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[en] This article extends the traditional electricity peak-load pricing model to include transmission costs. In the context of a two-node, two-technology electric power system, where suppliers face inelastic demand, we show that when the marginal plant is located at the energy-importing center, generators located away from that center should pay the marginal capacity transmission cost; otherwise, consumers should bear this cost through capacity payments. Since electric power transmission is a natural monopoly, marginal-cost pricing does not fully cover costs. We propose distributing the revenue deficit among users in proportion to the surplus they derive from the service priced at marginal cost. (Author)
[en] The magnetoelastic contributions to the elastic constants of Ho, Dy, and Tb were determined at temperatures in the paramagnetic range in applied fields up to 75 kG. Magnetization measurements were also made in order to facilitate the comparison of the experimental results with theory. Initially the results were analyzed in terms of a theory due to Southern and Goodings, but the agreement was poor. The field dependence predicted by this theory, using magnetoelastic coupling constants estimated from static magnetostriction data, was generally much smaller than the observed dependence, and, in many cases, the theory did not predict the correct qualitative field or temperature dependence. The reasons for these discrepancies are, apparently, the use by Southern and Goodings of first-order perturbation theory, together with an inappropriate application of finite-strain theory. A calculation of the magnetoelastic contribution to the elastic constants was carried out employing the molecular-field approximation, but without using perturbation theory and using only the conventional small-strain tensor. This approach, similar to that of Freyne, is in much better agreement with the experimental results
[en] The public's perception of risk drives their response to any potential environmental remediation project. Even if the actual environmental and health risks may be relatively low, public perception of high risk may doom the project to an uphill struggle characterized by heated public meetings, negative media coverage, reluctant regulators, project delays and increased costs. The ultimate Catch 22 in such a case is that the contamination remains in-place until the public drama is concluded. This paper explores the development and implementation of a Community Relations Plan for the clean up of a Manufactured Gas Plant (MGP) site owned and operated by corporate predecessors of Arizona Public Service Company (APS) near the turn of the century. The unique challenges associated with this project were that the former MGP was located in downtown Phoenix at the site of a future federal courthouse. Although the MGP site had been under investigation for some time, the clean-up schedule was driven by a tight courthouse construction schedule. Compounding these challenges were the logistics associated with conducting a large-scale cleanup in a congested, highly visible downtown location. An effective Community Relations Plan can mean the difference between the success and failure of an environmental remediation project. Elements of an effective plan are: identifying key stakeholders and involving them in the project from the beginning; providing timely information and being open and honest about the potential environmental and health risks; involving your company's community relations and media staff; and educating affected company employees. The Community Relations Plan developed for this project was designed to alleviate public concern about potential risks (perceived or real) associated with the project by keeping key stakeholders informed of all activities well in advance
[en] A number of countries with oligopolistic power industries have used marginal cost pricing to set the price of energy for small customers. This course of action, however, does not necessarily ensure an efficient outcome when competition is imperfect. The purpose of this paper is to study how the auction of long-term contracts could reduce market power. We do so in a two-firm, two-technology, linear-cost, static model where demand is summarized by a price inelastic load curve. In this context we show that the larger the proportion of total demand auctioned in advance, the lower are both the contract and the average spot price of energy. (author)
[en] A number of countries with oligopolistic power industries have used marginal cost pricing to set the price of energy for small customers. This course of action, however, does not necessarily ensure an efficient outcome when competition is imperfect. The purpose of this paper is to study how the auction of long-term contracts could reduce market power. We do so in a two-firm, two-technology, linear-cost, static model where demand is summarized by a price inelastic load curve. In this context we show that the larger the proportion of total demand auctioned in advance, the lower are both the contract and the average spot price of energy.
[en] Highlights: • This work investigates potential energy savings of an ice cream freezer. • From a full load compressor to a variable speed compressor one in freezer. • 30% less of energy consumption. • It is possible to save between 11 and 14 MWh per year by optimizing freezers. - Abstract: This work investigates potential energy saves in an ice cream freezer by using a variable speed compressor and optimization’s methodology for operating conditions during the process. Two configurations to control the refrigeration capacity were analyzed, the first one, modifies the pressure through the pilot control valve (conventional refrigeration system) and the second one with a variable speed compressor, both with a float expansion valve. Variable speed compressor configuration has showed the highest coefficient of performance and around of 30% less of energy consumption than the conventional one. The optimization of operating conditions in order to minimize the energy consumption is also presented. It was calculated only in France, for all ice cream and sorbet production, it is possible to save energy between 11 and 14 MWh per year by optimizing the operation of the refrigeration system through a variable speed compressor configuration
[en] Inhibition of fibril assembly is a potential therapeutic strategy in neurodegenerative disorders such as prion and Alzheimer's diseases. Highly branched, globular polymers-dendrimers-are novel promising inhibitors of fibril formation. In this study, the effect of polyamidoamine (PAMAM) dendrimers (generations 3rd, 4th, and 5th) on amyloid aggregation of the prion peptide PrP 185-208 and the Alzheimer's peptide Aβ 1-28 was examined. Amyloid fibrils were produced in vitro and their formation was monitored using the dye thioflavin T (ThT). Fluorescence studies were complemented with electron microscopy. The results show that the higher the dendrimer generation, the larger the degree of inhibition of the amyloid aggregation process and the more effective are dendrimers in disrupting the already existing fibrils. A hypothesis on dendrimer-peptide interaction mechanism is presented based on the dendrimers' molecular structure
[en] This work presents the results of the growth and characterization of AlxGa1-xAs/GaAs multilayer structures obtained in a metallic-arsenic-based-MOCVD system. The main goal is to explore the ability of the growth system to grow high quality multilayer structures like quantum wells. The use of metallic arsenic could introduce important differences in the growth process due to the absence of the hydride group V precursor (AsH3), which manifests in the electrical and optical characteristics of both GaAs and AlxGa1-xAs layers. The characterization of these epilayers and structures was performed using low-temperature photoluminescence, Hall effect measurements, X-ray diffraction, Raman spectroscopy, secondary ion mass spectroscopy (SIMS) and Atomic Force Microscopy (AFM). - Research highlights: → This work is reported the growth of AlxGa1-xAs/GaAs/AlxGa1-xAs heterostructures by a solid arsenic based MOCVD system. → The results obtained with this system are comparable with those obtained with the traditional arsine based growth system. → The main limitation of the alternative MOCVD system is related to the lack of monoatomic hydrogen on the growth surface that acts modifying the surface kinetics and enhancing the carbon incorporation. → The experimental results indicate that it can be grown AlxGa1-xAs using elemental arsenic by MOCVD, which can be used to optoelectronic devices.
[en] In this paper, we describe a phase transition in poly (isobutylene) of various molecular weight under elongating stress. Rheometry and wide angle X-ray diffraction have been performed simultaneously to correlate mechanical and structural properties of the material. The low molecular weight samples did not crystallize under the flow in the range of the strain rates applied. On the other hand, as the molecular weight increases the crystallization is always preceded by a strain of the samples under stretching. (Author) 16 figs., 3 tabs
[en] Cuprous oxide (Cu2O) crystals were grown by the two-step crystallization method in air atmosphere conditions from polycrystalline thin copper foils. The method comprises two stages; in the first one the copper plates are oxidized at 1020 deg. C by some hours in line with its initial thickness. In the second stage, the growth of large crystalline areas is promoted by annealing the Cu2O samples at 1100 deg. C for long periods. Raman scattering an X-ray measurements demonstrates the existence of the single-phase Cu2O. The effects on the crystalline structure and photoluminescence (PL) response were studied as a function of the conditions used in the second stage of the synthesis method. PL spectra were taken from 10 to 180 K to define the main radiative recombination paths. Besides the near band excitonic transitions, two strong emission bands at 720 and 920 nm associated with relaxed excitons at oxygen and copper vacancies were detected. Both excitonic-vacancy bond transitions presented similar intensities that are related to the growth method. X-ray and Raman scattering measurements help to assess the samples crystalline quality.