Qualitative aspects of the Bradford distribution

A study was performed to determine whether the quality of journal articles declines as one moves through successively less productive Bradford zones. Two measures of qualityrate of citation and expert judgement-were used. It was found that articles in the least productive zone were cited significantly less than those in the most productive zone. However, experts did not judge them to be of lesser quality.     

A VLSI CMOS delay oriented waveform converter for polyphasefrequency synthesizer

In this paper, we present a waveform converter implemented on a 0.25-μm CMOS technology using a dedicated design methodology (Delay Oriented Design). The circuit converts a square wave signal in both in-phase and quadrature-phase sinusoidal differential outputs. It also multiplies the frequency by seven. The output frequency range of this converter extends from 1.05 GHz up to 2.17 GHz. This converter is dedicated for the design of a third-generation mobile phone synthesizer using a double-loop architecture. For an output frequency of 2 GHz, the measured phase noise at 10-kHz offset from the carrier is -97 dBc/Hz. The circuit consumes 50 mW from a 2.5-V supply     

IBM's Linux watch, the challenge of miniaturization

Nearly four years in development, the IBM Linux watch contains a complete computer system that runs Linux, displays X11 graphics, and has wireless connectivity. The system fits in a case that could pass as a slightly unusual analog timepiece with a somewhat odd shape and an extraordinarily brilliant face. The developers have created two versions of the watch, one with an organic light-emitting diode display and the other with a liquid crystal display. Still considered a research prototype, the watch already runs some personal information management applications, and it can communicate with PCs, PDAs, and other wireless-enabled devices, viewing condensed e-mail and directly receiving pager-like messages. Eventually, users will be able to access various Internet-based services, such as up-to-the-minute information about weather, traffic conditions, the stock market, and sports     

The use of Schottky barrier diodes for the detection of surface contamination and damage in the fabrication of GaAs MESFETS

The gates of GaAs MESFETS rely on the formation of a Schottky diode between the semiconductor surface and a deposited metal and so are extremely sensitive to the nature of this interface. For this reason an investigation of surface damage and contamination by the various processing stages involved in IC fabrication has been undertaken. This paper outlines the results obtained from processes involved in activation of ion implantation through annealing with a dielectric encapsulant, wet chemical etching, and metallization. Methods for removing or minimizing the effects of processing damage or contamination are also investigated.     

p,V, T and derived thermodynamic data for toluene,trichloromethane, dichloromethane,acetonitrile, aniline,and n-dodecane

Experimentally determined p,V,T data are reported for toluene, trichloromethane, dichloromethane, acetonitrile, aniline, and n-dodecane at 278, 288, 298, 313, and 323 K, except for dichloromethane, for which the highest temperature was 298 K. At each temperature, measurements were done at pressures up to about 280 MPa or (for aniline and n-dodecane) at a lower pressure slightly below the freezing pressure at the temperature of measurement. Values of the isobaric expansivity isothermal compressibility and (for toluene, trichloromethane, dichloromethane, and acetonitrile) internal pressure, derived from the p,V,T data, are presented.     

Adaptive smoothing: a general tool for early vision

A method to smooth a signal while preserving discontinuities is presented. This is achieved by repeatedly convolving the signal with a very small averaging mask weighted by a measure of the signal continuity at each point. Edge detection can be performed after a few iterations, and features extracted from the smoothed signal are correctly localized (hence, no tracking is needed). This last property allows the derivation of a scale-space representation of a signal using the adaptive smoothing parameter k as the scale dimension. The relation of this process to anisotropic diffusion is shown. A scheme to preserve higher-order discontinuities and results on range images is proposed. Different implementations of adaptive smoothing are presented, first on a serial machine, for which a multigrid algorithm is proposed to speed up the smoothing effect, then on a single instruction multiple data (SIMD) parallel machine such as the Connection Machine. Various applications of adaptive smoothing such as edge detection, range image feature extraction, corner detection, and stereo matching are discussed     

Ultimate strength analysis of structural components using the continuum damage mechanics approach

In this study, an analytical model is developed to include the effect of material fracture on the overall behavior of a structure. The continuum damage mechanics approach is used to describe the continuous deterioration of the material stiffness that leads to total failure. The damage evolution is assumed to be anisotropic and the effect of the triaxiality of stress on the fracture criterion is included in the analysis. The above modifications were applied to an existing finite element program which is capable of including both geometric and material nonlinearities in the analysis. The program was used to analyze a welded tubular connection (T-joint). This joint was chosen because fracture was shown experimentally to control its ultimate behavior. Solid finite elements were used to model the chord and the branch in the intersection region, wedge elements were used for the weld profile, and the rest of the geometry was modeled using shell elements. The joint was subjected to an increasing amount of displacement at the far end of the branch. The loading was continued until total failure. During this process, the evolution of the damage and its propagation were monitored. Divergence of the solution was obtained at a failure load of 42.4 kips compared to 44.0 kips obtained experimentally. In addition, the failure mode of the joint predicted by the analysis was identical to that observed experimentally.