Continuous design and redesign

This paper looks at the process of redesign (rather than designing from scratch). The process of writing the paper is itself used as an example of redesigning within the constraints of something that already exists.     

制图课程培养学生创新设计与实践能力的措施

针对工程制图课程如何培养学生工程图表达能力、创新设计能力及实践能力问题,提出既要重视基本理论,又要应用基本方法,以引导学生应用投影原理正确分析问题并发现有关规律。教学与工程实践结果证明了要注重基础理论的学习。提出了工程图表达应具备的基本思维方式。通过学生学习效果的调查,确定了教学难点与重点。     

Validation of engineering design alternative selection methods

The decision sciences have emerged over the past 300 years with contributions from many highly recognized individuals. Yet, by and large, these results have not been incorporated into engineering design decision methods, nor have these methods been validated. The result is that design decision methods commonly exhibit undesirable behaviors that are clearly evident when one knows what to look for. Indications of bad behavior are presented, and a framework for validation of engineering design alternative selection methods is suggested.     

Localization of soft tungsten contact fails with reliability implications by innovative reverse engineering techniques

Tungsten contacts mostly fail because of a defective bottom barrier which in turn may find its origin in technological problems with contact etch, barrier or tungsten deposition. Owing to the often unstable electrical properties of those contacts, detection in electrical test or non-destructive localization techniques is time-consuming or even unsuccessful. The reverse engineering techniques presented here supply 100% identification and localization of the failing contacts. They reveal a disturbed region under a barrier defect produced by the aggressive chemical reaction of fluorine radicals from WF₆ deposition with silicon to the gaseous SiF₄. The market contacts exceed the detection fails by far. Some failing contacts may slip through relaxed test conditions—the majority of them, though, still work and indicate a potential of reliability problems as could be demonstrated on chips failing the burn-in. Thus, an analysis and classification of the contacts at the wafer level in the presented way allows an identification and first step to estimation of reliability yield risks.     

Improved neural network model for reverse engineering

While conventional engineering transforms engineering concepts into real parts, in reverse engineering real parts are transformed into engineering models. The construction of a surface from three-dimensional (3D) measuring data points is an important problem in reverse engineering. This paper presents a reconstruction method for the sculptured surfaces from the 3D measuring data points. The surface reconstruction scheme is presented based on a neural network. The reconstruction of the existing surfaces is realized by training the network. A series of measuring points from existing sculptured surfaces is used as a training set. Once the neural network has been trained, it serves as a geometric model to generate all the points that are needed. However, the learning rate for the neural network is relatively slow, and the learning accuracy is often unacceptably low. In this paper, to improve the performance of the neural network, a pre-processor is proposed before the input layer. The pre-processor maps the input into the larger space by generating a set of linearly independent values. The effect of the pre-processor is to increase modelling accuracy, and reduce learning time. Based on this method, experimental results are given to show that the reconstructed surfaces are faithful to the original data points. The proposed scheme is useful for regular or irregular digitized data.     

Processing and characterization of innovative scaffolds for bone tissue engineering

A new protocol, based on a modified replication method, is proposed to obtain bioactive glass scaffolds. The main feature of these samples, named "shell scaffolds", is their external surface that, like a compact and porous shell, provides both high permeability to fluids and mechanical support. In this work, two different scaffolds were prepared using the following slurry components: 59 % water, 29 % 45S5 Bioglass(?) and 12 % polyvinylic binder and 51 % water, 34 % 45S5 Bioglass(?), 10 % polyvinylic binder and 5 % polyethylene. All the proposed samples were characterized by a widespread microporosity and an interconnected macroporosity, with a total porosity of 80 % vol. After immersion in a simulated body fluid (SBF), the scaffolds showed strong ability to develop hydroxyapatite, enhanced by the high specific surface of the porous systems. Moreover preliminary biological evaluations suggested a promising role of the shell scaffolds for applications in bone tissue regeneration. As regards the mechanical behaviour, the shell scaffolds could be easily handled without damages, due to their resistant external surface. More specifically, they possessed suitable mechanical properties for bone regeneration, as proved by compression tests performed before and after immersion in SBF.     

Design, production, and reverse engineering of two-octave antireflection coatings

We deal with design and production of optimal two-component antireflection (AR) coatings for an ultra broadband spectral range from 450 nm to 1800 nm. We demonstrate the whole design-production chain including design selection, choosing monitoring technique, coating production, and reverse engineering of the deposited coatings. At each step of this chain we provide thorough analysis on the basis of theoretical results and adequate computational manufacturing experiments. In order to produce the designed AR coatings we use magnetron sputtering deposition technique and accurate time monitoring.     

面向创新设计的多层次Web信息检索研究

提出了面向创新设计的多层次Web信息检索系统,它包括自然语言搜索、引导式搜索、关键词搜索、分类浏览和随机搜索五种搜索方式,主要功能是使设计人员从紧密到相对宽松的范围内进行资源检索(即从寻找相关设计知识到浏览无直接关系的信息),激发设计人员的创新思维,使之产生新的概念和新颖的设计思路。已经建立了基于以上原理的软件系统,该系统是计算机辅助产品创新设计的一个模块。     

Design model generation for reverse engineering using multi-sensors

Reverse engineering is the process of creating a design model and a manufacturing database for an existing part or prototype. The applications of reverse engineering are in redesigning of existing partstools or prototype parts where the CAD model of the part is not available. Reverse engineering, for the most part, is performed as an interactive process where the designer identifies the surface features from digitized data and then models the surfaces accordingly. This paper presents the algorithms and implementation results for a reverse engineering system which is intended to automatically create CAD representations of part prototypes. An integrated sensory system combining contact and non-contact sensors has been developed to digitize parts surfaces. The sensory system fuses data from machine vision and a coordinate measuring machine (CMM) in order to automatically digitize the part surface. Machine vision is used to capture the orthographic views of the part. The images of these orthographic views are processed and vectorized to create five views of the part in the form of an engineering drawing. The system utilizes the generated orthographic projections to automatically drive the CMM to capture a grid of point coordinates from the part surface. The CMM digitization process is guided by the segmentation provided from the orthographic views. The segmented data from the part surface is input to the surface modeling module of the system where parametric surfaces are fitted through the digitized points. The surfaces are then extended and intersected using the Hermite approximation method to develop the 3-D CAD model of the part. Accuracy and automation is achieved by combining global shape information obtained from part images with the accurate point data acquired by a CMM. Algorithms for surface segmentation, part digitization, surface extension, and surface intersection modeling are described in this paper.     

Multiplier methods for engineering optimization

Multiplier methods used to solve the constrained engineering optimization problem are described. These methods solve the problem by minimizing a sequence of unconstrained problems defined using the cost and constraint functions. The methods, proposed in 1969, have been determined to be quite robust, although not as efficient as other algorithms. They can be more effective for some engineering applications, such as optimum design and control of large scale dynamic systems. Since 1969 several modifications and extensions of the methods have been developed. Therefore, it is important to review the theory and computational procedures of these methods so that more efficient and effective ones can be developed for engineering applications. Recent methods that are similar to the multiplier methods are also discussed. These are continuous multiplier update, exact penalty and exponential penalty methods.     

Reliability principles, methodology and methods for lifetime design

The aim of integrated lifetime design is to predict and optimise the lifetime quality of the designed facility (building, bridge, tunnel, harbour, road, railway, airport, etc.). Lifetime quality means the capability of a facility or its structures to fulfil the requirements of its users, owners and society over its entire planning and design life (usually 50–100 years). The dictating phase for optimising the lifetime quality of a facility or structure is the planning and design phase, when the degree of freedom is high, and the cost of the phase is low. Generic limit state design aims to fulfil the generic requirements of lifetime quality. At the integrated planning and design stage, performance-based and generic structural limit states design includes the following three classes: (1) Static and dynamic modelling and design against mechanical loads; (2) Durability and service life modelling and design against degrading physical, chemical and biological loads; (3) Usability and service life modelling and design against obsolescence loads. As static and dynamic design are comprehensively dealt with in the literature and in practice, this report focuses on the lifetime safety factor method for durability design and obsolescence design. Main focus of this article is in durability design. On the obsolescence design are presented only a short summary and a number of references, because this design is not much connected to materials research.     

Automatic segmentation and approximation of digitized data for reverse engineering

Reverse engineering is the process of developing a computer-aided design (CAD) model and a manufacturing database for an existing object. This process is used in CAD modelling of part prototypes, in designing moulds and in automated inspection of parts with a complex surface. This paper reports on the automatic segmentation and approximation of three-dimensional digitized points for reverse engineering. Based on an innovation that uses the properties of a non-uniform rational B-spline (NURBS) or B-spline and makes ordered digitized points be control points directly to construct a NURBS or B-spline surface, which takes less computation time than traditional algorithms in calculating surface normals and curvatures at digitized points, an algorithm was developed for automatic segmentation and NURBS surfaces fitting for digitized points.     

An innovative tool for engineering good-quality holes in composite laminates

Drilling of polymer composites by means of traditional tools does cause a significant amount of damage to the surface. The forces generated during drilling are the major factors that exert an influence on hole quality. This makes the design and development of the drill geometries an area of paramount importance. Over the years, several tools have been developed and commercialized to minimize the damage induced by drilling. In this technical paper, we presented and discussed about an innovative tool point geometry that was designed, developed, and implemented for the purpose of investigating the drilling performance of composite laminates. The performance of the developed drill bit is compared with extensively used twist drill bit in reference to the drilling induced forces and damage. The input parameters considered are tool point geometry, speed, and feed. Results of this investigation reveal that both forces and damage are significantly reduced when holes are produced using the developed drill bit.     

Concepts,methods and tools in Kansei engineering

Trends in product development today indicate that customers will find it hard to distinguish between many products due to functional equivalency. Customers will, therefore, base their decisions on more subjective factors. Moreover, in the future, products will consist, to a higher grade, of a combination of a tangible and intangible part. Kansei Engineering is a tool translating customer's feelings into concrete product parameters and provides support for future product design. Presently, a total of six different types of Kansei Engineering are in use. The aim of this paper is to propose a framework in Kansei Engineering to facilitate the understanding of the different types of Kansei Engineering and to open Kansei Engineering for the integration of new tools. The new structure includes the choice of a product domain, which can be described from a physical and a semantic perspective as building a vector space in each. For the latter mentioned space, the Semantic Differential Method is used. In the next step, the two spaces are merged and a prediction model is built, connecting the Semantic Space and the Space of Product Properties together. The resulting prediction model has to be validated using different types of post-hoc tests.     

Automatic segmentation of digitized data for reverse engineering applications

Reverse engineering is the process of developing a Computer Aided Design (CAD)model and a manufacturing database for an existing part. This process is used in CAD modeling of part prototypes, in designing molds, and in automated inspection of parts with complex surfaces. The work reported in this paper is on the automatic segmentation of 3-Dimensional (3-D) digitized data captured by a laser scanner or a Coordinate Measuring Machine (CMM) for reverse engineering applications. Automatic surface segmentation of digitized data is achieved using a combination of region and edge based approaches. It is assumed that the part surface contains planar as well as curved surfaces that are embedded in a base surface. The part surface should be visible to a single scanning probe (21/2D object). Neural network algorithms are developed for surface segmentation and edge detection. A back propagation network is used to segment part surfaces into surface primitives which are homogenous in their intrinsic differential geometric properties. The method is based on the computation of Gaussian and mean curvatures of the surface. They are obtained by locally approximating the object surface using quadratic polynomials. The Gaussian and mean curvatures are used as input to the neural network which outputs an initial region-based segmentation in the form of a curvature sign map. An edge based segmentation is also performed using the partial derivatives of depth values. Here, the output of the Laplacian operator and the unit surface normal are computed and used as input to a Self-Organized Mapping (SOM) network. This network is used to find the edge points on the digitized data. The combination of the region based and the edge based approaches, segment the data into primitive surface regions. The uniqueness of our approach is in automatic calculation of the threshold level for segmentation, and on the adaptability of the method to various noise levels in the digitized data. The developed algorithms and sample results are described in the paper     

Product development for Chinese calligraphy using reverse engineering and rapid prototyping

Chinese calligraphy is considered to be one of the most beautiful and meaningful patterns in the world. Calligraphy is an art dating back to the earliest day of Chinese history, and widely practised throughout ancient China even to recent days. Owing to the passage of time, many old carvings of stamp characters have gradually faded. How to preserve these old Chinese cultural artifacts will be some crucial issues for today. Reverse engineering (RE) and rapid prototyping (RP) technology are considered effective tools for product development. This research combines RE, grey prediction theory in pattern processing, geometric modeling for constructing the characters of Chinese calligraphy and RP for model making. First, the written Chinese calligraphy is scanned by a scanner. By using image processing, the contours of the Chinese characters can be detected. The contours for the characters then turn out to be point data which can be easily processed in any computer aided design (CAD) software by using B-Spline curves to fit the points. An example is demonstrated by writing a Chinese compound word ‘the fortune and treasure are coming’ to show the process. Finally, a RP model is fabricated to show various applications for the products in Chinese calligraphy pattern. By this research, the gap between the Chinese calligraphy in handicraft and digital virtual design can be realized. More usefully, with this research the aesthetic aspects in the characters can be preserved.