General-purpose Test Research Articles

A Statistical Challenge: Developing Tests for Biomarker Utility Specific to the Intended Use

A Statistical Challenge: Developing Tests for Biomarker Utility Specific to the Intended Use

Measurement of polarization of 3He with mobile polarized 3He neutron spin filter

A mobile polarized 3He neutron spin filter was developed for both optical pumping and transportation, and the polarization of 3He was measured with cold neutrons of HANARO in KAERI. The progress of polarization build-up during the optical pumping of the 3He cell was observed by adiabatic fast-passage NMR system. The 3He cell was made of an alumino-silicate glass GE-180 with a cylindrical shape of 40mm in diameter and 60mm in length from KEK. A cell contained 5.74bar⋅cm of 3He gas. The whole installation after 8h pumping was transported to the general-purpose test station of the HANARO research reactor and the polarization of 3He was measured with cold neutrons. The measured polarization of 3He was 0.18±0.01 by measuring the neutron transmission through the 3He cell.

The Contribution of Test and Analysis to the No Fault Found (NFF) Issue within the UK MOD

This paper is a study of NFF and investigates the issue within the UK MOD with particular regard to test and analysis. A select group of people, who provide support to equipment used by the Army in the frontline, were interviewed to find out how various aspects of test and analysis contributed to NFF. The findings included, inadequate maintainer training, poor fault reporting systems, ineffective test procedures and many more. However, from the causes identified, operational pressure was the main driver and caused lack of communication between the operators and maintainers invariably leading to false diagnosis. Operational pressure also contributed to lack of sufficient diagnostic time that a maintainer had to find the root cause of a fault leading to speculative changes of Line Replaceable Units (LRUs). In both cases this would result in NFF. Anecdotal evidence suggests that a NFF rate of about 25% per LRU is being experienced with Urgent Operational Requirements (UORs). It was a problem that the Army were beginning to recognise and apply measures to reduce NFF at the frontline. This includes Automatic Test Equipment and Special to Type Test Equipment (STTE). However, STTE can be expensive to support and it is MOD policy to reduce proliferation of bespoke solutions and to use general purpose test equipment wherever possible. In order to accomplish this, MOD policy mandates the use of test standards but not all industry suppliers are keen to adopt standards as their perception was that there would be a potential loss of business.

Software Platform for General Purpose Test and Diagnosis

This paper centers on the software reuses of Automatic Test Systems (ATS) and the integration of test and diagnosis to reduce maintenance costs. Based on the research into the basic framework, data services, packages and definition of interfaces, we present an integrated software platform for test and diagnosis system. The platform achieves the separation between the user interface and test logic, the combination of fault modeling and diagnostic reasoning, and the integration of test and diagnosis.

How should we assess the fit of Rasch-type models? Approximating the power of goodness-of-fit statistics in categorical data analysis.

We investigate the performance of three statistics, R1, R2 (Glas in Psychometrika 53:525-546, 1988), and M2 (Maydeu-Olivares & Joe in J. Am. Stat. Assoc. 100:1009-1020, 2005, Psychometrika 71:713-732, 2006) to assess the overall fit of a one-parameter logistic model (1PL) estimated by (marginal) maximum likelihood (ML). R1 and R2 were specifically designed to target specific assumptions of Rasch models, whereas M2 is a general purpose test statistic. We report asymptotic power rates under some interesting violations of model assumptions (different item discrimination, presence of guessing, and multidimensionality) as well as empirical rejection rates for correctly specified models and some misspecified models. All three statistics were found to be more powerful than Pearson's X(2) against two- and three-parameter logistic alternatives (2PL and 3PL), and against multidimensional 1PL models. The results suggest that there is no clear advantage in using goodness-of-fit statistics specifically designed for Rasch-type models to test these models when marginal ML estimation is used.

Integrated language definition testing

The reliability of compilers, interpreters, and development environments for programming languages is essential for effective software development and maintenance. They are often tested only as an afterthought. Languages with a smaller scope, such as domain-specific languages, often remain untested. General-purpose testing techniques and test case generation methods fall short in providing a low-threshold solution for test-driven language development. In this paper we introduce the notion of a language-parametric testing language (LPTL) that provides a reusable, generic basis for declaratively specifying language definition tests. We integrate the syntax, semantics, and editor services of a language under test into the LPTL for writing test inputs. This paper describes the design of an LPTL and the tool support provided for it, shows use cases using examples, and describes our implementation in the form of the Spoofax testing language.

Data warehouse testing: A prototype-based methodology

Context Testing is an essential part of the development life-cycle of any software product. While most phases of data warehouse design have received considerable attention in the literature, not much has been written about data warehouse testing. Objective In this paper we propose a comprehensive approach to testing data warehouse systems. Its main features are earliness with respect to the life-cycle, modularity, tight coupling with design, scalability, and measurability through proper metrics. Method We introduce a number of specific testing activities, we classify them in terms of what is tested and how it is tested, and we show how they can be framed within a prototype-based methodology. We apply our approach to a real case study for a large retail company. Results The case study we faced, based on an iterative prototype-based medium-size project, confirmed the validity of our approach. In particular, the main benefits were obtained in terms of project transparency, coordination of the development team, and organization of design activities. Conclusion Though some general-purpose testing techniques can be applied to data warehouse projects, the effectiveness of testing can be largely improved by applying specifically-devised techniques and metrics.

V band scanner system based on ball grid array-integrated circuit transceiver chip set automation

The authors present and experimentally evaluate a scheme for measuring the frequency response of propagation channels and frequency-selective surfaces (FSSs) from 56.5–62 GHz in the US-defined license-free industrial, scientific and medical band using a commercially available millimeter-wave transceiver chip set. The authors exploit the chipset's IQ modulation scheme to produce a single sideband signal that allows the magnitude of the baseband signal to be correlated to the carrier power. Data can be recorded at 600 different frequencies in the band in 130 s, while the fastest scan the authors demonstrate gives 12 frequency points in 2.6 s. The authors expect that further savings can be made by miniaturising the system and eliminating latency associated with the use of general-purpose test equipment. Hence, it is expected that a fast, portable device for the identification of hidden millimetre-wave security labels, based on FSSs, can be constructed from this architecture.

Modeling of Test Resource Based on Multi-Agent and its Application in Intelligent Virtual Instrument

Because of the poor reconfigurability of the existing test resource models and the faultiness of the intelligent modeling methods in automatic test system, the modeling method based on Multi-Agent was studied. By analyzing the characters of test resources, the test resource models were classified as device model, adapter model and configuration model. The typical test resource model based on Multi-Agent with three layers and five agents was built. The structure and function of system management agent, model reconfiguration agent, function management agent, channel control agent and function realization agent in the model were analyzed. Then its application in Intelligent Virtual Instrument was introduced. This model based on Multi-Agent has good reconfigurability and intelligence, and it can be used to build the general-purpose and intelligent automatic test system.

Study on Universal Testing Platform of Engineering Machinery

Due to the multiple types and complexity of fault diagnosis, the general-purpose testing platform of engineering machinery’s hydraulic system is developed for the maintenance of military equipment. The general function and structure of the testing platform is presented. The hardware system consists of modular circuit, integrates control computer of embedded controller with PXI-interfaced modular instrument, program-controlled device, connector and adapter hardware. And the software program comprises data management module, fault diagnosis module coupled to the data acquisition module, signal processing module, experiment condition control module, database access module, system configuration and self-test as well as help module. Further, the hardware characteristics are showed and the principle of hydraulic testing platform is presented. The universal testing platform offers enormous benefits for fault diagnosis and condition monitoring of military equipment and machinery.

Implementing serial bus interfaces using general purpose digital instrumentation

While a dedicated test instrument can offer more targeted test capabilities for serial bus interfaces, a solution built around a general-purpose digital test instrument can offer flexibility that is unmatched in a dedicated bus test tool. This includes the flexibility to adapt to multiple bus environments, adapt to changing test conditions, support non-standard protocols (data rates, timing, or message sizes), provide synchronization for external equipment to time-specific bus events, as well as support other static and dynamic digital test needs. A general purpose solution can reduce the footprint of the test system and reduce the test equipment learning curve as the test engineer is working with one instrument or learning one programming language. Supporting multiple serial busses with one general-purpose instrument also means that the test engineer needs to interface with only one vendor should technical support be required. Finally, significant cost savings can be realized as the number of different bus protocols that need to be supported increases, while the hardware investment does not. Ultimately, the goal is to identify those instances where the clever or novel application of a general-purpose digital test tool is appropriate and provides tangible benefits in time, cost flexibility and effective utilization of resources.

A general-purpose parallel raster processing programming library test application using a geographic cellular automata model

A general-purpose parallel raster processing programming library (pRPL) was developed and applied to speed up a commonly used cellular automaton model with known tractability limitations. The library is suitable for use by geographic information scientists with basic programming skills, but who lack knowledge and experience of parallel computing and programming. pRPL is a general-purpose programming library that provides generic support for raster processing, including local-scope, neighborhood-scope, regional-scope, and global-scope algorithms as long as they are parallelizable. The library also supports multilayer algorithms. Besides the standard data domain decomposition methods, pRPL provides a spatially adaptive quad-tree-based decomposition to produce more evenly distributed workloads among processors. Data parallelism and task parallelism are supported, with both static and dynamic load-balancing. By grouping processors, pRPL also supports data–task hybrid parallelism, i.e., data parallelism within a processor group and task parallelism among processor groups. pSLEUTH, a parallel version of a well-known cellular automata model for simulating urban land-use change (SLEUTH), was developed to demonstrate full utilization of the advanced features of pRPL. Experiments with real-world data sets were conducted and the performance of pSLEUTH measured. We conclude not only that pRPL greatly reduces the development complexity of implementing a parallel raster-processing algorithm, it also greatly reduces the computing time of computationally intensive raster-processing algorithms, as demonstrated with pSLEUTH.

Model-Driven Visual Testing and Debugging of WSN Applications

We introduce our tool-suite that facilitates automated testing of applications for wireless sensor networks (WSNs). WSNs are highly distributed systems and therefore require a testing infrastructure. We present a general-purpose testing framework which enables component, integration, and system testing. When using our testing framework, test cases have to be implemented by several modules. To coordinate the execution of these modules synchronization code must be written which is a complex and time consuming task. To bypass this task and thus make the test case implementation process more efficient, we introduce a model-driven approach that delegates this task to the code generator. Thereto, the test scenario is represented in a model and the code of the modules is generated. This model also eases the task of isolating faults in the code of the application being tested because the model can be refined to get insights on the application’s behavior to backtrack the cause of the failure reproduced by the test case.

Issues in using model checkers for test case generation

The use of model checkers for automated software testing has received some attention in the literature: It is convenient because it allows fully automated generation of test suites for many different test objectives. On the other hand, model checkers were not originally meant to be used this way but for formal verification, so using model checkers for testing is sometimes perceived as a “hack”. Indeed, several drawbacks result from the use of model checkers for test case generation. If model checkers were designed or adapted to take into account the needs that result from the application to software testing, this could lead to significant improvements with regard to test suite quality and performance. In this paper we identify the drawbacks of current model checkers when used for testing. We illustrate techniques to overcome these problems, and show how they could be integrated into the model checking process. In essence, the described techniques can be seen as a general road map to turn model checkers into general purpose testing tools.

A General Purpose Test Facility for Evaluating Gas Lubricated Journal Bearings

The present work describes the detailed design and operational capabilities of a general purpose test facility developed to evaluate the dynamics and performance of gas lubricated journal bearings. The component level test facility was developed to serve as an initial tollgate test platform for certifying gas lubricated journal bearings into aircraft engine applications. A rotating test rig was engineered to test 70–120 mm diameter bearings at 40,000–80,000 rpm and 1200°F. The test rig described in this paper possesses design elements that enable the simultaneous application of dynamic and static load profiles of up to 1000 lb while monitoring and measuring the bearing torque. This capability allows for the characterization of several critical metrics such as bearing lift off speed characteristics, load capacity, and frequency dependent rotordynamic force coefficients. This paper discusses the functionality of the test facility and presents sample test measurements from several experiments.

Robust detection of periodic time series measured from biological systems

BackgroundPeriodic phenomena are widespread in biology. The problem of finding periodicity in biological time series can be viewed as a multiple hypothesis testing of the spectral content of a given time series. The exact noise characteristics are unknown in many bioinformatics applications. Furthermore, the observed time series can exhibit other non-idealities, such as outliers, short length and distortion from the original wave form. Hence, the computational methods should preferably be robust against such anomalies in the data.ResultsWe propose a general-purpose robust testing procedure for finding periodic sequences in multiple time series data. The proposed method is based on a robust spectral estimator which is incorporated into the hypothesis testing framework using a so-called g-statistic together with correction for multiple testing. This results in a robust testing procedure which is insensitive to heavy contamination of outliers, missing-values, short time series, nonlinear distortions, and is completely insensitive to any monotone nonlinear distortions. The performance of the methods is evaluated by performing extensive simulations. In addition, we compare the proposed method with another recent statistical signal detection estimator that uses Fisher's test, based on the Gaussian noise assumption. The results demonstrate that the proposed robust method provides remarkably better robustness properties. Moreover, the performance of the proposed method is preferable also in the standard Gaussian case. We validate the performance of the proposed method on real data on which the method performs very favorably.ConclusionAs the time series measured from biological systems are usually short and prone to contain different kinds of non-idealities, we are very optimistic about the multitude of possible applications for our proposed robust statistical periodicity detection method.AvailabilityThe presented methods have been implemented in Matlab and in R. Codes are available on request. Supplementary material is available at: .

Testing time symmetry in time series using data compression dictionaries.

Time symmetry, often called statistical time reversibility, in a dynamical process means that any segment of time-series output has the same probability of occurrence in the process as its time reversal. A technique, based on symbolic dynamics, is proposed to distinguish such symmetrical processes from asymmetrical ones, given a time-series observation of the otherwise unknown process. Because linear stochastic Gaussian processes, and static nonlinear transformations of them, are statistically reversible, but nonlinear dynamics such as dissipative chaos are usually statistically irreversible, a test will separate large classes of hypotheses for the data. A general-purpose and robust statistical test procedure requires adapting to arbitrary dynamics which may have significant time correlation of undetermined form. Given a symbolization of the observed time series, the technology behind adaptive dictionary data compression algorithms offers a suitable estimate of reversibility, as well as a statistical likelihood test. The data compression methods create approximately independent segments permitting a simple and direct null test without resampling or surrogate data. We demonstrate the results on various time-series-reversible and irreversible systems.

Mechanical testing device for in situ experiments on reversibility of dislocation motion in silicon

We present a general-purpose mechanical testing device built and tested for in situ experiments using synchrotron radiation. A new setup was used in order to investigate the reversibility of dislocation motion under stress reversal. The observations were done by in situ transmission X-ray topography, at the ID 19 beamline of the ESRF. Specimens of FZ silicon single crystals, with a [ 1 1 ̄ 4 ] axis (double slip orientation), were submitted to load cycles in tension and compression ( τ=10–20 MPa) at high temperature (650–750 °C). Dislocations were created at surfaces by Vickers indents. They were observed using a monochromatic beam ( λ=0.035 nm) and a 220 diffraction vector. The images were recorded both on X-ray films and using the FRELON X-ray camera. The first observations show that dislocations may behave in different ways within the same specimen, and that their motion can be partially reversible.

Loop Bandwidth Optimization and Jitter Measurement Techniques for Serial HDTV Systems

This paper describes a system level optimization of a studio serial digital interface for uncompressed high-definition television (HDTV). The HDTV data rate is 5.5 times that of standard-definition television (SDTV) which allows little design margin for jitter. An intuitive time domain discussion of different sources of jitter is presented. The paper provides design guidelines for video sources, routers, digital signal processing units with serial interface, distribution amplifiers, and production switchers. These guidelines reinforce the SMPTE 292M standard and other recommended practices, for example, EG 33–1998. Using commercially available general-purpose test units and some custom built boards, it is shown that some of the important jitter parameters associated with serial HDTV can be easily measured.

A test for symmetries of multivariate probability distributions

A Monte Carlo test for multivariate symmetries is proposed. The Monte Carlo simulations are performed conditionally on a minimal sufficient statistic for the class of distributions with symmetric density. Additionally, a general purpose test statistic based on a distance measure between the probability density function and its symmetrised version is introduced. The Monte Carlo tests for spherical symmetry and multivariate reflection symmetry are studied numerically for this statistic and the results indicate that the tests perform well compared to other tests. The method is illustrated with an analysis of a real dataset.