Adsorption Desalination Quenches Global Thirst

The search for fresh or potable water remains a pressing concern throughout many regions of the world. Although most of the Earth's surface is covered by oceans, the effort to provide for the world's inhabitants with fresh or potable water seems to be insurmountable; at least one billion people do not have access to clean and fresh water. The World Health Organization (WHO) reported that about 41% of the Earth's population lives in water-stressed areas, and the number of people in the water scarce regions may climb to 3.5 billion by the year 2025. Thus, innovative and cost-effective desalination technologies for producing fresh water are needed to provide practical solutions.     

A large discrepancy between CPM and ESR defect densities in light-soaked a-Si:H

A large discrepancy between defect densities evaluated by constant photocurrent method (CPM) and electron spin resonance (ESR) is investigated for hydrogenated amorphous silicon (a-Si:H) with various thicknesses in the process of light soaking (LS). It is shown by a computer simulation that the inhomogeneous defect distribution across the film thickness caused by a rather small penetration depth of the white light in the thick film is one of the possible origins of the discrepancy. But various other causes should also bring about the discrepancy, and the problem is still a puzzling one.     

Chain packing in graphs

This paper discusses the complexity of packingk-chains (simple paths of lengthk) into an undirected graph; the chains packed must be either vertex-disjoint or edge-disjoint. Linear-time algorithms are given for both problems when the graph is a tree, and for the edge-disjoint packing problem when the graph is general andk = 2. The vertex-disjoint packing problem for general graphs is shown to be NP-complete even when the graph has maximum degree three andk = 2. Similarly the edge-disjoint packing problem is NP-complete even when the graph has maximum degree four andk = 3.     

High-velocity impact experiment of aluminum foam sample using powder gun

Porous materials such as aluminum foam have been investigated for possible use as impact shock absorbers in transportation aeronautic applications. However, the response of aluminum foam during impacts at high velocities of more than 100 m/s is not yet fully understood. A high-velocity impact experiment was therefore carried out to clarify impact shock absorption properties of aluminum foam. A one-stage powder gun was used to accelerate an aluminum foam sample to impact a rigid wall. Velocity and deformation of the aluminum foam sample during impact was studied using a digital high-speed video camera, while the pressure wave in the aluminum foam sample was measured using a PVDF gauge. The experimental observations revealed uneven collapse of the aluminum foam sample structure during high speed impact with a general stress plateau effect, typical for cellular material structures when subjected to quasi-static loading.     

In Situ Observation of Deformation in Semi-solid Fe-C Alloys at High Shear Rate

Synchrotron X-ray radiography at 125 frames per second was used to study deformation mechanisms in semi-solid Fe-C alloys at high solid fraction and shear strain rates of 10^?1/s. An image correlation approach was also used to quantify the shear strain fields and study shear-induced dilation and the origin of shear cracking. It was shown that, at high solid fraction (90 to 93 pct solid), rearrangement including rotation and translation of solid particles became restricted and shear strain localized into narrow liquid-filled channels/fissures. Shear cracking was shown to originate from inadequate liquid flow into the expanding spaces between solid particles caused by shear-induced dilation. At lower solid fraction (~85 pct solid), solid particles rearranged with a significantly higher component of rotation leading to more shear-induced dilation and a wider shear band.     

Phase-diagram study for the Al2O3-CaF2-SiO2 system

Phase relations for the Al₂O₃-CaF₂-SiO₂ system were investigated from 1673 to 1723 K. The hotfilament technique was applied to observe a two-liquid region and liquidus for the ternary system. The liquidus saturated with SiO₂ was investigated at 1673 K by using the hot-filament technique and the chemical equilibrium technique. In this system, the addition of Al₂O₃ to the CaF₂-SiO₂ system reduces the congruent temperature. A small substitution of Al₂O₃ for CaF₂ increases the solubility of SiO₂, namely, if the region of liquid phase could be enlarged. These results suggest that Al₂O₃ would be an effective substitute of CaF₂ in slag for steelmaking.     

Numerical nonlinear observers using pseudo‐Newton‐type solvers

In constructing a globally convergent numerical nonlinear observer of Newton‐type for a continuous‐time nonlinear system, a globally convergent nonlinear equation solver with a guaranteed rate of convergence is necessary. In particular, the solver should be Jacobian free, because an analytic form of the state transition map of the nonlinear system is generally unavailable. In this paper, two Jacobian‐free nonlinear equation solvers of pseudo‐Newton type that fulfill these requirements are proposed. One of them is based on the finite difference approximation of the Jacobian with variable step size together with the line search. The other uses a similar idea, but the estimate of the Jacobian is mostly updated through a BFGS‐type law. Then, by using these solvers, globally stable numerical nonlinear observers are constructed. Numerical results are included to illustrate the effectiveness of the proposed methods. Copyright © 2007 John Wiley & Sons, Ltd.     

Eye-tracking device comparisons of three methods of magnetic resonance image series displays

This study evaluated the effectiveness of three kinds of display methods for magnetic resonance (MR) image interpretation using an eye-tracking device. Seven radiologists interpreted head MR studies by using a single monitor (17-inch, 1,024 X 1,280 bit) in the 4 images/screen display format. Three paging modes were compared: (A) rapid paging only, (B) multiple image series display at the same slice position with consecutive rapid paging, and (C) simultaneous display of multiple series with each image series being browsed independently. Using an eye-mark camera, the radiologist's point of fixation and the duration of fixation were recorded during actual image interpretation. In mode A, the duration of fixation was short, and the points of fixation were distributed randomly over the visual field. In mode B, the points of fixation were clustered chiefly on a specific image series. In mode C, the points of fixation were not clustered on a specified series, but the duration of viewing the T2 series was relatively long. The total tracing area in mode B and C was smaller than that in mode A. Multiple series display, in which selected key series of slices could be viewed effectively, was found to be suitable for MR image interpretation.