A fast multispeed comma-free Reed-Solomon decoder for W-CDMA applications using foldable systolic array architecture

This brief proposes a fast multispeed comma-free Reed-Solomon (CFRS) decoder for the frame synchronization and code-group identification in the cell search of the Third Generation Partnership Project wide-band code-division multiple access/frequency division duplexing (W-CDMA/FDD) system. A foldable systolic array is proposed to achieve fast decoding and provide flexible tradeoffs between power consumption, chip size, and decoding latency. Multispeed decoding, an idea that is useful for cell search in different application scenarios, can also be achieved with the same array architecture. The proposed CFRS decoder is implemented in a 3.3-V 0.35-/spl mu/m CMOS technology with 2.2 /spl times/ 2.2 mm/sup 2/ core area and power dissipation of 13.3 and 1.23 mW in high- and low-speed decoding modes, respectively.     

MLSE equalization and decoding for multipath-fading channels

The performance of a receiver using a combined MLSE (maximum likelihood sequence estimation) equalizer/decoder and D-diversity reception is analyzed for multipath Rayleigh fading channels. An upper bound on the (decoded) bit error probability is derived. Comparisons to simulation results show that this upper bound is quite tight when the system has a high signal-to-noise ratio or when diversity reception is used. The upper bound involves an infinite series that must be truncated at a point where the remainder can be safely assumed to be small. An algorithm based on a one-directional stack algorithm is proposed for this calculation because it makes efficient use of computer memory     

Evaporation model of a single hydrocarbon fuel droplet due to ambient turbulence at intermediate Reynolds numbers

A general evaporation model of a single liquid fuel droplet under various ambient turbulence conditions at intermediate droplet Reynolds numbers is proposed combining the current and previous experimental results. Extensive evaporation experiments of single fuel droplets are conducted at room temperature in quasi-laminar and turbulent environments at Reynolds numbers in the range of 72-333. Tested hydrocarbon fuels include by pentane, hexane, heptane, octane and decane. Flow fields, behind a perforated plate or a circular disk in a vertical low-speed wind tunnel, provide the required ambient turbulent environments for droplet evaporation experiments. The ambient turbulence intensities vary in the range of 1-60% and the integral length scales in the range of 0.5-20 times of the initial droplet diameter. Results show that normalized evaporation rate (K/K_L) decreases with increasing effective Damköhler number (0.0001<Da_v<0.1) and is approximately equal to unity with further increasing Damköhler number (0.1<Da_v<1).     

The gridded trihedral: a new polarimetric SAR calibration reflector

The characteristics of the gridded trihedral used to calibrate polarimetric synthetic-aperture radar (SAR) systems are considered. The gridded trihedral is a normal trihedral with one of the conducting faces replaced with a grid of closely spaced (relative to a wavelength) parallel conductors over a layer of microwave absorber. This grid changes the incident wave's polarization and results in a calibration target with a significant cross-polarized reflection. The advantages of the gridded trihedral are that it has a broad backscatter beamwidth (unlike the dihedral), and that it is passive and simple to construct (unlike the active radar calibrator, or ARC). The performance characteristics of the gridded trihedral reflector are reviewed, using basic theoretical models and calibrated P-3 SAR imagery     

Fiber-alignment shifts in butterfly laser packaging by laser-welding technique: Measurement and finite-element method analysis

The post-weld shift (PWS)-induced fiber-alignment shifts of fiber-ferrule clip (FFC) joints in butterfly laser packaging by using laser-welding techniques and a high-magnification, video-probe camera system were studied experimentally and numerically. The measured results show that the fiber shifts of FFC joints with a 5-μm gap between the clip and ferrule exhibited shifts less than that without a gap. This suggests that the 5-μm gap design may be more suitable for FFC joints in laser packaging. The experimental measurements of fiber shifts in FFC joints were in reasonable agreement with the numerical calculations of the finite-element method (FEM) analysis. The major fiber-shift formation mechanisms of FFC joints in the laser-welding process may come from the mismatch of the thermal expansion coefficient, the solidification shrinkage, and the residual stresses within the FFC joint, but solidification shrinkage is the dominant cause. This study demonstrates that the FEM is an effective method for predicting PWS-induced fiber-alignment shifts in laser-module packaging.     

Amount and type of dietary lipid modulate rat hepatic cytochrome P-450 activity

Cardiovascular responses to sustained and rhythmic (5 s on, 2 s off) forearm isometric exercise to fatigue at 40% maximal voluntary contraction (MVC) and to a period of arterial occlusion were investigated in elite rock climbers (CLIMB) as a trained population compared to non-climbing sedentary subjects (SED). Blood pressure (BP), monitored continuously by Finapres, and forearm blood flow, by venous occlusion plethysmography, were measured and used to calculate vascular conductance. During sustained exercise, times to fatigue were not different between CLIMB and SED. However, peak increases in systolic (S) BP were significantly lower in CLIMB [25 (13) mmHg; (3.3 (1.7) kPa] than in SED [48 (17) mmHg; (6.4 (2.3) kPa] (P < 0.05), with a similar trend for increases in diastolic (D) BP. Immediately after sustained exercise, forearm conductance was higher in CLIMB than SED (P < 0.05) for up to 2 min. During rhythmic exercise, times to fatigue were two fold longer in CLIMB than SED [853 (76) vs 420 (69) s, P < 0.05]. Increases in SBP were not different between groups except during the last quarter of exercise when they fell in CLIMB. Conductance both during and after rhythmic exercise was higher in CLIMB than in SED. Following a 10-min arterial occlusion, peak vascular conductance was significantly greater in CLIMB than SED [0.597 (0.084) vs 0.431 (0.035) ml x min(-1) x 100 ml(-1) x mmHg(-1); P < 0.05]. The attenuated BP response to sustained isometric exercise could be due in part to enhanced forearm vasodilatory capacity, which also supports greater endurance during rhythmic exercise by permitting greater functional hyperaemia in between contraction phases. Such adaptations would all facilitate the ability of rock climbers to perform their task of making repetitive sustained contractions.     

A Capacity Analysis Method for Uplinks in DS/CDMA Cellular Systems with Imperfect SIR-Based Power Control and Multipath Fading

The letter proposes a method to analyze the system capacity of uplinks with imperfect SIR-based power control in direct sequence/code division multiple access (DS/CDMA) cellular systems with the multipath fading. It considers the received signal-to-interference ratio (SIR) as a random variable due to imperfect SIR-based power control. Based on assumptions regarding the average received SIR, a set of linear equations for the average received power on each uplink is derived. An outage-based system capacity can be then obtained according to the feasibility of the average received power vector and the average bit error rate. Finally, by applying central limit theorem, a closed-form solution for system capacity is approximately derived. Results show that numerical results of the closed-form solution have a good match with simulation results, which supports the validity of the proposed capacity analysis method.