9,088 research outputs found

    Three-isotope plot of fractionation in photolysis: A perturbation theoretical expression

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    The slope of the three-isotope plot for the isotopomer fractionation by direct or nearly direct photodissociation is obtained using a perturbation theoretical analysis. This result, correct to first order in the mass difference, is the same as that for equilibrium chemical exchange reactions, a similarity unexpected a priori. A comparison is made with computational results for N2O photodissociation. This theoretical slope for mass-dependent photolytic fractionation can be used to analyze the data for isotopic anomalies in spin-allowed photodissociation reactions. Earlier work on chemical equilibria is extended by avoiding a high-temperature approximation

    Discrete element weld model, phase 2

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    A numerical method was developed for analyzing the tungsten inert gas (TIG) welding process. The phenomena being modeled include melting under the arc and the flow in the melt under the action of buoyancy, surface tension, and electromagnetic forces. The latter entails the calculation of the electric potential and the computation of electric current and magnetic field therefrom. Melting may occur at a single temperature or over a temperature range, and the electrical and thermal conductivities can be a function of temperature. Results of sample calculations are presented and discussed at length. A major research contribution has been the development of numerical methodology for the calculation of phase change problems in a fixed grid framework. The model has been implemented on CHAM's general purpose computer code PHOENICS. The inputs to the computer model include: geometric parameters, material properties, and weld process parameters

    Compositional changes on GaN surfaces under low-energy ion bombardment studied by synchrotron-based spectroscopies

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    We have investigated compositional changes on GaNsurfaces under Ar-ion bombardment using synchrotron-based high-resolution x-rayphotoemission (PES) and near-edge x-ray absorption fine structure(NEXAFS)spectroscopy. The low-energy ion bombardment of GaN produces a Ga-rich surface layer which transforms into a metallic Ga layer at higher bombarding energies. At the same time, the photoemissionspectra around N 1s core levels reveal the presence of both uncoordinated nitrogen and nitrogen interstitials, which we have analyzed in more details by x-rayabsorption measurements at N K edge. We have demonstrated that PES and NEXAFS provide a powerful combination for studying the compositional changes on GaNsurfaces. A mechanism for the relocation and loss of nitrogen during ion bombardment in agreement with some recent experimental and theoretical studies of defect formation in GaN has been proposed.P.N.K.D. is grateful for the financial support of the Australian Research Council

    A Mathematical Study of Glaucoma Using Machine Learning Algorithms for Retina

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    Glaucoma is a category of visual disorders represented by optic nerve neuropathy, a means of gradually declining optic nerve neuropathy. In-ground vision, resulting in sight loss. In this article, a novel retinal therapeutic support vector machine for glaucoma using machine Algorithms for learning is conservative. The algorithm has sufficient pragmatism; the correlation clustering mode is subsequently retained the estimated preparation deterrent on a data set has a 91 percent achievement rate on a data set. Consolidation of 500 realistic resolute and glaucoma retina images; hence, depending on the cluster, the computational advantage of In glaucoma therapy, the overlapping device pedestal on the machine learning algorithm has maximum output

    Two-Hop Routing with Traffic-Differentiation for QoS Guarantee in Wireless Sensor Networks

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    This paper proposes a Traffic-Differentiated Two-Hop Routing protocol for Quality of Service (QoS) in Wireless Sensor Networks (WSNs). It targets WSN applications having different types of data traffic with several priorities. The protocol achieves to increase Packet Reception Ratio (PRR) and reduce end-to-end delay while considering multi-queue priority policy, two-hop neighborhood information, link reliability and power efficiency. The protocol is modular and utilizes effective methods for estimating the link metrics. Numerical results show that the proposed protocol is a feasible solution to addresses QoS service differenti- ation for traffic with different priorities.Comment: 13 page

    Glutathione-S-Transferase and Thiol Stress in patients with acute renal failure

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    Introduction: Tubular damage is common finding in acute renal failure (ARF). Various etiologies have been put forth to explain the tubular damage in ARF, one important mechanism among them is oxidative damage to renal tubules. Several biomolecules including low-molecular weight peptides and enzymes in urine have been proposed as early markers of renal failure. Current study has been undertaken to study the thiol stress and glutathione-S-transferase (GST) levels in ARF patients. Method: 58 ARF patients and 55 healthy controls were selected based on inclusion and exclusion criteria. Serum thiols, GST, malanoldehyde (MDA) and urine thiols were determined by spectrophotometer based methods. Results: Serum thiols and urine thiols were significantly decreased (p<0.0001), and serum GST and MDA levels were significantly increased (p<0.0001) in ARF patients compared to healthy controls. Serum GST and MDA correlated positively in ARF cases (r2 = 0.6938, p<0.0001). Conclusion: There is significant thiol stress and increased lipid peroxidation in ARF patients which leads to tubular cell membrane damage and release of GST into blood stream and into urine. This may be possible mechanism for the increased presence of GST in urine (enzymuria) found in other studie

    Study of Different Algorithms for Face Recognition

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    The importance of utilising biometrics to establish personal authenticity and to detect impostors is growing in the present scenario of global security concern. Development of a biometric system for personal identification, which fulfils the requirements for access control of secured areas and other applications like identity validation for social welfare, crime detection, ATM access, computer security, etc., is felt to be the need of the day [2]. Face recognition has been evolving as a convenient biometric mode for human authentication for more than last two decades. It plays an important role in applications such as video surveillance, human computer interface, and face image database management [1]. A lot of techniques have been applied for different applications. Robustness and reliability becomes more and more important for these applications especially in security systems. Basically Face Recognition is the process through which a person is identified by his facial image. With the help of this technique it is possible to use the facial image of a person to authenticate him into any secure system. Face recognition approaches for still images can be broadly categorized into holistic methods and feature based methods. Holistic methods use the entire raw face image as an input, whereas feature based methods extract local facial features and use their geometric and appearance properties. This work studies the different approaches for a Face Recognition System. The different approaches like PCA, DCT and different types of Wavelets have been studied with the help of Euclidean distance as a classifier and Neural Network as a classifier. The results have been compared for the two database, AMP which contains 975 images of 13 individuals (each person has 75 different images) under various facial expressions and lightning condition with each image being cropped and resized to 64×64 pixels for the simulation and ORL (Olivetti Research Lab) which contains 400 images (each with 112×92 pixels) corresponding to 40 persons in 10 poses each including both male and female. The ORL database image has been resized to 128×128 pixels

    Liquefaction of a Soil Deposit During an Earthquake

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    Large number of cases have been rep or ted where liquefaction has occurred during the earthquake, but only in a few cases, soil report in the zones of liquefaction are available. A wide spread damage because of liquefaction of soil deposit was observed during tile Niigata Earthquake of 1964 in Japan. A very systematic study on soil exploration in the zone of liquefaction was carried out and is well reported. Two sites were selected for the analysis from Niigata in the same area (i) where heavy damage occurred (ii) where no damage occurred. A case study was made using two different methods having different philosophy of analysis for prediction of possibility of liquefaction during an earthquake. The results of different methods are in good agreement with the observed behaviour where liquefaction was observed during the earthquake. But a wide controversy is observed between the two methods where liquefaction did not occur. The paper presents the case study
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