Counting Paths in VPA Is Complete for #NC 1

We give a #NC ¹ upper bound for the problem of counting accepting paths in any fixed visibly pushdown automaton. Our algorithm involves a non-trivial adaptation of the arithmetic formula evaluation algorithm of Buss, Cook, Gupta and Ramachandran (SIAM J. Comput. 21:755?C780, 1992). We also show that the problem is #NC ¹ hard. Our results show that the difference between #BWBP and #NC ¹ is captured exactly by the addition of a visible stack to a nondeterministic finite-state automaton.     

Continuous‐discrete filters for bearings‐only underwater target tracking problems

In this work, we develop a continuous‐discrete shifted Rayleigh filter (CD‐SRF) and a continuous‐discrete sparse‐grid Gauss‐Hermite filter (CD‐SGHF) for a real‐life passive underwater bearings‐only target tracking problem. The stochastic difference equation describing the process model is derived from its continuous equivalent using Ito‐Taylor expansion of order 1.5. The performance of the proposed filters is compared in terms of root mean square error (RMSE), track divergence and computational time. For a fair comparison, popular filters like the unscented Kalman filter (UKF), cubature Kalman filter (CKF) and Gauss–Hermite filter (GHF) are implemented. The effect of initial uncertainty, measurement noise covariance and sampling time on filtering accuracy is also studied. Finally, RMSEs of all the filters are evaluated in comparison with the Cramer–Rao lower bound (CRLB). From simulation results, it was observed that CD filters performed with higher accuracy than their discrete equivalents, with CD‐SRF proving to be the most accurate among all the filters.     

Analysis of reinforced concrete coupled shear wall structures

The ultimate strength analysis of reinforced concrete coupled shear walls with one or two bands of openings requires a two‐stage approach. In the first stage, the analysis of the coupling beams is carried out. This is followed by the analysis of the complete wall in the second stage. A simple approach based on the ‘total moment concept’ for the analysis of coupled shear walls with one or two bands of openings is presented. Experimental results supporting the predictions of the mode of failure and ultimate strength is also presented. This study updates previous research and enhances further understanding of the behaviour of reinforced concrete shear wall structures at ultimate limit states of loading. Copyright © 1999 John Wiley & Sons, Ltd.     

Robust design of flexible manufacturing systems using, colored Petri net and genetic algorithm

A method is presented for the robust design of flexible manufacturing systems (FMS) that undergo the forecasted product plan variations. The resource allocation and the operation schedule of a FMS are modeled as a colored Petri net and an associated transition firing sequence. The robust design of the colored Petri net model is formulated as a multi-objective optimization problem that simultaneously minimizes the production costs under multiple production plans (batch sizes for all jobs), and the reconfiguration cost due to production plan changes. A genetic algorithm, coupled with the shortest imminent operation time (SIO) dispatching rule, is used to simultaneously find the near-optimal resource allocation and the event-driven schedule of a colored Petri net. The resulting Petri net is then compared with the Petri nets optimized for a particular production plan in order to address the effectiveness of the robustness optimization. The simulation results suggest that the proposed robustness optimization scheme should be considered when the products are moderately different in their job specifications so that optimizing for a particular production plan creates inevitably bottlenecks in product flow and/or deadlock under other production plans.     

Comparison of Listeria monocytogenes virulence in a mouse model

Listeriosis results from exposure to the foodborne pathogen Listeria monocytogenes. Although many different strains of L. monocytogenes are isolated from food, no definitive tests currently predict which isolates are most virulent. The objectives of this study were to address two major data gaps for risk assessors, variability among L. monocytogenes strains in pathogenicity and virulence. Strains used in our monkey clinical trial or additional food isolates were evaluated for their virulence and infectivity in mice. All strains were equally pathogenic to immunocompromised mice, causing deaths to 50% of the population 3 days after exposure to doses ranging from 2 to 3 log CFU. Doses resulting in 50% deaths on the fifth day after administration were 1 to 2 log lower than those on the third day, indicating that the full course of pathogenicity exceeds the 3-day endpoint in immunocompromised mice. Three strains were chosen for further testing for their virulence and infectivity in liver and spleen in normal (immunocompetent) mice. Virulence was not significantly different (P > 0.05) among the three strains, all resulting in deaths to 50% of mice at 5 to 7 log CFU by 5 days after administration. All strains were equally infective in liver or spleen, with higher numbers of L. monocytogenes directly correlated with higher doses of administration. In addition, there was no preference of organs by any strains. The lack of strain differences may reflect the limitation of the mouse model and suggests the importance of using various models to evaluate the pathogenicity and virulence of L. monocytogenes strains.     

A cooking quality parameter as an indicator of adulteration of Basmati rice

Among various cooking quality parameters, differential length/breadth ratio has been found to be a reliable indicator of adulteration of Basmati rice, with Improved Sabarmati, Pusa-169, PR-106, Kali-much, Lakra and Parimal, which are the rice varieties used frequently for adulteration. A minimum value of length/breadth ratio of 3.92±0.09 to 4.09±0.09 was found to be indicative of pure Basmati.     

Colloidal lead-free Cs2AgBiBr6double perovskite nanocrystals:Synthesis,uniform thin-film fabrication,and application in solution-processed solar cells

Recently developed lead-free double perovskite nanocrystals(NCs)have been proposed for the possible application in solutionprocessed optoelectronic devices.However,the optoelectronic applications of double perovskite NCs have been hampered due to the structural and chemical instability in the presence of polar molecules.Here,we report a facile strategy for the synthesis and purification of Cs₂AgBiBr₆double perovskite NCs that remained stable even after washing with polar solvent.This is realized with our efficient colloidal route to synthesize Cs₂AgBiBr₆NCs that involve stable and strongly coordinated precursor such as silvertrioctyl phosphine complex together with bismuth neodecanoate,which leads to a significantly improved chemical and colloidal stability.Using layer-by-layer solid-state ligand exchange technique,a compact and crack-free thin film of Cs₂AgBiBr₆NCs were fabricated.Finally,perovskite solar cells consisting of Cs₂AgBiBr₆as an absorber layer were fabricated and tested.     

Upper Bounds for Monotone Planar Circuit Value and Variants

The P-complete Circuit Value Problem CVP, when restricted to monotone planar circuits MPCVP, is known to be in NC³, and for the special case of upward stratified circuits, it is known to be in LogDCFL. In this paper we re-examine the complexity of MPCVP, with special attention to circuits with cylindrical embeddings. We characterize cylindricality, which is stronger than planarity but strictly generalizes upward planarity, and make the characterization partially constructive. We use this construction, and four key reduction lemmas, to obtain several improvements. We show that stratified cylindrical monotone circuits can be evaluated in LogDCFL, and arbitrary cylindrical monotone circuits can be evaluated in AC¹(LogDCFL), while monotone circuits with one-input-face planar embeddings can be evaluated in LogCFL. For monotone circuits with focused embeddings, we show an upper bound of AC¹(LogDCFL). We re-examine the NC³ algorithm for general MPCVP, and note that it is in AC¹(LogCFL) = SAC². Finally, we consider extensions beyond MPCVP. We show that monotone circuits with toroidal embeddings can, given such an embedding, be evaluated in NC. Also, special kinds of arbitrary genus circuits can also be evaluated in NC. We also show that planar non-monotone circuits with polylogarithmic negation-height can be evaluated in NC.     

Preliminary observations on cooking quality parameters as indicators of adulteration of basmati rice

Differential length-breadth ratio and loss of solids in cooking water have been found to be reliable indicators of adulteration of Basmati rice with Saket-4 rice, which is one of the rice varieties used frequently for adulteration.