海湾战争后防空系统及雷达电子设备的新发展

本文针对海湾战争后的新形势,介绍了战略防御的新构想、战术防空导弹系统及21世纪的防空概念,论述了AEW、AWACS、战场监视目标攻击雷达及其它雷达的最新发展情况,此外,还对国外的反隐身技术进展情况作了介绍。     

A single mutation Asp229 --> Ser confers upon Gs alpha the ability to interact with regulators of G protein signaling

RGS proteins (regulators of G protein signaling) are GTPase activating proteins (GAPs) for Gi and Gq families of heterotrimeric G proteins but have not been found to interact with Gs alpha. The Gs alpha residue Asp229 has been suggested to be responsible for the inability of RGS proteins to interact with Gs alpha [Natochin, M., and Artemyev, N. O. (1998) J. Biol. Chem. 273, 4300-4303]. To test this hypothesis, we have investigated the possibility of generating an interaction between Gs alpha and RGS proteins by substituting Gs alpha Asp229 with Ser and replacing the potential Gs alpha Asp229 contact residues in RGS16, Glu129 and Asn131, by Ala and Ser, respectively. RGS16 and its mutants failed to interact with Gs alpha. A single mutation of Gs alpha, Asp229Ser, rendered the Gs alpha subunit with the ability to interact with RGS16 and RGS4. Like RGS protein binding to Gi and Gq alpha-subunits, RGS16 preferentially recognized the AlF4--bound conformation of Gs alpha Asp229Ser. In a single-turnover assay, RGS16 maximally stimulated GTPase activity of Gs alpha Asp229Ser by approximately 5-fold with an EC50 value of 7.5 microM. Our findings demonstrate that Asp229 of Gs alpha represents a major barrier for Gs alpha interaction with known RGS proteins.     

Schedulability Analysis of Global Scheduling Algorithms on Multiprocessor Platforms

This paper addresses the schedulability problem of periodic and sporadic real-time task sets with constrained deadlines preemptively scheduled on a multiprocessor platform composed by identical processors. We assume that a global work-conserving scheduler is used and migration from one processor to another is allowed during a task lifetime. First, a general method to derive schedulability conditions for multiprocessor real-time systems will be presented. The analysis will be applied to two typical scheduling algorithms: earliest deadline first (EDF) and fixed priority (FP). Then, the derived schedulability conditions will be tightened, refining the analysis with a simple and effective technique that significantly improves the percentage of accepted task sets. The effectiveness of the proposed test is shown through an extensive set of synthetic experiments.     

Enhancing a dependable multiserver operating system with temporal protection via resource reservations

Nowadays, microkernel-based systems are getting studied and adopted with a renewed interest in a wide number of IT scenarios. Their advantages over classical monolithic solutions mainly concern the dependability domain. By being capable of dynamically detect and solve non-expected behaviours within its core components, a microkernel-based OS would eventually run forever with no need to be restarted. Dependability in this context mainly aims at isolating components from a spatial point of view: a microkernel-based system may definitely not be adopted in the context of real-time environments, simply basing on this kind of protection only. One of the most active real-time research areas concerns adding temporal protection mechanisms to general purpose operating systems. By making use of such mechanisms, these systems become suitable for being adopted in the context of time-sensitive domains. Microkernel-based systems have always been thought of as a kind of platform not suited to real-time contexts, due to the high latencies introduced by the message passing technique as the only inter-process communication (IPC) facility within the system. With computer performances growing at a fairly high rate, this overhead becomes negligible with respect to the typical real-time processing times. In the last years, many algorithms belonging to the class of the so-called Resource Reservations (RRES) have been devised in order to provide the systems with the needed temporal isolation. By introducing a RRES-aware scheduler in the context of a microkernel-based system, we may enrich it with the temporal benefits it needs in order to be deployed within domains with real-time requirements. In this paper we propose a generic way to implement these mechanisms, dependent for a very small part on the underlying OS mechanisms. In order to show the generality of our RRES framework we implemented it in the context of Minix 3, a highly dependable microkernel-based OS with an impressive users base.     

Analysis and implementation of the multiprocessor bandwidth inheritance protocol

The Multiprocessor Bandwidth Inheritance (M-BWI) protocol is an extension of the Bandwidth Inheritance (BWI) protocol for symmetric multiprocessor systems. Similar to Priority Inheritance, M-BWI lets a task that has locked a resource execute in the resource reservations of the blocked tasks, thus reducing their blocking time. The protocol is particularly suitable for open systems where different kinds of tasks dynamically arrive and leave, because it guarantees temporal isolation among independent subsets of tasks without requiring any information on their temporal parameters. Additionally, if the temporal parameters of the interacting tasks are known, it is possible to compute an upper bound to the interference suffered by a task due to other interacting tasks. Thus, it is possible to provide timing guarantees for a subset of interacting hard real-time tasks. Finally, the M-BWI protocol is neutral to the underlying scheduling policy: it can be implemented in global, clustered and semi-partitioned scheduling. After introducing the M-BWI protocol, in this paper we formally prove its isolation properties, and propose an algorithm to compute an upper bound to the interference suffered by a task. Then, we describe our implementation of the protocol for the?LITMUS ^RT real-time testbed, and measure its overhead. Finally, we compare M-BWI against FMLP and OMLP, two other protocols for resource sharing in multiprocessor systems.     

高等级住宅外墙外保温应用技术

为降低建筑采暖和空调制冷的能耗,贵都花园外墙采用外保温,介绍了墙体外保温用材、施工程序及操作工艺,竣工后通过热工性能检测,取得了明显的节能效果,并获安徽省“省级科技示范工程”称号。     

河北夏杖子金矿床的同位素地质研究

采用质谱分析等方法,测试了夏枚子金矿床石英流体包裹体和金属硫化物的同位素组成,获得石英流体包裹体Rb-Sr等时线年龄为105.4±7.2Ma;锶同位素初始比值为0.7126±0.0001;氢同位素组成δD‰为-91.7～-73.1;氧同位素组成δ~(18)OH_2O‰为5.68～6.23;金属硫化物的硫同位素组成δ~(34)S‰=-23.38～-14.52;铅同位素组成~(206)Pb/~(204)Pb=16.441～16.615,~(207)Pb/~(204)Pb=15.228～15.256,~(208)Pb/~(204)Pb=36.268～36.356。矿床成矿作用发生于燕山晚期,成矿热液主要为岩浆热液,金矿成矿物质来源于硅铝壳中下部太古代结晶基底,矿床成因是与燕山期岩浆热液有关的中—低温热液脉状金矿床。     

冶金企业实施CIMS总体方案的探讨——天津市轧三制钢有限公司CIM总体方案简介

对连续过程工业实施CIMS总体技术方案作了较为深入的探讨,并对天津市轧三制钢有限公司实施CIMS总体方案及技术路线进行了详细介绍。