74,888 research outputs found

    A study on Electron Beam Welding of Stainless steel (03X12H10MTPY) with Russian copper alloy

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    Modern age demand for flexible design and high quality structures. Different properties are essential for different parts and use of dissimilar metals joints gives possibilities of flexible design and products by using each material efficiently. EBW is one of the most widely used application in industries for joining dissimilar materials .The advantages of EBW welding is its high energy density, high depth to width ratio, low HAZ and result in very strong weld and low residual stress .The quality of weld depend upon the parameter accelerating voltage, beam current, focus current, welding speed, beam shifts and vacuum levels. The beam shift, focus current and vacuum level are fixed parameters .The primary objective of the project is to optimizing the parameter to obtain best quality weld based on Taguchi L9 array. Micro-indentation hardness and Electron spectroscopy is also carried out in selected welding sets to study the joint characteristics. It is observed that the optimum parameter levels for 3mm penetration in both parent metal are Accelerating voltage 50KV, beam current 38mA, welding speed 1 m/min

    Review of optimal design of composite structures under uncertainty

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    This study represents optimization of hollow circular, rectangular and airfoil composite beam by using sub problem approximation method in ANSYS. A three dimensional static analysis of large displacement type has been carried out for hollow circular, rectangular and airfoil composite beams. Weight of beam was objective function, material parameter, geometrical, ply thickness, ply angles and load. In order to validate the results, one loop of simulation is benchmarked from results in literature. Ultimately, best set of optimized design variable is proposed to reduce weight under static loading condition

    Elm Farm Organic Research Centre Bulletin 83 April 2006

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    Regular bulleting with technical updates from Organic Advisory Service Issue contains: Testing for Tolerance - a pragmatic view GM Debate Vaccination nation - to jab or not to jab Future shape of OCIS Evolutionary wheat makes the grade? NIAB tracks health of organic cereal seed Stopping erosion of soil quality - the organic way Care needed to halt butterfly collapse Aspects of poultry behaviour: How free range is free range? On choosing an organic wheat A local education challenge New Wakelyns Science Building Organic vegetable market growt

    A Modified Approch Audio Stagnography Based On Technique LSB Coding

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    Information security is becoming very important part of our life now-a-days. Information hiding is the fundamental of information security. Information hiding can be achieved by steganography as well. This paper presents a modified method of audio stegnography. Audio steganography is the technique of hiding secret information in the audio files. nbspWe have presented a high capacity and high stego-signal quality audio steganography scheme based on samples comparison in DWT domain where selected coefficient of a segment are compared with pre determined threshold value T and based on comparison bits are embedded. The strength of our algorithm is depend on the segment size andnbsp their strength are enabled the algorithm to achieve very high embedding capacity for different data type that can reach up to 25%nbsp from the input audio file size with lest of 35 dBnbsp SNR for the output stego signal. Further we have tabulated the result and the conclusion is made on the basis of the obtained results

    New Examples of Flux Vacua

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    Type IIB toroidal orientifolds are among the earliest examples of flux vacua. By applying T-duality, we construct the first examples of massive IIA flux vacua with Minkowski space-times, along with new examples of type IIA flux vacua. The backgrounds are surprisingly simple with no four-form flux at all. They serve as illustrations of the ingredients needed to build type IIA and massive IIA solutions with scale separation. To check that these backgrounds are actually solutions, we formulate the complete set of type II supergravity equations of motion in a very useful form that treats the R-R fields democratically.Comment: 38 pages, LaTeX; references updated; additional minor comments added; published versio

    Limits of minimal models and continuous orbifolds

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    The lambda=0 't Hooft limit of the 2d W_N minimal models is shown to be equivalent to the singlet sector of a free boson theory, thus paralleling exactly the structure of the free theory in the Klebanov-Polyakov proposal. In 2d, the singlet sector does not describe a consistent theory by itself since the corresponding partition function is not modular invariant. However, it can be interpreted as the untwisted sector of a continuous orbifold, and this point of view suggests that it can be made consistent by adding in the appropriate twisted sectors. We show that these twisted sectors account for the `light states' that were not included in the original 't Hooft limit. We also show that, for the Virasoro minimal models (N=2), the twisted sector of our orbifold agrees precisely with the limit theory of Runkel & Watts. In particular, this implies that our construction satisfies crossing symmetry.Comment: 33 pages; v2: minor improvements and references added, published versio

    Large N=4 Holography

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    The class of 2d minimal model CFTs with higher spin AdS3 duals is extended to theories with large N=4 superconformal symmetry. We construct a higher spin theory based on the global D(2,1|alpha) superalgebra, and propose a large N family of cosets as a dual CFT description. We also indicate how a non-abelian version of this Vasiliev higher spin theory might give an alternative description of IIB string theory on an AdS3 x S3 x S3 x S1 background.Comment: 41 pages, LaTe

    N=1 extension of minimal model holography

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    The CFT dual of the higher spin theory with minimal N = 1 spectrum is determined. Unlike previous examples of minimal model holography, there is no free parameter beyond the central charge, and the CFT can be described in terms of a non-diagonal modular invariant of the bosonic theory at the special value of the 't Hooft parameter lambda=1/2. As evidence in favour of the duality we show that the symmetry algebras as well as the partition functions agree between the two descriptions.Comment: 28 page

    The Large N 't Hooft Limit of Kazama-Suzuki Model

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    We consider N=2 Kazama-Suzuki model on CP^N=SU(N+1)/SU(N)xU(1). It is known that the N=2 current algebra for the supersymmetric WZW model, at level k, is a nonlinear algebra. The N=2 W_3 algebra corresponding to N=2 was recovered from the generalized GKO coset construction previously. For N=4, we construct one of the higher spin currents, in N=2 W_5 algebra, with spins (2, 5/2, 5/2, 3). The self-coupling constant in the operator product expansion of this current and itself depends on N as well as k explicitly. We also observe a new higher spin primary current of spins (3, 7/2, 7/2, 4). From the behaviors of N=2, 4 cases, we expect the operator product expansion of the lowest higher spin current and itself in N=2 W_{N+1} algebra. By taking the large (N, k) limit on the various operator product expansions in components, we reproduce, at the linear order, the corresponding operator product expansions in N=2 classical W_{\infty}^{cl}[\lambda] algebra which is the asymptotic symmetry of the higher spin AdS_3 supergravity found recently.Comment: 44 pages; the two typos in the first paragraph of page 23 corrected and to appear in JHE
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