Showing papers on "Design strategy published in 2004"

Multiparadigm modeling in embedded systems design

Abstract: Embedded electronic systems for monitoring and control of technical processes (electronic control unit-ECU) are systems comprised of heterogeneous components (hardware, software, sensors, actuators, power electronics), thus making high demands on their development. Describing different aspects and views of the whole system, subsystem, or component requires according modeling paradigms for requirements specification, design, hardware implementation, software code generation, verification, integration, and testing. The first part of the paper surveys characteristic ECU features and describes a design strategy and the related technology, bringing out the necessity of multiparadigm modeling. Examples from automotive ECU applications are used throughout the paper. With respect to the problem that currently available tools provide insufficient support, integration strategies for multiparadigm modeling based on multiple tools are surveyed in the second part, concluding with examples from our own research activities.

Risk Metric for Multi‐Objective Design of Naval Ships

Abstract: The DoD Risk Management Guide requires risk assessment of acquisition performance, cost, and schedule through the identification, subsequent analysis and prioritization of adverse program events based on their probability and consequences. This type of risk assessment is very important in concept exploration and design when considering new technologies, unique processes, and novel concepts. Uncertainty associated with the design process itself and the definition and selection of specific design alternatives can also have a significant impact on performance, cost, and schedule risk. Inherent, statistical and modeling uncertainty and uncertainty because of human error, must be considered in the design process, but uncertainty analysis requires a more detailed and computationally intensive probabilistic approach. It is most appropriate for post-exploration design optimization, after specific cost and performance goals and thresholds have been set to maximize the probability of achieving these goals. In this paper, a two-stage concept design strategy is proposed that uses a multi-objective optimization and simplified risk event approach for concept exploration and a more rigorous multi-disciplinary optimization with uncertainty for concept development. Concept exploration identifies nondominated design concepts and establishes the optimum relationship between effectiveness, cost, and risk given a broad selection of technologies and design alternatives. In this context, non-dominated (N-D) refers to designs with the maximum effectiveness for a given cost and level of risk. This is a global optimization design problem that considers a wide range of performance, cost and risk possibilities. Risk is defined using a separate objective attribute, an overall measure of risk (OMOR), which specifically addresses the high-risk events associated with the selection of new technologies, processes, and concepts. With this perspective, decision-makers may establish ratio-nal requirements, select technologies, narrow the design space, and establish a non-dominated concept baseline design or set of designs. Once these early decisions are made, concept development and the remaining design phases add detail, refine requirements and reduce risk. Optimization continues into concept development, but a single objective optimization based on uncertainty analysis is used, maximizing the probability of success (POS) of satisfying cost and effectiveness thresholds and other constraints established in concept exploration. The methodology and a simple application of the multi-objective optimization and risk event approach are described in this paper.

Design Strategy and Constraints for Medium-Power Lead-Alloy–Cooled Actinide Burners

Abstract: We outline the strategy and constraints adopted for the design of medium-power lead-alloy–cooled actinide-burning reactors that strive for a lower cost than accelerator-driven systems and for robus...

How system designers think: a study of design thinking in human factors engineering.

Abstract: The paper presents a descriptive study of design thinking in human factors engineering. The objective of the study is to analyse the role of interpretation in design thinking and the role of design practice in guiding interpretation. The study involved 10 system designers undertaking the allocation of cognitive functions in three production planning and control task scenarios. Allocation decisions were recorded and verbal protocols of the design process were collected to elicit the subjects' thought processes. Verbal protocol analysis showed that subjects carried out the design of cognitive task allocation as a problem of applying a selected automation technology from their initial design deliberations. This design strategy stands in contrast to the predominant view of system design that stipulates that user requirements should be thoroughly analysed prior to making any decisions about technology. Theoretical frameworks from design research and ontological design showed that the system design process may be better understood by recognizing the role of design hypotheses in system design, as well as the diverse interactions between interpretation and practice, means and ends, and design practice and the designer's pre-understanding which shape the design process. Ways to balance the bias exerted on the design process were discussed.

Aspectualize and conquer in architectural design

Abstract: This paper describes architectural design processes from a cognitive science/artificial intelligence perspective. It characterizes the design task in terms of classical AI problem solving attributes. As architectural design specifications leave many relevant dimensions unspecified, it is a fascinating question how these dimensions are fixed during the design process. We identify general strategies to cope with the complex space of spatial design by considering cognitive approaches to understanding and problem solving. The AI "divide and conquer" problem solving strategy is adapted to the common design strategy of reducing problem complexity by focusing on different aspects of the design problem at a time. Examples from design principles in architecture are presented. 1. The Designer's Dilemma The domain of creative design in general and the domain of architectural spatial design in particular pose special challenges for the modeling of the processes involved. We will briefly outline some of the characteristics of the problem space that architects are confronted with. We will use concepts and terminology from computer science/artificial intelligence to describe the architectural domain. In the article, we analyze the design problem from a knowledge representation and reasoning point of view. For this purpose, various abstract spaces are introduced to characterize the design task and the design process. In this framework, cognitive principles are considered and applied to principles from architectural design.

Manual and automatic design for UMTS networks

Abstract: This paper describes manual and automatic design strategies of UMTS networks. The design aims at adjusting antenna parameters: antenna pattern, tilt and azimuth angles, as well as the common channels' transmitted power to improve the network performance in terms of coverage, capacity, quality of service and service continuity. The manual design strategy is based on an expert system that analyzes different quality criteria of the network and suggests the designer the most effective parameter modifications. The automatic design strategy is based on a Genetic Algorithm that orchestrates the design process. Two optimisation models are considered: the first one uses constant load hypotheses in the network evaluation; the second one takes into account inhomogeneous traffic distribution and utilizes accurate modelling of basic UMTS quantities such as power, load and interference. Detailed examples of network optimization illustrate the effectiveness of the design strategies.

On-line and off-line control design in power electronics and drives using genetic algorithms

Abstract: This paper describes an automated control system design strategy for power electronics and drives. The design method employs a genetic algorithm (GA) based optimization routine that can be implemented off-line and on-line. A suitable user definable fitness function assesses the performance of several control parameters, and selects which values will evolve to the next generation. Evolution over many generations evaluates a wide range of controller structures and values, and ultimately determines which one best achieves the control goals. Simulation and experimental results carried out using as applications an active filter and an induction motor drive show that the method produces an excellent controller design, but equally importantly, the design is carried out with very little user interaction. As such the design method is attractive to commercial manufacturers, as it can significantly reduce commissioning times.

Daylighting Prediction Software: Comparative Analysis and Application

Abstract: Daylighting is a beneficial design strategy since i t may provide energy savings and contribute to a more sustainable design. In recent studies, daylighting has also been shown to increase staff and student productivity and to decrease absenteeism. The consulting engineer is often faced with the di lemma of how to design a daylighted building. What tools are available to predict the amount of daylighting? What are the design limitations and parameters? How much time is required? How does the data compare to the “real world”? The purpose of this paper is to answer these que stions and provide useful information for the design of daylighted areas with the assistance of software-based simulation. A survey was made of the available software programs for the calibrated modeling of light scattered in enclosed spaces. These software packages used algorithms based on either total radiosity (flux transfer) computations or physically accurate ray tracing. A summary of this survey along with the selection criteria used in selecting a software program are presented.

Animating personalised networking in a student apartment complex through participatory design

Abstract: This paper describes the research design of an ongoing case study in an apartment complex comprising approximately 160 intemational students in Brisbane, Australia. The objective of the study involves the design and development of an online community network to facilitate the creation and growth of a sustainable residential neighbourhood community. The study is informed by the PAD methodology which combines principles of participatory design with sociocultural animation. Preliminary research findings led to a new design strategy which takes Wellman's theory of networked individualism into account. The new community building strategy allows for the diversity and individualism of tenants by working towards providing easy and convenient ways for tenants to identify birds of a feather and to conduct personalised networking. What may emerge from this process is an intricate web of social networks that span the anonymous void of the apartment complex itself, a web of "urban tribes".

MOS current mode logic: design, optimization, and variability

Abstract: An automated optimization-based design strategy for 2-level MOS current mode logic (MCML) circuits is proposed to overcome the complexities of the design process. The methodology minimizes the power dissipation while satisfying the performance criteria. Moreover, environmental and process variations modeling are included in the design strategy. The impact of these variations on MCML performance as technology scales is also presented. In addition, design tips based on analytic formulation are presented for MCML designers. The proposed methodology is tested on several benchmarks belonging to optical communication and high-speed microprocessor applications built in a CMOS 0.18/spl mu/m process, at which the average error is within 7% between our formulation and HSPICE.

Design and optimization of MOS current mode logic for parameter variations

Abstract: An automated optimization-based design strategy is proposed for single-level MOS Current Mode Logic (MCML) gates to overcome the complexities of the gate design procedure. The proposed design methodology determines the values of the design variables that achieve the minimum power dissipation point while attaining the required performance. The proposed design methodology has the advantage of speed, accuracy, and ability to include a large number of parameters in the design problem. Moreover, a formulation for the impact of parameter variations on the MCML gate performance is presented. The proposed strategy is used to design two popular circuits, namely; the ring oscillator and clock distribution network drivers with an average error from the required performance within 8%. The dependence of the gate parameters on parameter variations is used with the design methodology to redesign the same circuits while considering parameter variations. Furthermore, the impact of parameter variations as the technology scales down is investigated.

Suspension dynamics and design optimization of a high speed railway vehicle

Abstract: The design of suspension systems for high-speed railway vehicles involves the simultaneous consideration of those requirements as suspension packaging, ride quality, stability, and cost. A design strategy is presented in this paper that enables an optimal design with respect to these competing requirements. The design strategy consists of four steps including the development of a lumped parameter vehicle model, the determination of vehicle parameters, the formulation of a design objective, and the minimization of the objective to optimize key suspension parameters. The design objective captures vehicle requirements including ride quality, suspension packaging, and wheel/rail holding. Power spectral densities (PSDs) are computed for the vertical vehicle body acceleration, suspension travel and dynamic wheel/rail interaction. The design objective function is calculated based on these PSDs and minimized to yield an optimum. An example suspension design is proposed that improves vehicle ride quality and wheel/rail holding without sacrificing other requirements.

Web-Based Mechanical Engineering Design Education Environment Simulating Design Firms

Abstract: Mechanical design education focuses on teaching students with fundamental design theory and methodology. Educators systematically introduce design theories, processes, and tools to help students solve design problems. Companies and professional organizations expect that students will be equipped with basic understanding of the engineering practice, and be able to effectively perform independently and in a team environment. Senior capstone design courses, particularly with industry sponsored projects, are widely used to satisfy both education and professional needs of students. This paper presents an education system, which can further facilitate students to acquire design skills in a real-time collaborative, and practical environment. The web-based system helps student teams to: (1) specify the design process for their team projects, (2) organize and distribute tasks among different team members to simulate industry design environment, and (3) get instantaneous access to models, analysis, etc. related to their design. The developed web-based system also contains a knowledge-base that provides students with instructions to setup the design process for projects, and to perform different design tasks. A virtual design organization is created in the system, which is managed by students. In this paper different components of the web-based design education system are presented.Copyright © 2004 by ASME

Sequential Experimental Design Strategy for Optimal Batch Profiles Using Hybrid Function Approximations

Abstract: An underlying experimental design algorithm for obtaining optimal batch profiles in a sequential fashion is addressed. The proposed design technique, composed of the hybrid function approximation a...

Lightweight Design of Crashworthy Carbody Structure for High-speed Passenger Train Based on Optimization

Abstract: A design strategy based on optimization is developed in this paper to solve the comprehensive design problem for high-speed railway passenger vehicles.It tries to design the lightweight car body structure with multi-level optimization and analyses,which may satisfy the requirements of both elastic deformations in all ordinary conditions and plastic deformations in crash events.A concept model of railway vehicle and high-speed passenger vehicle were studied to execute the design procedure suggested by using linear and non-linear finite element techniques.The results of numerical analyses has proved its feasibility and effectiveness.

A comparative study of performance of the design strategic groups and design strategies

Abstract: The results generated from a questionnaire survey conducted in the period of 2002 to 2003 have shown that Taiwanese home appliance firms' product design strategy can be classified into passive response, aggressive response, and R&D focus groups according to characteristics classified by factor analysis and cluster analysis. Differences in issues related to the design strategy adopted by each group are highlighted from case studies. Performance in new product development differs among strategic groups. Overall, the aggressive response group performs the best, followed by the R&D focus group, and finally the passive response group. Some relationships between the design strategy related issues adopted by each strategic group and performance have been found after comparisons between them.

A Simulation-Based Vehicle Design Strategy for Acquisition and Requirements Validation

Abstract: To acquire a new fleet of vehicles, Army decisionmakers must consider many conflicting requirements including the needs of users, the vehicle’s life cycle implications in terms of reliability, maintainability, and survivability, and the design and production capabilities of the contractor. Army decision-makers choose appropriate vehicle characteristic targets to maximize military objectives within an acquisition budget. This budgetary constraint is especially important when costly new technology is considered. Once product characteristic targets are decided, contractors bid for the design and production contract. This approach is limited if the military does not directly account for the contractors’ design capabilities when targeting specific vehicle characteristics. This limitation can result in the inability of the winning contractor to meet some or all of the product targets, leading to costly delays in product delivery and potentially sub-optimal performance. An analytical tool that captures the tradeoffs among military objectives and models the design capabilities of suppliers can aid decision-makers during the acquisition process. This article builds on the Analytical Target Cascading methodology by developing extensions of Analytical Target Setting to facilitate requirements validation, developing acquisition decision models, and examining a case study for dual-use technology. These methods use comprehensive vehicle simulation models, which represent the contractor’s design capabilities, to drive vehicle target setting decisions. Conclusions will be drawn from previous research applied in the commercial sector to show how the military can take advantage of formalizing the links between engineering design decisions and non-technical decisions to reduce risk and improve quality of the final product.

Modeling, Analysis, and Uncertainty Quantification of a Lightweight Torpedo Design

Abstract: In designing a lightweight torpedo, multiple performance criteria from many disciplines, including structures, acoustics, controls, and hydrodynamics, have to be satisfied in order to maintain a high probability of success for the mission. These criteria could conflict with each other as design requirements, in which case the final design will be the configuration that minimizes conflicts. Performance criteria depend on various design parameters that constitute the configuration of the torpedo and these are usually assigned deterministic values. However, in reality, the parameters would exhibit variations, and thus the design criteria could potentially violate the feasible design space. Therefore, this paper presents a robust torpedo design strategy that provides the designer insight into the safety of the final configuration, subject to variations in design parameters. In this paper a torpedo is modeled using finite elements and its static and dynamic characteristics are analyzed subject to variations in the design parameters structural problem. In this paper, a torpedo is modeled using finite elements and its static and dynamic characteristics are analyzed subject to variations in the design parameters.

Probabilistic Strategy Based Dynamic System Design Using Bond Graph and Genetic Algorithm

Abstract: This paper proposes a probability-encoded genotype serving as a design strategy (designer) to generate design topologies using bond graphs. This strategy evolves by applying a genetic algorithm (GA) for exploration of a multi-domain design space in a topologically openended manner, finding configurations efficiently. Probability-based decision making encoded in the designer is applied at each topology generation stage. Instead of searching topology and parameters simultaneously like in genetic programming, our approach completes the design process in two sequential steps: 1) topology generation and 2) parameter optimization. By this means, the mathematical model generated from the topology can be efficiently tuned by optimizing the parameters independent of the configuration. A circuit filter design problem is used as a case study.

Realities in interdisciplinary systems design

Abstract: It is obvious that the integration of different technologies into interdisciplinary systems cannot be treated as their simple summing but as a way of compensating their mutual weaknesses and amplifying the synergy of their integration. A detailed definition of concepts of positive and negative synergy with examples from both categories is given. It is pointed out that the ever-growing competition on the markets has caused the need for radical cuts in product development time and has forced to change the approach to the design for reliability and quality of the non-safely-critical systems. As a result, negative synergy-based infant mortality risks are growing. It is also shown that synergy and quality indicators are in strong correlation forming a platform for competitive reliability. Special attention is paid to the clarification of interrelations between human and technical aspects in the design process. It is shown that human faults and mistakes can also be treated in synergy context. Further a search for synergy-friendly design strategy is provided and it is shown that the Design Structure Matrixes technology is a suitable basis for this purpose. Finally, some case studies of successful synergy-based integration of allied technologies are described. In the conclusion it is arrived at the truth that the synergy-based approach to the interdisciplinary systems design is a possible way to create a complete picture of all realities in design process.

Design of an aseptic process simulation

Abstract: The authors suggest a design strategy for an aseptic process simulation that focuses on the basic repeating unit of the process, establishing alert and action criteria for the unit itself, and using worst-case simulations to establish routine operational parameters for the manufacturing process.

A cfd based software system for the automathic design of radial inflow turbines

Abstract: The paper presents a design strategy for radial turbines based on a software architecture developed by the authors. All the computational tools are available at source code level and integrated to form an automatic design methodology. Links to interdisciplinary analysis and methods (structural analysis or CAD design) are provided in order to complete the design strategy for industrial components. The computational algorithms range from 1D design/analysis methods to a Navier-Stokes solver for three-dimensional compressible viscous flows in rotating passages. In order to provide a preliminary search for the design variables in a wide design space, an optimization procedure has been introduced. This is based on a one-dimensional design method and a genetic algorithm. The application of the software infrastructure to the design of a radial turbine for an industrial microgasturbine is described.