Design optimization

The SARA satellite was conceived as a microgravity recoverable and reusable research platform by both Brazilian Institute of Aeronautics and Space (IAE) and Space Agency (AEB). Figure 1a shows an artistic design of the platform and Fig. 1b, the planned launch vehicle of the spacecraft. The satellite was designed to carry a 55 kg payload mass, with total launch mass not exceeding 350 kg. Missions were projected to take place in circular orbits at 300 km altitude, with two-degree inclination. After completion of the microgravity experiments, up to ten days, the reentry procedure began by providing the right positioning of the satellite followed by the deboost impulse. Final deceleration took place by a high performance parachute system (Koldaev and Moraes, 1997). The spacecraft was scheduled to pass through a series of uali cation tests in ballistic ights reaching 350 km apogee and falling at about 300 km from the launch site. The system should be accelerated by a Brazilian VS-40 sounding rocket (Fig. 1b). To date, solid and liquid rocket propulsion systems were the only technological means considered for the deboost

A complete analysis of low-noise 0.1 m gate AlInAs/GaInAs HEMT's has been performed by using a semiclassical Monte Carlo simulation. The validity of the model has been checked through the comparison of the simulated results with static, dynamic and noise experimental measurements of real HEMTs. In order to reproduce the experimental results, we have included in the model some important real effects such as degeneracy, surface charges, T-shape of the gate, presence of dielectrics and contact resistances. Moreover, the extrinsic parameters of the devices have been added to the usual intrinsic small-signal equivalent circuit, thus allowing the calculation of the real noise of the HEMTs (characterized using the extrinsic minimum noise . In this way, we make possible not only the comparison with the experimental noise results, but also the analysis of the influence of the parasitic elements, the device width or the number of gate fingers on the noise of the HEMTs. The reliability of the simulator allows us to realize "computer experiments" which will make faster and cheaper the optimization process of the device design. for his work on the modeling and the characterization of MES-FETs and HEMTs. In 1977, he joined the Centre Hyperfrequences et Semiconducteurs, University of Lille, France. He is now Professor of electronics at the University of Lille. His main research interests are concerned with the modeling, the realization and the characterization of low noise devices for application in the centimeter and millimeter wave ranges.

The m i n i " system tempentture design of MCMs containing a number of chips of equal power for design in natwal convection is pursued through the optimal thermal placement of chips. For dealing with the thermal optimization problems, a simple but effective thermal design methodology that integrates a modified forcedirected (FD) algorithm and a finite element (FE) modeling technique is proposed. In the FD algorithm, novel force functions that include attractive and repulsive forces are proposed, which are built up, as a function of location and power of chips, based on the modeled actual temperature information through FE analysis, a response surface method WM) and an intmpolation scheme. The sum of these forces within the system, approximating the total system chip junction temperature, is considered as the objective of the optimization problem, and nonoverlapping conditions between chips are imposed as geometry constraints. The optimum locations of these chips are sought through an iteratwe search of the entire design space based on two proposed searching strategies. To demonstrate the effectiveness of the current design optimization methodology, severid design case studies involving direct chip attached (DCA) typed MCMs containing a number of chips of equal power are performed. The obtained results am: extensively compared against the published data.

This paper aims to develop and validate an ANSYS finite element model to predict both the cured shape and snap-through of unsymmetric bistable laminates actuated by piezoelectric macro fibre composites attached to the laminate. To fully describe piezoelectric actuation the three dimensional compliance [s ij ], piezoelectric [d ij ] and relative permittivity [ε ij ] matrices were formulated for the macro fibre actuator. The deflection of an actuated isotropic aluminium beam was then modelled and compared to experimental measurements to validate the data. The model was then extended to bistable laminates actuated using macro fibre composites. Model results were compared to experimental measurements of laminate profile (shape) and snap-through voltage. The modelling approach is an important intermediate step toward enabling design of shape-changing structures based on bistable laminates.

This paper presents a design optimization problem reformulation method based on Singular Value Decomposition (SVD), dimensionality reduction, and unsupervised clustering. The method calculates linear approximations of the associative patterns of symbol co-occurrences in a design problem representation to infer induced interaction/coupling strengths between variables and constraints. Unsupervised clustering of these approximations is used to identify useful reformulations. These two components

A Decision Support System (DSS) to support sustainable development planning processes in the agricultural sector has been developed in the context of the research project entitled WATER MAP (Development and utilization of vulnerability maps for the monitoring and management of groundwater resources in the Archimed area), which is an Interreg -Archimed project. The model is based on vulnerability maps and facilitates and optimizes the decision-making process relating to the problems of land use, water management and environmental protection. The spatial integration of the vulnerability maps in the DSS enables regional authorities to design optimal spatial development policies. The DSS is based on a Multicriteria Mathematical Programming model and can achieve the optimum agricultural production plan in the area combining different criteria to a utility function under a set of constraints concerning different categories of land, labour, available capital, etc. The model is further used to simulate different scenarios and policies due to changes on different social, economic and environmental parameters. In this way we get alternative production plans and agricultural land uses as well as the economic, social and environmental impact of different policies.

This work presents a formal probabilistic approach for solving optimization problems in design automation. Prediction accuracy is very low especially at high levels of design flow. This can be attributed mainly to unawareness of low level layout information and variability in fabrication process. Hence a traditional deterministic design automation approach where each cost function is represented as a fixed value becomes obsolete. A new approach is gaining attention in which the cost functions are represented as probability distributions and the optimization criteria is probabilistic too. This design optimization philosophy is demonstrated through the classic buffer insertion problem . Formally, we capture wirelengths as probability distributions (as compared to the traditional approach which considers wirelength as fixed values) and present several strategies for optimizing the probabilistic criteria. During the course of this work many problems are proved to be NP-Complete. Comparisons are made with the Van-Ginneken "optimal under fixed wire-length" algorithm. Results show that the Van-Ginneken approach generated delay distributions at the root of the fanout wiring tree which had large probability (0.91 in the worst case and 0.55 on average) of violating the delay constraint. Our algorithms could achieve 100% probability of satisfying the delay constraint with similar buffer penalty. Although this work considers wirelength prediction inaccuracies, our probabilistic strategy could be extended trivially to consider fabrication variability in wire parasitics.

In an effort t o improve and automate the fluid dynamic design of rotary blood pumps, a coupled computational fluid dynamics (CFD) shape optimization methodology has been developed and implemented. This program couples a finite element flow simulation with a gradient-based optimization routine to modify automatically the shape of an initial candidate blood path, according to a variety of desired fluid dynamic criteria, including shear stress, vorticity/circulation, and viscous dissipation. Preliminary results have led to both intuitive and nonintuitive transformations of the initial blood flow

Process synthesis is one of the important aspects in the design of adsorption processes, especially in the case of pressure swing adsorption (PSA) processes. A process simulator which can help in taking decisions on the number of beds, operating configurations and operating parameters (pressure ratio, cycle step times, flow velocity, feed/purge ratio, etc.) can minimize the necessity of pilot plant studies, resolve commissioning problems and help in optimal operation. This work makes an attempt at simulation based on-line synthesis, design and optimization of PSA processes. A simulation/tuning/optimization software has been developed for PSA processes for multicomponent separation. Adaptive simulation based process synthesis and optimization strategies have been demonstrated using a rigorous simulation (called Process) as an emulation of a flexible PSA plant instead of an actual plant and a less rigorous model as its simulation. The findings based on this study appear to be an effective approach to optimal synthesis, design and optimization of any PSA processes.

Decrease of the drain silicide-blocking-to-gate spacing in gate-silicided-ESD-NMOSFETs improves the TLP and HBM failure levels up to 30%, while no effect is observed when decreasing the source silicide-blocking-to-gate spacing. Failure analysis and simulation results show that current crowding in the drain silicide region accounts for the difference in failure current for the devices.

Adaptive polar work-function predistortion (WFP) reduces the spectral regrowth of radio frequency power amplifiers such as those used in the telecommunications industry. This paper describes adaptive polar WFP equations and a system implementation. The system description includes an adaptive digital signal processing (DSP) algorithm based on measurement of outof-band performance. It includes a discussion of the strengths and weaknesses of the DSP algorithm used and presents some current results with wide-band modulation signals.

This paper proposes the real-coded clonal selection algorithm (RCSA) for use in electromagnetic design optimization. Some features of the algorithm, such as the number of clones, mutation range, and the fraction of the population selected each generation are discussed. The TEAM Workshop problem 22 is investigated, in order to illustrate the performance of the algorithm in a real electromagnetic problem. The results obtained, a set of optimal solutions representing a broader range of options for the designer, are compared with those achieved by a genetic algorithm, showing the efficiency of the RCSA in practical optimization problems.

Current Computer Aided Design (CAD) software tools focus on rapid production of computer models, which usually takes place after the product design is completed. The product design process, which has more significant influence on product life-cycle costs, is not fully supported. This work documents the development of an automatic design and optimization system for industrial silencers. The developed system greatly reduces the production costs and shortens the silencer design time from one day to a few minutes. Moreover, the system proves the feasibility of developing an open-architecture CAD system supported by Design of Experiment (DOE) based optimization methods to integrate product life-cycle considerations into the design. It is expected that the developed system can help the development of similar systems for other products. Through the development of this system, some further research issues are identified.

Efficiency maximization of a three phase squirrel-cage induction motor with constraints imposed upon the performance characteristics of the motor is carried out. Initially a computer program, based upon the numerical and analytical design procedures, has been developed for the design of a three phase squirrel-cage induction motor and its calculated performance has been validated against the performance of the squirrel-cage motor of standard commercial design. The output of this program is the input of the optimization program. A non-linear optimization routine for the motor design is used and this optimized design is compared with those obtained using other optimization procedures and a more complicated optimization procedure. The pattern search method of Hooke-Jeeves is used successfully, by direct imposition of constraints, for optimum design of a 5 h.p. motor. The results of the optimization consisting of variations of the performance conditions and relative variations of these characteristics, are then compared with the results of the optimization based upon the Han-Powell procedure, simple and modified Hooke-Jeeves methods. This comparison indicates that, in spite of different optimization variables and routines used, the relative variations of the performance characteristics are similar.

Currently, many optimizations of sequential circuits, even as simple as retiming, are avoided due to the lack of verification tools that support them. Doing general sequential equivalence to compare the circuits is impractical for circuits of a reasonable size. On the other hand, combinational optimization is part of the design process, because tools and methods are available to ensure correctness and verify combinational circuits. We present a practical method to verify sequential circuits equivalence using combinational equivalence on a transformed circuit of the same size, for a class of circuits. The constraint imposed is that for each loop in the circuit, there must be a point in both circuits that are in correspondence. The circuits can have a different number of clock phases, and they can be transformed by other scheduling algorithms than retiming and multi-phase retiming.

The inverse dynamic model of a multibody system is used for many applications in engineering. A very interesting property of these models is that they can be written in a linear form with respect to the inertial parameters of the solids, provided that some conditions hold. This property is very helpful in fields like dynamic parameter identification, design optimization, model reduction and others.

In this paper, we present design of a transdermal drug delivery system for treatment of cardiovascular or hemodynamic disorders such as hypertension. The system comprises of integrated control electronics and microelectromechanical system devices such as micropump, micro blood pressure sensor and microneedle array. The objective is to overcome the limitations of oral therapy such as variable absorption profile and the need for frequent dosing, by fabricating a safe, reliable and cost effective transdermal drug delivery system to dispense various pharmacological agents through the skin for treatment of hemodynamic dysfunction such as hypertension. Moreover, design optimization of a piezoelectrically actuated valveless micropump is presented for the drug delivery system. Because of the complexity in analysis of piezoelectric micropump, which involves structural and fluid field couplings in a complicated geometrical arrangement, finite element (FE) numerical simulation rather than an analytical system has been used. The behavior of the piezoelectric actuator with biocompatible polydimethylsiloxane membrane is first studied by conducting piezoelectric analysis. Then the performance of the valveless micropump is analyzed by building a three dimensional electric-solid-fluid model of the micropump. The effect of geometrical dimensions on micropump characteristics and efficiency of nozzle/diffuser elements of a valveless micropump is investigated in the transient analysis using multiple code coupling method. The deformation results of the membrane using multifield code coupling analysis are in good agreement with analytical as well as results of single code coupling analysis of a piezoelectric micropump. The analysis predicts that to enhance the performance of the micropump, diffuser geometrical dimensions such as diffuser length, diffuser neck width and diffuser angle need to be optimized. Micropump flow rate is not strongly affected at low excitation frequencies from 10 to 200 Hz. The excitation voltage is the more dominant factor that affects the flow rate of the micropump as compared with the excitation frequency. However, at extremely high excitation frequencies beyond 8,000 Hz, the flow rate drops as the membrane exhibits multiple bending peaks which is not desirable for fluid flow. Following the extensive numerical analysis, actual fabrication and performance characterization of the micropump is presented. The performance of the micropump is characterized in terms of piezoelectric actuator deflection and micropump flow rate at different operational parameters. The set of multifield simulations and experimental measurement of deflection and flow rate at varying voltage and excitation frequency is a significant advance in the study of the electric-solid-fluid coupled field effects as it allows transient, three dimensional piezoelectric and fluid analysis of the micropump thereby facilitating a more realistic multifield analysis. The results of the present study will also help to conduct relevant strength duration tests of integrated drug delivery device with micropump and microneedle array in future.

A methodology is presented for optimizing the suspension damping and stiffness parameters of nonlinear quarter-car models subjected to random road excitation. The investigation starts with car models involving passive damping with constant or dual-rate characteristics. Then, we also examine car models where the damping coefficient of the suspension is selected so that the resulting system approximates the performance of an active suspension system with sky-hook damping. For the models with semi-active or passive dual-rate dampers, the value of the equivalent suspension damping coefficient is a function of the relative velocity of the sprung mass with respect to the wheel subsystem. As a consequence, the resulting equations of motion are strongly nonlinear. For these models, appropriate methodologies are first employed for obtaining the second moment characteristics of motions resulting from roads with a random profile. This information is next utilized in the definition of a vehicle...

Abslruct-The paper describes a Genetic Algorithm for the Floorplan Area Optimization problem. The algorithm is based on suitable techniques for solution encoding and evaluation function definition, effective cross-over and mutation operators, and heuristic operalors which further improve the method's effectiveness. An adaptive approach automatically provides the optimal values for the activation probabillities of the operators. Experimental results show that the prloposed method is competitive with the most effective ones as far as the CPU time requirements and the result accuracy is considered, but it also presents some advantages. It requires a limited amount of memory, it is not sensible to special structures which are critical for other methods, and has a comlplexity which grows linearly with the number of implementations. Finally, we demonstrate that the method is able to handle floorplans much larger (in terms of number of basic rectangles) than any benchmark previously considered in the literature.

This paper deals with an electromagnetic device optimization for a new de-stacking process of aluminum sheets. In a first step, we present the principle for generation of the adequate field strength by an electromagnetic separator device. In a second step, we use a simple and efficient method to calculate the three-dimensional (3D) electromagnetic field and we propose a pattern of current density distribution in an aluminum sheet. Finally, this modeling process leads to the calculation of the de-stacking strength and in so doing to the optimum design for an electromagnetic separator device.

Decomposition-based strategies, such as analytical target cascading (ATC), are often employed in design optimization of complex systems. Achieving convergence and computational efficiency in the coordination strategy that solves the partitioned problem is a key challenge. A new convergent strategy is proposed for ATC, which coordinates the interactions among subproblems using sequential lineralizations. Linearity of subproblems is maintained using L ∞ norms to measure deviations between targets and responses. A subproblem suspension strategy is used to temporarily suspend inclusion of subproblems that do not need significant redesign, based on trust region and target value step size. The proposed strategy is intended for use in optimization problems where sequential linearizations are typically effective, such as problems with extensive monotonicities, large number of constraints relative to variables, and propagation of probabilities with normal distributions. Experiments with test problems show that, relative to standard ATC coordination, the number of subproblem evaluations is reduced considerably while maintaining accuracy.

Optimization often focuses only on the variation of parameters while neglecting the consideration of alternative systems. However, the rearrangement of the components of a design offers important scope for improvement. To deal with such variations concerning the system structure of models for multidisciplinary design optimization (MDO), this paper proposes a framework for generating models dynamically using a design grammar with an underlying component-oriented analysis. Decomposition and modification rules support the derivation of alternative optimization model and the formalization of system changes. By linking qualitative characteristics with quantitative analyses, the components serve to assign architectural qualities to economic and environmental resources such as costs and energy consumption and thus to include non-numerical, qualitative characteristics within numerical optimization. The approach is developed with the help of a frame-based hall design and demonstrates system modifications of the optimization model by a specific rule set. The rule set focuses on the structural design but considers the effects for the other essential disciplines involved in the design case. The setup and the prototypical implementation of an optimization model for this design illustrate a way of including grammar-based system variations in MDO.

This paper presents a new pipelined architecture to deal with range reduction for floating point representation. It is based on Horner's scheme and a look-up table. The overall design has been optimized for a module equal to 2π, which is the most widely used due to trigonometric functions requirements. To ensure an accuracy of one unit in the last place (ULP), a complete error propagation study has been carried out.

Most rapid prototyping (RP) additive techniques are expensive and suffer from a lack of efficiency when massive products are to be manufactured. The authors propose to reduce the density of rapid prototyped parts, finding alternative building styles. Topologically optimized parts have been created with internal geometry, using a narrow-waisted structure that avoids the need for building supports. In order to characterise and study the behaviour of the obtained low density parts, an experimental plan has been designed and executed. The approach has been tested using a fused deposition modelling (FDM) machine, but it is of a general nature and can be applied to other layered manufacturing (LM) technologies that use supports, dealing with slow building of massive parts.

20 The Dynamically Dimensioned Search (DDS) continuous global optimization algorithm by 21 Tolson and Shoemaker [2007] is modified to solve discrete, single-objective, constrained Water 22 Distribution System (WDS) design problems. The new global optimization algorithm for WDS 23 optimization is called Hybrid Discrete Dynamically Dimensioned Search (HD-DDS) and 24 combines two local search heuristics with a discrete DDS search strategy adapted from the 25 continuous DDS algorithm. The main advantage of the HD-DDS algorithm compared with other 26

Using a detailed system model as a comparison, this study shows that isolating the condenser component and optimizing it independently by minimizing the entropy generation in the condenser component alone, also known as thermoeconomic isolation, is a practical way to design the condenser for optimum airconditioning system efficiency. This task is accomplished by comparing the optimum design determined by maximizing the entire system's COP, an undisputed method, with the optimum design determined by minimizing the entropy generation in the isolated condenser component, with consistent constraints used for the two methods. The choice of constraints used in the isolated model is critical and discussed in detail. The resulting optimum designs from the isolated model produced a COP within 0.62% to 1.7% of the designs found by optimizing the COP using an entire system model. Additionally, a 65% reduction in computation time was achieved.

We study the problem of query optimization in federated relational database systems. The nature of federated databases explicitly decouples many aspects of the optimization process, often making it imperative for the optimizer to consult underlying data sources while doing costbased optimization. This not only increases the cost of optimization, but also changes the trade-offs involved in the optimization process significantly. The dominant cost in the decoupled optimization process is the "cost of costing" that traditionally has been considered insignificant. The optimizer can only afford a few rounds of messages to the underlying data sources and hence the optimization techniques in this environment must be geared toward gathering all the required cost information with minimal communication.

Using the technology of spectral selectivity to integrate different solar power generators in a hybrid system is a feasible way to improve the optical-electric efficiency. This paper presents an 82-layer broadband optical interference thin-film filter matching with crystalline silicon photovoltaic cells, which using TiO 2 and SiO 2 as fabrication materials and can be used in hybrid solar power systems like photovoltaic-thermoelectric generator (PV-TEG) systems. The design, optimization and fabrication process of the filter is described, high reflectance from 400 nm to 1100 nm as well as high transmittance from 1100 nm to 2500 nm over the broadband of solar spectrum are obtained. The classical electron beam evaporation plant is used to fabricate the filter. Four different incidence angles' optical performances of the sample filter are measured which agree well with the numerical simulation results. The electrical characteristics of a typical Silicon photovoltaic cell using the fabricated sample filter are measured. An average efficiency increase of 3.24% for the solar cell with respect to the solar energy it receives can be obtained due to the filter. A calculation model for a hybrid PV-TEG system using this thin-film filter is proposed and the benefits of the filter for hybrid solar power systems are demonstrated.

In the Army mechanical fatigue subject to external and inertia transient loads in the service life of mechanical systems often leads to a structural failure due to accumulated damage. Structural durability analysis that predicts the fatigue life of mechanical components subject to dynamic stresses and strains is a compute intensive multidisciplinary simulation process, since it requires the integration of several

This paper attempts to perform thermal enhancement of planar multiple-chip modules (MCMs) containing a number of chips of equal and/or unequal power through optimal chip placement design. To achieve the goal, an effective design approach is presented for the thermal design optimization problems in the context of models of placement of chips in MCMs. The approach combines the use of the currently proposed response surface (RS) based methodology, which is an optimization algorithm and a finite element modeling technique. The proposed RS-based methodology is used for creating a macro mathematical expression of the design objective of the thermal optimization problem, i.e., the total chip junction temperature of the system, associated with the design parameters, including the chip location and power. The validity of the mathematical expressions constructed is verified through two approaches. Furthermore, to make the constructed mathematical expression more compact while maintaining the associated solution accuracy, the backward variable elimination technique is employed. The effectiveness of the proposed design optimization methodology is demonstrated through several design case studies involving planar plastic ball grid array type MCMs. It is found that the proposed RS-based methodology could accurately define the macro mathematical model of the total system chip junction temperature in terms of the chip location and power. In addition, results show that the current optimal chip placement design can provide a minimal system temperature.

A thorough analysis of a polymer electrolyte membrane (PEM) fuel cell system is presented. A generalized performance model of a single PEM fuel cell is developed and applied in a semi-empirical form for a Ballard Mark V 35-cell, 5 kW PEM fuel cell. A thermodynamic and economic analysis of the components and of the whole system is performed. The purpose of this study is to explore the intrinsic relations among various fuel cell system performance and cost indicators in order to provide insights for new cost effective and high performance designs. Optimization techniques have been applied in order to determine the optimal design and operation mode of the system. An application of the system onboard merchant ships has been considered as an example.

This paper focuses on the demonstration of an integrated aerostructural method for the design of aerospace vehicles. Both aerodynamics and structures are represented using high-fidelity models such as the Euler equations for the aerodynamics and a detailed finite element model for the primary structure. The aerodynamic outer-mold line and a structure of fixed topology are parameterized using a large number of design variables. The aerostructural sensitivities of aerodynamic and structural cost functions with respect to both outer-mold line shape and structural variables are computed using an accurate and efficient coupled-adjoint procedure. Kreisselmeier-Steinhauser functions are used to reduce the number of structural constraints in the problem. Results of the aerodynamic shape and structural optimization of a natural laminar-flow supersonic business jet are presented together with an assessment of the accuracy of the sensitivity information obtained using the coupled-adjoint procedure.

Process-induced variations are an important consideration in the design of integrated circuits. Until recently, it was sufficient to model die-to-die shifts in device performance, leading to the well known worst-case modeling and design methodology . However, current and near-future integrated circuits are large enough that device and interconnect parameter variations within the chip are as important as those same variations from chip to chip. This presents a new set of challenges for process modeling and characterization and for the associated design tools and methodologies.

Sommario Il lavoro ha come oggetto lo studio numerico di un freno a fluido magnetoreologico (MR) per uso automobilistico tramite il codice agli elementi fin iti ANSYS. In seguito ad un dimensionamento analitico preliminare del freno la realizzazione di un modello FEM magnetico permette un'accurata valutazione della distribuzione del campo magnetico nel fluido MR e la valutazione del momento frenante

Transforming analog graphic data, such as maps, into digital format by manual digitizing is slow and expensive, but is nevertheless widely performed. Studies of digitizing methods to find opportunities for optimization are therefore warranted. The work reported here investigates the possibility of applying the Keystroke-Level Model to the modeling and optimization of manual map digitizing tasks. We tested the suitability of the model for manual digitizing at a national mapping agency and determined unit tasks with their performance times. The paper describes the design of an experiment to measure performance times under production conditions. Two new keystroke level operators are defined for manual digitizing. The use and suitability of the model are demonstrated by analyzing the differences between predicted and measured performance times for unit tasks. The results confirm the applicability and the economic importance of keystroke-level analyses of real world tasks.

This paper presents a study of a roll compaction process as a dry granulation method for typical food materials such as maize powder. This process is widely applied in industry as it can continuously produce large quantities of granular product at comparatively low cost. The objectives of this work were to predict the roll compaction performance from a simple measurement involving uniaxial die compaction using the classical Johanson model. This involved determination of the optimum operating conditions for the production of granules as evaluated by apparent density.

We introduce in this paper a new problem of post-mask engineering change order (ECO) timing optimization using spare-cell rewiring and present a two-phase framework for this problem. Spare-cell rewiring is a popular technique for incremental timing optimization and/or functional change after the placement stage. The spare-cell rewiring problem is very challenging because of its dynamic wiring cost nature for selecting a spare cell, while the existing related problems consider only static wiring cost: once a standard cell is placed, its physical location is fixed and so is its wiring cost. For the sparecell rewiring problem, each rewiring could make some spare cells become ordinary standard cells and some standard cells become new spare cells simultaneously. As a result, the wiring cost becomes dynamic and further complicates the optimization process. For the addressed problem, we present a two-phase framework of 1) buffer insertion and gate sizing followed by 2) technology remapping. For Phase 1, we present a dynamic programming algorithm considering the dynamic cost, called dynamic cost programming, for the ECO timing optimization with spare cells. Without loss of solution optimality, we further present an effective pruning method by selecting spare cells only inside an essential bounding polygon to reduce the solution space. For those ECO timing paths that cannot be fixed during Phase 1, we apply technology remapping on the spare cells to restructure the circuit to fix the timing violations. The whole framework is integrated into a commercial design flow. Experimental results based on five industry benchmarks show that our method is very effective and efficient in fixing the timing violations of ECO paths.

This paper emphasizes the necessity of formally bringing qualitative and quantitative criteria of ergonomic design together, and provides a novel complementary design framework with this aim. Within this framework, different design criteria are viewed as optimization objectives, and design solutions are iteratively improved through the cooperative efforts of computer and user. The framework is rooted in multiobjective optimization, genetic algorithms, and interactive user evaluation. Three different algorithms based on the framework are developed, and tested with an ergonomic chair design problem. The parallel and multiobjective approaches show promising results in fitness convergence, design diversity, and user satisfaction metrics.

In this chapter we consider reduced basis (RB) approximation and a posteriori error estimation for linear functional outputs of affinely parametrized linear parabolic partial differential equations. The essential ingredients are Galerkin projection onto a low-dimensional space associated with a smooth parametrically induced manifolddimension reduction; efficient and effective POD-Greedy RB sampling methods for identification of optimal and numerically stable approximations spaces -rapid convergence; rigorous and sharp a posteriori error bounds for the linear-functional outputs of interest -certainty; and Offline-Online computational decomposition strategies -minimum marginal cost. The RB approach is effective in the real-time context in which the expensive Offline stage is deemed unimportant -for example parameter estimation and control; the RB approach is also effective in the many-query context in which the expensive Offline stage is asymptotically negligible -for example design

In this paper we discuss the often overlooked timeliness property of fair exchange protocols. We gather different available definitions of this property, and propose a new and stronger interpretation for timeliness in the context of security protocols. We discuss common timeliness-related pitfalls in fair exchange protocol design, and show a particular timeliness attack effective in several optimistic protocols proposed in the literature. Finally, we provide guidelines that may help to avoid common mistakes in protocol design, and propose our own protocol that ensures both fairness and timeliness.