Learning-Based Fast Iterative Convergence of 3-D MoM via Eigen-AGMRES Method

Three-dimensional (3-D) full-wave electromagnetic simulation using method of moments (MoM) under the framework of fast solver algorithms like fast multipole method (FMM) is often bottlenecked by the speed of convergence of the Krylov-subspace-based iterative process. This is primarily because the electric field integral equation (EFIE) matrix, even with cutting-edge preconditioning techniques, often exhibits bad spectral properties arising from frequency or geometry-based ill-conditioning, which render iterative solvers slow to converge or stagnate occasionally. In this communication, a novel technique to expedite the convergence of MoMmatrix solution at a specific frequency is proposed, by extracting and applying Eigen-vectors from a previously solved neighboring frequency in an augmented generalized minimum residual (AGMRES) iterative framework. This technique can be applied in unison with any preconditioner. Numerical results demonstrate up to 40% speed-up in convergence using the proposed Eigen-AGMRES method.

Thermal Strain Analysis of a Flip-Chip Package by a Modified Hybrid Method

介绍一种可用于微电子封装局部应变场分析的实验/计算混合方法,该方法结合了有限元的整体/局部模型和实时的激光云纹干涉技术,利用激光云纹干涉技术所测得的应变场来校核有限元整体模型的计算结果,并用整体模型的结果作为局部模型的边界条件,对实验难以确定的封装结构局部位置的应力、应变场进行分析.用这种方法对可控坍塌倒装封装结构在热载荷作用下焊球内的应变场分布进行了分析,结果表明该方法能够提供封装结构内应力-应变场分布的准确和可靠的结果,为微电子封装的可靠性分析提供重要的依据. For the reliability analysis of electronic packages, strains in very localized areas, such as an interconnection or a corner, need to be determined. In this paper, a modified hybrid method of global/local modeling and real time moire interferometry is presented. In this method, a simplified, coarsely meshed global model is developed to get rough information about the deformation of the microelectronic package. In order to make sure the global model has been reasonably simplified and the material properties ...

An improvement and proof of OGY method

OGY method is the most important method of controlling chaos. It stabilizes a hyperbolic periodic orbit by making small perturbations for a system parameter. This paper improves the method of choosing parameter, and gives a mathematics proof of it.

Domain decomposition hybrid method for numerical simulation of bluff body flows:theoretical model and application

The discrete vortex method is not capable of precisely predicting the bluff body flow separation and the fine structure of flow field in the vicinity of the body surface. In order to make a theoretical improvement over the method and to reduce the difficulty in finite-difference solution of N-S equations at high Reynolds number, in the present paper, we suggest a new numerical simulation model and a theoretical method for domain decomposition hybrid combination of finite-difference method and vortex method. Specifically, the full flow. field is decomposed into two domains. In the region of O(R) near the body surface (R is the characteristic dimension of body), we use the finite-difference method to solve the N-S equations and in the exterior domain, we take the Lagrange-Euler vortex method. The connection and coupling conditions for flow in the two domains are established. The specific numerical scheme of this theoretical model is given. As a preliminary application, some numerical simulations for flows at Re=100 and Re-1000 about a circular cylinder are made, and compared with the finite-difference solution of N-S equations for full flow field and experimental results, and the stability of the solution against the change of the interface between the two domains is examined. The results show that the method of the present paper has the advantage of finite-difference solution for N-S equations in precisely predicting the fine structure of flow field, as well as the advantage of vortex method in efficiently computing the global characteristics of the separated flow. It saves computer time and reduces the amount of computation, as compared with pure N-S equation solution. The present method can be used for numerical simulation of bluff body flow at high Reynolds number and would exhibit even greater merit in that case.

A Method for siting and prioritizing the removal of derelict vessels in Florida Coastal Waters: test applications in the Florida Keys

Increased boating activities and new waterfront developments have contributed an estimated 3,000 dismantled, abandoned, junked, wrecked, derelict vessels to Florida coastal waters. This report outlines a method of siting and prioritizing derelict vessel removal using the Florida Keys as a test area. The data base was information on 240 vessels, obtained from Florida Marine Patrol files. Vessel location was plotted on 1:250,000 regional and 1:5,000 and 1:12,000 site maps. Type of vessel, length, hull material, engine, fuel tanks, overall condition, afloat and submerged characteristics, and accessibility, were used to derive parametric site indices of removal priority and removal difficulty. Results indicate 59 top priority cases which should be the focus of immediate clean up efforts in the Florida Keys. Half of these cases are rated low to moderate in removal difficulty; the remainder are difficult to remove. Removal difficulty is a surrogate for removal cost: low difficulty -low cost, high difficulty - high cost. The rating scheme offers coastal planners options of focusing removal operations either on (1) specific areas with clusters of high priority derelict vessels or on (2) selected targeted derelicts at various, specific locations. (PDF has 59 pages.)

Some uses of the spontaneous polarization method

As a partial fulfillment of the requirements in obtaining a Professional Degree in Geophysical Engineering at the California Institute of Technology. Spontaneous Polarization method of electrical exploration was chosen as the subject of this thesis. It is also known as "self potential electrical prospecting" and "natural currents method."

The object of this thesis is to present a spontaneous polarization exploration work done by the writer, and to apply analytical interpretation methods to these field results.

The writer was confronted with the difficulty of finding the necessary information in a complete paper about this method. The available papers are all too short and repeat the usual information, giving the same examples. The decision was made to write a comprehensive paper first, including the writer's experience, and then to present the main object of the thesis.

The following paper comprises three major parts:

1 - A comprehensive treatment of the spontaneous polarization method.

2 - Report of the field work.

3 - Analytical interpretation of the field work results.

The main reason in choosing this subject is that this method is the most reliable, easiest and requires the least equipment in prospecting for sulphide orebodies on unexplored, rough terrains.

The intention of the writer in compiling the theoretical and analytical information has been mainly to prepare a reference paper about this method.

The writer wishes to express his appreciation to Dr. G. W. Potapenko, Associate Professor of Physics at California Institute of Technology, for his generous help.

Padal fishing - a unique fishing method in the Ashtamudi Estuary of Kerala (south India)

Bush park fishing / padal fishing is an indigenous fishing method widely employed in the Ashtamudi estuary of Kerala (south India). An artificial reef made from twigs and leaves of trees is planted in the shallow areas of the estuary. The aim is to harvest fish that find shelter in these structures for the purpose of feeding and breeding. Though the State Department of Fisheries has banned this method of fishing in the inland waters of Kerala, 400 padals are operating in this estuary. About 300 of them are anchored in the western parts of the estuary (west Kayal). Fish are harvested in the padals at monthly intervals almost round the year and this results in the destruction of a sizeable quantity of juveniles and sub-adults of the commercially important fishes, such as Pearl spot and mullets, from the estuary. These padals pose a major threat to the sustainability of the fishery resources of this estuary and, therefore, need to be phased out by providing alternative occupations for the fishermen who are dependant on the padals.

Selection and application of a suitable sampling method for quantitative and qualitative evaluation of lab-lab

Milkfish and prawn pond operation in the Philippines is often associated with lab-lab culture. Lab-lab is a biological complex of blue-green algae, diatoms, bacteria and various animals which form a mat at the bottom of nursery ponds or floating patches along the margins of ponds. This complex is considered the most favorable food of milkfish in brackishwater ponds. Variations in the quantity and quality of lab-lab between and within areas of a 1,000 sq. m. pond was determined over 2 culture periods (6 month duration) and the applicability and suitability of stratified random sampling as a method of sampling lab-lab was evaluated.

A body force-based method for prediction of multiple-pure-tone noise: Validation

Emissions, fuel burn, and noise are the main drivers for innovative aircraft design. Embedded propulsion systems, such as for example used in hybrid-wing body aircraft, can offer fuel burn and noise reduction benefits but the impact of inlet flow distortion on the generation and propagation of turbomachinery noise has yet to be assessed. A novel approach is used to quantify the effects of non-uniform flow on the creation and propagation of multiple pure tone (MPT) noise. The ultimate goal is to conduct a parametric study of S-duct inlets to quantify the effects of inlet design parameters on the acoustic signature. The key challenge is that the effects of distortion transfer, noise source generation and propagation through the non-uniform flow field are inherently coupled such that a simultaneous computation of the aerodynamics and acoustics is required to capture the mechanisms at play. The technical approach is based on a body force description of the fan blade row that is able to capture the distortion transfer and the blade-to-blade flow variations that cause the MPT noise while reducing computational cost. A single, 3-D full-wheel CFD simulation, in which the Euler equations are solved to second-order spatial and temporal accuracy, simultaneously computes the MPT noise generation and its propagation in distorted inlet flow. A new method of producing the blade-to-blade variations in the body force field for MPT noise generation has been developed and validated. The numerical dissipation inherent to the solver is quantified and used to correct for non-physical attenuation in the far-field noise spectra. Source generation, acoustic propagation and acoustic energy transfer between modes is examined in detail. The new method is validated on NASA's Source Diagnostic Test fan and inlet, showing good agreement with experimental data for aerodynamic performance, acoustic source generation, and far-field noise spectra. The next steps involve the assessment of MPT noise in serpentine inlet ducts and the development of a reduced order formulation suitable for incorporation into NASA's ANOPP framework. © 2010 by Jeff Defoe, Alex Narkaj & Zoltan Spakovszky.

Fabrication of photonic crystals on several kinds of semiconductor materials by using focused-ion beam method

In this paper, we introduced the fabrication of photonic crystals on several kinds of semiconductor materials by using focused-ion beam machine, it shows that the method of focused-ion beam can fabricate two-dimensional photonic crystal and photonic crystal device efficiently, and the quality of the fabricated photonic crystal is high. Using the focused-ion beam method, we fabricate photonic crystal wavelength division multiplexer, and its characteristics are analyzed. (c) 2007 Elsevier B.V. All rights reserved.

Nondestructive measurements of stoichiometry in undoped semi-insulating gallium arsenide by x-ray bond method

The influences of microdefects and dislocations on the lattice parameters of undoped semi-insulating GaAs single crystals were analyzed, and a novel nondestructive method for measuring stoichiometry in undoped semi-insulating GaAs was established in this letter. The comparison of this method with coulometric titration indicates that the method of nondestructive measurements is indeed convenient and reliable. (C) 1996 American Institute of Physics.

Application of the characteristic CIP method to a shallow water model on the sphere

Semi-implicit algorithms are popularly used to deal with the gravitational term in numerical models. In this paper, we adopt the method of characteristics to compute the solutions for gravity waves on a sphere directly using a semi-Lagrangian advection scheme instead of the semi-implicit method in a shallow water model, to avoid expensive matrix inversions. Adoption of the semi-Lagrangian scheme renders the numerical model always stable for any Courant number, and which saves CPU time. To illustrate the efficiency of the characteristic constrained interpolation profile (CIP) method, some numerical results are shown for idealized test cases on a sphere in the Yin-Yang grid system.

Method for calculating ecological water storage and ecological water requirement of marsh

As one of the most typical wetlands, marsh plays an important role in hydrological and economic aspects, especially in keeping biological diversity. In this study, the definition and connotation of the ecological water storage of marsh is discussed for the first time, and its distinction and relationship with ecological water requirement are also analyzed. Furthermore, the gist and method of calculating ecological water storage and ecological water requirement have been provided, and Momoge wetland has been given as an example of calculation of the two variables. Ecological water use of marsh can be ascertained according to ecological water storage and ecological water requirement. For reasonably spatial and temporal variation of water storage and rational water resources planning, the suitable quantity of water supply to marsh can be calculated according to the hydrological conditions, ecological demand and actual water resources.

Calculation of the bulk modulus of simple and complex crystals with the chemical bond method

The relation between the lattice energies and the bulk moduli on binary inorganic crystals was studied, and the concept of lattice energy density is introduced. We find that the lattice energy densities are in good linear relation with the bulk moduli in the same type of crystals, the slopes of fitting lines for various types of crystals are related to the valence and coordination number of cations of crystals, and the empirical expression of calculated slope is obtained. From crystal structure, the calculated results are in very good agreement with the experimental values. At the same time, by means of the dielectric theory of the chemical bond and the calculating method of the lattice energy of complex crystals, the estimative method of the bulk modulus of complex crystals was established reasonably, and the calculated results are in very good agreement with the experimental values.

A new preparation of zinc sulfide nanoparticles by solid-state method at low temperature

A novel solid-state method of the preparation of zinc sulfide nanoparticles is reported. By solid-state reaction of zinc acetate and thioacetamide at low temperature, zinc sulfide nanoparticles of different sizes were prepared. The temperature of preparation varied from room temperature to 300 degrees C. The particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), differential thermal analysis (DTA), and photoluminescence spectrum. X-ray diffraction patterns revealed that the particles exhibited pure zinc-blende crystal structure and that particle size increased with increasing temperature. The TEM micrograph showed that the mean particle size was about 40 nm for the sample heated at 100 degrees C. A blue shift was observed in the photoluminescence emission spectrum. A possible mechanism of the reaction corresponding to our observation is proposed, (C) 2000 Elsevier Science Ltd. All rights reserved.