Modern Design Methodologies Research Articles

Comparison of Block-Shear and Whitmore Section Methods for Load Rating Existing Steel Truss Gusset Plate Connections

Many transportation agencies are now evaluating and rating their inventory of steel truss bridge gusset plate connections after the collapse of the I35W Bridge in Minneapolis. Modern design methodologies are being used to evaluate inventory gusset plate connections that were designed using allowable stress methods. One such implementation is evaluation of gusset plates using block shear, an approach that was developed well after many of the nation's truss bridges were designed. Vintage designs commonly used the Whitmore section to proportion gusset plate connections. Differences between rating outcomes from block-shear analysis at strength conditions with designs that employed allowable stresses on the Whitmore section method were identified and expected outcomes for rating of gusset plate connections are proposed. Examples are shown to highlight the similarities and differences in these two approaches to assist rating engineers in implementation and expected variabilities on the outcomes based on connection geometric proportions and material properties. DOI: 10.1061/ASCEBE.1943-5592.0000048 CE Database subject headings: Plates; Steel; Trusses; Bridge failures; Connections; Loading rates; Minnesota. Author keywords: Gusset plates; Steel truss bridges; Bridge rating; Whitmore section; Block shear.

Fine Control of Local Whitespace in Placement

In modern design methodologies, a large fraction of chip area during placement is left unused by standard cells and allocated as “whitespace.” This is done for a variety of reasons including the need for subsequent buffer insertion, as a means to ensure routability, signal integrity, and low coupling capacitance between wires, and to improve yield through DFM optimizations. To this end, layout constraints often require a certain minimum fraction of whitespace in each region of the chip. Our work introduces several techniques for allocation of whitespace in global, detail, and incremental placement. Our experiments show how to efficiently improve wirelength by reallocating whitespace in legal placements at the large scale. Additionally, for the first time in the literature, we empirically demonstrate high-precision control of whitespace in designs with macros and obstacles. Our techniques consistently improve the quality of whitespace allocation of top-down as well as analytical placement methods and achieve low penalties on designs from the ISPD 2006 placement contest with minimal interconnect increase.

Glass melting furnaces designing energy-efficient bottle glass furnaces

It was shown that developing an energy-efficient design for a bottle glass furnace implies the use of modern design methodology. It is necessary to include mathematical modeling before the technical design stage in the structure of the traditional stages of work on a furnace design. The boundary conditions of modeling must reflect the conjugate character of external and internal heat exchange and the hydrodynamics of the melting tank.

Supporting decision making in risk management through an evidence‐based information systems project risk checklist

PurposeThis paper aims to present a study of Information Systems project risk management aimed at identifying a risk ontology and checklist that will enable decision making and mitigation strategy planning in information system (IS) development in the public sector. This sector is an ideal research field in risk management practices, due to the visibility that failure of IS/IT projects has acquired as a consequence of the duty of accountability that characterises it.Design/methodology/approachThe study is based on a qualitative approach anchored on a critical literature review, leading to the development of an analytical framework, followed by a thorough case‐study survey.FindingsA project risk ontology was derived from the analysis of ten case‐studies in the UK, USA and New Zealand and was divided into five main categories: pre‐project, customer, project management, technological issues, and development methodology. The analysis found that a considerable number of risk factors are incurred before the start of the formal project and pre‐determine the future of the project and create predictable risks that can be avoided.Research limitations/implicationsThis paper has focused on the pre‐implementation and implementation phases of IT/IS projects and further research into IS post‐implementation is required.Originality/valueThe proposed ontology is designed to fit in real life systems development cycles and is aimed at supporting risk assessment and control. The findings suggest that risk thinking should start early in the project and not, as many modern design and development methodologies propose, solely as part of the development process itself.

Gyung-Jin Park: Analytic methods for design practice

The recent book Analytic Methods for Design Practice by Professor Gyung-Jin Park of the Department of Mechanical Engineering, Hanyang University, Republic of Korea, covers several theories and methods of modern design methodology in the area of practical design and optimization of engineering products and processes. The term ‘Analytic Methods’ in the title of the book is to be understood as design methods that are based on rigorous theories with a definite form. Thus, in contrast to the traditional approach where the design process is only based on the designer’s intuition and experience, the design methodologies presented in this book are entirely founded on design logic that can be expressed in an abstract way. Professor Park’s book is strongly recommended as a very timely and important text on modern engineering design practice. Thus, the book does not only cover methodologies for the stage of detailed design, in particular optimization methods, but also gives a very thorough presentation of analytic methods for the preceding stage of conceptual design. The latter are methods of axiomatic design that may enhance the creativity in the conceptual design stage and considerably improve the product to be designed. The material of the book is organized into 10 chapters with the following titles.

Hybrid CAD Modeling Theory and Method in Reverse Engineering

RE is the generic name of a series of technical methods that convert physical parts into engineering concepts and CAD model. It has been an important branch of modern design methodology. With the development of computer and graphic design, RE has already no longer met the simple imitation products, but product innovation based on physical parts. In order to redesign the CAD model constructed by RE method and then support product innovation, hybrid CAD modeling method and some related key techniques are studied in this paper. Combining conventional design and RE, Hybrid CAD modeling method extracts features, constraints, and design intent from measured data for parametric redesign and eventually completes CAD model.

Using a Design Repository to Drive Concept Generation

This paper describes how a design repository can be used as a concept generation tool by drawing upon archived function-based design knowledge. Modern design methodologies include several types of activities to formally generate design concepts. Typical concept generation methods range from open-ended creative brainstorming activities to quantitative function-component analysis. A combination of two such methods—the chi-matrix and morphological matrix techniques—is the basis for this work. Building on existing functionality of the design repository, desired product functions can be specified in a search of stored design knowledge, returning a morphological matrix of artifacts solving the specified functions. Such a search is termed a morphological search. The repository morphological search feature is evaluated against concepts generated in a previous original design project. Results of the morphological search return are then compared to ten of the original concept variants generated during the design project. This comparison shows that 89% of the specified subfunctions return results and that, on average, 77% of the components used in the hand-generated concepts can be derived by using the morphological search feature.

Systematic Design Methods and the Creative Performance of New Product Teams: Do They Contradict or Complement Each Other?

Can organizations exert control and provide structure for NPD activities while at the same time encouraging and managing creative performance? Any new product development (NPD) project requires some level of creative effort. In new product development, creative performance is of preeminent importance. Most NPD projects are executed with the NPD team as the organizational nucleus. As a result, managing creativity in NPD thus implies managing the creativity of NPD teams. Besides having to manage creative performance, companies are generally also concerned with improving the efficiency and effectiveness of the NPD process. Modern NPD projects therefore have the need for an approach that can be planned, optimized, and verified. As a consequence, systematic design methods have become widely used in NPD. In this article conceptual model is developed of the effect of modern design methodology on the creative performance of NPD teams. First, it is argued that the effect of systematic design methodology on NPD team creativity is mediated by the communication patterns of the NPD team. It is then proposed that four principles underlie modern design methodology: hierarchical decomposition, systematic variation, satisficing, and discursiveness. These principles affect NPD communication by, respectively, influencing the establishment of subgroups, the frequency of communication, the level of agreement or disagreement in the team, and the level of centralization of communication. Next, arguments are presented of how each of these four communicational characteristics shapes the creative performance of NPD teams. This second part of the conceptual model is tested empirically. This is done by studying the communication patterns in 44 NPD teams, employing social network analysis tools. These patterns of communication are then related to team‐level creative performance through a set of regression analyses. The main conclusion of the article is that the design principles work together and need to be considered as an integrated whole: the creative performance of NPD teams can only effectively be managed by using and aligning all four of them.

A two-loop excitation control system for synchronous generators

An excitation controller for a single generator based on modern multi-loop design methodology is presented in this paper. The proposed controller consists of two-loops: a stabilizing (damping injection) loop and a voltage regulating loop. The task of the stabilizing loop is to add damping in the face of voltage oscillations. The voltage regulating loop is basically a PI compensator whose objective is to obtain terminal voltage regulation about the prescribed reference. The main contribution of this paper is to give some insights into the systematic derivation of multi-loop controllers of power generators. Certain connections between the two-loop excitation controller and standard PSS–AVR schemes are discussed. In this way, some insight into the stability of the standard PSS scheme is obtained from the analysis of the proposed controller. The proposed controller is evaluated via numerical simulations on a full finite-element model.

The system architecture of the new JET Shape Controller

Abstract This paper describes the installation of the new JET Shape Controller System [M. Garribba, R. Litunovsky, P. Noll, S. Puppin, The new control scheme for the JET plasma position and current control system, in: Proceedings of the 15th SOFE Conference, Massachusetts, 1993, pp. 33–36; F. Sartori, A. Cenedese, Plasma position and current control management at JET, in: Proceedings of the 42nd IEEE Conference on Decision and Control, Maui, 2003] especially focusing on the addition of the Extreme Shape Controller [G. Ambrosino, et al., A new shape controller for extremely shaped plasmas in JET, Fusion Eng. Des. 66–68 (2003) 797–802]. The activity was performed by the JET Operator in co-operation with the ENEA-CREATE design team, and involved both changes in the hardware and system software of JET and tuning of the proposed Extreme Shape Controller (XSC) design to satisfy the practical requirements of tokamak operation. The application of 10 years experience of controller implementation and commissioning combined with a modern and efficient modelling and design methodology has allowed an unprecedented fast and easy commissioning of the new system.

Domestic Wastewater Treatment in Developing Countries

Affordable and effective domestic wastewater treatment is a critical issue in public health and disease prevention around the world, particularly so in developing countries which often lack the financial and technical resources necessary for proper treatment facilities. This practical guide provides state-of-the-art coverage of methods for domestic wastewater treatment and provides a foundation to the practical design of wastewater treatment and re-use systems. The emphasis is on low-cost, low-energy, low-maintenance, high-performance 'natural' systems that contribute to environmental sustainability by producing effluents that can be safely and profitably used in agriculture for crop irrigation and/or in aquaculture, for fish and aquatic vegetable pond fertilization. Modern design methodologies, with worked design examples, are described for waste stabilization ponds, wastewater storage and treatment reservoirs; constructed wetlands, upflow anaerobic sludge blanket reactors, biofilters, aerated lagoons and oxidation ditches. This book is essential reading for engineers, academics and upper-level and graduate students in engineering, wastewater management and public health, and others interested in sustainable and cost-effective technologies for reducing wastewater-related diseases and environmental damage.

Mechatronic systems: Automotive applications and modern design methodologies

Mechatronic systems are used in different fields of application, e.g. industrial goods, consumer products and automotive equipment. Current and future mechatronic as well as micro-electromechanical systems are shown on the basis of technological trends and market requirements, e.g. reduced fuel consumption and emission for automotive technology. Special attention will be devoted to the rapidly growing importance of electronics and software. Effective as well as efficient design of mechatronic systems are fundamental prerequisites for competitiveness in a harsh industrial environment. Modern methodologies for interdisciplinary, model-based design of mechatronic systems are presented; the benefits of these new methods are described.

TOOLS AND TECHNOLOGIES FOR DESIGNING CONTROL SYSTEMS USING PROGRAMMABLE LOGIC DEVICES

The paper presents modern programmable logic devices and design methodologies with appropriate tools reference. It briefly shows enhancements introduced in the architecture of FPGA and its influence on circuit capabilities. The paper presents also the design process from idea to functional implementation. It discusses algorithmic and functional approaches to design. Abstraction level and transaction mechanisms are shown as a method of hiding details without compromising design functionality. Finally tools for different design approaches and design environment requirements are presented.

Effect of earthquake duration on structural reliability

Modern design methodologies rely on accurate estimates of structural reliability indices for code calibration and design. In general, most methodologies do not explicitly account for earthquake duration when calculating reliability indices. This paper presents a summary of a study whose goal was to provide a basic method to better estimate the effect of earthquake duration on structural reliability using (1) an ultimate strength and a (2) low-cycle structural damage-based limit state function. The damage model developed by Park and Ang was coupled with the theory of order statistics all within a Monte Carlo simulation framework in order to estimate the probability of failure for hypothetical groups of structures. Structures were idealized using elasto-plastic oscillators in order to simplify the analysis and make it general enough to compare with future or existing studies. A response database was used to provide randomness beyond the number of time domain simulations initially performed. Existing suites of ground motion time histories were scaled using linear response spectrum scaling for soil conditions using a well-known attenuation relationship. This study is unique in that it allows variation in the peaks of the highly non-linear structural response without actually performing time domain analyses, which are commonly employed in earthquake engineering. A simple measure was introduced and termed the duration effect factor (DEF β ) and is defined as the slope of a best-fit line for multiple reliability indices plotted against duration. The DEF β could help provide a means for comparison between earthquake duration studies, which has otherwise been difficult.

Investigation of Relationship Between Roughness and Pavement Surface Distress Based on WesTrack Project

Modern pavement rehabilitation and design methodologies require an adequate evaluation of the functional capacity of pavements. A key component of this functional capacity is the roughness of the pavement. The current standard for characterization of a pavement’s roughness is the international roughness index (IRI). Pavement roughness measurements were conducted at regular intervals during the application of approximately 5 million equivalent single-axle loads at the WesTrack Project, a full-scale flexible pavement accelerated loading facility located near Reno, Nevada. The results are presented of an investigation into the relationship between pavement roughness and pavement surface distress using WesTrack data. With a sample population of 317 observations, a relationship was found among the roughness (IRI) and the initial IRI, percentage of fatigue cracking, and average rut depth. A test of the relationship with data collected as a part of the Long-Term Pavement Performance Program indicates favorable results.

Unifying via conformal mapping coarse-mesh neutron diffusion calculations in Cartesian and hexagonal geometries

Modern design methodology for nuclear reactor core designs performs routinely three-dimensional core modeling. The modeling is done with a class of highly accurate nodal method of solving the neutron diffusion equation, which is orders of magnitude faster than the finite difference method. However, these modern nodal methods are powerful only for Cartesian geometry problem applications. For hexagonal geometry problems, there is a fundamental difficulty associated with singularities caused by the geometry. Using the invariance property of the diffusion operator under conformal transformations, the singularities can be removed via conformally mapping a hexagonal node to a rectangular node, making it very easy to extend a nodal code from Cartesian geometry applications to hexagonal geometry applications. Thus applications to the two different geometries can be unified in a single nodal code. The method has been implemented in the Westinghouse neutron diffusion code, ANC-H, and demonstrated to work very well.

Neural networks approach to AIAA aircraft control design challenge

This paper focuses on designing a discrete-time lateral-directional control law for a high-performance aircraft using neural networks. The control law structure is composed of feedback and filter components formulated in the form of a three-layer feedforward neural network whose parameters are adjusted by a gradient descent algorithm to provide stabilization about the aircraft center of mass and asymptotic tracking of pilot command input. The number of parameters was chosen in an ad hoc manner. Only rate gyro and lateral accelerometer outputs are available for feedback, whereas rudder pedal and lateral stick commands are input signals to the filter. Linear simulation results at an operating point within the aircraft's envelope in the presence of atmospheric turbulence and actuator and sensor noises shed light on the ability of neural networks to serve as a practical tool for flight control law designers. UMEROUS classical and modern control law design methodologies have been proposed for designing continuous- or discrete-time longitudinal and lateral-directional control laws for aircraft.1'2 These time- and frequency-domain design techniques usually apply to a linear, time-invariant state-space dynamic model of the aircraft from either a single-input, single-output (SISO) or a multi-input, multi-output (MIMO) point of view. However, the aircraft's equations of motion are highly nonlinear in six degrees of freedom (6-DOF) throughout its operating envelope. Thus, those who design control laws for aircraft face some difficulties in extending these techniques to real-flight vehicles. Traditionally, gain scheduling has been employed to compensate for nonlinearity. In this approach, the resulting nonlinear control law for the full-flight envelope is interpolated between various linear controllers scheduled as a function of speed, altitude, and wing loading. However, the desire to enlarge the flight envelope of modern aircraft and to provide enhanced maneuver capabilities may make gain scheduling infeasible due to rapid changes in dynamics. A more sophisticated flight control system that could work well over a wide range of operating conditions is clearly needed. Adaptive control is intended for plant models that must operate in the presence of uncertainty. It utilizes the available a priori knowledge and adapts to the unknown part of the plant such as timevarying parameters. An adaptive flight control system is capable of adjusting on-line the controller's parameters in response to changing flight characteristics.3 However, instability in the adaptive control system in the presence of unmodeled dynamics, bounded input, and

Integrated circuit teaching through top-down design

This paper describes the organization, development, and results of an integrated circuit design course where the bottom-up teaching approach adopted in textbooks has been managed in conjunction with the top-down strategy of modern design methodologies. The deliverables and milestones established for the teaching, learning, and design activities have been successfully met up to the level of obtaining simulation results demonstrating the functional and/or electrical performance of a number of application specific integrated circuits for communication systems which not only exhibit some innovative solutions but also demonstrate potential practical applicability in industry.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>