Two-dimensional Computer-aided Design Research Articles

A Two-Dimensional Computer-Aided Design Study of Unclamped Inductive Switching in an Improved 4H-SiC VDMOSFET.

Due to its high thermal conductivity, high critical breakdown electric field, and high power, the silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) has been generally used in industry. In industrial applications, a common reliability problem in SiC MOSFET is avalanche failure. For applications in an avalanche environment, an improved, vertical, double-diffused MOSFET (VDMOSFET) device has been proposed. In this article, an unclamped inductive switching (UIS) test circuit has been built using the Mixed-Mode simulator in the TCAD simulation software, and the simulation results for UIS are introduced for a proposed SiC-power VDMOSFET by using Sentaurus TCAD simulation software. The simulation results imply that the improved VDMOSFET has realized a better UIS performance compared with the conventional VDMOSFET with a buffer layer (B-VDMOSFET) in the same conditions. Meanwhile, at room temperature, the modified VDMOSFET has a smaller on-resistance (Ron,sp) than B-VDMOSFET. This study can provide a reference for SiC VDMOSFET in scenarios which have high avalanche reliability requirements.

Creating digital twins from computer drawings and laser scans: a comparison

Building information models offer significant advantages in managing existing buildings and infrastructure. If no such ‘digital twins’ exist, they can be generated from two-dimensional computer-aided design drawings or from laser scanning photogrammetry. This paper starts by describing and comparing the two methods of model generation. It then reports on a study where both methods were used to model a university building complex in Turkey. The results are compared and discussed, highlighting their respective advantages and disadvantages. It is concluded that the ideal solution is a combination of elements of both methods.

An interactive sketch-based CAD interface realizing geometrical and topological editing across multiple objects based on fuzzy logic

With the widespread use of digital pen tablets and touch displays, sketch-based interactive computer-aided design (CAD) user interfaces have attracted considerable attention. In an existing interface called the Sketch Input Tracer (SKIT), however, the editing operation performed via an over-sketching stroke can target only a single geometric object at any given time. To overcome this limitation, in this study, we propose a new general-purpose sketch-based interface developed for use in two-dimensional CAD systems. In the proposed interface, a sketch-based editing operation can simultaneously modify the geometry and topology of multiple geometric objects via over-sketching. The interface was developed based on the fuzzy logic-based strategy of SKIT. With this interface, a user can draw in a creative manner; for example, they can begin with a rough sketch and progressively create a detailed design through repeated over-sketches. The results of experiments conducted demonstrate that experts can control the proposed interactive drawing interface and beginners can habituate to controlling it.

Pressure and velocity behavior of an incompressible flow through the reduction of a pipe using CFD

In this research the methodology for the simulation by computational fluid dynamics (CFD- Computational Fluid Dynamics) of an incompressible flow is proposed by using Solidworks® Flow Simulation, measuring the behavior of pressure and velocity in reductions of the cross-sectional area of the pipe, making decrements of 0.02 m in the input area of five different models. There are three main parts to this methodology; two-dimensional computer-aided CAD (Computer-Aided Design) design of the pipeline, pipeline modeling, and CFD simulation. The simulation results showed an increase of between 10 and 14% of the fluid velocity, and a pressure loss of 13 to 75% in the area with the smallest area of the pipe for each 0.02 m reduction in diameter, derived from the energy conservation principle of ideal fluids.

Prototype Design of Rainwater Harvesting and Solar Irrigation System for Small-Scale Farm

The current irrigation system at Taman Tanaman Dapur that used by the Faculty of Bioresources and Food Industry (FBIM) is operated manually, and the water source is directly from Syarikat Air Terengganu (SATU). The cost incurred to maintain the current system is expensive therefore, the UniSZA fund for maintenance purpose. By observing these factors, there is an opportunity to improve the irrigation system by utilising the available natural resources in the form of sun and rain, respectively, as a source of energy and water. Thus, the objectives of this project are to design and validate the prototype of rainwater harvesting and solar irrigation system for small scale farm use. By utilising the prototype, it is possible to take advantage of the available natural resources resulting in a technological advancement that optimises the energy usage producing a cost-effective, efficient irrigation system. The prototype design was carried out using a two-dimensional computer-aided design software, AutoCAD. Furthermore, the prototype development was carried out and validated with several readily-available types of equipment in the laboratory as well as equipment that could be obtained by local farmers or individuals. As a result, after going through phases of prototype creations, from the proof of concept, through mock-up testing, and pre-production, it has been well-function as designated. The value of Gross Irrigation Requirement (GIR) for this study was 308.22 mm/month while the minimum requirement of power production from the solar panel output was 0.552 kWh. More improvement can be made for further development of the prototype by integrating with other technologies such as attach it with moisture sensor and timer for the optimum condition.

ABGS: A System for the Automatic Generation of Building Information Models from Two-Dimensional CAD Drawings

Building Information Modeling (BIM) refers to 3D-based digital modeling of buildings and infrastructure for efficient design, construction, and management. Governments have recognized and encouraged BIM as a primary method for enabling advanced construction technologies. However, BIM is not universally employed in industries, and most designers still use Computer-Aided Design (CAD) drawings, which have been used for several decades. This is because the initial costs for setting up a BIM work environment and the maintenance costs involved in using BIM software are substantially high. With this motivation, we propose a novel software system that automatically generates BIM models from two-dimensional (2D) CAD drawings. This is highly significant because only 2D CAD drawings are available for most of the existing buildings. Notably, such buildings can benefit from the BIM technology using our low-cost conversion system. One of the common problems in existing methods is possible loss of information that may occur during the process of conversion from CAD to BIM because they mainly focus on creating 3D geometric models for BIM by using only floor plans. The proposed method has an advantage of generating BIM that contains property information in addition to the 3D models by analyzing floor plans and other member lists in the input design drawings together. Experimental results show that our method can quickly and accurately generate BIM models from 2D CAD drawings.

수력 현대화 개·대체 시 스파이럴 케이스와 흡출관 형상에 따른 모델수차 설계 적용사례 연구

Recently, turbines operating in hydro power plants are required to undergo renovation and modernization due to their age exceeding 30 years. In the process of renovation or modernization, a performance test of the scaled-down model is necessary to verify the performance of the real-size model. This model test method, with criteria that is similar to that of a real turbine, is the most economical and important method. Furthermore, the shapes of the runner and guide vane can be modified or replaced easily. However, during the process of modernization, the components with the spiral casing and draft tube are impossible to repair or replace because of the buried ground. Thus, in this study, numerical analysis is conducted to investigate the hydraulic performance based on the difference between the two-dimensional computer-aided design (CAD) shape and the real three-dimensional scan shape of the spiral casing and draft tube.

A New Virtual Reality for 3D Technology in the Utility Industry

Will traditional two-dimensional computer-aided design processes someday feel as archaic as T-squares and compasses? It might happen sooner rather than later, thanks to swift advances in 3D technology.

TCAD Based Assessment and Performance Optimization of ZnO/Si Heterojunction Based Thin-film Solar Cell

In this paper 2D numerical simulation of n-ZnO/i-ZnO/p-Si p-i-n heterojunction solar cell using TCAD has been presented. In this work the design and performance optimization of p-i-n heterojunction solar cell using two-dimensional computer aided design (TCAD) tool has been presented. The device has been simulated and analyzed with respect to the I-V characteristics of the device in dark and illuminated condition. Further figure of merits like short circuit current (Isc), Open circuit Voltage (Voc), fill factor (FF), internal and external quantum efficiency (IQE &EQE), maximum power generated (Pmax) and conversion efficiency of the designed solar cell has been extracted. The I-V characteristics of the device and performance in terms of power conversion efficiency has been optimized for the proposed structure of solar cell with respect to doping concentration in n-ZnO and i-region thickness of the device. The simulation results indicate that the n-ZnO/i-ZnO/p-Si p-i-n heterojunction solar cell could be a good candidate for solar cells.

Identity Orientation, Social Exchange, and Information Technology Use in Interorganizational Collaborations

Advances in information technologies (IT) are creating unprecedented opportunities for interorganizational collaboration, particularly in large-scale distributed projects. The use of advanced IT in such projects can foster new forms of social exchange among organizations and change the way organizations view themselves in the context of their relationships. Despite a wealth of research on IT use, social exchange, and organizational identity, little is known about how new IT and the enactment of related IT affordances within interorganizational contexts enable social exchanges and organizational identity orientations. To address this gap, we conduct multiple case studies that describe the changing use of two-dimensional computer-aided design technology and new three-dimensional modeling technologies by a leading metal fabrication company in the architecture, engineering, and construction industry. The case studies demonstrate that changes in the company’s IT and the enactment of related IT affordances within variable interorganizational contexts enable new forms of social exchanges. These exchanges, in turn, provide the context for the rearticulation of the company’s identity orientation. Based on these insights, we formulate a theoretical model to delineate the relationships between IT use, IT affordances, social exchanges, and identity orientation. We conclude by outlining the implications of our study and suggesting possible avenues for future research.

Influence of absorber doping in a-SiC:H/a-Si:H/a-SiGe:H solar cells

This work deals with the design evaluation and influence of absorber doping for a-Si:H/a-SiC:H/a-SiGe:H based thin-film solar cells using a two-dimensional computer aided design (TCAD) tool. Various physical parameters of the layered structure, such as doping and thickness of the absorber layer, have been studied. For reliable device simulation with realistic predictability, the device performance is evaluated by implementing necessary models (e.g., surface recombinations, thermionic field emission tunneling model for carrier transport at the heterojunction, Schokley—Read Hall recombination model, Auger recombination model, bandgap narrowing effects, doping and temperature dependent mobility model and using Fermi—Dirac statistics). A single absorber with a graded design gives an efficiency of 10.1% for 800 nm thick multiband absorption. Similarly, a tandem design shows an efficiency of 10.4% with a total absorber of thickness of 800 nm at a bandgap of 1.75 eV and 1.0 eV for the top a-Si and bottom a-SiGe component cells. A moderate n-doping in the absorber helps to improve the efficiency while p doping in the absorber degrades efficiency due to a decrease in the VOC (and fill factor) of the device.

A reversible watermarking scheme for two-dimensional CAD engineering graphics based on improved difference expansion

Difference expansion is widely used in reversible watermarking for raster images, but it cannot be applied to data with low correlation, due to its large distortion. In this paper, an improvement is made to difference expansion technology to make it suitable for two-dimensional (2D) computer-aided design (CAD) engineering graphics. Based on improved difference expansion (IDE), a reversible watermarking scheme for 2D CAD engineering graphics is proposed. First, all vertices of the 2D CAD engineering graphics are extracted, and then the relative coordinates of these vertices are calculated. Finally, the encrypted watermark is embedded into the scale factor of the relative coordinates by using IDE technology. Experimental results show that the proposed scheme has a large capacity, good imperceptibility, and is robust against operations such as transformation, rotation, and equal scaling.

Healthcare—Tides of Change

Strong currents are exerting a force on the future of healthcare capital construction; they are impacting every discipline from planners to architects, engineers, finance groups, and owners. These currents constitute a sea change that affects every phase of a capital project, from initial master planning and approval to the postoccupancy evaluation. These tidal forces are affecting projects no matter where they are in their life cycle and they include new economic realities, uncertainty about healthcare reform, corporate awareness of green building and sustainability, innovative financing, new delivery models, and even the way architects produce drawings. Any one of these realities would present a challenge, but with the convergence of so many profound changes, the industry has been stretched and shaken to its core. Metrics and benchmarking are among the tools healthcare leaders are developing to help manage costs and risks, and to chart a course through these uncertain and challenging times.Healthcare costs have soared, putting healthcare reform high on the national agenda. Part of these cost increases are attributable to escalating construction costs and the increased volume of healthcare projects that started in 2003 and were a dominant force until 2008, when the economy went from full speed ahead to a full stop overnight. Problems with the money supply have interrupted many privately funded projects. In an attempt to control cost and risk, owners have expanded their stable of delivery options to include costplus, shared-risk, and incentive programs; integrated project delivery; design build; and lean construction. There is an emerging consensus that reducing a company's carbon footprint and building in a sustainable manner are corporate responsibilities. Alternative financing and tax credits are being used to lock in escalating energy costs. Architects are transitioning from twodimensional computer-aided design and drafting to three-dimensional modeling or building information models, which demand new skills and a new partnership with contractors. These major shifts at the core of the industry are occurring just as the Baby Boomers are beginning to retire. With the Boomers' departure, years of accumulated knowledge and expertise will be lost. Any of these changes alone represents a major shift in practice, but all of these changes together have created immense risks and opportunities that will require constant re-evaluation, personal change, a new level of cooperation, and hard work to meet the healthcare needs of the future. …

Semi-Automatic 3D Reconstruction of Urban Areas Using Epipolar Geometry and Template Matching

This paper describes a new technique for obtaining the volumetric description of large urban areas. This technique uses automatic procedures coupled with some interactive procedures for the three-dimensional (3D) reconstruction of urban areas from airborne stereo-pair images whose output is virtual reality modeling language (VRML) or Drawing Exchange Format (DXF). The main challenge is to compute the relevant information, such as building's height and volume, roof's description, and texture, algorithmically in a time- and cost-efficient manner. The algorithm requires some initial calibration input and is able to compute building characteristics using the stereo pair of aerial images and two-dimensional computer-aided design and digital elevation models of the same area. No knowledge of the camera pose or its intrinsic parameters is needed. The authors use epipolar geometry, homography computation and automatic feature extraction in this approach. They have solved the feature correspondence problem in the stereo pair by using template matching. Directions for future work are discussed.

Using Site-Based Techniques to Evolve the Product Development Process in Manufacturing Industries

Many manufacturing industries, especially small to medium-sized companies, are in the process of exploring the move from two-dimensional computer-aided design (CAD) technologies to three-dimensional CAD tools interfaced with product data management (PDM) systems. For many companies, their current organizational structure is not well suited to fully leverage the capabilities of new CAD/PDM technology. This paper explores the author's experiences working in the residential furniture industry, helping companies successfully integrate CAD/PDM systems into their engineering and manufacturing operations. Of particular focus was the role user-centered, site-based techniques played in helping one company with this integration process. Both current and future scenarios based on an in-depth analysis of the product developed process were generated and used to help guide an implementation plan for a new CAD/PDM system.

A student oriented CAD system in APL

This paper describes a two-dimensional computer-aided design tutorial system (CADETS) modelled after Unigraphics I. Written in APL, a 3279 colour graphics terminal is used as a graphics input as well as output device. The screen is divided into five windows. The main, and the largest, window is used for graphics; the others are used for user communication. Menus are used extensively to generate, modify and manipulate the display. Within CADETS, there are currently eleven ways to create a point, thirteen ways to create a line segment, ten ways to specify a circular arc, several functions to generate common geometric objects such as triangles, rectangles, polygons, conics and ten fonts to write labels. Once created, the user may pick the geometric entities in the current model for inquiry, transformation or deletion through a series of selection menus. Manipulation of geometric entities is facilitated by transformation functions such as translation, scaling, rotation, and mirroring. Options to move, copy or duplicate the transformed entities are available. Geometric models created by the user may be stored as either TSIO or VSPC data sets. The user may retrieve, inquire or change the data set names of the models at will. The power of CADETS is further enhanced by the introduction of layers. This facility enables the user to view and draw each individual layer independently or to view selected layers simultaneously. The system has been used by several users including high school students who were unaware of even the existence of APL. The system requires minimal investment on hardware as well as software compared to sophisticated expensive systems, yet provides tools for teaching several fundamental CAD techniques.