24,596 research outputs found

    Power meter for Highly-Distorted Three-Phase Systems

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    This paper describes a low-cost, three-phase power meter, which is based on a fast, specially designed acquisition board coupled to a PC via the PC parallel/printer port or by means of an AT card. The power associated with the fundamental and first harmonics is computed by software that operates in the time domain and employs a sample-weighting procedure that makes the uncertainty related to the asynchronous sampling negligible. The low-cost acquisition board features two 8-bit 1 MHz converters and a local RAM, which decouples the PC clock from the measurement requirements. Hall effect transducers are used for the current channels and fast differential amplifiers for the voltage channels. The fast sampling frequency allows simple antialiasing filters to be employed. Digital filtering is used to reduce the sample number while increasing the resolution. The power uncertainty provided by this arrangement is less then 0.1 % with 2.5 measurements per second when a low-cost 486DX33-based PC is use

    UTC Dissemination to the Real-Time User

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    The current definition of Coordinated Universal Time (UTC) dates from 1972. The duration of a UTC second is defined in terms of the frequency of a hyperfine transition in the ground state of cesium. This standard frequency is realized in a number of different laboratories using ensembles of commercial cesium clocks and a few primary frequency standards. The data from all of these devices are transmitted periodically to the Bureau International des Poids et Mesures (BIPM) in Sevres, France, where they are combined in a statistical procedure to produce International Atomic Time (TAI). The time of this scale is adjusted as needed ('coordinated') by adding or dropping integer seconds so as to keep it within plus or minus 0.9 s of UT1, a time scale based on the observation of the transit times of stars and corrected for the predicted seasonal variations in these observations. When the leap seconds are included into TAI, the result is called UTC. The difference between TAI and UTC is therefore an exact integer number of seconds. This difference is currently 29 s and will become 30 s at 0 UTC on 1 January 1996

    Omega VLF timing revision 1

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    The report specifically discusses time dissemination techniques, including epoch determination, frequency determination, and ambiguity resolution. It also discusses operational considerations including equipment, path selection, and adjustment procedure. epoch (the actual location or timing of periodic events) is shown to be both maintainable and calibratable by the techniques described to better than 3-microsecond accuracy; and frequency (the uniformity of the time scale) to about one part in 10 to the 12th power

    Waste Not, Want Not: The Potential for Urban Water Conservation in California

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    The largest, least expensive, and most environmentally sound source of water to meet California's future needs is the water currently being wasted in every sector of our economy. This report, "Waste Not, Want Not," strongly indicates that California's urban water needs can be met into the foreseeable future by reducing water waste through cost-effective water-saving technologies, revised economic policies, appropriate state and local regulations, and public education

    Climate Change: An Agenda for Global Collective Action

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    Over the past decade, and especially over the past few years, climate change has emerged as one of the most important issues facing the international community. A global consensus now exists that climate change represents a significant potential threat to the world's well-being. But there is disagreement about how and when to address that threat. To motivate the discussion of both the timing and magnitude of emissions mitigation policy, the paper begins with an overview of the underlying science and economics. Understanding the uncertainties and differences in the timing of costs and benefits of climate change mitigation helps frame the extensive discussion of political economy issues that we examine in the second section. Specifically, we explore the interaction of economic and political concerns in enforcing emissions commitments and encouraging developing country participation within the "voluntaristic" framework entailed by the current system of global governance. Given these political economy constraints, in the third section we evaluate the Kyoto Protocol and alternative formulations to climate change policy. We conclude that modifications to the Kyoto framework are required to advance the effort to address climate change. At the very least, a thorough re-examination of alternative frameworks may prove helpful in building a global consensus behind a more effective strategy. The final section concludes with a discussion of one promising approach to addressing climate change: a flexible hybrid system that combines a permit trading program with the ability of governments to sell additional permits at a given maximum price.Environment, Technology and Industry, Regulatory Reform, Other Topics

    The Valuation of Contaminated Land

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    This paper presents a Monte Carlo based method for explicitly accounting for uncertainty in the valuation of contaminated property. Environmental risk is being quantified by the scientific methods described in this paper. Financial risk is also quantifiable by these techniques. A 1993 Supreme Court case known as Daubert has changed the admission requirements for scientific evidence by expert witnesses. Hoyt (1997) notes that it is "imperative that real estate appraisers who testify be sure that their scientific evidence will stand up to the scrutiny of Daubert of their testimony may be rejected." A scientific method of quantifying the unique financial risk of this type of asset is used for the valuation of contaminated land.

    Climate change adaptation in industry and business

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    This report delivers a best practice framework to integrate financial risk assessment, governance and disclosure with existing governance principles around climate change adaptation.AbstractThe Australian business community has long been aware of the risks and opportunities associated with greenhouse gas mitigation and climate change policies. Some businesses have taken initial steps to adapt to the expected effects of climate change; however, most enterprises are only vaguely aware of the breadth of adaptation that may be required. Associated with strategic adaptation are the principles of financial/operational risk management and governance, as well as financial impact disclosure to investors and regulators. We develop a consolidated framework in which boards and executive managers can develop a robust approach to climate change adaptation governance, climate change risk assessment and financial disclosure. The project outlines a matrix of disclosures required for investors to enable them to evaluate corporate exposure to climate change risk.The project initially comprised a set of workshops with members of the Australian business community, industry representatives, regulatory authorities and academics with expertise in business risk and disclosure effects. Each workshop focused on a separate theme that built upon the work of previous workshops. A set of follow-up discussions was held with some of the key members who contributed to the project, including the Australian Stock Exchange (ASX) Investor Group on Climate Change (IGCC), the Australian Accounting Standards Board (AASB) and the Australian Institute of Company Directors. This discussion permitted each body to comment on the final report, advise on the mechanics of the costing, reporting and disclosure approaches of climate change adaptation, and lend their expertise to the formulation of an appropriate framework.The scope of the research is constrained to firm behaviour and the requirements for investor disclosure and governance of adaptation activities. The project therefore focuses on financial analyses – including real options – undertaken by firms with regard to investing in climate change adaptation activities and projects. While the economic costs and benefits are important to organisational adaptation activities, they represent a secondary level of analysis that may need to be carried out on either an independent or cumulative scale by governments or other bodies to measure the wider effects.As the degree of sophistication in climate change adaptation activities, modelling and cost estimation increases, along with the anticipated growth in interest of both company boards and managers, it is expected that accounting standards, ASX listing rules and disclosures required under the Corporations Act would need to explicitly reflect these corporate actions. The asset allocation of banks, mutual funds, superannuation funds and other investments is also likely to adapt as companies quantify their exposure to climate change. The makeup of assets in investment portfolios may therefore markedly shift, and thus indirectly adjust to the climate change adaptation activities of companies in the broader market

    Synchrophasors: Multilevel Assessment and Data Quality Improvement for Enhanced System Reliability

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    . This study presents a comprehensive framework for testing and evaluation of Phasor Measurement Units (PMUs) and synchrophasor systems under normal power system operating conditions, as well as during disturbances such as faults and transients. The proposed framework suggests a performance assessment to be conducted in three steps: (a) type testing: conducted in the synchrophasor calibration laboratory according to accepted industrial standards; (b) application testing: conducted to evaluate the performance of the PMUs under faults, transients, and other disturbances in power systems; (c) end-to-end system testing: conducted to assess the risk and quantify the impact of measurement errors on the applications of interest. The suggested calibration toolset (type testing) enables performance characterization of different design alternatives in a standalone PMU (e.g., length of phasor estimation windows, filtering windows, reporting rates, etc.). In conjunction with the standard performance requirements, this work defines new metrics for PMU performance evaluations under any static and dynamic conditions that may unfold in the grid. The new metrics offer a more realistic understanding of the overall PMU performance and help users choose the appropriate device/settings for the target applications. Furthermore, the proposed probabilistic techniques quantify the PMU accuracy to various test performance thresholds specified by corresponding IEEE standards, rather than having only the pass/fail test outcome, as well as the probability of specific failures to meet the standard requirements defined in terms of the phasor, frequency, and rate of change of frequency accuracy. Application testing analysis encompasses PMU performance evaluation under faults and other prevailing conditions, and offers a realistic assessment of the PMU measurement errors in real-world field scenarios and reveals additional performance characteristics that are crucial for the overall application evaluation. End-to-end system tests quantify the impact of synchrophasor estimation errors and their propagation from the PMU towards the end-use applications and evaluate the associated risk. In this work, extensive experimental results demonstrate the advantages of the proposed framework and its applicability is verified through two synchrophasor applications, namely: Fault Location and Modal Analysis. Finally, a data-driven technique (Principal Component Pursuit) is proposed for the correction and completion of the synchrophasor data blocks, and its application and effectiveness is validated in modal analyzes
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