Non-equilibrium and non-linear stationary state in thermoelectric materials

Efficiency of thermoelectric materials is characterized by the figure of merit Z. Z has been believed to be a peculiar material constant. However, the accurate measurements in the present work reveal that Z has large size dependence and a non-linear temperature distribution appears as stationary state in the thermoelectric material. The observation of these phenomena is achieved by the Harman method. This method is the most appropriate way to investigate the thermoelectric properties because the dc and ac resistances are measured by the same electrode configuration. We describe the anomalous thermoelectric properties observed in mainly (Bi,Sb)2Te3 by the Harman method and then insist that Z is not the peculiar material constant but must be defined as the physical quantity dependent of the size and the position in the material.Comment: 9 pages, 4 figures. submitted to Applied Physics Lette

2-D Physical Modeling to Measure the Effectiveness of Perforated Skirt Breakwater for Short-Period Waves

The effectiveness of a breakwater can be measured by quantifying the transmission coefficient (KT). The smaller the coefficient, the better the performance of the breakwater. A physical modeling on the proposed breakwater was conducted to identify the coefficient of Perforated Skirt Breakwater (PSB). The PSB model was tested in 2-D wave flume at Ocean Wave Research Laboratory FTSL ITB, to obtain the effectiveness of PSB for short-period waves (prototype periods, Tp= 4 second and smaller). The scaling of PSB models applies the principle of Froude Similarity, where the Froude number in model equals to the Froude number in prototype (Frm=Frp). The flume is equipped with 5 resistance-type wave probes and 8-channel DAS (Data Acquisition System). Wave heights (H) and wave periods (T) data were observed both manually by visual observation and wave probes readings (processed later with method of “zero mean up-crossing” technique). The incoming wave heights (Hi) and transmitted wave heights (Ht) were measured and processed to obtain the transmission coefficient (KT). The relationships between KT and non-dimensional variables (skirt draft / incident wave height, S/Hi) are analyzed and the calculated effectiveness of the PSB for varied environmental condition is obtained to be up to 70%

The Dual Feminisation of HIV/AIDS

This is an Accepted Manuscript of an article published by Taylor & Francis in Globalizations on 2011, available online: http://wwww.tandfonline.com/10.1080/14747731.2010.49302

3-d Physical Modelling On Floating - Type Breakwater

BP Tangguh has port facilities in Bintuni Bay, West Papua, with a water depth of about 6 to 9 m. To secure the port activities and facilities, a floating-type breakwater was proposed. Three-dimensional physical modeling was conducted in a wave basin to determine its effectiveness against environmental conditions in Bintuni Bay by quantifying the transmission coefficient (KT). The basin was equipped with pistons to generate a monochromatic wave, four wave probes, and an eight-channel DAS (Data Acquisition System). Wave height (H) and period (T) data were recorded by the wave probes and validated by peilschaal observation. The incoming (Hi) and transmitted wave heights (Ht) before and after the breakwater, respectively, were measured and processed to obtain KT. The relationships between KT and non-dimensional variables were analyzed. The proposed floating-type breakwater was found to be effective for intermediate and short waves but not for long waves. Meanwhile, configuration 1 was choosen since the smaller structure still resulted in similar transmission waves compared to configuration 2. For the short waves, the floating-type breakwater resulted in transmission coefficients ranging from 0.5 to 0.7. The value of KT declined when the wave period became smaller

Nuclear-size self-energy and vacuum-polarization corrections to the bound-electron g factor

The finite nuclear-size effect on the leading bound-electron g factor and the one-loop QED corrections to the bound-electron g factor is investigated for the ground state of hydrogen-like ions. The calculation is performed to all orders in the nuclear binding strength parameter Z\alpha\ (where Z is the nuclear charge and \alpha\ is the fine structure constant) and for the Fermi model of the nuclear charge distribution. In the result, theoretical predictions for the isotope shift of the 1s bound-electron g factor are obtained, which can be used for the determination of the difference of nuclear charge radii from experimental values of the bound-electron g factors for different isotopes

Modeling Pressurized Water Reactor Kinetics

A computer model of a pressurized water reactor (PWR) was developed for use as a teaching tool in graduate level nuclear reactor courses. The development, based on the diffusion equation, includes the methodology for solving the steady state spatial dependence of the neutron power output in a homogeneous right circular cylinder unreflected PWR system. This includes a two dimensional one energy group model, a three dimensional one energy group model, and a three dimensional two energy group model. To solve the homogeneous diffusion equation, a method was developed to search for criticality of the reactor based on the geometry and reactor core material composition. For the one energy group models, a perturbation technique was developed to assist the program user in modifying the macroscopic absorption coefficient to drive the reactor to criticality. For the three dimensional models, a blocked tridiagonal solver was developed to solve the numerical linear system of equations approximating the diffusion equation. The model was coded using Visual BASIC 5.0™. This provides a platform that is exportable to personal computers and allows direct linkage to Windows based programs. The code automatically charts and displays the power distribution profile using Excel™ and displays the calculated multiplication factor determining criticality

QED theory of the nuclear magnetic shielding in hydrogen-like ions

The shielding of the nuclear magnetic moment by the bound electron in hydrogen-like ions is calculated ab initio with inclusion of relativistic, nuclear, and quantum electrodynamics (QED) effects. The QED correction is evaluated to all orders in the nuclear binding strength parameter and, independently, to the first order in the expansion in this parameter. The results obtained lay the basis for the high-precision determination of nuclear magnetic dipole moments from measurements of the g-factor of hydrogen-like ions.Comment: 4 pages, 2 tables, 2 figure

X-ray frequency combs from optically controlled resonance fluorescence

An x-ray pulse-shaping scheme is put forward for imprinting an optical frequency comb onto the radiation emitted on a driven x-ray transition, thus producing an x-ray frequency comb. A four-level system is used to describe the level structure of N ions driven by narrow-bandwidth x rays, an optical auxiliary laser, and an optical frequency comb. By including many-particle enhancement of the emitted resonance fluorescence, a spectrum is predicted consisting of equally spaced narrow lines which are centered on an x-ray transition energy and separated by the same tooth spacing as the driving optical frequency comb. Given a known x-ray reference frequency, our comb could be employed to determine an unknown x-ray frequency. While relying on the quality of the light fields used to drive the ensemble of ions, the model has validity at energies from the 100 eV to the keV range.Comment: 11 pages, 2 figure