7,187 research outputs found

    Evaluating the demand for aquaculture insurance: An investigation of fish farmers' willingness to pay in central coastal areas in China

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    Despite the remarkable development in its fishery sector, the penetration rate of fishery insurance in China is considerably low. This paper examines the key factors that contribute to the poor performance of fishery insurance, in particular aquaculture insurance, in China. The double-bounded dichotomous choice contingent valuation method (DB DCCVM) is used to investigate fish farmers’ willingness to pay (WTP) for an insurance program, based on a survey of 1280 fish farmers in three coastal cities in China. The results indicate that fish farmers’ decisions on adoption of an insurance scheme depend on various factors, among which magnitude of loss, fish farmers’ awareness toward insurance and their education all have a positive impact. However, income and farming years are more likely to have a negative effect. In addition, the mean WTP for aquaculture insurance is estimated to be CNY 579 (US$ 90.05) 2 per household, which is equivalent to 1.5% of fish farmers' mean annual income. These results provide several policy implications for not only the Chinese government but also researchers as well as insurance companies

    Superconductivity in Ti-doped Iron-Arsenide Compound Sr4Cr0.8Ti1.2O6Fe2As2

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    Superconductivity was achieved in Ti-doped iron-arsenide compound Sr4Cr0.8Ti1.2O6Fe2As2 (abbreviated as Cr-FeAs-42622). The x-ray diffraction measurement shows that this material has a layered structure with the space group of \emph{P4/nmm}, and with the lattice constants a = b = 3.9003 A and c = 15.8376 A. Clear diamagnetic signals in ac susceptibility data and zero-resistance in resistivity data were detected at about 6 K, confirming the occurrence of bulk superconductivity. Meanwhile we observed a superconducting transition in the resistive data with the onset transition temperature at 29.2 K, which may be induced by the nonuniform distribution of the Cr/Ti content in the FeAs-42622 phase, or due to some other minority phase.Comment: 3 pages, 3 figure

    Pressure Effect on the superconducting properties of LaO_{1-x}F_{x}FeAs(x=0.11) superconductor

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    Diamagnetic susceptibility measurements under high hydrostatic pressure (up to 1.03 GPa) were carried out on the newly discovered Fe-based superconductor LaO_{1-x}F_{x}FeAs(x=0.11). The transition temperature T_c, defined as the point at the maximum slope of superconducting transition, was enhanced almost linearly by hydrostatic pressure, yielding a dT_c/dP of about 1.2 K/GPa. Differential diamagnetic susceptibility curves indicate that the underlying superconducting state is complicated. It is suggested that pressure plays an important role on pushing low T_c superconducting phase toward the main (optimal) superconducting phase.Comment: 7 pages, 4 figure

    Data-Driven Dynamic Modeling of Coupled Thermal and Electric Outputs of Microturbines

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    Microturbines (MTs) are among the most successfully commercialized distributed energy resources, especially when they are used for combined heat and power generation. However, the interrelated thermal and electrical system dynamic behaviors have not been fully investigated. This is technically challenging due to the complex thermo-fluid-mechanical energy conversion processes, which introduce multiple time-scale dynamics and strong nonlinearity into the analysis. To tackle this problem, this paper proposes a simplified model which can predict the coupled thermal and electric output dynamics of MTs. Considering the time-scale difference of various dynamic processes occurring within MTs, the electromechanical subsystem is treated as a fast quasi-linear process, while the thermo-mechanical subsystem is treated as a slow process with high nonlinearity. A three-stage subspace identification method is utilized to capture the dominant dynamics and predict the electric power output. For the thermo-mechanical process, a radial basis function model trained by the particle swarm optimization method is employed to handle the strong nonlinear characteristics. Experimental tests on a Capstone C30 MT show that the proposed modeling method can well capture the system dynamics, and produce a good prediction of the coupled thermal and electric outputs in various operating modes

    Advances in the functional study of glutamine synthetase in plant abiotic stress tolerance response

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    Plant glutamine synthetase (GS, EC6.3.1.2) catalyzes the synthesis of glutamine from glutamate and ammonium ions and acts as a key enzyme in the nitrogen metabolic pathway in organisms. Nitrogen is an essential element for plant growth and development and plays an important role in crop yield and quality formation. Therefore, GS is crucial in many physiological processes in plants. Currently, nitrogen regulation by GS in plants is well-studied in terms of its effect on plant growth and development. This article reviews the regulatory role of plant GS and its molecular mechanism in mitigating stress injury, such as low or high temperature, salinity, drought and oxidation. The function of plant GS in stress tolerance response is focused. The review aims to provide a reference for the utilization of plant GS in crop stress tolerance breeding

    CP-violating asymmetry in Λ→pπ\Lambda\to p\pi in the Skyrme model

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    We study the CP-violating asymmetry in nonleptonic decay Λ→pπ\Lambda\to p\pi. By employing the Skyrme model to calculate this decay amplitude contributed by the gluonic diploe operator, we find a possible large CP-violating asymmetry could be expected, which is consistent with the previous study.Comment: LaTeX file, To appear in J Phys G: Nucl Phys and Part Phy

    Angular dependence of resistivity in the superconducting state of NdFeAsO0.82_{0.82}F0.18_{0.18} single crystals

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    We report the results of angle dependent resistivity of NdFeAsO0.82_{0.82}F0.18_{0.18} single crystals in the superconducting state. By doing the scaling of resistivity within the frame of the anisotropic Ginzburg-Landau theory, it is found that the angle dependent resistivity measured under different magnetic fields at a certain temperature can be collapsed onto one curve. As a scaling parameter, the anisotropy Γ\Gamma can be determined for different temperatures. It is found that Γ(T)\Gamma(T) increases slowly with decreasing temperature, varying from Γ≃\Gamma \simeq 5.48 at T=50 K to Γ≃\Gamma \simeq 6.24 at T=44 K. This temperature dependence can be understood within the picture of multi-band superconductivity.Comment: 7 pages, 4 figure

    Optimal and Low Complexity Control of SOA-Based Optical Switching with Particle Swarm Optimisation

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    We propose a reliable, low-complexity particle swarm optimisation (PSO) approach to control semiconductor optical amplifier (SOA)-based s witches. We experimentally demonstrate less than 610 ps off-on switching (settling) time and less than 2.2% overshoot with 20x lower sampling rate and 8x reduced DAC resolution
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