15363008
Word-voter: a new voter design for triple modular redundant systems
Redundancy techniques are commonly used to design dependable systems to ensure high reliability, availability and data integrity. Triple Modular Redundancy (TMR) is a widely used redundancy technique that masks faults. In a TMR system, we have three implementations of the same logic function and their outputs are voted using a voter circuit. In this paper, we present a new voter design called the Word-Voter that has some distinct advantages over the bit-by-bit voting schemes used in conventional TMR systems. This paper demonstrates the usefulness of the word-voter design in increasing the data integrity (reducing the probability of corrupt outputs) of TMR systems. The area and delay overhead of the word-voter design is compared to that of the bit-by-bit voter. An efficient design of a TMR-Simplex system using the word-voter is also presented.
2705949
Logic soft errors in sub-65nm technologies design and CAD challenges
Logic soft errors are radiation induced transient errors in sequential elements (flip-flops and latches) and combinational logic. Robust enterprise platforms in sub-65nm technologies require designs with built-in logic soft error protection. Effective logic soft error protection requires solutions to the following three problems: (1) accurate soft error rate estimation for combinational logic networks; (2) automated estimation of system effects of logic soft errors, and identification of regions in a design that must be protected; and, (3) new cost-effective techniques for logic soft error protection, because classical fault-tolerance techniques are very expensive.
2734062
A design diversity metric and reliability analysis for redundant systems
Design diversity has long been used to protect redundant systems against common-mode failures. The conventional notion of diversity relies on "independent" generation of "different" implementations. This concept is qualitative and does not provide a basis to compare the reliabilities of two diverse systems. In this paper, for the first time, we present a metric to quantify diversity among several designs. Based on this metric, we derive analytical reliability models that show a simple relationship between design diversity, system failure rate, and mission time. In addition, we present simulation results to demonstrate the effectiveness of design diversity in Duplex and Triple Modular Redundant (TMR) systems. For independent multiple-module failures, we show that, mere use of different implementations does not always guarantee higher reliability compared to redundant systems with identical implementations-it is important to analyze the reliability of redundant systems using our metric. For common-mode failures and design faults, there is a significant gain in using different implementations-however, as our analysis shows, the gain diminishes as the mission time increases. Our simulation results also demonstrate the usefulness of diversity for enhancing the self-testing properties of redundant systems.
900289
Techniques and algorithms for fault grading of FPGA interconnect test configurations
Conventional fault simulation techniques for field programmable gate arrays (FPGAs) are very complicated and time consuming. The alternative, FPGA fault emulation technique, is incomplete and can be used only after the FPGA chip is manufactured. In this paper, we present efficient algorithms for computing the fault coverage of a given FPGA test configuration. The faults considered are opens and shorts in FPGA interconnects. The presented technique is able to report all detectable and undetectable faults and, compared with conventional methods, is orders of magnitude faster.
2397835
Speed clustering of integrated circuits
Experimental data on 0.18 /spl mu/ test chips shows strong evidence of clustering of speeds of neighboring dies on a wafer. This clustering phenomenon is utilized to develop techniques for predicting the speed of a part from the speeds of three or more of its neighbors. On-chip processor monitors are used to further improve the prediction accuracy of these techniques. Experimental data demonstrates both the effectiveness of these prediction schemes and the possibility of applying of them to reduce the cost of speed binning.
18607273
X-tolerant test response compaction
Larger, denser designs lead to more defects; higher quality requirements and new test methods lead to an explosion in test data volume. Test compression technique attempt to do more testing with fewer bits. This article summarizes one such method, X compact which addresses how unknowns the bane of compression and logic BIST techniques are eliminated. DFT engineers must spend serious effort to minimize Xs in future designs. It is impossible to eliminate all Xs. X-tolerant response compactors are necessary for tolerating residual Xs to enable massive compaction with practically no impact on test quality. X-compactors are mainly useful for test compression purposes and provide up to 80 times the test response compaction of traditional scan. X-tolerant signature analyzers extend the X-compact concept to incorporate time compaction, thereby tolerating thousands of Xs and reducing test response data volume by 50 to 2,000 times relative to traditional scan. These signature analyzers are extremely beneficial for BIST because Xs can easily corrupt traditional MISR-based BIST signature analyzers. X-tolerant response compactors also enable efficient diagnosis essential to fast yield-learning.
29308229
Safety Verification of Model Helicopter Controller Using Hybrid Input/Output Automata
This paper presents an application of the Hybrid I/O Automaton (HIOA) framework [12] in verifying a realistic hybrid system. A supervisory pitch controller for a model helicopter system is designed and then verified. The design of the supervisor is limited by the actuator bandwidth, the sensor inaccuracies, and the sampling rates. Verification is carried out by induction over the length of an execution of the composed system automaton. The HIOA model makes the inductive proofs tractable by decomposing them into independent discrete and continuous parts. The paper also presents a set of language constructs for specifying hybrid I/O automata.
15125333
Evolutionary modular design of rough knowledge-based network using fuzzy attributes
This article describes a way of integrating rough set theory with a fuzzy MLP using a modular evolutionary algorithm, for classification and rule generation in soft computing paradigm. The novelty of the method lies in applying rough set theory for extracting dependency rules directly from a real-valued attribute table consisting of fuzzy membership values. This helps in preserving all the class representative points in the dependency rules by adaptively applying a threshold that automatically takes care of the shape of membership functions. An l-class classification problem is split into l two-class problems. Crude subnetwork modules are initially encoded from the dependency rules. These subnetworks are then combined and the final network is evolved using a GA with restricted mutation operator which utilizes the knowledge of the modular structure already generated, for faster convergence. The GA tunes the fuzzification parameters, and network weight and structure simultaneously, by optimising a single fitness function. This methodology helps in imposing a structure on the weights, which results in a network more suitable for rule generation. Performance of the algorithm is compared with related techniques.
62742629
Local facial asymmetry for expression classification
We explore a novel application of facial asymmetry: expression classification. Using 2D facial expression images, we show the effectiveness of automatically selected local facial asymmetry for expression recognition. Quantitative evaluations of expression classification using local asymmetry demonstrate statistically significant improvements over expression classification results on the same data set without explicit representation of facial asymmetry. A comparison of discriminative local facial asymmetry features for expression classification versus human identification is given.
45280262
Leveraging information in multi-echelon inventory systems
Abstract Decision-making in multi-echelon inventory systems is often facilitated by the availability of information. In this paper, we examine the effect of utilising demand information in a one-warehouse two-retailer system operating under periodic-review. A common and fixed replenishment interval is assumed for all stages. The lead times are deterministic, and are small compared to the replenishment interval. The warehouse does not maintain any cycle stock, i.e., as soon as replenishment arrives at the warehouse, retailers’ demands are fulfilled from the available stock. In the event of a shortage at the warehouse, two cases have been considered––emergency shipment and allocation. For both the cases, expected total cost (ETC) models have been developed, and it has been shown through numerical examples that the optimal ETC in the presence of demand information is always lower than that in the absence of demand information. It is also noted that the order-up-to level at the warehouse has to be dynamic to reap the benefits of availability of demand information.
13253511
Verifying Average Dwell Time by Solving Optimization Problems
A switched system is a hybrid system whose discrete mechanisms are abstracted away in terms of an exogenous switching signal which brings about the mode switches. For switched systems, the Average Dwell time (ADT) property defines restricted classes of switching signals which can be used for proving stability. In this paper, we develop optimization-based methods for automatically verifying ADT properties of hybrid systems. This enables us to prove stability of hybrid systems, provided the individual modes of the system are stable. For two special classes of hybrid systems, we show that the resulting optimization problems can indeed be solved efficiently using standard mathematical programming techniques. We also present simulation relation-based proof methods for establishing equivalence of hybrid systems with respect to ADT. The proposed methods are applied to verify ADT properties of a linear hysteresis switch and a nondeterministic thermostat.