Short course on principles and applications of beach nourishment

Covers the engineering aspects of beach nourishment. (Document is 192 pages

Cross likelihood ratio based speaker clustering using eigenvoice models

This paper proposes the use of eigenvoice modeling techniques with the Cross Likelihood Ratio (CLR) as a criterion for speaker clustering within a speaker diarization system. The CLR has previously been shown to be a robust decision criterion for speaker clustering using Gaussian Mixture Models. Recently, eigenvoice modeling techniques have become increasingly popular, due to its ability to adequately represent a speaker based on sparse training data, as well as an improved capture of differences in speaker characteristics. This paper hence proposes that it would be beneficial to capitalize on the advantages of eigenvoice modeling in a CLR framework. Results obtained on the 2002 Rich Transcription (RT-02) Evaluation dataset show an improved clustering performance, resulting in a 35.1% relative improvement in the overall Diarization Error Rate (DER) compared to the baseline system

How vertically specialized is Chinese trade?

Two recent phenomena have transformed the nature of world trade: the explosive growth of Chinese trade, and the growth of vertically specialized trade due to international production fragmentation. While vertical specialization may explain much of the growth and unique features of Chinese trade, few papers have quantitatively assessed these two phenomena together. In part, this is because it is difficult to measure just how vertically specialized Chinese trade is. The unique features of China's extensive processing trade cause both the identification of imported intermediate goods, and their allocation across sectors, to depend upon the Chinese trade regime. In this paper, we estimate the vertical specialization of Chinese exports, addressing these two challenges. Using two Chinese benchmark input-output tables, and a detailed Chinese trade dataset which distinguishes processing trade from other forms of trade, we develop a new method of identifying intermediate goods imported into China. Vertical specialization is then estimated using two methods. The first method uses the Hummels, Ishii and Yi (2001) measure, the official benchmark IO tables, and incorporates our identification correction. The second method follows the first, but also incorporates the Koopman, Wang and Wei (2008) method of splitting the benchmark IO tables into separate tables for processing and normal exports, in order to address the allocation problem. Results show strong evidence of an Asian network of intermediate suppliers to China, and the two methods provide a range of estimates for the foreign content of Chinese exports. In 2002 aggregate exports ranges between 25% and 46%, with some individual sectors are as high as 52%-95%. Across destinations, under both methods, the vertical specialization of Chinese exports declines with the level of development of the trading partner.China; fragmentation; vertical specialization; trade growth

Stability Analysis of Picard Iteration for Coupled Neutronics/Thermal-Hydraulics Simulations

In this paper, we present a formal Fourier analysis (FA) of Picard iteration for the coupled neutronics/thermal hydraulics (N/TH) problem and derive theoretical predictions for the spectral radius of Picard iteration for such coupled calculations as a function of the temperature difference between the fuel and coolant, temperature coefficients of cross sections (i.e., Doppler feedback), scattering ratio, and core height. An optimal underrelaxation factor is also derived based on the Fourier analysis

On the Smoothness of the Solution to the Two-Dimensional Radiation Transfer Equation

In this paper, we deal with the differential properties of the scalar flux defined over a two-dimensional bounded convex domain, as a solution to the integral radiation transfer equation. Estimates for the derivatives of the scalar flux near the boundary of the domain are given based on Vainikko's regularity theorem. A numerical example is presented to demonstrate the implication of the solution smoothness on the convergence behavior of the diamond difference method

Are foreign investors attracted to weak environmental regulations? Evaluating the evidence from China

One of the most contentious debates today is whether pollution-intensive industries from rich countries relocate to poor countries with weaker environmental standards, turning them into pollution havens. Empirical studies to date show little evidence to support the pollution haven hypothesis, but suffer potentially from omitted variable bias, specification, and measurement errors. The authors estimate the strength of pollution-haven behavior by examining the location choices of equity joint venture (EJV) projects in China. They derive a location choice model from a theoretical framework that incorporates the firm's production and abatement decision, agglomeration, and factor abundance. The authors estimate conditional logit and nested logit models using new data sets containing information on a sample of EJV projects, effective environmental levies on water pollution, and estimates of Chinese pollution-intensity for 3-digit ISIC (International Standard Industrial Classification) industries. Results from 2,886 manufacturing joint venture projects from 1993-96 show that EJVs from all source countries go into provinces with high concentrations of foreign investment, relatively abundant stocks of skilled workers, concentrations of potential local suppliers, special incentives, and less state ownership. Environmental stringency does affect location choice, but not as expected. Low environmental levies are a significant attraction only for joint ventures in highly-polluting industries with partners from Hong Kong, Macao, and Taiwan (China). In contrast, joint ventures with partners from OECD sources are not attracted by low environmental levies, regardless of the pollution intensity of the industry. The authors discuss the likely role of technological differences in explaining these results.Environmental Economics&Policies,Economic Theory&Research,Water and Industry,Decentralization,Public Health Promotion,Environmental Economics&Policies,Water and Industry,Economic Theory&Research,Health Monitoring&Evaluation,ICT Policy and Strategies

Springback analysis of AA5754 after hot stamping: experiments and FE modelling

In this paper, the springback of the aluminium alloy AA5754 under hot stamping conditions was characterised under stretch and pure bending conditions. It was found that elevated temperature stamping was beneficial for springback reduction, particularly when using hot dies. Using cold dies, the flange springback angle decreased by 9.7 % when the blank temperature was increased from 20 to 450 °C, compared to the 44.1 % springback reduction when hot dies were used. Various other forming conditions were also tested, the results of which were used to verify finite element (FE) simulations of the processes in order to consolidate the knowledge of springback. By analysing the tangential stress distributions along the formed part in the FE models, it was found that the springback angle is a linear function of the average through-thickness stress gradient, regardless of the forming conditions used

An Investigation, Using Standard Experimental Techniques, to Determine FLCs at Elevated Temperature for Aluminium Alloys

An experimental procedure has been developed for the determination of FLCs at elevated temperatures. The GOM ARGUS system was employed for measuring surface strain based on pre-applied grids (pattern), and limit strains were determined according to the ISO 12004-2:2008 standard. Forming limit curves (FLCs) have been determined for AA5754 under warm forming conditions in an isothermal environment. The tests were carried out at various temperatures up to 300oC and forming speeds ranging from 5 – 300 mm s-1 . Results reveal the significant effect of both temperature and forming speed on FLCs of AA5754. Formability increases with increasing temperature above 200oC. Formability also increases with decreasing speed. The presented FLC results show that the best formability exists at low forming speed and the high temperature end of the warm forming range

Mechanistic Study of Gold(I)-Catalyzed Intermolecular Hydroamination of Allenes

The intermolecular hydroamination of allenes occurs readily with hydrazide nucleophiles, in the presence of 3-12% Ph_3PAuNTf_2. Mechanistic studies have been conducted to establish the resting state of the gold catalyst, the kinetic order of the reaction, the effect of ligand electronics on the overall rate, and the reversibility of the last steps in the catalytic cycle. We have found the overall reaction to be first order in gold and allene and zero order in nucleophile. Our studies suggest that the rate-limiting transition state for the reaction does not involve the nucleophile and that the active catalyst is monomeric in gold(I). Computational studies support an “outersphere” mechanism and predict that a two-step, no intermediate mechanism may be operative. In accord with this mechanistic proposal, the reaction can be accelerated with the use of more electron-deficient phosphine ligands on the gold(I) catalyst