Showing papers by "PSG College of Technology published in 2006"

Pareto analysis of critical success factors of total quality management: A literature review and analysis

Abstract: Purpose – The purpose of this literature review is to identify and propose a list of few vital critical success factors (CSFs) of total quality management (TQM) for the benefit of researchers and industries.Design/methodology/approach – Even though there has been a large number of articles published related to TQM in the last few decades, only a very few articles focused on documenting the CSFs of TQM using statistical methods. The main objective of this literature review is to investigate and list the CSFs of TQM according to the descending order of frequencies of occurrences. The domain of review is the scale development studies and the TQM effect versus performance measurement studies. The review period is between 1989 and 2003. Rigorous statistical reliability tests and validity tests were conducted during these studies to factorize the CSFs and hence these studies were chosen for the literature review. Finally, the quality tool “Pareto analysis” was used to sort and arrange the CSFs according to the ...

Dry sliding wear behavior of Al 2219/SiCp-Gr hybrid metal matrix composites

Abstract: The dry sliding wear behavior of Al 2219 alloy and Al 2219/SiCp/Gr hybrid composites are investigated under similar conditions. The composites are fabricated using the liquid metallurgy technique. The dry sliding wear test is carried out for sliding speeds up to 6 m/s and for normal loads up to 60 N using a pin on disc apparatus. It is found that the addition of SiCp and graphite reinforcements increases the wear resistance of the composites. The wear rate decreases with the increase in SiCp reinforcement content. As speed increases, the wear rate decreases initially and then increases. The wear rate increases with the increase in load. Scanning electron microscopy micrographs of the worn surface are used to predict the nature of the wear mechanism. Abrasion is the principle wear mechanism for the composites at low sliding speeds and loads. At higher loads, the wear mechanism changes to delamination.

Removal of ocular artifacts from EEG using adaptive thresholding of wavelet coefficients

Abstract: Electroencephalogram (EEG) gives researchers a non-invasive way to record cerebral activity. It is a valuable tool that helps clinicians to diagnose various neurological disorders and brain diseases. Blinking or moving the eyes produces large electrical potential around the eyes known as electrooculogram. It is a non-cortical activity which spreads across the scalp and contaminates the EEG recordings. These contaminating potentials are called ocular artifacts (OAs). Rejecting contaminated trials causes substantial data loss, and restricting eye movements/blinks limits the possible experimental designs and may affect the cognitive processes under investigation. In this paper, a nonlinear time-scale adaptive denoising system based on a wavelet shrinkage scheme has been used for removing OAs from EEG. The time-scale adaptive algorithm is based on Stein's unbiased risk estimate (SURE) and a soft-like thresholding function which searches for optimal thresholds using a gradient based adaptive algorithm is used. Denoising EEG with the proposed algorithm yields better results in terms of ocular artifact reduction and retention of background EEG activity compared to non-adaptive thresholding methods and the JADE algorithm.

Friction and Wear Characteristics of Carbon-epoxy and Glass-epoxy Woven Roving Fiber Composites:

Abstract: Polymer materials when reinforced with high modulus fibers yield higher strength, higher stiffness, better toughness, and good dimensional stability. Fiber reinforcements are effective in reducing wear in adhesive situations in addition to increasing the strength and stiffness. The adhesive conditions are generally encountered in automotive and aerospace applications. In such applications, the types of reinforcement material used are important from the point of improved performance under different tribo situations. In this particular investigation, carbon-epoxy (C-E) composite is compared with that of glass-epoxy (G-E) composites for tribological properties using a pin-on-disc set up. The tests are conducted by subjecting C-E samples sliding against a hard steel disc (62 HRC) under different sliding and loading conditions. This article highlights the friction and wear behavior of these composites run for a constant sliding distance, where in the C-E composites show lower friction and lower slide wear loss...

Hydrophilic nanofibrous structure of polylactide; fabrication and cell affinity

Abstract: Microstructure and architecture of the scaffolds along with the surface chemistry exert profound effect on biological activity (cell distribution, proliferation, and differentiation). For the biological activity, scaffolds in tissue engineering have been widely designed. The objective of this study was to develop hydrophilic nanofibrous structure of polylactides (PLLA) polymer in the form of nonwoven mat by electrospinning technique, and further evaluate the fibroblast NIH3T3 cell proliferation, morphology, and cell–matrix interaction. Hydrophilicity of the PLLA fibers was improved by adding small fraction of low molecular weight polyethylene glycol (PEG) into the electrospinning solution. Four different ratio types (100/0, 80/20, 70/30, and 50/50) of PLLA/PEG electrospun matrices were fabricated, and the pore characteristics, tensile properties, contact angle, and hydrolytic degradation were observed. Furthermore, scanning electron microscope (SEM) and fluorescence actin staining images were used for micro-observation of cell–matrix interaction and cell morphology. It was found that the electrospun mat of PLLA/PEG (80/20), composed of fibers with diameters in the range 540–850 nm, majority of pore diameter less than 100 μm, tensile strength 8 MPa, elongation 150%, porosity more than 90%, and improved hydrophilicity with slow hydrolytic degradation, is favorable for biological activity of NIH3T3 fibroblast cell. Based on these results, the correct composition of PLLA and PEG in the porous electrospun matrix (i.e., PLLA/PEG (80/20)) will be a better candidate rather than other compositions of PLLA/PEG as well as hydrophobic PLLA for application in tissue engineering. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006

Pareto archived simulated annealing for job shop scheduling with multiple objectives

Abstract: In this paper, the job shop scheduling problem is studied with the objectives of minimizing the makespan and the mean flow time of jobs. The simultaneous consideration of these objectives is the multi-objective optimization problem under study. A metaheuristic procedure based on the simulated annealing algorithm called Pareto archived simulated annealing (PASA) is proposed to discover non-dominated solution sets for the job shop scheduling problems. The seed solution is generated randomly. A new perturbation mechanism called segment-random insertion (SRI) scheme is used to generate a set of neighbourhood solutions to the current solution. The PASA searches for the non-dominated set of solutions based on the Pareto dominance or through the implementation of a simple probability function. The performance of the proposed algorithm is evaluated by solving benchmark job shop scheduling problem instances provided by the OR-library. The results obtained are evaluated in terms of the number of non-dominated schedules generated by the algorithm and the proximity of the obtained non-dominated front to the Pareto front.

Mechanical behavior of isothalic polyester-based untreated woven jute and glass fabric hybrid composites

Abstract: In this study, the effect of hybridization on mechanical properties of untreated (as received) woven jute and glass fabric-reinforced isothalic polyester composites has been evaluated experimentally. Hybrid laminates are fabricated using hand lay-up technique. The specimen preparation and testing are carried out as per ASTM standards. The values of mechanical properties of hybrid composites plotted against glass fiber weight fraction show significant improvement after the inclusion of glass fiber. Addition of 16.5 wt% glass fiber, in a total fiber weight fraction of 42% enhances the tensile, flexural, and interlaminar shear strength (ILSS) by 37, 31.23, and 17.6% respectively. The behavior of the composite under different tests is analyzed with the help of performance curves. Water absorption plots for different periods of immersion indicated that jute– glass hybrid composites offer better resistance to water absorption. The results of fractographic tests carried out to study the modes of fracture, fiber–...

Breast Tissue Classification Using Statistical Feature Extraction Of Mammograms

Abstract: In this paper authors have made an attempt to classify the breast tissue based on the intensity level of histogram of a mmammogram,Statistical features of a mammogram are extrcted using simple image processing techniques.The proposed scheme uses texture models to capture the mammographic appearance within the breast. Parenchymal density patterns are modeled as a statistical distribution of clustered filter responses in a low dimensional space. The statistical features extracted are the mean,standard deviation, smoothness, third moment, uniformity and entropy which signify the important texture features of breast tissue.Based on the values of these features of a digital mammogram, the authors have made an attempt to classify the breast tissue in to four basic categories like fatty, uncompressed fatty, dense and high density. This categorizaton would help a radiologist to detect a normal breast from a cancer affected breast so as to proceed with further investigation.This forms a basic step in the detection of abnormal breast under computer aided detection system. The results obtained out of the proposed technique has been found better compared to the other existing methods. The accuracy of the method has been verified with the ground truth given in the data base( mini-MIAS database) and has obtained accuracy as high as 78% This is a basic step in the development of a CAD for mammo analysis being developed at the department of ECE in support with thePSG Research centre at Coimbatore-India.

A review of vector quantization techniques

Abstract: The fundamental principles of quantization and the two basic types of quantization techniques-scalar and vector-have been introduced. The concept of VQ, its salient features, design of code book, and advantages/disadvantages has been dealt with in detail. VQ is a data compression technique, producing a reconstruction with as small a distortion as possible. The quality of the reconstruction depends on the amount of data that is discarded. The performance of different classes of VQ techniques like structured and unstructured VQ, memory and memoryless VQ, the types of VQ under each of these categories have been discussed. This article has surveyed these to a certain extent, and much more remains if a detailed analysis is required

Dry sliding wear behavior of metal matrix composites: A statistical approach

Abstract: The dry sliding wear behavior of SiCp and SiCp-graphite-reinforced aluminum alloy composites produced by liquid metallurgy is studied by means of a pin-on-disc type of wear-test rig. This study evaluates the influence of independent parameters such as sliding speed (S), applied load (L), and sliding distance (D) on dry sliding wear behavior of composites. A Taguchi design for the experiments is used to collect the data in a controlled way, and a linear regression model is developed. This article tries to model dry sliding wear with wear parameters using a statistical approach. The results obtained in this work enable the influence and significance of various parameters and their interactions to be better understood. It was found that SiCp-Gr (graphite)-reinforced composites exhibit less volume loss when compared with SiCp-reinforced composites. Sliding speed is the most significant factor affecting wear behavior followed by L and D. The effect of interactions between the S and the L is more pronounced in SiCp-Gr composites.

Hydrogen bonding in substituted formic acid dimers.

Abstract: The hydrogen-bonded dimers of formic acid derivatives XCOOH (X = H, F, Cl, and CH3) have been investigated using density functional theory (B3LYP) and second-order Moller−Plesset perturbation (MP2) methods, with the geometry optimization carried out using 6-311++G(2d,2p) basis set. The dimerization energies calculated using aug-cc-pVXZ (with X = D and T) basis have been extrapolated to infinite basis set limit using the standard methodology. The results indicate that the fluorine-substituted formic acid dimer is the most stable one in comparison to the others. Topological analysis carried out using Bader's atoms in molecules (AIM) theory shows good correlation of the values of electron density and its Laplacian at the bond critical points (BCP) with the hydrogen bond length in the dimers. Natural bond orbital (NBO) analysis carried out to study the charge transfer from the proton acceptor to the antibonding orbital of the X−H bond in the complexes reveals that most of the dimers are associated with conven...

Performance evaluation of priority dispatching rules in multi-level assembly job shops with jobs having weights for flowtime and tardiness

Abstract: The problem of scheduling in dynamic shops is an important operational problem in view of its complexity and significance in terms of associated costs of scheduling. While a number of research studies have investigated the problem of scheduling in flow shops and job shops, only some attempts have been done to study the problem of scheduling in assembly job shops that manufacture multi-level jobs. The problem of scheduling in dynamic assembly job shops with jobs having weights for holding and tardiness of jobs deserves due attention. In this study an attempt has been made to propose new priority dispatching rules that minimize the performance measures related to weighted flowtime and weighted tardiness of jobs. The existing unweighted dispatching rules have been modified in view of the consideration of weights for flowtime and tardiness of jobs. The performances of the (modified) existing dispatching rules and the proposed dispatching rules are compared through exhaustive simulation experiments with the consideration of a number of different experimental settings involving due-date setting, utilization levels and types of job structures. The proposed dispatching rules are found to perform better than the existing ones in most experimental settings and with respect to a number of measures of performance.

Turning of particulate metal matrix composites — review and discussion:

Abstract: Metal matrix composites (MMCs) have emerged as an important class of materials, which are increasingly being utilized in recent years. Application of these materials in certain areas is limited due to difficulties in machining. The principal machining parameters that control machinability characteristics are extrinsic parameters (cutting speed, feed rate, depth of cut, and type of cutting tools) and intrinsic parameters (particulate size, volume fraction, and type of reinforcement). Different cutting tools used in machining these materials are given in the order of decreasing hardness as PCD, CBN, TiC, Si3N4, Al2O3, and WC. The present review is focused on the influence of cutting parameters, morphology, distribution, and volume fraction of reinforcement on the surface finish, tool life, cutting forces, and chip formation. This review will provide an insight into selecting the optimum machining parameters for machining metal matrix composites.

Morphology and growth aspects of Cr(N) phases on gas nitridation of electroplated chromium on AISI 316 LN stainless steel

Abstract: A gas-phase nitridation procedure has been investigated using a home-assembled TGA-MS system to enhance the high-temperature hardness and wear resistance of electroplated chromium on AISI 316 LN austenitic stainless steel. The sluggish diffusion kinetics of nitrogen in chromium and the presence of a thin oxide layer at the surface are the major constraints encountered during low-temperature gas nitridation process. This paper attempts to bring out a detailed correlation of the effect of nitridation environment, ammonia dissociation rate, substrate temperature and catalytic role of a thin nickel layer, on the nitriding characteristics towards addressing the above-mentioned limitations. XRD and SEM investigations on the nitrided specimens unambiguously reveal the morphology and the distribution of CrN and Cr 2 N phases formed during nitridation.

Theory and practice of total quality function deployment

Abstract: Purpose – This article seeks to propose a technique called total quality function deployment (TQFD) and to appraises its practicality by applying it to a traditional pump‐manufacturing environment.Design/methodology/approach – The deficiencies of QFD techniques were studied. The theory of the TQFD technique was developed with the objective of overcoming these deficiencies. Two pump‐manufacturing companies were involved, while examining the practicality of TQFD technique.Findings – A traditional pump‐manufacturing environment lacks knowledge of implanting techniques like QFD, which challenges the researchers to test‐implement, the techniques like TQFD. Yet the successful development of TQFD documents during the reported research project indicates the practical feasibility of TQFD implementation in pump‐manufacturing companies.Research limitations/implications – The practicality of TQFD was tested by involving two pump‐manufacturing companies located in the city of Coimbatore in India. These two companies m...

Generation of artificial earthquake motion records using wavelets and principal component analysis

Abstract: In the last century alone two to three million people died in earthquakes; More than 240 000 perish in Tangshan earthquake in China, 20 000 in the Izmit [Ikeya, 2004] 50 000 in India Bhuj earthquake, 100 000 in Sumatra and 90 000 in Pakistan earthquakes. Earthquake engineering has progressed to the stage where it is now computationally practical and desirable to perform a dynamic analysis of most civil engineering structures. Such an analysis requires the engineer to create an accurate analytical model of the structures as well as prescribe an earthquake input excitation. The design earthquake input excitation for the site under consideration is usually prescribed in the form of response spectra or in the form of an ensemble of artificial earthquake acceleration time histories. There is every need for generating artificial accelerograms since recorded accelerograms are very limited at site. This paper proposes five neural network based models for the generation of artificial earthquake and response spectra using wavelet transforms (WT) and principal component analysis (PCA) where the recorded accelerograms are limited at site of interest. The proposed model is compared with Lee and Han's model. The data for 25 earthquakes are taken for training and 4 for testing. Just like response spectra, this is also a convenient way of obtaining the design solution to a structural dynamics problem and is certainly an important tool.

A novel control strategy for the boost DC - AC inverter

Abstract: Boost DC-AC inverter naturally generates in a single stage an AC voltage whose peak value can be lower or greater than the DC input voltage. The main drawback of this structure deals with its control. Boost inverter consists of Boost DC-DC converters that have to be controlled in a variable-operation point condition. The sliding mode control has been proposed as an option. However, it does not directly control the inductance averaged-current. This paper proposes a control strategy for the Boost inverter in which each Boost is controlled by means of a double-loop regulation scheme that consists of a new inductor current control inner loop and an also new output voltage control outer loop. These loops include compensations in order to cope with the Boost variable operation point condition and to achieve a high robustness to both input voltage and output current disturbances. As shown by simulation results, the proposed control strategy achieves a very high reliable performance, even in difficult transient situations such as nonlinear loads, abrupt load changes, short circuits, etc., which sliding mode control cannot cope with.

Computer aided decision system for early detection of breast cancer.

Abstract: Background & objectives: Mammography is currently the method of choice for early detection of breast cancer in women. However, the interpretation of mammograms is largely based on radiologist’s opinion. In this study an attempt is made to develop an image processing algorithm for the detection of microcalcifications and also a computer based decision system for early detection of breast cancer.The proposed method deals with a novel approach for the development of a computer aided decision (CAD) system for early detection of breast cancer by mammogram image analysis. Methods: The proposed method employs simple thresholding the region of interest and the use of filters for clear identification of microcalcifications. The method suggested for the detection of microcalcifications from a mammogram image segmentation and analysis was tested over several images taken from mini-MIAS (Mammogram Image Analysis Society,UK) database. The algorithm was implemented using Metlab codes programming and hence can work effectively on a simple personal computer with digital mammogram as stored data for analysis. Results: The algorithm works faster so that any radiologist can take a clear decision about the appearance of microcalcifications by visual inspection of digital mammograms. The performance of the algorithm was tested over several images and the validation of results by visual inspection were done by an expert radiologist. Also, the system has given good detection rate as high as 78 per cent. The performance analysis of the CAD algorithm was done by receiver operating characteristics (ROC) plot. Interpretation & conclusion: The CAD system suggested here was capable of detecting microcalcifications with a high detection rate, and thus could be used for early detection of breast cancer.

Design and implementation of high power DC-DC converter and speed control of DC motor using TMS320F240 DSP

Abstract: This paper describes the design and implementation of high power DC-DC step- up converter using analog control circuits and speed control of DC motor using TMS320F240 DSP. In this technique a 24 V DC input supply is converted into 135 V DC by two-stage conversion. The full bridge topology is proposed for step up the DC voltage. The output of step-up converter is provided to the capacitive accumulator circuit, which consists of 1.2 F capacitor bank in it. The capacitive accumulator is mainly used to compensate peak power demand of the load for a transient period when sudden changes occur at load side and to store the energy under regenerative braking condition of DC motor. The capacitive accumulator circuit provides a constant voltage to the DC chopper under normal working condition. The closed loop speed control of DC motor is achieved using TMS320F240. The current and speed feed back are compared with their references respectively to achieve the speed control of DC motor, which is used in military application. The hardware has been developed and tested for laboratory conditions.

ResearchPattern Classification using imaging techniques for Infarct andHemorrhage Identification in the Human Brain

Abstract: Medical Image analysis and processing has great significance in the field of medicine, especially in Non- invasive treatment and clinical study. Medical imaging techniques and analysis tools enable the Doctors and Radiologists to arrive at a specific diagnosis. Medical Image Processing has emerged as one of the most important tools to identify as well as diagnose various disorders. Imaging helps the Doctors to visualize and analyze the image for understanding of abnormalities in internal structures. The medical images data obtained from Bio-medical Devices which use imaging techniques like Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Mammogram, which indicates the presence or absence of the lesion along with the patient history, is an important factor in the diagnosis. The algorithm proposes the use of Digital Image processing tools for the identification of Hemorrhage and Infarct in the human brain, by using a semi-automatic seeded region growing algorithm for the processing of the clinical images. The algorithm has been extended to the Real-Time Data of CT brain images and uses an intensity-based growing technique to identify the infarct and hemorrhage affected area, of the brain. The objective of this paper is to propose a seeded region growing algorithm to assist the Radiologists in identifying the Hemorrhage and Infarct in the human brain and to arrive at a decision faster and accurate.¢Lp¤L

Investigations on the mechanical behaviour of rough surfaces of TiNi thin films by nano indentation studies

Abstract: Nano hardness tests were conducted on TiNi thin films deposited by sputtering of a mosaic target comprising of segments of Titanium and Nickel. The composition of the films was determined by alpha particle back scattering (RBS). Surface topography of the films, imaged using an AFM, revealed high surface roughness, comparable to the indentation depth, leading to a large scatter and erroneous results from the indentation data. The objectives of the present investigation were (i) to extract the actual hardness of the film from the nano indentation data and (ii) to analyse the contact mechanisms during penetration of the indenter into the film by applying a statistical model of the surface roughness. Various mechanical parameters pertaining to the indentation process, namely, the point of first yield and the plasticity index of the film after deformation have been calculated. Variation of the deformation behaviour of the films as the asperity sizes increase is also reported.

New methodology for a person identification system

Abstract: Reliable person identification is a key factor for any safety measure. Unlike other biometrics such as the palm, retina, gait, face and fingerprints, the characteristic of the iris is stable in a person’s lifetime. Iris patterns are chaotically distributed and well suited for recognizing persons throughout their lifetime with a single conscription. This paper proposes a new approach to person recognition based on iris patterns, which works with indoor outdoor conditions, spectacles contact lens wearing persons and diseased eyes. A challenge-response method is used for eye aliveness checking that puts off artificial sources from entering the iris database. The proposed algorithm can work with 84 statistical iris features that are extracted from an individual. Space and time complexity of the proposed approach is lesser than the existing methods. This algorithm has been implemented and results have been analysed on 2500 different iris patterns acquired in India under different real-time conditions. Experimental results illustrate that the proposed method has been easily espoused in elections, bank transactions and other security applications.