A formal model of the software test process

A novel approach to model the system test phase of the software life cycle is presented. This approach is based on concepts and techniques from control theory and is useful in computing the effort required to reduce the number of errors and the schedule slippage under a changing process environment. Results from these computations are used, and possibly revised, at specific checkpoints in a feedback-control structure to meet the schedule and quality objectives. Two case studies were conducted to study the behavior of the proposed model. One study reported here uses data from a commercial project. The outcome from these two studies suggests that the proposed model might well be the first significant milestone along the road to a formal and practical theory of software process control.     

Wavelength conversion by four-wave mixing in semiconductor opticalamplifiers

Time-resolved spectral analysis is performed on 10 Gb/s signals wavelength converted by four-wave mixing (FWM) in semiconductor optical amplifiers. A pattern-dependent chirp resulting from parasitic gain modulation by the signal is measured and characterized as a function of the converter's pump-to-probe ratio. This chirp is found to be insignificant for pump-to-probe ratios exceeding 9 dB     

Biphenylsulfonamide endothelin antagonists: structure-activity relationships of a series of mono- and disubstituted analogues and pharmacology of the orally active endothelin antagonist 2'-amino-N- (3,4-dimethyl-5-isoxazolyl)-4'-(2-methylpropyl)[1, 1'-biphenyl]-2-sulfonamide (BMS-187308)

Substitution at the ortho position of N-(3,4-dimethyl-5-isoxazolyl) benzenesulfonamide led to the identification of the biphenylsulfonamides as a novel series of endothelin-A (ETA) selective antagonists. Appropriate substitutions on the pendant phenyl ring led to improved binding as well as functional activity. A hydrophobic group such as isobutyl or isopropoxyl was found to be optimal at the 4'-position. Introduction of an amino group at the 2'-position also led to improved analogues. Combination of the optimal 4'-isobutyl substituent with the 2'-amino function afforded an analogue (20, BMS-187308) with improved ETA binding affinity and functional activity. Compound 20 also has good oral activity in inhibiting the pressor effect caused by an ET-1 infusion in rats. Doses of 10 and 30 micromol/kg iv 20 attenuated the pressor responses due to the administration of exogenous ET-1 to conscious monkeys, indicating that the compound inhibits the in vivo activity of endothelin-1 in nonhuman primates.     

Figure-ground segregation using an analog VLSI chip

An analog, parallel, computational system, built on a single, power-lean, CMOS VLSI chip, that labels all points inside a possibly incomplete and noisy contour in real time is described. The circuit performs figure-ground segregation of a scene, labeling all the points inside a designated figure by one voltage and all other parts outside this object using a different voltage value. Its behavior is shown to be robust, since small breaks in the contour are automatically sealed, providing for figure-ground segregation in a noisy environment. The two major limitations of the current figure-ground chip are its limited capability for recognizing figures with large gaps in the contour and the constraint that the figure always has to be centered     

Computational Experience with a Dual Backtrack Algorithm for Identifying Frequencies Likely to Create Intermodulation Problems

This paper describes the results of a computational study using a particular enumeration procedure, called a backtrack algorithm, to find the lowest order of radio-frequency intermodulation. The average lowest order and its standard deviation, the average computer time and its standard deviation, along with other relevent statistics are obtained for a series of randomly generated problems with sets of five to 75 threat or source frequencies. Other parameters, such as the guard band, the maximum number of concurrent threats, and the size of the frequency band on the lowest order of intermodulation are varied during the computations. Statistics for these computer runs, along with those relating to terminating the algorithm when the lowest "acceptable" order is reached, are presented in some detail. Brief conclusions follow a listing of the results.     

Micropolar fluid jet impingement on a curved surface

This paper deals with an analysis of a normally impinging micropolar fluid jet on a curved surface. The flow near the stagnation point in the impingement region is divided into inviscid and viscous flow regions. The inviscid flow solution is governed by Euler's equations of motion expressed in curvilinear coordinate system. The viscous flow solution is governed by the zeroth and the first order boundary layer equations. These boundary layer equations are solved by assuming power series expansions for both velocity and microrotation fields which give rise to two systems of ordinary coupled differential equations. The effects of surface curvature and material parameters on boundary layer characteristics have been studied and presented graphically. The gradients of zeroth order velocity and microrotation at the wall decrease and the zeroth order displacement and momentum thicknesses increase with decrease in the value of surface curvature. The reduction in curvature results in the reduction in the gradients of first order velocity and microrotation at the wall as well as first order displacement and momentum thicknesses.     

Relation between zinc content in saliva and blood in healthy human adults

Measurements were made of zinc levels in saliva, whole blood and plasma as well as copper levels in plasma by atomic absorption spectrophotometry. The mean zinc concentration (in ppm) was 0.478 (n = 136) in resting mixed saliva, 0.046 (n = 36) in parotid saliva, 6.41 (n = 145) in whole blood and 0.87 (n = 145) in plasma. The whole blood zinc levels were significantly lower in females than in males (P less than 0.001). Females and blood donors (males) had a significantly (P less than 0.001) higher Cu:Zn ratio than males (non-donors). It would thus appear, first, that the local effect of salivary zinc cannot be assessed simply from the concentration of zinc in stimulated parotid saliva since about nine-tenths of the zinc in resting mixed saliva is derived from other sources and, second, that the Cu:Zn in plasma is the most eligible variable for detecting sub-clinical Zn deficiency.     

A kinetic study on copolymerization of styrene with methyl methacrylate in the presence of zinc chloride

The kinetics of copolymerization of styrene with methyl methacrylate in the presence of zinc chloride as a complexing agent at 50, 60 and 70°C and azobis-isobutyronitrile (AIBN) as an initiator was investigated by use of a dilatometer, modified to carry out reaction in an inert atmosphere. A ‘master graph’ has been prepared by which any volume contraction data could be converted into percentage conversion and the results used to calculate the rate of copolymerization (Rp). It has been observed that Rp is directly proportional to the concentration of initiator and methyl methacrylate but is inversely affected by the styrene concentration. Zinc chloride does not initiate the copolymerization reaction but increases Rp by increased the rate of propagation (Rp'). It does not affect either the rate of initiation (Ri) or the rate of termination (Rt) since the system attains a steady state. The rate constants and activation energy have also been calculated.