Influence of growth rate on the structural and morphological properties of TiN, ZrN and TiN/ZrN multilayers

The effect of the deposition rate on the structural and morphological properties of TiN and ZrN single layers and TiN/ZrN multilayers deposited by radiofrequency reactive magnetron sputtering has been studied. The total pressure was kept constant and the growth rate variation was obtained by small difference of nitrogen concentration in the fed gas. The decreasing deposition rate results in a structural change in the thin films from (111) orientation to (100) one. As consequence the surface morphology becomes smoother. Films roughness is strongly related with texture and it decreases with an increase in the (100) X-ray diffraction line intensity. In order to achieve a clear interpretation of our experimental results, the ratio between the N⁺ ions of the plasma and the atoms number reaching the substrate was considered. At high deposition rate with respect to the N⁺ concentration, the chemical potential of transition metal on (100) growth surface is higher than (111) one favouring the (111) orientation of the films. On the contrary, when the growth rate is low with respect to the nitrogen concentration, the chemical potential of transition metal on (111) growth surface is higher than the (100) one leading to a preferential growth in the (100) direction.     

Controlling the Critical Temperature in Mg1−x Al x B2

Here we report synthesis and characterization of high quality samples of the superconducting system Mg_1−x Al _x B₂, with a novel optimized preparation method, in a wide range of Al concentration. All the physical properties of the samples can be tuned continuously with increasing Al content. We have characterized the samples for their structural, morphological and magnetic properties with high resolution XRD, SEM-EDS and susceptibility measurements. We have prepared a large number of Al doped MgB₂ in the range 0<x<0.57. All the samples are bulk superconductors and the critical temperature show a smooth and regular behavior as a function of x. This work was supported by European project 517039 “Controlling Mesoscopic Phase Separation” (COMEPHS) (2005). An erratum to this article can be found at     

Systems that Should Have Failed: Critical Infrastructure Protection in an Institutionally Fragmented Environment

Recent years have witnessed major governmental initiatives regarding critical infrastructure protection (CIP). During that same time, critical infrastructures (CIs) have undergone massive institutional restructuring under the headings of privatization, deregulation and liberalization. Little research has gone into understanding the interactions between these two developments. In this article, we outline the consequences of institutional restructuring for the changing ways in which CIs ensure the reliability and security of their networks and services. Neither Normal Accident Theory nor High‐Reliability Theory can account for reliability under these conditions. We then investigate the implications of these findings for CIP.     

可实现性k-ε模型在水轮机流场计算中的应用

本文针对目前水轮机转轮内部流场计算中存在的偏工况计算困难的问题，探讨了一种不同于标准k-ε模型的可实现性k-ε模型（Realizablek-ε在水轮机偏工况计算中的应用。文章首先对该模型的优点进行了分析。然后针对某混流式转轮进行了计算，计算与实验结果比较表明，二者在设计工况附近时十分接近；在小开底小流量下，对转轮的主要特征的预测也是成功的。但小开度下计算值与实测值之间的差别也表明，在水轮机偏工况计算中，该湍流模型有待进一步改进。     

框架结构焦仓的定向倒塌爆破

介绍了框架结构焦仓定向爆破拆除的设计与施工，着重介绍了爆破参烽的选取及安全防护措施。达到预期的爆破效果。     

Synchronization of quadrature-quadrature phase-shift keying signals

The key synchronization aspects in the system design of a QQPSK (quadrature-quadrature phase-shift-keying) modem are addressed. The sensitivity of the data demodulator to synchronization errors is discussed, and contextually the performances of some IF and baseband carrier phase and symbol timing recovery schemes are evaluated both theoretically and by computer simulations. In particular, a fourth-power IF carrier/clock regenerator and two baseband clock recovery schemes, with and without the aid of data decisions, respectively, are taken into account. The analysis shows on the one hand the substantial robustness of QQPSK to carrier phase errors and the adequacy of the examined carrier extraction scheme. On the other hand, the remarkable sensitivity of QQPSK to symbol timing inaccuracy is stressed and the need to resort to the newly proposed decision-aided baseband clock recovery scheme is pointed out     

纳米β-Ni(OH)2与球型Ni(OH)2的热性能比较研究

用配位沉淀法合成出纳米级Ni（OH）2，并对其进行XRD，TEM，DSC分析，分析结果表明，所得纳米β-Ni（OH）2为可用作电极材料的β-Ni（OH）2，粒径为30－40nm，且热分解温度比普通球镍低10℃左右，摩尔分解热比普通球镍低4－7kJ，从理论上分析了产生此现象的原因。     

Carbon mineralization from composts and food industry wastes added to soil

We have studied the short term C mineralization of six wastes from important food industries, one sludge from a biogas plant and three composts. All the wastes were characterized chemically and fractionated according to the Van Soest method. The fresh wastes were incubated under controlled environment conditions to determine the C mineralization rate. Based on first order mineralization kinetics, we calculated the hypothetical amount of stable C in the wastes as the amount of C that would not be mineralized within one year under field conditions. The percentage of stable organic C in the organic matter was in general much larger in the composts than in the other wastes, but when expressed on dry matter, the non-composted wastes had comparable or larger amounts of stable organic C than the composts and have a considerable potential for supplying organic matter to soils, and hence for C sequestration. The amount of stable organic C could best be predicted by the total N content of the wastes (R _a ² = 0.855), whereas the results of the fractionation had very little predictive power, probably due to problems related to the high ash content of some of the wastes. An index that combined stable organic C and N and P content in the wastes was calculated to assess possible limitations for applying these wastes in agriculture. Under current nutrient legislation in Western Europe, a number of these wastes will only be usable in small amounts, but these and other food industry wastes could still prove to be valuable soil amendments in nutrient poor situations, for increasing soil organic C content and supplying nutrients.