QoS-aware radio resource management scheme for CDMA cellular networks based on dynamic interference guard margin (IGM)

Efficient radio resource management (RRM) for CDMA-based cellular communication systems using the interference guard margin (IGM) scheme is investigated in this work. Two important concepts, i.e., the guard channel (GC) and the load curve (LC), are integrated to derive IGM. The resulting call admission control (CAC) scheme gives preferential treatment to higher priority handoff calls by pre-reserving a certain amount of resource in terms of IGM. A radio resource estimation (RRE) function is implemented in each base station (BS) to assist RRM module to adjust the level of IGM dynamically. RRE in each BS estimates the amount of IGM by considering traffic load in its current cell as well as traffic conditions in neighboring cells. A service model is adopted to support quality of service (QoS) demand of multiple services, which includes mobile terminal’s data rate, different levels of priorities, mobility and rate adaptivity characteristics. Simulations are conducted by OPNET to study performance of the proposed IGM scheme in terms of a defined cost function, new call blocking probability, handoff dropping probability and system utilization, under different traffic conditions.     

A flexible communications protocol for a distributed surveillance system

On-line surveillance for safety and security is a major requirement of public transport and other public places to address the modern demands of mobility in major urban areas and to effect improvements in quality of life and environment protection. The surveillance task is a complex one involving technology, management procedures and people. Visual surveillance based on Closed Circuit Television system is an important part of such systems, but visual processing is not sufficient and the geographical distribution of devices and management has to be taken into account. In this paper we present a surveillance architecture that reflects the distributed nature of the monitoring task and allows for distributed detection processes, not only dealing with visual processing but also with devices such as acoustic signature detection and mobile smart cards, actuators and a range of other possible sensors. The design uses ideas from control engineering and distributed communications networks resulting in a communications architecture based on CORBA and XML messaging. We have shown how to define a generic device/sensor model appropriate for the surveillance task and sufficiently flexible so as to allow for scalability, expansion and customisation of a practical surveillance task. The paper gives sufficient details on the protocols to show how intelligent detection modules can be integrated as part of this kind of system. The system components have been implemented and integrated in two major successful trials in metropolitan railway stations in London and in Paris, as part of a major EU-funded project (PRISMATICA).     

A cooperative agent-based model for active security systems

This paper presents a multi-agent model for implementing active security concepts. In this model, a group of agents can carry out their tasks cooperatively in order to achieve an ultimate security goal. Thus a low-level module of the proposed model reads the values of interesting data items of the relevant current network events and passes them to a relational database. Comparing these measurements against predefined values in an intruder signature database may point to a particular attack.The proposed model consists of two parts. (1) A multiagent Intrusion Detection System (MIDS) for detecting attacks. (2) An Active Security Mechanism (ASM) for taking active, network-wide, response against attackers. The proposed approach provides a customizable host environment built from various systems software components to allow an optimal match between the intrusion circumstances and the underlying security architecture. Thus, different frameworks can support alternative responses of existing security services. In addition, the ASM can take rapid response against attacks by making use of sensible sharing of attack intelligence. System agents communicate with each other on different hosts using an agent communication language through a message router.     

一台用于AMS的鉴别同量异位素的气体电离室

文章描述一台用于加速器质谱计(AMS)的鉴别同量异位素的气体电离室,它由三个分离的阳极、一个栅极和阴极组成。利用这台电离室,在加速器上进行了~(36)Cl的测定。它有效地排除了~(36)S等本底的干扰。     

Education and training for CAD in the auto industry

CAD-systems envisioned and remarkably well specified in the 1950s have powered themselves into the central role they enjoy in today's automotive industry through continuous improvements and technological breakthroughs. This paper emphasizes the parallel and continuing evolution in the training and educational needs of users of CAD-systems. In the context of early historical developments of CAD at General Motors, this paper categorizes CAD-users in the automobile industry and presents their current and future needs. The variance in their educational and training needs poses an ongoing challenge for educational and industrial institutions to meet.     

A generalization of the E-LOTOS renaming operator: a convenience for specification of new forms of process composition

E-LOTOS is one of the standard languages for formal specification of real-time concurrent and reactive systems. As it is process-algebraic, its expressive power lies in its process-composition operators. Of course, not all forms of composition can be directly expressed in the language. In the most difficult cases, one typically resorts to the constraint-oriented specification style. We demonstrate that a slight enhancement of the E-LOTOS renaming operator would make the specification style even more powerful. As an example, we show how to specify choice, parallel composition and disabling enhanced with action priorities.     

Development of novel rare earth doped fluoride and oxide scintillators for two-dimensional imaging

Two topics were focused.The first one was about the gamma-ray scintillator,Pr3+:Lu3Al5O12(LuAG) .The second one was about neutron scintillator,Ce3+:6LiCaAlF6 and Eu2+:6LiCaAlF6(6LiCAF) .Those scintillators have been developed very recently for modern imaging appli-cations in the medical and homeland security fields.In both cases,the rare earth ions are playing the crucial role as emission centers.Pr3+ in LuAG provided fast 5d→4f transition providing noticeably shorter decay time than that of Ce3+.Among several candidate hosts,LuAG showed the best performance.Bulk crystal growth,basic scintillation properties,two-dimensional gamma-ray imaging and positron emission mammography(PEM) application were demonstrated.Due to the international situation,the homeland security was compromized by illicit traffic of explosives,drugs,nuclear materials,etc.and the ways to its improvement became an important R&D topic.For this purpose the Ce and Eu doped LiCAF ap-peared competitive candidates.Especially,when substitution of 3He neutron detectors was considered,the discrimination ability of gamma-ray from alpha-ray was important.Bulk crystal growth,basic scintillation properties and two-dimensional neutron imaging were demonstrated.     

High-strain-rate superplasticity in oxide ceramics:a trial of microstructural design based on creep-cavitation mechanisms

From existing knowledge about high-temperature cavitation mechanisms,necessary conditions were discussed for the suppression of cavitation failure during superplastic deformation in ceramic materials.The discussion,where special attention was placed on the relaxation of stress concentrations during grain-boundary sliding and cavity nucleation and growth,leaded to a conclusion that cavitation failure could be retarded by the simultaneous controlling of the initial grain size,the number of residual defects,diffusivity,dynamic grain growth and the homogeneity of microstructure.On the basis of this conclusion,high-strain-rate superplasticity (defined as superplasticity at a strain rate higher than 0.01 s-1) could be intentionally attained in some oxide ceramic materials.This was shown in tetragonal zirconia and composites consisting of zirconia,α-alumina and a spinel phase.     

China review: Status and potential of renewable energy in China

Renewable energy is in a rapid development stage in China, and some technologies are in commercialisation or near commercialisation and have large development potential from resource, technology and industry points. Renewable energy has begun to play a role in the energy structure, and it has the potential for large scale development. According to the national target, renewable power will represent 12% of the total power capacity in China in 2020. It is expected that it will reach 30% or even more in the 2040s and renewable energy will be an important substitute energy at that time.