An approach for high-yield requirements capture for e-commerce and its application

Web-based e-commerce software is typically real-time, responsive, and distributed software that must meet high quality requirements. Moreover, because of its Internet-based operating environment, e-commerce software must deal with concurrency, synchronization, and non-deterministic issues (such as delays) primarily caused by the heavy usage load and underlying network conditions. In this paper, we introduce a generic, cost-effective approach to optimize requirements capture (and subsequent development and testing) with respect to functional coverage and customer perception of quality. This high-yield approach is presented and illustrated by application to an e-commerce online shopping system and used to explain the principles of use-case requirements captured in the unified modeling language. Published online: 25 July 2001     

Effect of dead space on gain and noise ofdouble-carrier-multiplication avalanche photodiodes

The effect of dead space on the statistics of the gain in a double-carrier-multiplication avalanche photodiode (APD) is determined using a recurrence method. The dead space is the minimum distance that a newly generated carrier must travel in order to acquire sufficient energy to become capable of causing an impact ionization. Recurrence equations are derived for the first moment, the second moment, and the probability distribution function of two random variables that are related, in a deterministic way, to the random gain of the APD. These equations are solved numerically to produce the mean gain and the excess noise factor. The presence of dead space reduces both the mean gain and the excess noise factor of the device. This may have a beneficial effect on the performance of the detector when used in optical receivers with photon noise and circuit noise     

Dissolution Rates of Commercial Phenylbutazone Tablets: Inter-And Intra-Brand Effects

A study has been carried out to investigate the dissolution rate profiles of twelve batches of sugar-coated phenylbutazone tablets belonging to four commercial brands. Using the rotating basket method, significant inter-brand and inter-batch variations in dissolution rates were found. Only two batches of one brand passed the B.P. dissolution limit whilst other batches had percentages dissolution between 0.3 and 58 after 45 min. Batches with poor dissolution characteristics exhibited significant tablet-to-tablet variations in dissolution rates; a finding which was not observed in the relatively fast-dissolving batches. When the paddle method was substituted for the B.P. basket method, the dissolution rates were relatively faster but similar dissolution failure was found. However, the tablet-to-tablet dissolution variability was decreased in some of the batches. The observed differences in dissolution rates of the batches examined were unrelated to their disintegration times. Inspite of the poor dissolution characteristics of most of the batches studied, no apparent chemical degradation was found. It is recommended that when evaluating the dissolution rates of brands of phenylbutazone tablets, a number of batches from each brand should be tested.     

Isolated agenesis of the mastoid antrum

The first isolated case of agenesis of the mastoid antrum, previously only described in association with the congenital syndromes trisomy 13 and mandibulofacial dysostosis, is reported. The loss of this important surgical landmark may result in disorientation and iatrogenic trauma. The surgeon must be aware of its existence, and where it is suspected the middle fossa dura should be exposed and followed posteriorly until the lateral sinus is encountered.     

Real-Time Testing of WPT-Based Protection of Three-Phase VS PWM Inverter-Fed Motors

This paper presents an experimental testing of a wavelet packet transform (WPT)-based technique for protecting and controlling three-phase voltage-source (VS) pulse-width modulated (PWM) inverters under extreme load conditions. The proposed technique is based on a two-level multiresolution analysis (MRA) applied on output currents of a 3Phi VS PWM inverter. The MRA aims to extract certain signatures, which are the second level highest frequency subband coefficients. These coefficients take a nonzero value for any signal that is short-duration, nonperiodic and nonstationary with impulse-super imposed high frequencies. Such a signal perfectly matches a current arising from any typical fault occurring in either the inverter legs or on the load side. The proposed technique is realized using a -code hosted and executed by a dSPACE ds1102 controller board. The tested inverter supplies loads that include a 3Phi Y-connected R - L load, a 3Phi squirrel-cage induction motor and a 3Phi synchronous reluctance motor. The extreme load conditions include inverter open-leg, motor starting currents and different faults in motor stator windings. The experimental test results show accurate, fast, and effective response to all disturbances including fault currents by the proposed WPT-based technique.     

A segmentation approach for file broadcast scheduling

We study the broadcast scheduling problem in which clients send their requests to a server in order to receive some files available on the server. The server may be scheduled in a way that several requests are satisfied in one broadcast. When files are transmitted over computer networks, broadcasting the files by fragmenting them provides flexibility in broadcast scheduling that allows the optimization of per user response time. The broadcast scheduling algorithm, then, is in charge of determining the number of segments of each file and their order of transmission in each round of transmission. In this paper, we obtain a closed form approximation formula which approximates the optimal number of segments for each file, aiming at minimizing the total response time of requests. The obtained formula is a function of different parameters including those of underlying network as well as those of requests arrived at the server. Based on the obtained approximation formula we propose an algorithm for file broadcast scheduling which leads to total response time which closely conforms to the optimum one. We use extensive simulation and numerical study in order to evaluate the proposed algorithm which reveals high accuracy of obtained analytical approximation. We also investigate the impact of various headers that different network protocols add to each file segment. Our segmentation approach is examined for scenarios with different file sizes at the range of 100 KB to 1 GB. Our results show that for this range of file sizes the segmentation approach shows on average 13% tolerance from that of optimum in terms of total response time and the accuracy of the proposed approach is growing by increasing file size. Besides, using proposed segmentation in this work leads to a high Goodput of the scheduling algorithm.     

A model validation approach to texture recognition and inpainting

A new approach to texture recognition and inpainting problems is proposed. The approach is based on the robust model validation and state estimation techniques. The proposed solutions require the modeling of textures by using uncertain dynamical systems. We propose a new modeling method which is efficient in terms of computational and memory requirements. The main aspects of the modeling method include system identification and order reduction of marginally stable uncertain discrete-time systems. To demonstrate the results, both static-image textures and video textures (also known as dynamic textures) are considered.     

Two-stage Fabry-Perot filters as demultiplexers in optical FDMALANs

A high-finesse optical filter can be constructed by cascading two moderate-finesse Fabry-Perot filters of different free spectral ranges. Methods for controlling the undesirable interactions within the interfilter cavity are studied. In particular, the use of an isolator, an attenuator, or a length of fiber longer than the coherence length of the light sources used is considered. The use of a three-mirror filter, which avoids the offending cavity altogether, is also considered. The implications on the number of potential users of optical frequency-division multiple-access (FDMA), local-area networks (LANs) are also addressed     

MATRIX AND CEMENT EFFECTS ON RESIDUAL OIL SATURATION IN SANDSTONE FORMATIONS: A NEURAL NETWORK APPROACH

Abstract

Residual oil in sandstone is affected by mineral composition, clay matrix and cementing material. Matrix minerals affect the affinity of a fluid to spread on a rock surface significantly and in turn controls the fluid distribution within the pore spaces. At the interface between the rock surface and the contacting fluid, electrical charges are in the origin of the extent of phase wetness. Available framework grains, a dominant component of rock matrix, affect porosity and, hence, amounts of rock preferential wetness. Cement, clay matrix and quartz overgrowth, which make up for the rest of the grain population in a rock, influence wetness and, therefore, amounts of residual oil. In this paper, spectro-electromicroscopy (SEM) point-count technique in conjunction with neural network analysis were used to determine the effect of certains rock parameters on the amounts of residual oil following waterflooding operations. Using artifcial neural network, the intent was then to predict the extent of residual oil in sandstone rocks given limited information about rock matrix, cementing material and primary porosity.