Diagnosability of fair discrete event systems

Failure diagnosability has been widely studied using discrete event system (DES) models. It is, however, shown in this work by means of a counterexample that the diagnosability condition, which has been shown to be necessary and sufficient in the DES context, fails to hold for many real‐world hybrid systems. This is because the abstraction employed in formulating the DES models obliterates the continuous dynamics. In the present work, a new failure diagnosability mechanism has been developed for discrete time hybrid system (DTHS) models to alleviate this problem. A new diagnosability condition is proposed and its necessity and sufficiency with respect to the diagnosability definition are established formally. Finally, the method of A‐diagnosability, which can also be used to circumvent this problem and which needs additional probabilistic information for diagnosability analysis, has been shown to have a higher computational complexity than the DTHS model based method proposed in this paper. Further, it is also highlighted that the DTHS model based diagnosability analysis technique is capable of diagnosing faults that degrade the temporal performance of the system, which cannot be handled by the A‐diagnosability analysis mechanism. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Deterministic K-set structure

A k-set structure is a sub-linear space data structure that supports multi-set insertion and deletion operations and returns the multi-set, provided the number of distinct items with non-zero frequency does not exceed k. This is a fundamental problem with applications in data streaming [S. Muthukrishnan, Data streams: Algorithms and applications, Foundations and Trends in Theoretical Computer Science 1 (2) (2005)], distributed systems [Y. Minsky, A. Trachtenberg, R. Zippel, Set Reconciliation with Nearly Optimal Communication Complexity, IEEE Trans. Inform. Theory 49 (9) (2003) 2213-2218; D. Starobinski, A. Trachtenberg, S. Agarwal, Efficient PDA synchronization, IEEE Trans. on Mob. Comp. 2 (1) (2003) 40-51], etc. In this paper, we present the design of a deterministic k-set structure.     

A Numerical Simulation Model for Conjunctive Water Use in Basin Irrigated Canal Command Areas

Basin irrigation is a common practice for growing water intensive crops like paddy. Irrigation water, when supplied through a network of canal, is often found to be inadequate to meet the crop water requirement uniformly throughout the irrigated command area. The most deprived are the cultivators of the lower end of the command, who resort to supplementing the crop water requirement by extractions from the ground. This practice is noticeable in irrigation system without a proper canal water distribution schedule and often result in water logging in the upper command regions contrasted with excessively depleted groundwater table in the lower commands. The present contribution attempts to model the conjunctive water use of such a canal irrigated command using physically based numerical sub-models for simulating surface flow, groundwater flow and the interlinking process of moisture movement through the unsaturated zone for a given quantum of supplied water and crop water demand. Individual models are validated to demonstrate their applicability in an integrated framework. Various plausible conjunctive water use scenarios are tested on a hypothetical command area practising basin irrigation to identify the best possible water distribution strategy under given constraints.     

Appraising the Accuracy of Multi-Class Frequency Ratio and Weights of Evidence Method for Delineation of Regional Groundwater Potential Zones in Canal Command System

A comparative study of probabilistic frequency ratio (FR) and weights of evidence (WofE) method is performed for delineation of regional groundwater potential zones (GPZ) in canal command system. In the present case study, delineation of GPZ in the Hirakud agricultural command area of Odisha, India. Field discharge data from borewells are utilized for the analysis along with remote sensing (RS) and geographic information system (GIS) techniques. Various influencing attributes responsible for occurrence and movement of groundwater, e.g., land use / land cover, soil type, groundwater depth, geology, elevation, geomorphology, slope, recharge rate, rainfall, normalized difference vegetation index, drainage density, crop intensity are integrated by using GIS platform. Model results from FR and WofE show similar trends. The middle portion of the study area covers the ‘Good’ GPZ. Sensitivity analyses are performed for FR and WofE methods.     

Asynchronous Byzantine Agreement with optimal resilience

We present an efficient, optimally-resilient Asynchronous Byzantine Agreement (ABA) protocol involving $n = 3t+1$ parties over a completely asynchronous network, tolerating a computationally unbounded Byzantine adversary, capable of corrupting at most $t$ out of the $n$ parties. In comparison with the best known optimally-resilient ABA protocols of Canetti and Rabin (STOC 1993) and Abraham et al. (PODC 2008), our protocol is significantly more efficient in terms of the communication complexity. Our ABA protocol is built on a new statistical asynchronous verifiable secret sharing (AVSS) protocol with optimal resilience. Our AVSS protocol significantly improves the communication complexity of the only known statistical and optimally-resilient AVSS protocol of Canetti et al. Our AVSS protocol is further built on an asynchronous primitive called asynchronous weak commitment (AWC), while the AVSS of Canetti et al. is built on the primitive called asynchronous weak secret sharing (AWSS). We observe that AWC has weaker requirements than AWSS and hence it can be designed more efficiently than AWSS. The common coin primitive is one of the most important building blocks for the construction of an ABA protocol. In this paper, we extend the existing common coin protocol to make it compatible with our new AVSS protocol that shares multiple secrets simultaneously. As a byproduct, our new common coin protocol is more communication efficient than all the existing common coin protocols.     

Movement of bromide as a tracer for nitrate in an Alfisol of the Indian Semi-Arid Tropics under rainfed condition

The variable responses of crops to added nitrogen (N) in Alfisols of the Indian semi-arid tropics are partly due to variable rainfall and partly due to variable losses of available-N. To measure the losses of N through leaching, which can be appreciable under some circumstances, a field experiment was conducted during the rainy season (June-September) of 1992, using bromide (Br) as a tracer for NO ₃ ^- . Bromide (as NaBr) was applied to bare fallow soil at a rate of 200 kg ha^–1 in microplots (2 m × 2 m) and its vertical movement was monitored periodically. Data on rainfall and Br^– distribution in the soil profile on different dates of soil sampling clearly indicated that the movement of Br^– was strongly dependent on rainfall. During the first month (15 June-15 July) after Br^– application, with scattered and light rainfall about 90% of the added Br^– remained in the soil profile (0.6 m). After continuous heavy rainfall in early August more than 90% Br^– had moved beyond 0.6 m depth. This indicates a very high risk of NO ₃ ^- leaching in this soil, and it is unavoidable without special measures to protect the applied N.     

Partial Transmit Sequence Optimization Using Improved Harmony Search Algorithm for PAPR Reduction in OFDM

This paper considers the use of the Partial Transmit Sequence (PTS) technique to reduce the Peak‐to‐Average Power Ratio (PAPR) of an Orthogonal Frequency Division Multiplexing signal in wireless communication systems. Search complexity is very high in the traditional PTS scheme because it involves an extensive random search over all combinations of allowed phase vectors, and it increases exponentially with the number of phase vectors. In this paper, a suboptimal metaheuristic algorithm for phase optimization based on an improved harmony search (IHS) is applied to explore the optimal combination of phase vectors that provides improved performance compared with existing evolutionary algorithms such as the harmony search algorithm and firefly algorithm. IHS enhances the accuracy and convergence rate of the conventional algorithms with very few parameters to adjust. Simulation results show that an improved harmony search‐based PTS algorithm can achieve a significant reduction in PAPR using a simple network structure compared with conventional algorithms.     

Mechanism of Error‐Free Bypass of the Environmental Carcinogen N‐(2′‐Deoxyguanosin‐8‐yl)‐3‐aminobenzanthrone Adduct by Human DNA Polymerase η

The environmental pollutant 3‐nitrobenzanthrone produces bulky aminobenzanthrone (ABA) DNA adducts with both guanine and adenine nucleobases. A major product occurs at the C8 position of guanine (C8‐dG‐ABA). These adducts present a strong block to replicative polymerases but, remarkably, can be bypassed in a largely error‐free manner by the human Y‐family polymerase η (hPol η). Here, we report the crystal structure of a ternary Pol?DNA?dCTP complex between a C8‐dG‐ABA‐containing template:primer duplex and hPol η. The complex was captured at the insertion stage and provides crucial insight into the mechanism of error‐free bypass of this bulky lesion. Specifically, bypass involves accommodation of the ABA moiety inside a hydrophobic cleft to the side of the enzyme active site and formation of an intra‐nucleotide hydrogen bond between the phosphate and ABA amino moiety, allowing the adducted guanine to form a standard Watson–Crick pair with the incoming dCTP.     

Multistability in Bistable Ferroelectric Materials toward Adaptive Applications

Traditionally thermodynamically bistable ferroic materials are used for nonvolatile operations based on logic gates (e.g., in the form of field effect transistors). But, this inherent bistability in these class of materials limits their applicability for adaptive operations. Emulating biological synapses in real materials necessitates gradual tuning of resistance in a nonvolatile manner. Even though in recent years few observations have been made of adaptive devices using a ferroelectric, the principal question as to how to make a ferroelectric adaptive has remained elusive in the literature. Here, it is shown that by locally controlling the nucleation energy distribution at the ferroelectric–electrode interface multiple‐addressable states in a ferroelectric can be created, which is necessary for adaptive/synaptic applications. This is realized by depositing a layer of nonswitchable ZnO on top of thin film ferroelectric PbZr _x Ti_{(1– x )}O₃. This methodology of interface‐engineered ferroelectric should enable realising brain‐like adaptive/synaptic memory in complementary metal‐oxide‐semiconductor (CMOS) devices. Furthermore, the temporally stable multistability in ferroelectrics should enable the designing of multistate memory and logic devices.     

The development of critical criteria to improve the alarm system in the process industry

The process industry handles most of the flammable and toxic materials within the industrial sector. Hence, safety issues are of prime importance as any possible accident can have severe consequences for both humans and the environment. For the safe and efficient operation of a plant while preventing mishaps in the process, a good alarm system is very important. Ultimate plant safety relies not only on the efficiency of the alarm system but also on the ability of the operators. In this study the authors develop the specifications required for a critical alarm system appropriate for most of the process industries; the specifications are based on optimal information flow between the operating system, guidance system, and the operator, ultimately to make the job less stressful and easier for the operators. The aim is to reduce the risk involved in control room operations that are associated with human factors. © 2006 Wiley Periodicals, Inc. Hum Factors Man 16: 321–337, 2006.