Erroneous Behavior Research Articles

Error explanation with distance metrics

In the event that a system does not satisfy a specification, a model checker will typically automatically produce a counterexample trace that shows a particular instance of the undesirable behavior. Unfortunately, the important steps that follow the discovery of a counterexample are generally not automated. The user must first decide if the counterexample shows genuinely erroneous behavior or is an artifact of improper specification or abstraction. In the event that the error is real, there remains the difficult task of understanding the error well enough to isolate and modify the faulty aspects of the system. This paper describes a (semi-)automated approach for assisting users in understanding and isolating errors in ANSI C programs. The approach, derived from Lewis’ counterfactual approach to causality, is based on distance metrics for program executions. Experimental results show that the power of the model checking engine can be used to provide assistance in understanding errors and to isolate faulty portions of the source code.

Automatically generating refactorings to support API evolution

When library APIs change, client code should change in response, in order to avoid erroneous behavior, compilation failures, or warnings. Previous research has introduced techniques for generating such client refactorings. This paper improves on the previous work by proposing a novel, lightweight technique that takes advantage of information that programmers can insert in the code rather than forcing them to use a different tool to re-express it. The key idea is to replace calls to deprecated methods by their bodies, where those bodies consist of the appropriate replacement code. This approach has several benefits. It requires no change in library development practice, since programmers already adjust method bodies and/or write example code, and there are no new tools or languages to learn. It does not require distribution of new artifacts, and a tool to apply it can be lightweight. We evaluated the applicability of our approach on a number of libraries and found it to to be applicable in more than 75% of the cases.

Is Hairpin Formation in Single-Stranded Polynucleotide Diffusion-Controlled?

An intriguing puzzle in biopolymer science is the observation that single-stranded DNA and RNA oligomers form hairpin structures on time scales of tens of microseconds, considerably slower than the estimated time for loop formation for a semiflexible polymer of similar length. To address the origin of the slow kinetics and to determine whether hairpin dynamics are diffusion-controlled, the effect of solvent viscosity (eta) on hairpin kinetics was investigated using laser temperature-jump techniques. The viscosity was varied by addition of glycerol, which significantly destabilizes hairpins. A previous study on the viscosity dependence of hairpin dynamics, in which all the changes in the measured rates were attributed to a change in solvent viscosity, reported an apparent scaling of relaxation times (tau(r)) on eta as tau(r) approximately eta(0.8). In this study, we demonstrate that if the effect of viscosity on the measured rates is not deconvoluted from the inevitable effect of change in stability, then separation of tau(r) into opening (tau(o)) and closing (tau(c)) times yields erroneous behavior, with different values (and opposite signs) of the apparent scaling exponents, tau(o) approximately eta(-0.4) and tau(c) approximately eta(1.5). Under isostability conditions, obtained by varying the temperature to compensate for the destabilizing effect of glycerol, both tau(o) and tau(c) scale as approximately eta(1.1+/-0.1). Thus, hairpin dynamics are strongly coupled to solvent viscosity, indicating that diffusion of the polynucleotide chain through the solvent is involved in the rate-determining step.

Exploiting purity for atomicity

Multithreaded programs often exhibit erroneous behavior because of unintended interactions between concurrent threads. This paper focuses on the noninterference property of atomicity. A procedure is atomic if, for every execution, there is an equivalent serial execution in which the actions of the atomic procedure are not interleaved with actions of other threads. This key property makes atomic procedures amenable to sequential reasoning techniques, which significantly facilitates subsequent validation activities such as code inspection and testing. Several existing tools verify atomicity by using commutativity of actions to show that every execution reduces to a corresponding serial execution. However, experiments with these tools have highlighted a number of interesting procedures that, while intuitively atomic, are not reducible. In this paper, we exploit the notion of pure code blocks to verify the atomicity of such irreducible procedures. If a pure block terminates normally, then its evaluation does not change the program state and, hence, these evaluation steps can be removed from the program trace before reduction. We develop a static typed-based analysis for atomicity based on this insight, and we illustrate this analysis on a number of interesting examples that could not be verified using earlier tools based purely on reduction.

Enforcing Concurrent Temporal Behaviors

The outcome of verifying software is often a 'counterexample', i.e., a listing of the actions and states of a behavior not satisfying the specification. In order to understand the reason for the failure it is often required to test such an execution against the actual code. In this way we also find out whether we have a genuine error or a “false negative”. Due to nondeterminism in concurrent code, recovering an erroneous behavior on the actual program is not guaranteed even if no abstraction was made and we start the execution with the prescribed initial state. Testers are faced with a similar problem when they have to show that a suspicious scenario can actually be executed. Such a scenario may involve some intricate scheduling and thus be illusive to demonstrate. We describe here a program transformation that translates a program in such a way that it can be verified and then reverse transformed for testing a suspicious behavior. Since the transformation implies changes to the original code, we strive to minimize its effect on the original program.

Reduced endogenous control in alien hand syndrome: evidence from naturalistic action

Patients with alien hand (AH) syndrome from medial frontal lesions exhibit involuntary but seemingly purposeful contralesional upper limb movements. Two observations about AH patients have received little, if any, experimental confirmation. The first is that AH is triggered opportunistically by nearby objects. The second is that AH behaviors are increased in conditions of fatigue or anxiety, i.e. under reduced attentional control. A prominent account explains AH as reduced intention-driven (endogenous) executive control. This account predicts that erroneous AH behaviors should be driven by environmental (i.e. exogenous) factors, such as distractor proximity to the hand. AH errors should be less influenced by the intention or action plan (i.e. endogenous factors), such as the semantic relatedness of distractors to targets. Moreover, due to capacity limitations of the endogenous controller, AH behaviors should increase under conditions of secondary task load. We tested these predictions with an AH patient in two experiments using a naturalistic coffee-making task. Experiment 1 demonstrated that the affected hand was highly perseverative and strongly influenced by exogenous but not endogenous factors. The non-alien hand made fewer errors. Experiment 2 showed that there was a disproportionate increase in perseverations and exogenous errors of the affected hand under secondary task load. The non-alien hand was significantly less disrupted by dual task conditions. These data provide experimental support for previous anecdotal observations about AH behavior in naturalistic settings, and are consistent with a unilateral defect in endogenous control.

Toward CNN Chip-Specific Robustness

The promising potential of cellular neural networks (CNN) has resulted in the development of several template design methods. The CNN universal machine (CNN-UM), a programmable CNN, has made it possible to create image-processing algorithms that run on this platform. However, very large-scale integration implementations of CNN-UMs presented parameter deviations that do not occur on ideal CNN structures. Consequently, new design methods were developed aiming at more robust templates. Although these new templates were indeed more robust, erroneous behavior can still be observed. An alternative for chip-independent robustness is chip-specific optimization, where the template is targeted to an individual chip. This paper describes a solution proposal in this sense to automatically tune templates in order to make the chip react as an ideal CNN structure. The approach uses measurements of actual CNN-UM chips as part of the cost function for a global optimization method to find an optimal template given an initial approximation. Further improvements are achieved by generating chip-specific robust templates by doing a search for the best template among the optimal ones. The tuned templates are therefore customized versions that are expected to be much less sensitive to imperfections on the operation of CNN-UM chips. Results are presented for the binary and grayscale cases, including the case of grayscale output. It is expected that as this technique matures, it will give CNN-UM chips enough reliability to compete with digital systems in terms of robustness in addition to advantages of speed.

Full spectrum k-distribution correlations for CO 2 from the CDSD-1000 spectroscopic databank

Radiative heat transfer through molecular gases is a very important mode of energy transfer when dealing with combustion systems or modelling atmospheric processes. The most accurate radiative transfer results are obtained through line-by-line (LBL) calculations, which require, however, a prohibitively large computational effort. Consequently a number of global and band models have been proposed. Presently, the most accurate global models are the Full-Spectrum k-distributions (FSK) by Modest and coworkers [1, 2]. Earlier, somewhat less refined, related methods include the Spectral-Line-Based WeightedSum-of-Gray-Gases [3–5] or SLW and Absorption-Distribution-Function(ADF) [6, 7] models. All of these methods are orders-of-magnitude more efficient than LBL calculations, and they all use full-spectrum kdistributions, which, in general, need to be calculated from high-resolution databases, such as HITRAN [8], HITEMP [9] or —for CO2— the new CDSD-1000 [10, 11]. Both the SLW and ADF methods use simplified k-distributions reducing them to step-functions (gray gases), whereas the full-spectrum k-distribution method uses Gaussian quadrature to integrate over g-space resulting in better accuracy. Assembling such k-distributions is a rather tedious task and, therefore, to make simple engineering calculations feasible, Denison and Webb [12, 13] have proposed several simple full-spectrum k-distribution correlations for CO2 and H2O, based on the outdated HITRAN92 [8] database, combined with some extrapolations of their own for high temperatures. Recently, Zhang and Modest [14] provided an updated correlation for CO2 based on the newer HITEMP database which is purported to be accurate to at least 1000K. Unfortunately, it appears that the HITEMP database shows some erroneous behavior for temperatures beyond 1200K, as seen by comparison with experimental data [10,15]. The new CDSD-1000 databank [10,11], on the other hand, follows experimental data much more closely. Thus, it is the purpose of this note to provide a simple engineering correlation for full-spectrum k-distributions evaluated from the CDSD-1000 databank. ∗To whom all correspondence should be addressed. Fax: (814)863-8682; Email: mfm6@psu.edu

The design of reliable devices for mission-critical applications

Mission-critical applications require that any failure that may lead to erroneous behavior and computation is detected and signaled as soon as possible in order not to jeopardize the entire system. Totally self-checking (TSC) systems are designed to be able to autonomously detect faults when they occur during normal circuit operation. Based on the adopted TSC design strategy and the goal pursued during circuit realization (e.g., area minimization), the circuit, although TSC, may not promptly detect the fault depending on the actual number of input configurations that serve as test vectors for each fault in the network. If such a number is limited, although TSC it may be improbable that the fault is detected once it occurs, causing detection and aliasing problems. The paper presents a design methodology, based on a circuit re-design approach and an evaluation function, for improving a TSC circuit promptness in detecting faults' occurrence, a property we will refer to as TSC quality.

De-Fixating the Operator: Current Behavior Models Reviewed

Human controllers take a prominent place in the supervision and control of complex dynamic systems. Despite the achieved high safety standards there is a widespread acceptance that human error and thus erroneous behavior is inevitable in the end. Current efforts to cope with erroneous behavior are based on behavior models using a control perspective. Since these models cannot process erroneous behavior, an alternative perspective to model human behavior is proposed, namely autonomy. For autonomous living systems the critical variable is sense of influence.

Performing integrated system tests using malicious component insertion

In this paper, a testing method suitable for strengthening fault tolerance in the event of unexpected situations within a software system is presented. It is based on the idea of testing an integrated system, by substituting system components with other, similar in design and functionality that operate in an erroneous and even malicious manner. The approach adopted, is similar to the concept of inserting a virus within an organization so that the defense mechanisms of the latter can be tested and the necessary lines of defense are formed, so that the virus cannot affect any of the organization critical parts. The focal point is to ensure that in case of a module malfunction, the integrated system will continue to operate, isolating the malfunctioning software at the greatest possible extend, preventing the erroneous behavior from affecting other (and sometimes critical) modules. The testing method proposed is based first on isolated components testing adopting and enhancing the Component Off The Self method, and second on integrated system testing using malicious components that emulate erroneous operation.

Comparison of physical and software-implemented fault injection techniques

This paper addresses the issue of characterizing the respective impact of fault injection techniques. Three physical techniques and one software-implemented technique that have been used to assess the fault tolerance features of the MARS fault-tolerant distributed real-time system are compared and analyzed. After a short summary of the fault tolerance features of the MARS architecture and especially of the error detection mechanisms that were used to compare the erroneous behaviors induced by the fault injection techniques considered, we describe the common distributed testbed and test scenario implemented to perform a coherent set of fault injection campaigns. The main features of the four fault injection techniques considered are then briefly described and the results obtained are finally presented and discussed. Emphasis is put on the analysis of the specific impact and merit of each injection technique.

Instantaneous Measurement of Reflectance Spectra in the Open Field using Diode Array Spectrometers

A sensor and a calibration procedure for instantaneous measurements of reflectance spectra in the open field have been developed that eliminates the need for frequent irradiance reference recordings. The presented method for measuring reflectance was based on simultaneous irradiance and radiance recordings using two diode array spectrometers with separate upwards and downwards directed collimators. The wavelength range of the system was 360–900 nm. Formulae for calculating reflectance including radiometric calibration and correction for wavelength matching between the two spectrometer modules were developed. Measurements of reflectance spectra, made in manually thinned spring wheat, were consistent with results found in the literature. The developed formulae made it possible to adjust the utilisation of the range of measurement through altering the integration time. An iterative procedure for the automatic change of integration time ensured 90–100% utilisation of the range of measurement. No significant erroneous behaviour of the reflectance spectra could be found using the correction for wavelength matching between irradiance and radiance recordings. The system was found to be fast and no moving components were used. The developed formulae improved the procedure for measuring reflectance spectra by the ability of optimising the utilisation of the range of measurement.

Multi-Level Fault Injections in VHDL Descriptions: Alternative Approaches and Experiments

The probability of transient faults increases with the evolution of technologies. There is a corresponding increased demand for an early analysis of erroneous behaviours. This paper discusses alternative approaches to perform transient fault injection in circuits described in a high level language such as VHDL. In the proposed analysis flow, a behavioural model is generated, allowing the designer to identify the detailed error propagation paths in the circuit. This paper also reports on results obtained with SEU-like fault injections in VHDL descriptions of digital circuits. Several circuit description levels are considered, as well as several fault modelling levels. These results show that an analysis performed at a very early stage in the design process can actually give a helpful insight into the response of a circuit when a fault occurs.

Automated test case generation for the stress testing of multimedia systems

AbstractWith the advancement in network bandwidth and computing power, multimedia systems have become a popular means for information delivery. However, general principles of system testing cannot be directly applied to testing of multimedia systems on account of their stringent temporal and synchronization requirements. In particular, few studies have been made on the stress testing of multimedia systems with respect to their temporal requirements under resource saturation. Stress testing is important because erroneous behavior is most likely to occur under resource saturation. This paper presents an automatable method of test case generation for the stress testing of multimedia systems. It adapts constraint solving techniques to generate test cases that lead to potential resource saturation in a multimedia system. Coverage of the test cases is defined upon the reachability graph of a multimedia system. The proposed stress testing technique is supported by tools and has been successfully applied to a real‐life commercial multimedia system. Although our technique focuses on the stress testing of multimedia systems, the underlying issues and concepts are applicable to other types of real‐time systems. Copyright © 2002 John Wiley & Sons, Ltd.

On the applicability of the longest-match rule in lexical analysis

The lexical analyzer of a compiler usually adopts the longest-match rule to resolve ambiguities when deciding the next token in the input stream. However, that rule may not be applicable in all situations. Because the longest-match rule is widely used, a language designer or a compiler implementor frequently overlooks the subtle implications of the rule. The consequence is either a flawed language design or a deficient implementation. We propose a method that automatically checks the applicability of the longest-match rule and identifies precisely the situations in which that rule is not applicable. The method is useful to both language designers and compiler implementors. In particular, the method is indispensable to automatic generators of language translation systems since, without the method, the generated lexical analyzers can only blindly apply the longest-match rule and this results in erroneous behaviors. The crux of the method consists of two algorithms: one is to compute the regular set of the sequences of tokens produced by a nondeterministic Mealy automaton when the automaton processes elements of an input regular set. The other is to determine whether a regular set and a context-free language have nontrivial intersection with a set of equations.

Velocity analysis in the presence of amplitude variation

Conventional semblance velocity analysis is equivalent to modeling prestack seismic data with events that have hyperbolic moveout but no amplitude variation with offset (AVO). As a result of its assumption that amplitude is independent of offset, this method might be expected to perform poorly for events with strong AVO—especially for events with polarity reversals at large offset, such as reflections from tops of some class 1 and class 2 sands. We find that substantial amplitude variation and even phase change with offset do not compromise the conventional semblance measure greatly. Polarity reversal, however, causes conventional semblance to fail. The semblance method can be extended to take into account data with events that have amplitude variation, expressed by AVO intercept and gradient (i.e., the Shuey approximation). However, because of the extra degrees of freedom introduced in AVO‐sensitive semblance, resolution of the estimated velocities is decreased. This is because the data can be modeled acceptably with a range of combined erroneous velocity and AVO behavior. To address this problem, in addition to using the Shuey equation to describe the amplitude variation, we constrain the AVO parameters (intercept and gradient) to be related linearly within each semblance window. With this constraint we can preserve velocity resolution and improve the quality of velocity analysis in the presence of amplitude and even polarity variation with offset. Results from numerical tests suggest that the modified semblance is accurate in the presence of polarity reversals. Tests also indicate, however, that in the presence of noise, the signal peak in conventional semblance has better standout than does that in the modified semblance measures.

Trauma news today

Abnormal respiratory rates are one of the first indicators of clinical deterioration in emergency department(ED) patients. Despite the importance of respiratory rate observations, this vital sign is often inaccurately recorded on ED observation charts, compromising patient safety. Concurrently, there is a paucity of research reporting why this phenomenon occurs.To develop a substantive theory explaining ED registered nurses' reasoning when they miss or misreport respiratory rate observations.This research project employed a classic grounded theory analysis of qualitative data. Participants: Seventy-nine registered nurses currently working in EDs within Australia. Data collected included detailed responses from individual interviews and open-ended responses from an online questionnaire.Classic grounded theory (CGT) research methods were utilised, therefore coding was central to the abstraction of data and its reintegration as theory. Constant comparison synonymous with CGT methods were employed to code data. This approach facilitated the identification of the main concern of the participants and aided in the generation of theory explaining how the participants processed this issue.The main concern identified is that ED registered nurses do not believe that collecting an accurate respiratory rate for ALL patients at EVERY round of observations is a requirement, and yet organizational requirements often dictate that a value for the respiratory rate be included each time vital signs are collected. The theory ‘Rationalising Transgression’, explains how participants continually resolve this problem. The study found that despite feeling professionally conflicted, nurses often erroneously record respiratory rate observations, and then rationalise this behaviour by employing strategies that adjust the significance of the organisational requirement. These strategies include; Compensating, when nurses believe they are compensating for errant behaviour by enhancing the patient’s outcome; Minimalizing, when nurses believe that the patient’s outcome would be no different if they recorded an accurate respiratory rate or not and; Trivialising, a strategy that sanctions negligent behaviour and occurs when nurses ‘cut corners’ to get the job done. Nurses’ use these strategies to titrate the level ofemotional discomfort associated with erroneous behaviour, thereby rationalising transgressionThis research reveals that despite continuing education regarding gold standard guidelines for respiratory rate collection, suboptimal practice continues. Ideally, to combat this transgression, a culture shift must occur regarding nurses' understanding of acceptable practice methods. Nurses must receive education in a way that permeates their understanding of the relationship between the regular collection of accurate respiratory rate observations and optimal patient outcomes.

On dispersion force correction terms in perturbed equations of state

The first-order correction term for the contribution of dispersion forces in a perturbation expansion has been analyzed using computer simulation and perturbation theory results. It turns out that simple approximations used to make an analytic evaluation of the correction integral possible may result, ironically, in more complicated (and erroneous) behavior in comparison with the exact result.

Improved correlations for heavy n-paraffin physical properties

Critical properties and acentric factors are essential input parameters for equation-of-state models. Experimental data for such properties are limited for heavy hydrocarbons; this necessitates the use of property correlations based on data for lighter members of the homologous series under study. However, inaccurate estimates of the critical properties and the acentric factors often translate to erroneous phase behavior predictions and computational failures. Recent experimental measurements extend the available data on critical properties of n-paraffins up to n-C 36; using this information, we have examined a number of existing correlations for predicting n-paraffin physical properties. Careful evaluation of the quality and the extrapolation capability of each correlation indicates that the asymptotic behavior correlation (ABC) is well suited for the task. Accordingly, we have updated the ABC using the recent experimental data. The accuracy of the updated correlations for describing experimental critical temperature, critical pressure, acentric factor, critical compressibility, and normal boiling point temperature for normal paraffins is 0.2, 0.8, 0.4, 0.6, and 0.1%, respectively, over the range from C 3 to n-C 36.