An Evaluation of Random Testing

Random testing of programs has usually (but not always) been viewed as a worst case of program testing. Testing strategies that take into account the program structure are generally preferred. Path testing is an often proposed ideal for structural testing. Path testing is treated here as an instance of partition testing, where by partition testing is meant any testing scheme which forces execution of at least one test case from each subset of a partition of the input domain. Simulation results are presented which suggest that random testing may often be more cost effective than partition testing schemes. Also, results of actual random testing experiments are presented which confirm the viability of random testing as a useful validation tool.     

Phase equilibria and ordering in the erbia-zirconia system

The phase diagram for the system ZrO₂-Er₂O₃ was redetermined. At high temperatures, the system is dominated by wide regions of solid solution based on ZrO₂ and Er₂O₃ separated by a two-phase field which appears to extend to the solidus. The range of existence of these solid solution fields was determined using the precision lattice parameter method. A low-temperature (<1800° C) long-range ordering occurred between 20 and 90 mol % Er₂O₃, and three ordered phases were found: the first compound was present at 40 mol % Er₂O₃ and corresponds to the ideal formula Er₄Zr₃O₁₂ with rhombohedral symmetry (space group R¯3), is isostructural with UY₆O₁₂, and decomposes at about 1500° C into fluorite solid solution by an order-disorder process; the second ordered phase is formed at about 55 mol % Er₂O₃, its formula is close to Er₅Zr₂O_11.5, and it decomposes at about 1650° C into cubic solid solutions of the fluorite and C-type; the third compound is formed at 75 mol % Er₂O₃, its formula is Er₆ZrO₁₁, it has a wide homogeneity range, and it decomposes above 1700° C into a cubic solid solution of the C-type. Liquidus determination indicated the existence of a peritectic at 62 mol % Er₂O₃.This work is based on the Ph.D. thesis of C. Pascual, Madrid University, 1980.     

Processing and Electrical Properties of 0.5Pb(Yb1/2Nb1/2)O3-0.5PbTiO3 Ceramics

Pb(Yb_1/2Nb_1/2)O₃-PbTiO₃ ceramics at the morphotropic phase boundary (50:50) were sintered by conventional and reactive methods to 95% theoretical density and grain sizes <10 m. Excess PbO, added to enhance the densification, resulted in PbO-based non-ferroelectric phases that degraded the electrical properties. Volatilization of excess PbO by annealing the samples after sintering resulted in dense, perovskite samples and excellent electrical properties. The best electrical properties, obtained via reactive sintering, were a remanent polarization, P _r, of 0.36 C/m², a maximum dielectric constant of 31,000 (at the T _c = 371°C and 1 kHz), a piezoelectric charge coefficient, d ₃₃, of 508 pC/N, and an electromechanical coupling coefficient, k ₃₃, of 0.61.     

Influence of activator on the strength and drying shrinkage of alkali-activated slag mortar

The development of new binders, as an alternative to traditional cement, by the alkaline activation of industrial by-products (i.e. ground granulated slag and fly ash) is an ongoing research topic in the scientific community [Puertas F, Amat T, Jimenez AF, Vazquez T. Mechanical and durable behaviour of alkaline cement mortars reinforced with polypropylene fibres. Cem Concr Res 2003;33(12): 2031–6]. The aim of this study was to investigate the feasibility of using and alkaline activated ground Turkish slag to produce a mortar without Portland cement (PC).Following the characterization of the slag, mortar specimens made with alkali-activated slag were prepared. Three different activators were used: liquid sodium silicate (LSS), sodium hydroxide (SH) and sodium carbonate (SC) at different sodium concentrations. Compressive and flexural tensile strength of alkali-activated slag mortar was measured at 7-days, 28-days and 3-months. Drying shrinkage of the mortar was measured up to 6-months. Setting times of the alkali-activated slag paste and PC paste were also measured.Setting times of LSS and SH activated slag pastes were found to be much slower than the setting time of PC paste. However, slag paste activated with SC showed similar setting properties to PC paste.LSS, SH and SC activated slag mortar developed 81, 29, and 36 MPa maximum compressive strengths, and 6.8, 3.8, and 5.3 MPa maximum flexural tensile strengths at 28-days. PC mortar developed 33 MPa compressive strength and 5.2 MPa flexural tensile strength. LSS and SH activated slag mortars were found to be more brittle than SC activated slag and PC mortars.Slag mortar made with LSS had a high drying shrinkage, up to six times that of PC mortar. Similarly, slag mortar made with SH had a shrinkage up to three times that of PC mortar. However, SC activated slag mortar had a lower or comparable shrinkage to PC mortar. Therefore, the use of SC as an activator for slag mortar is recommended, since it results in adequate strength, similar setting times to PC mortar and comparable or lower shrinkage.     

Market segmentation of organ donors in Egypt: a bio-inspired computational intelligence approach

First performed in 1954, organ transplantation is a universally practiced clinical procedure. This study uses ant colony optimization (ACO), radial basis function neural network (RBFNN), Kohonen’s self-organizing maps (SOM), and support vector machines (SVMs) to examine the effect of various cognitive, psychographic, and attitudinal factors on organ donation. ACO, RBFNN, SOM, and SVMs are compared to a standard statistical method (linear discriminant analysis [LDA]). The variable sets considered are altruistic values, perceived risks/benefits, knowledge, attitudes toward organ donation, and intention to donate organs. The paper shows how it is possible to identify various dimensions of organ donation behavior by uncovering complex patterns in the dataset and also shows the classification and clustering abilities of machine-learning systems.     

Sensorless control of induction motors by artificial neuralnetworks

In this letter, we propose a voltage-source inverter control working in the open loop of an induction motor measuring the stator current and using an artificial neural network. This technique has the mission to estimate the speed and torque of the rotor without using sensors. With this, a simple and cheap method of control is obtained, with as much precision and robustness as other more complex ones     

Ant colony optimization approach for classification of occupational low back disorder risks

Manual material handling (MMH) tasks, the leading cause of low back disorders (LBDs), are still extensively used in industry in spite of the advanced technology. Classification of industrial jobs related to LBD risks has great significance in preventing injuries and designing workplaces. In this article, industrial jobs have been classified into two categories, low risk and high risk, using ant colony optimization (ACO). ACO classification (ACOCLASS) has obtained better results than studies that used the same experimental data. Ergonomic interventions can be done by means of obtained classification schema for future reductions in low back injuries. © 2008 Wiley Periodicals, Inc.     

Scheduling problems with the nonlinear effects of learning and deterioration

In this paper, we present both nonlinear job deterioration and nonlinear learning which exist simultaneously. Job deterioration and learning co-exist in many realistic scheduling situations. By the effects of learning and deterioration, we mean that the processing time of a job is defined by the increasing function of its execution start time and position in the sequence. The following objectives are considered: single-machine makespan and sum of completion times (square) and the maximum lateness. For the single-machine case, we derive polynomial time optimal solutions. For the case of an m-machine permutation flowshop, we present polynomial time optimal solutions for some special cases of the problems to minimize makespan and total completion time.     

PARSEC-process analysis with recipe support for etcher control

The authors describe PARSEC, a system developed to automate processing, perform endpoint signal analysis, and monitor wafer movement within the plasma area. The system provides automatic downloading of process recipes, detection of defined process problems by the automated analysis of endpoint signals, automatic archiving of these signals, and automated data logging for increased lot-tracking efficiency. The system hardware, software, support tools, implementation, performance and results are described