Automated tracking of liquid velocities in a refractive index matched porous medium

Abstract

Particle tracking velocimetry is applied to flow inside a porous column at Reynolds number Re = 28. The column is composed of refractive‐index‐matched solid and liquid materials, allowing seeding particles to be tracked in a laser‐illuminated axial slice. To complement earlier results acquired for 7 mm spheres, we conduct new experiments with larger 12 mm spheres. By improving the image acquisition and analysis, we are able to process the new experiments using fully automated algorithms instead of manual tracking. As a result, greater vector yields, more accurate velocity data, and a more complete spatial coverage are achieved.     

A comparison of sitting posture adaptations of pregnant and non-pregnant females

The postural differences between seated pregnant and non-pregnant subjects were studied, and the effects of various sitting workstation designs were assessed. Five pregnant and five non-pregnant subjects participated in this study. The experimental variables were the table-chair-vertical-distance (35 cm and 30 cm) and the seat-inclination-angle (0°, +10° and +20°). The seated working postures of the last 10 min of a 50-min sitting session were videotaped and analyzed using a 2D motion analysis system. Postural differences were observed between the pregnant and non-pregnant groups which may be attributed to the changes and/or mechanisms associated with pregnancy. The increased size of the abdomen requires more room in front of the body; in the pregnant subjects this was obtained by holding the upper-arm further from the body, inclining the upper trunk more anterior, and extending the hip more. A seat with a sloping angle of 10° was found to reduce the biomechanical loading on the lower back and in subjective ratings from both groups, was preferred over the other seat angles.

Relevance to industry

Pregnant women make up a small but significant part of the workforce. Changes in body form and working posture due to pregnancy change the effective working envelope and increase the biomechanical loads on the musculoskeletal system resulting in an increase in the risk of lower-back pain. This study examined the posture adaptations and the effects of workstation design on pregnant and non-pregnant subjects.     

Effects of inelastic scattering on interband tunneling inGaSb/AlSb/InAs/GaSb/AlSb/lnAs broken-gap interband tunneling structures

Effects of inelastic scattering on interband tunneling in GaSb/AlSb/InAs/GaSb/AlSb/InAs BGIT's are investigated. The broadening mechanisms due to inelastic scattering are incorporated into the interband tunneling theory. The transmission and reflection coefficients are calculated with the aid of a three-band model, in which the conduction, light-hole, and split-off bands are coupled with one another. It is found that the inelastic scattering lowers the transmission peak and broadens the full-width at half-maximum, resulting in the decrease of the tunneling current. The calculated tunneling current due to inelastic scattering is found to have better agreement with the experiments. In addition, as the valley current plays an important role in the peak-to-valley current ratio (PVR), we then try to deduce the origin of the valley currents. The thermionic current is included in the valley current to estimate the peak-to-valley current ratio. The thermionic component from the GaSb well has important contribution to the valley current in the studied structures. The peak-to-valley current ratio is also estimated and found to have better agreement with the experiment when the inelastic scattering is considered     

Resistive switching behavior in Lu2O3 thin film for advanced flexible memory applications

In this article, the resistive switching (RS) behaviors in Lu₂O₃ thin film for advanced flexible nonvolatile memory applications are investigated. Amorphous Lu₂O₃ thin films with a thickness of 20 nm were deposited at room temperature by radio-frequency magnetron sputtering on flexible polyethylene terephthalate substrate. The structural and morphological changes of the Lu₂O₃ thin film were characterized by x-ray diffraction, atomic force microscopy, and x-ray photoelectron spectroscopy analyses. The Ru/Lu₂O₃/ITO flexible memory device shows promising RS behavior with low-voltage operation and small distribution of switching parameters. The dominant switching current conduction mechanism in the Lu₂O₃ thin film was determined as bulk-controlled space-charge-limited-current with activation energy of traps of 0.33 eV. The oxygen vacancies assisted filament conduction model was described for RS behavior in Lu₂O₃ thin film. The memory reliability characteristics of switching endurance, data retention, good flexibility, and mechanical endurance show promising applications in future advanced memory.     

A survey of the use schools make of IT linked to museum visits

Abstract  The purpose of this survey was to evaluate the quality of work produced by pupils and students using information technology (IT) in various forms in either museums themselves or in schools in association with a visit to a museum. During the survey HM Inspectors visited nine museums and galleries and saw a wide range of groups from mainly primary and some secondary schools. Classes in a further four primary schools, one middle school and one secondary school were inspected. Information technology is now a well-established resource in almost every school and college in the United Kingdom and an increasing number of museums and galleries have introduced it to give visitors a greater understanding of some of their exhibits.     

Synthesis of Polyurethane Foam Considering Mixture Blowing Agents for Application to Cryogenic Environments

Polyurethane foams, which are among the most widely used insulating materials, are generally fabricated by the chemical reaction between isocyanate and polyol‐containing chemical additives and blowing agents. Recently, many kinds of blowing agents have been used for the fabrication process of polyurethane foam, such as hydrochlorofluorocarbons (HCFCs) and chlorofluorocarbons (CFCs). However, issues have continuously arisen regarding the destruction of the ozone layer due to these compounds. In the present study, polyurethane foams are manufactured using a mixture of water blowing agents and hydrofluorocarbons (HFC‐365mfc). These samples are subjected to mechanical tests to investigate the effects of the blowing agents on the mechanical properties of the polyurethane foam within a temperature range of 25 to ?163 °C. In addition, thermal and microstructural investigations are conducted depending on the content of the HFC‐365mfc. From the scanning electron microscopy observations, the sizes of the structure cells and the windows are found to decrease with the increase in HFC‐365mfc content. In addition, from the Fourier transform‐infrared spectroscopy observations, the chemical bonds that affect mechanical performance are found to be more distributed with the increase in HFC‐365mfc content.     

Comportement electrochimique et reactivite du systeme Ag(II)/Ag(I)-bipyridine dans le carbonate de propylene—IV. Etude du mecanisme de l'oxydation catalytique de la methyl-4 pyridine et de la dimethyl-2,6 pyridine

The reactivity of the Ag(II)/Ag(I)-bipyridine system towards substituted pyridines L (L = 4-Mepy, 2,6-diMepy) has been investigated during electrolysis of the Ag^I(bipy)⁺ complex in various medium conditions. This study, using voltammetry, coulometry and EPR points out the influence of the substrate geometry upon the catalytic oxidation mechanism. The processes, involving mixed complexes of silver(II) Ag^II(bipy)L²⁺_n (n = 1,2), are relevant of a chemical catalysis of electrochemical oxidations.     

Haptic Direct-Drive Robot Control Scheme in Virtual Reality

This paper explores the use of a 2-D (Direct-Drive Arm) manipulator for mechanism design applications based on virtual reality (VR). This article reviews the system include a user interface, a simulator, and a robot control scheme. The user interface is a combination of a virtual clay environment and human arm dynamics via robot effector handler. The model of the VR system is built based on a haptic interface device behavior that enables the operator to feel the actual force feedback from the virtual environment just as s/he would from the real environment. A primary stabilizing controller is used to develop a haptic interface device where realistic simulations of the dynamic interaction forces between a human operator and the simulated virtual object/mechanism are required. The stability and performance of the system are studied and analyzed based on the Nyquist stability criterion. Experiments on cutting virtual clay are used to validate the theoretical developments. It was shown that the experimental and theoretical results are in good agreement and that the designed controller is robust to constrained/unconstrained environment.     

Gas-Assisted IR-ATR Probe for Detection of Volatile Compounds in Aqueous Solutions

The application of the principle of solid-phase microextraction (SPME) to attenuated total reflectance (ATR) infrared (IR) probes can provide a convenient and sensitive way to detect volatile organic compounds (VOCs) in aqueous solutions. In this paper a new method to increase the performance of this type of sensing device is proposed. A stream of gas purges out VOCs from aqueous solution. These compounds are directed to an internal-reflection sensor. Several advantages are recognized by this new method as compared with a conventional liquid probe; these include a longer lifetime for the probe, higher selectivity in the detection of VOCs, less limitation in the sample volume, and easier regeneration of the sensing probe.