车载自组网中一种支持群签名认证的分布式密钥管理方案

群签名具备良好的匿名认证特性,满足车载自组网信息安全和隐私保护需求。但是,其作废开销较大,不适于在大规模网络环境中应用。为此,本文提出了一种支持群签名认证的分布式密钥管理方案DKM,将车载自组网的覆盖区域划分为若干子区域,车辆周期性地从所在子区域的群管理机构更新群密钥。这样,作废某个成员只需要在其拥有合法密钥的子区域内通告,而不是整个网络,有利于降低作废开销。同时,DKM中的密钥更新机制能够保证车辆的群密钥的私密性,从而避免了车辆与区域群管理机构的授权争议,保持了数字签名的不可否认性。性能分析表明DKM能够显著缩短作废列表长度,同时没有增加认证开销。     

面向工业平稳/非平稳复杂系统的在线故障监测技术

针对复杂系统中关键性能指标（KPI）相关故障检测方法检测精度低的问题,提出基于双层改进潜结构投影（DL-IPLS）的KPI相关故障检测方法. 利用协整分析和主元分析建立底层模型,对非平稳和平稳变量进行特征提取. 将提取的信息进行融合,建立改进潜结构投影的上层模型,根据融合信息对KPI的贡献进行空间分解. 在2个正交子空间中设计统计量,实现KPI相关故障的在线监测. 田纳西-伊斯曼过程和青霉素发酵过程的仿真结果表明,在面向工业平稳和非平稳复杂工业系统检测时,所提方法有效提高了KPI相关故障的检测率,降低了KPI无关故障的误报率.     

人民币汇率机制改革中参考一篮子货币的思考

分析了人民币汇率机制改革中选择“参考一篮子货币”制的原因;在肯定这次汇率制度改革给我国带来的有利影响,同时指出了参考一篮子货币制在短期内将面临的问题,并进一步提出关于完善该汇率制度的相关措施和建议,以期对我国汇率制度改革提供参考。     

大型非周期相控阵天线协同设计

针对大型非周期相控阵天线的特点,提出一种多学科、多领域协同设计的方法。然后运用该方法指导两个产品天线设计,围绕协同设计的典型流程和几个关键控制点展开论述。在测试阶段实测天线的主要指标,天线1辐射端面平面度≤1.4 mm,栅瓣电平≤-20 dB,天线2辐射端面平面度≤1.1 mm,栅瓣电平≤-18 dB,实测数据与仿真结果吻合,各项指标优于设计输入要求,使用性能良好,验证协同设计方法的有效性。最后指明大型非周期相控阵天线协同设计的进一步研究方向。     

Facile Fabrication of Poly(vinyl alcohol)/Polyquaternium-10 (PVA/PQ-10) Anion Exchange Membrane with Semi-Interpenetrating Network

Anion exchange membranes (AEMs) are one of the core components of AEM fuel cells. A series of poly(vinyl alcohol)/polyquaternium-10 (PVA/PQ-10) AEMs with semi-interpenetrating networks (s-IPNs) are prepared by a simple solution-casting method using glutaraldehyde (GA) as a cross-linking agent. Subsequently, the prepared PVA/PQ-10 cross-linked membranes are characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, mechanical analysis, water uptake and swelling ratio tests, ion exchange capacity (IEC) tests, ionic conductivity measurements, and oxidative/alkaline stability tests. The effects of the mass ratio of PVA and PQ-10 and the amount of cross-linking agent GA on the performance of the PVA/PQ-10 cross-linked membranes are systematically explored. The results show that the cross-linked PVA/PQ-10 AEMs have high IEC and low water uptake and swelling ratio, and its maximum ionic conductivity can reach 79.37 mS cm^–1 at 80 °C. In addition, the PVA/PQ-10 cross-linked membrane has good oxidative and alkaline stability under optimal preparation conditions. These results may provide valuable insights toward more effective scheme designs and new, simple preparation methods for AEMs with s-IPN structures.     

Investigation of the Anti-Methicillin-Resistant Staphylococcus aureus Activity of (+)-Tanikolide- and (+)-Malyngolide-Based Analogues Prepared by Asymmetric Synthesis

Herein, we report antibacterial and antifungal evaluation of a series of previously prepared (+)-tanikolide analogues. One analogue, (4S,6S)-4-methyltanikolide, displayed promising anti-methicillin-resistant Staphylococcus aureus activity with a MIC of 12.5 µg/mL. Based on the antimicrobial properties of the structurally related (−)-malyngolide, two further analogues (4S,6S)-4-methylmalyngolide and (4R,6S)-4-methylmalyngolide bearing a shortened n-nonyl alkyl side chain were prepared in the present study using a ZrCl₄-catalysed deprotection/cyclisation as the key step in their asymmetric synthesis. When these were tested for activity against anti-methicillin-resistant Staphylococcus aureus, the MIC increased to 50 µg/mL.     

工业控制中实时数据传递新技术

采用面向对象机制，论述了Ｗｉｎｄｏｗｓ环境下动态数据传递的基本原理，介绍了主要动态数据交换事务以及在工业控制中动态数据传递的流程。并采用ＢｏｒｌａｎｄＣ＋＋语言给出了工业控制中动态数据传递的基本实现     

An experimental evaluation of the effects of ripple current generated by the power conditioning stage on a proton exchange membrane fuel cell stack

In this article, an impedance model of the proton exchange membrane fuel cell stack (PEMFCS) is proposed. The proposed study employs an equivalent circuit of the PEMFCS derived by the frequency response analysis technique. An equivalent circuit for the PEMFCS is developed to evaluate the effects of ripple currents generated by the power-conditioning unit. The calculated results are then verified by means of experiments using a commercially available PEMFCS. The relationship between ripple current and fuel cell performance, such as power loss and fuel consumption, is investigated. Experimental results show that the ripple current can contribute up to a 6% reduction in the available output power. This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National Laboratory, and T. Dubois, U.S. Army CECOM.     

木瓜凝乳蛋白酶的分离纯化及性质研究

目的　建立简单有效的木瓜凝乳蛋白酶分离纯化方法 ,并研究其酶学性质。方法　采用离子交换层析直接将木瓜凝乳蛋白酶分离纯化 ,通过温度、葡萄糖、盐酸胍及其他因素研究酶学性质。结果　木瓜凝乳蛋白酶有较高的热稳定性 ,盐酸胍对其有抑制作用 ,葡萄糖对其有激活作用。结论　离子交换层析是简单有效的分离纯化木瓜凝乳蛋白酶的方法 ,木瓜凝乳蛋白酶值得进一步开发利用。     

The role of isotopic techniques on the evaluation of the agronomic effectiveness of P fertilizers

Many isotopic techniques can be applied to determine the relative immediate and residual effectiveness of P fertilizers. Using isotopes as tracers, the percentage of utilization by plants of the P derived from a fertilizer can be determined. However this is only possible during the three or four months after the application. Therefore, the P fertilizers may be classified only according to their relative immediate effectiveness. To also evaluate residual effect, which can be observed when more P is applied than is removed with harvest, isotopes of phosphorus can be used. This residual effect is determined by comparing pool sizes of bioavailable soil P in soils with and without P fertilizer aged in soil. The bioavailable soil P pool may be analyzed according to three isotopic experimental procedures which give access to either the A value, or the E value or the L value. The aims, the similarities and the differences between these three procedures, are examined. Some of the theoretical and practical constraints of each method are described in this paper; they must be followed in order to obtain reliable information for agronomic purposes. A method involves measuring the rate of isotopic exchange of phosphate ions in soil-solution systems maintained in steady-state. It is now possible to predict the effectiveness of P fertilizers, whatever their chemical form when this method is applied on soil samples where P fertilizers were applied.This paper was originally submitted as part of the special issue on Evaluation of the Agronomic Effectiveness of Phosphate Fertilizers through the use of Nuclear Related Techniques edited by F. Zapata