This paper presents a practical concurrency control mechanism - ObjectLockingin OODBMS. Object-Locking can schedule transactions, each of themcan be considered as a sequence of high level operations defined on classes. Bythe properties of parallelity and coatativity between high level operations,proper lock modes for each operation are desigued and the compatibility matrixis constructed. With these lock modes, phatoms are kept away from databasesand a high degree of concurrency is achieved.

This paper reports an algorithm (DTV) for deterdring the minimal reducedcovering of an acyclic database scheme over a specified subset of attributes. The output of this algorithm contains not only minimum number of attributes but also minimum number of partial relation schemes. The algorithm has complexity O(|N|·|E|2), where |N| is the number of attributes and |E| the number of relation schemes- It is also proved that for Berge, γ orβ acyclic database schemes, the output of algorithm DTV maintains the acyc…

In complex object oriented databases, the purpose of introducing class hierarchy is to express ISA sematics, to realize inheriting and to reuse schema definition codes. The schema definition and schema evolution, based on the partial order of lattice, often cause the loss of information inheriting and the redundance of schema dedrition. Based on the fullness of the inheritance shownby class hierarchy three normal forms of class hierarchy are given in this paper, and a general algorithm of normalization of c…

The research on Temporal Databases (TDB) has been a hot topic for quite along time, but few implementations have been reported. The authors have developeda prototroe of temporal DBMS in DOS/Windows envirorunent, calledHBase. This paper discusses its temporal structure, temporal syntax and semanics,as well as the special techniques used in the Anplementation of HBase.

This paper proposes an approach to diagnostic reasoning with the followingdistinct features: ① A diagnostic system is formulated in FoL with equality,particularly in the form of program clauses; ② The abnormality of system　components is determined in terms of either experiential knowledge of domain experts or behavioral description of components; ③ Heuristics is fully used not only to assist in judging the abnormality of system components, but also to guide the diagnosis; ④ A uaique diagnosis will be comput…

This paper presents a new method for behavior fusion control of a mobile robot in uncertain environments. Using behavior fusion by fuzzy logic, a mobile robot is able to directly execute its motion according to range information about environments, acquired by ultrasonic sensorst without the need for trajectory planning. Based on low-level behavior control, an efficient strategy for integrating high-level global planning for robot motion can be formulated, since,in most applications, some information on env…

Multistage Interconnection Networks (MINs) are often used to provide interconnections in multiprocessor systems. A unique path MIN usually has lower hardware complekity and a simple control algorithm, but it lacks fault tolerance.This paper proposes a kind of multipath MINs, which are obtained by adding auxiliary links at the final stage in Quad nee (QT) networks so that they canprovide more paths between each source-destination pair, and presents theirrouting algorithm which is both destination tag based a…

The management of memory coherence is an important problem in distributed shared memory (DSM) system. In a cache-based coherence DSM system using linked list structure, the key to maintaining the coherence and improving system performance is how to manage the owner in the linked list. This paper presents the design of a new management protocol-NONH (New-OwnerNew-Head) and its performance evaluation. The analysis results show that thisprotocol can improve the scalability and performence of a coherent DSM sys…

The normal form and modilied normal form for binary redundant representation are defined. A redundant binary algorithm to compute modular exponentiation for very large integers is proposed. It is shown that the proposed algorithm requires the minimum number of basic operations (modular multiplications) among all possible binary redundant representations.

In this paper, several kinds of multivalued logic for relational database and their developing process are presented on the basis of null value's semantics. A new 5 valued logic is led into relational database containing null talue. The feasibility and necessity of using 5 valued logic are expounded. Comparative calculation and logical calculation under 5 valued logic are defined at the end of the paper.

There are several purposes of analyzing a program: functional or performance analysis, debugging or, more recently, mapping a program to a new parallel or distributed architecture. In this paper, we introduce an effective method leading to the Execution Graph (EG) from a program. First,the Unix profiling tool Gprof is used to get the Execution Model (EM) of a C-program. Then the event-driven monitoring tool AICOS-SIMPLE is used to get the EG which includes not only the call graph but also the execution time…

It is a key feature to embed 3D realistic sound effect in the future multimedia and virtual reality systems. Recent research on acoustics and psychoacoustics reveals the important cues for sound localization and sound perception. One promising approach to generate 3D realistic sound effect uses two earphones by simulating the sound waveforms from sound source to eardrum. This paper summarizes two methods for generating 3D realistic sound and points out their inherent drawbacks. To overcome these drawbacks w…