Computer-aided Designs Research Articles

A Study on the Application of Design Thinking Strategy to Form Generation System

There are two kinds of thinking strategy, which are vertical thinking and lateral thinking [1]. Nowadays, there are few computer-aided designs using design thinking strategy. Most computer aided designs combine the consumer's emotional and pattern matching. Base on this reason, this study's purpose is the application of design thinking strategy to computer-aided design, and use the Model of Two Paths which proposed by Tseng & Chang [2], and combined parametric modeling of derivatives design. The authors hope in the future, the computer systems can assist the designer in thinking. Currently, the study found the process of parametric modeling form generation that changes the spatial relation which is similar to Jumping thinking of lateral thinking. The shape evolution between different vocabulary is similar to Triggering thinking of lateral thinking [2].

Pharmacokinetics and pharmacodynamics – is there anything new?

Pharmacokinetics and pharmacodynamics – is there anything new?

Preparation of poly(ε-caprolactone)-based tissue engineering scaffolds by stereolithography

A photocrosslinkable poly(ε-caprolactone) (PCL)-based resin was developed and applied using stereolithography. No additional solvents were required during the structure preparation process. Three-armed PCL oligomers of varying molecular weights were synthesized, functionalized with methacrylic anhydride, and photocrosslinked, resulting in high gel content networks. Stereolithography was used to build designed porous scaffolds using the resin containing PCL macromer, Irgacure 369 photoinitiator, inhibitor and dye. A suitable resin viscosity was obtained by heating the resin during the curing process. The scaffolds precisely matched the computer-aided designs, with no observable material shrinkage. The average porosity was 70.5 ± 0.8%, and the average pore size was 465 μm. The pore network was highly interconnected. The photocrosslinkable, biodegradable PCL resin is well suited for the solvent-free fabrication of tissue engineering scaffolds by stereolithography.

Computer-aided optimal designs for improving neural network generalization

In this article we propose a new insight into the field of feed-forward neural network modeling. We considered the framework of the nonlinear regression models to construct computer-aided D-optimal designs for this class of neural models. These designs can be seen as a particular case of active learning. Classical algorithms are used to construct local approximate and local exact D-optimal designs. We observed that the so-called generalization of a neural network (the equivalent term, "predictive ability", is more familiar to statisticians) is improved when the D-efficiency of the chosen "learning set design" increases. We thus showed that the D-efficiency criterion can be the basis for a better strategy for the neural network learning phase than the standard uniform random strategy encountered in this field. Our proposition is based on two possible strategies: a One-Step Strategy or a Full Sequential Strategy. Intensive Monte Carlo simulations with an academic example show that the D-optimal "learning set design" strategies proposed lead to a substantial improvement in the use of neural network models.

Study of Impact-Induced Mechanical Effects in Cell Direct Writing Using Smooth Particle Hydrodynamic Method

Biomaterial direct-write technologies have been receiving more and more attention as rapid prototyping innovations in the area of tissue engineering, regenerative medicine, and biosensor∕actuator fabrication based on computer-aided designs. However, cell damage due to the mechanical impact during cell direct writing has been observed and is a possible hurdle for broad applications of fragile cell direct writing. The objective of this study is to investigate the impact-induced cell mechanical loading profile in cell landing in terms of stress, acceleration, and maximum shear strain component during cell direct writing using a mesh-free smooth particle hydrodynamic method. Such cell mechanical loading profile information can be used to understand and predict possible impact-induced cell damage. It is found that the cell membrane usually undergoes a relatively severe deformation and the cell mechanical loading profile is dependent on the cell droplet initial velocity and the substrate coating thickness. Two important impact processes may occur during cell direct writing: the first impact between the cell droplet and the substrate coating and the second impact between the cell and the substrate. It is concluded that the impact-induced cell damage depends not only on the magnitudes of stress, acceleration, and∕or shear strain but also the loading history that a cell experiences.

Methods of expert estimations at the automated planning of untypical constructions

The article is devoted to the questions of analysis of existing computer-aided designs and questions of development of new information technologies of planning on the basis using of united informatively-logical model of object.

SubIslands: the probabilistic match assignment algorithm for subcircuit recognition

The recognition of subcircuit instances in a larger circuit is widely used in the simulation, verification, and testing of integrated circuit computer-aided designs. Subcircuit recognition (SR) can be stated as a problem of finding images of a small model bipartite graph (BG) corresponding to a subcircuit in a large object BG corresponding to a circuit. The best-known SR algorithms are based on the search-oriented subgraph isomorphism methods. Unfortunately, these methods may require a long runtime for large and highly symmetrical circuits. The authors develop a new high-performance probabilistic recognition method for solving the SR problem. This method combines: 1) the graduated assignment matching technique; 2) two well-known concepts from pattern recognition theory, namely, the error propagation and the delayed decision making; and 3) an efficient probabilistic BG labeling algorithm. In contrast to the search-based algorithms, the new recognition method solves the SR problem as an optimization task and, as a consequence, allows extremely fast simultaneous finding of subcircuit images. The experimental results show that this approach recognizes all the subcircuit instances orders of magnitude faster than the search-oriented algorithms.

On the use of a simplified model for switched reluctance motors

The paper presents a simple model for the nonlinear magnetization characteristics of a switched reluctance motor (SRM). The flux linkage is given as a continuous mathematical expression, depending on the phase current and rotor position. This expression can then be differentiated or integrated easily without computer use; it enables finding a mathematical formula for the instantaneous torque of each phase. The model is valuable for computer-aided designs, especially for sizing and initial estimates, where accuracy can be traded with time saving. The model was implemented to verify its degree of accuracy. The simulation program has the ability to calculate numerous parameters that can be very useful for quick estimates of the efficiency for a particular SRM drive or even when choosing a particular motor.

On the Use of a Simplified Model for Switched Reluctance Motors

This paper presents a simple model for the nonlinear magnetization characteristics of a switched reluctance motor (SRM). The flux linkage is given as a continuous mathematical expression depending on the phase current and rotor position. This expression can then be differentiated or integrated easily without computer use; it allows finding a mathematical formula for the instantaneous torque of each phase. The model is valuable for computer-aided designs, especially for sizing and initial estimates where accuracy can be traded with time saving. The model was implemented to verify its degree of accuracy. The simulation program has the ability to calculate numerous parameters that can be very useful for quick estimates of the efficiency for a particular SRM drive or even to choose a particular motor.

Computer-Aided Molecular Designs of the Enediyne Model Compounds

Computer-Aided Molecular Designs of the Enediyne Model Compounds

Need I repeat myself? Non-repeating computer-aided designs for printed textiles

Historically, repeating patterns have been a technological and commercial restraint of mass-produced printed textiles. However, we have a natural desire to find, or make, patterns and order in many aspects of our visual lives, making many repeating patterns pleasing to the eye. Now that the technology has the capability to produce lengths of fabric directly from computer to ink-jet printer, both the technological and commercial restraints are being lifted. This paper addresses the possibilities for non-repeating patterns on fabric, investigating both the practicalities and design considerations through the use of examples created in my own practical research. As the designer and programmer of the software I have been able to produce designs which look intriguingly like they may repeat, but in fact, never do.

A simple model for switched reluctance motors

This letter presents a simple model of nonlinear magnetization characteristics of a switched reluctance motor (SRM). The flux linkage is given as a continuous function of phase current and rotor position. This allows a mathematical formula to be found for the instantaneous torque. The model is valuable for computer-aided designs, especially for sizing and initial estimates where accuracy can be traded with time saving. The model was implemented to verify its degree of accuracy. The simulation program has the ability to calculate numerous parameters that can be very useful for quick estimates of the efficiency of a particular SRM drive or for motor selection.

Characterization of a single-step microstrip discontinuity in a substrate using the finite-difference time-domain method

A single-step microstrip discontinuity in a substrate is characterized using the finite-difference time-domain (FDTD) method, and an equivalent circuit model has been developed. The microstrip discontinuity newly introduced in this paper has a substrate thickness change in the longitudinal direction with a uniform strip width. The discontinuity has applications in patch antenna feed design and interconnections between microwave circuit modules. The simulation results are compared with those computed by HFSS to show good agreement. An equivalent circuit developed from the FDTD results, which is accurate within 2.4% in magnitudes of S11 and S21, can be applied for computer-aided designs. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 245–248, 2000.

Modelling of a high-frequency operated fluorescent lamp in an electronic ballast environment

The authors describe the dynamic modelling of a high-frequency operated fluorescent lamp in an electronic ballast environment. The model inherently includes the negative resistive characteristic, allows the study of electronic ballast design using series resonant converters, and can provide useful information for the optimisation of the electronic ballast design. The fluorescent lamp model for high-frequency frequency operation has been developed and implemented. Predictions for the lamp system operation generally agree very well with measurements obtained from a 33 kHz electronic ballast-fluorescent lamp system. The use of the model for the designing the ballast components is illustrated. This model is simple and can be employed in existing simulation packages for computer-aided electronic ballast designs.

Hemodynamic simulations and computer-aided designs of graft-artery junctions.

Severe occlusion of graft-artery junctions due to restenosis, e.g., excessive tissue overgrowth and renewed plaque formation, may occur within a few months or years after bypass surgery. Our hypothesis is that nonuniform hemodynamics, represented by large sustained wall shear stress gradients, trigger abnormal biological processes leading to rapid restenosis and hence early graft failure. In turn, this problem may be significantly mitigated by designing graft-artery bypass configurations for which the wall shear stress gradient (WSSG) is approximately zero and hence nearly uniform hemodynamics are achieved. Focusing on the distal end of several femoral artery bypass junctions, a validated finite volume code has been used to compute the transient three-dimensional velocity vector fields and its first and second surface derivatives in order to test the idea. Specifically, it is shown that the Taylor patch, which generates higher patency rates than standard end-to-side anastomoses, exhibits lower WSSG levels than standard configurations, and that further geometric design improvements reduce the WSSG in magnitude and local extent even more.

特集：プリント配線板設計と電磁特性 ３． 「ＣＡＤ設計」 レイアウトＣＡＤの基本的手法

特集：プリント配線板設計と電磁特性 ３． 「ＣＡＤ設計」 レイアウトＣＡＤの基本的手法

Circular short backfire antenna modeling

The first three-dimensional analysis of a short backfire antenna (SBA) is described using the vector-mode-matching method. The computation is efficient for a model that uses only the first harmonic, cos phi , and that deforms the path of numerical integration. This model is useful for SBA computer-aided designs. A larger directivity than previously reported is obtained with the aid of this model. The theoretical predictions of the radiation pattern yield better agreement than previous methods when compared with measurements performed on a prototype.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Annealing behavior of Al–Y alloy film for interconnection conductor in microelectronic devices

Progress in patterning technologies and computer-aided circuit designs have brought us to the threshold of submicron dimensions in the fabrication of very large scale integrated circuits. For metallization at submicron dimensions, several requirements must be satisfied. In the present study we have prepared pure Al and Al–Y alloy films with different yttrium concentration by electron-beam evaporation and evaluated several annealing characteristics for the Al–Y/(100)Si system by using a transmission electron microscope, scanning electron microscope, and measuring the electrical resistivity. We found that in the Al–0.7 wt % (0.2 at. %) Y alloy film annealed above 300 °C the electrical resistivity decreases to a value similar to that of a pure Al film, that is, 2.9 μΩ cm, and the same concentration of yttrium is also sufficient to minimize the generation and growth of annealing hillocks. These results are explained by the compositional and microstructural changes occurring in the Al–Y/(100)Si system.

Mixture designs for product improvement studies

Many products are mixtures of several components (ingredient). Characteristics of the products such as the strength of steel, the efficacy of a chemical pesticide, or the viscosity of a liquid detergent, depend only on the relative proportions of the components in the mixture. Studying changes in a product' properties caused by varying the ingredient proportions is the objective of performing mixture experiments. The inherent restriction that the sum of the component proportions equal unity creates different design strategies than are usually employed with independent factors where factorial arrangements are quite common. Experimental designs for exploring the entire mixture simplex region as well as for exploring only a subregion of the simplex are presented. In those cases where four or more components are considered and a subregion is to be investigated, computer-aided designs are the rule rather than the exception. Design criterion based on the properties (variance and bias) of the prediction equation...

ガウス写像による工学的曲面分類とその応用

In the computer-aided designs for castings or forgings, we encounter many complex shaped surfaces, which are difficult to create or evaluate even with use of modern CAD systems. Further, structural or mechanical engineers are annoyed with lack of methodology to evaluate adaptiveness of generated surfaces; conventional graphic tools are unuseful in the above cases.In the present study, one proposes an engineering method to deal with curved surfaces appearing in the practical designs. Based on the differential geometry and computational processings, the proposed approach employs an indicator for evaluation of curved surfaces, and gauss image is applied to represent the distribution of gauss curvetures. Through rough comparison of generated gauss images, one can see differences of curved surfaces. Furthermore, using the present approach, one can estimate the graphical accuracy of approximate triangular development method for both developable and undevelopable surfaces.