Three-dimensional atom probe study of the segregation behaviour of Ni91Pt9 alloy after sputtering

To investigate local ordering and segregation phenomenon in a Ni91Pt9-alloy after sputtering and annealing a 3D optical atom probe (OAP) has been used. The specimen tips have been prepared from polycrystalline samples. To sputter the samples a separate preparation chamber with a scannable Ar-sputter-gun is connected to the OAP vessel. When necessary, the sample can be electrically heated to induce segregation and cure the altered layer. After a heat treatment of a Ni91 at. %Pt 9 at.% specimen at 1100 K the surface of a (111)-oriented specimen is enriched in platinum by a factor of two in relation to the bulk. The phenomenon of short-range ordering has been investigated on the surface and in the subsurface volume. A 3D reconstruction of this annealed NiPt specimen shows regions with high concentration of platinum that gives an indication at short-range ordering. Uniform sputtering of the tip without a heat treatment induces a decisive depletion of Pt on the surface and the following subatomic layers. The atom-probe results of specimens in thermal equilibrium are in close agreement to further surface sensitive results obtained from Ion Scattering Spectroscopy (ISS) and Auger Electron Spectroscopy (AES).     

Correlation of the leakage current and charge pumping in silicon oninsulator gate-controlled diodes

The leakage and charge pumping currents were measured in gate-controlled MOS p-i-n diodes fabricated on thin SIMOX substrates. The efficiencies of the techniques as well as their complementary features are analyzed for various experimental conditions. The interface properties of device-grade SIMOX wafers are characterized and shown to be compatible with VLSI requirements. Special interface coupling effects, which occur only in fully depleted SOI devices and modify the conventional signature of charge pumping and leakage current, are thoroughly investigated     

R&D activities on wireless systems in China

Various wireless systems and the research preceding their practical use in China are described. The topics discussed include research establishments, research and development projects underway, challenges inherent to digital radio, and expansion opportunities afforded by satellite communications     

Optical fiber solitons, their properties and uses

The history and mathematical formulation of solutions are briefly reviewed. Solitons of the nonlinear Schrodinger equation are studied in greater detail because they describe nonlinear pulse propagation on dispersive optical fibers. The proposal by A. Hasegawa and the experiments of L.F. Mollenauer on long distance soliton propagation for use in repeaterless transoceanic fiber transmission cables are described. In 1986, limitations on the distance that can be spanned by a repeaterless link for a given bit rate were shown to exist. It has been shown recently that by proper design these limitations can be overcome, so that newer transoceanic cable designs are likely to utilize solitons. The special properties of solitons make them particularly suited for all optical switching and logic operations. Some recent experiments with such switches are described     

Component-relevancy and characterization results in multistatesystems

Two new versions of component relevancy for multistate structure functions are introduced. They are compared with some existing component-relevance conditions and their general properties are investigated. Based on the two relevance conditions, two component-importance measures for multistate systems are defined; they are most appropriate for comparing components when a certain type of system improvement is considered. Series and parallel structures are characterized within the L-superadditive and L-subadditive structure functions by imposing the two new relevance conditions     

Improved spacer design and cost reduction in an electrodialysis system

In electrodialysis using thin membranes and spacers, the compactness of the membrane cell-pairs leads to a small potential drop, and hence to energy saving. The spacer design itself has a great effect on the cost of the plants, since spacers act as turbulence promoters. A careful design, to increase the mass transfer coefficients, can reduce the membrane surface area required for a given application. Limiting current measurements, cell-pair resistance and pressure losses are presented for several thin spacers, for different flow-velocity values and feed water concentrations. It was possible to find an advantageous geometry of the separating mesh leading to substantial savings on investment and operation costs.     

Studies of the compositions of Pd(II) hydrolysis products

The characterization of the clusters formed on alkaline hydrolysis of [PdCl₄]^2– was performed using¹⁷O,²³Na,³⁵Cl,¹³³Cs NMR and UV spectroscopy. The chemical composition of the clusters was found to be [Pd(OH)₂] _n ·nNaCl. No mononuclear oxo- or hydroxocomplexes were detected. The spatial structure of the clusters is stabilized by alkali metal cations.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 675–679, April, 1993.     

Solving ML equations for 2-parameter Poisson-process models forungrouped software-failure data

Existence conditions are given for maximum likelihood (ML) parameter estimates for several families of 2-parameter software-reliability Poisson-process models. For each such model, the ML equations can be expressed in terms of one equation in one unknown. Bounds are given on solutions to these one equation problems to serve as initial intervals for search algorithms like bisection. Uniqueness of the solutions is established in some cases. Solutions are also tabulated for certain simple cases. Results are given for ungrouped failure data (exact times are available for all failures). ML estimation problems for such a situation are treated as limiting cases of problems based on failure times grouped into intervals of decreasing mesh