基于分度台转位装置的惯性测量单元智能检测

针对惯性测量单元(IMU)批量检测效率低、人工劳动量大的现状,设计开发出一种基于分度台转位装置的IMU智能检测系统。其采用高精度分度台转位装置为IMU提供基准角度位置,利用工控机控制分度台转位装置、程控直流电源和IMU协调有序工作,通过上位机软件智能控制程控直流电源向IMU供电,以及自动发送、采集、分析和处理检测数据,实现对IMU的智能、高效、精确检测。实验结果表明,该系统可同时自动检测4套IMU 的参数指标,并自动计算、显示和保存检测数据,且检测精度、效率和智能化程度高,人工劳动量小,性价比高,此外,软件界面上所有功能均可手动触摸操控,操作十分便捷。     

Automatic recognition and suppression of holes on mold bases for finite element applications

Engineering with Computers - As the required accuracy of mold flow analysis has recently increased, it has become necessary to consider all components of a mold base and to generate solid meshes...     

Unconstrained and constrained curve fitting for reverse engineering

Curve fitting is commonly used in reverse engineering for the reconstruction of curves from measured points, and it is critically important to provide various kinds of curve-fitting algorithms to acquire curves that satisfy different constraint conditions. We divide the curve-fitting problem into unconstrained and constrained types. For the unconstrained type, three curve-fitting algorithms are investigated: general, smooth and extended curve fitting. The general curve fitting considers only the accuracy of the fitted curve; the smooth curve fitting can control both the accuracy and the fairness of the fitted curve, while the extended curve fitting can acquire a curve longer than the range of the measured points. For the constrained type, we propose three curve-fitting conditions: fixed end-points, closed curve and continuity to adjacent curves. Detailed discussion for each of the above cases is presented. Associated examples are also provided to illustrate the feasibility of the proposed algorithms.     

Recognition of virtual loops on 3D CAD models based on the B-rep model

Loops are critical elements in boundary representation (B-rep) models because they link all edges corresponding to a face. Loops can be used in feature recognition for identifying depressions or protrusions. In real 3D CAD models, however, features typically lie across multiple faces, which is beyond the data structure of current B-rep models. This study presents a virtual loop concept to account for all loop types used in CAD models, and develops algorithms for recognizing them. In accordance with the complexity of the recognition algorithm, this study defines three types of loop: single, virtual, and multivirtual. A single loop is the current loop recorded in the B-rep model. A virtual loop lies across faces that are at least G¹ continuous. Finally, a multivirtual loop lies across faces that are either G⁰ or G¹ continuous. The proposed loop structure provides a more complete data structure for recognizing various types of features in feature-recognition modules. Several realistic CAD models are presented to confirm the feasibility of the proposed loop-recognition and feature-recognition methods.     

Constructive role of noise in p53 regulatory network

We study the effect of noise on p53 regulatory network, the core of a cell's modulator for switching between survival and apoptosis. We find that the fluctuations, originating from stochastic expression of p53-responsive genes, introduce marked advantages for the system to sense external stimuli and sustain the function of switches. The coherence between a stimulus and the system's response undergoes a maximum with the raise of noise level, indicating the occurrence of stochastic resonance. The biological significance of our results is discussed.     

Enhancement of condominium management based on the effect of quality attributes on satisfaction improvement

Condominium management (CM) businesses rely on continuous improvements to service quality (SQ) to increase consumer satisfaction (CS) and thereby improve operations. Lacking knowledge of SQ and CS results in poor efficiency. To develop cost-effective strategies for improvements, the relationship between SQ and CS must be investigated. This work proposes novel procedures to explore the relationship between identified SQ attributes and CS in the CM business. First, we conduct exploratory factor analysis to cluster intrinsically similar attributes into three constructs and identify significant attributes for subsequent assessment. Furthermore, resident satisfaction scores (RSSs) are computed to assess the relative importance rate (RIR) of investigated attributes by applying an adapted multivariate method to regress the RSSs on the performance of SQ attributes. To facilitate the decision-making process, the service-quality model evolved from the integration of an improved Kano’s approach and importance-performance analysis (IPA) is utilized to develop a prioritized strategy for satisfaction improvements in the CM business.     

Automatic reconstruction of B-spline surfaces with constrained boundaries

The aim of this study is to present an automatic surface reconstruction method that can take practical restrictions on scanned points into consideration and efficiently and reliably output a group of G¹ surfaces. The proposed method is mainly composed of three phases: quadrangle frame generation, point and curve networks planning, and surface patches reconstruction. In the first phase, the original triangle mesh is reduced and converted into a quadrangle mesh, the edges of which serve as the frame of the surfaces. In the second phase, the boundary data of the surfaces are prepared. These include a network of serial points, frame curves and surface normals which are also expressed as curves. In the final phase, surface initialization, harmonization mapping and surface warping are presented to yield the desired surfaces. The main advantage of the proposed method is that it can relax the pre-processing of a scanned triangle mesh, and hence, increase the efficiency and quality of the surface reconstruction. Several examples of various types of air bags are presented to demonstrate the feasibility of the proposed method.     

Small blend suppression from B-rep models in computer-aided engineering analysis

In mechanical design, small blending is a common operation used to improve the strength and aesthetics of the workpiece. In blending operations, certain smooth faces are added to the boundary representation (B-rep) model to smooth sharp edges and vertices. These faces are termed ‘blend faces.’ However, they may affect the quality of analysis; these faces should be meshed with tiny meshes, which may result in an increase in computational time and reduced accuracy of simulation results. Hence, small blend suppression is an approach for improving the quality of generated meshes. Blend suppression is a technique for reverting a blended computer-aided design model to its original unblended status. This study proposes a blend suppression algorithm for removing blend faces in computer-aided engineering (CAE) analysis. The proposed algorithm operates as follows: (1) edge blend faces and vertex blend faces are grouped individually, (2) new geometric data are computed, (3) new elements are added to the data structure of the B-rep model, (4) all data related to blend faces are deleted, and (5) all topological data in the B-rep model are updated. Several examples are presented in this paper to demonstrate the feasibility of the proposed method for blend suppression as well as its advantage in improving the quality of meshes in CAE analysis.     

The finite element method by employing the singular element with concordant displacement at the crack tip

A new regular polygon singular element is presented here. Its displacement is divided into two parts—linear and singular, the latter including the stress intensity factors vanishes on the boundary of the singular element, so the continuity of the displacement is satisfied. Furthermore, each element in the singular stiffness matrix can be expressed in some more simple analytic formulas. The procedure of analysing and reasoning of this technique is given in this paper, with which the intensity factors of the three kinds of loading system—uniform tension, three-point bending and shearing—are calculated. The results of the calculation show that this method is successful.