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Scientific Computing with MATLAB and Octave
No full textThis textbook is an introduction to Scientific Computing, in which several numerical methods for the computer solution of certain classes of mathematical problems are illustrated. The authors show how to compute the zeros or the integrals of continuous functions, solve linear systems, approximate functions by polynomials and construct accurate approximations for the solution of ordinary and partial differential equations. To make the presentation concrete and appealing, the programming environments Matlab and Octave, which is freely distributed, are adopted as faithful companions. The book contains the solutions to several problems posed in exercises and examples, often originating from specific applications. A specific section is devoted to subjects which were not addressed in the book and contains the bibliographical references for a more comprehensive treatment of the material. The second edition features many new problems and examples, as well as more numerical methods for linear and nonlinear systems and ordinary and partial differential equations. This book is presently being translated or has appeared in the following languages: Italian, German, French, Chinese and Spanish. Reviews for "Scientific Computing with MATLAB" - 1st edition: " ... Scientific Computing with MATLAB is written in a clear and concise style, figures, tables and formula boxes complement the explanations... The whole book is an invitation, if not a request, of the authors to the reader to play with MATLAB, apply its powerful menagerie of functions to solve the given (or own) problems - in brief, supervised learning by doing .... is a stimulating introductory textbook about numerical methods that successfully combines mathematical theory with programming experience..." Anselm A.C. Horn, Journal of Molecular Modeling 2004 "... An excellent addition to academic libraries and university bookstores, this book will be useful for self-study and as a complement to other MATLAB-based books. Highly recommended. Upper-division undergraduates through professionals." S.T. Karris, Choice 2003.CMCSWritten for: Undergraduate and graduate students in computational science, mathematics and sciences
Band offsets at the Ge/GeO2 interface through hybrid density functionals
No full textBand offsets of the Ge/GeO2 interface are calculated through a hybrid density functional scheme. We first generate a model of disordered GeO2 through ab initio molecular dynamics to describe the oxide component. For addressing the interface, we then consider an atomistic model in which amorphous GeO2 is connected to crystalline Ge through a suboxide transition region showing regular structural parameters. The band offsets are obtained through the application of an alignment scheme, which reproduces the experimental band gaps of the interface components. The calculated valence band offset of 3.7 eV favors the low-energy side of the range of measured offsets.CSE
PEMERINTAH SELINGKUHI BUMDES: Inkonsistensi Kebijakan Negara, Kinerja BUMDes, dan Jalan Panjang Keberlanjutan Ekonomi Desa
No full textPembangunan desa tidak pernah sekadar soal dana, program, atau lembaga. Ia adalah soal “arah kebijakan, keteguhan institusi, dan keberanian negara untuk konsisten pada pilihannya sendiri”. Dalam satu dekade terakhir, Indonesia telah menunjukkan komitmen besar terhadap desa melalui Undang-Undang Desa, penguatan fiskal desa, serta kelahiran Badan Usaha Milik Desa (BUMDes) sebagai instrumen ekonomi lokal. Namun, di tengah euforia kebijakan tersebut, muncul pertanyaan mendasar, “apakah kita benar-benar sedang membangun fondasi ekonomi desa yang berkelanjutan, atau sekadar mengganti program demi program tanpa konsistensi institusional?
Automatic Time Skew Detection and Correction
No full textIn this paper, we propose a new approach for the automatic time skew detection and correction for multisource audiovisual data, recorded by different cameras/recorders during the same event. All recorded data are successfully tested for potential time skew problem and corrected based on ASR-related features. The core of the algorithm is based on perceptual time-quefrency analysis with a precision of 10 ms. The results show correct time skew detection and elimination in 100% of cases for a real life dataset of 32 broken sessions and surpass the performance of fast cross correlation while keeping lower system requirements.LIDIA
1.3-μm Mode-Locked Disk Laser With Wafer Fused Gain and SESAM Structures
No full textWe report 1.3-mu m mode-locked optically pumped semiconductor disk laser (SDL) made by wafer fusion. The gain medium and the saturable absorber, both based on an InP material system, were integrated with AlGaAs-GaAs distributed Bragg reflectors by localized wafer fusion. An intracavity wedged diamond heat spreader capillary bonded to the gain chip prevents the disruption of 6.4-ps pulse spectrum and supports 100 mW of average power. The results reveal an advantage of wafer fusion process of disparate materials over monolithically grown InP-based gain/absorber structures and demonstrate practical potential of the technique for long-wavelength SDLs.LP
Unravelling the Behavior of Dion-Jacobson Layered Hybrid Perovskites in Humid Environments
No full textLayered hybrid halide perovskites are known to be more environmentally stable than their 3D analogues. The enhanced stability is particularly relevant for Dion-Jacobson-type layered perovskites due to their promising photovoltaic performances. However, in contrast to the expected resilience to moisture, we reveal that the structure of Dion-Jacobson perovskite phases based on a 1,4-phenylenedimethanammonium spacer is disrupted in humid conditions using X-ray diffraction, UV-vis spectroscopy, thermogravimetric analysis, and solid-state NMR spectroscopy. The process takes place at >= 65 +/- 5% relative humidity, with a time scale on the order of minutes. The original layered structure can be restored upon annealing and the hydration can be suppressed by postsynthetic annealing in air, which is attributed to the generation of a self-protective layer of PbI2. This study thereby reveals a unique behavior of layered perovskites in humid environments, which is critical to their stabilizing role in perovskite devices.LRMLP
Thick-film Load-sensing bridges – Effect of Temperature and Mechanical Boundary Conditions
No full textAlthough inorganic thick-film materials are usually very stable, load sensors (i.e. force, torque and pressure) based on the piezoresistive effect of thick-film resistors often exhibit some drift, with major contributions stemming from a) temperature changes or gradients, coupled with the temperature coefficient of resistance (TCR) of the sensing bridge resistors, and b) ill- defined mechanical boundary conditions, due to insufficient decoupling, plastic deformation used materials, friction or loading errors. These problems also potentially affect test samples for measuring piezoresistive response, a.k.a. the gauge factors. Here, we examine and discuss effects on the output signal of simple cantilever force sensors of two disturbances: parasitic loads and temperature gradients, and discuss / demonstrate mitigation options, and a system to reliably measure gauge factor.LP
Topics at the Interface of Ergodic Theory, Number Theory, and Combinatorics
No full textErgodic theory is concerned with the study of the dynamical behavior of measure-preserving systems and has far-reaching applications across several areas of mathematics. The purpose of this thesis is to investigate various facets of the interaction of ergodic theory with number theory and combinatorics, addressing several problems that fall within this framework. We focus on two distinct directions: combinatorial applications of ergodic theory, and multiplicative structures in dynamics.
The first topic addressed in this thesis concerns finding structured patterns in dense subsets of abelian groups. The application of ergodic theory to combinatorial problems of this nature was initiated in 1977 by Furstenbergâ s ergodic proof of Szemerédiâ s theorem. Furstenbergâ s approach has been extensively developed ever since. Building on this, Kra, Moreira, Richter and Robertson recently established a conjecture of ErdË os about infinite sumsets in dense subsets of the positive integers. In the first part of this thesis we extend their result, along with related work by Kousek and RadiÄ , from the natural numbers to abelian groups and, in some cases, to amenable groups. Our approach builds on the ergodic methods developed by Kra, Moreira, Richter, and Robertson, which we extend non-trivially to the more general setting of amenable groups.
The second topic of this thesis focuses on the connections between ergodic theory and multiplicative number theory. A striking example showcasing this connection is the well-known Sarnakâ s conjecture asserting that the Möbius (or the Liouville) function should be orthogonal to all deterministic sequences. Moreover, dynamics underlie problems in multiplicative number theory that may not initially appear dynamical at all. A prominent example is the famous conjecture of Chowla, predicting the asymptotic independence of the Liouville function at consecutive integers. Building on this perspective, Bergelson and Richter reformulated and extended several classical theorems and conjectures from number theory in the dynamical setting. Moreover, recent work by Klurman, Moreira, and Frantzikinakis has shown that the study of multiplicative measure-preserving systems has applications to problems concerning partition and density regularity of homogeneous quadratic equations. Inspired by these recent
developments, the second part of this thesis is concerned with the study of multiplicative structures in dynamics. By transferring several number-theoretic concepts into the ergodic setting, we explore convergence and recurrence phenomena in multiplicative measure-preserving systems. In addition, we establish several results in multiplicative number theory, featuring theorems on the asymptotic behavior of completely multiplicative functions along linear patterns, extending a result of Klurman-Mangerel, as well as the joint distribution of Ω(n) in two consecutive integers along logarithmic averages, obtaining a natural generalization of Taoâ s theorem on the logarithmically averaged two-point Chowlaâ s conjecture.ER
Design and R&D of an ECRH system on JET
No full textAn electron cyclotron resonance heating (ECRH) system has been designed for JET in the framework of the JET enhanced-performance project (JET-EP) under the European Fusion Development Agreement (EFDA). Due to financial constraints it has recently been decided not to implement this project. Nevertheless, the design work conducted from April 2000 to January 2002 shows a number of features that can be relevant in preparation of future ECRH systems, e.g. for ITER. (C) 2003 Elsevier B.V. All rights reserved.CRPPSP