Contrast enhancement of MRI images using morphological transforms and PSO

Medical imaging plays a crucial role in correct extraction of the significant information for monitoring the patient’s health and providing the quality treatment. A deluge of medical images requires initial interpretation for the presence of any abnormality, however, the correct diagnosis requires the images to be of good quality. To cope with the problem of poor contrast in medical images, this paper presents a method based on morphological transforms to improve the quality of the images. The proposed method incorporates Particle Swarm Optimization to find an optimum value of a parameter which controls the enhancement of the resulting image. The proposed algorithm is executed on a set of MRI images for testing its efficacy. The experimental results are compared in terms of both qualitative and quantitative parameters. The mean opinion score is obtained with the help of experts, which clearly shows the better performance of the proposed method. Furthermore, the parameters like Contrast Improvement Ratio, signal-to-noise ratio, peak signal-to-noise ratio, PL, and Structural Similarity Index are evident of better performance of proposed method when compared with the state-of-the-art methods and few recent methods. The comparison shows that the performance of the proposed method based on morphological transforms incorporating Particle Swarm Optimization is better not only visually but also in terms of other evaluation parameters.

     

Unconstrained handwritten document retrieval

With the ever-increasing growth of the World Wide Web, there is an urgent need for an efficient information retrieval system that can search and retrieve handwritten documents when presented with user queries. However, unconstrained handwriting recognition remains a challenging task with inadequate performance thus proving to be a major hurdle in providing robust search experience in handwritten documents. In this paper, we describe our recent research with focus on information retrieval from noisy text derived from imperfect handwriting recognizers. First, we describe a novel term frequency estimation technique incorporating the word segmentation information inside the retrieval framework to improve the overall system performance. Second, we outline a taxonomy of different techniques used for addressing the noisy text retrieval task. The first method uses a novel bootstrapping mechanism to refine the OCR’ed text and uses the cleaned text for retrieval. The second method uses the uncorrected or raw OCR’ed text but modifies the standard vector space model for handling noisy text issues. The third method employs robust image features to index the documents instead of using noisy OCR’ed text. We describe these techniques in detail and also discuss their performance measures using standard IR evaluation metrics.     

Fault containment in weakly stabilizing systems

Research on fine tuning stabilization properties has received attention for more than a decade. This paper presents probabilistic algorithms for fault containment. We demonstrate two exercises in fault containment in a weakly stabilizing system, which expedite recovery from single failures, and confine the effect of any single fault to the constant-distance neighborhood of the faulty process. The most significant aspect of the algorithms is that the fault gap, defined as the smallest interval after which the system is ready to handle the next single fault with the same efficiency, is independent of the network size. We argue that a small fault gap increases the availability of the fault-free system.     

Designing content distribution networks for optimal cost and performance

One strategy for alleviating excess latency (delay) in the Internet is the caching of web content at multiple locations. This reduces the number of hops necessary to reach the desired content. This strategy is used for web content such as html pages, images, streaming video, and Internet radio. The network of servers which store this content, and the collections of objects stored on each server, is called a content distribution network (CDN). In order to optimally design a CDN, given a network topology with available server storage capacity at various points in the network, one must decide which object collections to place on each server in order to achieve performance or cost objectives. The placements must be within the storage limits of the servers and must reflect the request patterns for each collection of objects to be cached. Researchers have suggested formulations for the CDN problem which address performance by minimizing latency (the average number of hops is a commonly accepted measure of latency) from client to content, or formulations that focus on minimizing cost of storage and/or bandwidth. In this research, we develop a model which allows for the simultaneous treatment of performance and cost, present examples to illustrate the application of the model and perform a detailed designed experiment to gain insights into cost/hops tradeoff for a variety of network parameters.     

Characterization and fracture behavior of bismuth–tin thermal fuse alloy wires produced by the Ohno continuous casting process

Bismuth–tin binary alloys containing high bismuth concentrations of 40 to 77% were continuously cast into wires of approximately 2 mm in diameter with casting speeds between 15 and 150 mm min^?1 using the Ohno Continuous Casting (OCC) process. The microstructure was examined and tensile tests were performed for wires cast at various speeds. It was found that for slowly cast wires containing large primary bismuth dendrites, bismuth fracture occurring along the (111) plane exerted a key role in wire fracture, while microstructures with refined bismuth dendrites exhibited a mixture of bismuth cracks and inter-phase decohesion, allowing the accommodation of larger strain before wire fracture. For wires with microstructures containing primary tin dendrites, inter-phase decohesion played a key role in wire fracture.     

Colorimetric detection of nucleic acid signature of shiga toxin producing Escherichia coli using gold nanoparticles

Enterohemorrhagic E. coil (EHEC) serotype O157:H7 is one of the major pathogens, responsible for the severe disease outbreaks. EHEC causes diseases in humans through production of shiga-like toxin leading to bloody diarrhea. The toxin is encoded by stx2 gene in E. coli. The current methodology for detection of EHEC relies on fluorogenic-substrate based culture media or nucleic acid amplification based Real-Time Polymerase Chain Reaction assays that are either time consuming or need expensive instrumentation. In this study, the optical properties of gold nanoparticles (GNPs) have been exploited for detection of nucleic acid of Escherichia coli O157:H7. The stx2 gene representing EHEC signature has been targeted using the gold nanoparticle probes. Gold nanoparticles (GNPs) of 20 +/- 0.2 nm were synthesised by citrate reduction method and characterised by spectroscopy and transmission electron microscopy. The GNPs were functionalised with 19 and 22 bp of thiolated single stranded DNA complementary to target highly conserved 149 bp region of stx2 gene. Transmission Electron Microscopy revealed the hybridization, aggregation and reduction in the interparticle distances of the GNP probes in the presence of target DNA. The aggregation and the spectral shift in the plasmon band observed with 10(6) copies of target DNA indicates feasibility of a simple and quick colorimetric 'spot and read' test in contrast to amplification based detection methods.     

Innovation in non-contact ultrasonic analysis: applications for hidden objects detection

 This paper describes unusual applications of ultrasound that are based upon recent advances in transduction efficiency in air and gaseous media. Piezoelectric transducer devices – capable of generating extremely high intensity ultrasound in ambient air up to 5 MHz – have been successfully developed and tested. This is in addition to the obvious uses for gas analysis, remote sensing, liquid level, gap, and thickness measurement, and proximity analysis. These new generation transducers make it possible to analyze solids and liquids not only non-destructively, but also without physically contacting the test sample. Among various applications to the non-destructive characterization (NDC) of industrial materials, we also describe the feasibility of a forensic application. This concerns the detection of objects such as knives, guns, contraband drugs, dead bodies, etc., hidden inside false compartments or walls. Received: 15 October 1997 / Accepted: 24 October 1997     

Effect of Ar heat treatment on oxygenated R1−x Ca x Ba2Cu3O7−δ (R = Y, Sm) superconductors

The influence of heat treatment, at 450°C in Ar environment, on oxygenated (6.72 < 7 – < 6.93) samples of R_1–x Ca _x Ba₂Cu₃O_7– (i.e. R(Ca)-123, with R = Y, Sm) with 0 < x < 0.3 has been investigated. Measurements of oxygen loss, normal state resistivity behaviour (T), superconducting critical temperature T _c and transition widths reveal that Ar treatment effects both the series differently. The Sm(Ca)-123 samples, for all values of x, show a considerable loss of oxygen ((x) = 0.4 to 0.6) and decrease in T _c (T _c(x) = 35 to 55 K). Whereas, surprisingly, the Y(Ca)-123 samples show a much smaller loss of oxygen ((x) = 0 to 0.3), along with a decrease in T _c for x < 0.2 and an increase in it for x > 0.2. In particular, the x = 0.3 sample shows a negligible change in oxygen content accompanied by an increase of 20 K in T _c. These and host of other observations suggest that the presence of Ca may influence the oxygen loss mechanism in these series.     

Simplified loss analysis and comparison of full-bridge,full-range-ZVS DC-DC converters

The loss of zero-voltage-switching (ZVS) of active switches has been a serious limitation of full-bridge (FBZVS) converters. Many techniques have been proposed in the past to extend the range of ZVS operation over the wider and also the full range of operation. However, in these techniques ZVS is achieved at the expense of additional conduction loss in active switches and losses in the auxiliary components. In this paper, the analysis for the additional losses in various full-range FBZVS DC-DC converters and their comparative evaluation is reported. Closed form expressions are derived for average value of device currents and losses. The loss curves for various topologies are plotted and compared. The analytical results are found to be consistent with the experimental efficiency tests performed on 500 W, 100 kHz prototype. It is concluded that a recently proposed new topology has the least penalty of additional losses.