18261046
Shelling Algorithm in Solid Modeling
Shelling is a powerful modeling operation in current CAD /CAM systems. In this paper, we present a new shelling algorithm for regular B-Rep solids. We first generate an initial offset solid, then correct the self-intersecting offset solid if necessary. We obtain the resultant shelling solid through a regularized Boolean operation finally. The algorithm has been implemented in a solid modeling system, and some examples are given to illustrate it.
16104127
Bilateral Filter for Meshes Using New Predictor
A new predictor of bilateral filter for smoothing meshes is presented. It prevents shrinkage of corners. A major feature of mesh smoothing is to move every vertex along the direction determined by the mean curvature normal with speed defined by the predictor. It prevents unnatural deformation for irregular meshes. In order to remove thenormal noise, we use adaptive Gaussian filter to smooth triangle normals.
37845872
The complexity of learning in PLN networks
Abstract In this paper, the complexity of learning in the feedforward PLN network is investigated by using Markov chain theory, when its training samples are incomplete (i.e., a network with hidden nodes). We present a learning algorithm. A formula for computing the average number of steps that the learning algorithm converges is obtained when the PLN network exists a solution. In the probabilistic sense, the completeness of the learning algorithm is proved. Some computer simulations are given to verify the analysis.
6715931
Evaluating guidelines for empirical software engineering studies
Background. Several researchers have criticized the standards of performing and reporting empirical studies in software engineering. In order to address this problem, Andreas Jedlitschka and Dietmar Pfahl have produced reporting guidelines for controlled experiments in software engineering. They pointed out that their guidelines needed evaluation. We agree that guidelines need to be evaluated before they can be widely adopted. If guidelines are flawed, they will cause more problems that they solve.Aim. The aim of this paper is to present the method we used to evaluate the guidelines and report the results of our evaluation exercise. We suggest our evaluation process may be of more general use if reporting guidelines for other types of empirical study are developed.Method. We used perspective-based inspections to perform a theoretical evaluation of the guidelines. A separate inspection was performed for each perspective. The perspectives used were: Researcher, Practitioner/Consultant, Meta-analyst, Replicator, Reviewer and Author. Apart from the Author perspective, the inspections were based on a set of questions derived by brainstorming. The inspection using the Author perspective reviewed each section of the guidelines sequentially. Results. The question-based perspective inspections detected 42 issues where the guidelines would benefit from amendment or clarification and 8 defects.Conclusions. Reporting guidelines need to specify what information goes into what section and avoid excessive duplication. Software engineering researchers need to be cautious about adopting reporting guidelines that differ from those used by other disciplines. The current guidelines need to be revised and the revised guidelines need to be subjected to further theoretical and empirical validation. Perspective-based inspection is a useful validation method but the practitioner/consultant perspective presents difficulties.
14763506
Real-time voxelization for complex polygonal models
In this paper, we present an efficient voxelization algorithm for complex polygonal models by exploiting newest programmable graphics hardware. We first convert the model into three discrete voxel spaces according to its surface orientation. The resultant voxels are encoded as 2D textures and stored in three intermediate sheet buffers called directional sheet buffers. These buffers are finally synthesized into one worksheet, which records the volumetric representation of the target. The whole algorithm traverses the geometric model only once and is accomplished entirely in GPU (graphics processing unit), achieving real-time frame rate for models with up to 2 million triangles.
46427487
The Clar Covering Polynomial of Hexagonal Systems I
Abstract In this paper the Clar covering polynomial of a hexagonal system is introduced. In fact it is a kind of F polynomial [4] of a graph, and can be calculated by recurrence relations. We show that the number of aromatic sextets (in a Clar formula), the number of Clar formulas, the number of Kekule structures and the first Herndon number for any Kekulean hexagonal system can be easily obtained by its Clar covering polynomial. In addition, we give some theorems to calculate the Clar covering polynomial of a hexagonal system. As examples we finally derive the explicit expressions of the Clar covering polynomials for some small hexagonal systems and several types of catacondensed hexagonal systems. A relation between the resonance energy and the Clar covering polynomial of a hexagonal system is considered in the next paper.
21780190
A general numerical procedure for multilayer multistep IC process simulation
A new numerical procedure is presented for the simulation of multistep processes in IC fabrication of nonplanar multilayered structures. The numerical scheme utilizes a multizone adaptive grid generation (MAGG) technique for the discretization of the physical domains of arbitrary shape that may involve free or moving boundaries. The process model equations are discretized in the physical space using a curvilinear finite-volume formulation. The numerical scheme is validated by simulating silicon oxidation process (with the inclusion of stress effects) on a 50/spl deg/ trench and comparing the results with the published SEM photographic data. Capabilities of the methodology, including geometric flexibility, efficiency in grid distribution, accuracy in treating the moving boundaries, and facility for modification of the physical model are discussed. These characteristics are demonstrated by simulating simultaneous silicon oxidation and impurity diffusion in trench structures with corner angles equal to, and greater than, 90/spl deg/. >