Lattices Research Papers - Academia.edu (original) (raw)

• Develop LBM performance to simulate the heat flux of heat source. • Natural convection and mixed convection of inclined driven cavity by LBM. • Modify collision operator and macroscopic velocities equations in LBM. a b s t r a c t Nano... more

• Develop LBM performance to simulate the heat flux of heat source. • Natural convection and mixed convection of inclined driven cavity by LBM. • Modify collision operator and macroscopic velocities equations in LBM. a b s t r a c t Nano scale method of lattice Boltzmann is developed to predict the fluid flow and heat transfer of air through the inclined lid driven 2-D cavity while a large heat source is considered inside it. Two case studies are supposed: first one is a pure natural convection at Grashof number from 400 to 4000 000 and second one is a mixed convection at Richardson number from 0.1 to 10 at various cavity inclination angles. Using LBM to simulate the constant heat flux boundary condition along the obstacle, is presented for the first time while the buoyancy forces affect the velocity components at each inclination angle; hence the collision operator of LBM and also a way to estimate the macroscopic velocities should be modified. Results are shown in the terms of streamlines and isotherms, beside the profiles of velocity, temperature and Nusselt number. It is observed that the present model of LBM is appropriately able to simulate the supposed domain. Moreover, the effects of inclination angle are more important at higher values of Richardson number.

We explore the lattice sphere packing representation of a multi-antenna system and the algebraic space-time (ST) codes. We apply the sphere decoding (SD) algorithm to the resulted lattice code. For the uncoded system, SD yields, with... more

We explore the lattice sphere packing representation of a multi-antenna system and the algebraic space-time (ST) codes. We apply the sphere decoding (SD) algorithm to the resulted lattice code. For the uncoded system, SD yields, with small increase in complexity, a huge improvement over the well-known V-BLAST detection algorithm. SD of algebraic ST codes exploits the full diversity of the coded multi-antenna system, and makes the proposed scheme very appealing to take advantage of the richness of the multi-antenna environment. The fact that the SD does not depend on the constellation size, gives rise to systems with very high spectral efficiency, maximum-likelihood performance, and low decoding complexity.

The basis for a theory of porous electrodes is the percolation problem. Its solution would make it possible to answer the question of how effectively the structure of a porous electrode is used for ensuring the occurrence of... more

The basis for a theory of porous electrodes is the percolation problem. Its solution would make it possible to answer the question of how effectively the structure of a porous electrode is used for ensuring the occurrence of electrochemical processes on its inner surface, for bringing together all its participants (reagents, ions, electrons, catalyst particles), and for removing the formed products. For the solution of this problem, it is necessary that both the elements of the structure of a porous electrode and the substances filling it should be connected. In the case of hydrophobized electrodes, these are exemplified by a mixture of agglomerated grains of polytetrafluoroethylene and catalyst, the gaseous reagent entering the electrons, and the electrolyte. In this publication, we describe a general method intended for the calculation of thresholds and lines of percolation and present particular estimates for an important class of lattices modeling porous media – rectangular: plane, square lattice, three-dimensional cubic, and their analogues in space of any number of measurements.

Lattice structure offers the potential to produce desirable macro-scale material properties for a wide variety of engineering applications including blast and impact protection system, thermal insulation, structural aircraft and vehicle... more

Lattice structure offers the potential to produce desirable macro-scale material properties for a wide variety of engineering applications including blast and impact protection system, thermal insulation, structural aircraft and vehicle components body implants. The work presented here to study the characteristics of quasistatic and dynamic behaviour of lattice structure of different materials. Initially cuboidal lattice structures were investigated to study the stress-strain response, failure behaviour and energy absorbing capacity. Drop hammer test were carried out to understand the behaviour of lattice structures under dynamic behaviour. The results obtained shows quasistatic tests are agreeable with dynamic tests.

Nanothermodynamics is an extension of usual thermodynamics, which deals with the systems consisting of finite particles. In other words, the study of sufficiently small systems at equilibrium requires a modification of ordinary... more

Nanothermodynamics is an extension of usual thermodynamics, which deals with the systems consisting of finite particles. In other words, the study of sufficiently small systems at equilibrium requires a modification of ordinary macroscopic thermodynamics. In this note, we solve two mathematical problems related to this area of since and technology.

This article discusses the figures of Llull’s Art and their interpretation in the light of mathematical models. Some points are cleared up concerning the use of graph theory, which is now also extended into that of hipergraphs and... more

This article discusses the figures of Llull’s Art and their interpretation in the light of mathematical models. Some points are cleared up concerning the use of graph theory, which is now also extended into that of hipergraphs and lattices, this last in connection with the Elemental Figure. Trees and the figures of the Book of Contemplation are not included, since they will be treated in forthcoming articles. Finally, the figures of the Art are presented as an example of what in modern science, technology and business administration is called diagrammatic reasoning.

An important computational problem in color imaging is the design of color transforms that map color between devices or from a device-dependent space (e.g., RGB/CMYK) to a device-independent space (e.g., CIELAB) and vice versa. Real-time... more

An important computational problem in color imaging is the design of color transforms that map color between devices or from a device-dependent space (e.g., RGB/CMYK) to a device-independent space (e.g., CIELAB) and vice versa. Real-time processing constraints entail that such nonlinear color transforms be implemented using multidimensional lookup tables (LUTs). Furthermore, relatively sparse LUTs (with efficient interpolation) are employed in practice because of storage and memory constraints. This paper presents a principled design methodology rooted in constrained convex optimization to design color LUTs on a simplex topology. The use of n simplexes, i.e., simplexes in n dimensions, as opposed to traditional lattices, recently has been of great interest in color LUT design for simplex topologies that allow both more analytically tractable formulations and greater efficiency in the LUT. In this framework of n-simplex interpolation, our central contribution is to develop an elegant iterative algorithm that jointly optimizes the placement of nodes of the color LUT and the output values at those nodes to minimize interpolation error in an expected sense. This is in contrast to existing work, which exclusively designs either node locations or the output values. We also develop new analytical results for the problem of node location optimization, which reduces to constrained optimization of a large but sparse interpolation matrix in our framework. We evaluate our n -simplex color LUTs against the state-of-the-art lattice (e.g., International Color Consortium profiles) and simplex-based techniques for approximating two representative multidimensional color transforms that characterize a CMYK xerographic printer and an RGB scanner, respectively. The results show that color LUTs designed on simplexes offer very significant benefits over traditional lattice-based alternatives in improving color transform accuracy even with a much smaller number- of nodes.

This paper discusses the possibility of manufacturing the intermediate band solar cell (IBSC), a cell with the potential of achieving 63.2% of efficiency under concentrated sunlight, using quantum dot technology. The 0-dimensionality... more

This paper discusses the possibility of manufacturing the intermediate band solar cell (IBSC), a cell with the potential of achieving 63.2% of efficiency under concentrated sunlight, using quantum dot technology. The 0-dimensionality nature of the dots avoids electron thermalisation between bands enhancing the possibilities for radiative recombination between bands and making possible the existence of three quasi-fermi levels, some of the pivots the theory of the IBSC is sustained on. In this sense, it is suggested that an InGaAs/AlGaAs system could be used for band engineering the optimum bandgaps of the IBSC cell (0.71 and 1.24 eV). Dots should be about 40 Å of radius, spaced in the range of 100 Å and distributed in a three dimensional array. The Stranski and Krastanow method is proposed as a technology for achieving this goal. The possibility of n-doping the dots is also discussed

Building a composite application based on Web services has become a real challenge regarding the large and diverse service space nowadays. Especially when considering the various functional and non-functional capabilities that Web... more

Building a composite application based on Web services has become a real challenge regarding the large and diverse service space nowadays. Especially when considering the various functional and non-functional capabilities that Web services may afford and users may require. In this paper, we propose an approach for facilitating Web service selection according to user requirements. These requirements specify the needed functionality and expected QoS, as well as the composability between each pair of services. The originality of our approach is embodied in the use of Relational Concept Analysis (RCA), an extension of Formal Concept Analysis (FCA). Using RCA, we classify services by their calculated QoS levels and composability modes. We use a real case study of 901 services to show how to accomplish an efficient selection of services satisfying a specified set of functional and non-functional requirements.

A lattice structure for an M-channel linear-phase perfect reconstruction filter bank (LPPRFB) based on the singular value decomposition (SVD) is introduced. The lattice can be proven to use a minimal number of delay elements and to... more

A lattice structure for an M-channel linear-phase perfect reconstruction filter bank (LPPRFB) based on the singular value decomposition (SVD) is introduced. The lattice can be proven to use a minimal number of delay elements and to completely span a large class of LPPRFBs: all analysis and synthesis filters have the same FIR length, sharing the same center of symmetry. The lattice also structurally enforces both linear-phase and perfect reconstruction properties, is capable of providing fast and efficient implementation, and avoids the costly matrix inversion problem in the optimization process. From a block transform perspective, the new lattice can be viewed as representing a family of generalized lapped biorthogonal transform (GLBT) with an arbitrary number of channels M and arbitrarily large overlap. The relaxation of the orthogonal constraint allows the GLBT to have significantly different analysis and synthesis basis functions, which can then be tailored appropriately to fit a particular application. Several design examples are presented along with a high-performance GLBT-based progressive image coder to demonstrate the potential of the new transforms

Introduces a new image coding scheme using lattice vector quantization. The proposed method involves two steps: biorthogonal wavelet transform of the image, and lattice vector quantization of wavelet coefficients. In order to obtain a... more

Introduces a new image coding scheme using lattice vector quantization. The proposed method involves two steps: biorthogonal wavelet transform of the image, and lattice vector quantization of wavelet coefficients. In order to obtain a compromise between minimum distortion and bit rate, we must truncate and scale the lattice suitably. To meet this goal, we need to know how many lattice points lie within the truncated area. We investigate the case of Laplacian sources where surfaces of equal probability are spheres for the L1 metric (pyramids) for arbitrary lattices. We give explicit generating functions for the codebook sizes for the most useful lattices like Zn, Dn, Es, ∧16

We study concept lattices with hedges. The principal aim is to control, in a parametrical way, the size of a concept lattice. The paper presents theoretical insight, comments, and examples. We show that a concept lattice with hedges is... more

We study concept lattices with hedges. The principal aim is to control, in a parametrical way, the size of a concept lattice. The paper presents theoretical insight, comments, and examples. We show that a concept lattice with hedges is indeed a complete lattice which is isomorphic to an ordinary concept lattice. We describe the isomorphism and its inverse. These mappings serve as translation procedures. As a consequence, we obtain a theorem characterizing the structure of concept lattices with hedges which generalizes the so-called main theorem of concept lattices. Furthermore, the isomorphism and its inverse enable us to compute a concept lattice with hedges using algorithms for ordinary concept lattices. Further insight is provided in case one uses hedges only for attributes. We demonstrate by experiments that the size reduction using hedges as a parameter is smooth

The eect of stochasticity in mechanical behaviour of metamaterials is quantied in a probabilistic framework. The stochasticity has been accounted in the form of random material distribution and structural irregularity, which are often... more

The eect of stochasticity in mechanical behaviour of metamaterials is quantied in a probabilistic framework. The stochasticity has been accounted in the form of random material distribution and structural irregularity, which are often encountered due to manufacturing and operational uncertainties. An analytical framework has been developed for analysing the eective stochastic in-plane elastic properties of irregular hexagonal structural forms with spatially random variations of cell angles and intrinsic material properties. Probabilistic distributions of the in-plane elastic moduli have been presented considering both randomly homogeneous and randomly inhomogeneous stochasticity in the system, followed by an insightful comparative discussion. The ergodic behaviour in spatially irregular lattices is investigated as a part of this study. It is found that the eect of random micro-structural variability in structural and material distribution has considerable inuence on mechanical behaviour of metamaterials.

The thermal drift of the characteristic wavelength of fiber Bragg gratings (FBGs) photowritten in the core of microstructured fibers (MOFs) is significantly reduced by inserting a liquid of suitable refractive index into their holes. For... more

The thermal drift of the characteristic wavelength of fiber Bragg gratings (FBGs) photowritten in the core of microstructured fibers (MOFs) is significantly reduced by inserting a liquid of suitable refractive index into their holes. For instance, the spectral range of variations is divided by a factor of 4 over a temperature range larger than 20\degree C in a six-hole MOF, and the maximum sensitivity is reduced. Such passive FBG temperature compensation technique is of great interest for applications involving accurate sensing free of thermal effects.