Liu Yu-sheng

3DTS: A 3D tolerancing system based on mathematical definition *

Tolerance is almost ubiquitous during the whole product lift cycle and is imperative for seamless integration of CAD and CAM. Based on the mathematical definition of tolerance, a 3D tolerancing system, 3DTS, is presented with its design principle, system architecture and key functions. The following functional modules, tolerance modeling, semantics interpretation, 3D tolerance analysis, are described in detail. To make the tolerancing system robust and efficient, many techniques such as hierarchical tolerance representation, rule-based evaluation and non-intersection determination of tolerance zone have been devised. Tested by many samples, this system shows good robustness and practicability.

Partial Relevance Feedback for 3D Model Retrieval

Relevance feedback (RF) proved an effect way to improve the precision and recall of 3D model retrieval. Unfortunately, through existing methods of RF, it is straightforward to find out whether a model is similar or not, but it is impossible to find out which local part is similar or not. The new partial method of RF proposed in this paper provides a good solution, in which not only the similar models are marked out but also the local parts which are similar or not are pointed out and taken advantage at the same time. This additional information contributes a lot to the improvement of 3D retrieval. Experiments show superiority in effectivity of the new method.

2D Partial Similarity Estimation Based on Energy Segmentation - I: Segmentation

How to perform partial similarity between models is still an open issue and attracts many attentions. Segmentation is regarded as one of the most critical and prospective steps for overcoming the task. An energy based segmentation approach for 2D curve is proposed in this paper. A curve is regarded as an elastic stripline(like spring) which has the balanced state and unbalanced state. Once it lies on the unbalanced state such as a spring elongated or compressed, it will possess the potential energy. Then the segmentation can be performed smoothly based on the energy and its attribute. Important is that no thresholds are required to initially determine the segmentation compared with the other methods. Also the proposed algorithm has several important and interesting properties such as robustness, independence,invariance and efficiency.

2D Partial Similarity Estimation Based on Energy Segmentation II. Feature based Similarity Calculation

How to perform partial similarity between models is still an open issue and attracts many attentions. Segmentation is regarded as one of the most critical and prospective steps for overcoming the task. An energy based segmentation approach for 2D curve is proposed in this paper. A curve is regarded as an elastic stripline(like spring) which has the balanced state and unbalanced state. Once it lies on the unbalanced state such as a spring elongated or compressed, it will possess the potential energy. Then the segmentation can be performed smoothly based on the energy and its attribute. Important is that no thresholds are required to initially determine the segmentation compared with the other methods. Also the proposed algorithm has several important and interesting properties such as robustness, independence, invariance and efficiency

Mask synthesis and verification based on geometric model for surface micro-machined MEMS

Traditional MEMS (microelectromechanical system) design methodology is not a structured method and has become an obstacle for MEMS creative design. In this paper, a novel method of mask synthesis and verification for surface micro-machined MEMS is proposed, which is based on the geometric model of a MEMS device. The, emphasis is focused on synthesizing the masks at the basis of the layer model generated from the geometric model of the MEMS device. The method is comprised of several steps; the correction of the layer model, the generation of initial masks and final masks including multi-layer etch masks, and mask simulation. Finally some test results are given.

A mathematical model of symmetry based on mathematical definition

Tolerance is imperative for seamless integration of CAD/CAM (Computer Aided Disign/Computer Aided Manufacture) which is just a text attribute and has no semantics in present CAD systems. There are many tolerance types, the relations between which are very complicated. In addition, the different principles of tolerance make study of tolerance difficult; and there may be various meanings or interpretation for the same type of tolerance because of the literal definition. In this work, latest unambiguous mathematical definition was applied to study, explain and clarfy: (1) the formation and representation of tolerance zone, and (2) the formation and representation of variational elements; after which, the mathematical models of symmetry of different tolerance principles and different interpretations were derived. An example is given to illustrate the application of these models in tolerance analysis.