Hydrophilization of gigaporous polystyrene microspheres with saccharide as high-speed protein chromatography base support

Gigaporous poly(styrene–divinylbenzene) (PS) microspheres were hydrophilically modified with natural saccharide to minimize their nonspecific adsorption to proteins. The microspheres were chloroacetylated through Friedel–Crafts acetylation with chloroacetyl chloride, and then coupled with diacetone-D-glucose (DAGlu) through the Williamson reaction, and the protecting groups were removed on DAGlu. Results showed that the PS microspheres were successfully coupled with DAGlu and that the gigaporous structure was well maintained. After hydrophilization (Glu-PS), nonspecific adsorption of proteins on PS microspheres was greatly reduced. The high surface density of hydroxyl groups on Glu-PS microspheres surface make it easy to derivatize the spheres by classical methods. Flow experiments showed that the Glu-PS column had low backpressure, good permeability, and mechanical stability. All results indicate that the Glu-PS microspheres have great potential applications in high-speed protein chromatography.     

低硅含镁球团矿抗压强度及冶金性能

提高入炉原料品位降低硅含量,改善冶金性能是高炉精料的主要方向。研究了低硅球团矿的还原膨胀率及MgO对低硅球团矿抗压强度和冶金性能的影响。研究结果显示,低硅球团矿虽然具有品位高,脉石含量低等优点,但随着SiO2含量的降低球团矿还原膨胀率恶化,影响高炉冶炼。低硅球团配加含镁添加剂可以有效控制还原膨胀率,同时改善球团矿的还原度和熔滴性能。球团矿SiO2的质量分数低于2%时,还原膨胀率在60%以上;当MgO的质量分数提高到2.15%以上时,还原膨胀率能降到20%以下,但随着MgO含量的增加低硅球团矿抗压强度下降,需要提高焙烧温度,才能形成稳定的铁酸镁,改善抗压强度。MgO的质量分数为2.15%时,焙烧温度要提高到1 270℃,MgO的质量分数超过2.8%以上时,焙烧温度需要提高到1 300℃。     

A Parallel Platform for Web Text Mining

With user-generated content, anyone can De a content creator. This phenomenon has infinitely increased the amount of information circulated online, and it is beeoming harder to efficiently obtain required information. In this paper, we describe how natural language processing and text mining can be parallelized using Hadoop and Message Passing Interface. We propose a parallel web text mining platform that processes massive amounts data quickly and efficiently. Our web knowledge service platform is designed to collect information about the IT and telecommunications industries from the web and process this in-formation using natural language processing and data-mining techniques.     

2021 年 4 期目录

为了提高涠西工区大断裂及小断层成像效果,通过在涠西工区应用叠前逆时偏移技术（RTM）多轮次的测试分析及试处理,找到了影响海上复杂构造的RTM成像效果的关键问题,针对性开展了单边放炮观测孔径定义方式、宽屏RTM算法（低频保护的Laplace算法优化）和RTM照明补偿等技术方法优化,并开发了相应的RTM模块。测试应用结果形成了一套RTM技术在涠西区块精细成像的技术参数。RTM成像处理效果在研究过程中逐步大幅提高,大断层成像、断点的归位比以往成果及此次叠前深度偏移更加清晰、准确,构造成像可信度提高,基底构造连续清晰,尤其在陡倾角地层及小断层成像效果较好。     

Formation mechanism of basin-like depression defect in electric upsetting process of Ni80A superalloy

A kind of surface instability, basin-like depression defect companied by mixed grain structure at the bottom of large-scale valve during electric upsetting process, would significantly influence the microstructures and mechanical properties of components. In order to analyze the forming process of the basin-like depression defect, a finite element model for the electric upsetting process of Ni80A superalloy was developed using multi-field and multi-scale coupling analysis method. Subsequently, a series of parameters loading path schemes for force and current were designed by varying the initial value, peak value and value level, and their effects on basin-like depression and mixed grain structure were simulated and uncovered. It is concluded that the changes of heating speed and pressurization speed result in the different flow velocities between the inner and outer layers of billet, thus exerting the basin-like depression. Simulation results also indicate that these defects can be optimized through the parameter coordination between force and current. Finally, the validity and reliability of the finite element model were verified by physical experiments in electric upsetting process.     

Behavior of hydrogen in an Ni3Al compound investigated by means of hydrogen microprint technique

Hydrogen microprint technique, which can visualize microscopic location in the surface where hydrogen atom has been evolved, was applied to an isothermally forged Ni-rich Ni₃Al compound to investigate the behavior of hydrogen, and comparison was made with cold-rolled pure nickel. Hydrogen evolution behavior was examined when one side of the specimen was charged with hydrogen gas of 0.2 MPa and/or the specimen was deformed plastically in tension. Hydrogen in nickel aluminide was concluded to be trapped by dislocations and to move with gliding dislocations, as well as the hydrogen in other metals and alloys. It was presumed that molecular hydrogen which exists in the environment decomposes at the surface, invades and permeate the interior in nickel aluminide. Hydrogen in nickel was also found to be transported with gliding dislocations.     

Integrating security activities into the software development life cycle and the software quality assurance process

Security concerns should be an integral part of the entire planning, development, and operation of a computer application. Inadequacies in the design and operation of computer applications are very frequent source of security vulnerabilities associated with computers. In most cases, the effort to improve security should concentrate on the application software. The system development life cycle (SDLC) technique provides the structure to assure that security safeguards are planned, designed, developed and tested in a manner that is consistent with the sensitivity of the data and/or the application. The software quality assurance process provides the reviews and audits to assure that the activities accomplished during the SDLC produce operationally effective safeguards.This paper addresses two issues of concern to those responsible for ensuring that the safeguards incorporated into application software are adequate and appropriate. The first issue addresses the integration of specific security activities into the SDLC. The discussion of this issue addresses the following security activities in the SDLC; determination of the sensitivity of the application and data; determination of security objectives; assessment of the security risks; conduct of the security feasibility study; definition of security requirements; development of the security test plan; design of the security specifications; development of the security test procedures; writing of the security-relevant code; writing of the security-relevant documentation; conduct of the security test and evaluation; writing on the security test analysis report; and, preparation of the security certification report.The second security issue addresses the security reviews and audits that should be integrated into the software quality assurance process to ensure that the security activities in the SDLC are accomplished. The security reviews and audits discussed include: the security requirements review; the security design review; the security specifications review; the security test readiness review; and the security test and evaluation review. Also addressed is how quality software is defined and achieved and why and how the concept of quality should be applied to application software security safeguards.     

电力系统谐波和间谐波检测方法综述

电力系统谐波和间谐波的实时精确检测是谐波评估和治理的前提和基础。结合国内外谐波检测技术的发展现状,从检测信号模型出发,对基于加窗、加窗插值、谱估计和希尔伯特—黄变换(HHT)的谐波检测算法进行了分类和总结,指出了各种算法在谐波检测中的优缺点。最后,对电力系统谐波检测中需要关注的问题和研究方向进行了探讨。     

基于有限相量测量单元测量故障分量信息的故障定位算法

提出了一种基于有限同步相量测量单元(PMU)测量故障分量信息的故障定位算法.采用间隔母线配置PMU的布点策略,即在2条配置有PMU的母线之间间隔一条非零注入并且未配置PMU的母线.该算法首先运用叠加原理获得系统的纯故障等值模型,进而对纯故障等值模型进行等价变换,以获得故障线路两端的系统阻抗等值模型和故障点注入电流源的转移等值模型,最后结合这2种等值模型,实现对故障点的精确定位.该算法没有迭代过程,不存在伪根问题,且计算量小.此外,该算法不受电网拓扑、过渡电阻、振荡状态及系统运行方式的影响.动模试验结果验证了该方法的有效性.