13,024 research outputs found

    Arbitrage opportunities and feedback trading in emissions and energy markets

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    This paper extends Sentana and Wadhwani (SW 1992) model to study the presence of feedback trading in emissions and energy markets and the extent to which such behaviour is linked to the level of arbitrage opportunities. Applying our augmented models to the carbon emission and major energy markets in Europe, we find evidence of feedback trading in coal and electricity markets, but not in carbon market where the institutional investors dominate. This finding is consistent with the notion that institutional investors are less susceptible to pursuing feedback-style investment strategies. In further analysis, our results show that the intensity of feedback trading is significantly related to the level of arbitrage opportunities, and that the significance of such relationship depends on the market regimes

    Water Quality in a Small Tidal Creek: Parker Creek, Virginia

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    Parker Creek is a branched tidal creek located on the Eastern Shore of Virginia. In its southern branch, the creek receives waste inputs from a poultry processing plant. A study has been conducted to determine the effects of these inputs and to formulate a mathematical model of the creek system suitable for water quality planning. The model and field studies show the creek may be divided into two zones, an upstream zone dominated by freshwater flows and waste inputs, and a downstream zone dominated by conditions in adjacent Metomkin Bay. In the upstream zone of the waste-receiving branch, conditions of elevated nutrient and depressed dissolved oxygen concentrations exist. In the downstream zone, conditions are close to natural. For purposes of comparison, surveys were conducted in three similar non-impacted tidal creeks and in Metornkin Bay. From a planning standpoint, the most significant result of these surveys is that violations of minimum dissolved oxygen standards may occur as a natural condition in tidal creeks

    A Water Quality Model of the Elizabeth River

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    Coupled valence and spin state transition in (Pr0.7Sm0.3)0.7Ca0.3CoO3

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    The coupled valence and spin state transition (VSST) taking place in (Pr0.7Sm0.3)0.7Ca0.3CoO3 was investigated by soft x-ray absorption spectroscopy (XAS) experiments carried out at the Pr-M4,5, Co-L2,3, and O-1s edges. This VSST is found to be composed of a sharp Pr/Co valence and Co spin state transition centered at T*=89.3 K, followed by a smoother Co spin-state evolution at higher temperatures. At T < T*, we found that the praseodymium displays a mixed valence Pr3+/Pr4+ with about 0.13 Pr4+/f.u., while all the Co3+ is in the low-spin (LS) state. At T around T*, the sharp valence transition converts all the Pr4+ to Pr3+ with a corresponding Co3+ to Co4+ compensation. This is accompanied by an equally sharp spin state transition of the Co3+ from the low to an incoherent mixture of low and high spin (HS) states. An involvement of the intermediate spin (IS) state can be discarded for the Co3+. While above T* and at high temperatures the system shares rather similar properties as Sr-doped LaCoO3, at low temperatures it behaves much more like EuCoO3 with its highly stable LS configuration for the Co3+. Apparently, the mechanism responsible for the formation of Pr4+ at low temperatures also helps to stabilize the Co3+ in the LS configuration despite the presence of Co4+ ions. We also found out that that the Co4+ is in an IS state over the entire temperature range investigated in this study (10-290 K). The presence of Co3+ HS and Co4+ IS at elevated temperatures facilitates the conductivity of the material.Comment: 19 pages, 7 figures, Accepted in PR

    The first operation and results of the Chung-Li VHF radar

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    The Chung-Li Very High Frequency (VHF) radar is used in the dual-mode operations, applying Doppler beam-swinging as well as the spaced-antenna-drift method. The design of the VHF radar is examined. Results of performance tests are discussed

    Quasi-Monte Carlo methods for high-dimensional integration: the standard (weighted Hilbert space) setting and beyond

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    This paper is a contemporary review of quasi-Monte Carlo (QMC) methods, that is, equal-weight rules for the approximate evaluation of high-dimensional integrals over the unit cube [0,1]s[0,1]^s. It first introduces the by-now standard setting of weighted Hilbert spaces of functions with square-integrable mixed first derivatives, and then indicates alternative settings, such as non-Hilbert spaces, that can sometimes be more suitable. Original contributions include the extension of the fast component-by-component (CBC) construction of lattice rules that achieve the optimal convergence order (a rate of almost 1/N1/N, where NN is the number of points, independently of dimension) to so-called “product and order dependent†(POD) weights, as seen in some recent applications. Although the paper has a strong focus on lattice rules, the function space settings are applicable to all QMC methods. Furthermore, the error analysis and construction of lattice rules can be adapted to polynomial lattice rules from the family of digital nets. doi:10.1017/S144618111200007

    Phase and group velocity tracing analysis of projected wave packet motion along oblique radar beams ? qualitative analysis of QP echoes

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    International audienceThe wave packets of atmospheric gravity waves were numerically generated, with a given characteristic wave period, horizontal wave length and projection mean wind along the horizontal wave vector. Their projection phase and group velocities along the oblique radar beam (vpr and vgr), with different zenith angle ? and azimuth angle ?, were analyzed by the method of phase- and group-velocity tracing. The results were consistent with the theoretical calculations derived by the dispersion relation, reconfirming the accuracy of the method of analysis. The RTI plot of the numerical wave packets were similar to the striation patterns of the QP echoes from the FAI irregularity region. We propose that the striation range rate of the QP echo is equal to the radial phase velocity vpr, and the slope of the energy line across the neighboring striations is equal to the radial group velocity vgr of the wave packet; the horizontal distance between two neighboring striations is equal to the characteristic wave period ?. Then, one can inversely calculate all the properties of the gravity wave responsible for the appearance of the QP echoes. We found that the possibility of some QP echoes being generated by the gravity waves originated from lower altitudes cannot be ruled out
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