Specific Test Case Research Articles

Dynamic impact analysis

This paper introduces dynamic impact analysis as a cost-effective technique to enforce the error-propagation condition for detecting a fault. The intuition behind dynamic impact analysis is as follows. In a specific test-case, if an execution of a syntactic component has a strong impact on the program output and if the output is correct, then the value of that component-execution is not likely to be erroneous. To capture this intuition in a theoretical framework the notion of impact is formally defined and the concept of impact strength is proposed as a quantitative measure of the impact. In order to provide an infrastructure supporting the computation of impact strengths, program impact graphs and execution impact graphs are introduced. An empirical study validating the computation of impact strengths is presented. It is shown that the impact strengths computed by dynamic impact analysis provide reasonable estimates for the error-sensitivity with respect to the output except when the impact is via one or more error-tolerant components of the program. Potential applications of dynamic impact analysis in the area of mutation testing and dynamic program slicing are discussed.

Test case verification by model checking

Verification of a test case for testing the conformance of protocol implementations against the formal description of the protocol involves verifying three aspects of the test case: expected input/output test behavior, test verdicts, and the test purpose. We model the safety and liveness properties of a test case using branching time temporal logic. There are four types of safety properties: transmission safety, reception safety, synchronization safety, and verdict safety. We model a test purpose as a liveness property and give a set of notations to formally specify a test purpose. All these properties expressed as temporal formulas are verified using model checking on an extended state machine graph representing the composed behavior of a test case and protocol specification. This methodology is shown to be effective in finding errors in manually developed conformance test suites.

Verification of protocol conformance test cases using reachability analysis

A methodology is presented to verify manually written test cases against the formal specification of a protocol. Initially, a protocol and a test case are modeled as nondeterministic finite state machines and test case verification is viewed as a reachability analysis problem. An existing reachability analysis algorithm, based on the well-known perturbation technique, is modified to take nondeterminism in protocols and special test case features (timeouts and OTHERWISE events) into account. Correctness aspects of the reachability algorithm are proved. The notion of a synchronization error manifesting in a test case due to the nondeterministic nature of a protocol specification is studied. To verify data flow aspects of test cases, we extend our technique by modeling the test case and protocol specification as extended finite state machines. A test case from a proprietary test suite for the transport protocol Class 2 is taken as an example and is shown to contain several design errors.

Taxonomic performance evaluation for multitarget tracking systems

A scoring scheme based on an object track classification which facilitates performance evaluation for multiple-target tracking systems is derived and applied to specific test cases involving a comparison of operational and modified tracking system performance. The performance measures derived can be applied both to comparative evaluations of tracking system alternatives where relative performance is the issue, and to evaluations of system performance relative to what can be achieved in any given target object environment. >

Abutment of high energy electron fields

The problem of positioning multiple electron fields on the skin surface is complicated by the fact that the scattering properties of electrons result in constriction of the higher value isodoses and bulging out of the lower value isodoses. We have studied the dose distributions in the junction region for adjacent electron fields using our 3-dimensional radiation treatment planning system by investigating the effects of field separation for several field size, air gap, and beam energy combinations. Film dosimetry was used to measure specific test cases. Using our 3-dimensional radiation treatment planning system, we are able to display the calculated dose distribution, calculate dose-volume histograms, and compare calculations with the film dosimetry measurements. Results of our study are presented.

An intercomparison of the accuracy of computer planning systems for brachytherapy

The accuracy of brachytherapy computer planning systems has been investigated by means of an intercomparison of the dose distributions as calculated by these systems for five specific test cases. In this intercomparison, 13 radiotherapy institutions in The Netherlands participated. The planning systems evaluated comprise all commercial systems in clinical use in The Netherlands (different versions of in total four manufacturers) as well as in-house developed systems. The five test cases were designed in order to quantify the errors introduced by: (a) the calculation algorithm including the method of source specification used; (b) the localisation procedure via orthogonal radiographs; and (c) the clinical dose specification system in the case of a geometrically irregular implantation for which no established, rigid dose specification method is available. The results of this comparison can be summarized as follows: The accuracy of most calculation algorithms appears to be satisfactory except for the region close to the longitudinal axis of linear sources. Source strength specification in terms of activity or milligram radium equivalent can result in dosimetric errors which may be clinically relevant and therefore specification of the source strength in terms of “output”, i.e. air-kerma rate at a specified distance, is to be preferred. This concurs with recent national and international recommendations regarding source strength specification. Localisation via orthogonal radiographs, as commonly used, appears to cause noticeable errors. This aspect could be improved in a quality assurance program. In case of “irregular” implantations, the uncertainty in clinical dose specification clearly dominates the overall accuracy. This illustrates the need for a consistent dose specification system, which is capable of including interstitial implants with a source geometry deviating from the rules given by the existing specification systems. It can be concluded that in brachytherapy, whenever possible, a well-defined, rigid clinical dose specification system should be applied, but that even in such cases the delivered dose may be in error by more than 5% (1 S.D.).

An evaluation of methods for the estimation of tributary mass loads

Tributary loading estimation methods were evaluated by conducting retrospective studies with comprehensive sets of field data for flow rates, nutrients, heavy metals, and polychlorinated biphenyls. Three broad classes of loading estimation methods were investigated: simple averaging methods, ratio estimation methods, and regression methods. Estimators were evaluated using Monte Carlo sampling studies in which random subsamples of complete loading records were used to estimate annual loadings. These estimates were then compared to “true” loadings determined by calculations using the entire record. No group of estimators were found to be superior for all test cases considered. However, individual estimation approaches within each group often provided low error estimates. Results were inconsistent among test cases and these inconsistencies appeared to be related to specific test case characteristics such as the strength and form of the flow‐concentration relationship and the nature of the annual hydrograph. Ratio estimators appeared to be more robust to sources of bias than other estimation approaches.

Selective isolation of newly synthesized mammalian mRNA after in vivo labeling with 4-thiouridine or 6-thioguanosine

Newly synthesized mRNA from hamster cells was labeled in vivo with the thionucleoside analogs 4-thiouridine (4-TU) and 6-thioguanosine (6-TG). The thio-substituted RNA was selectively recovered by Affi-Gel 501 phenylmercury affinity chromatography. Following a 1-h labeling period, enrichment for newly transcribed RNA after a single round of chromatography ranged between 10- and 15-fold when compared with total RNA. Exposure of CHO UrdA − cells, a uridine auxotrophic line, to 50 μ m 4-TU allowed for optimal recovery of newly transcribed RNA. Increasing the concentration of 4-TU to 100 μ m or labeling with 6-TG at concentrations of 3 μ m or greater resulted in similar recoveries from uridine-prototrophic hamster cell lines. For shorter term labeling, exposure of prototrophic cells to 500 μ m 4-TU or 100 μ m 6-TG for 15 min allowed newly synthesized RNA to be selectively recovered. As a specific test case, enrichment for histone H3.2 mRNA was analyzed after hamster cells were labeled with 4-TU under conditions in which the gene was highly transcriptionally active. Northern blot analysis and the specific activity of thio-substituted RNA revealed a 15-fold enrichment when compared to total RNA. In vivo labeling of cellular RNA with 4-TU or 6-TG should provide a useful method for studying inducible gene expression and for isolating and cloning specific mRNAs from mammalian cells.

Timing variation in dual loop benchmark

Benchmarks that measure time values using a standard system clock often employ a dual loop design. One of the important assumptions of this design is that textually identical loop statements will take the same amount of time to execute. This assumption has been tested on two bare computers with Ada® test programs and has been demonstrated to be inaccurate in these specific test cases.

New approaches to the characterization and classification of ceramics on the basis of their elemental composition

This study is a part of a larger investigation related to questions of the systemization of neutron activation analysis results. It considers the analysis of experimental data and focuses on the application of a multivariate statistical technique to the characterization and classification of ceramic artifacts in order to establish and assess their provenance. Central to the statistical methodology reported here is the determination of a specific characterization-classification function. This function provides a method of defining a group of archaeological ceramics on the basis of their elemental composition patterns. Conditional and expected probabilities calculated from the function are then used as a means of classifying unknown observations, indicating outliers, and detecting the existence of another group as yet unidentified. The utility of the function is demonstrated in a specific test case. The possibility of using the characterization-classification function to increase the portability of information and to reduce the need for centralized computer data banks is pointed out.

Energetics of multihelix interactions in protein folding: application to myoglobin.

AbstractConformational‐energy calculations have been carried out in order to determine favorable packing arrangements within a group of α‐helices. The influence of side chains and of the number of interacting α‐helices on the mode of packing was analyzed. In this work, our earlier methods for computing the packing energy of a pair of α‐helices [Chou, K.‐C., Némethy, G. & Scheraga, H. A. (1984) J. Am. Chem. Soc. 106, 3161–3170] have been extended to treat the interactions among several helices. Also, new algorithms allow the matching of standard peptide geometry to x‐ray coordinates of helical complexes and the analysis of interrelations between several helices. As a specific test case, the packing of three neighboring α‐helices, viz., the A, G, and H helices of sperm whale myoglobin, was considered. Minimum‐energy arrangements were computed for the separate A‐H and the G‐H α‐helix pairs as well as for the A‐G‐H three‐helix complex. For the packing of the nearly antiparallel G and H α‐helices, the same optimal structure was obtained in two‐ and three‐helix complexes, indicating that a single packing arrangement is specifically favored by interhelix interactions. For the pair of nearly perpendicular A and H α‐helices, interactions are less specific, so that there is no unique optimal structure in the two‐helix complex; in the three‐helix complex, however, a specific mode of packing is favored even for the A‐H pair. This result indicates that the presence of other nearby α‐helices can influence the packing of a given α‐helix pair. The computed arrangement of the A‐G‐H complex is very close to that of the crystallographically determined structure. These results can be used to make deductions about the likely sequence of events in protein folding, where, in this particular case, it appears that the G‐H helix pair may form first and then induce proper orientation of the A helix.

Generalized Euler transformation in extracting useful information from divergent (asymptotic) perturbation series and the construction of Padé approximants

AbstractEuler transformation for accelerating convergence of a series is considered in the context of handling divergent (asymptotically convergent) perturbation series. A generalized (parametrized) version of this transformation is developed, based on the conjecture of Dalgarno and Stewart, which works better. Viewed from this standpoint, the Padé approximants follow as a special case of the parametrized Euler transformation (PET), as is the case with the μ transformation procedure of Feenberg in a perturbative context. The PET is shown to serve as a more general method of handling a divergent series and is able to appreciate the construction and convergence behavior of specific sequences of Padé approximants. The role of parametrization in the context of the Z−1 perturbation theory of atoms is also noted and the workability of the adopted strategy is demonstrated by choosing some specific test cases.

Viscous-Inviscid Interaction on Oscillating Airfoils in Subsonic Flow

Abstract : Selected results from an extensive oscillating-airfoil experiment are analyzed and reviewed. Four distinct regimes of viscous-inviscid interaction are identified, corresponding to varying degrees of unsteady flow separation. The dominant fluid dynamic phenomena are described for each regime. Ten specific test cases, including the appropriate flow conditions and experimental results, are proposed for evaluating unsteady viscous theories and computational methods. (Author)

The softest program test system

This paper reviews the current status of both research and commercial testing systems, and addresses the features necessary for a commercial test system. These include test case specification, test data generation, testbed generation, program instrumentation, automatic test execution and validation, as well as dynamic analysis of control and data flow. Of particular value is the linking of the details of the test to the program specification by means of an assertion language. These and other features are then described within the contest of softest, an integrated system for testing Assembler, cobol, and pl/ 1 programs in a simulated test environment. This system is now being used to validate programs in a test laboratory.

Dielectric band structure of crystals: General properties and calculations for silicon

We develop the dielectric band-structure method, originally proposed by Baldereschi and Tosatti, for the description of microscopic electronic screening in crystals. Some general properties are examined first, including the requirements of causality and stability. The specific test case of silicon is then considered. Dielectric bands are calculated, according to several different prescriptions for the construction of the dielectric matrix. It is shown that the results allow a very direct appraisal of the screening properties of the system, as well as of the quality of the dielectric model adopted. The electronic charge displacement induced by ${\ensuremath{\Gamma}}_{25}^{\ensuremath{'}}$ and ${X}_{3}$ phononlike displacements of the atoms is also calculated and compared with the results of existent fully self-consistent calculations. Conclusions are drawn on the relative accuracies of the dielectric band structures.

Quasisteady primitive equations with associated upper boundary conditions

This paper presents another approach to the problem of modeling large scale atmospheric flow. The major thrust of the method is to search for quasi-steady-state phenomena. This leads to sets of diagnostic and predictive equations that differ from those presently in use. Another important feature of the analysis is the introduction of a slowly floating upper boundary. In addition to simplifying the question of boundary conditions at the upper boundary, the floating top requires a highly significant change in the set of diagnostic variables. Two possible upper boundary conditions are derived in conjunction with the floating top. The first assumes continuous flow at the upper boundary, while the second assumes a compression-wave type discontinuity. Two specific criteria are formulated for checking the validity of the quasi-steady-state model. One is a scale assumption, between the physical scale and the time scale. The other is the requirement that the solution of the diagnostic equations be the steady-state limit of the original time-dependent equations. Various examples are given in order to attempt to clarify the techniques and philosophy of this approach. In addition, a specific test case is solved numerically with three models: The fixed top quasi-steady-state model, the floating top quasi-steady-state model, and a hydrostatic model. At the same time various upper boundary conditions are tested and compared. The results of the investigation indicate several significant advantages in favor of the floating top quasi-steady-state model.