9,819 research outputs found

    Pricing and low-carbon investment decisions in an emission dependent supply chain under a carbon labelling scheme

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    A low-carbon policy attracts the interests of businesses, consumers, and policy makers. The purpose of this paper is to investigate how a carbon labelling scheme could be integrated into operational decision-making for manufacturers and retailers. Three game theoretic models of a supply chain with one manufacturer and one retailer are built to investigate a manufacturer and retailer’s pricing and investment decision for products with different initial carbon footprints considering consumer environmental awareness. Through a systematic comparison and numerical analysis, the results show that a carbon labelling scheme can significantly reduce the overall carbon emission supply chain and have an initially negative impact on the manufacturer and retailer’s profits. However, in the medium–long run, manufacturers and retailers could yet achieve profitability through continuously investing in low-carbon technology

    Electronic structure of Fe1.04(Te0.66Se0.34)

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    We report the electronic structure of the iron-chalcogenide superconductor, Fe1.04(Te0.66Se0.34), obtained with high resolution angle-resolved photoemission spectroscopy and density functional calculations. In photoemission measurements, various photon energies and polarizations are exploited to study the Fermi surface topology and symmetry properties of the bands. The measured band structure and their symmetry characters qualitatively agree with our density function theory calculations of Fe(Te0.66Se0.34), although the band structure is renormalized by about a factor of three. We find that the electronic structures of this iron-chalcogenides and the iron-pnictides have many aspects in common, however, significant differences exist near the Gamma-point. For Fe1.04(Te0.66Se0.34), there are clearly separated three bands with distinct even or odd symmetry that cross the Fermi energy (EF) near the zone center, which contribute to three hole-like Fermi surfaces. Especially, both experiments and calculations show a hole-like elliptical Fermi surface at the zone center. Moreover, no sign of spin density wave was observed in the electronic structure and susceptibility measurements of this compound.Comment: 7 pages, 9 figures. submitted to PRB on November 15, 2009, and accepted on January 6, 201

    Upper critical fields and thermally-activated transport of Nd(O_0.7F_0.3)FeAs single crystal

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    We present measurements of the resistivity and the upper critical field H_c2 of Nd(O_0.7F_0.3)FeAs single crystals in strong DC and pulsed magnetic fields up to 45 T and 60 T, respectively. We found that the field scale of H_c2 is comparable to ~100 T of high T_c cuprates. H_c2(T) parallel to the c-axis exhibits a pronounced upward curvature similar to what was extracted from earlier measurements on polycrystalline samples. Thus this behavior is indeed an intrinsic feature of oxypnictides, rather than manifestation of vortex lattice melting or granularity. The orientational dependence of H_c2 shows deviations from the one-band Ginzburg-Landau scaling. The mass anisotropy decreases as T decreases, from 9.2 at 44K to 5 at 34K. Spin dependent magnetoresistance and nonlinearities in the Hall coefficient suggest contribution to the conductivity from electron-electron interactions modified by disorder reminiscent that of diluted magnetic semiconductors. The Ohmic resistivity measured below T_c but above the irreversibility field exhibits a clear Arrhenius thermally activated behavior over 4-5 decades. The activation energy has very different field dependencies for H||ab and H\perp ab. We discuss to what extent different pairing scenarios can manifest themselves in the observed behavior of H_{c2}, using the two-band model of superconductivity. The results indicate the importance of paramagnetic effects on H_c2(T),which may significantly reduce H_c2(0) as compared toH_c2(0)~200-300 T based on extrapolations of H_c2(T) near T_c down to low temperatures.Comment: 11 pages, 16 figure

    Graphite Nanoeraser

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    We present here a method for cleaning intermediate-size (5~50nm) contamination from highly oriented pyrolytic graphite. Electron beam deposition causes a continuous increase of carbonaceous material on graphene and graphite surfaces, which is difficult to remove by conventional techniques. Direct mechanical wiping using a graphite nanoeraser is observed to drastically reduce the amount of contamination. After the mechanical removal of contamination, the graphite surfaces were able to self-retract after shearing, indicating that van der Waals contact bonding is restored. Since contact bonding provides an indication of a level of cleanliness normally only attainable in a high-quality clean-room, we discuss potential applications in preparation of ultraclean surfaces.Comment: 10 pages, two figure

    Distribution of Spectral Lags in Gamma Ray Bursts

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    Using the data acquired in the Time To Spill (TTS) mode for long gamma-ray bursts (GRBs) collected by the Burst and Transient Source Experiment on board the Compton Gamma Ray Observatory (BATSE/CGRO), we have carefully measured spectral lags in time between the low (25-55 keV) and high (110-320 keV) energy bands of individual pulses contained in 64 multi-peak GRBs. We find that the temporal lead by higher-energy gamma-ray photons (i.e., positive lags) is the norm in this selected sample set of long GRBs. While relatively few in number, some pulses of several long GRBs do show negative lags. This distribution of spectral lags in long GRBs is in contrast to that in short GRBs. This apparent difference poses challenges and constraints on the physical mechanism(s) of producing long and short GRBs. The relation between the pulse peak count rates and the spectral lags is also examined. Observationally, there seems to be no clear evidence for systematic spectral lag-luminosity connection for pulses within a given long GRB.Comment: 20 pages, 4 figure

    Research on the Piston with Damping Hole and Pressure Recess of Axial Piston Motor

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    Based on the principle of hydrostatic bearing, in this study, several novel kinds of pistons were designed out, and the mathematic model of hydrostatic bearing on piston was established and analyzed. It was also found that, the diameter of damping hole and the width of pressure recess had impact on the radial load capacity of piston, the overall efficiency of axial piston motor, and the friction and wear capacity of piston. Results from tests shown that in the case of the pressure difference of 10MPa to 22MPa and the different speed of 500rpm to 2000rpm, the overall efficiency of axial piston motor could be improved by 0.1%-0.6%, compared to the ordinary piston. On the other hand, the wear scar of the piston modified was circular, and the one of the ordinary piston was longitudinal and deep, which shown that the piston modified could improve the wear capacity

    Effect of Cement Stabilization on Shear Strength Parameters of Soft Soils on Agricultural Road

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    Agricultural roads play a crucial role in facilitating transportation in agricultural regions, including horticulture, smallholder farms and plantations. However, the agricultural roads in Sungai Balang, Muar face challenges due to the poor condition of the soft soil. Soft soil is characterized by low shear strength, high compressibility and large settlements, making it unsuitable for efficient road infrastructure. To address these issues, cement stabilization has been proposed in this study as a potential solution to improve the soft soil on agricultural roads in the paddy field area of Sungai Balang. The objectives of this study are to identify the classification of the soft soil on agricultural roads in Sungai Balang through grain size analysis, moisture content test, specific gravity test, Atterberg limit test and standard proctor compaction test and to determine the effectiveness of cement stabilization through direct shear test. The direct shear test was carried out to evaluate the shear strength parameters of the soil on the agricultural roads before and after the addition of different percentages of cement (5%, 10% and 15% by dry weight of the soft soil). The results of soil classification showed that the soft soil on agricultural roads in Sungai Balang was classified as MH, which was silty soil with high plasticity. Besides, the results of direct shear test indicated that the 15% cement specimen achieved the optimum percentages compared to the others. The friction angle of the 15% cement specimen had increased from 28o to 43o and the cohesion had increased from 28.33 kPa to 85.00 kPa compared to the untreated soil samples. By studying the effects of different percentages of cement on soil settlements, the research provides insights into the performance and suitability of cement stabilization in enhancing the stability and strength of soft soils on agricultural roads
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