3,382 research outputs found

    Flat Currents in the Classical AdS_5 x S^5 Pure Spinor Superstring

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    It is proven that the classical pure spinor superstring in an AdS_5 x S^5 background has a flat current depending on a continuous parameter. This generalizes the recent result of Bena, et al. for the classical Green-Schwarz superstring.Comment: 10 pages, 1 figure, harvma

    Remarks on Screening in a Gauge-Invariant Formalism

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    In this paper we display a direct and physically attractive derivation of the screening contribution to the interaction potential in the Chiral Schwinger model and generalized Maxwell-Chern-Simons gauge theory. It is shown that these results emerge naturally when a correct separation between gauge-invariant and gauge degrees of freedom is made. Explicit expressions for gauge-invariant fields are found.Comment: 13 pages, 1 figure, to appear in PR

    Defect Signal Analysis For Nondestructive Testing Assesment

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    For fast assessment of defects in conductive materials, Eddy current testing is a most widely non-destructive testing (NDT) evaluation methods utilized in industry, especially in oil and gas, aircraft, nuclear and coating industries. Experimental studies of eddy current testing have emerged as an important approach alongside numerical modelling. This paper focus on investigating the defect signal characteristics of carbon steel pipe weld coating inspection using different frequency eddy current testing. The optimum frequency of carbon steel pipe weld coating is verified. Tests have been conducted utilizing positive and negative scanning method with frequency between 10 kHz to 100 kHz. Artificial defect use of this test is the horizontal affected zone (HAZ), centre line and transverse crack. Experimental results showed the frequency can be impression to the amplitude and phase angle eddy current testing signal. The optimum frequency for carbon steel weld plate is 100 kHz

    Determination of Critical Overload Transmission Line Using Novel Maximum Power Line Stability Index

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    Recent years, a larger number of DG’s are being employed especially at the critical load ends to reduce the burden on the main feeder. One of the benefits of employing DG that it improves the system voltage stability even with load increment. The primary focus of this paper rests on creating a novel line voltage stability index. The line stability index approach is proposed based on Thevenin theory to gauge the DG level impact on transmission line. Transmission issues due to the overloading of lines in high DG penetration areas during the outage scenarios taking place earlier. The rationale for the proposed strategy will be experimented on a standard IEEE 30 bus test system compared with other line voltage stability indexes

    The Impact of Academic Satisfaction as a Mediator on International Conferences

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    Scientists have lately discovered that the quality of services has a significant influence on academic satisfaction and academic loyalty. Universities in Erbil are competing attract academics by conducting international conferences. The purpose of this study is to evaluate the service quality in international conferences. A statistical analysis was provided based on data collected from 150 responses from academics at Cihan University-Erbil and other universities in the region. A structured questionnaire was conducted by the respondents in order to analyze their general expectations on conference services and the actual service performance they perceived with the conference. The study also assessed the impact of respondents’ past experiences on their expectations. The findings of this study show that we have positive effect between the total effect of (SQ) the independent variable on (CI) the dependent variable is highly significant with (t = 6.02, p< 0.05), also the effect of the mediator variable (AS) was significant with (t = 7.01, p< 0.05), and finally both the independent variable and the mediator variable (SQ) and (AS) have a significant effect on the dependent variable (CI). We found that the meditation effect was partial but not complete effect

    Signature of the interaction between dark energy and dark matter in observations

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    We investigate the effect of an interaction between dark energy and dark matter upon the dynamics of galaxy clusters. This effect is computed through the Layser-Irvine equation, which describes how an astrophysical system reaches virial equilibrium and was modified to include the dark interactions. Using observational data from almost 100 purportedly relaxed galaxy clusters we put constraints on the strength of the couplings in the dark sector. We compare our results with those from other observations and find that a positive (in the sense of energy flow from dark energy to dark matter) non vanishing interaction is consistent with the data within several standard deviations.Comment: 13 pages, 3 figures; matches PRD published versio

    Hybrid of Eddy Current Probe Based on Permanent Magnet and GMR Sensor

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    The eddy current testing (ECT) is used to inspect a material to determine its properties without destroying its utility. The applications include detection of flaws in aircrafts, pipeline, etc. An ECT is a weak sensitivity to a subsurface defect. Applications of giant magnetic sensors (GMR) are increasingly applied to the measurement of weak magnetic fields related to the currents they cause. In this paper, GMR sensor with magnet bar (permanent) is utilized. The proposed probe system is utilized to study the impact of the width and depth defect on the signal of eddy current testing. The maximum depth of flaw in a mild steel can be revealed by using this probe. The graph of the difference between the peak amplitude and the penetration depth of each slot of a different width of the two bands of mild steel shows the increase of the signal for each slot and flat above 3mm. The experimental result proves the inability of a PMGMR probe to detect a defect at a depth of 3mm on a surface defect

    Non-Z2\mathbb{Z}_{2} symmetric braneworlds in scalar tensorial gravity

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    We obtain, via the Gauss-Codazzi formalism, the expression of the effective Einstein-Brans-Dicke projected equations in a non-Z2\mathbb{Z}_{2} symmetric braneworld scenario which presents hybrid compactification. It is shown that the functional form of such equations resembles the one in the Einstein's case, except by the fact that they bring extra informations in the context of exotic compactifications.Comment: 12 pages, LATEX file, no figures. Accepted for publication in the European Physical Journal

    Gas Turbine Configuration for Improving the performance of Combined Cycle Power Plant

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    AbstractThe thermodynamic analysis of combined cycle gas turbine with effect different configuration for gas turbine are presented and discussed in this paper. The effects of ambient temperature and compression ratio have been proposed to select optimum configuration for gas turbine and its effect on CCGT performance. The analysis performance code has been performed used the MATLAB software. The simulating code for gas turbine configuration results show that the simple gas turbine configuration is more suitable with regards to power output, but the regenerative gas turbine configuration has higher efficiency with effect ambient temperature. The simple gas turbine configuration has higher power output with effect the compression ratio, while the regenerative gas turbine configuration has higher efficiency with effect lower compression ratio, therefore the variation of total power output is insignificance at lower compression ratio. The extensive modelling performed in this study reveals that, the ambient temperature and compression ratios are strongly influence on the performance of combined cycle, a higher overall efficiency can be achieved for combined cycle with add regenerative to topping cycle
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