5,287 research outputs found

    Historical problem areas lessons learned

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    Historical problem areas in space transportation propulsion technology are identified in viewgraph form. Problem areas discussed include materials compatibility, contamination, pneumatic/feed system flow instabilities, instabilities in rocket engine combustion and fuel sloshing, exhaust plume interference, composite rocket nozzle failure, and freeze/thaw damage

    Superpartners at LHC and Future Colliders: Predictions from Constrained Compactified M-Theory

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    We study a realistic top-down M-theory compactification with low-scale effective Supersymmetry, consistent with phenomenological constraints. A combination of top-down and generic phenomenological constraints fix the spectrum. The gluino mass is predicted to be about 1.5 TeV. Three and only three superpartner channels, g~g~\tilde{g} \tilde{g}, χ20χ1±\chi_2^0 \chi_1^\pm and χ1+χ1−\chi_1^+ \chi_1^- (where χ20,χ1±\chi_2^0, \chi_1^\pm are Wino-like), are expected to be observable at LHC-14. We also investigate the prospects of finding heavy squarks and Higgsinos at future colliders. Gluino-stop-top, gluino-sbottom-bottom associated production and first generation squark associated production should be observable at a 100 TeV collider, along with direct production of heavy Higgsinos. Within this framework the discovery of a single sparticle is sufficient to determine uniquely the SUSY spectrum, yielding a number of concrete testable predictions for LHC-14 and future colliders, and determination of M3/2M_{3/2} and thereby other fundamental quantities.Comment: 19 pages, 4 figure

    Environmental Services Programs for the Chesapeake Bay

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    Ecosystem Services, Payment for Ecosystem Services, Water Quality, Chesapeake Bay, Environmental Economics and Policy, Resource /Energy Economics and Policy, Q25, Q28, Q53, Q57,

    Bayesian Hierarchical Modelling for Tailoring Metric Thresholds

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    Software is highly contextual. While there are cross-cutting `global' lessons, individual software projects exhibit many `local' properties. This data heterogeneity makes drawing local conclusions from global data dangerous. A key research challenge is to construct locally accurate prediction models that are informed by global characteristics and data volumes. Previous work has tackled this problem using clustering and transfer learning approaches, which identify locally similar characteristics. This paper applies a simpler approach known as Bayesian hierarchical modeling. We show that hierarchical modeling supports cross-project comparisons, while preserving local context. To demonstrate the approach, we conduct a conceptual replication of an existing study on setting software metrics thresholds. Our emerging results show our hierarchical model reduces model prediction error compared to a global approach by up to 50%.Comment: Short paper, published at MSR '18: 15th International Conference on Mining Software Repositories May 28--29, 2018, Gothenburg, Swede

    Monopoles, strings and dark matter

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    We develop a scenario whereby monopoles in a hidden sector yield a decaying dark matter candidate of interest for the PAMELA and FERMI e±e^\pm excesses. The monopoles are not completely hidden due to a very small kinetic mixing and a hidden photon mass. The latter also causes the monopoles and anti-monopoles to be connected by strings. The resulting long-lived objects eventually decay to hidden photons which tend to escape galactic cores before decaying. The mass scales are those of the hidden photon (≈500\approx 500 MeV), the monopole (≈3\approx 3 TeV) and the mixing scale (close to the Planck scale). A gauge coupling in the hidden sector is the only other parameter. This coupling must be strong and this results in light point-like monopoles and light thin strings.Comment: 21 pages, various improvements and additional reference

    Fast and robust two- and three-qubit swapping gates on multi-atomic ensembles in quantum electrodynamic cavity

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    Creation of quantum computer is outstanding fundamental and practical problem. The quantum computer could be used for execution of very complicated tasks which are not solvable with the classical computers. The first prototype of solid state quantum computer was created in 2009 with superconducting qubits. However, it suffers from the decoherent processes and it is desirable to find more practical encoding of qubits with long-lived coherence. It could be single impurity or vacancy centers in solids, but their interaction with electromagnetic radiation is rather weak. So, here, ensembles of atoms were proposed for the qubit encoding by using the dipole blockade mechanism in order to turn multilevel systems in two level ones. But dipole-dipole based blockade introduces an additional decoherence that limits its practical significance. Recently, the collective blockade mechanism has been proposed for the system of three-level atoms by using the different frequency shifts for the Raman transitions between the collective atomic states characterized by a different number of the excited atoms. Here, we propose two qubit gate by using another collective blockade mechanism in the system of two level atoms based on exchange interaction via the virtual photons between the multi-atomic ensembles in the resonator. Also we demonstrate the possibility of three qubit gate (Controlled SWAP gate) using a suppression of the swap-process between two multi-atomic ensembles due to dynamical shift of the atomic levels controlled by the states of photon encoded qubit

    Effects of Macronutrients on Seed Quality and Profitability Analysis of Sunflower Production in Northwest Pakistan

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    Potassium (K) and phosphorus (P) application to sunflower (Helianthus annus L.) reduced cost of production, increased seed oil and protein concentration, yield and net returns on the K and P deficient soils in Northwest Pakistan. Field experiment was conducted at the New Developmental Research Farm of NWFP (North West Frontier Province) Agricultural University Peshawar, Pakistan during summer 2006. The experiment was carried out in a randomized complete block design with split plot arrangements using three replications. Six levels of K (0, 25, 50, 75, 100 and 125 kg ha-1) were kept in main plots while four levels of P (0, 45, 90 and 135 kg ha-1) were kept in sub-plots. Increase in K and P levels enhanced seed oil concentration, on the other hand, increase in P level increased seed protein concentration but increase in K level decreased seed protein concentration. Both oil and protein yields per unit area increased significantly with increase in K and P levels. The increase in oil and protein yields of sunflower was mainly attributed to the improvement in yield components and significant increase in seed yield. The highest net returns of Rs. 25268 (grain yield basis) and Rs. 31274 (oil yield basis) was obtained from those plots that received a combination of 100 kg K + 45 kg P ha-1. Application of 100 kg K ha-1 + 45 kg P ha-1 was therefore, recommended for profitable sunflower production in the agro-climatic conditions in Northwest Pakistan.sunflower, potassium, phosphorus, oil, protein, economic analysis, Northwest Pakistan, Farm Management, International Development, International Relations/Trade, Production Economics, Productivity Analysis,
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