Biases of Success Rate Differences Shown in Binomial Effect Size Displays.

The intent of a binomial effect size display (BESD) is to show "the [real-world] importance of [an] effect indexed by a correlation [r]" (R. Rosenthal, 1994, p. 242) by reexpressing this correlation as a success rate difference (SRD) (e.g., treatment group success rate - control group success rate). However, SRDs displayed in BESDs generally overestimate real-world SRDs implied by correlations of (a) dichotomous X and Y variables (φ coefficients), (b) dichotomous X and continuous Y variables (point-biserial coefficients [rphs]). and (c) continuous X and Y variables (rxys). Furthermore, overestimation biases are larger for rxys than for rphs. Differences in the sizes of biases linked to different correlations suggest that BESD SRDs reported for different correlations are not comparable. The stochastic difference index (N. Cliff, 1993: A. Vargha & H. D. Delaney, 2000) is recommended as an alternative to the BESD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The LHC pre-series dipole cold mass geometry

In order to provide the necessary mechanical aperture for the LHC beam, the main dipole cold masses have to match precisely the nominal circular trajectory of the particles beam. The requirements on the dipole cold mass geometry are dictated by the LHC beam optics and by the allowed limits of mechanical deformation of the interconnection bellows. Keeping the tight tolerances that are imposed necessitates a well controlled bending process and the use of a high accuracy 3D measuring instrument for checking the geometry of the cold mass throughout many manufacturing stages up to the final inspection. The dipole cold mass pre-series production started in 2000. It is almost completed at the three sites. In this paper, we report on the problems encountered to shape correctly the cold masses, their effect on interconnection of the dipole cold masses and on the mechanical aperture. On one side measures to improve the production process in terms of accuracy and reproducibility were taken, on the other side the assembly tolerances could be relaxed following a thorough review of the machine requirements. The summary of the encountered problems, corrective actions and results obtained on the pre-series cold masses are presented and discussed.     

Structured low-density parity-check codes

This article describes the different methods to design regular low density parity-check (LDPC) codes with large girth. In graph terms, this corresponds to designing bipartite undirected regular graphs with large girth. Large girth speeds the convergence of iterative decoding and improves the performance at least in the high SNR range, by slowing down the onsetting of the error floor. We reviewed several existing constructions from exhaustive search to highly structured designs based on Euclidean and projective finite geometries and combinatorial designs. We describe GB and TS LDPC codes and compared the BER performance with large girth to the BER performance of random codes. These studies confirm that in the high SNR regime these codes with high girth exhibit better BER performance. The regularity of the codes provides additional advantages that we did not explore in this article like the simplicity of their hardware implementation and fast encoding.     

Alternating-direction implicit (ADI) formulation of the finite-difference time-domain (FDTD) method: algorithm and material dispersion implementation

The alternating-direction implicit finite-difference time-domain (ADI-FDTD) technique is an unconditionally stable time-domain numerical scheme, allowing the /spl Delta/t time step to be increased beyond the Courant-Friedrichs-Lewy limit. Execution time of a simulation is inversely proportional to /spl Delta/t, and as such, increasing /spl Delta/t results in a decrease of execution time. The ADI-FDTD technique greatly increases the utility of the FDTD technique for electromagnetic compatibility problems. Once the basics of the ADI-FDTD technique are presented and the differences of the relative accuracy of ADI-FDTD and standard FDTD are discussed, the problems that benefit greatly from ADI-FDTD are described. A discussion is given on the true time savings of applying the ADI-FDTD technique. The feasibility of using higher order spatial and temporal techniques with ADI-FDTD is presented. The incorporation of frequency dependent material properties (material dispersion) into ADI-FDTD is also presented. The material dispersion scheme is implemented into a one-dimensional and three-dimensional problem space. The scheme is shown to be both accurate and unconditionally stable.     

Scale Up from Small Oven-Drying Tests of Mineral Concentrate to Pilot-Scale Drying with a Heated Pad

While Fickian diffusion models are commonly used in other applications, there are few reports of them being applied to the batch drying of a mineral concentrate. Diffusion coefficients estimated from small-scale oven-drying tests were used to predict the drying behavior of a concentrate sample 1 m × 1 m in area and 50 cm deep, with a heated bottom pad. These pilot-scale tests included both daily turning of the sample and turning every three days. The excellent quantitative agreement between the predicted and observed pilot-scale behavior gives a high level of confidence in the model predictions and suggests that a Fickian diffusion model is adequate to predict the behavior of mineral concentrates at the low moisture contents used here.     

Feasibility analysis of phonon lasers

We identify the main reason impeding coherent generation of phonons in solid state - the inherently high density of phonon states. Based on the results of our analysis we formulate a set of conditions that may make phonon lasing practical and point out the most promising mechanism of phonon lasing: LO/spl rarr/LA+TO in InP. We then develop a complete set of phonon laser equations and evaluate the threshold, output power and efficiency of phonon lasers based on InP MESFET. We show that one can obtain high-power 1.26-THz coherent phonon emission with pump power as small as a few milliwatts and up to 5% slope efficiency. Potential applications are also discussed.     

A suitable computational strategy for the parametric analysis of problems with multiple contact

The aim of the present work is to develop an application of the LArge Time INcrement (LATIN) approach for the parametric analysis of static problems with multiple contacts. The methodology adopted was originally introduced to solve viscoplastic and large‐transformation problems. Here, the applications concern elastic, quasi‐static structural assemblies with local non‐linearities such as unilateral contact with friction. Our approach is based on a decomposition of the assembly into substructures and interfaces. The interfaces play the vital role of enabling the local non‐linearities, such as contact and friction, to be modelled easily and accurately. The problem on each substructure is solved by the finite element method and an iterative scheme based on the LATIN method is used for the global resolution. More specifically, the objective is to calculate a large number of design configurations. Each design configuration corresponds to a set of values of all the variable parameters (friction coefficients, prestress) which are introduced into the mechanical analysis. A full computation is needed for each set of parameters. Here we propose, as an alternative to carrying out these full computations, to use the capability of the LATIN method to re‐use the solution to a given problem (for one set of parameters) in order to solve similar problems (for the other sets of parameters). Copyright © 2003 John Wiley & Sons, Ltd.     

Grain size effects in the charpy impact energy of a thermally embrittled RPV steel

The Charpy impact energies of a reactor pressure vessel (RPV) steel in the as-received and several thermally embrittled conditions have been assessed on the basis of microstructural parameters. It has been concluded that the parameters controlling the impact-absorbed energy of pre-cracked and side-grooved Charpy test specimens are the equivalent grain size of dual-phase annealed microstructures, and the bainite packet size of single-phase quenched and tempered materials. The Charpy energy has been correlated very well with the reduction in area and true fracture strain of tensile specimens, which could be inferred as grain size governed mechanical properties.     

Managing R&D alliances within government: the "virtual agency" concept

The virtual agency concept is now used within the United States Government as an alliance approach to manage large research and development (R&D) processes across departments. This paper examines the history of the virtual agency concept and its important characteristics. The paper identifies the potential benefits and associated risks involved in managing R&D within a virtual agency. Three cases are examined where the virtual agency concept has been applied to R&D programs: the High Performance Computing and Communications initiative, the Next Generation Internet, and the Partnership for a New Generation of Vehicles. The case studies indicate that the R&D process is attempting to balance formal process controls with the agility to adapt rapidly to new research opportunities. Virtual agencies can be used to improve organizational efficiency, improve knowledge transfer, increase interoperability through standards, provide better alignment of agency missions with national policy, and introduce increased flexibility into the R&D process. At the same time, the virtual agency concept has major risks including inefficiencies due to organizational complexity, the danger of collective myopia, the problem of adopting standards too early, the difficulty of reaching objectives in a loose organizational structure, and the problem of properly balancing the tension between agency mission objectives and national policy agendas.