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We are all makers, constantly using tangible and intangible tools to craft our reality. There is an intentionality around the life that Allan Jones has crafted for himself. The photographer, [...]

One is a nonprofit social services organization in the Midwest. The other is a state human services agency in the Southwest. Though separated by more than a thousand miles, they [...]

Health and human services programs play a vital role in people's lives by providing health care and other needs-based social safety nets. Too often, the human experience of recipients engaging [...]

Immediately upon securing the Normandy beachheads in World War II, American forces were faced with a task for which they were wholly unprepared. The breakout from Normandy required Allied forces [...]

Design patterns provide reusable solutions for recurring design problems. They constitute an important tool for improving software quality. However, correct usage of design patterns depends to a large extent on the designer. Design patterns often include models that describe the suggested solutions, while other aspects of the patterns are neglected or described informally only in text. Furthermore, design pattern solutions are usually described in an object-oriented fashion that is too close to the implementation, masking the essence of and motivation behind a particular design pattern. We suggest an approach to modeling the different aspects of design patterns and semi-automatically utilizing these models to improve software design. Evaluating our approach on commonly used design patterns and a case study of an automatic application for composing, taking, checking, and grading analysis and design exams, we found that the suggested approach successfully locates the main design problems modeled by the selected design patterns. Keywords: Conceptual Modeling, Design Improvement, Design Patterns, Domain Engineering, Model Retrieval, Object-Process Methodology (OPM), Pattern Recognition, Unified Modeling Language (UML), INTRODUCTION Patterns are types of themes that specify recurring processes, events, or elements. Commonly used in different engineering fields, patterns can be classified into analysis patterns, design patterns, organization patterns, [...]

A technique is described for parameterizing geometries in a manner suitable for numerical simulations used in design optimization. The new methodology, referred to as 'control grids,' is flexible, easy to use, extendable, and applicable to multidisciplinary design optimization. Although significantly different than free-form deformation, the present method provides many similar capabilities. Comparisons between the current technique and free-form deformation are provided to highlight the advantages and disadvantages of each method. The new parameterization technology is described and demonstrated in both two and three dimensions for single and multidisciplinary applications. DOI: 10.2514/1.41101

In reliability-based design optimization problems with correlated input variables, a joint cumulative distribution function needs to be used to transform the correlated input variables into independent standard Gaussian variables for the inverse reliability analysis. To obtain a true joint cumulative distribution function, a very large number of data (if not infinite) needs to be used, which is impractical in industry applications. In this paper, a copula is proposed to model the joint cumulative distribution function using marginal cumulative distribution functions and correlation parameters obtained from samples. Using the joint cumulative distribution function modeled by the copula, the transformation and the first-order reliability method can be carried out. However, the first-order reliability method may yield different reliability analysis results for different transformation ordering of input variables. Thus, the most probable-point-based dimension reduction method, which is more accurate than the first-order reliability method and more efficient than the second-order reliability method, is proposed for the inverse reliability analysis to reduce the effect of transformation ordering.

The design process is difficult to accelerate due to its iterative nature, which increases project cost and delays completion time of a design project. Many previous studies tried to find the optimal structure and sequence of a design process minimizing iteration. In a multiproject environment, however, waiting time caused by resource shortage is a more critical reason for a lengthy project than iteration time. In this paper, we propose a novel sequencing method that reduces waiting time in a multiproject environment by dynamically changing the sequence of design tasks, according to availability of resources. It is called a dynamic sequencing method, as opposed to the traditional static sequencing method by which every design project follows a predefined optimal sequence. In order to evaluate the effect of this method, we developed a design-process model for simulating iteration and waiting in a multiproject environment. The simulation results show that dynamic sequencing is significantly better than traditional static sequencing with respect to average duration of projects. It is noted that more significant improvements can be obtained for the bottlenecked and unbalanced processes, both of which conditions would otherwise have negative effects on process performance. [DOI: 10.1115/1.3066599] Keywords: design process, multiproject environment, dynamic sequencing, DSM, stochastic processing network

In this paper, we present a methodology that helps select the distribution parameters in degrading multiresponse systems to improve dependability at the lowest lifetime cost. The dependability measures include both quality (soft failures) and reliability (hard failures). Associated costs of scrap, rework, and warrantee work are included. The key to the approach is the fast and efficient creation of the system cumulative distribution function through a series of time-variant limit-state functions. Probabilities are evaluated by Monte Carlo simulation although the first-order reliability method is a viable alternative. The cost objective function that is common in reliability-based design optimization is expanded to include a lifetime loss of performance cost, herein based on present worth theory (also called present value theory). An optimum design in terms of distribution parameters of the design variables is found via a methodology that involves minimizing cost under performance policy constraints over the lifetime as the system degrades. A case study of an over-run clutch provides the insights and potential of the proposed methodology. [DOI: 10.1115/1.3013295] Keywords: dependability, quality, reliability, design, limit-state function, loss of performance cost, present worth

A new multiresponse and multistage metamodeling approach is developed for design optimization. Distinct from the existing objective-oriented sequential sampling methods, where the design objective and constraints have to be combined into a single response of interest, our method offers the flexibility of building metamodels for multiple responses (objective/constraints) simultaneously. Uncertainty quantification is introduced for each metamodel to represent the confidence interval due to the lack of sufficient sample points. Based on the extreme values of the optimal solution identified within the confidence interval, the level set representation, together with a series of Boolean operations, is used to synthesize the region(s) of interest with arbitrary topologies. Introducing the level set representation into the metamodeling process facilitates manipulations of regions formed by different responses, the representation of disconnected regions of interest, and the visualization for design exploration. Through mathematical benchmark examples and an engineering design problem, we demonstrate that the proposed method possesses superior efficiency in design exploration and allows multiple sample points at each sampling stage. As the metamodeling process moves on, the region of interest is progressively reduced, and the optimal design is asymptotically approached. Our results are compared with those from one-stage metamodeling using the optimal Latin hypercube experiments and from the sequential metamodeling using the efficient global optimization algorithm to demonstrate the efficiency and effectiveness of our method. DOI: 10.2514/1.38187

The stationarity requirement for the process generating the data is a common assumption in classifiers' design. When such hypothesis does not hold, e.g., in applications affected by aging effects, drifts, deviations, and faults, classifiers must react just in time, i.e., exactly when needed, to track the process evolution. The first step in designing effective just-in-time classifiers requires detection of the temporal instant associated with the process change, and the second one needs an update of the knowledge base used by the classification system to track the process evolution. This paper addresses the change detection aspect leaving the design of just-in-time adaptive classification systems to a companion paper. Two completely automatic tests for detecting nonstationarity phenomena are suggested, which neither require a pr/or/information nor assumptions about the process generating the data. In particular, an effective computational intelligence-inspired test is provided to deal with multidimensional situations, a scenario where traditional change detection methods are generally not applicable or scarcely effective. Index Terms--Intelligent systems, learning systems, neural networks, pattern classification.

Lamination parameters have proven to be exceedingly useful for the efficient design optimization of composite structures due to their continuous nature and flexibility in the final choice of stacking sequence with a reduced number of design variables. So far, failure criteria could only be incorporated into the lamination parameter design space for a predefined combination of fiber angles. This drastically limits the design space available to the designer. This paper investigates incorporating the Tsai--Wu failure criterion into the lamination parameter design space in the most general setting. A conservative failure envelope is derived that guarantees a failure-free region of the lamination parameter space regardless of the fiber orientations in the laminate stacking sequence. The proposed approach allows strength criteria to be included both as a constraint as well as an objective function during the optimization process. The derived strength envelope is then used to compare strength- and stiffness-based designs. The results clearly indicate that the degree of correlation between stiffness- and strength-driven designs depends on the properties of the material under consideration.

As an enabling feed/interconnect element for various millimeter wave components, dual polarization quasi-transverse electromagnetic (TEM) waveguides at W-band (75-110 GHz) are investigated with two-dimensional electromagnetic crystal (EMXT) surfaces as the four boundary walls instead of the regular metallic walls. A 2.54 mm x 2.54 mm quasi-TEM square waveguide prototype with a length of 2 mm is fabricated and demonstrated. Both eigenmode and full-wave EM simulations of the prototype verify the quasi-TEM propagation at the designed frequency of 95 GHz with a bandwidth of more than 10% and the low insertion loss for the entire W-band. The prototype waveguide is measured in a WR-10 fixture and the results agree with simulations well. To better understand the loss mechanisms, various design and packaging parameters are studied. Undesirable resonant surface modes have been identified as a critical cause of loss at specific frequencies. This type of waveguides may also be useful for spatial power combining, low loss interconnects, and packaging for millimeter wave systems. Index Terms--Electromagnetic crystal, millimeter wave (mmW), quasi-transverse electromagnetic (TEM) waveguide, surface mode.

A novel approach is developed to design linear passive retro-directive antenna arrays by properly making use of 90[degrees] hybrids. For a 90[degrees] hybrid, when its direct port and coupled port are terminated with the same reflection coefficient, the phase difference of the reflected signals at the other two ports are reversed to that of the incident signals. This then becomes to be a phase difference reversal circuit (or a retro-directive circuit) and leads to the design of linear retro-directive antenna arrays using 90[degrees] hybrids. The formulas and a folding method on designing linear retro-directive array circuits with arbitrary element numbers are presented with the measurement results of three-element, four-element, and six-element retro-directive antenna arrays. Index Terms--90[degrees] hybrid, phase difference reversal, retro-directive antennas.

A novel miniaturized cavity-backed composite slot loop antenna (CBCSLA) with low profile and omnidirectional radiation similar to a short dipole is presented. The antenna displays vertical polarization while having less than [lambda]/100 dimension in height. The geometry of the antenna is inspired from a small magnetic loop which is realized using a slot configuration on metallic ground. Since a small slot loop antenna cannot be impedance matched, a composite geometry is devised that acts like as a small slot loop and can easily be impedance matched using this configuration. The diameter of the CBCSLA can be made as small as [lambda]/10 or smaller. The feeding mechanism is designed in a manner to create a circumferentially-constant current distribution around the composite loop while effectively matching to a 50 [OMEGA] coaxial feed from the antenna center. Additional methods are discussed to further enhance the bandwidth and achieve a dual-band response. The antennas are designed, fabricated, and measured. It is shown that despite their small lateral dimension and extremely small height, the miniaturized cavity-backed slot loop features extremely well input impedance match, uniform radiation pattern, low cross-polarization levels and expected gain. Index Terms--Cavity-backed antennas (CBAs), dipole antennas, dual-band antennas, omnidirectional antennas, slot antennas.

A two-layer reflectarray is proposed as a central station antenna for a local multipoint distribution system (LMDS) in the 24.5-26.5 GHz band. The antenna produces three independent beams in an alternate linear polarization that are shaped both in azimuth (sectored) and in elevation (squared cosecant). The design process is divided into several stages. First, the positions of the three feeds are established as well as the antenna geometry to produce the three beams in the required directions. Second, the phase distribution on the reflectarray surface, which produces the required beam shaping, is synthesized. Third, the sizes of the printed stacked patches are adjusted so that the phase-shift introduced by them matches the synthesized phase distribution. Finally, the radiation patterns are computed for the central and lateral beams, showing a shaping close to the requirements. A breadboard has been manufactured and measured in an anechoic chamber, showing a good behavior, which validates the designing methodology. Index Terms--Local multipoint distribution system (LMDS), multibeam antenna, multifeed reflectarray, reflectarray, shaped beam antenna.

Two-arm sinuous antennas are introduced in this paper. The proposed configurations and realized phase progressions result in a unique multiband behavior with alternating polarization handedness between adjacent bands. Two sinuous embodiments are presented: a planar, cavity backed, flush mountable design and a unidirectional, conically projected structure. Both designs exhibit multiband and multipolarized performance with low axial ratio and good pattern symmetry. Conical sinuous has superior impedance matching, wider bandwidth for all circularly polarized bands and does not require absorber backing for unidirectional radiation. A computer aided analysis is performed using method of moments and finite element codes and results are favorably compared with measurements. Index Terms--Conical, multiband, multipolarized, sinuous antenna, spiral.

This paper introduces a new modeless modular compensating strategy to extract and mitigate power-quality (PQ) disturbances. The main advantage of this strategy is that it does not require any model or state-space formulation to extract the disturbances, such as the other commonly used state-space techniques. In addition, it is very simple for practical implementation compared to the time-domain and frequency-domain methods. The proposed strategy depends on recursive implementation of the Wiener filtering theory. The suggested strategy is validated by digital simulation results on the most common stationary and transient PQ problems. Index Terms--Modular compensating strategy, power-quality (PQ) problems and recursive Wiener filter.

In the course of designing and analyzing electromagnetic devices, open boundary field problems often need to be solved. The mapping of the infinite exterior of a finite circular region onto the interior of that closed circular region has emerged and established itself as one of the best methods. However, as a result of the work done in the past in solving homogenous exterior regions, this paper shows that this mapping method has been mistakenly taken to apply only when the exterior consists of air or, at best, some other homogeneous medium. This paper validates the method for problems with uniformly inhomogeneous exterior regions and makes possible the solution of a new class of problems by this powerful method. Index Terms--Computational theory, computer-aided analysis, design automation, electromagnetic fields, finite elements.

This paper presents an optimal approach to designing electrical machines to reduce mechanical deformation caused by magnetic nodal forces in magnetomechanical systems, while maintaining the force calculated using Coulomb's virtual work (CVW) method. It derives a design sensitivity equation by employing the adjoint variable method (AVM) to avoid undertaking numerous sensitivity evaluations for the coupled analysis. IT verifies the sensitivity analysis by using the finite-difference method (FDM). The paper examines a simple core used in a magnetic levitation system for optimal design, demonstrating the strength of the new topology optimization approach. Index Terms--Compliance, design sensitivity equation, magnetic nodal force, magnetomechanics, topology optimization.

A straightforward means to reduce the mass of a truss beam is to replace some of its rigid members with prestressed tendons. Such a solution, however, involves unique design considerations, most of which have been previously unaddressed in the literature. The present paper seeks to fill this gap by reviewing the general mechanics of and some specific design considerations for a basic class of such structures: regular triangular truss beams with tendon diagonals. The issues considered and illustrated in the context of three architectural options are the pretension necessary for tautness, member vibration, parasitic force effects, truss face accuracy, longeron compression eccentricities, and stiffness. This review offers not only design formulas for one redundant and two determinate variants of the considered class of trusses, but also a blueprint for the systematic analysis and design of other trusses with prestressed members. Two specific details of the involved derivations bear further significance: 1) some shear compliance formulas regularly used for truss beam Timoshenko continuum modeling are shown to be flawed and are corrected and 2) it is illustrated that structural asymmetry may be beneficial: the stiffness of an asymmetrically laced beam is shown to exceed that of its symmetric alternative.

The increasing operating frequencies in modern designs call for broadband macromodeling techniques. The problem of computing high-accuracy simulation models for high-speed interconnects is of great importance in the modeling arena. Nowadays, many full-wave numerical techniques are available that provide high accuracy, often at a significant cost in terms of memory storage and computing time. Furthermore, designers are usually only interested in a few electrical quantities such as port voltages and currents. So, model order reduction techniques are commonly used to achieve accurate results in a reasonable time. This paper presents a new technique, based on the partial element equivalent circuit method, which allows to generate reduced-order models by adaptively selecting the complexity (order) of the macromodel and suitable frequency samples. Thus, the proposed algorithm allows to limit the computing time while preserving the accuracy. Validation examples are given. Index Terms--Adaptive frequency sampling (AFS), electromagnetic transient analysis, fitting techniques, frequency response, partial element equivalent circuit (PEEC) method.

Our objectives were to develop two 9 x 9 and 10 x 10 array high resolution position sensitive block detectors using low cost Photomultiplier-Quadrant-Sharing (PQS) technology. These two blocks can decode 4.3 mm or 3.9 mm BGO crystals with [PHI] 39 mm size regular round PMT. By using ESR film as reflector between crystals, we achieved 96% packing fractions for these two blocks. Compared with conventional block design using 19 mm or 26 mm PMT, [PHI] 39 mm size PMT can reduce the number of PMT in a camera by 55%-75%. Use of BGO crystal can reduce crystal cost by more than 70% compared to LSO or GSO crystals that are used in some of the newest PET cameras. The BGO crystal sizes-4.3 mm or 3.9 mm-in these two PQS blocks were similar to or smaller than BGO, LSO, or GSO crystals (4-6.3 mm) in commercial human PET cameras. The spatial resolution of the PQS blocks was expected to be similar or better. List mode data of these two blocks were acquired with Na-22 source. Crystal-decoding map of blocks and individual crystal spectra were derived. All 9 x 9 and 10 x 10 crystals were clearly decoded on the block decoding map. These two PQS detectors decoded 81 or 100 BGO crystals per PMT. The average peak to valley ratio of decoding map was 3.4 and 1.8 respectively. The light collection efficiency for all crystals in the blocks were 71%-100% and 66%-100% respectively. The average energy resolutions of all crystals were 16.8% and 17.2% respectively. Our data suggest that even at lower cost the new PQS PET camera may outperform recent conventional PET cameras. Index Terms--Photomultiplier -quadrant-sharing (PQS), position sensitive detector, positron emission tomography (PET), scintillation detector.

We present design studies of the DAQ and trigger system (DAT) for the PANDA detector proposed for the new FAIR facility at GSI. The broad physics program of PANDA requires a novel DAT system able to cope with high interaction rates (up to 2*[10.sup.7] Hz) and to trigger on various event topologies simultaneously. We used SystemC as a modeling platform to investigate candidate architecture for the PANDA DAT system. We simulated the behavior of the complete system with simplified models of all the components. The model covers detector buffers connected via Ethernet to farms of computing nodes constituting two filtering levels and an event building level. We present results from modeling illustrating the impact of the key architectural choices and parameters on the overall performance. Index Terms--Data acquisition systems, modeling real-time systems, real-time architectures, trigger.

Current testbenches for nuclear imaging devices aim to simulate only a single stage of the system at a time. This approach is useful in early design stages where accuracy is not necessary. However, it would be desirable that different tools could be combined to achieve more detailed simulations. In this work, a high precision testbench is presented. It has been developed to test nuclear imaging systems. Its accuracy lies in the possibility of linking different simulation tools using the right one for each part of the system. High energy events are simulated using Geant4 (High Energy Simulator). Analog and digital electronics are verified using SpectreVerilog or UltrasimVerilog (Cadence Design Syst. Inc., San Jose, CA, USA) and ModelSim (Mentor Graphics Corp, Wilsonville, OR, USA). This testbench structure can be used to test any physical topology, scintillation crystals, Photomultiplier Tubes (PMTs), Avalanche Photodiodes (APDs), with any kind of ASIC, discrete analog and digital electronics, thus reducing the prototyping and design time. New system developments can be easily verified using behavioral and circuital description models for analog and digital electronics. Finally, a dual-head continuous LSO scintillation crystal Positron Emission Tomography (PET) system has been used as an example for evaluation of the testbench. Index Terms--Biomedical nuclear imaging, design methodology, positron emission tomography (PET), simulation, system analysis and design.

Infrasound is a low frequency acoustic phenomenon that typically ranges from 0.01 to 20 Hz. The data collected from infrasound microphones are presented online by the infrasound monitoring system operating in Northern Europe, i.e., the Swedish-Finnish Infrasound Network (SFIN). Processing the continuous flow of data to extract optimal feature information is important for real-time signal classification. Performing wavelet decomposition on the real-time signals is an alternative. The purpose of this paper is to present the design and FPGA implementation of discrete wavelet transforms (DWT) for real-time infrasound data processing; our approach uses only two FIR filters, a high-pass and a low-pass filter. A compact implementation was realized with pipelining techniques and multiple use of generalized building blocks. The design was described in VHDL and the FPGA implementation and simulation were performed on the QUARTUS II platform. Index Terms--Discrete wavelet transform (DWT), FPGA, filtering, infrasound.

Product development (PD) processes are complex and unstructured compared to business or manufacturing processes, as they have iterative, evolutionary, uncertain, and cooperative features. In order to effectively manage and control a complex PD process, appropriate and logical descriptions are needed. This requires a modeling framework that can capture its characteristics. However, previous modeling methodologies are limited in terms of representing the characteristics. To cope with this limitation, we propose a modeling framework that can address the typical features of the PD process. To this end, we classify PD characteristics systematically and define modeling constructs for the PD process with modeling patterns and parameters. The proposed modeling framework will provide engineers and managers with a basis for planning, organizing, analyzing, and monitoring complex PD processes effectively. Index Terms--Design iteration, modeling framework, overlap, patterns, product development (PD) process.

We provide a detailed review of existing object-oriented software development methodologies, focusing on their development processes. The review aims at laying bare their core philosophies, processes, and internal activities. This is done by using a process-centered template for summarizing the methodologies, highlighting the activities prescribed in the methodology while describing the modeling languages used (mainly diagrams and tables) as secondary to the activities. The descriptions produced using this template aim not to offer a critique on the methodologies and processes, but instead provide an abstract and structured description in a way that facilitates their elaborate analysis for the purposes of improving understanding, and making it easier to tailor, select, and evaluate the processes. Categories and Subject Descriptors: D.2.1 [Software Engineering]: Requirements/Specifications--Methodologies; D.2.2 [Software Engineering]: Design Tools and Techniques--Object-oriented design methods; D.2.9 [Software Engineering]: Management--Life cycle; K.2 [History of Computing]:--Software; K.6.1 [Management of Computing and Information Systems]: Project and People Management--Systems analysis and design; systems development; K.6.3 [Management of Computing and Information Systems]: Software Management--Software development; Software process General Terms: Design, Management Additional Key Words and Phrases: Object-oriented methodologies, seminal methodologies, agile methods, integrated methodologies, methodology engineering ACM Reference Format: Ramsin, R. and Paige, R. F. 2008. Process-centered review of object oriented software development methodologies. ACM Comput. Surv. 40, 1, Article 3 (February 2008), 89 pages. DOI = 10.1145/1322432.1322435 http://doi.acm.org/10.1145/1322432.1322435

This paper establishes a new profile, viz. recto-trapezoidal (RT) of an absorber plate fin on the basis of ease of fabrication as well as augmentation of heat transfer rate per unit fin volume. An analytical model has been developed for evaluating the thermal performance and optimum dimensions of an absorber plate fin using this typical profile. The present study is equally suitable for an absorber plate fin having a rectangular, trapezoidal or triangular profile also with consideration of their respective geometrical parameters. The optimization of the RT profile has been cast in a generalized form either by maximizing heat transfer rate for a given fin volume or by minimizing fin volume for a given heat transfer duty. From the optimum design analysis, significant results have been noticed when an additional constraint is imposed with the fin volume. Under this design condition, it may also be highlighted that for an optimal circumstance, the heat transfer rate through a RT profile absorber plate fin is greater than a trapezoidal or triangular profile for the same fin volume. However, this observation may be restricted to the limited values of fin volume only. The optimum design analysis for the RT profiled absorber plate fin has also been studied under the different design constants. Finally, for the variation of all the design variables, optimum design curves have been generated for a wide range of thermo-geometric parameters. Keywords: Absorber plate fin; Flat-plate collector; Optimization; Performance indicator; Recto-trapezoidal profile; Trapezoidal profile

In reliability-based design optimization, the constraints consider the probability of the satisfaction/failure of critical events. Lately, reliability-based design optimization has been applied to topology optimization, resulting in the development of reliability-based topology optimization. And though reliability-based topology optimization can be a useful and meaningful method, it requires excessive computational resources. Therefore, this research proposes a parallel-computed reliability-based topology optimization using the response surface method. This paper demonstrates that the proposed method greatly reduces the computation requirement of reliability-based topology optimization. The proposed methodology is then applied to design microelectromechanical systems. Specifically, in microelectromechanical systems, reliability-based topology optimization can be highly effective because of randomness generated during the etching process and scaling effect. The proposed method successfully designs new devices and verifies the designs via experiment.

This paper is about the development of systems whose end users are professional people working in a specific domain (e.g., medicine, geology, mechanical engineering); they are expert in that domain, but not necessarily expert in nor even conversant with computer science. In several work organizations, end users need to tailor their software systems to better adapt them to their requirements and even to create or modify software artifacts. These are end-user development activities and are the focus of this paper. A model of the interaction between users and systems, which also takes into account their reciprocal coevolution during system usage, is discussed. This model is used to define a methodology aimed at designing software environments that allow end users to become designers of their own tools. The methodology is illustrated by discussing two experimental cases. Index Terms--Design methodology, user-centered design, user interface human factors, visual languages.

The study on epistemic uncertainty due to the lack of knowledge has received increasing attention in risk assessment, reliability analysis, decision making, and design optimization. Different theories have been applied to model and quantify epistemic uncertainty. Research on sensitivity analysis for epistemic uncertainty has also been initialized. Sensitivity analysis can identify the contributions of individual input variables with epistemic uncertainty to the model output. It then helps guide the collection of more information to reduce the effect of epistemic uncertainty. In this paper, an effective sensitivity analysis method for epistemic uncertainty is proposed when both epistemic and aleatory uncertainties exist in model inputs. This method employs the unified uncertainty analysis framework to calculate the plausibility and belief measures. The gap between belief and plausibility measures is used as an indicator of the effect of epistemic uncertainty on the model output. The Koimogorov-Smirnov distance between the two measures is used to quantify the main effect and the total effect of each independent variable with epistemic uncertainty. By the Kolmogorov-Smirnov distance, the importance of each variable is ranked. The feasibility and effectiveness of the proposed method is demonstrated with two engineering examples.

This paper presents the design concepts and realization of incorporating micro-operation simulation and FPGA implementation into a teaching tool for computer organization and architecture. This teaching tool helps computer engineering and computer science students to be familiarized practically with computer organization and architecture through the development of their own instruction set, computer programming and interfacing experiments. A two-pass assembler has been designed and implemented to write assembly programs in this teaching tool. In addition to the micro-operation simulation, the complete configuration can be run on Xilinx Spartan-3 FPGA board. Such implementation offers good code density, easy customization, easily developed software, small area, and high performance at low cost. Key Words: Teaching tool, Computer organization and architecture, Processor design, Microprogramming, Assembler design, FPGA implementation., INTRODUCTION Computer organization and architecture is a common course that is offered at universities throughout the world (1). Traditionally, teaching such a course to computer engineering and computer science students [...]

New classes of compliant long dwell mechanism designs are introduced, formulated, and simulated. These classes of compliant dwell mechanisms incorporate the buckling motion of flexible members. Long dwell motion is obtained throughout the buckling motion of a flexible follower. Flexible buckling members are modeled using polynomial functions fitted to nonlinear inextensible exact elastica theory. The displacement analysis of the mechanisms is done quasi-statically using loop closure theory, static equilibrium of flexible parts represented by polynomial load deflections. One example of each new mechanism and its simulation results are presented. [DOI: 10.1115/1.2735337]

This paper presents the design of a mechanism with the following specifications: continuous alternate motion, wide motion phases with constant angular velocity, parallel input and output shafts, and great strokes. Those specifications derive from a possible application in the textile field. The mechanism is composed of two star wheels properly coupled together: there are two counter-rotating input wheels, alternately coupling with slots first, then teeth at each side of the output wheel. As usual for star wheels, pins and slots handle the acceleration and deceleration phases, while the constant velocity phase is performed by coupling sectors of toothed gears. A proper design of pins and slots is performed, so that at the same time when a pin from one input wheel is releasing a slot, a pin from the other input wheel engages a slot on the other side of the output wheel, forcing the latter to an opposite motion. In this way the output wheel has a continuous and smooth alternate motion. By annihilating the arrest phases typical of star wheels, the proposed system eliminates the discontinuities in the acceleration diagram. The paper develops a complete parametrical analysis of the device, underlining the effect of the constraints on the shape of the motion laws with particular emphasis on the acceleration and deceleration phases. In this way the output wheel has a continuous and smooth alternate motion. With respect to an analogous mechanism realizing the same laws of motion, e.g., cams, this device is very compact and economical, also presenting parallel input and output shafts, and significantly reduces sliding and wear. [DOI: 10.1115/1.2735638] Keywords: kinematics, mechanism design, star wheel, alternate motion

Most real-world design problems are complex and multidisciplinary, with almost always more than one objective (cost) function to be extremized simultaneously. The primary goal of this research is to develop a framework to enable multi-objective optimization of multidisciplinary design applications, wherein each discipline is able to retain substantial autonomous control during the process. To achieve this end, we have extended the capability of the concurrent subspace optimization method to handle multi-objective optimization problems in a multidisciplinary design optimization context. Although the conventional concurrent subspace optimization approach is easily able to deal with multi-objective optimization problems by applying the weighted sum approach, the main disadvantage is that the weighted sum cannot capture Pareto points on any nonconvex part of the Pareto frontier. Moreover, an aggregate objective function simply cannot reflect the true spirit of the concurrent subspace optimization method, which was developed to allow groups of specialists to independently have more control over their own design criteria and goals, even while maintaining system level coordination. In this paper, the multi-objective Pareto concurrent subspace optimization method is proposed in which each discipline has substantial control over its own objective function during the design process, while still ensuring responsibility for constraint satisfaction in coupled subspaces. The proposed approach is particularly useful given the realities of geographical distribution, computational platform variation, and dependence upon legacy codes within individual disciplines that so predominates the design of large-scale products such as aircraft and automobiles. As part of the multi-objective Pareto concurrent subspace optimization method developed here, it is demonstrated that the endpoints of the Pareto frontier can be easily identified, together with an ability to generate Pareto points within prescribed limits to ensure a reasonably even distribution across the entire frontier. The approach is validated (using three multidisciplinary design optimization test problems) against Pareto frontiers generated using the weighted sum approach.

Aeroengines are designed using fractured processes. Complexity has driven the design of such machines to be subdivided by specialism, customer, and function. While this approach has worked well in the past, with component efficiencies, current material performance, and the possibilities presented by scaling existing designs for future needs becoming progressively exhausted, it is necessary to reverse this process of disintegration. Our research addresses this aim. The strategy we use has two symbiotic arms. The first is an open data architecture from which existing disparate design codes all derive their input and to which all send their output. The second is a dynamic design process management system known as 'SignPosting.' Both the design codes and parameters are arranged into complementary multiple level hierarchies: fundamental to the successful implementation of our strategy is the robustness of the mechanisms we have developed to ensure consistency in this environment as the design develops over time. One of the key benefits of adopting a hierarchical structure is that it confers not only the ability to use mean-line, throughflow; and fully 3D computational fluid dynamics techniques in the same environment, but also to cross specialism boundaries and to insert mechanical, material, thermal, electrical, and structural codes, enabling exploration of the design space for multi-disciplinary nonlinear responses to design changes and their exploitation. We present results from trials of an early version of the system applied to the redesign of a generic civil aeroengine core compressor. SignPosting has allowed us to examine the hardness of design constraints across disciplines which has shown that it is far more profitable not to strive for even higher aerodynamic performance, but rather to improve the commercial performance by maintaining design and part-speed pressure ratio stability and efficiency while increasing rotor blade creep life by up to 70%. [DOI: 10.1115/1.2472416]

A very general and robust approach to solving continuous-variable optimization problems involving uncertainty in the objective function is through the use of ordinal optimization. At each step in the optimization problem, improvement is based only on a relative ranking of the uncertainty effects on local design alternatives, rather than on precise quantification of the effects. One simply asks, 'Is that alternative better or worse than this one?' not 'How much better or worse is that alternative to this one?' The answer to the latter question requires precise characterization of the uncertainty, with the corresponding sampling/integration expense for precise resolution. However, in this paper, we demonstrate correct decision-making in a continuous-variable probabilistic optimization problem despite extreme vagueness in the statistical characterization of the design options. We present a new adaptive ordinal method for probabilistic optimization in which the tradeoff between computational expense and vagueness in the uncertainty characterization can be conveniently managed in various phases of the optimization problem to make cost-effective stepping decisions in the design space. Spatial correlation of uncertainty in the continuous-variable design space is exploited to dramatically increase method efficiency. Under many circumstances, the method appears to have favorable robustness and cost-scaling properties relative to other probabilistic optimization methods, and it uniquely has mechanisms for quantifying and controlling error likelihood in design-space stepping decisions. The method is asymptotically convergent to the true probabilistic optimum, and so could be useful as a reference standard against which the efficiency and robustness of other methods can be compared, analogous to the role that Monte Carlo simulation plays in uncertainty propagation.

High mast lighting structures are being used to provide illumination for large intersections, particularly for highways located in rural areas. These structures, ranging from approximately 15-40 m (50-130 ft) in height, are exposed to high wind forces that in turn produce a tremendous number of loading cycles each year. A recent high mast lighting structural support failure in the high plains of Colorado near Denver International Airport provided the impetus for this study. These high-mast structures are less than one meter (3.28 ft) in diameter and are quite flexible relative to many civil engineering structures. This flexibility results in large deformations when compared to their diameter, i.e., when combined with the height of these structures. Furthermore, large forces and moments at the base are produced that result in large stresses and stress reversals during multimode excitation. This paper presents the process and results for the development of a reliability-based design procedure for high-mast lighting structural supports based on fatigue life. The resulting procedure is prescriptive in that a series of design charts result from full nonlinear finite element analysis. The loading on the slender body is characterized by Morison's equation, essentially providing the nonlinear loading relationship for the wind on the moving structure. Then, a well-known random vibrations approach was coupled with Miner's rule to estimate the fatigue life of the structural support. Several illustrative design examples are presented and shown to compare very well with full simulations. DOI: 10.1061/(ASCE)0887-3828(2007)21:3(193) CE Database subject headings: Fatigue; Lighting; Structural reliability; Steel; Wind loads.

This paper describes the development and application of design charts for piled embankment designs. It outlines the computational approach adopted, the geotechnical profiles used, and the application of the design procedure using the charts. The soil profile used for the charts is representative of a Malaysian soft clay profile, involving a more or less normally consolidated soil, with a strength and stiffness that varies linearly with depth. Such a profile is typical of the ground conditions in a variety of countries in the Southeast Asian region. The design charts address the issues of pile capacity, settlement due to embankment load, settlement due to a temporary piling construction platform, and lateral response of piles near the edge of the embankment. The charts consider variations in ground conditions, embankment height, pile length, and pile spacing. An illustrative example is given to demonstrate the use of the charts. DOI: 10.1061/(ASCE)1090-0241(2007)133:5(493) CE Database subject headings: Embankments; Foundation design; Lateral displacement; Pile foundations; Settlement; Soil settlement; Clays; Soft soils.

In this paper we examine how soft systems methodology (SSM) can benefit the initial identification and communication of new computer game concepts between those involved in its development. Computer games are a multi-billion pound worldwide part of the entertainment industry. However, they are a relatively new type of software product and as such the manner in which they are designed and developed is still evolving. Computer games can be highly complex software systems that involve the expertise of a wide range of professionals ranging from programmers to animators, artists and musicians. When designing computer games, new game concepts can be difficult to communicate. In addition, the creative process could be benefited if game design ideas were capable of being shared widely and discussed. Keywords soft systems computer game design, INTRODUCTION Although computer games may be viewed as purely a form of entertainment (Schaefer and Warren, 2004), computer games are not necessarily solely for amusement. Combat simulation computer games have [...]

Traditional rigid-body mechanisms consist of a number of components to implement their functions. Therefore they face problems such as backlash, wear, increase in part-count, weight, assembly cost and time, regular maintenance. Reducing these problems will help in increasing mechanism performance and cost reduction. Recently, there are several examples of compliant mechanisms that have been designed and widely used in various fields such as for adaptive structures, biomedical, hand-held tools, components in transportations, MEMS and robotics. However, the largest challenge was relative difficulty in analyzing and designing compliant mechanisms. Two approaches known in the literature for the systematic synthesis of compliant mechanisms are the kinematics-based approach and the structural optimisation based approach. Key words: Compliant mechanisms, rigid-body mechanisms, kinematics and structural optimisation based approach, INTRODUCTION A compliant mechanism can be defined as singlepiece flexible structure, which uses elastic deformation to achieve force and motion transmission. (1),(2). It gains some or all of its motion [...]

Current turbomachinery design systems increasingly rely on multistage CFD as a means to diagnose designs and assess performance potential. However, design weaknesses attributed to improper stage matching are addressed using often ineffective strategies involving a costly iterative loop between blading modification, revision of design intent, and further evaluation of aerodynamic performance. A scheme is proposed herein which greatly simplifies the design point blade row matching process. It is based on a threedimensional viscous inverse method that has been extended to allow blading analysis and design in a multi-blade row environment. For computational expediency, blade row coupling is achieved through an averaging-plane approximation. To limit computational time, the inverse method was parallelized. The proposed method allows improvement of design point blade row matching by direct regulation of the circulation capacity of the blading within a multistage environment. During the design calculation, blade shapes are adjusted to account for inflow and outflow conditions while producing a prescribed pressure loading. Thus, it is computationally ensured that the intended pressure-loading distribution is consistent with the derived blading geometry operating in a multiblade row environment that accounts for certain blade row interactions. The viability of the method is demonstrated in design exercises involving the rotors of a 2.5 stage, highly loaded compressor. Individually redesigned rotors display mismatching when run in the 2.5 stage, evident as a deviation from design intent. However, simultaneous redesign of the rotors in their multistage environment produces the design intent, indicating that aerodynamic matching has been achieved. [DOI: 10.1115/1.2372773] Keywords: inverse aerodynamic shape design, multistage turbomachinery CFD, compressor stage matching

Design of an optimal controller minimizing the integral of squared error (ISE) of the closed-loop system for an interval plant via evolutionary approaches is proposed in this paper. Based on a worst-case design philosophy, the design problem is formulated as a minimax optimization problem from the signal energy point of view, and subsequently solved by two interactive genetic algorithms. To ensure robust stability of the closed-loop system, root locations of the Kharitonov polynomials associated with the characteristic polynomial are used to establish a constraint handling mechanism for incorporation into the fitness function to effectively evaluate chromosomes in the current population. To accelerate the derivation process to obtain the optimal controller, alternative approaches based on the two-phase evolutionary scheme are also proposed, in which the worst-case ISE is suitably estimated via information provided by the Kharitonov plants. Thus, the derived controller not only stabilizes the interval plant, but also minimizes the ISE criterion of the closed-loop system. Constraints on higher order plants and controller order commonly encountered by conventional design methods are therefore removed by using the proposed approach. Index Terms--Genetic algorithms, integral of squared error (ISE), interval plants, minimax optimization, robust controllers, signal energy.

Because deterministic optimum designs obtained without taking uncertainty into account could lead to unreliable designs, a reliability-based approach to design optimization is preferable using a Reliability-Based Design Optimization (RBDO) method. A typical RBDO process iteratively carries out a design optimization in an original random space (X-space) and a reliability analysis in an independent and standard normal random space (U-space). This process requires numerous nonlinear mappings between X- and U-spaces for various probability distributions. Therefore, the nonlinearity of the RBDO problem will depend on the type of distribution of random parameters, since a transformation between X- and U-spaces introduces additional nonlinearity into the reliability-based performance measures evaluated during the RBDO process. The evaluation of probabilistic constraints in RBDO can be carried out in two ways: using either the Reliability Index Approach (RIA), or the Performance Measure Approach (PMA). Different reliability analysis approaches employed in RIA and PMA result in different behaviors of nonlinearity for RIA and PMA in the RBDO process. In this paper, it is shown that RIA becomes much more difficult to solve for non-normally distributed random parameters because of the highly nonlinear transformations that are involved. However, PMA is rather independent of probability distributions because it only has a small involvement with a nonlinear transformation.

We present a method for estimating the parameter sensitivity of a design alternative for use in single objective robust design optimization. The method is non-gradient based: it is applicable even when the objective function of an optimization problem is non-differentiable and/or discontinuous with respect to the parameters. Also, the method does not require a presumed probability distribution for parameters, and is still valid when parameter variations are large. The sensitivity estimate is developed based on the concept that associated with each design alternative there is a region in the parameter variation space whose properties can be used to predict that design's sensitivity. Our method estimates such a region using a worst-case scenario analysis and uses that estimate in a bi-level robust optimization approach. We present a numerical and an engineering example to demonstrate the applications of our method.

This paper focuses on the potential of programming as a link between design and facility management. Not well understood and usually avoided, the promise of programming as a key activity is presented as a dynamic and flexible tool for identifying client-user facility expectations and requirements in the entire project-delivery process. In this context, facility management is proposed as a strategic resource and partner together with all the parties involved. Hinging on the design perspective, an analysis of the current practice and a modified framework are introduced, which suggests relying on facility management data, feedback, and involvement throughout the project delivery process. DOI: 10.1061/(ASCE)0887-3828(2003) 17:1 (4) CE Database keywords: Facilities; Design; Management

Surgical instruments consist of basic mechanical components such as gears, links, pivots, sliders, etc., which are common in mechanical design. This paper describes the application of a method in the analysis and design of complex surgical instruments such as those employed in laparoscopic surgery. This is believed to be the first application of type synthesis theory to a complex medical instrument. Type synthesis is a methodology that can be applied during the conceptual phase of mechanical design. A handle assembly from a patented laparoscopic surgical stapler is used to illustrate the application of the design method developed. Type synthesis is applied on specific subsystems of the mechanism within the handle assembly where alternative design concepts are generated. Chosen concepts are then combined to form a new conceptual design for the handle assembly. The new handle assembly is improved because it has fewer number of parts, is a simpler design and is easier to assemble. Surgical instrument designers may use the methodology presented here to analyze the mechanical subsystems within complex instruments and to create new options that may offer improvements to the original design. [DOI: 10.1115/1.1468635]

A unified unsteady hypersonic/supersonic panel method has been developed and incorporated into ZAERO (a unified unsteady/steady aerodynamics/aeroelasticity methodology/software for aeroelastic applications). The present unified panel method is a viable design/analysis tool for future hypersonic flight vehicles and hypervelocity missiles. The method is established with a rotationality correction function to the general three-dimensional linear potential solution. An equivalent Mach number transformation is introduced to circumvent the superinclined panel limitation. Next, a local pulsating cone analogy is applied to each panel considered, thus yielding the in-phase and out-of-phase forces and moments for an arbitrary body with proper rotationality correction based on steady/unsteady Euler solutions. The obtained results were verified and validated with CFL3D solutions, AP98 results, and measured data. For all cases studied, the unified panel method is found to be computationally efficient (2-3 min per case), acceptably accurate, and very versatile in its applicability, including aerodynamic/stability derivative/aeroelastic/aeroservoelastic applications for complex wing-body or missile-fin configurations in the unified hypersonic/supersonic flight regime.