Comments on "On the inverses of certain matrices"

It is shown here that the method suggested by Chidambara (Barlett's equation) is a particular version of the general matrix modification formula[A + USV^{T}]^{-1} = A^{-1} - A^{-1}U[S^{-1}+ V^{T}A^{-1}U]^{-1}V^{T}A^{-1}and that the modification suggested by Chidambara is obtained from this general form.     

Comments on "Numerical application of Szegós method for constructing Liapunov functions"

It is pointed out that the algorithmic method recently suggested by Hewit and Storey for the construction of Lyapunov functions yields a result which is expressible in closed form.     

Comments on: "Robust line fitting in a noisy image by the method of moments"

Qjidaa and Radouane (1999) presented a method for robust line fitting and experimentally compared it to other methods, including a method suggested by us. The results attributed by Qjidaa and Radouane to our algorithm are incorrect. We apply our algorithm to the data used by Qjidaa and Radouane and demonstrate its robustness and accuracy.     

A decomposition technique for an optimal control problem with "PQDZ" cost and bounded controls

In this note we present a solution method for a discrete-time linear optimal control problem where the controls are bounded and both the states and controls have asymmetric costs with dead zones containing the nominal values. This model generalizes the well-known optimal control model for a linear system with symmetric (quadratic) objective functional. We transform the problem into an equivalent large quadratic programming problem with equality and inequality, constraints and decompose it intoNsimpler subproblems, each with very easily computed optimal solutions. Using a two-level approach suggested by Lasdon and Schoeffler [11] the optimal solution to the overall problem is obtained.     

Correction to "Elimination of singular cases in Jurýs test"

The purpose of this correspondence is to show that in certain situations the modification suggested in the above correspondence does not give the correct root distribution and fails to eliminate the singular case. Consequently, the correct modification which can handle these situations also is suggested. Incidentally, an incorrect statement made in the above correspondence is also pointed out.     

Comments on "On blocking zeros in linear multivariable systems"

It is suggested that the name "blocking zeros" in the above technical note is not appropriate and should be changed in order to avoid confusion in the literature.     

Comments on "Comments on the Routh-Hurwitz criterion"

It is shown that the algorithm given by Shamash for determining the number of roots of polynomial in the right half plane via the Routh table in the presence of purely imaginary roots and a left column zero is not complete and can give erroneous results. Modification for getting correct results is suggested.     

Comments on "The design of linear regulators optimal for time multiplied performance indices"

A procedure for the design of linear regulators optimal with respect to a time-multiplied performance index was suggested in a recent paper by Man and Smith. A counterexample, presented subsequently [2], indicated that the procedure was in error. It is shown that the optimal feedback control law must contain time-varying gains as opposed to the time-invariant gains as suggested by Man and Smith. This fact was also overlooked in [2].     

C1 continuous h-adaptive least-squares spectral element method for phase-field models

To describe the interfacial dynamics between two phases using the phase-field method, the interfacial region needs to be close enough to a sharp interface so as to reproduce the correct physics. Due to the high gradients of the solution within the interfacial region and consequent high computational cost, the use of the phase-field method has been limited to the small-scale problems whose characteristic length is similar to the interfacial thickness. By using finer mesh at the interface and coarser mesh in the rest of computational domain, the phase-field methods can handle larger scale of problems with realistic interface thicknesses. In this work, a $C^1$ continuous $h$-adaptive mesh refinement technique with the least-squares spectral element method is presented. It is applied to the Navier–Stokes-Cahn–Hilliard (NSCH) system and the isothermal Navier–Stokes–Korteweg (NSK) system. Hermite polynomials are used to give global differentiability in the approximated solution, and a space–time coupled formulation and the element-by-element technique are implemented. Two refinement strategies based on the solution gradient and the local error estimators are suggested, and they are compared in two numerical examples.     

Comments on "Cooperative games and vector-valued criteria problems"

A theorem in the above paper,[1] giving sufficient conditions for the local Pareto optimality, is shown to be incorrect by a counter-example and a revision of its proof. Moreover, an alternative formulation of this theorem is suggested.     

Comments on an approximation coefficient proposed in "Stochastic model simplification"

It is pointed out that the approximation coefficient defined in the above paper does not always satisfy the claimed properties. An alternative definition is suggested.     

Comments on "New techniques for the design of observers"

This note is to point out that by fully using the freedom of the observer equation rather than the arbitrary choice suggested in the paper, significantly better results can be derived with applications and solutions to many important problems.     

Comments on "Linear function observer for linear discrete-time systems"

Two alternative systematic algorithms are suggested to compute the matrixTnecessary to design a minimum-time linear function observer. The simplicity of these algorithms gives mole insight to the understanding of the observer structure. Furthermore, the computational effort required to obtain the matrixJis spared.     

Comments on "A fuzzy approach to strategic games"

A fuzzy approach was proposed in the above paper for the solution of strategic games and some useful conclusions were presented on the selection of optimal strategies in the prisoner's dilemma game. In this paper, a general result is presented for the case in which a prisoner is noncooperative and selfish, which makes the evaluation suggested in the above paper redundant in this case.     

Finite-size modelling of electrodes for quantum transport calculations using k-space ab initio techniques

We present an efficient and easy-to-use numerical treatment to check the necessary size of metallic leads with respect to their quantum-transport properties. The suggested method works entirely in k-space and avoids complicated projections of ab initio band structures onto real-space tight-binding-like Hamiltonians. As an illustrative example, we apply the method to various low-dimensional Au chains and discuss our DFT-based studies with respect to convergence speed and relevance of structural relaxation.     

Comments on "Application of 0-1 integer programming to multitarget tracking problems"

A change of notation is suggested to clarify results reported in [1]. It is noted that the proposed cost function is generally not linear. Thus, the 0-1 integer programming formulation is inappropriate without additional assumptions.     

Comments on "Direct adaptive fuzzy-neural control with state observer and supervisory controller for unknown nonlinear dynamical systems"

Some drawbacks of the aforementioned paper are pointed out, and a new direct adaptive fuzzy control algorithm is suggested for unknown nonlinear systems.     

吉祥物教学的新思考

随着科技和文化的飞速发展,时代又赋予了它新的概念和意义,所以对于"吉祥物设计"这门课程的教学需要有一个新的、整体的安排。该课程应该单列出来,通过理论与实践,了解吉祥物的开发和系列运用的各种形式和特点,并用多种表现方法和设计技巧让学生在作业训练中去体会。     

Additional comments on "Aggregation matrix for the reduced-order continued fraction expansion model of Chen and Shieh"

In the above paper the authors claim to have constructed an aggregation matrix equivalent to the continued fraction expansion model reduction technique of Chen and Shieh. It is shown that the suggested procedure is not equivalent and the correct version is given.