Analysis of a diffusive effective mass model for nanowires

We propose in this paper to derive and analyze a self-consistent model describing the diffusive transport in a nanowire. From a physical point of view, it describes the electron transport in an ultra-scaled confined structure, taking in account the interactions of charged particles with phonons. The transport direction is assumed to be large compared to the wire section and is described by a drift-diffusion equation including effective quantities computed from a Bloch problem in the crystal lattice. The electrostatic potential solves a Poisson equation where the particle density couples on each energy band a two dimensional confinement density with the monodimensional transport density given by the Boltzmann statistics. On the one hand, we study the derivation of this Nanowire Drift-Diffusion Poisson model from a kinetic level description. On the other hand, we present an existence result for this model in a bounded domain

Development of Artificial Neural Network Software And Models For Engineering Materials

Artificial Neural Network (ANN), which is inspired by biological neural networks in the human brain, is one important tool of machine learning that creates artificial intelligence through computational systems. The creation of this intelligence is contingent on learning from available data regarding a specific subject. Although machine learning, in general, has profuse applications in most scientific disciplines, yet few have been developed in civil engineering due to the required time consuming and demanding programming. In order to minimize this, intelligible ANN software has been developed in this research capable of training networks with any number of hidden layers and nodes for each layer. Furthermore, two models have been created to demonstrate the robust applications of ANN. The first application involves a simulation of the straintemperature behavior of a shape memory alloy (SMA) under thermal cycling. In the second case, the bond strength between the concrete and the steel-reinforced bars is predicted considering the effects of steel corrosion level, concrete compressive strength, and concrete cover. Java programming language was used in developing the ANN software and a simple graphical user interface (GUI) has been designed, allowing the user to control the inputs and the training progress, make predictions and save the outputs. In this study, the ANN models were developed with different structures and activation functions to prove the ANN eminent idiosyncrasy of modeling data from different fields. Comparison is made between these models as well as models created by statistical iv regression and other models available in the literature. The developed software can efficiently train ANNs with any structure, as less time is needed to develop one ANN using the software than using programming methods. Moreover, the user will have the option to save the weights and the biases at any iteration and predict responses for the currently trained or previously trained ANN. The model predicted results can be saved or exported as an excel file. In terms of the created models, ANN can capture highly complicated relationships accurately and effectively compared to traditional modeling methods. Based on that, more accurate predictions are expected using ANN

Non Parametric Distributed Inference in Sensor Networks Using Box Particles Messages

This paper deals with the problem of inference in distributed systems where the probability model is stored in a distributed fashion. Graphical models provide powerful tools for modeling this kind of problems. Inspired by the box particle filter which combines interval analysis with particle filtering to solve temporal inference problems, this paper introduces a belief propagation-like message-passing algorithm that uses bounded error methods to solve the inference problem defined on an arbitrary graphical model. We show the theoretic derivation of the novel algorithm and we test its performance on the problem of calibration in wireless sensor networks. That is the positioning of a number of randomly deployed sensors, according to some reference defined by a set of anchor nodes for which the positions are known a priori. The new algorithm, while achieving a better or similar performance, offers impressive reduction of the information circulating in the network and the needed computation times

Single and Pair Production of Doubly Charged Higgs Bosons at Hadron Colliders

Current searches for doubly charged Higgs bosons (H^{\pm\pm}) at the Fermilab Tevatron are sensitive to single production of H^{\pm\pm}, although the pair production mechanism q\bar q\to H^{++}H^{--} is assumed to be dominant. In the context of a Higgs Triplet Model we study the mechanism q'\bar q\to H^{\pm\pm}H^{\mp} at the Tevatron and CERN Large Hadron Collider, and show that its inclusion can significantly improve the search potential for H^{\pm\pm}. Moreover, assuming that the neutrino mass is generated solely by the triplet field Yukawa coupling to leptons, we compare the branching ratios of H^{\pm\pm}\to l^\pm l^\pm and H^{\pm\pm}\to H^\pm W^* for the cases of a normal hierarchical, inverted hierarchical and degenerate neutrino mass spectrum.Comment: 17 pages, 15 figures, references added, version to appear in PR

Gated metabolic myocardial imaging, a surrogate for dual perfusion-metabolism imaging by positron emission tomography

Acknowledgments The authors are grateful for the help from Dr H Ali and Dr A Dawson. Funding: This study was performed using a research grant from the Aberdeen Royal Hospitals Trust's Endowment Fund, with further support from the Department of Medical Physics at the University of Aberdeen, for which the authors express their gratitude.Peer reviewedPublisher PD

Phase-Convex Arcs in Root Space and Their Application to Robust SPR Problem

This paper considers the problem of identifying regions in the complex-plane, such that polynomials having roots in those regions, have their phase bounded by that of a few extreme polynomials. We present sufficient and testable conditions for different regions satisfying this property. Applications of the results to the robust SPR analysis and synthesis problems are illustrated

An unusual presentation of acute lymphoblastic leukaemia with peri-cardial effusion causing cardiac tamponade

Peri-cardial effusion is most commonly associated with tuberculous infection in the developing world. Peri-cardial effusion causes symptoms when it is large or when it has accumulated rapidly. Non-tuberculous causes of peri-cardial effusion include bacterial infections, uraemia, viral infections, rheumatic fever, connective tissue disorders, post – peri-cardiotomy syndromes and malignancy. We present a case of acute lymphoblastic leukaemia first presenting as a large peri-cardial effusion causing tamponade

Second language acquisition of Arabic: the development of negation and interrogation among learners in the U.K.

The study is an investigation of Interlanguage (IL) developmental sequences of the acquisition of some aspects of negation and interrogation in Arabic by English-speaking learners in a foreign- language context; (i.e.Britain).The thesis contains eight chapters. The first chapter discusses the purpose of this research and the reason for selecting the topic.Chapters two and three survey and discuss the relevant literature. This includes discussions of different approaches to Second Language Acquisition (SLA), of models and hypotheses which have been proposed concerning the nature of learners' language and the process of SLA; and of studies of variability in language, both in general and specifically in the field of SLA.In chapter four, we analyze the two structures which are to be investigated in the study. First, basic assumptions of Arabic are discussed. Then, a short, analysis of the form of each structure is presented in both languages (Arabic and English). In the course of the analysis other issues that, are essential for the understanding of the realization of the features in the two languages are discussed.Chapter five presents first the hypotheses concerning the constraints which may govern the learners' IL(s). The rest of the chapter provides details of the investigation. The subjects are described, the tasks outlined, and details of data collection are described. Finally the criteria used in assessing the learners' responses are discussed.In chapter six, the results of the analysis are presented. Chapter seven contains the discussion and interpretation of the results in relation to the hypotheses formulated. The final chapter, chapter eight, summarizes the findings of the study in regard to the hypotheses. It also discusses some of the broader implications of the results of the study. Some suggestions for further investigations are also made

Giant spin-dependent photo-conductivity in GaAsN dilute nitride semiconductor

A theoretical and experimental study of the spin-dependent photoconductivity in dilute Nitride GaAsN is presented. The non linear transport model we develop here is based on the rate equations for electrons, holes, deep paramagnetic and non paramagnetic centers both under CW and pulsed optical excitation. Emphasis is given to the effect of the competition between paramagnetic centers and non paramagnetic centers which allows us to reproduce the measured characteristics of the spin-dependent recombination power dependence. Particular attention is paid to the role of an external magnetic field in Voigt geometry. The photoconductivity exhibits a Hanle-type curve whereas the spin polarization of electrons shows two superimposed Lorentzian curves with different widths, respectively related to the recombination of free and trapped electrons. The model is capable of reproducing qualitatively and quantitatively the most important features of photoluminescence and photocurrent experiments and is helpful in providing insight on the various mechanisms involved in the electron spin polarization and filtering in GaAsN semiconductors.Comment: 10 pages, 5 figure

On Robustness Analysis in the Control of Nonlinear Systems

This paper deals with the class of nonlinear systems described by the equation M(q(t))q(t) = f(t) - N(q(t),q¿(t)) with f(t) a control input. We employ a simple method of control design which has two stages. First, a global linearization is performed to yield a decoupled controllable linear system. Then a controller is designed for this linear system. We provide a rigorous analysis of the effects of uncertain dynamics, which we study using robustness results in the time domain based on a Lyapunov equation and the total stability theorem. Using this approach we are able to give meaningful robustness bounds which justify assumptions that are currently made in the literature in an ad hoc fashion