Publication in the Online First Directory

Recent technological progress has enabled us to meet authors' requirements for shorter publication times. Thus we are pleased to announce that Springer-Verlag is introducing the Online First (OF) publication concept for Acta Informatica. This new facility has been installed by Springer's Internet service (http://www.springerlink.com). From now on papers will be published in electronic form as OF papers shortly after proofs have been corrected by the author and returned to Springer. This means a significant reduction in the publication time. At this stage, OF papers will have no citation line (volume, pages, year) or page numbers but will be marked by an international identification code which can used for citation purposes (see below). A line indicating the exact OF-publication date will be printed beneath the title.For publication in the subsequent print version, the citation line and page numbers will be added, but the content of the article will remain unchanged. Authors will be informed at the proofreading stage that after electronic publication they cannot change the content of a paper, nor can they withdraw it from publication.Each article will be announced by Springer's Alert service. Access to the full papers is restricted to subscribers of the printed version.An OF paper is a genuine publication and not a new form of preprint. It is copyright-protected and it can be cited exactly like any printed paper. An OF paper is citeable by a "Digital Object Identifier" (or DOI), a unique and persistent international identification code, included in both the print and electronic versions. The DOI can also be used to create hyperlinks to OF papers: although files may be moved to other locations on the Springer server after print publication, the DOI is never changed.September 2003     

Multi-grid reduced-order topology optimization

Structural and Multidisciplinary Optimization - Additive printing allows the “single step” production of virtually any complex mechanical component. However, the manufacturing process...     

Shared autonomous electric vehicle design and operations under uncertainties: a reliability-based design optimization approach

Structural and Multidisciplinary Optimization - Shared autonomous electric vehicles (SAEVs) are a promising car-sharing service expected to be implemented in the near future. However, existing...     

Reliability-based topology optimization under shape uncertainty modeled in Eulerian description

Structural and Multidisciplinary Optimization - This paper presents a reliability-based topology optimization method under geometrical uncertainties. First, we briefly introduce the concept of...     

Optimal design of controlled structures

A formulation that finds the optimal design of a controlled structure is proposed. To achieve this goal, a composite objective composed of structural and control objectives is introduced to be optimized, and the effect of the control weighting is examined. A feedback control law is defined before the structural optimization and then the composite objective will only become a function of structural design variables. As a result, optimal structural design and control forces in steady state are obtained.Part of this paper was presented at WCSMO1 (First World Congress of Structural and Multidisciplinary Optimization), held in Goslar, Germany, May 28–June 2, 1995     

Adaptive weighted sum method for multiobjective optimization: a new method for Pareto front generation

This paper presents an adaptive weighted sum (AWS) method for multiobjective optimization problems. The method extends the previously developed biobjective AWS method to problems with more than two objective functions. In the first phase, the usual weighted sum method is performed to approximate the Pareto surface quickly, and a mesh of Pareto front patches is identified. Each Pareto front patch is then refined by imposing additional equality constraints that connect the pseudonadir point and the expected Pareto optimal solutions on a piecewise planar hypersurface in the -dimensional objective space. It is demonstrated that the method produces a well-distributed Pareto front mesh for effective visualization, and that it finds solutions in nonconvex regions. Two numerical examples and a simple structural optimization problem are solved as case studies. Presented as paper AIAA-2004-4322 at the 10th AIAA-ISSMO Multidisciplinary Analysis and Optimization Conference, Albany, New York, August 30–September 1, 2004     

Shape optimization of a dynamically loaded machine foundation coupled to a semi-infinite inelastic medium

A numerical model of the shape optimization of a rectangular machine foundation embedded in soil when subjected to external dynamic forces and moments is presented. A sequential programming method with move limits is used to obtain the minimum weight (mass) of the block. Numerical examples are given to illustrate the application of the model which takes 3-D dynamic soil-foundation interaction into account.Presented at The First World Congress of Structural and Multidisciplinary Optimization (held in Goslar, Germany, May 28–June, 2, 1995)     

A generalized method of moving asymptotes (GMMA) including equality constraints

A convex programming optimizer called GMMA (Generalized Method of Moving Asymptotes) is presented in this paper. This method aims at solving engineering design problems including nonlinear equality and inequality constraints. The basic feature of this optimizer is that the efficient dual solution strategy together with the flexible GMMA approximation scheme are used. Especially, nonlinear equality constraints can be exactly satisfied by the intermediate solution of each explicit subproblem because their linearization is updated in an internal loop of the subproblem. This method will be illustrated by a hydrodynamic design application.Presented at the First World Congress of Structural and Multidisciplinary Optimization (WCSMO-1), held in Goslar, Germany, May 28-June 2, 1995     

Integrated optimal structural and vibration control design

An integrated design procedure which is composed of structural design, control design, and actuator locations design is proposed in this paper. First, a composite objective function, formed by a structural and a control objective, is optimized in steady state through the homogenization design method. Then an independent modal space control algorithm (IMSC) is performed on this optimal structure to reduce the dynamic response. Finally, to minimize the control force while still obtaining the same modal response for the controlled modes, the optimal choice for actuator locations is discussed.Part of this paper was presented in the First World Congress of Structural and Multidisciplinary Optimization (held in Goslar, Germany, May 28–June 2, 1995).     

The Verified Incremental Design of a Distributed Spanning Tree Algorithm: Extended Abstract

The paper announces an incremental mechanically–verified design of the algorithm of Gallager, Humblet, and Spira for the distributed determination of the minimum-weight spanning tree in a graph of processes. The processes communicate by means of asynchronous messages with their neighbours in the graph. Messages over one link may pass each other. The proof of the algorithm is based on ghost variables, invariants, and a decreasing variant function. The verification is mechanized by means of the theorem prover Nqthm of Boyer and Moore. This extended abstract is an introduction to the full paper that can be obtained by ftp (http://link.springer.de/link/service/journals/00165/). Received May 1997 / Accepted in revised form January 1995     

Optimal design of a welded I-section frame using four conceptually different optimization algorithms

The purpose of this study is to investigate the suitability of four conceptually different optimization algorithms for specifically the optimal design of welded I-section frames. The cost function to be minimized is the volume of the frame. Constraints on lateral-torsional buckling as well as local buckling of the beam and column webs and flanges are taken into consideration. The algorithms evaluated include a genetic algorithm, a novel leap-frog gradient method without line searches, as well as an orthogonal search method requiring no gradients and the differential evolution technique. Received September 26, 2001 RID="*" ID="*"Part of this paper was presented at the World Congress on Structural and Multidisciplinary Optimization, June 4–8 2001, Dalian, China     

Multi-information source constrained Bayesian optimization

Structural and Multidisciplinary Optimization - Design decisions for complex systems often can be made or informed by a variety of information sources. When optimizing such a system, the evaluation...     

Network Formation in the Political Blogosphere: An Application of Agent Based Simulation and e-Research Tools

The political blogosphere has become the focus of attention of researchers from disciplines such as political science and network science. In a recent paper, Adamic and Glance (LinkKDD ’05: Proceedings of the 3rd international workshop on link discovery, 2005, pp. 443–452) report differences between the linking behavior of politically conservative versus politically liberal web bloggers. We construct a simple agent-based network formation model which shows that one such difference, demonstrating what we term ‘political homophily’, can be generated by connecting the blogosphere to the underlying population distribution of political preferences. The model is implemented as a web service in the e-Research tool VOSON (Virtual Observatory for the Study of Online Networks), and both model and tool serve to define a natural environment for research into link formation behavior with large numbers of heterogeneous network participants.     

System reliability based vehicle design for crashworthiness and effects of various uncertainty reduction measures

Reliability-based design optimization of automobile structures for crashworthiness has been studied by many researchers by using either single component probabilistic constraints or single failure mode based probabilistic constraints, while system reliability considerations are mostly disregarded. In this paper, we perform system reliability based design optimization (SRBDO) of an automobile for crashworthiness and analyze the effect of reliability allocation in different failure modes. In addition, effects of various uncertainty reduction measures (e.g., reducing variability in material properties, reducing error of finite element analysis) are investigated and tradeoff plots of uncertainty reduction, system reliability and structural weight are generated. These types of tradeoff plots can be used by a company manager to decide whether to allocate the company resources for employing uncertainty reduction measures or allocating the resources for the excess weight to protect against the unreduced uncertainties. Furthermore, relative importance of automobile structural members in different crash scenarios is quantified. Submitted for publication in the Structural and Multidisciplinary Optimization (SMO).     

Incomplete series expansion for function approximation

We present an incomplete series expansion (ISE) as a basis for function approximation. The ISE is expressed in terms of an approximate Hessian matrix, which may contain second, third, and even higher order “main” or diagonal terms, but which excludes “interaction” or off-diagonal terms. From the ISE, a family of approximation functions may be derived. The approximation functions may be based on an arbitrary number of previously sampled points, and any of the function and gradient values at suitable previously sampled points may be enforced when deriving the approximation functions. When function values only are enforced, the storage requirements are minimal. However, irrespective of the conditions enforced, the approximate Hessian matrix is a sparse diagonal matrix. In addition, the resultant approximations are separable. Hence, the proposed approximation functions are very well-suited for use in gradient-based sequential approximate optimization requiring computationally expensive simulations; a typical example is structural design problems with many design variables and constraints. We derived a wide selection of approximations from the family of ISE approximating functions; these include approximations based on the substitution of reciprocal and exponential intervening variables. A comparison with popular approximating functions previously proposed illustrates the accuracy and flexibility of the new family of approximation functions. In fact, a number of popular approximating functions previously proposed for structural optimization applications derive from our ISE. Based on the similarly named paper presented at the Sixth World Congress on Structural and Multidisciplinary Optimization, Rio de Janeiro, Brazil, May 2005     

Sequential optimization and reliability assessment for multidisciplinary design optimization under aleatory and epistemic uncertainties

In engineering design, to achieve high reliability and safety in complex and coupled systems (e.g., Multidisciplinary Systems), Reliability Based Multidisciplinary Design Optimization (RBMDO) has been received increasing attention. If there are sufficient data of uncertainties to construct the probability distribution of each input variable, the RBMDO can efficiently deal with the problem. However there are both Aleatory Uncertainty (AU) and Epistemic Uncertainty (EU) in most Multidisciplinary Systems (MS). In this situation, the results of the RBMDO will be unreliable or risky because there are insufficient data to precisely construct the probability distribution about EU due to time, money, etc. This paper proposes formulations of Mixed Variables (random and fuzzy variables) Multidisciplinary Design Optimization (MVMDO) and a method of MVMDO within the framework of Sequential Optimization and Reliability Assessment (MVMDO-SORA). The MVMDO overcomes difficulties caused by insufficient information for uncertainty. The proposed method enables designers to solve MDO problems in the presence of both AU and EU. Besides, the proposed method can efficiently reduce the computational demand. Examples are used to demonstrate the proposed formulations and the efficiency of MVMDO-SORA.     

International Conference on “Modeling,Simulation, Optimization for Design of Multi-disciplinary Engineering Systems”, Goa,September 2003

The conference is jointly sponsored by the Aeronautical Society of India (AeSI) and International Society of Structural and Multidisciplinary Optimization (ISSMO). The meeting seeks to bring together people in the field of multidisciplinary analysis and design, to discuss the latest advances and developments in the field, especially those that relate to aerospace vehicles and systems design. With an increase in the use of formal design methodology in problems of practical importance, significant new challenges pertaining to representation of the analysis and design problems, solution techniques, computational efficiency, and man-machine interactions have been identified. At the same time, impressive advances in computational algorithms and hardware have contributed to successful applications in problems of nontrivial complexity. The conference invites contributions from researchers in disciplines related to modeling, simulation and optimization in multidisciplinary design. Further information can be obtained from the web address: http://www.casde.iitb.ac.in/mso-dmes/ Received August 8, 2002     

Size optimization of a cantilever beam under deformation-dependent loads with application to wheat stalks

In this paper, we consider the optimization of the cross-section profile of a cantilever beam under deformation-dependent loads. Such loads are encountered in plants and trees, cereal crop plants such as wheat and corn in particular. The wind loads acting on the grain-bearing spike of a wheat stalk vary with the orientation of the spike as the stalk bends; this bending and the ensuing change in orientation depend on the deformation of the plant under the same load. The uprooting of the wheat stalks under wind loads is an unresolved problem in genetically modified dwarf wheat stalks. Although it was thought that the dwarf varieties would acquire increased resistance to uprooting, it was found that the dwarf wheat plants selectively decreased the Young’s modulus in order to be compliant. The motivation of this study is to investigate why wheat plants prefer compliant stems. We analyze this by seeking an optimal shape of the wheat plant’s stem, which is modeled as a cantilever beam, by taking the large deflection of the stem into account with the help of co-rotational finite element beam modeling. The criteria considered here include minimum moment at the fixed ground support, adequate stiffness and strength, and the volume of material. The result reported here is an example of flexibility, rather than stiffness, leading to increased strength. This work was presented at the 7th World Congress on Structural and Multidisciplinary Optimization (WCSMO-7), May 21–25, 2007, Seoul, Korea.