Abstract:Many real-time systems have hard deadline periodic tasks along with soft deadline aperiodic tasks. An algorithm to improve response time of soft aperiodic tasks is presented in this paper. Existing methods of scheduling both periodic and aperiodic tasks are all based on RM (rate monotonic) scheme. Among them, stealing slack time from periodic tasks has been proved to be an optimal method. However, the RM scheme limits the processor utilization, therefore limits the stealable time of periodic tasks. The potential processor utilization of the DD (deadline driven) scheme can reach 100%. The presented algorithm applies the DD scheme to periodic task scheduling as it needs, and shortens the response time of aperiodic tasks. The experimental results show that the new algorithm provides performance higher than all existing algorithms, and the increased run-time overhead is not very high.

Abstract:Line clipping is one of the fundamental problems in computer graphics. In this paper, two well known algorithms are analyzed and a new algorithm, which simplifies the line clipping into the processes in two basic cases by doing simple transformation on two end points of a line in turn, is introduced. The algorithm effectively overrides the shortcomings existed in the above two algorithms such as too many subroutine calls and complex basic cases. Both theoretic analysis and example testing show that the new algorithm is better than well known algorithms.

Abstract:In this paper, the performance evaluation of a dynamically adaptive co-scheduling algorithm——Dasic based on network of workstations is presented. In terms of the aspects of mean response time and system flow, the Dasic algorithm is compared with traditional co-scheduling algorithm MAX and Grab algorithm by simulation. The conclusion is that dynamic adaptation can strikingly improve co-scheduling performance in a massive system of network of workstations.

Abstract:Color management has become an important technical support of operating system to provide consistent and quality color reproduction across various devices and platforms. This great improvement is the result of efforts of ICC group. However, there are various techniques and ways to implement ICC-based color management system, and in fact, the standard method does not provide a complete solution for all situation. Therefore, the authors try to give a survey about ICC-based color management technologies on computer. The content includes basic color knowledge, overview of different implement stratagems of color management (focusing on ICC-based), existing problems and future research directions of color management.

Abstract:Most recently, attention has focused on adaptive interface in the human-computer interface domain. In this paper, several fundamental concepts of adaptive interface are introduced at first, then an adaptive mechanism of user interface is presented based on these concepts. The structure and technology of this architecture are discussed in detail. This architecture has been applied to GS-ICCC (GreatSky-Integrated CAD, CAPP and CAM), which is an integrated CAD/CAPP/CAM system. Some details when implementing this architecture are also described. The adaptive architecture of GS-ICCC has been implemented based on X-Window/Motif environments. It has been proved to be highly efficient.

Abstract:The function construction and checking system FC (function constructor) is a component of SAQ (specification acquisition) which utilizes CFRFs (recursive functions defined on context-free languages) to represent the semantics of a specification. FC provides the interactive and inductive definition, and the evaluation of CFRF, supporting mutually recursive definition process of CFRFs. In this paper, the functions, structure and implementation details of FC are described, the possible improvement is discussed.

Abstract:With the structure and behavior encapsulated in object, object database supplies large complex applications with better modeling capacity and implementation utilities. Deductive object database results from the integration of object and logic. However, deductive object database focuses more on object structure description and less on object behavior description. In the present paper, the authors study the object dynamic behavior analyze the interaction among inheritance, overriding and transaction, and gives a language called TOL (transaction object base language). The elementary actions in TOL are analyzed first, and then a model semantics is built based on path structure for transactions.

Abstract:In this paper, lossless image coding techniques are discussed first, then a lossless image coding method based on block direction prediction and context is presented. It removed the redundancy of the image in spatial domain by block direction prediction and context-based error modeling. In the proposed method, an image is first partitioned into blocks. Then, a direction predictor that results in minimum prediction error is adaptively selected for each block. After that, context selection and error feedback are applied to further reduce the entropy. A fast and efficient Rice coder is applied finally for the residual image coding. The experimental results show that the proposed method significantly outperforms over JPEG (joint of picture expert group) lossless mode and FELICS (fast and efficient lossless image compression), and it obtains comparison ratio superior to CB9, LOCO-I, even UCM.

Abstract:The integration of deductive database and object database results in deductive object database which has capacities of deductive query of deductive database and strong modeling of object database. DOL (deductive object base language) is designed as a deductive object base language. It supports class, object identifier, complex object, partial set, inheritance and overriding. A immediate consequent operator, similar to tradition's, is defined based on two operators: compact operator and overriding operator in this paper. In addition, a fixed point semantics is analyzed.

Abstract:An incremental updating technique called FAST is proposed in order to deal with the maintenance of discovered generalized sequential patterns resulted from the change of the minimum support. The main idea is to re-utilize the results acquired in process with the old minimum support.

Abstract:The technologies of object store are the cores of OMS (object management system). Many persons have done a lot of efforts. The ObjectCore——the object store system of the ISPE (integrated software process environment) object management system is discussed in this paper. And some important aspects of technologies of object store of OMS are discussed as well.

Abstract:Optimizing the CAI (computer assisted instruction) hypertext knowledge base is one of the keys for improving quality of CAI courseware. First, the structure of knowledge points and the mathematical description of their networks are given in the paper. Then the parallel network traveling in “learn first use later” or “learn right use right” manner and the single destination network traveling are given by some layer partitions of network nodes. Some algorithms of reducing the network structure to save storage space and ease operating are introduced. Finally, optimizing the CAI hypertext knowledge base by means of the network properties is summarized.

Abstract:Based on the fungal growth model, the authors develop an environmentally-adaptive parametric L-system and present a fractal image generation algorithm in this paper. This algorithm not only uses biological understanding of the flow of nutrients through the fungus to control the growth, but also takes the influence of the environment which fungus grow in into full account. The images generated by this algorithm have natural branching structure. By setting the environmental factor, its global-shape feature can be easily controlled. It is especially suitable for industrial pattern design, animation image design and so on.

Abstract:A global search algorithm, competition algorithm, is presented. It searches for the global optimum by impelling and competing among the individuals within a population. The idea of the proposed algorithm is independent of the famous GA(genetic algorithm). Some computations on combinatorial optimization problem are conducted, which demonstrate the superiority of the algorithm.

Abstract:Optimization of decision-tree is a significant branch in decision-tree learning algorithm. An optimized learning algorithm of ID3, a typical decision-tree learning algorithm is presented in this paper. When the algorithm selects a new attribute, not only the information gain of the current attribute, but also the information gain of succeeding attributes of this attribute is taken into consideration. In other words, the information gain of attributes in two levels of the decision tree is used. The computational complexity of the modified ID3 (MID3) is the same as that of the ID3. When the two algorithms are applied to learning logic expressions, the performance of MID3 is better than that of ID3.