Study of intermetallic crystal growth between Nb and molten 52In-48Sn solder

The reactions between Nb and molten, eutectic In-Sn solder have been studied in the temperature range 130–240°C and for times ranging up to 12 months. Hexagonal platelet crystals of NbSn₂ form an intermetallic compound (IMC) layer that provides adhesion between solder and substate, but which grows extremely slowly even at 200°C. A model explaining the observed IMC growth kinetics is developed and relevant activation energies and model parameters are calculated. Applications include high-temperature electronics interconnection, where the device is secured to the substrate via an adhesive component and the solder is designed to melt, preventing fatigue failure by temperture cycling.     

用可编程DSP实现IEEE 802.16 PHY信号处理

IEEE802.16标准的各个版本都规定了PHY(物理层)的多种选项,包括调制、信道编码和天线分集技术。物理信道带宽可以在1.25MHz～20MHz之间变化。上述所有选项都会影响基站的性能和信号处理复杂度。许多客户希望提供一种可以从802.16-2004升级到802.16e标准的方法。上述需求以及对支持互通性(成功部署新标准的关键)的需求,都要求基站的PHY采用可编程的信号处理器件。图1为802.16基站基带信号链路基本框图。因为802.16-2004和802.16e标准都是在OFDM基础上建立的,所以FFT和IFFT起了很大的作用。这两种变换都用于频域副载波(携带编码的数…     

Elastic properties and electronic structure of vanadium silicides-a density functional investigation

Vanadium and silicon form several binary compounds; the most well characterized structures have the compositions V:Si = 3:1, 5:3, 6:5, 1:2. Spin-polarized density functional band-structure calculations using the projector augmented wave method have been carried out for the stable binary compounds in the Si–V system. As many rare earth and early transition metals are refractory materials, the study focuses on the ground state structures and their stabilities by determining their elastic properties. The magnetic properties are also investigated because structurally related Si–Mn compounds exhibit magnetism. All the silicides investigated were found to be refractory, hard, metallic materials and no magnetism was found in the ground state structures.     

Contextual influences on technology use mediation: a comparative analysis of electronic medical record systems

Developing, implementing and assimilating information technologies into organizational practices pose significant technical and social challenges. In this paper, we explore technology use mediation (TUM) processes in two cases of electronic medical record system use in two healthcare organizations. In our analysis, we examine contextual influences on mediation and consider TUM processes and outcomes in projects utilizing modern systems development methods. We found that crucial TUM actions occurred during systems development phases as well as during system use, that mediation was vitally important with these specialized IT artefacts, and that system configuration required changes to software infrastructure and code. Organizational size influenced the availability and the effectiveness of mediation resources; with adequate resources committed to the task, the institutional environment presented substantial, but not insurmountable, challenges to technology use mediation. We consider implications for practice and suggest future research directions.     

Advantages of the hollow (concave) turbine for multi-phase agitation under intense operating conditions

The mixing literature on hollow blade turbines (HBTS), for operation in fully turbulent flow, is reviewed and compared with the results of our own studies. The SCABA 6SRGT is shown to have an almost identical pumping rate to a disc turbine, when compared at the same diameter and specific power. An equation is proposed for the effect of scale and blade geometry on the power number of a range of concave hollow blade agitators. The “flooding-loading” condition is revisited. It is found that, when compared at conditions above the minimum Froude number required to disperse gas, the HBT designs are as energetically efficient as Rushton turbines for dispersing gas. If we compare them on an “ungassed” power basis, as is the usual literature case, then the HBT is more efficient because of their ability to disperse gas without significant loss of power. The much lower power number resulting from the streamlined blade design of the HBTs also ensures that they achieve the minimum Froude number required to disperse gas at a much lower power than a RT. A simple method to avoid “flooding” for radial turbines, based on this work, is proposed. Under fully loaded conditions the hollow blade turbines will handle high gas rates without significant loss of power and this ability is a function of the degree of streamlining. For the suspension of high levels of solids the D=T/2 hollow blade turbines, at a clearance of T/4, are found to be amongst the most efficient agitators especially under gassed conditions, where almost no effect of gassing on the just suspension speeds were noted.     

Displaced aggression is alive and well: A meta-analytic review.

Content analysis of 122 social psychology textbooks confirmed that displaced aggression received a surge of attention immediately following J. Dollard, L. W. Doob, N. E. Miller, O. H. Mowrer, and R. R. Sears (1939), but subsequent interest sharply declined. Contemporary texts give it little attention. By contrast, meta-analysis of the experimental literature confirms that it is a robust effect (mean effect size/&=/&+0.54). Additionally, moderator analyses showed that: (a) The more negative the setting in which the participant and target interacted, the greater the magnitude of displaced aggression; (b) in accord with N. E. Miller's (1948) stimulus generalization principle, the more similar the provocateur and target, the more displaced aggression; and (c) consistent with the contrast effect (L. Berkowitz & D. A. Knurek, 1969), the intensity of initial provocation is inversely related to the magnitude of displaced aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feeding trial of instant food containing lyophilised yam powder in hypertensive subjects

BACKGROUND: It was reported in a previous paper that the yam tuber storage protein dioscorin exhibited antihypertensive effects on spontaneously hypertensive rats. The aim of the present study was to evaluate and compare the effects of packets of instant food (30 g) with (treated meal) and without (placebo) lyophilised yam powder on hypertensive subjects. RESULTS: A placebo‐controlled feeding trial was conducted daily for 5 weeks (stage 1), followed by a 1 week washout and then a 5 week crossover (stage 2). Twenty‐one subjects finished the trial. One packet of treated meal contained 140 ± 2.54 mg of dioscorin according to enzyme‐linked immunosorbent assay. The blood pressure results of the treated meal and placebo groups at stage 1 end versus originals, but not at stage 2 end versus stage 2 beginning, were significantly different by the paired t test. Systolic (SBP) and diastolic (DBP) blood pressure readings after treated meal intervention, but not after placebo intervention, differed significantly from the original values based on one‐way analysis of variance followed by the post hoc Tukey test; the reductions in SBP and DBP were 6.52 and 4.76 mmHg respectively. The feeding trial did not appear to affect serum lipid profiles or other biochemical measurements of cardiovascular risk. CONCLUSION: Intake of an instant food containing 140 mg of dioscorin over 5 weeks had a regulating effect on human blood pressure. Copyright © 2008 Society of Chemical Industry     

The process of enterprise resource planning implementation and business process re-engineering: tales from two Chinese small and medium-sized enterprises

Abstract.  Using an innovative process model, we describe and analyse the process of introducing enterprise resource planning (ERP) systems in two Chinese small and medium-sized enterprises and especially their decisions concerning business process re-engineering. First we compared the results from our cases with Martinsons' earlier work (2004). One case seemed to fit most of the characteristics of a private venture (PV) whereas the other case, also a PV, had a very low degree of fit. We used the process model to offer further insights and features such as its predictive power. Second, and as predicted, we also observed the differential role of top management support in the two Chinese companies. But thirdly, and somewhat surprisingly, we found that cultural issues were only of limited importance. Finally, the ability of the project team to deal with unexpected events was seen as critical in ensuring the stability of a project. In contrast, project drift is shown to lead to a degree of chaos. We offer some suggestions as to how stakeholders can improve their chances of implementing ERP systems more successfully.