Building test cases and oracles to automate the testing of web database applications

Many organizations rely on web applications that use back-end databases to store important data. Testing such applications requires significant effort. Manual testing alone is often impractical, so testers also rely on automated testing techniques. However, current automated testing techniques may produce false positives (or false negatives) even in a perfectly working system because the outcome of a test case depends on the state of the database which changes over time as data is inserted and deleted. The Automatic Database Tester (AutoDBT) generates functional test cases that account for database updates. AutoDBT takes as input a model of the application and a set of testing criteria. The model consists of a state transition diagram that shows how users navigate pages, a data specification that captures how data flows, and an update specification that shows how the database is updated. AutoDBT generates guard queries to determine whether the database is in a state conducive to performing and evaluating tests. AutoDBT also generates partial oracles to help validate whether a back-end database is updated correctly during testing. This paper describes the design of AutoDBT, a prototype implementation, several experiments with the prototype, and four case studies.     

Comparing Approaches for Simulating the Reactive Transport of U(VI) in Ground Water

The reactive transport of U(VI) in a well-characterized shallow alluvial aquifer at a former U(VI) mill located near Naturita, CO, was predicted for comparative purposes using a surface complexation model (SCM) and a constant K _d approach to simulate U(VI) adsorption. The ground water at the site had U(VI) concentrations that ranged from 0.01 to 20 μM, alkalinities that ranged from 2.5 to 18 meq/L, and a nearly constant pH of 7.1. The SCM used to simulate U(VI) adsorption was previously determined independently using laboratory batch adsorption experiments. Simulations obtained using the SCM approach were compared with simulations that used a constant K _d approach to simulate adsorption using previously determined site-specific K _d values. In both cases, the ground water flow and transport models used a conceptual model that was previously calibrated to a chloride plume present at the site. Simulations with the SCM approach demonstrated that the retardation factor varied temporally and spatially because of the differential transport of alkalinity and dissolved U(VI) and the nonlinearity of the U(VI) adsorption. The SCM model also simulated a prolonged slow decline in U(VI) concentration, which was not simulated using a constant K _d model. Simulations using the SCM approach and the constant K _d approach were similar after 20 years of transport but diverged significantly after 60 years. The simulations demonstrate the need for site-specific geochemical information on U(VI) adsorption to produce credible simulations of future transport.     

Electrochemical superabrasive machining of a nickel-based aeroengine alloy using mounted grinding points

Brief design and manufacture considerations are detailed for a hybrid electrochemical grinding unit adapted from a vertical machining centre using a 40,000 rpm spindle and 500 A DC generator. Subsequently, experimental work is presented on the influence of tool bond systems, superabrasive grit type and electrical parameters when simultaneous ECM/grinding Udimet 720 using 10-15 mm diameter plain points. Single layer electroplated CBN tools produced G-ratios and maximum normal cutting forces of ∼451 and ∼45 N, respectively, compared to ∼128 and 557 N for equivalent diamond wheels. Data on workpiece roughness and overcut are also presented as are initial results for a fir tree shaped tool.     

Effect of humidity and temperature on the adhesive strength of pressure sensitive adhesives

This paper reports the effect of humidity and temperature on the adhesive strength of a pressure sensitive adhesive (Flexbond 150) used to bond Mylar films. It has been found that, ill general, the adhesive strength decreases significantly with an increase in temperature. The effect of humidity on the bonding strength, however, was found to be process dependent. The sample preparation conditions, e.g., press weight for the bonding and the press time, are important in determining the humidity effect. The water sorption isotherm A 24°C for the adhesive was also determined. The amount of water sorbed by the adhesive at 95 percent relative pressure was found to be less than one weight percent.     

Intervention Schedules for Real-Time Programming

A way of programming real-time systems is described which inverts the usual image of parallel processes: instead of processes which are ordinarily running and which wait occasionally in order to synchronize with other cooperating processes, ``intervention schedules' are ordinarily waiting and run nonpreemptibly, triggered by events, which may be external (modeling hardware interrupts) or generated by other intervention schedules. In order for nonpreemptive scheduling to make sense, the maximum period of time for which any event in an intervention schedule runs must be carefully controlled. This and other aspects of the model are considered, and it is compared with more traditional models of parallel processes, and with message passing models. Programming language features to support this programmming model are discussed. Strengths and limitations of the model are discussed.     

Volatile compounds from the mite Acarus siro L. in food

The headspace above two strains of Acarus siro maintained on wheat germ/bran has been shown to contain the hydrocarbons, decane, undecane and tridecane together with the furanoid terpene, perillen. When the bodies of the separated mites were extracted with diethyl ether a new compound was found in addition to those in the headspace. This compound has been identified as 2-hydroxy-6-methyl benzaldehyde. None of these compounds appears to be responsible for the ‘minty’ smell reportedly related to mite infestation.     

Validity, predictive efficiency, and practical significance of selection tests.

The acceptance of validity coefficients at face value as measures of practical significance is evaluated by examining each functional relationship between 3 indexes of predictive efficiency r, r2, and E and 3 measures of practical significance the increase of the criterion mean, the expected proportion "satisfactory," and the expected proportion in 10 criterion categories. The validity coefficient, r is a linear function of the increase of the criterion mean and very nearly a linear function of the other 2 measures of practical significance; r2 and E are related to these 3 measures in a more curvilinear manner. A table is presented that gives the proportion expected in each of 18 criterion categories as a function of r and the selection ratio. (PsycINFO Database Record (c) 2010 APA, all rights reserved)