Idealization and Theorems of D. D. Anderson

All rings are commutative with identity and all modules are unital. Anderson proved that a submodule N of an R-module M is multiplication (resp. join principal) if and only if 0₍₊₎ N is a multiplication (resp. join principal) ideal or R(M). The idealization of M. In this article we develop more fully the tool of idealization of a module, particularly in the context of multiplication modules, generalizing Anderson's theorems and discussing the behavior under idealization of some ideals and some submodules associated with a module.     

Coupling 3D and 1D Skeletal Muscle Models

This work introduces a modelling framework towards a forward dynamics simulation of skeletal muscle mechanics that couples three-dimensional (3D) continuum-mechanical-based Finite Element (FE) simulations to rigid body simulations. In this regard, this is a methodological approach, which incorporates different methods to realise simulations of the musculoskeletal system. Such simulations are at present computationally not feasible. To set up such a modelling framework the upper limp is selected. Here, the upper limb consists of an antagonistic muscle pair, the elbow (a simple hinge joint) and an external load. The skeletal muscles are represented by a 3D continuum-mechanical model. The tendons are, for now, assumed to be rigid. The results demonstrate the ability of the system to converge to a physiological realistic position. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Irreducible W-Graphs for Type D 4 and D 5

ABSTRACT

The “W-graph” concept was introduced by Kazhdan and Lusztig in their influential article Kazhdan and Lusztig (1979 Kazhdan , D. , Lusztig , G. ( 1979 ). Representations of Coxeter groups and Hecke algebras . Invent. Math. 53 : 165 – 184 . [CROSSREF] [CSA] [Crossref], [Web of Science ®] , [Google Scholar]). If W is a Coxeter group, then a W-graph provides a method for constructing a matrix representation of the Hecke algebra ? associated with W (the degree of the representation being the number of vertices of the W-graph). The aim of this note is to explicitly construct all the irreducible representations of ? when W is of type D ₄ and D ₅.     

Idealization and Theorems of D. D. Anderson II

In our recent work we investigated Anderson's theorems and gave a treatment of certain aspects of multiplication modules and cancellation-like modules via idealization. The purpose of this work is to continue our study and develop the tool of idealization of modules, particularly in the context of flat modules.     

Life,a modern and unified C++ implementation of finite-element and spectral-element methods in 1D, 2D and 3D

We present a brief overview of Life, a unified framework for finite element and spectral element methods in 1D, 2D and 3D in C ++. First, we describe some basic principles, then we focus on the two cornerstones of the library, the polynomial library and FEEL++, a C ++ embedded language designed for partial differential equations. The applications range is potentially quite large; at the moment Life is essentially used for the development of new numerical methods and the exhaustive comparisons between standard ones e.g. high order methods, stabilisation methods. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Numerical solution of 2D and 3D backward facing step flows

The work deals with numerical modelling of flow through 2-dimensional (2D) and 3-dimensional (3D) backward facing step. In laminar case, we apply several higher order upwind and central discretizations and compare numerical results with measurements. The turbulent regime is considered in 2D as well as in 3D and influence of secondary flow is observed. Different modifications of low-Re two equation turbulence models and an explicit algebraic Reynolds stress model (EARSM) are considered. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Composite schemes used for 2D and 3D transonic flows computation

This work deals with numerical solution of 3D inviscid transonic flows in a channel using finite volume form of composite scheme. The combination of less dissipative Lax‐Wendroffs cheme and more dissipative Lax‐Friedrichs scheme is used in cell‐vertex form and basic 3D five sides finite volume. Some 3D results of transonic flows in a channel that is an extension of 2D GAMM channel with a) a changed bump in z‐direction b) not changed bump but with swept wing geometry are presented in the article.     

Functor D and strong homotopy

This paper studies functor D and strong homotopy, introduced earlier by the author [1]. A theorem is proven on mappings, and the connection is established between the concepts of strong homotopy of DGA-mapping of coalgebras and functor D. As topological applications, in particular, it is shown that continuous mappings of the sphere f, g: S^2n–1Sⁿ have one and the same Hopf invariant if and only if the induced chain of mappings is strongly homotopic.Translated from Matematicheskie Zametki, Vol. 21, No. 4, pp. 557–564, April, 1977.     

Spectral controllability for 2D and 3D linear Schrödinger equations

We consider a quantum particle in an infinite square potential well of Rn, n=2,3, subjected to a control which is a uniform (in space) electric field. Under the dipolar moment approximation, the wave function solves a PDE of Schrödinger type. We study the spectral controllability in finite time of the linearized system around the ground state. We characterize one necessary condition for spectral controllability in finite time: (Kal) if Ω is the bottom of the well, then for every eigenvalue λ of , the projections of the dipolar moment onto every (normalized) eigenvector associated to λ are linearly independent in Rn. In 3D, our main result states that spectral controllability in finite time never holds for one-directional dipolar moment. The proof uses classical results from trigonometric moment theory and properties about the set of zeros of entire functions. In 2D, we first prove the existence of a minimal time Tmin(Ω)>0 for spectral controllability, i.e., if T>Tmin(Ω), one has spectral controllability in time T if condition (Kal) holds true for (Ω) and, if T<Tmin(Ω) and the dipolar moment is one-directional, then one does not have spectral controllability in time T. We next characterize a necessary and sufficient condition on the dipolar moment insuring that spectral controllability in time T>Tmin(Ω) holds generically with respect to the domain. The proof relies on shape differentiation and a careful study of Dirichlet-to-Neumann operators associated to certain Helmholtz equations. We also show that one can recover exact controllability in abstract spaces from this 2D spectral controllability, by adapting a classical variational argument from control theory.     

The strain-rate-dependent material and failure behaviour of 2D and 3D non-crimp glass-fibre-reinforced composites

For a reliable structural design of security-relevant, high-dynamically loaded light weight structures, the knowledge of the strain-rate-dependent material and damage behaviour, material properties, and validated material models have to be provided. For this purpose, various material tests at different strain rates have been performed on composites with a novel 3D-reinforced glass-fibre multilayered flat-bed weft-knitted fabric reinforcement by using a servohydraulic high-speed testing unit in combination with specially adapted clamping de vices. The highly dynamic material tests served to develop adequate material models in the classical sense of continuum damage mechanics and to determine the associated model parameters.     

Coupling 3D and 1D fluid-structure interaction models for blood flow simulations

Three-dimensional (3D) simulations of blood flow in medium to large vessels are now a common practice. These models consist of the 3D Navier-Stokes equations for incompressible Newtonian fluids coupled with a model for the vessel wall structure. However, it is still computationally unaffordable to simulate very large sections, let alone the whole, of the human circulatory system with fully 3D fluid-structure interaction models. Thus truncated 3D regions have to be considered. Reduced models, one-dimensional (1D) or zero-dimensional (0D), can be used to approximate the remaining parts of the cardiovascular system at a low computational cost. These models have a lower level of accuracy, since they describe the evolution of averaged quantities, nevertheless they provide useful information which can be fed to the more complex model. More precisely, the 1D models describe the wave propagation nature of blood flow and coupled with the 3D models can act also as absorbing boundary conditions. We consider in this work the coupling of a 3D fluid-structure interaction model with a 1D hyperbolic model. We study the stability of the coupling and present some numerical results. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Classification of Curves in 2D and 3D via Affine Integral Signatures

We propose new robust classification algorithms for planar and spatial curves subjected to affine transformations. Our motivation comes from the problems in computer image recognition. To each planar or spatial curve, we assign a planar signature curve. Curves, equivalent under an affine transformation, have the same signature. The signatures are based on integral invariants, which are significantly less sensitive to small perturbations of curves and noise than classically known differential invariants. Affine invariants are derived in terms of Euclidean invariants. We present two types of signatures: the global and the local signature. Both signatures are independent of curve parameterization. The global signature depends on a choice of the initial point and, therefore, cannot be used for local comparison. The local signature, albeit being slightly more sensitive to noise, is independent of the choice of the initial point and can be used to solve local equivalence problem. An experiment that illustrates robustness of the proposed signatures is presented.     

Comparative study of 1D, 2D and 3D simplified gas kinetic schemes for simulation of inviscid compressible flows

With assumption that all the particles in the phase velocity space are concentrated on a circle and on a sphere, the circular function-based gas kinetic scheme and sphere function-based gas kinetic scheme have been developed by Shu and his coworkers [21], [22], [23]. These schemes are simpler than the Maxwellian function-based gas kinetic schemes. The simplicity is due to the fact that the integral domain of phase velocity of circular function and sphere function is a finite region while the integral domain of Maxwellian distribution function is infinite. In this work, the 1D delta function-based gas kinetic scheme is also developed to form a complete set of the simplified gas kinetic schemes. The 1D, 2D and 3D simplified gas kinetic schemes can be viewed as the truly 1D, 2D and 3D flux solvers since they are based on the multi-dimensional Boltzmann equation. On the other hand, to solve the 3D flow problem, the tangential velocities are needed to be approximated by some ways for the 1D and 2D simplified gas kinetic schemes, and to solve the 1D flow problem, the tangential velocities should be taken as zero for the 2D and 3D simplified gas kinetic schemes. The performances of these three schemes for simulation of inviscid compressible flows are investigated in this work by their application to solve the test problems from 1D to 3D cases. Numerical results showed that the efficiency of the delta function-based gas kinetic scheme is slightly superior to that of the circular function- and sphere function-based gas kinetic schemes, while its stability is inferior significantly to the latter. For simulation of the 3D hypersonic flows, the sphere function-based gas kinetic scheme could be the best choice.     

Optimal and adaptive control for a kind of 3D chaotic and 4D hyper-chaotic systems

This paper is concerned with the chaos control of two autonomous chaotic and hyper-chaotic systems. First, based on the Pontryagin minimum principle (PMP), an optimal control technique is presented. Next, we proposed Lyapunov stability to control of the autonomous chaotic and hyper-chaotic systems with unknown parameters by a feedback control approach. Matlab bvp4c and ode45 have been used for solving the autonomous chaotic systems and the extreme conditions obtained from the PMP. Numerical simulations on the chaotic and hyper-chaotic systems are illustrated to show the effectiveness of the analytical results.     

Solving 2D and 3D Poisson equations and biharmonic equations by the Haar wavelet method

In this paper, we present a computational method for solving 2D and 3D Poisson equations and biharmonic equations which based on the use of Haar wavelets. The highest derivative appearing in the differential equation is expanded into the Haar series, this approximation is integrated while the boundary conditions are incorporated by using integration constants. In 2D the first transform the spectral coefficients into the nodal variable values and then use Kronecker products to construct the approximations for derivatives over a tensor product grid of the horizontal and vertical blocks. Finally, solutions to four test problems are investigated.     

T D property and spatial sublocales

As one of main backgrounds of locale theory, topologies have close connections with locales. But locales have other backgrounds such as algebra, mathematical logic, etc. So there are many differences between locales and topologies. Spatiality is an important localic property to investigate the connections between locales and topologies. TheT _D property is a special separation property which plays an important role in this kind of investigations. Just as it will be proved in this paper, theT _D property often appears as the lowest requirement for many topological spaces such that they can be described with localic properties and vice versa. In this paper, we show these special properties of theT _D axiom and investigate some other interesting and important problems ofT _D -spatiality of locales.Supported by the National Natural Science Foundation of China and the Science Foundation of the State Education Commision of China.Supported by the Fund for Excellent Young University Teachers of the State Educational Commission of China and theE _x -Oversea-Scholars Fund of the Educational Commission of China.     

Learning-based robust stabilization for reduced-order models of 2D and 3D Boussinesq equations

We present some results on the stabilization of reduced-order models (ROMs) for thermal fluids. The stabilization is achieved using robust Lyapunov control theory to design a new closure model that is robust to parametric uncertainties. Furthermore, the free parameters in the proposed ROM stabilization method are optimized using a data-driven multi-parametric extremum seeking (MES) algorithm. The 2D and 3D Boussinesq equations provide challenging numerical test cases that are used to demonstrate the advantages of the proposed method.     

Relations between directional derivatives for smooth functions in 2D and 3D spaces

In this paper, relations between directional derivatives are considered for smooth functions both in 2D and 3D spaces. These relations are established in the form of linear combinations of directional derivatives with their coefficients having simple form and structural regularity. By them, expressions based on directional derivatives for some typical differential operators are derived. This builds up a solid mathematical foundation for further study on numerical computation by the finite point method based on directional difference.     

3D Euler spirals for 3D curve completion

Shape completion is an intriguing problem in geometry processing with applications in CAD and graphics. This paper defines a new type of 3D curve, which can be utilized for curve completion. It can be considered as the extension to three dimensions of the 2D Euler spiral. We prove several properties of this curve - properties that have been shown to be important for the appeal of curves. We illustrate its utility in two applications. The first is “fixing” curves detected by algorithms for edge detection on surfaces. The second is shape illustration in archaeology, where the user would like to draw curves that are missing due to the incompleteness of the input model.