, RD, MSD, QIV, RTAP, RTOP, and RTPP of the entire and peritumoral CSTs changed significantly for the affected side, whereas the AD and FA changed significantly only in the peritumoral CST (p < 0.05). In patients with motor weakness, the relative MSD of the entire CST, QIV of the entire and peritumoral CSTs, and the AD, MD, RD of the peritumoral CST were significantly higher, whereas the RTPP of the entire and peritumoral CSTs and the RTOP of the peritumoral CST were significantly lower than those in patients with normal motor function (p < 0.05 for all). In contrast, no significant changes were found in the CST morphological characteristics, FA, or RTAP (p > 0.05 for all). Conclusion: MAPL-MRI is an effective approach for evaluating microstructural changes after CST injury. Its sensitivity may improve when using

关键词： 53C10   53C30   53C44  

摘要： We study the Laplacian flow of a G(2)-structure where this latter structure is claimed to be locally conformal parallel. The first examples of long time solutions of this flow with the locally conformal parallel condition are given. All of the solutions are ancient and Laplacian soliton of shrinking type. These examples are one-parameter families of locally conformal parallel G(2)-structures on rank-one solvable extensions of six-dimensional nilpotent Lie groups. The found solutions are used to construct long time solutions to the Laplacian coflow starting from a locally conformal parallel structure. We also study the behavior of the curvature of the solutions obtaining that for one of the examples the induced metric is Einstein along all the flow (resp. coflow).