A generalized plane-strain crack density-based model for evaluating the finite fracture toughness of composite laminates

The present study focuses on a developed crack density-based model for evaluating the material properties of an orthotropic composite ply containing a specified matrix-cracking density. Furthermore, more complementary details of this model, including a closed form solution for evaluating the stress fields as well as stiffness degradation of a damaged ply, will be presented. The derived relations will be applied for evaluating the master plot curve, which is applicable for obtaining the finite fracture toughness (G_mc) of laminated composites. The obtained results will be compared with the available experimental results.     

ISDN frame relay and its congestion control

Frame relay is a new ISDN (integrated services digital network) packet mode bearer service which is expected to provide an efficient means of information transport using high-speed transmission media. Several new applications requiring high bandwidth, such as file transfer, video and packetized voice, are suitable candidates to use this streamlined protocol. However, as there are no control frames present within the network for traffic flow management, congestion may arise during periods of peak offered loads. Efficient congestion control mechanisms are needed to make the frame relay effective. In this paper, after a brief discussion of the frame relay protocol, we consider the congestion problem in networks using this protocol and evaluate the performance. Specifically, we consider static and dynamic window flow control methods and develop models to determine the throughput under various load conditions. The throughput of the static window flow control model is determined by computing the frame loss probability and the virtual retransmission time, which is the time between arrivals of retransmitted frames at the destination. The frame loss probability is calculated by modelling the bottleneck resource as a finite state Markov chain. The results are validated by simulation. Furthermore, to analyse the dynamic interactions between the virtual circuits and their effect on the throughput and delay characteristics, we develop a simulation model which incorporates a dynamic window congestion control mechanism. It is shown that when the offered load is high, the performance of dynamic window flow control is superior to that of static window flow control.     

Controlled Theophylline Release from Microcapsules of Acrylic & Methacrylic Acid Ester Copolymer

The goal of this work was to develop a suitable method for microencapsulation of theophylline using copolymer of acrylate and methacrylate ester (EUDRAGIT) as the coating material. The effect of protective colloids on the process of microencapsulation was evaluated. The in vitro studies revealed significant control of drug release for the developed dosage form. Individually, the polymer coated drug particles of different core: coat ratio and different proportions of protective colloids were found to influence the pharmacokinetic parameters as revealed from the in vivo bioavailability studies in gastric-emptying controlled rabbits. In vivo bioavailability data were compared using Westlake's confidence limit.     

Automatic target scoring system using machine vision

This paper reports on the development of a machine vision system for assessing targeting accuracy of ballistic, projectile-firing, weapon systems. The machine vision system developed here can monitor the target continuously, report precise quantitative targeting information, and simultaneously provide a color-coded display of impacts. The only other automated target scoring system on the market today is based on the analysis of acoustic signatures of projectiles using a heavily instrumented target. The proposed vision-based technique, in contrast, is inherently passive, requiring little or no modification of the existing set up.     

Closed-Form Modeling and Analysis of an XY Flexure-Based Nano-Manipulator

Flexure-based mechanisms are widely utilized in nano manipulations. The closed-form statics and dynamics modeling is difficult due to the complex topologies, the inevitable compliance of levers, the Hertzian contact interface, etc. This paper presents the closed-form modeling of an XY nano-manipulator consisting of statically indeterminate symmetric(SIS) structures using leaf and circular flexure hinges. Theoretical analysis reveals that the lever's compliance, the contact stiffness, and the load mass have significant influence on the static and dynamic performances of the system.Experiments are conducted to verify the effectiveness of the established models. If no piezoelectric actuator(PEA) is installed, the influence of the contact stiffness can be eliminated. Experimental results show that the estimation error on the output stiffness and first natural frequency can reach 2% and 1.7%, respectively. If PEAs are installed, the contact stiffness shows up in the models. As no effective method is currently available to measure or estimate the contact stiffness, it is impossible to precisely estimate the performance of the overall system. In this case, the established closed-form models can be utilized to calculate the bounds of the performance. The established closed-form models are widely applicable in the design and optimization of planar flexure-based mechanisms.     

Microstructure dependence of ion transport in glass-nanocomposites

Glass-nanocomposites are produced when crystallite particles of nanometer dimension are dispersed or embedded within the glass matrix. In this work we     

Integrating AHP with QFD for robot selection under requirement perspective

Selection of a robot is an important task, as improper selection may adversely affect a firm's production by reducing the quality of the product, thereby reducing productivity as well as profitability. To effectively select a robot for a specified job, several factors have to be considered. The objective of this paper is to explain how, using a combined AHP/QFD model, the authors are able to determine if the deployment of robots in industry helped in performance enhancement from requirement perspective. Incorporating a simple and novel cost factor measure in the proposed integrated AHP/QFD model aids justification of the implementation of a robotic system in a manufacturing firm from an economic point of view also. The proposed integrated approach also identifies technical requirements followed by customer requirements. In this paper, an integrated model combining AHP and QFD has been delineated for the industrial robot selection problem. Seven technical requirement factors have been considered for the case study.     

An empirical relationship to determine lateral seismic response of mid‐rise building frames under influence of soil–structure interaction

In this study, to determine the elastic and inelastic structural responses of mid‐rise building frames under the influence of soil–structure interaction, three types of mid‐rise moment‐resisting building frames, including 5‐storey, 10‐storey and 15‐storey buildings are selected. In addition, three soil types with the shear wave velocities less than 600 m/s, representing soil classes C_e, D_e and E_e according to AS 1170.4–2007 (Earthquake action in Australia, Australian Standards), having three bedrock depths of 10 m, 20 m and 30 m are adopted. The structural sections are designed after conducting nonlinear time history analysis, on the basis of both elastic method and inelastic procedure considering elastic‐perfectly plastic behaviour of structural elements. The frame sections are modelled and analysed, employing finite difference method adopting FLAC2D software under two different boundary conditions: (a) fixed base (no soil–structure interaction) and (b) considering soil–structure interaction. Fully nonlinear dynamic analyses under the influence of different earthquake records are conducted, and the results in terms of the maximum lateral displacements and base shears for the above mentioned boundary conditions for both elastic and inelastic behaviours of the structural models are obtained, compared and discussed. With the results, a comprehensive empirical relationship is proposed to determine the lateral displacements of the mid‐rise moment‐resisting building frames under earthquake and the influence of soil–structure interaction. Copyright © 2012 John Wiley & Sons, Ltd.     

An experimental study on the performance and emission characteristics of a CI engine fuelled with Jatropha biodiesel and its blends with diesel

The performance and emission characteristics of a compression ignition engine using mixture of jatropha biodiesel and mineral diesel have been experimentally investigated. It is observed that brake specific fuel consumption increases with higher percentage of biodiesel in the blends. Brake thermal efficiency decreases with the increased percentage of biodiesel in the blends. The maximum efficiency is found to be 29.6% with pure diesel and 21.2% with pure biodiesel. Carbon mono-oxide and hydrocarbon emissions are improved with the addition of biodiesel to diesel. NO_x emission is found to be increased with pure biodiesel by 24% compared to mineral diesel.     

A method for detection and classification of events in neural activity

We present a method for the real time prediction of punctuate events in neural activity, based on the time-frequency spectrum of the signal, applicable both to continuous processes like local field potentials (LFPs) as well as to spike trains. We test it on recordings of LFP and spiking activity acquired previously from the lateral intraparietal area (LIP) of macaque monkeys performing a memory-saccade task. In contrast to earlier work, where trials with known start times were classified, our method detects and classifies trials directly from the data. It provides a means to quantitatively compare and contrast the content of LFP signals and spike trains: we find that the detector performance based on the LFP matches the performance based on spike rates. The method should find application in the development of neural prosthetics based on the LFP signal. Our approach uses a new feature vector, which we call the 2d cepstrum.