Lexical state analyzer for JavaCC grammars

Lexical states in JavaCC provide a powerful mechanism to scan regular expressions in a context sensitive manner. But lexical states also make it hard to reason about the correctness of the grammar. We first categorize the related correctness issues into two classes: errors and warnings. We then extend the traditional context sensitive and a context insensitive analysis to identify errors and warnings in context‐free grammars. We have implemented these analyses as a standalone tool (LSA ), the first of its kind, to identify errors and warnings in JavaCC grammars. The LSA tool outputs a graph that depicts the grammar and the error transitions. Importantly, it can also generate counter example strings that can be used to establish the errors. We have used LSA to analyze a host of open‐source JavaCC grammar files to good effect. Copyright © 2015 John Wiley & Sons, Ltd.     

Compensating UAV GPS data accuracy through use of relative positioning and GPS data of UGV

Journal of Mechanical Science and Technology - We improve the performance of a low-quality GPS data on a UGV through use of multiple low-quality GPS modules on a UGV within line of sight of the...     

Revolutionizing supply chain management the theory of constraints way: a case study

This research describes in detail an application of theory of constraints (TOC) and its resulting benefits on the supply chain performance of India's largest lock manufacturing company over a period of seven years. Using TOC's thinking process, the core constraints that had limited the company's performance in the areas of production, distribution, supply group and projects were identified and eliminated. TOC's unique approach helped the company achieve a significant reduction in its finished goods, raw material and work-in-process inventories at various levels across the supply chain. The stock-outs and excess in the distribution system nearly disappeared. The existing lead times saw a drastic reduction while the availability of items increased to nearly 100% despite significant decrease in inventory levels in the supply chain. The inventory turns of the distributors and retailers more than tripled and their profitability increased significantly. The overall sales of the company grew nearly three times during the six years post TOC implementation. TOC's holistic approach helped the company to double its profits and improve its cash position during the Great Recession.     

Tensile behaviour of boron modified Timetal 834 titanium alloy in the intermediate temperature range 400-500 °C

The tensile behaviour of boron modified Timetal 834 titanium alloy was studied in the intermediate temperature range 400-500 °C and compared with that of the base alloy. The yield and ultimate tensile strengths of the B modified alloy were found to be higher than those of the base alloy at all the temperatures investigated. The B modified alloy also exhibited only a marginally lower elongation to failure as compared to the base alloy at all the temperatures investigated. The B modified alloy exhibited dynamic strain aging in the temperature range 400-475 °C which is similar to the observed behaviour in the base alloy.     

Pressure drop prediction in hydraulic transport of bi-dispersed particles of coal and copper ore in pipeline

Hydraulic transport studies with coal and copper ore have been carried out in a 0.0254 m and a 0.019 m diameter pipeline to observe the effect of solids concentration, surface characteristics and particle size distribution on pressure drop. The coarse coal showed a lower pressure drop than the fines at any velocity of suspension, whereas copper ore, exhibited the opposite trend. It has been observed, that the pressure drop for hydraulic transportation of bi-dispersed particles is a minimum at certain weight proportions of coarse to fines, as compared to that for the transportation of either of the single size. Based on the experimental results, an empirical expression was developed for the prediction of pressure gradient.     

Effect of temperature and hold time on internal hardening behavior of a near α titanium alloy under cyclic deformation

In the present work, the study of dynamic strain aging (DSA) in near α titanium alloy Timetal 834 is reported in terms of internal hardening variables (kinematic and isotropic hardening variable). Total strain controlled low cycle fatigue tests have been conducted in air at 300 °C and from 400 °C to 500 °C at a temperature interval of 25 °C at nominal strain rates of 6.67 × 10⁻³ s⁻¹. The alloy exhibits gradual cyclic softening till failure at 300 °C, whereas, it exhibits initial cyclic softening followed by marked cyclic hardening from 400 °C to 500 °C. The cyclic hardening is attributed to DSA phenomena, resulting due to increase in isotropic stress component. The observed maximum peak stress ratio, lower fatigue life and minimum half-life plastic strain range at 450 °C indicates the maximum effect of DSA at that temperature. The fatigue life of tensile and compressive hold at 450 °C was observed to be inferior as compared to pure fatigue tests.     

Fatigue crack growth behaviour of nickel based superalloys at ambient temperature

The present investigation deals with the study of fatigue crack growth rate (FCGR) behaviour of conventional IN 718 (Ni-0.02%C-19.0%Cr-19.35%Fe-3.0%Mo-5.10%Nb-0.50%Al-1.00%Ti-0.0033%B, all in wt%) and modified IN 718 (Ni-0.02%C-19.04%Cr-19.31%Fe-3.04%Mo-4.73%Nb-1.01%Al-1.16%Ti-0.0033%B, all in wt%) alloys at ambient temperature. Modified IN 718 alloy exhibits enhanced crack growth resistance due to roughness induced crack closure as compared to conventional IN 718 alloy.     

A dual-purpose positioner-fixture for precision six-axis positioning and precision fixturing: Part I. Modeling and design

This paper introduces a moving groove fixture which can be operated in two modes; as (1) a precision fixture or (2) a six-axis nanopositioner. Actuators and flexure bearings are integrated within the structural loop of the fixture, thereby enabling controlled changes in fixtured orientation and position while retaining high fixture stiffness. The combination of positioner and fixture characteristics enables one to adjust the fixtured position/orientation and then repeatably fixture about that position/orientation. Models of the fixture's six-axis kinematic characteristics and stiffness were generated and used to design a prototype.     

Soft Error Rate Reduction Using Circuit Optimization and Transient Filter Insertion

This paper describes a tunable transient filter (TTF) design for soft error rate reduction in combinational logic circuits. TTFs can be inserted into combinational circuits to suppress propagated single-event transients (SETs) before they can be captured in latches or flip-flops. TTFs are tuned by adjusting the maximum width of the propagated SET that can be suppressed. A TTF requires 6–14 transistors, making it an attractive cost-effective option to reduce the soft error rate in combinational circuits. A global optimization approach based on geometric programming that integrates TTF insertion with dual-V _DD and gate sizing is described. Simulation results for the 65 nm process technology indicate that a 17–48× reduction in the soft error rate can be achieved with this approach.     

Towards impedance-based temperature estimation for Li-ion battery packs

In order to meet the required power and energy demand of battery-powered applications, battery packs are constructed from a multitude of battery cells. For safety and control purposes, an accurate estimate of the temperature of each battery cell is of vital importance. Using electrochemical impedance spectroscopy (EIS), the battery temperature can be inferred from the impedance. However, performing EIS measurements simultaneously at the same frequency on each cell in a battery pack introduces crosstalk interference in surrounding cells, which may cause EIS measurements in battery packs to be inaccurate. Also, currents flowing through the pack interfere with impedance measurements on the cell level. In this paper, we propose, analyse, and validate a method for estimating the battery temperature in a battery pack in the presence of these disturbances. First, we extend an existing and effective estimation framework for impedance-based temperature estimation towards estimating the temperature of each cell in a pack in the presence of crosstalk and (dis)charge currents. Second, the proposed method is analysed and validated on a two-cell battery pack, which is the first step towards development of this method for a full-size battery pack. Monte Carlo simulations are used to find suitable measurement settings that yield small estimation errors and it is demonstrated experimentally that, over a range of temperatures, the method yields an accuracy of ±1°C in terms of bias, in the presence of both disturbances.