Computational design techniques for reduced-order compensators

The authors propose two computational techniques for the pole-placement problem using reduced-order compensators. Computationally efficient algorithms are presented for the observer-based compensator and the Brasch-Pearson compensator. The key tool for these algorithms is the concept of two coupled Sylvester equations, the solutions of which completely characterize the desired reduced-order compensators     

Computational procedures for plastic shakedown design of structures

The minimum volume design problem of elastic perfectly plastic finite element structures subjected to a combination of fixed and perfect cyclic loads is studied. The design problem is formulated in such a way that incremental collapse is certainly prevented. The search for the structural design with the required limit behaviour is effected following two different formulations, both developed on the grounds of a statical approach: the first one operates below the elastic shakedown limit and is able to provide a suboptimal design; the second one operates above the elastic shakedown limit and is able to provide the/an optimal design. The Kuhn–Tucker conditions of the two problems provide useful information about the different behaviour of the obtained structures.An application concludes the paper; the comparison among the designs is effected, pointing out the different behaviour of the obtained structures as well as the required computational effort related to the numerical solutions.     

Computational method for turbulent supersonic flows

The calculation features of the turbulent flows described by the Reynolds equations and the two-equation model of turbulence are examined for an explicit high-order accurate Godunov method. Under these features, a new version of a high order of Godunov’s method is developed for calculating the compressible turbulent flows. To illustrate the capability of the new method, some results of the calculation are shown for a supersonic turbulent jet with a complex shock-wave structure and for a separate flow in a plane nozzle.     

Computational method for the point cluster analysis on networks

We present a general framework of hierarchical methods for point cluster analysis on networks, and then consider individual clustering procedures and their time complexities defined by typical variants of distances between clusters. The distances considered here are the closest-pair distance, the farthest-pair distance, the average distance, the median-pair distance and the radius distance. This paper will offer a menu for users to choose hierarchical clustering algorithms on networks from a time complexity point of view.     

Computational methods for optimal shakedown design of FE structures

The paper concerns the optimal shakedown design of structures discretized by elastic perfectly plastic finite elements. The design problem is formulated in four alternative versions, i.e. as the search for the minimum volume design whose shakedown limit load multiplier is assigned or as the search for the maximum shakedown limit load multiplier design whose volume is assigned; both problems are approached on the grounds of the shakedown lower bound and upper bound theorems. Correspondingly four computational methods, one for each original problem, are presented. These methods consist in solving iteratively new problems which are simpler than the original ones, but expressed in such a way that the obtained design and behavioural variables fulfill the optimality conditions of the relevant original problems, and thus they provide the true optimal design. Finally, an alternative numerical approach devoted to obtaining the optimal shakedown design is presented. Several numerical examples confirm the theoretical results.     

Computational design of iris folding patterns

Computational Visual Media - Iris folding is an art-form consisting of layered strips of paper, forming a spiral pattern behind an aperture, which can be used to make cards and gift tags. This...     

Computational implementation of the polarization propagator method

A computational implementation of the polarization propagator method is outlined. The program is constructed so that, in principle, there are no limitations either on the size of the basis set or on the size of the particle-hole excitation space. The lists of two-electron integrals and propagator matrices are both assumed to be too large to be kept in primary storage. A list of symbolic matrix elements is generated and the individual terms which contribute to the matrix elements are reordered so that the list of two-electron integrals can be processed sequentially. Timings for the various steps of the program are given for CO₂ as a test case. It is shown that a major part of the computational effort goes into the construction of the B(2) matrix and that the CPU and I/O times are comparable.     

Computational steering of a multi-objective evolutionary algorithm for engineering design

The execution process of an evolutionary algorithm typically involves some trial and error. This is due to the difficulty in setting the initial parameters of the algorithm—especially when little is known about the problem domain. This problem is magnified when applied to many-objective optimisation, as care is needed to ensure that the final population of candidate solutions is representative of the trade-off surface. We propose a computational steering system that allows the engineer to interact with the optimisation routine during execution. This interaction can be as simple as monitoring the values of some parameters during the execution process, or could involve altering those parameters to influence the quality of the solutions produced by the optimisation process. The implementation of this steering system should provide the ability to tailor the client to the hardware available, for example providing a lightweight steering and visualisation client for use on a PDA.     

Computational performance of Huang's symmetric update for the conjugate gradient method

Summary The Huang's symmetric update for the conjugate gradient method in unconstrained function minimization is introduced and fundamental properties are reviewed. Criteria to choose the free parameters are given and a number of related algorithms, some considered for the first time, are studied on a set of test functions. Queste Note sono edite a cura del ?Gruppo AICA sugli Algoritmi?, coordinato da I. Galligani. Paper presented at the Conference on Numerical Analysis; held in Dublin, on August 14–18, 1972.     

Computational aspects of the stochastic finite element method

We present an overview of the stochastic finite element method with an emphasis on the computational tasks involved in its implementation.      

Computational science and scientific method

The process of constructing mathematical models is examined and a case made that the construction process is an integral part of the justification for the model. The role of heuristics in testing and modifying models is described and some consequences for scientific methodology are drawn out. Three different ways of constructing the same model are detailed to demonstrate the claims made here.     

细胞色素P450BM3蛋白质瞬时界面的计算设计研究

瞬时蛋白-蛋白作用在细胞内有着重要的生理作用,所形成的界面为瞬时蛋白-蛋白界面.作为电子传递功能相关瞬时界面的代表,细胞色素P450被广泛的研究.本文选取具有高效电子传递效率的P450BM3蛋白作为研究素材,在其HEME域上选择了9个设计位点.通过在能量函数中引入特异性能量函数项,取得了较好的设计结果,有6个位点的残基类型与天然蛋白的残基类型一致.另外,本文还探讨了计算模型中加入水分子的重要性,说明了水分子在提供范德华能和氢键能方面的作用.     

心式铁心柱电力变压器油道位置设计计算

利用电力变压器铁心柱制造特点,针对铁心柱内插入油道的要求将其转化为半径为R的圆内插入一族平行线,这族平行线分圆面积为相等的带状区域这一问题,然后用MATLAB中的SOLVE（）函数求解,从而得到了油道位置的准确数据,为变压器的设计制造提供了科学依据。     

Computational observer design techniques for linear systems withunknown inputs using the concept of transmission zeros

Computational observer design techniques for linear systems subject to unknown inputs are presented. Complete and intuitive geometric conditions for the solution of the problem which result in design matrix equations are provided. These design equations are solved in a computationally efficient way. The synthesis of the reduced-order observer takes full advantage of the concept of transmission zeros. In particular, the necessary and sufficient conditions obtained are given in terms of the transmission zeros of the triple (A,D, C)     

Algebraic method for the design of output deadbeat controller

Based on the deadbeat model approach and the technique of output spectra matching, an algebraic method for the design of an approximate deadbeat controller with a specified configuration has been proposed. The chosen controller is determined by solving a set of simultaneous algebraic equations. One example is given to show the characteristic features of this approach.     

Computational procedure for optimum shape design based on chained Bezier surfaces parameterization

Optimum design introduces strong emphasis on compact geometry parameterization in order to reduce the dimensionality of the search space and consequently optimization run-time. This paper develops a decision support system for optimum shape which integrates geometric knowledge acquisition using 3D scanning and evolutionary shape re-engineering by applying genetic-algorithm based optimum search within a distributed computing workflow.A shape knowledge representation and compaction method is developed by creating 2D and 3D parameterizations based on adaptive chaining of piecewise Bezier curves and surfaces. Low-degree patches are used with adaptive subdivision of the target domain, thereby preserving locality. C¹ inter-segment continuity is accomplished by generating additional control points without increasing the number of design variables. The control points positions are redistributed and compressed towards the sharp edges contained in the data-set for better representation of areas with sharp change in slopes and curvatures. The optimal decomposition of the points cloud or target surface into patches is based on the requested modeling accuracy, which works as lossy geometric data-set compression. The proposed method has advantages in non-recursive evaluation, possibility of chaining patches of different degrees, options of prescribing fixed values at selected intermediate points while maintaining C¹ continuity, and uncoupled processing of individual patches.The developed procedure executes external application nodes using mutual communication via native data files and data mining. This adaptive interdisciplinary workflow integrates different algorithms and programs (3D shape acquisition, representation of geometry with data-set compaction using parametric surfaces, geometric modeling, distributed evolutionary optimization) such that optimized shape solutions are synthesized. 2D and 3D test cases encompassing holes and sharp edges are provided to prove the capacity and respective performance of the developed parameterizations, and the resulting optimized shapes for different load cases demonstrate the functionality of the overall distributed workflow.     

A method for the design of binary tree classifiers

A method based on multivariate stepwise regression is proposed for the design of binary tree classifiers. Experimental results of cell classification are given to illustrate the efficiency of the proposed method.