Computer-aided Design Environment Research Articles

A new boundary-based morphological model

Mathematical morphology addresses the problem of describing shapes in an n-dimensional space using the concepts of set theory. A series of standardized morphological operations are defined, and they are applied to the shapes to transform them using another shape called the structuring element.In an industrial environment, the process of manufacturing a piece is based on the manipulation of a primitive object via contact with a tool that transforms the object progressively to obtain the desired design. The analogy with the morphological operation of erosion is obvious. Nevertheless, few references about the relation between the morphological operations and the process of design and manufacturing can be found. The non-deterministic nature of classic mathematical morphology makes it very difficult to adapt their basic operations to the dynamics of concepts such as the ordered trajectory.A new geometric model is presented, inspired by the classic morphological paradigm, which can define objects and apply morphological operations that transform these objects. The model specializes in classic morphological operations, providing them with the determinism inherent in dynamic processes that require an order of application, as is the case for designing and manufacturing objects in professional computer-aided design and manufacturing (CAD/CAM) environments. The operators are boundary-based so that only the points in the frontier are handled. As a consequence, the process is more efficient and more suitable for use in CAD/CAM systems.

Information Technology in Environment Digital Design Based on CAD

Spatial structure of landscape ecology is composed by different ecosystems, the interaction function and dynamics. It is to the entire landscape as the research object, emphasizing the interaction between the protection and management of large areas of population ecology, management of environmental resources and human activities spatial heterogeneity of the maintenance and development, ecosystem and its components on the landscape impact. This paper presents several models of several computer-aided digital design environments, and the depth of the concrete application of various models.

CONSTRUCTION 3D BIM-BASED KNOWLEDGE MANAGEMENT SYSTEM: A CASE STUDY

Knowledge management (KM) is the organization, creation, sharing and flow of knowledge within organizations. Knowledge can be shared and reused among involved engineers and experts to improve a construction process and reduce the time and cost of solving problems. This paper proposes a new and practical methodology to capture and represent construction project knowledge by using a Building Information Modeling (BIM) approach. Using BIM approach, users can make visual knowledge management in the 3D Computer-aided Design (CAD) environment. This study addresses the application of knowledge management in the construction phase of construction projects and proposes a Construction BIM-based Knowledge Management (CBIMKM) system for general contractors. The CBIMKM is then applied in selected case studies of a construction building project in Taiwan to verify our proposed methodology and demonstrate the effectiveness of sharing knowledge in the 3D environment. By applying the BIM approach, all participants in a project can share and reuse explicit and tacit knowledge through the 3D CAD-based knowledge map. The combined results demonstrate that the CBIMKM system can be used as a visual 3D-based knowledge management platform by utilizing the BIM approach and web technology.

Integration and application of feature recognition and mould manufacturing planning navigating process

Plastic injection mould manufacturing is diverse and complex. Traditional mould manufacturing planning often relied on experience and techniques. Therefore, in order not to affect the operation or even cause some loss of the enterprises, geometry information of computer-aided design (CAD) should be converted into manufacturing information of computer-aided process planning (CAPP) and CAM for automatic feature recognition to shorten the lead time. This study is the secondary development in a CAD environment creating a network plastic injection mould manufacturing navigating system and CAD/CAPP for integration and application. As part design is feature-based, each processing step can be regarded as a feature. By applying the hybrid recognition technology of the graph-based approach, the rule-based approach and hint-based approach in the analysis of part feature appearances, it can automatically categorise all the manufacturing features of the part and convert them into corresponding processes. The CAPP developed in this study can convert the part manufacturing features into corresponding processes and plan the part process sequence according to the process priority constraint relations. As proved by the case studies, the use of CAPP in this study can reduce planning time by 87%. It can provide users with a reference regarding process sequence, and speed up the part planning progress. Coupled with the mould manufacturing navigating process, it can achieve automatic design and manufacturing.

An Integrated Approach Supporting Design, Simulation, and Production Engineering of Connection Techniques in Automotive Body-in-white Development

Today's automotive industry is characterized by increasingly shorter development times. This fact takes place in almost all areas of car development. The presented work is concerned with the automated support in BIW-design (body-in-white design). Presented is a method to support the design engineers in creating and processing data within the applied computer-aided design (CAD) environment. Through the implemented algorithm, a continuous process is provided, which closes the gap between the different design and simulation processes which are necessary for the preparation and verification of body-in-white connection technologies. Moreover, the presented method is used as a connection to computer-aided manufacturing (CAM). This linking also works in the reverse direction, so that changes in the course of simulation or manufacturing engineering can be responded in the CAD process with significantly reduced effort.

MODELING HUMAN TISSUES: AN EFFICIENT INTEGRATED METHODOLOGY

Geometric models of human body organs are obtained from imaging techniques like computed tomography (CT) and magnetic resonance image (MRI) that oallow an accurate visualization of the inner body, thus providing relevant information about their its structure and pathologies. Next, these models are used to generate surface and volumetric meshes, which can be used further for visualization, measurement, biomechanical simulation, rapid prototyping and prosthesis design. However, going from geometric models to numerical models is not an easy task, being necessary to apply image-processing techniques to solve the complexity of human tissues and to get more simplified geometric models, thus reducing the complexity of the subsequent numerical analysis. In this work, an integrated and efficient methodology to obtain models of soft tissues like gray and white matter of brain and hard tissues like jaw and spine bones is proposed. The methodology is based on image-processing algorithms chosen according to some characteristics of the tissue: type, intensity profiles and boundaries quality. First, low-quality images are improved by using enhancement algorithms to reduce image noise and to increase structures contrast. Then, hybrid segmentation for tissue identification is applied through a multi-stage approach. Finally, the obtained models are resampled and exported in formats readable by computer aided design (CAD) tools. In CAD environments, this data is used to generate discrete models using finite element methed (FEM) or other numerical methods like the boundary element method (BEM). Results have shown that the proposed methodology is useful and versatile to obtain accurate geometric models that can be used in several clinical cases to obtain relevant quantitative and qualitative information.

Circuit Description and Design Flow of Superconducting SFQ Logic Circuits

Superconducting Single-Flux-Quantum (SFQ) devices have been paid much attention as alternative devices for digital circuits, because of their high switching speed and low power consumption. For large-scale circuit design, the role of computer-aided design environment is significant. As the characteristics of the SFQ devices are different from conventional devices, a new design environment is required. In this paper, we propose a new timing-aware circuit description method which can be used for SFQ circuit design. Based on the description and the dedicated algorithms we have been developing for SFQ logic circuit design, we propose an integrated design flow for SFQ logic circuits. We have designed a circuit using our developed design tools along with the design flow and demonstrated the correct operation. key words: single-flux-quantum circuit, design methodology, circuit description, logic design, layout design, design verification

Incorporation of high recyclability material selection in computer aided design

Manufacturing are now under increasing pressure of tighten environmental legislation to preserve natural resources. Product design, as a part of manufacturing activities, has to be more concern to deliver product specification with reduced environmental impact. Design for Recycling (DFR) is one of the promising approaches in prolonging material utilization of a product in the early stage of design. DFR focus on harmonizing product design with the recycling practices in order to minimize the loss of valuable materials and preventing unnecessary waste streams at the end of product’s life. In turn, it limits the usage of natural resources.To implement DFR, designers are faced with the challenge of compromising different design objectives such as cost, functional or technical requirements and product’s recyclability performance. This paper attempts to propose an intelligent approach that could facilitate designers to make an easy and quick recyclability assessment as well as selecting recyclable materials integrated with computer aided design. In this paper, the use of fuzzy inference system and genetic algorithm is proposed to optimize the multi-objective problem in the selection of recyclable materials. Case study on the actual conceptual design using computer aided design environment is demonstrated and showing that the proposed method successfully can be applied concurrently during product design. Comparison of proposed method with Sustainability Express Solid Work is also presented. The proposed method can assist product designers to design a high recyclability product without ignoring technical perspectives.

The application of ubiquitous multimodal synchronous data capture in CAD

Design is an interactive and iterative process where the designer’s skills and knowledge are fused with emotive rationales aided by design tools. A design solution is thus influenced by the designer’s creativity, experience and emotional perception. Consequently, there is a need within computer aided design (CAD) research for ubiquitous tools to capture the affective states of engineers during design activities to further understand the product design process.This paper proposes a generic framework for ubiquitous multimodal synchronous data capture, based around the capture of CAD system activities, to monitor and log a variety of inputs, interactions, biophysical data and design solutions with a view to providing meta and chronological performance data for post design task analysis. The framework has been employed in two use cases namely, a CAD station activity and a collaborative design review. The results of these trials validated the architecture and use of the ubiquitous data capture approach demonstrating the practical application of time-phased data capture, analysis and the subsequent output of metadata in CAD environments providing a new perspective on, and a new way of investigating CAD-based design activities.This research also extrapolates the framework’s usefulness into future CAD and PLM systems by arguing why and how they need to adopt such ubiquitous platforms. It also subjectively points to potential opportunities and issues that might arise when implementing the ubiquitous multimodal metadata architecture in a real-life environment.

Precision Manufacturing Process of Parts Realized by FDM Rapid Prototyping

Rapid Prototyping (RP) can be defined as a group of techniques used to quickly fabricate a scale model of a part or assembly using three-dimensional computer aided design (CAD) data. What is commonly considered to be the first RP technique, Stereolithography, was developed by 3D Systems of Valencia, CA, USA. In this contribution are presented basic characteristics and problems in area of technology of Rapid Prototyping with use of Fused Deposition Modelling. It belongs to methods of precision model creation based on geometry obtained from CAD environment. Chapters are focused on optimization of FDM technology preparation process with aim of maximal precision of the parts. There also is algorithm that leads to selection of suitable settings for these problems. There are outputs in form of graph and tables accumulating information directly affecting precision aspects of manufacturing.

The effect of type of restoration on the stress field developed in terminal abutments with severely reduced periodontal support and coronal structure

Periodontally compromised teeth (PCT) that serve as terminal abutments (TAs) are often challenging depending on the post-and-core treatment, the type of partial fixed dental prosthesis (PFDP), and the periodontal support. The purpose of this study was to investigate the biomechanical impact of 3 types of PFDP supported by cast post-and-cores on PCT serving as terminal abutments. A 3-dimensional (3D) model of a human mandible was fabricated by using computed tomography (CT) images and parameterized in a computer-aided design (CAD) environment as follows: Right premolar preparation geometries were designed. The second premolar was assembled with 7-mm or 10-mm cast post-and-core models. Both premolar-models were designed to support single, splinted, or 1-unit cantilever splinted crowns. In each situation, their periodontium geometries were designed to be reduced by 10%, 50%, and 70%. All models were imported into a 3D finite element analysis (FEA) environment and loaded; von Mises stress values and distribution patterns were evaluated. Insertion of the post primarily affected the apical areas of both the root and post; the type of PFDP and periodontal support mainly affected stress distribution. In patients with a normal periodontium, splinting the teeth did not contribute to their stress relief. By extending the post length, a stressful area close to the apex of the post was developed. Splinting mitigated the stress field of the coronal part of the 50% PCT (up to 98.9%); the 30% PCT experienced a substantial decrease (up to 215.9%) in stress in the radical part as well. The increase in the length of the post produced negligible stress-related differences in the apical part of the 50% PCT (0.2% to 2.6%). The use of the 7-mm post effectively relieved the radical part of the splinted 30% PCT. The magnitude of the stress on the radical part of post-restored PCT was considerably increased in the presence of a cantilever. Splinted crowns supported by a 7-mm cast post-and-core are a favorable biomechanical approach for the restoration of PCT with severe loss of coronal structure. The use of a cantilever greatly aggravates the biomechanical response, especially of post-restored PCT.

Optimal design of the solar tracker used for a photovoltaic string

This paper approaches the optimal design of the mono-axial tracking system used for a string of photovoltaic (PV) modules. The tracking mechanism is designed in a CAD (Computer Aided Design) environment (SolidWorks), the solid model being then transferred in the dynamic analysis and optimization environment (adams/View). The control system is designed with adams/Controls and matlab/Simulink, in mechatronic concept, by integrating the mechanical device and the control system at the virtual prototype level. The control method is based on a single-open-loop model with PID (Proportional-Integral-Derivative) controller, having as input the daily angle of the PV string. The output from the control system (i.e., the input in the mechanical device model) is the motor torque developed by the rotary actuator that drives the system. The tracking program has been developed by using an empirical model of the solar irradiation, obtaining the optimal angular field for the daily motion, the number of motion steps, and the actuating time. The optimization purpose is to minimize the tracking error, the design objective's value being the root mean square during simulation. The specific parameters of the PID controller are used as design variables in the optimization process. The investigation strategy is based on a design of experiments technique, obtaining the appropriate regression function. Finally, the physical prototype is developed and tested in real environment, the experimental results being used to validate the virtual prototyping-based simulation.

A method for reverse engineering of material microstructure for heterogeneous CAD

Integration of material composition, microstructure, and mechanical properties with geometry information enables design and analysis of materials and products in a computer-aided design (CAD) environment. In this paper, we propose a method for the construction of material models from microstructure images, that can be integrated into a heterogeneous CAD representation. The method utilizes Radon and wavelet transforms to compute a surfacelet representation. A novel feature recognition method was developed to identify microstructure features, including embedded fibers and grain boundaries, from the surfacelet representation. The models and methods were demonstrated with examples of synthetic and engineered polymer nanocomposites, a metal alloy, and a medical dataset of human feet.

Assessment and comparison of immersive virtual assembly training system

This paper presents the assessment and comparison of a virtual assembly training system for the first Saudi Arabian car prototype fender assembly. An assessment study was conducted to compare three training scenarios: Traditional Engineering, Computer Aided Design Environment, and Immersive Virtual Reality (IVR). Fifteen students from King Saud University were randomly assigned to the different training conditions. After that transfer of training to the actual assembly was evaluated. Performance measures used to assess transfer of training include time to complete task and number of frustration points during task. Furthermore, experiments were conducted to evaluate the effect of number of trainings in IVR environment on user’s performance while performing the virtual assembly. The results of study suggest that the participants of IVR training condition performed better than the other two conditions. Also, it was seen that the participants with more number of training within IVR performed better while doing virtual assembly.

GUIDING TEMPLATES FOR PEDICLE SCREWS INSERTION: A PRELIMINARY STUDY

Fixation of pedicle screws necessitates high surgical skill and a great deal of experience in order to avoid injuries to nerves and vessels. In this study, we develop a computer-aided procedure to produce personalized drill guides that are designed to enhance the safety of pedicle screw insertion in the spinal region. Based on a patient's computed tomography (CT) data, it is possible to design personalized drill guides in a self-developed computer-aided design environment. These guides are designed to fit on the surface of vertebrae in a unique position in order to indicate both the preplanned drill path and the drilling length into the pedicle. A rapid prototyping device is used as a three-dimensional printer to produce the shape of reference areas on bone surfaces. Postoperative CT scans are obtained, and the accuracy of the pedicle screws is measured. By using customized templates in a case study, the guiding templates are shown to be highly accurate and to provide great assistance for planning and executing surgeries. The accuracy of screw placement is confirmed with postoperative CT scanning. The average angle of the drilling paths between planning and postsurgery is approximately 1.05°. The average deviation of entry points of drilling paths between planning and postsurgery is approximately 2.99 mm. The performance proves a high degree of accuracy in comparison with conventional techniques achieved through fluoroscopy. However, a significant number of clinical cases is needed to validate the feasibility of this method. The device is proven to be reliable and compatible; in the future, surgeons can use the guiding templates to complete more complicated cases such as those involving idiopathic scoliosis and cervical complications.

Modeling and simulation of UPFC using PSCAD/EMTDC

This paper proposes to model and simulate a unified power flow controller (UPFC) in power system computer aided design and electromagnetic transient direct current (PSCAD/EMTDC) environment. The series converter of the UPFC controls the transmission line real/reactive power flow and the shunt converter of the UPFC controls the UPFC bus voltage/shunt reactive power and the DC link capacitor voltage. The real power demand of the series converter is supplied by the shunt converter of the UPFC via the DC link capacitor. The control of transmission line reactive power flow leads to excessive voltage excursion of the UPFC bus voltage. In this proposed work, we have considered two system cases. The first case is to cause a sudden increase in the system load. The second case is to introduce a transient fault in the system. In both cases, excessive bus voltage excursions occur. A UPFC is modeled and designed to reduce these bus voltage excursions, and also proper coordination between the series and shunt converter controllers of the UPFC is maintained to limit the collapse of DC capacitor voltage. PSCAD/EMTDC software is utilized to design and simulate the model.

Development and Evaluation of a Virtual Assembly Trainer

This paper discusses the development and evaluation of a virtual assembly training system for the first Saudi Arabian car prototype (Gazal-1) fender assembly. An evaluation study was conducted to compare 3 training scenarios: Traditional Engineering (TE), Computer Aided Design Environment (CADE), and immersive virtual reality (IVR). 15 students from King Saud University were randomly assigned to the different training conditions. After that, transfer of training to the actual assembly was evaluated. Performance measures used to assess transfer of training include time to complete task and number of frustration points during task. The results of the evaluation study suggest that the participants of IVR training condition performed better than the other two conditions. Therefore, virtual assembly simulation using virtual reality systems might be useful for training operators who will be conducting assembly operations.

A physical design tool for carbon nanotube field-effect transistor circuits

In this article, we present a graphical Computer-Aided Design (CAD) environment for the design, analysis, and layout of Carbon NanoTube (CNT) Field-Effect Transistor (CNFET) circuits. This work is motivated by the fact that such a tool currently does not exist in the public domain for researchers. Our tool has been integrated within Electric a very powerful, yet free CAD system for custom design of Integrated Circuits (ICs). The tool supports CNFET schematic and layout entry, rule checking, and HSpice/VerilogA netlist generation. We provide users with a customizable CNFET technology library with the ability to specify λ-based design rules. We showcase the capabilities of our tool by demonstrating the design of a large CNFET standard cell and components library. Meanwhile, HSPICE simulations also have been presented for cell library characterization. We hope that the availability of this tool will invigorate the CAD community to explore novel ideas in CNFET circuit design.

A system for rapid creation and assessment of conceptual large vehicle designs using immersive virtual reality

Currently, new product concepts are often evaluated by developing detailed virtual part and assembly models with traditional computer aided design (CAD) tools followed by appropriate analyses (e.g., finite element analysis, computational fluid dynamics, etc.). The creation of these models and analyses are tremendously time consuming. If a number of different conceptual configurations have been determined, it may not be possible to model and analyze each of them due to the complexity of these evaluation processes. Thus, promising concepts might be eliminated based solely on insufficient time and resources for assessment. In addition, the virtual models and analyses performed are usually of much higher detail and accuracy than what is needed for such early assessment. By eliminating the time-consuming complexity of a CAD environment and incorporating qualitative assessment tools, engineers could spend more time evaluating concepts that may have been previously abandoned due to time constraints. To address these issues, the Advanced Systems Design Suite (ASDS), was created. The ASDS incorporates a PC user interface with an immersive virtual reality (VR) environment to ease the creation and assessment of conceptual design prototypes individually or collaboratively in an immersive VR environment. Assessment tools incorporate metamodeling approximations and immersive visualization to evaluate the feasibility of each concept. In this paper, the ASDS system and interface along with specifically designed immersive VR assessment tools such as state saving and dynamic viewpoint creation are presented for conceptual large vehicle design. A test case example of redesigning an airplane is presented to explore the feasibility of the proposed system.

An interactive, visual approach to developing and applying parametric three-dimensional spatial grammars

AbstractSpatial grammars are rule based, generative systems for the specification of formal languages. Set and shape grammar formulations of spatial grammars enable the definition of spatial design languages and the creation of alternative designs. Since the introduction of the underlying formalism, they have been successfully applied to different domains including visual arts, architecture, and engineering. Although many spatial grammars exist on paper, only a few, limited spatial grammar systems have been computationally implemented to date; this is especially true for three-dimensional (3-D) systems. Most spatial grammars are hard-coded, that is, once implemented, the vocabulary and rules cannot be changed without reprogramming. This article presents a new approach and prototype implementation for a 3-D spatial grammar interpreter that enables interactive, visual development and application of grammar rules. The method is based on a set grammar that uses a set of parameterized primitives and includes the definition of nonparametric and parametric rules, as well as their automatic application. A method for the automatic matching of the left hand side of a rule in a current working shape, including defining parametric relations, is outlined. A prototype implementation is presented and used to illustrate the approach through three examples: the “kindergarten grammar,” vehicle wheel rims, and cylinder cooling fins. This approach puts the creation and use of 3-D spatial grammars on a more general level and supports designers with facilitated definition and application of their own rules in a familiar computer-aided design environment without requiring programming.