An advanced geometric modeler GEMS4.0 has been developed, in whichfeature representation is used at the highest level abstraction of a productmodel. Boundary representation is used at the bottom level, while CSG modelis adopted at the median level. A BRep data structure capable of modelingnon-manifold is adopted. NURBS representation is used for all curved surfaces.Quadric surfaces have dual representations consisting of their geometric datasuch as radius, center point, and center tals. Boundary representat…

An explicit formula is developed to decompose a rational triangular Bezierpatch into three non-degenerate rational rectangular B6zier patches of the samedegree. This formula yields a stable algorithm to compute the control verticesof those three rectallgular subpatches. Some properties of the subdivision arediscussed and the formula is illustrated with an example.

In this paper, a new algorithm with extrapolation process for computingthe ray/surface intersection is presented. Also, a ray is defined to be the in-tersection of two planes, which are nonorthogonal in general, in such a waythat the number of multiplication operations is reduced. In the preprocessingstep, NURBS surfaces are subdivided adaptively into rational Bezier patches.Parallelepipeds are used to enclose the respective patches as tightly as possible.Therefore, for each ray that hits the enclosure (i.e…

This paper introduces a skeleton-based approach of automatically gener-ating DENG-XIAN, YUAN-TOU and HU-PO typefaces and discusses somealgorithms used in generating these fonts.

A key issue of dynamic load balancing in a loosely coupled distributed systemis selecting appropriate jobs to transfer. In this paper, a job selection policybased on on-line predicting behaviors of jobs is proposed. Thacing is used atthe beginning of execution of a job to predict the approkimate execution timeand resource requirements of the job so as to make a correct decision aboutwhether transferring the job is worthwhile. A dynamic load balancer using thejob selection policy has been implemelited. Exper…

SDL (Specification and Description Language) is an international standardformal description language which has been widely used for the specificationand description of communication systems. SDL is based on the concept ofthe state oriellted description technique - FSM (Finite State Machine). Thispaper reports an interactive generator for SDL, named SDL-TRAN, which canautomatically translate FSM expression into SDL description. Except for itsaatomatic translation part, SDLTRAN includes an userfriendly graPhi…

This paper presents a declarative semantics of compositional inheritancein an object-oriented logic programming' framework wit h explicit exceptions,based on the iterated least Aspoint semantics to normal logic programs. Tak-ing logic objects with exceptions as a ldnd of nonmonotonic theory, the nonmonotonicity of inheritance is achieved, which is of importance for modelingincomplete knowledge and requirement specffications in both artificial intelli-gence and softwa-re engineering.

A kind of classification on temporal relations of propositions is presented.By introducing temporal approaching relation, a new temporal logic based ontime-point and time-interval is proposed, which can describe uncertain temporalrelations. Finally some properties of temporal proposition under.uncertainrelations are proposed.

H-net is a Petri net based formal model of hyp ermedia/ hypert ext. Beingpowerful in the description of hypermedia, H-net can model the information inhypermedia and the knowledge of hypermedia naturally in a ullified Petri netbased wny. This makes H-net good for the modeling of intelligent hypermediasystems. In this paper, a unified reasoning algorithm is proposed to define thedynamic behavior of H-net. Using the Petri net theory based a.lgorithm, thereasoning in hypermedia information subnets, fuzzy produc…

An embedded system is a system that computer is used as a componelit ina larger device. In this paper, we study hybridity in embedded systems andpresent an interval based temporal logic to express and reason about hybridproperties of such ldnd of systems.