上海电网负荷低电压释放问题的研究

对影响上海电网低电压释放的诸因素作了全面细致的分析,提出了相应的对策.对低电压不释放对系统的影响也作了定性讨论.研究的结论对城市密集型电网具有普遍指导意义.     

Study of oxidation behavior of nanostructured NiCrAlY bond coatings deposited by cold spraying

Nanostructured NiCrAlY bond coating was deposited using a milled powder by cold spraying. A shot-peening treatment was then applied to the as-sprayed coating to modify the coating surface morphology. The oxidation behavior of the coating with the as-sprayed surface and shot-peened surface was investigated under isothermal oxidation at 900 °C and 1000 °C for different times. The oxidation behavior of the coating was characterized through surface morphology and cross-sectional microstructure by scanning electron microscopy. It was found that a uniform oxide layer was formed on the surface of the shot-peened nanostructured NiCrAlY coating during oxidation at temperatures of 900 °C and 1000 °C. The surface morphology of the coating has significant effect on the morphology of the oxide. The surface geometry of the cold-sprayed MCrAlY coating must be modified to promote formation of a protective oxide film during oxidation, through application of a post-treatment process such as shot-peening.     

苹果罐头加工工艺探讨

本文对影响苹果罐头质量的因素进行了研究,对传统工艺中的去皮、抽空等步骤提出了改进意见。     

拱坝裂缝开展有限元分析

本文提出一个数学模型,用于拱坝裂缝开展分析,所需机时省,内存要求较小,精度好。文末给出一算例,用以说明方法的特点及拱坝裂缝开展分析的意义。     

在横向气流中螺旋管管阵动态响应的研究

对螺旋管管阵在横向气流冲刷下的振动响应进行了实验研究，所获得管子的加速度、速度和位移信号为螺旋管流弹不稳定性的研究提供了数据基础     

A microcomputer-based distributed data management system for a large cooperative study of transfusion associated acquired immunodeficiency syndrome

This paper describes the details of a microcomputer-based, distributed data management system in the acquisition of data collected in a large multicentered cooperative investigation of transfusion-transmitted acquired immunodeficiency syndrome (AIDS). Clinical, virological, and immunological data are obtained from six clinical centers and six central laboratories using a variety of hardware components and software packages. Data are merged and processed on a mainframe computer at the Biostatistics Office at the University of Southern California. The advantages and disadvantages of this system are discussed relative to the dynamics of the study, the magnitude and nature of the database, and the organization of the distributed centers involved.     

Chaos-based selective encryption for H.264/AVC

Encryption techniques are usually employed to maintain the secrecy of the video streams transmitted via a public network. However, full encryption using strong cryptographic algorithms is usually not necessary if the purpose is to destroy the commercial value by preventing pleasant viewing. For this purpose, selective encryption is preferred as its operating efficiency is higher. Here, a chaos-based selective encryption scheme implemented on the H.264/AVC standard is proposed. The scheme employs multiple Rényi chaotic maps to generate a pseudorandom bit sequence which is used to mask the selected H.264/AVC syntax elements. It provides sufficient protection against full reconstruction while keeping the format compliance property so as not to cause decoding error without the key. The operating efficiency is high due to the low computational complexity of the Rényi chaotic map, as justified by the simulation results using video clips at various resolutions. Moreover, the security analyses show that the proposed algorithm is highly sensitive to the secret key and possesses good perceptual security.     

可视化约束程序编程环境的设计与实现

该文提出了一种应用于多数化CAD系统的面向约束的程序设计思想,开发了一个实用的可视化约束程序编程环境。不仅简化了用户在参数化图形设计过程中大量约束程序的编程,而且提出了一种应用于参数化CAD系统设计图形约束程序的可视化方法。     

地震信号时——频特性与瞬时动态范围

本文利用小波变换的方法，分析了地震信号的时一频特征，由时一频特征曲线可以看出，随着时间的增加，地震信号高频分量相对于低频分量之比越来越小。在此基础上给出了地震信号瞬时动态范围的定义和物理解释，进而指出，在地震采集仪器中，为了获得深层的高频信号，必须采用动态范围高达２４位的新型过采样Σ－△Ａ／Ｄ转换器。     

Anti-glomerular basement membrane and anti-neutrophil cytoplasm antibody-positive vasculitis presenting with peripheral neuropathy and acute renal failure

We report a case of Epstein-Barr (EB) infection that presented as an acute monoarthritis of the knee. This formed a Baker's cyst which ruptured into the gastrocnemius. The peripheral and synovial white blood counts were dominated by neutrophils. After repeated aspirations, spontaneous resolution occurred.