Estimating the feasibility of transition paths in extended finite state machines

There has been significant interest in automating testing on the basis of an extended finite state machine (EFSM) model of the required behaviour of the implementation under test (IUT). Many test criteria require that certain parts of the EFSM are executed. For example, we may want to execute every transition of the EFSM. In order to find a test suite (set of input sequences) that achieves this we might first derive a set of paths through the EFSM that satisfy the criterion using, for example, algorithms from graph theory. We then attempt to produce input sequences that trigger these paths. Unfortunately, however, the EFSM might have infeasible paths and the problem of determining whether a path is feasible is generally undecidable. This paper describes an approach in which a fitness function is used to estimate how easy it is to find an input sequence to trigger a given path through an EFSM. Such a fitness function could be used in a search-based approach in which we search for a path with good fitness that achieves a test objective, such as executing a particular transition, and then search for an input sequence that triggers the path. If this second search fails then we search for another path with good fitness and repeat the process. We give a computationally inexpensive approach (fitness function) that estimates the feasibility of a path. In order to evaluate this fitness function we compared the fitness of a path with the ease with which an input sequence can be produced using search to trigger the path and we used random sampling in order to estimate this. The empirical evidence suggests that a reasonably good correlation (0.72 and 0.62) exists between the fitness of a path, produced using the proposed fitness function, and an estimate of the ease with which we can randomly generate an input sequence to trigger the path

Using genetic algorithms to generate test sequences for complex timed systems

The generation of test data for state based specifications is a computationally expensive process. This problem is magnified if we consider that time con- straints have to be taken into account to govern the transitions of the studied system. The main goal of this paper is to introduce a complete methodology, sup- ported by tools, that addresses this issue by represent- ing the test data generation problem as an optimisa- tion problem. We use heuristics to generate test cases. In order to assess the suitability of our approach we consider two different case studies: a communication protocol and the scientific application BIPS3D. We give details concerning how the test case generation problem can be presented as a search problem and automated. Genetic algorithms (GAs) and random search are used to generate test data and evaluate the approach. GAs outperform random search and seem to scale well as the problem size increases. It is worth to mention that we use a very simple fitness function that can be eas- ily adapted to be used with other evolutionary search techniques

Spectrophotometric determination of trace amounts of platinum (IV) with iodide and rhodamine 6G

1103-1105A sensitive and selective procedure for spectrophotometric determination of platinum (IV) with rhodamine 6G in presence of iodide has been described. The absorbance is measured at 575 nm and the molar absorptivity is found to be 1.26x 105 1 mol-1cm-1. The complex system obeys Beer's law in the range 0-12 mg of platinum (IV) present in 25 ml of final solution. The effect of pH and concentration of iodide and rhodamine 6G have been studied. The method has been applied successfully to the determination of platinum (IV) in the standard platinum carbon powder (platinum catalyst)

Spectrophotometric determination of trace amounts of palladium(ll) using iodide and rhodamine 6G

342-343A sensitive and highly selective procedure for the spectrophotometric determination of palladium(II) is described. The method is based on the formation of ternary ion-association complex, Pd-I - -rhodamine 6G, in a citrate buffered medium. The colour system absorbs maximally at 575 nm with molar absorptivity of 8.2 x 104 1 mol- 1 cm - 1 and obeys Beer's law in the range 1-10 mg. The method has been applied successfully to the determination of palladium(II) in synthetic mixtures and in standard palladium activated charcoal

Confirming configurations in EFSM

In this paper we investigate the problem of configuration distinguishability for the EFSM model, specifically, given a configuration and an arbitrary set of configurations, determine an input sequence such that the EFSM in the given configuration produces an output sequence different from that of the configurations in the given set or at least in a maximal proper subset. Such a sequence can be used in a test case to confirm the destination configuration. We demonstrate that the distinguishability problem could be reduced to the EFSM traversal problem, so that the existing methods and tools developed in the context of model checking become applicable. The theoretical framework for determining configuration-confirming sequences based on projections and products of EFSMs is presented. Our approach can be implemented in a number of heuristic test derivation strategies

Interaction between epsomite crystals and organic additives

A number of phosphonates and carboxylates were tested as potential crystallization inhibitors for epsomite (MgSO4·7H 2O). Epsomite nucleation is strongly inhibited in the presence of amino tri(methylene phosphonic acid) (ATMP), diethylenetriaminepentakis (methylphosphonic acid) (DTPMP), and poly(acrylic acid) sodium salt (PA). These additives also act as habit modifiers promoting the growth of acicular crystals elongated along the [001] direction. Environmental scanning electron microscopy (ESEM), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and molecular modeling of additive adsorption on specific epsomite (hkl) faces are used to identify how these additives inhibit epsomite crystallization. Additives attach preferentially on epsomite {110} faces, at edges of monolayer steps parallel to [001]. Step pinning and the eventual arrest of step propagation along (110) directions account for the observed habit change. Hydrogen bonding between the functional groups of additive molecules and water molecules in epsomite {110} appears to be the principal mechanism of additive-epsomite interaction, as shown by FTIR and molecular modeling. Molecular modeling also shows that DTPMP displays a high stereochemical matching with epsomite {110} surfaces, which can explain why this is the most effective inhibitor tested. The use of such effective crystallization inhibitors may lead to more efficient preventive conservation of ornamental stone affected by epsomite crystallization damage. © 2008 American Chemical Society