Pitting corrosion resistance of La added 316L stainless steel in simulated body fluids

Lanthanum (La), a rare earth element with anticoagulative and antiphlogistic function, was added into the medical grade 316L stainless steel in order to improve its biocompatibility. The corrosion resistance of the La added 316L steel in two different simulated body fluids, simulated blood plasma and Hank's solution, was evaluated. The result showed that the addition of La in the steel could largely affect the corrosion behavior of the steel. The steel with 0.01% La showed the widest passive region and the best resistance to pitting attack, within the addition range of La from 0.01% to 0.08%. The corrosion resistance improvement of La added 316L stainless steel is probably due to the effect of La on the purification of the steel, the modification of inclusions, and the passive film formation in the simulated body fluids.     

Sulfur distribution in coke and sulfur removal during pyrolysis

In order to investigate the mechanisms of coke desulfurization by blowing additional gas into coking chamber during pyrolysis process, some experiments were conducted to study the effects of some factors on the distribution of sulfur in coke. These factors include pyrolysis temperatures, the kinds of the blowing gases and the diameters of coking chamber. It was found that sulfur was mainly released at the range of 300–600 °C. Under this temperature range, the sulfur content in coke can be reduced by 0.05–0.06% by blowing N₂, CO or CH₄, and by 0.14% by blowing H₂ at a space velocity of 1.2 mm/s compared with the absolute sulfur content of 0.92% in the case without gas feeding. Obviously, H₂ is more effective on sulfur removal than N₂, CO or CH₄. The total, organic and inorganic sulfur contents in coke increase with increasing the diameter of coking chamber under identical pyrolysis conditions. Both organic and inorganic sulfur contents in coke increase regularly from the center to brim at identical height of a coke column for all the cases. In addition, the organic and inorganic sulfur contents at the cranny surface are higher than those in interior at the same sampling position. X-ray photoelectron spectroscopy (XPS) analyses suggest that the main contributions to the increase of inorganic and organic sulfur contents are due to the formation of negative bivalent sulfur and thiophenic compounds, respectively.     

Effect of Magnetic Interaction on Thermally Activated Reversal in a Magnet With a Distribution of Energy Barriers

The time dependence of magnetization is usually expressed as M(t)=M₀-SInt [see Proc. Phys. Soc. 62, 562 (1949)] for magnetic viscosity experiments. Considering magnetic interaction during the thermal activation process, a form as M(t)=M₀-SIn(t+t₀) is deduced. The dipolar interaction and exchange coupling in a magnet can lead to positive and nonpositive t₀, respectively. In the experiments of the magnetic viscosity for nanocrystalline Pr₂Fe₁₄B ribbons, the existence of positive t₀ is confirmed.     

一种用户行为分析的动态备份机制

目前大多数分布式存储系统采用静态备份机制保证系统的高可靠性,灵活性差,不适合系统规模及用户访问量不断变化的存储系统．因此提出一种基于用户行为分析的动态备份机制,通过分析用户行为获得相关信息来动态改变备份数量及确定备份位置,具有较强的灵活性,适合大规模的分布式存储系统;实现动态备份系统将其应用于已建立的科技信息数据中心．通过实验分析表明,该动态备份机制能提高系统的可靠性。     

全链路成像光谱仪信噪比仿真

研究成像光谱仪优化问题,由于光谱成像受到环境噪声影响,传感器精度达不到要求,传统信噪比优化仿真方法,通常只考虑传感器本身的特性,没有综合考虑地物的光谱特性、辐射传输对其影响,导致传感器信噪比很难满足要求。为消除噪声提出了全链路成像光谱仪信噪比仿真方法,以叶面积指数反演应用为背景,从地面植被反射率信号出发,考虑大气辐射传输和传感器能量转换过程,建立了全链路成像光谱仪信噪比仿真模型,并通过具体实例进行验证和分析。理论分析和仿真结果表明:方法是对成像光谱仪信噪比仿真的一种全新而有益的尝试,具有很好的扩展性,传感器的研制设计提高性能指标,并缩短研制周期,为设计提供了参考。     

基于Web services的WebGISVisA体系结构研究与实现*

针对目前网络地理信息系统体系结构难以实现Internet环境下的异构空间信息的互操作问题,深入分析其主要原因,在对现有网络地理信息系统的三层体系结构进行深入分析的基础上,提出一种基于Web services的网络地理信息系统体系结构(Web-based geographical information services visualization architecture,WebGISVisA).WebGISVisA体系结构通过Web services对各个地理信息系统组件进行包装,实现各个组件的跨平台操作,从技术上使得客户端和服务端达到了负载平衡,完成了WebGIS三维的虚拟现实,实现了在Internet下空间数据互操作和跨平台的功能,最大限度地达到数据共享.     

Global software testing under deadline pressure: Vendor-side experiences

ContextIn the era of globally-distributed software engineering, the practice of global software testing (GST) has witnessed increasing adoption. Although there have been ethnographic studies of the development aspects of global software engineering, there have been fewer studies of GST, which, to succeed, can require dealing with unique challenges.ObjectiveTo address this limitation of existing studies, we conducted, and in this paper, report the findings of, a study of a vendor organization involved in one kind of GST practice: outsourced, offshored software testing.MethodWe conducted an ethnographically-informed study of three vendor-side testing teams over a period of 2 months. We used methods, such as interviews and participant observations, to collect the data and the thematic-analysis approach to analyze the data.FindingsOur findings describe how the participant test engineers perceive software testing and deadline pressures, the challenges that they encounter, and the strategies that they use for coping with the challenges. The findings reveal several interesting insights. First, motivation and appreciation play an important role for our participants in ensuring that high-quality testing is performed. Second, intermediate onshore teams increase the degree of pressure experienced by the participant test engineers. Third, vendor team participants perceive productivity differently from their client teams, which results in unproductive-productivity experiences. Lastly, participants encounter quality-dilemma situations for various reasons.ConclusionThe study findings suggest the need for (1) appreciating test engineers’ efforts, (2) investigating the team structure’s influence on pressure and the GST practice, (3) understanding culture’s influence on other aspects of GST, and (4) identifying and addressing quality-dilemma situations.     

基于运动相关皮层电位握力运动模式识别研究

面向基于脑-机接口（Brain-computer interface,BCI）的脑-机交互控制（Brain-machine interaction control,BMIC）——直接脑控机器人,提出一种新的左、右手握力运动参数范式,在该范式下探索左、右手握力运动相关皮层电位/运动相关电位（Movement-related potentials,MRPs）的时域特征表示并识别握力运动模式.在涉及左、右手4个不同任务的实验中采集了11个健康被试的脑电信号,任务期间要求被试以2种握力变化模式之一完成自愿握力运动,每种任务随机重复30次.不同握力任务之间具有显著差异的运动相关电位特征用于识别握力运动模式.分别用基于核的Fisher线性判别分析和支持向量机识别4个不同的握力运动任务.研究结果进一步证实运动相关电位可以表征握力运动规划、运动执行和运动监控的脑神经机制过程.基于核的Fisher线性判别分析和支持向量机分别获得24±4%和21±5%的平均错误分类率.最小误分类率是12%,所有被试平均最小误分类率为20.9±5%.与传统的仅仅识别参与运动的肢体类型以及识别单侧肢体运动参数的研究相比,本研究可望为脑-机交互控制/脑控机器人接口提供更多的力控制意图指令,奠定了后续的对比研究基础.