平面并联机构工作空间的三维螺旋扫描CAD求解

针对平面并联机构无奇异位置工作空间求解困难、过程繁琐、计算量大等问题，提出了基于CAD求解平面并联机构工作空间的三维螺旋扫描方法。将[n]自由度平面并联机构分解成[n]条支链进行独立分析，得到每条支链下末端执行器的可达区域，再将所有支链可达区域取交集即为平面并联机构工作空间。应用SolidWorks软件建立平面并联机构模型，进行几何特征处理，通过自动求解器求解，将求解过程图形化，快速得到同轴布局5R机构和平面3-RPR并联机构的无奇异位置工作空间。通过同轴布局5R机构的运动学实验，验证了该求解方法的可行性。     

A computer aided design method for car form and its application based on shape parameters

In the early design stage, automotive modeling should both meet the requirements of aesthetics and engineering. Therefore, a vehicle CAD (computer aided design) model that can be easily adjusted by feedbacks is necessary. Based on CE-Bézier surface, this paper presents a set of algorithms for parametric segmentation and fairing surface generation in a car model. This model is defined by a simplified automotive template and relevant control points, shape parameters and segmentation parameters, which can be modified to alter the car form efficiently. With this model and the corresponding adjustment method, more than fifty various vehicle models are established in this research according to different parameters. And two methods for calculating similarity index between car models are constructed, which are suitable for brand design trend analysis and modelling design decisionmaking.     

Assessing the impact of geometric design intent annotations on parametric model alteration activities

The effective representation and communication of design intent plays a crucial role in CAD model alteration activities. In history-based parametric modeling systems, design intent information is usually expressed implicitly within the model. However, there is evidence that suggests that an explicit representation can increase productivity and quality and facilitate the transferring of design knowledge throughout the different stages of the product lifecycle. In this paper, we assess the effectiveness of 3D annotations as mechanisms for explicit design intent representation and examine their impact in model alteration processes that require a direct interaction with the model's geometry. We present the results of a series of studies aimed at measuring user performance and model quality in two scenarios. First, we hypothesized that annotations are valuable tools to provide design information when inadequate modeling assumptions can be made by designers. Second, we evaluated annotations as tools to communicate design decisions when multiple options are available. In both cases, results show statistically significant benefits of annotated models, suggesting the use of this technique as a valuable approach to improve design intent communication.     

Design and optimization of zirconia functional surfaces for dental implants applications

Zirconia is becoming a promising solution for biomedical applications, namely for dental implants, due to its biocompatibility, and mechanical and aesthetical properties. Despite the constant developments in the dentistry field, strategies to promote an effective vascularization at the implant's surface and consequently improved osseointegration are still not enough.In this sense, with the aim of promoting the vascularization at the implant's surface, zirconia surfaces with micro-channels were designed and evaluated regarding their hydrophilicity and capillarity. A CAD/CAM system was used to design and produce the specimens and different techniques were used to characterize the surfaces. The obtained average surface roughnesses are in accordance with the literature for similar materials. Results revealed that the produced materials present high levels of hydrophilicity, whether in contact with water or FBS - Fetal Bovine Serum. Additionally, micro-channels with 200 μm of width and 100 μm of depth were the ones that presented higher capillarity, thus being promising solutions for the promotion of implants vascularization, and consequently improved osseointegration.     

From regional sensitivity to intra-sensitivity for parametric analysis of free-form shapes: Application to ship design

Robust Parametric Sensitivity Analysis (PSA) is a prerequisite for efficient shape optimisation via parametric modelling. A major challenge PSA has to handle is related to the fact that a parameter can be sensitive in certain local areas of the design space but become insensitive in others. Therefore, setting an applicable space for this analysis becomes a difficult task. In this paper, we introduce the concept of intra-sensitivity to identify parameters whose perturbation has a major impact on the sensitivity index of the remaining parameters. For this purpose, we firstly appeal to Active Subspace Method (ASM) and develop an ASM-based regional sensitivity analysis, which investigates parametric sensitivity in local regions of the design space and aids conducing to parameters’ intra-sensitivity. This regional analysis is applied in conjunction with a Dynamic Propagation Sampling approach, for tackling the computational complexity arising when high-dimensional problems are concerned. Once sensitive and intra-sensitive parameters are identified, then free-form features, correlated to these parameters, are evaluated using a feature saliency map built with the aid of Hausdorff distance. The so resulting methodology has been validated in the area of computer-aided ship design using two parametric modellers: the first one is a Procedural Deformation (PD) modeller which is based on T-splines and involves 24 parameters while the second one is based on Free-Form Deformation (FFD) and involves 104 parameters. The corresponding design spaces have been generated using a parent hull close to the KCS container ship and are analysed against hull’s volume of displacement and total resistance. Finally, the convergence performance of the various components of this approach is compared with state-of-the-art techniques.     

Engineering knowledge formalization and proposition for informatics development towards a CAD-integrated DfX system for product design

Target design methodologies (DfX) were developed to cope with specific engineering design issues such as cost-effectiveness, manufacturability, assemblability, maintainability, among others. However, DfX methodologies are undergoing the lack of real integration with 3D CAD systems. Their principles are currently applied downstream of the 3D modelling by following the well-known rules available from the literature and engineers’ know-how (tacit internal knowledge).This paper provides a method to formalize complex DfX engineering knowledge into explicit knowledge that can be reused for Advanced Engineering Informatics to aid designers and engineers in developing mechanical products. This research work wants to define a general method (ontology) able to couple DfX design guidelines (engineering knowledge) with geometrical product features of a product 3D model (engineering parametric data). A common layer for all DfX methods (horizontal) and dedicated layers for each DfX method (vertical) allow creating the suitable ontology for the systematic collection of the DfX rules considering each target. Moreover, the proposed framework is the first step for developing (future work) a software tool to assist engineers and designers during product development (3D CAD modelling).A design for assembly (DfA) case study shows how to collect assembly rules in the given framework. It demonstrates the applicability of the CAD-integrated DfX system in the mechanical design of a jig-crane. Several benefits are recognized: (i) systematic collection of DfA rules for informatics development, (ii) identification of assembly issues in the product development process, and (iii) reduction of effort and time during the design review.     

Endothelial Nitric Oxide Synthase (eNOS) 4b/a Gene Polymorphisms and Coronary Artery Disease: Evidence from a Meta-Analysis

A variety of studies have suggested that the 4b/a polymorphism in the endothelial nitric oxide synthase (eNOS) was associated with coronary artery disease (CAD) risk. However, the data remain conflicting. The aim of the present meta-analysis was to estimate the overall association between risk of CAD and eNOS 4b/a polymorphism. Case-control, cohort or cross-sectional studies evaluating the association between eNOS 4b/a polymorphism and CAD susceptibility were systematically identified in PubMed up to 31 October 2013. Pooled odds ratios (OR) and corresponding 95% confidence intervals (CIs) were calculated to assess the association in overall and subgroup analyses. A total of 10,617 cases and 8302 controls from 37 studies were included in the study. The results of overall analysis revealed significant positive associations between CAD risk and eNOS 4b/a polymorphism in homozygote comparisons (OR = 1.47, 95% CI = 1.16–1.87), heterozygote comparisons (OR = 1.14, 95% CI = 1.02–1.27) and dominant models (OR = 1.18, 95% CI = 1.06–1.33). In subgroup analyses, similar associations were identified in African individuals, as determined using population-based source subgroups and noted in small-and-moderate sample size subgroups (case sample size or control sample size <500). The current meta-analysis revealed that eNOS 4b/a polymorphisms could be a risk factor for developing CAD, particularly in African populations and population-based subgroups.     

基于三维CAD中望3D高效创建五金水槽模型

以前用二维CAD创建不锈钢盆体三维模型,不但过程复杂,而且异形盆体模型的中心线或中心点位置很难捕捉,特别是异形盆体中心和落水口的中心往往不能保证处于同一中心位置,总是有偏差。另外,还需要根据配套产品、制造工艺和市场需求反复修改,直至符合审核标准。中望3D作为一款拥有全球自主知识产权的工业级三维CAD／CAM软件,在三维模型设计方面更有优势,中心位置和自动捕捉更加方便精准。采用中望3D三维CAD软件,以中心线或中心点为基准便能轻松高效创建水槽模型。     

异形柱框架结构的分析与设计

结合钢筋混凝土异形柱框架结构的研究及应用现状，探讨了其结构分析的方法和构造等在设计中需要注意的若干问题，给出了几种结构分析软件的不同的分析方法，并比较了各自的计算精度，提出了合理的计算机辅助设计方法，可供设计时参考。     

VB在建筑物CAD软件开发中的应用

VB是一个深受欢迎的开发工具软件 ,而目前建筑物CAD的应用软件开发又十分重要。本文在利用VB进行建筑物CAD应用软件开发研究的基础上 ,总结了开发过程中的一些成功经验和实用技巧 ,对VB的应用以及建筑物CAD应用软件开发具有实际参考价值