Spectroscopic, thermal and mechanical behavior of allylthiourea cadmium chloride single crystals

Allylthiourea cadmium chloride, a promising non-linear optical material was grown from aqueous solution by slow evaporation technique. Single crystal X-ray diffraction studies reveal that the crystal is trigonal structure with R3C space group. The spectroscopic properties were investigated by recording the Fourier transform infrared and optical absorption spectra. The dielectric studies of the sample were carried out at varying temperatures in the frequency range from 50 Hz to 5 MHz. The thermal properties were studied using thermogravimetric analyses and photopyroelectric technique. It is evident from the thermal studies that the decomposition of the crystal begins around 200 °C. The microhardness test conducted on the grown crystal suggests that the crystal has a relatively high mechanical strength. The second harmonic generation efficiency of the crystal was studied and found to be nearly 1.5 times that of urea.     

Formation of composition-modulated alloys by electrodeposition

A method has been developed to produce composition-modulated alloys by electrodeposition. The method was demonstrated for the copper-nickel couple. Salts of the two component metals are dissolved in a common electrolyte and the potential is alternately pulsed for fixed durations between values above and below the reduction potential of the less noble component. Co-deposition of the nobler metal into the other metal layer is diminished by setting unfavourable diffusion conditions during the more cathodic pulse. Modulation was achieved down to 0.8 nm thick layers. The resulting composition-modulated alloys were analysed by Auger spectroscopy and X-ray diffraction.     

One-pixel-wide edge detection

This paper describes a new edge detection technique for obtaining spatially accurate single-pixel-wide edges in a gray scale image. The edge detection first detects multi-pixel-wide edges. Then, it reduces the edge width by a thinning edge operation. A heuristic search (i.e. minimum cost search) is then used to obtain optimal one-pixel-wide edges. Finally the detected one-pixel-wide edges are encoded for efficient edge data manipulation, storage, and retrieval. Experimental images are illustrated for showing the effectiveness of the edge detection.     

Improvement of the non-destructive evaluation of plasma facing components by data combination of infrared thermal images

To increase the reliability of non-destructive examinations of plasma facing components (PFC), we present steps in order to make data combination in this study. The industrial issue is the inspection of manufacturing quality of these components which must support a very high-heat flux in Tokamaks. The experimental study was conducted on trial components for the Wendelstein 7X stellarator using two benches of infrared thermal imaging equipment. The first bench measures the surface temperature with an internal excitation of the components. The second bench uses a lock-in thermal imaging method. The data fusion method makes use of the Dempster–Shaffer theory of evidence. We show that we can improve the decision making for the quality diagnostic. This study could be generalized to other combinations of non-destructive tests for current Tokamaks or those under development like the future ITER reactor.     

Throughput of unslotted direct-sequence spread-spectrummultiple-access channels with block FEC coding

An analysis of unslotted random-access direct-sequence spread-spectrum multiple-access (DS/SSMA) channels with block forward error correction (FEC) coding is presented. Extending a methodology that was introduced in an earlier paper on unslotted packet code-division multiple access (CDMA) without coding, a procedure for calculating the error probability of an L-bit packet in the variable message length, FEC-coded, DS/SSMA environment is described. This procedure is then used in conjunction with appropriate flow equilibrium traffic models to compute channel throughput. Using BCH block coding as an example, the analytical model is exercised to obtain throughput versus channel traffic curves over a range of code rates, leading to an assessment of maximum achievable throughput and the associated optimum FEC code rate. The results show that the use of block FEC coding provides a significant improvement in the bandwidth-normalized channel throughput (utilization), approaching values competitive with those for comparable narrowband ALOHA channels     

Bombardment Induced Electron-Capture Processes at Sodium Halide Surfaces

Discrete features observed in the energy distribution of electrons emitted from ion-bombarded sodium halide surfaces can be attributed to a new type of collisional deexcitation mechanism. Such a mechanism involves sodium atoms in bombardment-excited autoionizing states that are the result of cascade collisions within the crystal lattice. This deexcitation process, in contrast to that for a metal, is not simply a consequence of the inner-shell lifetime of the initial collisionally excited sodium Na⁺* ion. Rather, the deexcitation consists of a sequence of lattice collisions during which the excited Na⁺* ion captures an electron to form the inner-shell-excited Na⁰* states responsible for the observed transitions. The formation of such autoionizing Na⁰* states is described within the framework of a new model in which excitation processes and localized collisional electron-transfer mechanisms are taken into account. These localized electron-transfer processes make possible new channels for electronic deexcitation, chemical dissociation, and defect production; they are critical for understanding inelastic ion-surface collisions in solids.     

The Different Catalytic Routes for Methane Valorization: An Assessment of Processes for Liquid Fuels

Scope of Review. This review is written from the point of view of the process design engineer trying to find the best catalytic options for upgrading methane. It is not intended to be a review of catalytic principles. In fact, actual catalysts used are only mentioned in passing. If the reader wishes to explore this aspect further, there are many recent review articles that can be used and these are referred to at an appropriate time and place.     

Multiple sexual partners and their psychosocial correlates: The population-based AIDS in Multiethnic Neighborhoods (AMEN) Study.

In this study we examined multiple partners in a household probability sample of heterosexuals. Thirty-seven percent reported 2 or more partners in the past year, and 6% reported 5 or more partners. Significant interactions among gender, ethnicity, and relationship status revealed complex relations. African American men without a primary partner were the most likely to have multiple partners; ethnic minority women with primary partners were the least likely. Psychosocial factors associated with multiple partners were examined with the AIDS Risk Reduction Model (ARRM). Situational factors influenced how ARRM variables related to multiple partners. Perceived risk, commitment to monogamy, and communication were all important correlates. Prevention efforts must focus on increasing awareness of the risks of heterosexual transmission of HIV for people in dating relationships and on strengthening sexual communication skills with new partners. (PsycINFO Database Record (c) 2010 APA, all rights reserved)