Abstract:obility of computers introduces a new set of issues that were not present in distributed systems with static computers. Conventional routing algorithms are not suitable for such systems. The paper proposes an efficient, robust and scalable routing algorithm for mobile computers. It also discusses the consistency control and other characteristics of the approach, and compares with some related work.

Abstract:MIDS(mutitmedia intelligent database system) is an object database management system．Its database programming language is P++，which is based on C++．In the implementation of P++ the authors encountered the following problems：First，C++ pointer is ambiguous，not only can member pointer and reference pointer not be distinguished in semantics，but also volatile pointer and persistent pointer．This pointer ambiguity results in object locking problem in transaction management and others．Second, C++ objects that have virtual functions or virtual base classes contain memory pointers, which were not specified by the programmer．If such C++ objects are made persistent，then these pointers may be invalid across program invocations．Last，If the authors store object using file system call services，they should design complicated cache subsystem and a large amount of object format transformation，which demand a lot of memory and time．So they must find another solution storage scheme based on virtual memory mapping．

Abstract:It is well known that object-oriented data management will play a key role in engineering design data management system which is the base of a CAD framework. In this paper, the authors present their design and implementation of long transaction management, concurrency control, version management on network, etc. They have practically applicate them to their ECAD framework.

Abstract:Tsinghua drawing auto_input and management system，TH—DAIMS 2.0，is an image_based CAD system，which can be used in drawing renewal and drawing archival management．In TH—DAIMS 2.0，dynamic memory mapping makes it possible to process the drawings with large size and high DPI．Line picking speeds up the operations of interactive drawing modification and design．Edge smoothing improves drawing quality. Well defined structure of drawing database system is of benefit to its usage and maintenance．Chinese interface is more suitable for local users. And variable system structures can fit the different requirements of users．In the paper，the main functions and characteristics of TH—DAIMS 2.0 will be outlined, and some new techniques used in TH—DAIMS 2.0 will be described in detail.

Abstract:his paper first describes briefly the Bell-La Padula model used for secure computer system. Then an improved Bell-La Padula model is proposed according to the transferability of authorization of database system. It extends the elements of the original model and reforms the state of system, axioms and rules for state transition of the original model. The main conclusions of the improved model are presented and proved.

Abstract:ualitative simulation plays a central role in qualitative reasoning. This paper introduces the method of qualitative simulation with qualitative models, discusses some key techniques of the method, and demonstrates its applications in some areas.

Abstract:The software simulation of artificial neuraI networks，and the design，implementation and evaluation of parallel algorithm about artificial neural networks are highly important to the research and production of neural computers and the various of special neural VLSI chips. In this paper，a DMMPMS (distributed—memory，message—passing multiprocessor system) is constructed as a muhicomputer architecture for simulating the artificial neural network at first，which is implemented by a multi—transputer system of aring topology form．Next，an executable parallel computing model of DBP algorithm of muhilayered neural network on dynamic ring topology is proposed and implemented，which mainly includes the strategy of partition and map for neural cells；the parallel algorithms of the forward computation of activations，the backpropagation of errors and the update of weights. Then the time complexity and speed—up ratio of the DBP algorithm are investigated.

Abstract:In this paper, the authors propose a temporal approaching relation and give a sort of temporal relations of propositions, based on Shoham s temporal logic, they propose a temporal logic which can describe uncertainty relation and is based on time--point and time--interval in proposition and first order case. Finally, they give some properties of temporal proposition under uncertainty relations.