212 research outputs found

    LEACH Based Method for Prolong the Network Life

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    In this paper, it focuses at the communication protocols, that can have important effect on the whole energy dissipation of these types of networks. Depend on the observations that the conventional protocols of direct transmission, multi-hop routing, minimum-transmission-energy, and static clustering cannot be better for the sensor networks, it suggest the LEACH (Low-Energy Adaptive Clustering Hierarchy), to equally share the load of energy in the network among the sensors. MANET has a dynamic type of topology because of the movement of portable terminals in the network. These types of mobile terminals are battery operated and need battery resources for the purpose of communication also these types of resources are very limited. This protocol provides help to decrease the power consumption of terminals and also extends the life of battery to enhance the life time of network. This paper, point out on the energy efficient routing protocol that is LEACH (Low Energy Adaptive Clustering Hierarchy) is discovered, by the use of this protocol the performance of network is improved by decreasing the consumption of power of mobile terminals in the network

    Clustering Based Routing Protocol LEACH and Its’ Variants: A Review

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    In clustering technique LEACH is refer as an important protocol of the hierarchical routing protocols that is applied to decrease the loss of energy in disseminating and collecting. This paper is related with definite hierarchical routing protocols that are generated from the LEACH. This paper presents some main points of few problems and drawbacks in LEACH and explained how to recover via the sections of LEACH. In this paper various properties are compared, also accomplishment and problems of all hierarchical routing protocols are compared. In this it is also discussed regarding the LEACH and its several protocols that are depend on hierarchal routing protocol

    Note On Linear Stability of Steady Hydromagetic Flows of An Incompressible Fluid

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    In the present paper energy method is used to obtain two sufficient conditions for linear stability of steady hydrodynamical flows. The idea of the method is to construct a small three-dimensional perturbations and formulate the stability criteria for the steady magnetohydrodynamic flows of an ideal incompressible.The stability conditions so obtained ensure non existence of perturbations which grow with time faster than linealy

    Shrinking limits of silicon MOSFET's: Numerical study of 10-nm-scale devices

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    We have performed numerical modeling of dual-gate ballistic n-MOSFET's with channel length of the order of 10 nm, including the effects of quantum tunneling along the channel and through the gate oxide. Our analysis includes a self-consistent solution of the full (two-dimensional) electrostatic problem, with account of electric field penetration into the heavily-doped electrodes. The results show that transistors with channel length as small as 8 nm can exhibit either a transconductance up to 4,000 mS/mm or gate modulation of current by more than 8 orders of magnitude, depending on the gate oxide thickness. These characteristics make the devices satisfactory for logic and memory applications, respectively, though their gate threshold voltage is rather sensitive to nanometer-scale variations in the channel length.Comment: 8 pages, 10 figures. Submitted to Special Issue of Superlattices and Microstructures: Third NASA Workshop on Device Modeling, August 199

    Wormhole with varying cosmological constant

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    It has been suggested that the cosmological constant is a variable dynamical quantity. A class of solution has been presented for the spherically symmetric space time describing wormholes by assuming the erstwhile cosmological constant Λ\Lambda to be a space variable scalar, viz., Λ\Lambda = Λ(r)\Lambda (r) . It is shown that the Averaged Null Energy Condition (ANEC) violating exotic matter can be made arbitrarily small.Comment: 8 pages, 2 figures, Accepted in Gen. Rel. Gra

    Can electro-magnetic field, anisotropic source and varying Λ\Lambda be sufficient to produce wormhole spacetime ?

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    It is well known that solutions of general relativity which allow for traversable wormholes require the existence of exotic matter (matter that violates weak or null energy conditions [WEC or NEC]). In this article, we provide a class of exact solution for Einstein-Maxwell field equations describing wormholes assuming the erstwhile cosmological term Λ\Lambda to be space variable, viz., Λ=Λ(r)\Lambda = \Lambda (r). The source considered here not only a matter entirely but a sum of matters i.e. anisotropic matter distribution, electromagnetic field and cosmological constant whose effective parts obey all energy conditions out side the wormhole throat. Here violation of energy conditions can be compensated by varying cosmological constant. The important feature of this article is that one can get wormhole structure, at least theoretically, comprising with physically acceptable matters.Comment: Some changes have been mad

    Expression level of CCR5 chemokine receptor on blood CD4+ and CD8+ T-cells plays an important role in the Ascending Aortic Aneurysm pathophysiology.

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    Background and aim: The CC chemokine receptor 5 (CCR5) is involved in the migration of circulating NK and Th1 cells towards inflammatory sites. CCR5 expression has also been demonstrated on endothelial cells, aortic smooth muscle cells and implicated in the development of abdominal aortic aneurysm. Thoracic aortic aneurysm (TAA) is a lethal disease burdened by complications such as aortic dissection/rupture. The risk of these acute events has been related to the severity of aortic enlargement. The aim of our study is to investigate a possible role of CCR5 expression on peripheral blood CD4+ and CD8+ T-lymphocytes in the pathogenesis of TAA. Methods: We have studied 14 patients (8 female, 6 male) with mean age of 67.35?7.70, undergoing isolated aortic valve replacement (AVR) and/or TAA surgery. Preoperatively, venous blood samples were obtained. A three colors flow cytometric analysis was performed by appropriate combinations of monoclonal antibodies directed against the following surface molecules: CD3, CD4, CD8, CCR5. Data are expressed in terms of percentage of positivity. Maximal aortic diameter (MAD) was determined by transesophageal echocardiography. For each patient we calculated the aortic size index (ASI), defined as MAD/BSA (mm/m2). Results: Aortic index was 21.52?3.14 mm/m2. Nine patients underwent isolated AVR (group 1) and five patients underwent TAA surgery (group 2). The percentage of CCR5+ on CD4+ was significantly higher in group 2 (17.03?3.08 vs 13.03?2.72, p=0.0269). A trend towards a higher percentage of CCR5+ on CD8+ was observed in group 2 (22.74?8,39 vs 16.26?3.75, p=0.0653). A significant correlation between aortic index and the percentage of CD4+ and CD8+ T-cells expressing CCR5 was observed (p=0.048, R2=0.287 and p=0.0067, R2=0.471 respectively). Conclusions: The correlation between the percentage of CD4+ and CD8+ T-cells expressing CCR5 and aortic index suggests the role of a T-cell immune-mediated cytotoxic mechanism in the progression of TAA disease

    Observation of Orbitally Excited B_s Mesons

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    We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let

    Measurement of the ttbar Production Cross Section in ppbar collisions at sqrt s = 1.96 TeV in the All Hadronic Decay Mode

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    We report a measurement of the ttbar production cross section using the CDF-II detector at the Fermilab Tevatron. The analysis is performed using 311 pb-1 of ppbar collisions at sqrt(s)=1.96 TeV. The data consist of events selected with six or more hadronic jets with additional kinematic requirements. At least one of these jets must be identified as a b-quark jet by the reconstruction of a secondary vertex. The cross section is measured to be sigma(tbart)=7.5+-2.1(stat.)+3.3-2.2(syst.)+0.5-0.4(lumi.) pb, which is consistent with the standard model prediction.Comment: By CDF collaboratio

    Search for chargino-neutralino production in ppbar collisions at sqrt(s) = 1.96 TeV

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    We present the results of a search for associated production of the chargino and neutralino supersymmetric particles using up to 1.1 fb-1 of integrated luminosity collected by the CDF II experiment at the Tevatron ppbar collider at a center-of-mass energy of 1.96 TeV. The search is conducted by analyzing events with a large transverse momentum imbalance and either three charged leptons or two charged leptons of the same electric charge. The numbers of observed events are found to be consistent with standard model expectations. Upper limits on the production cross section are derived in different theoretical models. In one of these models a lower limit on the mass of the chargino is set at 129 GeV/c^2 at the 95% confidence level.Comment: To be submitted to Phys.Rev.Let
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