Bearing and uplift capacities of under-reamed piles in soft clay underlaid by stiff clay using lower-bound finite element limit analysis

Ensuring a safe foundation design in soft clay is always a challenging task to engineers. In the present study, the effectiveness of under-reamed piles in soft clay underlaid by stiff clay is numerically studied using the lower-bound finite element limit analysis (LB FELA). The bearing and uplift capacities of under-reamed piles are estimated through non-dimensional factors N_cul and F_cul, respectively. These factors increased remarkably and marginally compared to N_cul and F_cul of the piles without bulbs when the bulb is placed in stiff and soft clay, respectively. For a given ratio of undrained cohesion of stiff to soft clay (c₂/c₁), the factors N_cul and F_cul moderately increased with the increase in the length-to-shaft-diameter ratio (L_u/D) and adhesion factors in soft clay (α_s1) and stiff clay (α_s2). The variation of radial stress along the pile–soil interface, distribution of axial force in the under-reamed piles, and state of plastic shear failure in the soil are also studied under axial compression and tension. The results of this study are expected to be useful for the estimation of the bearing and uplift capacities of under-reamed piles in uniform clay and soft clay underlaid by stiff clay.     

VHF propagation characterization during atmospheric disturbances

Abstract

The propagation of a television (TV) signal is usually perturbed during periods of atmospheric disturbance such as in thunderstorms. The region under investigation here is situated in the coastal area of the Bay of Bengal and has experienced frequent thunderstorm activities. An investigation to study their effects on VHF signal propagation transmitted from Satkhira in Bangladesh and received at the Indian Statistical Institute, Calcutta, has been undertaken. The depths of the atmospheric disturbances within a 1?km range have been recorded and measured by acoustic sounder (sodar) operated continuously at the receiving station. The inset of the storm is marked by the enhanced signal level with deep fluctuations characteristic during the periods of thunderstorms.     

Nonlinear DC equivalent circuits for ferroelectric memristor and Its FSM application

Pt/BaTiO₃-BiFeO₃/Nb:SrTiO₃ based memristors were fabricated and their current–voltage (I–V) characteristics were studied in order to facilitate integration with analog/digital computations. Piecewise non-linear I–V characteristic equations of the ferroelectric memristor were obtained using non-linear regression techniques. An equivalent circuit for the fabricated memristors was obtained comprising of internal current, film resistance, and voltage dependent resistance. Utilizing the equivalent circuit model, a three bit general purpose Finite State Machine was developed and simulated results were found to match with the fabricated FSM device results.     

Effect of fuzzification on the plosive cognition system

Fuzzy algorithms provide a simpler and more powerful approach than statistical decision methods for describing non-ideal (fuzzy) environments in which there exists no precise boundary between the categories due to inherent vagueness rather than randomness. This paper attempts to demonstrate the effectiveness of such an algorithm when applied to the computer recognition of patterns of biological origin such as Telugu unaspirated plosives in initial position of large number of utterances in CVC context. A multieategorizer is described in which the fuzzy processor embodies a fuzzy property extractor and a similarity matrix generator. A provision fur controlling fuzziness in property sets had been made by keeping two parameters. ‘exponential’ and ‘denominational’ fuzzifiers, in the components of property matrices ; their effect on recognition score is also studied.

Machines’ performances are explained by plotting curves and through confusion matrices when transition, duration and slope of transition from the point of transient release of stop closure to the steady state of only first two formants were used as input features. Voiced stops are differentiated more easily than unvoiced stops, with the maximum overall recognition score ranging from 60% for dentals to 85% for bilabials. The fuzzy hedge ‘ slightly ’ when applied to property sets reduces the confusion from that of the hedge ‘ very ’ and consecutive utilizations of the operations ‘CONT’, ‘ OIL’ and ‘INT’ resulted in a wide variation of about 20 to 25% in the recognition score. Such a variation is found to be insignificant beyond an optimum value of the exponential fuzzifier’.     

A novel DNA-inspired encryption strategy for concealing cloud storage

Over the last few years, the need of a cloud environment with the ability to detect illegal behaviours along with a secured data storage capability has increased largely. This study presents such a secured cloud storage framework comprising of a deoxyribonucleic acid (DNA) based encryption key which has been generated to make the framework unbreakable, thus ensuring a better and secured distributed cloud storage environment. Furthermore, this work proposes a novel DNAbased encryption technique inspired by the biological characteristics of DNA and the protein synthesis mechanism. The introduced DNA based model also has an additional advantage of being able to decide on selecting suitable storage servers from an existing pool of storage servers on which the data must be stored. A fuzzy-based technique for order of preference by similarity to ideal solution (TOPSIS) multi-criteria decisionmaking (MCDM) model has been employed to achieve the above-mentioned goal. This can decide the set of suitable storage servers and also results in a reduction in execution time by keeping up the level of security to an improved grade. This study also investigates and analyzes the strength of the proposed S-Box and encryption technique against some standard criteria and benchmarks, such as avalanche effect, correlation coefficient, information entropy, linear probability, and differential probability etc. After the avalanche effect analysis, the average change in cipher-text has been found to be 51.85%. Moreover, thorough security, sensitivity and functionality analysis show that the proposed scheme guarantees high security with robustness.     

Adaptive learning algorithm in classification of fuzzy patterns An application to vowels in CNC context

An adaptive algorithm for recognition of ill-defined patterns using weak representative points and single pattern training procedure is presented from the standpoint of fuzzy set theory. The method includes both supervised and non-supervised schemes, A non-adaptive algorithm with fixed reference and weight vectors is also described to describe the efficiency of the system's adaptiveness to a new input.

This was implemented to machine recognition of vowel sounds of a number of speakers in Consonant-Vowel Nucleus-Consonant (CNC) context considering the first three vowel formants as input features. The decision of the machine is governed by the maximum value of fuzzy membership function. A recognition rate, particularly for weak initial representative vectors, was seen to be dependent on the sequence of incoming patterns. As the process of classification continued, the learned moan vectors approached their respective true values of the clusters. Again, once the optimum size of training set is obtained, the role of the external supervisor became insignificant.     

Monitoring changes in ecology in the Kudremukh mining region

Iron-ore deposits of the Kudremukh region in Karnataka State, India, were discovered at the beginning of the present century. These deposits have only recently begun to be exploited by the Kudremukh Iron Ore Company. As a result the land cover, particularly the grassland areas, are becoming disturbed.

This paper is the outcome of a joint study undertaken by three central and state government agencies in India for monitoring the ecological changes in the above region. Multitemporal LANDSAT MSS data together with aerial CIR photographs and ground data were used for the study. The study was mainly addressed to the mapping of land-cover changes, which is one of the most important indicators of ecological monitoring.     

A NEW METHOD OF DETERMINATION OF CALCIUM ORTHOPHOSPHATE AND ASSOCIATED IMPURITIES BY THERMOGRAVIMETRY AND DERIVATIVE THERMOGRAVIMETRY

Calcium orthophosphte (TCP) is known to be a nutritional additive in processed foods and wheat flour. Only pure salt is highly toxic to stored product insects. However, commercial salts were found to contain other monobasic and dibasic calcium phosphates and carbonates of calcium and magnesium which reduce insecticidal potency and affect food quality. The conventional methods of analysis of these salts are not only cumbersome but are not distinguished from each other clearly. A new method of identification of pure tricalcium phosphate and other associated impurities by thermogravimetry and derivative thermogravimetry has been described and the parameters for the identification of the nutritional protectant salt have been characterized.     

Optical and microstructural characterization of sol/gel derived cerium-doped PZT thin films

Optical properties of cerium-doped PZT thin films on sapphire prepared by a sol-gel technique are investigated using both transmission and reflection spectra in the wavelength range 200 to 900 nm. The refractive index, extinction coefficient and thickness of the film are determined from the measured transmission spectra. The packing density of the film is calculated from its refractive index using the effective medium approximation (EMA), and average oscillator strength and wavelength are estimated using a Sellmeir-type dispersion equation. Absorption coefficient (α) and the band gap energy (E_g) of each film composition are also calculated. Possible correlations of microstructure and phase formation behaviour with changes in band gap energy and other optical properties are discussed. This revised version was published online in November 2006 with corrections to the Cover Date.