10,504 research outputs found

    Efficient estimation of a semiparametric partially linear varying coefficient model

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    In this paper we propose a general series method to estimate a semiparametric partially linear varying coefficient model. We establish the consistency and \sqrtn-normality property of the estimator of the finite-dimensional parameters of the model. We further show that, when the error is conditionally homoskedastic, this estimator is semiparametrically efficient in the sense that the inverse of the asymptotic variance of the estimator of the finite-dimensional parameter reaches the semiparametric efficiency bound of this model. A small-scale simulation is reported to examine the finite sample performance of the proposed estimator, and an empirical application is presented to illustrate the usefulness of the proposed method in practice. We also discuss how to obtain an efficient estimation result when the error is conditional heteroskedastic.Comment: Published at http://dx.doi.org/10.1214/009053604000000931 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    The Peierls-Nabarro model as a limit of a Frenkel-Kontorova model

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    We study a generalization of the fully overdamped Frenkel-Kontorova model in dimension n≥1.n\geq 1. This model describes the evolution of the position of each atom in a crystal, and is mathematically given by an infinite system of coupled first order ODEs. We prove that for a suitable rescaling of this model, the solution converges to the solution of a Peierls-Nabarro model, which is a coupled system of two PDEs (typically an elliptic PDE in a domain with an evolution PDE on the boundary of the domain). This passage from the discrete model to a continuous model is done in the framework of viscosity solutions

    Simulation of hydrogen production for mobile fuel cell applications via autothermal reforming of methane

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    This paper presents a simulation of catalytic autothermal reforming (ATR) of methane (CH4) for hydrogen (H2) production. ATR is essentially an oxidative steam reforming, which combines the exothermic partial oxidation (PO) with the endothermic steam reforming (SR) under thermally neutral conditions. A model is developed using HYSYS 2004.1 to simulate the conversion behavior of the reformer. The model covers all aspects of major chemical kinetics and heat and mass transfer phenomena in the reformer. The ATR and preferential oxidation (PrOx) processes is modeled using conversion reactor, while the water gas shift (WGS) process is modeled using equilibrium reactor within HYSYS environment. The conditions used for high CH4 conversion and high H2 yield are at air to fuel ratio of 2.5 and water to fuel ratio of 1.5. Under this condition, CH4 conversion of 100% and H2 yield of 44% on wet basis can be achieved and the system efficiency is about 87.7%

    Derivation and study of dynamical models of dislocation densities

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    In this paper, starting from the microscopic dynamics of isolated dislocations, we explain how to derive formally mean field models for the dynamics of dislocation densities. Essentially these models are tranport equations, coupled with the equations of elasticity. Rigorous results of existence of solutions are presented for some of these models and the main ideas of the proofs are given

    Muzik kontemporari sebagai alat pembentukan nilai dalam komuniti: Ke mana halatuju kita?

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    Kertas kerja ini akan membincangkan ruanglitup nilai-nilai murni yang seharusnya diamlkan dalam sesebuah komuniti. Nilai-nilai ini akan dikaitkan pula dengan pola proses penyemaian dan pengukuhannya melalui pelbagai saluran, salah satu daripadanya ialah muzik. Perkembangan muzik Melayu daripada segi penciptaan, penyusunan, penggubahan, penciptaan lirik serta pematahan lagu akan digalurkan secara ringkas daripada muzik asli, muzik tahun-tahun 50-an, 60-an, 70-an, 80-an sehinggalah muzik kontemporari. Seterusnya, kertas kerja ini akan memperlihatkan bagaimana proses globalisasi telah mempengaruhi dunia muzik Melayu di Malaysia dan telah membentuk sebuah wajah muzik kontemporari yang bertumangkan nilai-nilai muzik global dan tidak berpaksi kepada nilai-nilai budaya Melayu. Tumpuan akan diberikan kepada pola penciptaan lagu serta corak pematahan lagu (penyebutan lirik lagu) oleh penyanyi-penyanyi kontemporari yang begitu berpengaruh di kalangan generasi muda. Beberapa persoalan akan ditimbulkan. Bagaimanakah rupa bentuk lagu-lagu Melayu yang harus digalakkan sebagai alat pembentuk nilai-nilai jati diri Melayu? Apakah langkah-langkah yang harus dilakukan oleh semua pihak (terutamanya Kementerian Pelajaran dan Kementerian Kesenian, Kebudayaan dan Warisan) untuk memperkukuhkan penyemaian nilai-nilai murni bangsa Malaysia melalui seni muzik, sejajar dengan perkembangan dunia pascamodenisme

    CMLHS luncheon at Bukit Gambang Resort

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    19 January 2012. The Welfare Unit of CMLHS (UNIK) was really creative. Instead of having the event at night, this year, all CMLHS members were treated with a luncheon at Bukit Gambang Resort. Clad in batik and sitting in a very relaxed mood made everyone enjoyed themselves. UNIK was generous too when everyone was presented goodie bag with a lovely mug and Gambang Theme Park voucher inside

    Research Workshop for Research Grant

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    4 April 2012. A workshop to enhance the proposal for university’s grant was conducted at the Banquet Hall, Chancellery, for CMLHS lecturers. The workshop was spearheaded by none other than Associate Professor Dr Muhammad Nubli Abdul Wahab, CMLHS Deputy Dean (Research & Development)
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