Terms Of Testability Research Articles

Model evaluation in human factors and ergonomics (HFE) sciences; case of trust in automation

Theories and models are central to Human Factors/Ergonomics (HFE) sciences for producing new knowledge, pushing the boundaries of the field, and providing a basis for designing systems that can improve human performance. Despite the key role, there has been less attention to what constitutes a good theory/model and how to examine the relative worth of different theories/models. This study aims to bridge this gap by (1) proposing a set of criteria for evaluating models in HFE, (2) employing a methodological approach to utilize the proposed criteria, and (3) evaluating the existing models of trust in automation (TiA) according to the proposed criteria. The resulting work provides a reference guide for researchers to examine the existing models’ performance and to make meaningful comparisons between TiA models. The results also shed light on the differences among TiA models in satisfying the criteria. While conceptual models offer valuable insights into identifying the causal factors, their limitation in operationalization poses a major challenge in terms of testability and empirical validity. On the other hand, although more readily testable and possessing higher predictive power, computational models are confined to capturing only partial causal factors and have reduced explanatory power capacity. The study concludes with recommendations that in order to advance as a scientific discipline, HFE should adopt modelling approaches that can help us understand the complexities of human performance in dynamic sociotechnical systems.

Automated measurement of resolution acuity in infants using remote eye-tracking.

To validate a novel, automated test of infant resolution acuity based on remote eye-tracking. Infants aged 2 to 12 months were tested binocularly using a new adaptive computerized test of infant vision using eye tracking (ACTIVE), and Keeler infant acuity cards (KIAC). The ACTIVE test ran automatically, using remote eye-tracking to assess whether the infant fixated a black-and-white grating of variable spatial frequency. Test-retest reliability was assessed by performing each test twice. Accuracy was assessed by comparing acuity measures across tests and with established age-norms, and by comparing low-contrast acuity estimates in adults with data reported previously. All infants completed the ACTIVE test at least once. Median test duration was 101 seconds. Measured visual acuity increased with age (P < 0.001), and 90% of mean acuity estimates were within previously published 90% tolerance limits (based on acuity-card age norms). Acuity estimates were also correlated, within-subjects, with results from the KIAC (P = 0.004). In terms of reliability, 86% of acuity estimates deviated by ≤1 octave, with no significant difference in test-retest reliability between the ACTIVE and KIAC procedures (P = 0.461). In adults, acuity estimates from the ACTIVE test did not differ significantly from values reported by previous authors (P > 0.183). An adaptive computerized test of infant vision using eye-tracking provides a rapid, automated measure of resolution acuity in preverbal infants. The ACTIVE performed comparably to the current clinical gold standard (acuity cards) in terms of testability, reliability, and accuracy, and its principles can be extended to measure other visual functions.

Design of Testable Reversible Memory Circuits

Quantum dot Cellular Automata (QCA) is the new possibility for the future of nano-electronic computing technology which employs the principle of quantum mechanics. This paper, contributes to the design of Memory circuits based on conservative reversible logic gates & also the design is made testable using two test vectors. The conservative logic gates dominates the classical gates in terms of testability, feature size scaling & high power consumption for the design of sequential circuits. Here the Memory circuits (1-bit, 4-bit & 8-bit) are designed by employing conservative logic gates(Fredkin Gate), which is being simulated and tested for the detection of unidirectional stuck-at faults using two test vectors 0s & 1s. For the simulation of the described designs Xilinx's 8.2 EDA tool is used.

Design of Testable Reversible Sequential Circuits

In this paper, we propose the design of two vectors testable sequential circuits based on conservative logic gates. The proposed sequential circuits based on conservative logic gates outperform the sequential circuits implemented in classical gates in terms of testability. Any sequential circuit based on conservative logic gates can be tested for classical unidirectional stuck-at faults using only two test vectors. The two test vectors are all 1's, and all 0's. The designs of two vectors testable latches, master-slave flip-flops and double edge triggered (DET) flip-flops are presented. The importance of the proposed work lies in the fact that it provides the design of reversible sequential circuits completely testable for any stuck-at fault by only two test vectors, thereby eliminating the need for any type of scan-path access to internal memory cells. The reversible design of the DET flip-flop is proposed for the first time in the literature. We also showed the application of the proposed approach toward 100% fault coverage for single missing/additional cell defect in the quantum-dot cellular automata (QCA) layout of the Fredkin gate. We are also presenting a new conservative logic gate called multiplexer conservative QCA gate (MX-cqca) that is not reversible in nature but has similar properties as the Fredkin gate of working as 2:1 multiplexer. The proposed MX-cqca gate surpasses the Fredkin gate in terms of complexity (the number of majority voters), speed, and area.

A TOOL TO AUTOMATICALLY MAP IMPLEMENTATION-BASED TESTING TECHNIQUES TO CLASSES

The object-oriented (OO) paradigm provides several benefits during analysis and design of large-scale software systems, but scores lower in terms of testability. The low testability score for OO software is due mainly to the composition of OO systems exhibiting the characteristics of abstraction, encapsulation, genericity, inheritance, polymorphism, concurrency and exception handling. To address the difficulty of testing the features of a class, a plethora of implementation-based testing techniques (IBTTs) have been developed. However, no one IBTT has emerged as the preferred technique to test the implementation of a class. In this paper we present a technique that automatically identify those IBTTs that are most suitable for testing a class based on the characteristics of that class. Our approach uses a taxonomy of OO classes that is used to succinctly abstract the characteristics of a class under test (CUT). We have implemented a tool that automates the process of mapping IBTTs to a class. In addition to identifying the IBTTs that would be best suited for testing a class, our tool provides feedback to the tester facilitating the identification of the characteristics of the class that are not suitably tested by any of the IBTTs in the list. We provide results of a study supporting the notion that using more than on IBTT during testing improves test coverage of a CUT.

A new classification of path-delay fault testability in terms of stuck-at faults

A new classification of path-delay fault testability in a combinational circuit is presented in terms of testability of stuck-at faults in an equivalent circuit. Earlier results describing correlation of path-delay and stuck-at faults are either incomplete, or use a complex model of equivalent circuit based on timing parameters. It is shown here that a path-delay fault (rising or falling) is testable if and only if certain single or multiple stuck-at fault in the equivalent circuit is testable. Thus, all aspects of path-delay faults related to testability under various classification schemes can be interpreted using the stuck-at fault model alone. The results unify most of the existing concepts and provide a better understanding of path-delay faults in logic circuits.

Easily Testable Cellular Carry Lookahead Adders

Cellular Carry Lookahead (CLA) adders are systematically implemented in arithmetic units due to their regular, well-balanced structure. In terms of testability and with respect to the classical Cell Fault Model (CFM), cellular CLA adders have poor testability by construction. Design-for-testability (DFT) modifications for cellular CLA adders have been proposed in the literature providing complete CFM testability making the adders either level-testable or C-testable. These designs impose significant area and performance overheads. In this paper, we propose DFT modifications for cellular CLA adders to achieve complete CFM testability with special emphasis on the minimum impact in terms of area and performance. Complete CFM testability is achieved without adding any extra inputs to the adder, with very small area and performance overheads, thus providing a practical solution. The proposed DFT scheme requires only 1 extra output and it is not necessary to put the circuit in a special test mode, while the earlier schemes require the addition of 2 extra inputs to set the circuit in test mode. A rigorous proof of the linear-testability of the adder is given and a sufficient linear-sized test set is provided that guarantees 100% CFM fault coverage. Surprisingly, the size of the proposed linear-sized test set is, in most practical cases, comparable or even smaller than a logarithmic-sized test set proposed in the literature.

Training fuzzy logic based software components by combining adaptation algorithms

A training framework of an effective method for off-line training of a class of control software components (e.g., for first-order nonlinear feedback control systems) using combinations of three kinds of adaptation algorithms is presented. Each control software component is represented at the abstract level by means of a set of adaptive fuzzy logic (FL) rules and at the concrete level by means of fuzzy membership functions (MBFs). At the concrete representation level adaptation algorithms specified for use in adapting MBFs are: genetic algorithms, neural net algorithms, and Monte Carlo algorithms. We specify effective combinations of these three existing adaptation algorithms to train a faulty FL rule-based software component for the tracker problem. In the framework, training consists of two phases: testing and adapting. In the testing phase, a test driver generates an effective fault scenario ( fs) and locates the faulty fuzzy elements (FFEs) by using each or a combination of three adaptation algorithms. In the adapting phase, for each fault scenario adaptation algorithms and their combinations are used to modify the MBFs of the component. Effectiveness of the two phase training is determined in terms of testability, flexibility, adaptability, and stability. An initial design of the simulation environment is presented. In the experiment, for a given circumstance (environment and fuzzy rules) we apply a combination of a genetic algorithm GA) and a neural network (NN) with an error back-propagation algorithm (BP) in the testing phase for generating fault scenarios. Then we apply GA-only method in the adapting phase for adapting the faulty software component. Simulation results on effectiveness and efficiency are discussed.

Testability and the Refutation and Corroboration of Cladistic Hypotheses

Both refutationist and verificationist philosophies and practices are becoming increasingly evident in phylogenetic inference. Refutation and verification are fundamentally different epistemologies, and it seems unlikely that they can continue to coexist as the basis for inferring species history. The refutationist nature of cladistics is explored in terms of Popperian testability, in order to understand better the alternatives and to predict the outcome of the expected revolution. Testability concerns the logical relationship between a hypothesis (h, such as a cladogram), evidence (e, such as synapomorphy), and background knowledge (b). Of particular importance is the direct relationship between the logical improbability ofhand its potential to be tested, because foreto corroborateh,eshould be improbable givenbalone. Simplicity and boldness, amount of empirical content, and logical improbability all refer to the potential to be tested. Thathmust be testable by severe tests is the same as saying that those tests have greater probability of failing, given onlyb. Descent with modification is sufficient as background knowledge (b) in phylogenetic inference, and such a minimal assumption explains the generality of cladistics. Also of interest to the refutationist position is total evidence. In terms of testability, a statement describing the results of multiple tests is less probable than a statement describing only some of the tests, the multiple test result being more improbable, and accordingly more severe, than its component tests. All other cladistic principles and practices considered in this review are also understandable in terms of Popperian testability, refutation and corroboration. These include minimizing ad hoc hypotheses of homoplasy and minimizing explanatory power, and choosing tentatively among cladograms according to their degree of corroboration (support). Differential character weighting is determined to be unacceptable in terms of testability. Also, testability does not provide a basis for assessing the accuracy of hypotheses, but then that is of no consequence to cladists, because they are not preoccupied with knowing the absolute truth, unlike verificationists.

Testability and the Refutation and Corroboration of Cladistic Hypotheses.

Both refutationist and verificationist philosophies and practices are becoming increasingly evident in phylogenetic inference. Refutation and verification are fundamentally different epistemologies, and it seems unlikely that they can continue to coexist as the basis for inferring species history. The refutationist nature of cladistics is explored in terms of Popperian testability, in order to understand better the alternatives and to predict the outcome of the expected revolution. Testability concerns the logical relationship between a hypothesis (h, such as a cladogram), evidence (e, such as synapomorphy), and background knowledge (b). Of particular importance is the direct relationship between the logical improbability ofhand its potential to be tested, because foreto corroborateh,eshould be improbable givenbalone. Simplicity and boldness, amount of empirical content, and logical improbability all refer to the potential to be tested. Thathmust be testable by severe tests is the same as saying that those tests have greater probability of failing, given onlyb. Descent with modification is sufficient as background knowledge (b) in phylogenetic inference, and such a minimal assumption explains the generality of cladistics. Also of interest to the refutationist position is total evidence. In terms of testability, a statement describing the results of multiple tests is less probable than a statement describing only some of the tests, the multiple test result being more improbable, and accordingly more severe, than its component tests. All other cladistic principles and practices considered in this review are also understandable in terms of Popperian testability, refutation and corroboration. These include minimizing ad hoc hypotheses of homoplasy and minimizing explanatory power, and choosing tentatively among cladograms according to their degree of corroboration (support). Differential character weighting is determined to be unacceptable in terms of testability. Also, testability does not provide a basis for assessing the accuracy of hypotheses, but then that is of no consequence to cladists, because they are not preoccupied with knowing the absolute truth, unlike verificationists.

Multilevel logic synthesis technique for efficient verification testing

To improve the verification testability of multilevel circuits, a multilevel logic synthesis technique, called VETERAN, for verification testability has been developed. The main steps in VETERAN are first, the determination of the minimum sets of input variables (referred to as 'minimum variable supports') for each output function. Secondly, an efficient verification testing scheme is derived from each set of input variable supports. Thirdly, the minimum variable support and the proper logic (uncomplementary or complementary logic) for every output are determined. Finally, a multilevel circuit, which can be tested by the previously determined verification testing scheme, is implemented by the conventional multilevel logic synthesis techniques. To prove the effectiveness of the proposed technique, it was compared with misII for 59 examples. In all 59 examples, the proposed technique gives results which are better than, or as good, as misII, in terms of testability. For 21 examples, the proposed technique results in smaller circuits, which have a better testability or the same testability.

Detection of stuck-at and bridging faults in reed—muller canonical (RMC) networks

Boolean function realisations by Reed—Muller networks have many desirable properties in terms of testability [11]. In the paper it is shown that there exists a single set of test patterns which would detect all single stuck-at and all single bridging (short-circuit) faults in Reed-Muller networks, and the number of test patterns is shown to be at most 3n + 5, where n is the number of input variables in the function. In the case of networks with k outputs, where k ≤ 2n, the number of test patterns required to detect all single stuck-at and all single detectable bridging faults (both AND and OR) is also shown to be 3n + 5.