362 research outputs found

    Effect of dead space on avalanche speed

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    The effects of dead space (the minimum distance travelled by a carrier before acquiring enough energy to impact ionize) on the current impulse response and bandwidth of an avalanche multiplication process are obtained from a numerical model that maintains a constant carrier velocity but allows for a random distribution of impact ionization path lengths. The results show that the main mechanism responsible for the increase in response time with dead space is the increase in the number of carrier groups, which qualitatively describes the length of multiplication chains. When the dead space is negligible, the bandwidth follows the behavior predicted by Emmons but decreases as dead space increase

    SYNTHESIS OF POTASSIUM-S-1,2- DIHYDROXYPROPYLSULPHONATE AND ITS INCORPORATION TO SYNTHESISE POLYESTER IONOMER

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    ABSTRACT: An anionic diol, potassium-S-1,2-dihydroxyprppylsulphonate, (SDOL) has been synthesised by using phase transfer catalyst, benzyltriethylammonium chloride and subsequently used for the preparation of polyester ionomer. A series of polyester were successfully synthesised by using different molar ratio of the ionic diol and propane diol. The monomer (ionic diol) and polyester were characterised by FTIR, 1 H NMR, TGA and DTG. The inherent viscosities of polyesters were in the range 0.38-1.21 dL/g. Key words: Polyester ionomer, benzyltriethylammonium chloride, ionic diol, potassium-S-1,2-dihydroxypropylsulphonate . I.INTRODUCTION Polyesters are a highly versatile class of polymers synthesized generally from a diacid and a diol. During the last 30 years, scientists have been fascinated by a class of polymers known as ionomers.Ionomers are normally defined as ion-containing polymers with a maximum content of ionic groups of about 15mol% or less along the backbone chains or as pendent groups. The modification and control of polymer properties through the use of ionic functional groups have received a considerable amount of attention in recent years. The common thread in most of the research efforts to date was the knowledge that the presence of even a small amount of covalently bonded ionic moieties in organic polymers is known to exert a profound effect on their physical and rheological properties. In fact ionomers have been shown to exhibit considerably higher moduli, and higher glass transition temperatures compared to their non-ionic analogues. Our research effort is directed towards the development of new polymer structures by introducing ionic groups (SDOL) into the polyester backbone. The first fibre-forming polyesters were prepared by Carothers and Hill in the late 1920s using the melt condensation of dicarboxylic acids and aliphatic diols. 1 Ionomers are materials of great technological interest due to the fact that the ionic groups can interact with each other disturbing the supramolecular structure and modifying their physical and chemical properties

    Non-neoplastic lesions of the ovary review

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    Abstract Ovary is an important organ as it is concerned with the production of progeny. commonest site of neoplastic and non age group and accounts for the most prevalent cause of hospital admissions. lesions are classified as inflammatory (infectious and non non-cystic) and pregnancy related disorders

    Online Signature Verification Using Energy, Angle and Directional Gradient Feature With Neural Network

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    Abstract: Signature used as a biometric is implemented in various systems as well as every signature signed by each person is distinct at the same time. It is very important to have anonline computerized signature Verification system differentiate digital signature. Hand written signature used every day at various places (Bank, Office etc) for the authentication of a person, but a signature of a person may not be same at different time or it may be generated by some fraud way. So therobust system is required for verification of the signature. The signature verification can be done either online or offline, here we are using online signature verification network. In the proposed system the signatures is taking as a image by the signature pad and apply image processing technique before the feature extraction to make the system effective. The angle, energy and chain code features are used in this paper to differentiate the signature. Neural network is used as a classifier for this system. The studies of online signature verification are given in this paper

    Clinicopathological study of viral skin lesions

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    Abstract Introduction: Many viral infections have prominent skin manifestations. simplex, molluscum contagiosum and human papilloma virus which causes verruca vulgaris, condyloma acuminatum, deep palmoplantar wart and verucca plana. They are of increased significance in immunocompromised patients. the viral lesions are diagnosed clinically and serologically, some require biopsy confirmation. identify the specific histological changes in individual viral lesions. To differentiate the lesions that can clinically mimi as bullous lesion or soft tissue mass. SMVMCH for a period of 3 years from 2011 to 2013 were taken for this study. studied, 31 patients were diagnosed to have skin manifestations of various viral infections. The most commonly encountered entity was Verruca molluscum contagiosum (4), herpes (2) and verucca plana the diagnosis were, intranuclear inclusions in herpes; cytoplasmic viral inclusion bodies in MC, deep palmoplantar wart; koilocytes in Verruca and condyloma .These were also associated with o produce warty, bullous and mass like lesions which can mimic non infectious conditions. Histopathological evaluation serves as a valuable tool for identification of virus induced skin changes and aids in approp lesions. In our study most common infection was HPV

    Detection of Black Hole Attack With Improved AODV Protocol in Manet

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    ABSTRACT:Ad-hoc network is a collection of dynamic nodes it means any node can join the network and leave the network any time. Wireless communication is less secure than wired communication and that's why it is the vulnerability of mobile ad-hoc network and any threat can easily affect the communication. Many types of attacks are developed today which badly crash the network and make the communication performance degrade. So for avoid these vulnerabilities and make network secure we propose the technique on SECURITY of mobile ad-hoc network. To provide the security of mobile ad-hoc network we generate new techniques for detection of black hole attack. Black hole attack is type of malicious node who drops the packet instead to send that packet to their destination

    Design of Low Power Counters Using Reversible Logic

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    ABSTRACT: In today's world, the complexity of the chip is increasing as more and more devices are being connected on a single chip. Due to the high density of the chip, the power dissipation increases demanding better power optimization methods. One of the methods to achieve power optimization is by using reversible logic. It can be used in low power CMOS designs, quantum computing, nanotechnology and optical computing. This paper presents an optimized sixteen-bit binary sequential counter based on reversible logic using Feynman, and Fredkin gates. Optimization of the sequential circuit is achieved on the basis of total number of gates used in the circuit and total number of garbage outputs generated. Circuits have been designed using Cadence Virtuoso Schematic Editor

    Talking Assistance about Location Finding both Indoor and Outdoor for Blind People

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    Abstract: God gifted sense to human being which is an important aspect in our life is vision. We are able to see the beauty of nature, things which happen in day-to-day life with the help of our eyes. But there are some people who lack this ability of visualizing these things. They face many difficulties to move on with their daily life. The problem gets worse when they move to an unfamiliar location. Visually impaired people face many challenges when moving in unfamiliar public places. Only few of the navigation systems for visually impaired people can provide dynamic interactions. None of these systems work perfectly both indoors and outdoors. Current navigation device for the visually impaired focus on travelling from one location to another. This focuses on designing a device for visually impaired people that help them to travelling independently also it must be comfortable to use. The proposed device is used for guiding individuals who are blind or partially sighted. The device is used to help blind people to move with the same ease and confidence as a sighted people. The device is linked with a GPS to identify the location of the blind person. Moreover, it provides the voice alert to avoid obstacles based on ultrasonic sensors. An emergency button is also added to the system. A RFID can be installed into public building and it is also integrated into blind persons walking stick .The whole device is designed to be small and is used in conjunction with the white cane

    Color Histogram Features for Image Retrieval Systems

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    ABSTRACT: Histogram features have proved powerful in the classification of image and object detection . The CBIR most efficient and searches the color based images. Here in this method we use some improved preprocessing steps, preprocessing algorithms and the image classification is analyzed. In CBIR image classification has to be computationally very fast and efficient. In this project a new approach is introduced, which based on low level image histogram features. Color is a main powerful descriptor that often identifies object and extraction scene. The main advantage of this method is the very quick generation and comparison of the applied feature vectors. Histograms are simple to calculate in software and also lend themselves to economic hardware implementations. A popular tool for a real-time image processing histogram-based image retrieval methods in two color spaces were exhaustively compared. The testing also highlights the weaknesses and strengths of the model. KEY WORDS: color-based and content based image retrieval, K-Nearest neighbor method, histogram intersection and its similarity
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