678 research outputs found
Recent Progress in Shearlet Theory: Systematic Construction of Shearlet Dilation Groups, Characterization of Wavefront Sets, and New Embeddings
The class of generalized shearlet dilation groups has recently been developed
to allow the unified treatment of various shearlet groups and associated
shearlet transforms that had previously been studied on a case-by-case basis.
We consider several aspects of these groups: First, their systematic
construction from associative algebras, secondly, their suitability for the
characterization of wavefront sets, and finally, the question of constructing
embeddings into the symplectic group in a way that intertwines the
quasi-regular representation with the metaplectic one. For all questions, it is
possible to treat the full class of generalized shearlet groups in a
comprehensive and unified way, thus generalizing known results to an infinity
of new cases. Our presentation emphasizes the interplay between the algebraic
structure underlying the construction of the shearlet dilation groups, the
geometric properties of the dual action, and the analytic properties of the
associated shearlet transforms.Comment: 28 page
Экономическая целесообразность прогнозирования брака по параметру биения
Для выбора экономически целесообразного применения технологий обработки и сборки предлагается учитывать величину прогнозированного брака по параметру биения.For the choice economic expedient application of technologies of treatment and assembling the method of prognostication of marriage is offered on the parameter of beating
A Probabilistic proof of the breakdown of Besov regularity in -shaped domains
{We provide a probabilistic approach in order to investigate the smoothness
of the solution to the Poisson and Dirichlet problems in -shaped domains. In
particular, we obtain (probabilistic) integral representations for the
solution. We also recover Grisvard's classic result on the angle-dependent
breakdown of the regularity of the solution measured in a Besov scale
Value and Use of Artificial Insemination by Beef Producers
Artificial insemination and estrous synchronization remain underutilized by U.S. beef producers. The most recent National Animal Health Monitoring Survey (NAHMS 2007–08) reported that 7.6% of producers used artificial insemination and 7.9% used estrous synchronization. The most common reason cited for not using these reproductive technologies was time and labor, followed by cost and difficulty. Little information is available on actual management practices used by producers who do use these technologies and their value to such operations
Distillation column dynamics and control
A pilot plant scale, atmospheric pressure, sieve plate distillation column was constructed and fully instrumented. Novel speed controllable pumps were used to control liquid flows. A microcomputer was constructed to provide local and hierarchical control of the column. The microcomputer included an operator console, a 16 channel data acquisition unit, a 4 channel control output unit, and a hardware arithmetic processor. A software development system was assembled by linking the microcomputer to a minicomputer. Software written for the development system included a cross-assembler, a transfer program, and a microcomputer control program. A binary steady state distillation column model was developed, solved on a digital computer, and verified against experimental data using a binary mixture of methanol and water.
Two control schemes were investigated using only the microcomputer resources. A multi-loop system using digital PI controllers was found to give excellent control within the accuracy of the instrumentation.
An adaptive feedforward controller was proposed and verified using a steady state model, and experiments. The results were good, but because of the relatively simple dynamics of the experimental column, the feedforward controller was no better than the feedback controllers.
A microcomputer control system has been shown to be an effective replacement for conventional analog control on a distillation column. The computing power of the microcomputer has enabled a sophisticated control scheme to be implemented at low cost
Accelerated Projected Gradient Method for Linear Inverse Problems with Sparsity Constraints
Regularization of ill-posed linear inverse problems via penalization
has been proposed for cases where the solution is known to be (almost) sparse.
One way to obtain the minimizer of such an penalized functional is via
an iterative soft-thresholding algorithm. We propose an alternative
implementation to -constraints, using a gradient method, with
projection on -balls. The corresponding algorithm uses again iterative
soft-thresholding, now with a variable thresholding parameter. We also propose
accelerated versions of this iterative method, using ingredients of the
(linear) steepest descent method. We prove convergence in norm for one of these
projected gradient methods, without and with acceleration.Comment: 24 pages, 5 figures. v2: added reference, some amendments, 27 page
Induced Crystallization of Polyelectrolyte-Surfactant Complexes at the Gas-Water Interface
Synchrotron-X-ray and surface tension studies of a strong polyelectrolyte
(PE) in the semi-dilute regime (~ 0.1M monomer-charges) with varying surfactant
concentrations show that minute surfactant concentrations induce the formation
of a PE-surfactant complex at the gas/solution interface. X-ray reflectivity
and grazing angle X-ray diffraction (GIXD) provide detailed information of the
top most layer, where it is found that the surfactant forms a two-dimensional
liquid-like monolayer, with a noticeable disruption of the structure of water
at the interface. With the addition of salt (NaCl) columnar-crystals with
distorted-hexagonal symmetry are formed.Comment: 4 pages, 5 eps figure
A wavelet based numerical method for nonlinear partial differential equations
The purpose of this paper is to present a wavelet–Galerkin scheme for solving
nonlinear elliptic partial differential equations. We select as trial spaces a nested
sequence of spaces from an appropriate biorthogonal multiscale analysis. This gives
rise to a nonlinear discretized system. To overcome the problems of nonlinearity, we
apply the machinery of interpolating wavelets to obtain knot oriented quadrature
rules. Finally, Newton’s method is applied to approximate the solution in the given
ansatz space. The results of some numerical experiments with different biorthogonal
systems, confirming the applicability of our scheme, are presented.Instituto de Cooperação Científica e Tecnológica Internacional - Acções Integradas Luso-Alemãs (DAAD/ICCTI) - Projecto DAAD/ICCTI nº 01141
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