This paper presents a new and simple scheme to describe the convex hull in R~d,which only uses three kinds of the faces of the convex hull,i.e.,the d-1-faces,d-2-faces and 0-faces.Thus,we develop an efficient new algorithm for constructing the convex hull of a finite set of points incrementally. This algorithm employs much less storage and time than that of the previously-existing approaches.The analysis of the running time as well as the storage for the new algorithm is also theoretically made.The algorith…

Using vectors between control points(a_i=P_(i+1)-P_i),parameters λ and μ(such that a_(i+1)=λ_(ai+μ_(a_i+2))are used to study the shape classification of planar parametric cubic B-spline curves. The regiosn of λμ space corresponding to different geometric features on the curves are investigated.These results are useful for curve design.

In this paper,a new technique called test derivation is presented,aiming at the promotion of the random testing efficiency for combinational circuits.Combined with a fault simulator based on critical path tracing method,we introduce the concept of seed test derivation and attempt to generate a group of new tests from the seed test by means of critical path transition.The necessary conditions and effi- cient algorithms are proposed to guarantee the usefulness of the newly derived tests and the correctness of…

In this paper,a simulation system of pseudo-random testing is described first to investigate the characteristics of pseudo-random testing.Several interesting experimental results are obtained.It is found out that initial states of pseudo-random sequences have little effect on fault coverage.Fixed connection between LFSR outputs and circuit inputs in which the number of LFSR stages m is less than the number of circuit inputs n leads to low fault coverage,and the fault coverage is reduced as m decreases.The l…

In this paper,a survey of octree representation and its applications in CAD is presented.The octree representation may be categorized as pure octree representation and polytree(or extended octree),and the latter is actually a boundary representation decomposed by octree.Linear octree which is a variant of regular octree representation has the advantage of saving memory space. The mapping between Cartesian coordinates and node addresses in linear octree is discussed.Then, algorithms for converting a boundary…

HEPAPS is composed of constructive placement,improving placement,equivalence pins reassignment and same function elements reassignment.Based on practical demands,this paper imple- ments the constructive procedure within a set of engineering constraints and resolves the reassignment problems of equivalence and same function elements.A new topological improving method combined min-cut algorithm with simulated annealing algorithm is presented.In addition,the two-dimensional relaxed method is introduced to solv…

The Key problems in product modeling for integrated CAD∥CAM systems are the information structures and representations of products.They are taking more and more important roles in engi- neering applications.With the investigation on engineering product information and from the viewpoint of industrial process,in this paper,the information models are proposed and the definitions of the framework of product information are given.And then,the integration and the consistence of product information are discussed …

An algorithm has been obtained for solving the packing problem of placing convex polygons with different shapes and sizes into a rectangular vessel by simulating the elastic mechanics process,it is pointed out that,based on this algorithm,a sysem of computer-aided design can be developed for arranging two-dimensional materials.

In Ref.[1],we present a relation matrix description of temporal relation constraints.This pa- per is a sequel of [1].Given a set of temporal relation and time duration constraints,find a time-table which satisfies all the given conditions,that is called finding a D-time table.The construc- finn of D-time table and optimal D-time table and their computational complexity are discussed.

The characteristics peculiar to Chinese,especially Hanzi,processing with computers are described, and issues relevant to the portable application environment are reviewed.Though much of the des- cription concerns the localized issues,the way of consideration is applicable to those of portable, internationalized applications.

The following problem is called the everywhere-cover problem:“Given a set of dependencies over a database scheme,is the set of dependencies explicitly given for each relation scheme equivalent to the dependencies implied for that relation scheme?”It is shown that when the everywhere-cover problem has a ‘yes’ answer,examining only the dependencies explicitly given will suffice to test 3NF,BCNF and 4NF of a database scheme.But this does not hold for 2NF.Consequently,in such cases,tests of BCNF and 4NF all tak…

In this paper,a new scheme for recovering errors due to transient faults in a real-time multiprocessor system is presented.The scheme,called dynamic redundancy at the task level,is implemented in a real-time multitasking environment.Utilizing the facilities in the operating system,the scheme makes backup tasks for the primary tasks as redundancy.The paper introduces an algorithm to gene- rate a fault tolerant schedule for the tasks so that they recover errors as retry or checkpointing does.A reliability mod…

A simplified version of the extension matrix algorithm has been proved to be useful for implementation on a cellular automata machine (CAM-6).The algorithm and its implementation are described

This paper presents the use of a student model to improve the explanations provided by an intelligent tu- toring system,namely SimpleQuestl,in the domain of electronics.The method of overlay modelling is adopted to build the student model.The diagnosis is based on the comparison of the behavinurs of the student and the ex- pert.The student model is consulted by the “explainer” and “debugging” procedures in order to re-order the sequence of the explanation.