激光晶体Nd:YVO4的形貌及生长缺陷

本文报道了应用环境扫描电镜（ESEM）和同步辐射X射线白光形貌术对采用提拉法生长出的Nd:YVO4晶体进行的形貌及生长缺陷的分析,获得了该晶体的开裂表面的ESEM形貌像以及取自晶体肩部和中间部位的（001）面的同步辐射白光形貌像,观察到了位错、包裹物等缺陷,可为生长高质量的Nd:YVO4晶体提供重要的启示.     

美国C.F布朗公司大型合成氨装置用材简介

介绍了美国Ｃ．Ｆ布朗公司大型合成氨装置根据操作条件和介质腐蚀程度不同，如何选择管道和设备材料，并对其用材进行逐一剖析。     

Cervid Prion Protein Polymorphisms: Role in Chronic Wasting Disease Pathogenesis

Chronic wasting disease (CWD) is a prion disease found in both free-ranging and farmed cervids. Susceptibility of these animals to CWD is governed by various exogenous and endogenous factors. Past studies have demonstrated that polymorphisms within the prion protein (PrP) sequence itself affect an animal’s susceptibility to CWD. PrP polymorphisms can modulate CWD pathogenesis in two ways: the ability of the endogenous prion protein (PrP^C) to convert into infectious prions (PrP^Sc) or it can give rise to novel prion strains. In vivo studies in susceptible cervids, complemented by studies in transgenic mice expressing the corresponding cervid PrP sequence, show that each polymorphism has distinct effects on both PrP^C and PrP^Sc. It is not entirely clear how these polymorphisms are responsible for these effects, but in vitro studies suggest they play a role in modifying PrP epitopes crucial for PrP^C to PrP^Sc conversion and determining PrP^C stability. PrP polymorphisms are unique to one or two cervid species and most confer a certain degree of reduced susceptibility to CWD. However, to date, there are no reports of polymorphic cervid PrP alleles providing absolute resistance to CWD. Studies on polymorphisms have focused on those found in CWD-endemic areas, with the hope that understanding the role of an animal’s genetics in CWD can help to predict, contain, or prevent transmission of CWD.     

Robust consensus algorithm for multi-agent systems with exogenous disturbances under convergence conditions

In this paper, a robust consensus algorithm is developed and sufficient conditions for convergence to consensus are proposed for a multi-agent system (MAS) with exogenous disturbances subject to partial information. By utilizing H_∞ robust control, differential game theory and a design-based approach, the consensus problem of the MAS with exogenous bounded interference is resolved and the disturbances are restrained, simultaneously. Attention is focused on designing an H_∞ robust controller (the robust consensus algorithm) based on minimisation of our proposed rational and individual cost functions according to goals of the MAS. Furthermore, sufficient conditions for convergence of the robust consensus algorithm are given. An example is employed to demonstrate that our results are effective and more capable to restrain exogenous disturbances than the existing literature.     

Observer-based networked control with probabilistic interval input delays

In this paper, the problem of observer-based control is investigated for networked control systems (NCSs) with probabilistic interval distribution communication delays. In the presence of network-induced delays and packet dropouts in the sensor-to-controller and controller-to-actuator connections, a new model for an observer-based NCS is established, which is then converted to an equivalent linear system with two random time-varying delays satisfying Bernoulli distributions. By utilizing information concerning the probability distribution of the delays and by adopting a tighter bounding technique, less conservative asymptotic mean-square stable sufficient conditions are derived in the form of linear matrix inequalities (LMIs). Numerical examples are provided to demonstrate the effectiveness of the proposed method.     

可解释的基于图嵌入的Android恶意软件自动检测

Android恶意软件的几何式增长驱动了Android恶意软件自动检测领域的发展。一些工作从可解释性的角度来分析Android恶意软件,通过分析模型获取最大影响的特征,为深度学习模型提供了一定的可解释性。这些方法基于特征相互独立的强假设,仅仅考虑特征各自对模型的影响,而在实际中特征之间总是存在着耦合,仅考虑单个特征对模型的影响,难以反映耦合作用,不能刻画不同类型软件中敏感API的组合模式。为解决该问题,将Android软件刻画成图,并结合图的结构信息和图节点内部的信息提出了一种基于图嵌入的方法来检测Android恶意软件。该方法通过注意力机制学习Android软件的低维稠密嵌入表示。实验结果表明,使用学到的嵌入表示进行恶意软件检测,不仅具有较高的分类精度,还可以通过分析注意力分数较大的路径寻找影响模型决策的模式以及定位恶意行为所涉及的敏感API序列。     

Combining the wavelet and second order total generalized variation for the image zooming algorithm

A new image zooming model combining the wavelet and second order total generalized variation is proposed. The original image is regarded as the wavelet low-frequency band for the zoomed image, and the high-frequency bands are estimated. Further processing is implemented for the zoomed image using the second order total generalized variation. The second order total generalized variation may lead to an absence of the staircase effect and keep most details, and therefore, the high quality image is reconstructed. Finally, experimental results have illustrated that our algorithm not only can achieve better zooming but also can produce a very satisfactory denoising effect.     

Static and dynamic compressive properties of polypropylene/zinc oxide nanocomposites

The effect of strain rate is widely recognized as an essential factor that influences the mechanical properties of polymer matrix composites. Despite its importance, no previous work has been reported on the high‐strain rate behavior of polypropylene/zinc oxide nanocomposites. Based on this, static and dynamic compression properties of polypropylene/zinc oxide nanocomposites, with particle contents of 1%, 3%, and 5% by weight, were successfully studied at different strain rates (i.e., 0.01 s^?1, 0.1 s^?1, 650 s^?1, 900 s^?1, and 1100 s^?1) using a universal testing machine and a split Hopkinson pressure bar apparatus. For standardization, approximately 24 nm of zinc oxide nanoparticles were embedded into polypropylene matrix for each of the tested polypropylene/zinc oxide nanocomposites. Results show that the yield strength, the ultimate strength, and the stiffness properties, of polypropylene/zinc oxide nanocomposites, were greatly affected by both particle loading and applied strain rate. Furthermore, the rate sensitivity and the absorbed energy of all tested specimens showed a positive increment with increasing strain rate, whereas the thermal activation volume showed a contrary trend. In addition, the fractographic analysis and particle dispersion of all composite specimens were successfully obtained using a field emisission scanning electron microscopy. POLYM. ENG. SCI., 54:949–960, 2014. © 2013 Society of Plastics Engineers     

A Short Review on Copper Calcium Titanate (CCTO) Electroceramic: Synthesis,Dielectric Properties,Film Deposition,and Sensing Application

Nano-Micro Letters - Electroceramic calcium copper titanates (CaCu3Ti4O12, CCTO), with high dielectric permittivities (ε) of approximately 105 and 104, respectively, for single crystal and...     

高校后勤物业管理的改革方向探析

从高校的物业管理的特点出发,分析了当前我国高校物业管理改革的现状,总结了各高校在物业管理中存在的问题,并结合成功典范,提出了物业管理的改革方向和策略,有助于高校物业管理水平的提高。