WorldWideScience

Sample records for refueling outage duration

  1. Integrated head area design of KNGR to reduce refueling outage duration

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Woo Tae; Park, Chi Yong; Kim, In Hwan; Kim, Dae Woong [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    In the design of KNGR (Korea Next Generation Reactor), we believe that economy is one of the most important factors to be considered. Thus, we reviewed and evaluated the consequences of designing the head area into an integrated package from an economical point of view. The refueling outage durations of the nuclear power plants currently in operation in Korea, some having and others not having integrated head package, are compared. This paper discusses the characteristics of head area design and the critical design issues of KNGR head area to evaluate the effect of the head area characteristics on the outage duration. 8 refs., 4 figs. (Author)

  2. Refueling outage availability study. Phase 1 final report

    Energy Technology Data Exchange (ETDEWEB)

    Thomasson, F.R.

    1977-11-01

    Babcock and Wilcox entered into a contract with the Department of Energy (formerly the Energy Research and Development Administration) for the performance of a refueling outage availability study with the cooperation of Duke Power Company and Arkansas Power and Light Company. The objective was to improve plant availability through reduction of refueling outage time. The conclusions of the study were drawn from data gathered during the 1976 Oconee 3 and 1977 Arkansas Unit One refueling outages. The onsite effort was one of observation and data recording, which included time-lapsed photography and video tape. The collected data were then evaluated and analyzed for potential improvements and to identify in detail where resources were consumed. The overall result was a listing of (1) specific recommendations for implementing improvements in the facilities, equipment, tools, procedures, and techniques for the participating utilities; (2) generic recommendations of immediate benefit to other applicable utilities; and (3) recommendations for further work in the succeeding phases of the DOE program. The results indicate that, by incorporating the recommendations and taking credit for the time savings, an ideal refueling outage length of 21 to 22 days for the nuclear steam system (NSS) could be realized. Additional benefits would be a reduction in man-Rem exposure and manpower requirements.

  3. Improvement of availability of PWR nuclear plants through the reduction of the time required for refueling/maintenance outages

    Energy Technology Data Exchange (ETDEWEB)

    Mayers, J.B.; Soth, L.G.

    1978-04-01

    The objective of the project, conducted by Commonwealth Research Corporation and Westinghouse Electric Corporation, is to identify improvements in procedures and equipment which will reduce the time required for refueling/maintenance outages at PWR nuclear power plants. The outage of Commonwealth Edison Zion Station Unit 1 in March through May of 1976 was evaluated to identify those items which caused delays and those work activities that offer the potential for significant improvements that could reduce the overall duration of the outage and achieve an improvement in the plant's availability for power production. Modifications in procedures have been developed and were evaluated during one or more outages in 1977. Conceptual designs have been developed for equipment modifications to the refueling system that could reduce the time required for the refueling portion of the outage. The purpose of the interim report is to describe those conceptual designs and to assess their impact upon future outages. Recommendations are included for the implementation of these equipment improvements in a continuation of this program as a demonstration of plant availability benefits that can be realized in PWR nuclear plants already in operation or under construction.

  4. Improvement of availability of PWR nuclear plants through the reduction of the time required for refueling/maintenance outages, Phase 1. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, C.A.

    1978-08-01

    The objective of this project is to identify improvements in procedures and equipment which will reduce the time required for refueling/maintenance outages at PWR nuclear power plants. The outage of Commonwealth Edison Zion Station Unit 1 in March through May of 1976 was evaluated to identify those items which caused delays and those work activities that offer the potential for significant improvements toward reducing its overall duration. Thus, the plant's availability for power production would be increased. Revisions in procedures and some equipment modifications were implemented and evaluated during the Zion Unit 2 refueling/maintenance outage beginning in January 1977. Analysis of the observed data has identified benefits available through improved refueling equipment and also areas where additional new, innovative refueling, or refueling-related equipment should be beneficial. A number of specific design concepts are recommended as a result of Phase 1. In addition, a new master planning mechanism is described for implementation during subsequent planned outages at Zion Station. This final report describes the recommended conceptual designs and planning mechanism and assesses their impact upon future outages. Their effect on savings in refueling time, labor, and radiation exposure is discussed. The estimated economic payoff for these concepts was found to be of such significance that an additional phase of the program is warranted. During this extended phase, a more detailed engineering study should be undertaken to determine the cost of implementation along with more specific estimates of the benefits for PWR plants already in operation or under construction.

  5. Refueling outage services in Spanish Nuclear Power Plants; Servicios en recargas de centrales nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Landete, J. L.; Soto, M.; Nunuez, A.

    2007-07-01

    DOMINGUIS Group, through its 75 years of business development, has positioned as the Spanish leader Group in Services for the Nuclear Energy and Petrochemical Sectors. In this article, we present the most significant services summary that, through the companies that constitute DOMINGUIS Group, we have developed in Refueling Outage in Spanish Nuclear Power Plants. (Author)

  6. Comparison and validation of statistical methods for predicting power outage durations in the event of hurricanes.

    Science.gov (United States)

    Nateghi, Roshanak; Guikema, Seth D; Quiring, Steven M

    2011-12-01

    This article compares statistical methods for modeling power outage durations during hurricanes and examines the predictive accuracy of these methods. Being able to make accurate predictions of power outage durations is valuable because the information can be used by utility companies to plan their restoration efforts more efficiently. This information can also help inform customers and public agencies of the expected outage times, enabling better collective response planning, and coordination of restoration efforts for other critical infrastructures that depend on electricity. In the long run, outage duration estimates for future storm scenarios may help utilities and public agencies better allocate risk management resources to balance the disruption from hurricanes with the cost of hardening power systems. We compare the out-of-sample predictive accuracy of five distinct statistical models for estimating power outage duration times caused by Hurricane Ivan in 2004. The methods compared include both regression models (accelerated failure time (AFT) and Cox proportional hazard models (Cox PH)) and data mining techniques (regression trees, Bayesian additive regression trees (BART), and multivariate additive regression splines). We then validate our models against two other hurricanes. Our results indicate that BART yields the best prediction accuracy and that it is possible to predict outage durations with reasonable accuracy. © 2011 Society for Risk Analysis.

  7. 中核运行二厂大修辐射防护管理经验%The Radiation Protection Management Experience for Refueling Outage of NPP 2, CNNC Nuclear Power Operations Management Limited Company

    Institute of Scientific and Technical Information of China (English)

    倪伟; 陈高飞; 刘杰; 稂其良

    2013-01-01

    Since commercial operation in 2002, the NPP 2 of CNNO has been safe in operation for twelve years,and finished RP control successfuly in the 22 refueling outages. During the twelve years'operation, the RP management system was established and developed constantly, it also made good achievements in RP supervision and management. The author summarized the relevant RP management experience of refueling outages of CNNO Qinshan NPP 2, introduced the RP control actions for each stage of refueling outage, and discussed the key points and difficulty of RP control in refueling outage.%中核核电运行管理有限公司二厂(简称中核运行二厂)自2002年商业运行以来,已安全运行12个年头,顺利完成了22次换料大修的辐射安全控制,在12年的生产实践中,建立并不断完善了大修辐射管理体系,在历次大修中较好的发挥了辐射安全监督与管理的职能。本文总结了中核运行二厂大修辐射防护管理经验,系统地介绍了大修各阶段辐射防护控制所采取的行动,并对大修辐射防护管理的重点及难点进行探讨。

  8. Evaluation of potential severe accidents during low power and shutdown operations at Grand Gulf, Unit 1. Volume 5: Analysis of core damage frequency from seismic events for plant operational state 5 during a refueling outage

    Energy Technology Data Exchange (ETDEWEB)

    Budnitz, R.J. [Future Resources Associates, Inc., Berkeley, CA (United States); Davis, P.R. [PRD Consulting (United States); Ravindra, M.K.; Tong, W.H. [EQE International, Inc., Irvine, CA (United States)

    1994-08-01

    In 1989 the US Nuclear Regulatory Commission (NRC) initiated an extensive program to examine carefully the potential risks during low-power and shutdown operations. The program included two parallel projects, one at Sandia National Laboratories studying a boiling water reactor (Grand Gulf), and the other at Brookhaven National Laboratory studying a pressurized water reactor (Surry Unit 1). Both the Sandia and Brookhaven projects have examined only accidents initiated by internal plant faults---so-called ``internal initiators.`` This project, which has explored the likelihood of seismic-initiated core damage accidents during refueling outage conditions, is complementary to the internal-initiator analyses at Brookhaven and Sandia. This report covers the seismic analysis at Grand Gulf. All of the many systems modeling assumptions, component non-seismic failure rates, and human effort rates that were used in the internal-initiator study at Grand Gulf have been adopted here, so that the results of the study can be as comparable as possible. Both the Sandia study and this study examine only one shutdown plant operating state (POS) at Grand Gulf, namely POS 5 representing cold shutdown during a refueling outage. This analysis has been limited to work analogous to a level-1 seismic PRA, in which estimates have been developed for the core-damage frequency from seismic events during POS 5. The results of the analysis are that the core-damage frequency for earthquake-initiated accidents during refueling outages in POS 5 is found to be quite low in absolute terms, less than 10{sup {minus}7}/year.

  9. Evaluation of potential severe accidents during low power and shutdown operations at Grand Gulf, Unit 1: Analysis of core damage frequency from internal events for Plant Operational State 5 during a refueling outage. Volume 2, Part 3: Internal Events Appendices I and J

    Energy Technology Data Exchange (ETDEWEB)

    Yakle, J. [Science Applications International Corp., Albuquerque, NM (United States); Darby, J. [Science and Engineering Associates, Inc., Albuquerque, NM (United States); Whitehead, D.; Staple, B. [Sandia National Labs., Albuquerque, NM (United States)

    1994-06-01

    This report provides supporting documentation for various tasks associated with the performance of the probablistic risk assessment for Plant Operational State 5 during a refueling outage at Grand Gulf, Unit 1 as documented in Volume 2, Part 1 of NUREG/CR-6143.

  10. Application and improvement of high risk operations control during refueling outage of Qinshan Nuclear Power Plant%秦山核电厂换料大修高风险作业控制应用及优化

    Institute of Scientific and Technical Information of China (English)

    苏松

    2014-01-01

    根据秦山核电厂三十万千瓦机组换料大修高风险作业控制实践经验,介绍一种基于安全许可管理的大修高风险作业控制模式,将高风险作业控制流程嵌入电站生产管理系统,与工单直接关联,实现了高危作业活动识别、风险分析及安全防护措施制定电子流程化。通过对电厂最近六次机组换料大修高风险作业控制相关数据统计、比较,评价高风险作业控制模式在电厂大修中应用效果的稳定性与有效性;根据核电厂大修类作业项目特点,提出机组换料大修期间大纲作业项目高风险作业控制改进方向。%According to the practical experience from Qinshan Nuclear Power Plant,a control mode of high risk op-erations control based on industry safety permission was introduced. The high risk operations control flow was em-bedded in the electronic production management system of Qinshan Nuclear Power Plant,which connected with tasks straightly and realized the electronic workflow of high risk activity recognition,risk analysis and drawing of safety protection measures. By counting and comparing the data of high risk operations control from the recent six times refueling outages of power plant,the stability and effectiveness for application of high risk operations control mode were appraised. According to the characteristics of fixed project during refueling outage of nuclear power plant,the improvement directions of high risk operations control were presented.

  11. Evaluation of potential severe accidents during low power and shutdown operations at Grand Gulf, Unit 1. Volume 2, Part 1C: Analysis of core damage frequency from internal events for plant operational State 5 during a refueling outage, Main report (Sections 11--14)

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, D. [Sandia National Labs., Albuquerque, NM (United States); Darby, J. [Science and Engineering Associates, Inc., Albuquerque, NM (United States); Yakle, J. [Science Applications International Corp., Albuquerque, NM (United States)] [and others

    1994-06-01

    This document contains the accident sequence analysis of internally initiated events for Grand Gulf, Unit 1 as it operates in the Low Power and Shutdown Plant Operational State 5 during a refueling outage. The report documents the methodology used during the analysis, describes the results from the application of the methodology, and compares the results with the results from two full power analyses performed on Grand Gulf.

  12. Power Outages

    Science.gov (United States)

    ... Thunderstorms & Lightning Tornadoes Tsunamis Volcanoes Wildfires Main Content Power Outages This page provides basic safety tips and ... during and after a power outage. Before a Power Outage Build or restock your emergency preparedness kit , ...

  13. Evaluation of potential severe accidents during low power and shutdown operations at Grand Gulf, Unit 1: Evaluation of severe accident risks for plant operational state 5 during a refueling outage. Main report and appendices, Volume 6, Part 1

    Energy Technology Data Exchange (ETDEWEB)

    Brown, T.D.; Kmetyk, L.N.; Whitehead, D.; Miller, L. [Sandia National Labs., Albuquerque, NM (United States); Forester, J. [Science Applications International Corp., Albuquerque, NM (United States); Johnson, J. [GRAM, Inc., Albuquerque, NM (United States)

    1995-03-01

    Traditionally, probabilistic risk assessments (PRAS) of severe accidents in nuclear power plants have considered initiating events potentially occurring only during full power operation. Recent studies and operational experience have, however, implied that accidents during low power and shutdown could be significant contributors to risk. In response to this concern, in 1989 the Nuclear Regulatory Commission (NRC) initiated an extensive program to carefully examine the potential risks during low power and shutdown operations. Two plants, Surry (pressurized water reactor) and Grand Gulf (boiling water reactor), were selected as the plants to be studied. The program consists of two parallel projects being performed by Brookhaven National Laboratory (Surry) and Sandia National Laboratories (Grand Gulf). The program objectives include assessing the risks of severe accidents initiated during plant operational states other than full power operation and comparing the estimated risks with the risk associated with accidents initiated during full power operation as assessed in NUREG-1150. The scope of the program is that of a Level-3 PRA. The subject of this report is the PRA of the Grand Gulf Nuclear Station, Unit 1. The Grand Gulf plant utilizes a 3833 MWt BUR-6 boiling water reactor housed in a Mark III containment. The Grand Gulf plant is located near Port Gibson, Mississippi. The regime of shutdown analyzed in this study was plant operational state (POS) 5 during a refueling outage, which is approximately Cold Shutdown as defined by Grand Gulf Technical Specifications. The entire PRA of POS 5 is documented in a multi-volume NUREG report (NUREG/CR-6143). The internal events accident sequence analysis (Level 1) is documented in Volume 2. The Level 1 internal fire and internal flood analyses are documented in Vols 3 and 4, respectively.

  14. Outage management: A case study

    Energy Technology Data Exchange (ETDEWEB)

    Haber, S.B.; Barriere, M.T. (Brookhaven National Lab., Upton, NY (United States)); Roberts, K.H. (California Univ., Berkeley, CA (United States). Walter A. Haas School of Business)

    1992-01-01

    Outage management issues identified from a field study conducted at a two-unit commercial pressurized water reactor (PWR), when one unit was in a refueling outage and the other unit was at full power operation, are the focus of this paper. The study was conduced as part of the US Nuclear Regulatory Commission's (NRC) organizational factors research program, and therefore the issues to be addressed are from an organizational perspective. Topics discussed refer to areas identified by the NRC as critical for safety during shutdown operations, including outage planning and control, personnel stress, and improvements in training and procedures. Specifically, issues in communication, management attention, involvement and oversight, administrative processes, organizational culture, and human resources relevant to each of the areas are highlighted by example from field data collection. Insights regarding future guidance in these areas are presented based upon additional data collection subsequent to the original study.

  15. Outage management: A case study

    Energy Technology Data Exchange (ETDEWEB)

    Haber, S.B.; Barriere, M.T. [Brookhaven National Lab., Upton, NY (United States); Roberts, K.H. [California Univ., Berkeley, CA (United States). Walter A. Haas School of Business

    1992-09-01

    Outage management issues identified from a field study conducted at a two-unit commercial pressurized water reactor (PWR), when one unit was in a refueling outage and the other unit was at full power operation, are the focus of this paper. The study was conduced as part of the US Nuclear Regulatory Commission`s (NRC) organizational factors research program, and therefore the issues to be addressed are from an organizational perspective. Topics discussed refer to areas identified by the NRC as critical for safety during shutdown operations, including outage planning and control, personnel stress, and improvements in training and procedures. Specifically, issues in communication, management attention, involvement and oversight, administrative processes, organizational culture, and human resources relevant to each of the areas are highlighted by example from field data collection. Insights regarding future guidance in these areas are presented based upon additional data collection subsequent to the original study.

  16. Development of Methodologies for Technology Deployment for Advanced Outage Control Centers that Improve Outage Coordination, Problem Resolution and Outage Risk Management

    Energy Technology Data Exchange (ETDEWEB)

    Shawn St. Germain; Ronald Farris; Heather Medeman

    2013-09-01

    This research effort is a part of the Light-Water Reactor Sustainability (LWRS) Program, which is a research and development (R&D) program sponsored by Department of Energy (DOE) and performed in close collaboration with industry R&D programs that provides the technical foundations for licensing and managing the long-term, safe, and economical operation of current nuclear power plants. The LWRS program serves to help the U.S. nuclear industry adopt new technologies and engineering solutions that facilitate the continued safe operation of the plants and extension of the current operating licenses. The long term viability of existing nuclear power plants in the U.S. will depend upon maintaining high capacity factors, avoiding nuclear safety issues and reducing operating costs. The slow progress in the construction on new nuclear power plants has placed in increased importance on maintaining the output of the current fleet of nuclear power plants. Recently expanded natural gas production has placed increased economic pressure on nuclear power plants due to lower cost competition. Until recently, power uprate projects had steadily increased the total output of the U.S. nuclear fleet. Errors made during power plant upgrade projects have now removed three nuclear power plants from the U.S. fleet and economic considerations have caused the permanent shutdown of a fourth plant. Additionally, several utilities have cancelled power uprate projects citing economic concerns. For the past several years net electrical generation from U.S. nuclear power plants has been declining. One of few remaining areas where significant improvements in plant capacity factors can be made is in minimizing the duration of refueling outages. Managing nuclear power plant outages is a complex and difficult task. Due to the large number of complex tasks and the uncertainty that accompanies them, outage durations routinely exceed the planned duration. The ability to complete an outage on or near

  17. Development of Improved Graphical Displays for an Advanced Outage Control Center, Employing Human Factors Principles for Outage Schedule Management

    Energy Technology Data Exchange (ETDEWEB)

    St Germain, Shawn Walter [Idaho National Lab. (INL), Idaho Falls, ID (United States); Farris, Ronald Keith [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thomas, Kenneth David [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-01

    The long-term viability of existing nuclear power plants in the United States (U.S.) is dependent upon a number of factors, including maintaining high capacity factors, maintaining nuclear safety, and reducing operating costs, particularly those associated with refueling outages. Refueling outages typically take 20-30 days, and for existing light water NPPs in the U.S., the reactor cannot be in operation during the outage. Furthermore, given that many NPPs generate between $1-1.5 million/day in revenue when in operation, there is considerable interest in shortening the length of refueling outages. Yet refueling outages are highly complex operations, involving multiple concurrent and dependent activities that are somewhat challenging to coordinate; therefore, finding ways to improve refueling outage performance, while maintaining nuclear safety has proven to be difficult. The Advanced Outage Control Center (AOCC) project is a research and development (R&D) demonstration activity under the LWRS Program. LWRS is an R&D program that works closely with industry R&D programs to establish technical foundations for the licensing and managing of long-term, safe, and economical operation of current fleet of NPPs. As such, the LWRS Advanced Outage Control Center project has the goal of improving the management of commercial NPP refueling outages. To accomplish this goal, INL is developing an advanced outage control center (OCC) that is specifically designed to maximize the usefulness of communication and collaboration technologies for outage coordination and problem resolution activities. The overall focus is on developing an AOCC with the following capabilities that enables plant and OCC staff to; Collaborate in real-time to address emergent issues; Effectively communicate outage status to all workers involved in the outage; Effectively communicate discovered conditions in the field to the OCC; Provide real-time work status; Provide automatic pending support notifications

  18. Integrated services of refuelling activities; Servicios Integrados de actividades de recarga

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Valcarcel, M.

    2004-07-01

    One of the widespread tendencies to reach the objectives that the nuclear power plants settle down in their refuelling outages is the use of an integrated service for refuelling activities. In this article, the advantages or reasons of this service are exposed, as well as the integrated refuelling activities service, inside containment, that Tecnatom, Westinghouse and ENUSA have given for the Asco and Vandellos II NPPs, with their results and conclusions. (Author)

  19. Status Report on the Development of Micro-Scheduling Software for the Advanced Outage Control Center Project

    Energy Technology Data Exchange (ETDEWEB)

    Germain, Shawn St. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thomas, Kenneth [Idaho National Lab. (INL), Idaho Falls, ID (United States); Farris, Ronald [Idaho National Lab. (INL), Idaho Falls, ID (United States); Joe, Jeffrey [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-09-01

    The long-term viability of existing nuclear power plants (NPPs) in the United States (U.S.) is dependent upon a number of factors, including maintaining high capacity factors, maintaining nuclear safety, and reducing operating costs, particularly those associated with refueling outages. Refueling outages typically take 20-30 days, and for existing light water NPPs in the U.S., the reactor cannot be in operation during the outage. Furthermore, given that many NPPs generate between $1-1.5 million/day in revenue when in operation, there is considerable interest in shortening the length of refueling outages. Yet, refueling outages are highly complex operations, involving multiple concurrent and dependent activities that are difficult to coordinate. Finding ways to improve refueling outage performance while maintaining nuclear safety has proven to be difficult. The Advanced Outage Control Center project is a research and development (R&D) demonstration activity under the Light Water Reactor Sustainability (LWRS) Program. LWRS is a R&D program which works with industry R&D programs to establish technical foundations for the licensing and managing of long-term, safe, and economical operation of current NPPs. The Advanced Outage Control Center project has the goal of improving the management of commercial NPP refueling outages. To accomplish this goal, this INL R&D project is developing an advanced outage control center (OCC) that is specifically designed to maximize the usefulness of communication and collaboration technologies for outage coordination and problem resolution activities. This report describes specific recent efforts to develop a capability called outage Micro-Scheduling. Micro-Scheduling is the ability to allocate and schedule outage support task resources on a sub-hour basis. Micro-Scheduling is the real-time fine-tuning of the outage schedule to react to the actual progress of the primary outage activities to ensure that support task resources are

  20. Renew, refuel, and rebuild.

    Science.gov (United States)

    Chin, Allison

    2009-01-01

    We can renew, refuel, and rebuild America with millions of green jobs, but they must be good jobs. Participants at the conference understand that environmental and economic stability go hand-in-hand, that the challenges of global warming are urgent and that huge opportunities exist for building a clean energy economy.

  1. 47 CFR 4.5 - Definitions of outage, special offices and facilities, and 911 special facilities.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Definitions of outage, special offices and... Definitions of outage, special offices and facilities, and 911 special facilities. (a) Outage is defined as a...-911 tandems/selective routers for at least 30 minutes duration; or (3) One or more end-office or...

  2. BWR Servicing and Refueling Improvement Program: Phase I summary report

    Energy Technology Data Exchange (ETDEWEB)

    Perry, D.R.

    1978-09-01

    Under the U.S. Department of Energy sponsorship, General Electric Co. (GE) undertook a study of boiling water reactor (BWR) refueling outages for the purpose of recommending the development and demonstration of critical path time savings improvements. The Tennessee Valley Authority (TVA) joined the study as a subcontractor, providing monitoring assistance and making the Browns Ferry Site available for improvement demonstrations. Agreement was also reached with Georgia Power Co., Power Authority of the State of New York, and Commonwealth Edison Co. for monitoring and data collection at Hatch 1, FitzPatrick, and Quad Cities 1 nuclear plants, respectively. The objective was to identify, develop, and demonstrate improved refueling, maintenance, and inspection procedures and equipment. The improvements recommended in this study are applicable to BWR nuclear plants currently in operation as well as those in the design and construction phases. The recommendations and outage information can be used as a basis to plan and conduct the first outages of new plants and to improve the planning and facilities of currently operating plants. Many of the recommendations can readily be incorporated in plants currently in the design and construction phases as well as in the design of future plants. Many of these recommended improvements can be implemented immediately by utilities without further technical development.

  3. Shopping for outage management systems

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Y.C.; Konneker, L.K.; Watkins, T.R.

    1995-12-31

    Customer service is becoming increasingly important to electric utilities. Outage management is an important part of customer service. Good outage management means quickly responding to outages and keeping customers informed about outages. Each outage equals lost customer satisfaction and lost revenue. Outage management is increasingly important because of new competition among utilities for customers, pressure from regulators, and internal pressure to cut costs. The market has several existing software products for outage management. How does a utility judge whether these products satisfy their specific needs? Technology is changing rapidly to support outage management. Which technology is proven and cost-effective? The purpose of this paper is to outline the procedure for evaluating outage management systems, and to discuss the key features to look for. It also gives our opinion of the features that represent state of the art. This paper will not discuss specific products or list vendors names.

  4. Use of collaboration software to improve nuclear power plant outage management

    Energy Technology Data Exchange (ETDEWEB)

    Germain, Shawn

    2015-02-01

    Nuclear Power Plant (NPP) refueling outages create some of the most challenging activities the utilities face in both tracking and coordinating thousands of activities in a short period of time. Other challenges, including nuclear safety concerns arising from atypical system configurations and resource allocation issues, can create delays and schedule overruns, driving up outage costs. Today the majority of the outage communication is done using processes that do not take advantage of advances in modern technologies that enable enhanced communication, collaboration and information sharing. Some of the common practices include: runners that deliver paper-based requests for approval, radios, telephones, desktop computers, daily schedule printouts, and static whiteboards that are used to display information. Many gains have been made to reduce the challenges facing outage coordinators; however; new opportunities can be realized by utilizing modern technological advancements in communication and information tools that can enhance the collective situational awareness of plant personnel leading to improved decision-making. Ongoing research as part of the Light Water Reactor Sustainability Program (LWRS) has been targeting NPP outage improvement. As part of this research, various applications of collaborative software have been demonstrated through pilot project utility partnerships. Collaboration software can be utilized as part of the larger concept of Computer-Supported Cooperative Work (CSCW). Collaborative software can be used for emergent issue resolution, Outage Control Center (OCC) displays, and schedule monitoring. Use of collaboration software enables outage staff and subject matter experts (SMEs) to view and update critical outage information from any location on site or off.

  5. Modelling lightning caused transmission line outages in Alberta

    Energy Technology Data Exchange (ETDEWEB)

    Wu, M.; Shen, S.S.P. [Alberta Univ., Edmonton, AB (Canada). Dept. of Mathematical and Statistical Sciences; Koval, D.O. [Alberta Univ., Edmonton, AB (Canada). Dept. of Electrical Engineering

    2005-07-01

    The characteristics of lightning and the relationship between lightning and transmission line outages is not fully understood by utility planners. This study used 20 year data sets of lightning events to investigate the spatial and temporal patterns of lightning in Alberta. Studies of geographical and temporal characteristics of lightning caused transmission line outages for several voltage level transmission lines were also examined. A lasso regression variable selection procedure and Cp criterion were used to model the duration of the lightning-caused transmission line outages as a function of weather and lightning patterns. The province was divided into 110 by 110 grids, and lightning variables were calculated for each cell. All the lightning variables for each cell were then averaged based on their areas. The overall cloud-ground lightning flashes 20-year mean frequency and the physical locations of power transmission lines were then plotted. Estimated probability density functions of the duration of lightning caused transmission line outages were classified by their voltage levels. The study showed that the characteristics of the lightning caused outages were different for different voltage levels of the transmission lines. Results suggested that the findings will have a significant impact on the accuracy of reliability methodologies that use the average duration of transmission line outages in their calculations. It was concluded that the new methodology can be applied to any transmission line system operating in a unique geographical environmental area. 11 refs., 3 tabs., 5 figs.

  6. Does NASA SMAP Improve the Accuracy of Power Outage Models?

    Science.gov (United States)

    Quiring, S. M.; McRoberts, D. B.; Toy, B.; Alvarado, B.

    2016-12-01

    Electric power utilities make critical decisions in the days prior to hurricane landfall that are primarily based on the estimated impact to their service area. For example, utilities must determine how many repair crews to request from other utilities, the amount of material and equipment they will need to make repairs, and where in their geographically expansive service area to station crews and materials. Accurate forecasts of the impact of an approaching hurricane within their service area are critical for utilities in balancing the costs and benefits of different levels of resources. The Hurricane Outage Prediction Model (HOPM) are a family of statistical models that utilize predictions of tropical cyclone windspeed and duration of strong winds, along with power system and environmental variables (e.g., soil moisture, long-term precipitation), to forecast the number and location of power outages. This project assesses whether using NASA SMAP soil moisture improves the accuracy of power outage forecasts as compared to using model-derived soil moisture from NLDAS-2. A sensitivity analysis is employed since there have been very few tropical cyclones making landfall in the United States since SMAP was launched. The HOPM is used to predict power outages for 13 historical tropical cyclones and the model is run using twice, once with NLDAS soil moisture and once with SMAP soil moisture. Our results demonstrate that using SMAP soil moisture can have a significant impact on power outage predictions. SMAP has the potential to enhance the accuracy of power outage forecasts. Improved outage forecasts reduce the duration of power outages which reduces economic losses and accelerates recovery.

  7. Evaluation of Distribution Network Customer Outage Costs

    Science.gov (United States)

    Zemīte, Laila; Gerhards, Jānis

    2009-01-01

    Customer outage cost criteria are considered, collected and analyzed outage costs in Latvia distribution network, as well as distribution network outage elimination structure, the most common outage causes, are proposed outage costs estimation model. Finally the discussion of results of expected customer outage costs and interrupted energy assessment rate calculation results in Latvia distribution network in 2007 are presented, based on customers' mean value of incomes, outcomes and profitability.

  8. Reliability assessment to determine the optimal forced outage rate of components

    Directory of Open Access Journals (Sweden)

    Habib Daryabad

    2014-03-01

    Full Text Available Determining the optimal forced outage rate (FOR ofcomponents can lead to reducing the operational and maintenance costs inelectric power systems. FOR is closely associated with two factors: number ofoutages and duration of outages. Therefore, it is possible to decrease the FORthrough decreasing the number of outages or reducing the duration ofoutages. Decreasing number of outages is usually carried out throughreinforcement of the network and reducing the duration of outages is mainlyperformed through increasing the repair and maintenance groups. Both of theproposed methods to decrease the FOR possess the costs. Therefore, it is verysuitable to find the optimal rate of FOR and avoiding unnecessary costs. Thispaper presents a new methodology to find the optimal rate of FOR. In thisregard, the system reliability is assessed and evaluated from view of FOR andthe optimal rate of FOR is denoted for all components.

  9. Approximate Dynamic Programming and Aerial Refueling

    Science.gov (United States)

    2007-06-01

    were values derived from “AFPAM 10-1403, AIR MOBILITY PLANNING FACTORS” used by the US Air Force when making gross calculations of aerial refueling...Aerial Refueling. U.S. Centennial of Flight Commision. centennialofflight.gov/essay/EvolutionofT echnology /refueling?Tech22.htm. 20003. 5 [6] DOD Needs

  10. Aerial Refueling Clearance Initiation Request

    Science.gov (United States)

    2016-07-14

    fund sharing options.................................................................................. 18 3.12 ATP 3.3.4.2...publication of the original document and its eventual publication in ATP -56 (B). Workgroup 5 spent several Workgroup/JSB sessions reviewing and updating...Clearance Compatibility Assessment Checklist. 21 Aug 2014 ATP 3.3.4.2 SRD 1 - Guide to Obtaining AAR Refuelling Clearances & Compatibility Certification

  11. Outages planning; Planificacion de recargas

    Energy Technology Data Exchange (ETDEWEB)

    Blanquer, N.

    2010-07-01

    The reason of a nuclear power plant outage seems easy. Replace 1/3 of the total core fuel inside reactor for a new, store the old one in a pool and shuffle the rest 2/3 in other positions in the core to optimize fuel burn up. Also is needed to make the preventive, corrective and conservative maintenance, the selected design changes and the regulatory and technical requirements for equipment and systems. To make the plant outage strategy for all the above pack with nuclear safety not challenged is the objective of this article for the Spanish Nuclear Society magazine. (Author)

  12. Outage maintenance checks on large generator windings

    Energy Technology Data Exchange (ETDEWEB)

    Nindra, B.; Jeney, S.I.; Slobodinsky, Y. [National Electric Coil, Columbus, OH (United States)

    1995-12-31

    In the present days of austerity, more constraints and pressures are being brought on the maintenance engineers to certify the generators for their reliability and life extension. The outages are shorter and intervals between the outages are becoming longer. The annual outages were very common when utilities had no regulatory constraints and also had standby capacities. Furthermore, due to lean and mean budgets, outage maintenance programs are being pursued more aggressively, so that longer interval outages can be achieved to ensure peak generator performance. This paper will discuss various visual checks, electrical tests and recommended fixes to achieve the above mentioned objectives, in case any deficiencies are found.

  13. Analysis on the LODHR Event during Refueling Pool Operation

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Dong Hyun; Huh, Jae Young; Lee, Gyu Cheon; Kim, Shin Whan [KEPCO E and C, Inc., Daejeon (Korea, Republic of)

    2015-10-15

    In this paper, the analysis is performed to evaluate the time to core uncovery and core damage as well as the time to core boiling. To analyze thermal hydraulic behaviors during refueling pool operation, RELAP5/MOD3.3 is used adopting the Henry-Fauske (H-F) critical flow model. The input modeling method adopts the method of SFP. The purpose of the analysis is to study the major results and T-H behaviors regarding to safety aspect during LODHR event at the refueling pool operation. In the present low power and shutdown (LPSD) probabilistic safety assessment (PSA) thermal hydraulic (T-H) analysis for dealing with various different plant operational states (POSs), the T-H analysis for the duration of refueling pool operation is omitted as it is considered less severe procedure during overhaul period for optimized power reactor 1000 (OPR1000). Instead only spent fuel pool analysis has been performed representing refueling operation mode (operation mode 6). However, in NUREG-1449, the NRC staff identified twelve technical issues that warrant further evaluation regarding shutdown and low power operation at U.S commercial nuclear power plants. One of issues identified for further evaluation is to evaluate the effect of PWR upper internals, that is, the PWR upper internals may inhibit water in the refueling pool from entering the core during a loss of decay heat removal event (LODHR). Per a commission paper (SECY-91-283) which reported progress to date on the evaluation, the NRC staff requested to address this safety issue by performing a quantitative and qualitative analysis. An analysis of LODHR was performed for advanced power reactor 1400 (APR1400) but it was focused to evaluate the initiation time of core boiling. As the results of the analysis for the LODHR during refueling pool operation, even though the core boiling is occurred in 15 minutes, there is enough water to cover the core and it prevents the core from damaging. The time is taken more than 4 days until the

  14. Outage capacity of multicarrier systems

    KAUST Repository

    Yilmaz, Ferkan

    2010-01-01

    The probability density function and the cumulative distribution function of the product of shifted Gamma variates are obtained in terms of the generalized Fox\\'s H function. Using these new results, the exact outage capacity of multi carrier transmission through a slow Nakagami-m fading channel is presented. Moreover, it is shown that analytical and simulation results are in perfect agreement. © 2009 IEEE.

  15. Enhanced methods for operating refueling station tube-trailers to reduce refueling cost

    Energy Technology Data Exchange (ETDEWEB)

    Elgowainy, Amgad; Reddi, Krishna

    2017-08-22

    A method and apparatus are provided for operating a refueling station including source tube-trailers and at least one compressor to reduce refueling cost. The refueling station includes a gaseous fuel supply source including a plurality of tanks on a tube trailer coupled to a first control unit, and high pressure buffer storage having predefined capacity coupled to a second control unit and the first tanks by a pressure control valve and the first control unit, and at least one compressor. The refueling station is operated at different modes depending on a state of the refueling station at the beginning of each operational mode. The refueling system is assessed at the end of each operational mode to identify the state of the system and select a next mode of operation. The operational modes include consolidating hydrogen, or any gaseous fuel, within the tubes mounted on the trailer.

  16. Support services to refuelling exploitation; Servicios de apoyo a explotacion en recarga

    Energy Technology Data Exchange (ETDEWEB)

    Castineira, M; Cortes, M.; Rayo, A.

    2010-07-01

    The refuelling period in nuclear power stations is very important due to the need to optimise its duration, large volumes of work and resources that have to be planned and coordinated and their impact on the subsequent operating cycle. Empresarios Agrupados has a permanent organisation, with specialised resources and extensive availability of human resources. (Author)

  17. GUIDELINES FOR IMPLEMENTATION OF AN ADVANCED OUTAGE CONTROL CENTER TO IMPROVE OUTAGE COORDINATION, PROBLEM RESOLUTION, AND OUTAGE RISK MANAGEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Germain, Shawn St; Farris, Ronald; Whaley, April M; Medema, Heather; Gertman, David

    2014-09-01

    This research effort is a part of the Light-Water Reactor Sustainability (LWRS) Program, which is a research and development (R&D) program sponsored by Department of Energy (DOE) and performed in close collaboration with industry R&D programs that provide the technical foundations for licensing and managing the long-term, safe, and economical operation of current nuclear power plants. The LWRS program serves to help the U.S. nuclear industry adopt new technologies and engineering solutions that facilitate the continued safe operation of the plants and extension of the current operating licenses. Managing NPP outages is a complex and difficult task due to the large number of maintenance and repair activities that are accomplished in a short period of time. During an outage, the outage control center (OCC) is the temporary command center for outage managers and provides several critical functions for the successful execution of the outage schedule. Essentially, the OCC functions to facilitate information inflow, assist outage management in processing information, and to facilitate the dissemination of information to stakeholders. Currently, outage management activities primarily rely on telephone communication, face to face reports of status, and periodic briefings in the OCC. It is a difficult task to maintain current the information related to outage progress and discovered conditions. Several advanced communication and collaboration technologies have shown promise for facilitating the information flow into, across, and out of the OCC. The use of these technologies will allow information to be shared electronically, providing greater amounts of real-time information to the decision makers and allowing OCC coordinators to meet with supporting staff remotely. Passively monitoring status electronically through advances in the areas of mobile worker technologies, computer-based procedures, and automated work packages will reduce the current reliance on manually

  18. Hydrogen Production for Refuelling Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hulteberg, Christian; Aagesen, Diane (Intelligent Energy, Long Beach, CA (United States))

    2009-08-15

    The aim of this work is to support the development of a high-profile demonstration of hydrogen generation technologies in a Swedish context. The overall objective of the demonstration is to deploy a reforming based hydrogen refilling station along the Swedish west coast; intermediate to the Malmoe refuelling station and planned stations in Goeteborg. In this way, the Norwegian hydrogen highway will be extended through the south of Sweden and down into Denmark. The aim of the project's first phase, where this constitutes the final report, was to demonstrate the ability to operate the IE reforming system on the E.On/SGC site-specific fuel. During the project, a preliminary system design has been developed, based on IE's proprietary reformer. The system has been operated at pressure, to ensure a stable operation of the downstream PSA; which has been operated without problems and with the expected hydrogen purity and recovery. The safe operation of the proposed and tested system was first evaluated in a preliminary risk assessment, as well as a full HazOp analysis. A thorough economic modelling has been performed on the viability of owning and operating this kind of hydrogen generation equipment. The evaluation has been performed from an on-site operation of such a unit in a refuelling context. The general conclusion from this modelling is that there are several parameters that influence the potential of an investment in a Hestia hydrogen generator. The sales price of the hydrogen is one of the major drivers of profitability. Another important factor is the throughput of the unit, more important than efficiency and utilization. Varying all of the parameters simultaneously introduce larger variations in the NPV, but 60% of the simulations are in the USD 90 000 to USD 180 000 interval. The chosen intervals for the parameters were: Hydrogen Sales Price (USD 5 - USD 7 per kg); Investment Cost (USD 70 000 - USD 130 000 per unit); Throughput (20 - 30 kg

  19. Effectiveness of cell outage compensation in LTE networks

    NARCIS (Netherlands)

    Amirijoo, M.; Jorguseski, L.; Litjens, R.; Nascimento, R.

    2011-01-01

    Cell outage management is a self-healing functionality in future mobile cellular networks, aiming to automatically detect cell or site level outages (cell outage detection) as well as to mitigate as much as possible the caused degradation of coverage, capacity and/or service quality (cell outage com

  20. Power Outage, Business Continuity and Businesses' Choices of Power Outage Mitigation Measures

    Directory of Open Access Journals (Sweden)

    Ali Asgary

    2011-01-01

    Full Text Available Problem statement: Power outage has been mentioned as one of the most experienced and perceived risks by various types of businesses and organizations. Thus, reducing the impacts of power outage has become a key agenda in business continuity planning. Back-up or stand-by generators are among the most well known measures taken by power consumers to tackle the power outage problem. Approach: A survey was conducted to understand various aspects of power outage and the impacts of power outrage on businesses. In addition a choice experiment method was used to derive businesses’ preferences for different power outage mitigation measures that would have a range of prices, space requirements, air and noise pollution as well as mobility attributes using a sample of Canadian businesses located in the . Sample was drawn from businesses operating in the Greater Toronto Area (GTA and surrounding communities in Ontario, Canada. Results: It was found that majority of businesses have experienced and unconvinced by power outage and consider it to be a major risk to their operations. Production loss, data loss, damage to equipment and loss of lighting are the most significant sources for inconveniences caused by the power outages. It was found that a considerable number of businesses have not taken appropriate measures to mitigate this risk. Estimations from the responses revealed that sample businesses had a positive willingness to pay for power outage reduction and that businesses prefer power outage mitigation measures that are least costly, have low levels of air and noise pollution and occupy smaller spaces respectively. Conclusion: An uninterrupted power supply is an important element of business continuity in today’s business world. Although many businesses are not fully prepared against power outages, they are willing to pay for low cost and low pollution power outage mitigation measures.

  1. Optimization of hydrogen vehicle refueling via dynamic simulation

    DEFF Research Database (Denmark)

    Rothuizen, Erasmus Damgaard; Mérida, W.; Rokni, Masoud

    2013-01-01

    A dynamic model has been developed to analyze and optimize the thermodynamics and design of hydrogen refueling stations. The model is based on Dymola software and incorporates discrete components. Two refueling station designs were simulated and compared. The modeling results indicate that pressure...... loss in the vehicle's storage system is one of the main factors determining the mass flow and peak cooling requirements of the refueling process. The design of the refueling station does not influence the refueling of the vehicle when the requirements of the technical information report J2601 from...

  2. 30 CFR 56.7804 - Refueling.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refueling. 56.7804 Section 56.7804 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Drilling and Rotary Jet...

  3. 30 CFR 57.7804 - Refueling.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Refueling. 57.7804 Section 57.7804 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Drilling and Rotary Jet...

  4. Contingency Analysis of Cascading Line Outage Events

    Energy Technology Data Exchange (ETDEWEB)

    Thomas L Baldwin; Magdy S Tawfik; Miles McQueen

    2011-03-01

    As the US power systems continue to increase in size and complexity, including the growth of smart grids, larger blackouts due to cascading outages become more likely. Grid congestion is often associated with a cascading collapse leading to a major blackout. Such a collapse is characterized by a self-sustaining sequence of line outages followed by a topology breakup of the network. This paper addresses the implementation and testing of a process for N-k contingency analysis and sequential cascading outage simulation in order to identify potential cascading modes. A modeling approach described in this paper offers a unique capability to identify initiating events that may lead to cascading outages. It predicts the development of cascading events by identifying and visualizing potential cascading tiers. The proposed approach was implemented using a 328-bus simplified SERC power system network. The results of the study indicate that initiating events and possible cascading chains may be identified, ranked and visualized. This approach may be used to improve the reliability of a transmission grid and reduce its vulnerability to cascading outages.

  5. Improving Hurricane Power Outage Prediction Models Through the Inclusion of Local Environmental Factors.

    Science.gov (United States)

    McRoberts, D Brent; Quiring, Steven M; Guikema, Seth D

    2016-10-25

    Tropical cyclones can significantly damage the electrical power system, so an accurate spatiotemporal forecast of outages prior to landfall can help utilities to optimize the power restoration process. The purpose of this article is to enhance the predictive accuracy of the Spatially Generalized Hurricane Outage Prediction Model (SGHOPM) developed by Guikema et al. (2014). In this version of the SGHOPM, we introduce a new two-step prediction procedure and increase the number of predictor variables. The first model step predicts whether or not outages will occur in each location and the second step predicts the number of outages. The SGHOPM environmental variables of Guikema et al. (2014) were limited to the wind characteristics (speed and duration of strong winds) of the tropical cyclones. This version of the model adds elevation, land cover, soil, precipitation, and vegetation characteristics in each location. Our results demonstrate that the use of a new two-step outage prediction model and the inclusion of these additional environmental variables increase the overall accuracy of the SGHOPM by approximately 17%.

  6. AHTR Refueling Systems and Process Description

    Energy Technology Data Exchange (ETDEWEB)

    Varma, V.K.; Holcomb, D.E.; Bradley, E.C.; Zaharia, N.M.; Cooper, E.J.

    2012-07-15

    The Advanced High-Temperature Reactor (AHTR) is a design concept for a central station-type [1500 MW(e)] Fluoride salt–cooled High-temperature Reactor (FHR) that is currently undergoing development by Oak Ridge National Laboratory for the US. Department of Energy, Office of Nuclear Energy’s Advanced Reactor Concepts program. FHRs, by definition, feature low-pressure liquid fluoride salt cooling, coated-particle fuel, a high-temperature power cycle, and fully passive decay heat rejection. The overall goal of the AHTR development program is to demonstrate the technical feasibility of FHRs as low-cost, large-size power producers while maintaining full passive safety. The AHTR is approaching a preconceptual level of maturity. An initial integrated layout of its major systems, structures, and components (SSCs), and an initial, high-level sequence of operations necessary for constructing and operating the plant is nearing completion. An overview of the current status of the AHTR concept has been recently published [1], and a report providing a more detailed overview of the AHTR structures and mechanical systems is currently in preparation. This report documents the refueling components and processes envisioned at this early development phase. The report is limited to the refueling aspects of the AHTR and does not include overall reactor or power plant design information. The report, however, does include a description of the materials envisioned for the various components and the instrumentation necessary to control the refueling process. The report begins with an overview of the refueling strategy. Next a mechanical description of the AHTR fuel assemblies and core is provided. The reactor vessel upper assemblies are then described. Following this the refueling path structures and the refueling mechanisms and components are described. The sequence of operations necessary to fuel and defuel the reactor is then discussed. The report concludes with a discussion of the

  7. AHTR Refueling Systems and Process Description

    Energy Technology Data Exchange (ETDEWEB)

    Varma, Venugopal Koikal [ORNL; Holcomb, David Eugene [ORNL; Bradley, Eric Craig [ORNL; Zaharia, Nathaniel M [ORNL; Cooper, Eliott J [ORNL

    2012-07-01

    The Advanced High-Temperature Reactor (AHTR) is a design concept for a central station-type [1500 MW(e)] Fluoride salt-cooled High-temperature Reactor (FHR) that is currently undergoing development by Oak Ridge National Laboratory for the US. Department of Energy, Office of Nuclear Energy's Advanced Reactor Concepts program. FHRs, by definition, feature low-pressure liquid fluoride salt cooling, coated-particle fuel, a high-temperature power cycle, and fully passive decay heat rejection. The overall goal of the AHTR development program is to demonstrate the technical feasibility of FHRs as low-cost, large-size power producers while maintaining full passive safety. The AHTR is approaching a preconceptual level of maturity. An initial integrated layout of its major systems, structures, and components (SSCs), and an initial, high-level sequence of operations necessary for constructing and operating the plant is nearing completion. An overview of the current status of the AHTR concept has been recently published and a report providing a more detailed overview of the AHTR structures and mechanical systems is currently in preparation. This report documents the refueling components and processes envisioned at this early development phase. The report is limited to the refueling aspects of the AHTR and does not include overall reactor or power plant design information. The report, however, does include a description of the materials envisioned for the various components and the instrumentation necessary to control the refueling process. The report begins with an overview of the refueling strategy. Next a mechanical description of the AHTR fuel assemblies and core is provided. The reactor vessel upper assemblies are then described. Following this the refueling path structures and the refueling mechanisms and components are described. The sequence of operations necessary to fuel and defuel the reactor is then discussed. The report concludes with a discussion of the

  8. Secrecy Outage Capacity of Fading Channels

    CERN Document Server

    Gungor, Onur; Koksal, C Emre; Gamal, Hesham El; Shroff, Ness B

    2011-01-01

    This paper considers point to point secure communication over flat fading channels under an outage constraint. More specifically, we extend the definition of outage capacity to account for the secrecy constraint and obtain sharp characterizations of the corresponding fundamental limits under two different assumptions on the transmitter CSI (Channel state information). First, we find the outage secrecy capacity assuming that the transmitter has perfect knowledge of the legitimate and eavesdropper channel gains. In this scenario, the capacity achieving scheme relies on opportunistically exchanging private keys between the legitimate nodes. These keys are stored in a key buffer and later used to secure delay sensitive data using the Vernam's one time pad technique. We then extend our results to the more practical scenario where the transmitter is assumed to know only the legitimate channel gain. Here, our achievability arguments rely on privacy amplification techniques to generate secret key bits. In the two cas...

  9. Benchmark Report on Key Outage Attributes: An Analysis of Outage Improvement Opportunities and Priorities

    Energy Technology Data Exchange (ETDEWEB)

    Germain, Shawn St. [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Farris, Ronald [Idaho National Laboratory (INL), Idaho Falls, ID (United States)

    2014-09-01

    Advanced Outage Control Center (AOCC), is a multi-year pilot project targeted at Nuclear Power Plant (NPP) outage improvement. The purpose of this pilot project is to improve management of NPP outages through the development of an AOCC that is specifically designed to maximize the usefulness of communication and collaboration technologies for outage coordination and problem resolution activities. This report documents the results of a benchmarking effort to evaluate the transferability of technologies demonstrated at Idaho National Laboratory and the primary pilot project partner, Palo Verde Nuclear Generating Station. The initial assumption for this pilot project was that NPPs generally do not take advantage of advanced technology to support outage management activities. Several researchers involved in this pilot project have commercial NPP experience and believed that very little technology has been applied towards outage communication and collaboration. To verify that the technology options researched and demonstrated through this pilot project would in fact have broad application for the US commercial nuclear fleet, and to look for additional outage management best practices, LWRS program researchers visited several additional nuclear facilities.

  10. Outage managment and health physics issue, 2008

    Energy Technology Data Exchange (ETDEWEB)

    Agnihotri, Newal (ed.)

    2008-05-15

    The focus of the May-June issue is on outage management and health physics. Major articles include: Outage optimization initiatives, by George B. Beam, AREVA NP, Inc.; New plant based on excellent track records, by Jim Scarola, Progress Energy; Meeting customer needs and providing environmental benefits, by Peter S. Hastings, Duke Energy; Plants with 3-D design, by Jack A. Bailey, Tennessee Valley Authority; and Highest quality with exceptional planning, by Jason A. Walls, Duke Energy. Industry innovation articles include: Integrated exposure reduction plan, by Ed Wolfe, Exelon; Performance-based radiation worker training, by Joe Giuffre and Timothy Vriezerma, American Electric Power.

  11. Guidelines for Implementation of an Advanced Outage Control Center to Improve Outage Coordination, Problem Resolution, and Outage Risk Management

    Energy Technology Data Exchange (ETDEWEB)

    St. Germain, Shawn W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Farris, Ronald K. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Whaley, April M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Medema, Heather D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Gertman, David I. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-09-01

    This research effort is a part of the Light-Water Reactor Sustainability (LWRS) Program, which is a research and development (R&D) program sponsored by Department of Energy (DOE) and performed in close collaboration with industry R&D programs that provide the technical foundations for licensing and managing the long-term, safe, and economical operation of current nuclear power plants. The LWRS program serves to help the U.S. nuclear industry adopt new technologies and engineering solutions that facilitate the continued safe operation of the plants and extension of the current operating licenses. The purpose of this research is to improve management of nuclear power plant (NPP) outages through the development of an advanced outage control center (AOCC) that is specifically designed to maximize the usefulness of communication and collaboration technologies for outage coordination and problem resolution activities. This technical report for industry implementation outlines methods and considerations for the establishment of an AOCC. This report provides a process for implementation of a change management plan, evaluation of current outage processes, the selection of technology, and guidance for the implementation of the selected technology. Methods are presented for both adoption of technologies within an existing OCC and for a complete OCC replacement, including human factors considerations for OCC design and setup.

  12. Standardized Technical Data Survey (STDS) for Aerial Refueling

    Science.gov (United States)

    2016-09-06

    for safe aerial refueling. The international document for aerial refueling procedures is ATP 3.3.4.2 (formerly ATP -56) Each individual tanker and...receiver aircraft combination listed in ATP 3.3.4.2. should have been fully cleared for aerial refueling operations for one of three different categories...of clearance: (1) Urgent; (2) Partial; and (3) Full. These categories are defined in ATP 3.3.4.2.. An example of a category 3, full clearance would be

  13. Cell outage compensation in LTE networks: Algorithms and performance assessment

    NARCIS (Netherlands)

    Amirijoo, M.; Jorguseski, L.; Litjens, R.; Schmelz, L.C.

    2011-01-01

    Cell outage compensation is a self-healing function and as such part of the Self-Organising Networks concept for mobile wireless networks. It aims at mitigating the degradation of coverage, capacity and service quality caused by a cell or site level outage. Upon detection of such an outage, cell out

  14. Power outages, power externalities, and baby booms.

    Science.gov (United States)

    Burlando, Alfredo

    2014-08-01

    Determining whether power outages have significant fertility effects is an important policy question in developing countries, where blackouts are common and modern forms of family planning are scarce. Using birth records from Zanzibar, this study shows that a month-long blackout in 2008 caused a significant increase in the number of births 8 to 10 months later. The increase was similar across villages that had electricity, regardless of the level of electrification; villages with no electricity connections saw no changes in birth numbers. The large fertility increase in communities with very low levels of electricity suggests that the outage affected the fertility of households not connected to the grid through some spillover effect. Whether the baby boom is likely to translate to a permanent increase in the population remains unclear, but this article highlights an important hidden consequence of power instability in developing countries. It also suggests that electricity imposes significant externality effects on rural populations that have little exposure to it.

  15. Outage management and health physics issue, 2006

    Energy Technology Data Exchange (ETDEWEB)

    Agnihotri, Newal (ed.)

    2006-05-15

    The focus of the May-June issue is on outage management and health physics. Major articles/reports in this issue include: A design with experience for the U.S., by Michael J. Wallace, Constellation Generation Group; Hope to be among the first, by Randy Hutchinson, Entergy Nuclear; Plans to file COLs in 2008, by Garry Miller, Progress Energy; Evolution of ICRP's recommendations, by Lars-Erik Holm, ICRP; European network on education and training in radiological protection, by Michele Coeck, SCK-CEN, Belgium; Outage managment: an important tool for improving nuclear power plant performance, by Thomas Mazour and Jiri Mandula, IAEA, Austria; and Plant profile: Exploring new paths to excellence, by Anne Thomas, Exelon Nuclear.

  16. Advanced Outage and Control Center: Strategies for Nuclear Plant Outage Work Status Capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Gregory Weatherby

    2012-05-01

    The research effort is a part of the Light Water Reactor Sustainability (LWRS) Program. LWRS is a research and development program sponsored by the Department of Energy, performed in close collaboration with industry to provide the technical foundations for licensing and managing the long-term, safe and economical operation of current nuclear power plants. The LWRS Program serves to help the US nuclear industry adopt new technologies and engineering solutions that facilitate the continued safe operation of the plants and extension of the current operating licenses. The Outage Control Center (OCC) Pilot Project was directed at carrying out the applied research for development and pilot of technology designed to enhance safe outage and maintenance operations, improve human performance and reliability, increase overall operational efficiency, and improve plant status control. Plant outage management is a high priority concern for the nuclear industry from cost and safety perspectives. Unfortunately, many of the underlying technologies supporting outage control are the same as those used in the 1980’s. They depend heavily upon large teams of staff, multiple work and coordination locations, and manual administrative actions that require large amounts of paper. Previous work in human reliability analysis suggests that many repetitive tasks, including paper work tasks, may have a failure rate of 1.0E-3 or higher (Gertman, 1996). With between 10,000 and 45,000 subtasks being performed during an outage (Gomes, 1996), the opportunity for human error of some consequence is a realistic concern. Although a number of factors exist that can make these errors recoverable, reducing and effectively coordinating the sheer number of tasks to be performed, particularly those that are error prone, has the potential to enhance outage efficiency and safety. Additionally, outage management requires precise coordination of work groups that do not always share similar objectives. Outage

  17. Transmission network expansion planning under deliberate outages

    Energy Technology Data Exchange (ETDEWEB)

    Alguacil, Natalia; Carrion, Miguel; Arroyo, Jose Manuel [E.T.S. de Ingenieros Industriales, Universidad de Castilla - La Mancha, Campus Universitario s/n, 13071 Ciudad Real (Spain)

    2009-10-15

    The reasons why the transmission network is a potentially attractive target for deliberate outages are twofold: (i) its crucial importance as a critical infrastructure for the society welfare, and (ii) its high level of vulnerability due to the current operation close to its static and dynamic limits. This new context where destructive agents come into play has been recognized by several agencies in Europe and North America, and various initiatives have been launched worldwide in order to assess and mitigate the vulnerability of transmission. Within this framework, this paper proposes the reinforcement and expansion of the transmission network as a way of mitigating the impact of increasingly plausible deliberate outages. The network planner selects the new lines to be built accounting not only for economic issues, as traditionally done, but also for the vulnerability of the transmission network against a set of credible intentional outages. The resulting vulnerability- and economic-constrained transmission expansion planning problem is formulated as a mixed-integer linear program. A number of case studies numerically illustrate the tradeoff between economic- and vulnerability-related issues and its impact on the expansion plans. In addition, we compare the results with those achieved by a traditional expansion planning model based on cost minimization. (author)

  18. A guideline for optimizing outage management of Eskom's transmission network / Michelle de Haan

    OpenAIRE

    de Haan, Michelle

    2012-01-01

    A streamlined process is needed to optimize the outage management of the Eskom transmission power system, as well as a ranking system in order to determine the best window of opportunity for an outage to occur thus positively impacting on Eskom‘s asset management. The outage data captured between 2007 and 2011 was analysed for all cancelled, turned down and completed outages. This data indicated that there were 19 902 completed outages, 5 312 cancelled outages and 1 889 turned down outages...

  19. Neutronic characteristics of an OTTO refueling PBMR

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Hoai Nam, E-mail: nam@nephy.chalmers.se [Chalmers University of Technology, Department of Applied Physics, Division of Nuclear Engineering, SE-412 96 Gothenburg (Sweden); Hoang, Van Khanh [Institute for Nuclear Science and Technology, 179 Hoang Quoc Viet str., Hanoi (Viet Nam)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Neutronic characteristics were analyzed for an OTTO refueling PBMR. Black-Right-Pointing-Pointer The core uses newly designed fuel pebbles with Gd{sub 2}O{sub 3} as burnable poison. Black-Right-Pointing-Pointer The neutronic characteristics are comparable with a reference multi-pass scheme. Black-Right-Pointing-Pointer The average discharged burnup is 21% lower than that of the multi-pass scheme. - Abstract: Neutronic characteristics were investigated for a once-through-then-out (OTTO) refueling scheme based on the 400 MWt pebble bed modular reactor (PBMR) and compared with that of a reference multi-pass scheme. The core was loaded with new fuel pebbles which were designed with Gd{sub 2}O{sub 3} particles to flatten the axial power profile. The Gd{sub 2}O{sub 3} design was considered in a multi-parameter optimization to maximize the average discharged burnup while maintaining a limited power peak and ensuring core criticality. The results show that the OTTO scheme using the new fuel pebbles can achieve the maximum average discharged burnup of about 75 GWd/t, at which the core neutronic characteristics are comparable with that of the reference multi-pass scheme. This means that the efficiency of fuel utilization of the OTTO scheme is about 21% less than that of the multi-pass scheme (95 GWd/t).

  20. Forecasting New Hampshire Power Outages through the Analysis of Weather Station Observations

    Science.gov (United States)

    Fessenden, Ross T.

    Eversource Energy, formerly Public Service of New Hampshire (PSNH), has worked closely with Plymouth State University (PSU) in the past, and present, to better predict weather-related power outage events and maximize the efficiency with which Eversource responds to them. This research paired weather data from thirteen stations throughout New Hampshire, Vermont, and Massachusetts with Eversource Trouble Report and Unsatisfactory Performance of Equipment Report (TRUPER) data in an effort to quantify weather situations that lead to power outages. The ultimate goal involved developing a predictive model that uses weather data to forecast the magnitude of power outages. The study focused on the Eversource Western/Central service territory and utilized data from 2006-2010. The first four years, 2006-2009, were analyzed using Classification and Regression Tree (CART) statistical analysis. The results of this CART analysis trained a predictive model, while the fifth year, 2010, served as the testing set for the predictive model. To conduct the statistical analysis, a database was created pairing TRUPER reports with the closest available hourly weather observations. The database included nine weather variables matched with three variables from the TRUPER data: 1) customers, 2) customer minutes, and 3) outage duration. While the entire Eversource service territory saw 91,286 TRUPERs from 2006-2010, the Western/Central service territory, the focus of this study, accounted for 29,430. Before conducting the CART analysis, correlations between single weather variables and TRUPER data were calculated and, in general, proved xi weak. In addition to analyzing the complete four-year training data set, many portions/variations of the data set were analyzed. The analyses included a yearly analysis, time lag analysis, cold/warm-season analysis, and a single-station analysis. Although individual years and smaller data sets showed moderately higher correlations between weather and outage

  1. The effect of power outages and cheap talk on willingness to pay to reduce outages

    OpenAIRE

    Carlsson, Fredrik; Martinsson, Peter; AKAY Alpaslan

    2009-01-01

    Using an open-ended contingent valuation survey, we analyze how (i) experience of a power outage due to one of the worst storms ever to hit Sweden and (ii) a cheap talk script affect respondents' WTP to avoid power outages. Experience significantly increases and a cheap talk script decreases the proportion of respondents with zero WTP. There is no significant effect in either case on stated WTP conditional on a positive WTP. The paper concludes with a discussion on the use of valuation studie...

  2. MIMO ARQ with Multi-bit Feedback: Outage Analysis

    CERN Document Server

    Nguyen, Khoa D; Fabregas, Albert Guillen i; Letzepis, Nick

    2010-01-01

    We study the asymptotic outage performance of incremental redundancy automatic repeat request (INR-ARQ) transmission over the multiple-input multiple-output (MIMO) block-fading channels with discrete input constellations. We first show that transmission with random codes using a discrete signal constellation across all transmit antennas achieves the optimal outage diversity given by the Singleton bound. We then analyze the optimal SNR-exponent and outage diversity of INR-ARQ transmission over the MIMO block-fading channel. We show that a significant gain in outage diversity is obtained by providing more than one bit feedback at each ARQ round. Thus, the outage performance of INR-ARQ transmission can be remarkably improved with minimal additional overhead. A suboptimal feedback and power adaptation rule, which achieves the optimal outage diversity, is proposed for MIMO INR-ARQ, demonstrating the benefits provided by multi-bit feedback.

  3. Hydrogen Refuelling Station Hamburg HafenCity

    Energy Technology Data Exchange (ETDEWEB)

    Hustadt, Daniel [Vattenfall Europe Innovation GmbH (Germany)

    2010-07-01

    Decoupling the growing road traffic and the related greenhouse gas emissions demand a major effort by research, OEMs as well as oil and energy companies. Above all the reduction of CO2-emissions is a growing need for climate protection. Bio fuels can help to reach those targets, however the available sources are not enough to guarantee a sustainable supply. Battery Electric Vehicles are today limited technically with regards to range and weight and will most likely be used in metropolitan regions. In this project the necessary infrastructure to refuel buses and cars of a bigger fleet will be installed. Doing so the prerequisite for using fuel cell based cars and buses as an alternative way of mobility is developed. The capability of new components for the productions, storage and distribution of larger amounts of hydrogen is shown. Additionally still existing potential optimizing on a technical and operational level shall be made available. (orig.)

  4. Minimizing forced outage risk in generator bidding

    Science.gov (United States)

    Das, Dibyendu

    Competition in power markets has exposed the participating companies to physical and financial uncertainties. Generator companies bid to supply power in a day-ahead market. Once their bids are accepted by the ISO they are bound to supply power. A random outage after acceptance of bids forces a generator to buy power from the expensive real-time hourly spot market and sell to the ISO at the set day-ahead market clearing price, incurring losses. A risk management technique is developed to assess this financial risk associated with forced outages of generators and then minimize it. This work presents a risk assessment module which measures the financial risk of generators bidding in an open market for different bidding scenarios. The day-ahead power market auction is modeled using a Unit Commitment algorithm and a combination of Normal and Cauchy distributions generate the real time hourly spot market. Risk profiles are derived and VaRs are calculated at 98 percent confidence level as a measure of financial risk. Risk Profiles and VaRs help the generators to analyze the forced outage risk and different factors affecting it. The VaRs and the estimated total earning for different bidding scenarios are used to develop a risk minimization module. This module will develop a bidding strategy of the generator company such that its estimated total earning is maximized keeping the VaR below a tolerable limit. This general framework of a risk management technique for the generating companies bidding in competitive day-ahead market can also help them in decisions related to building new generators.

  5. Plant maintenance and outage management issue, 2005

    Energy Technology Data Exchange (ETDEWEB)

    Agnihotri, Newal (ed.)

    2005-01-15

    The focus of the January-February issue is on plant maintenance and outage managment. Major articles/reports in this issue include: Dawn of a new era, by Joe Colvin, Nuclear Energy Institute (NEI); Plant profile: Beloyarsk NPP, Russia, by Nikolai Oshkanov, Beloyarsk NPP, Russia; Improving economic performance, by R. Spiegelberg-Planner, John De Mella, and Marius Condu, IAEA; A model for improving performance, by Pet Karns, MRO Software; ASME codes and standards, by Shannon Burke, ASME International; and, Refurbishment programs, by Craig S. Irish, Nuclear Logistics, Inc.

  6. Economic costs of electrical system instability and power outages caused by snakes on the Island of Guam

    Science.gov (United States)

    Fritts, T.H.

    2002-01-01

    The Brown Tree Snake, Boiga irregularis, is an introduced species on Guam where it causes frequent electrical power outages. The snake's high abundance, its propensity for climbing, and use of disturbed habitats all contribute to interruption of Guam's electrical service and the activities that depend on electrical power. Snakes have caused more than 1600 power outages in the 20-yr period of 1978-1997 and most recently nearly 200 outages per year. Single outages spanning the entire island and lasting 8 or more hours are estimated to cost in excess of $3,000,000 in lost productivity, but the costs of outages that involve only parts of the island or those of shorter durations are more difficult to quantify. Costs to the island's economy have exceeded $4.5 M per year over a 7-yr period without considering repair costs, damage to electrical equipment, and lost revenues. Snakes pose the greatest problem on high voltage transmission lines, on transformers, and inside electrical substations.

  7. Regional Consumer Hydrogen Demand and Optimal Hydrogen Refueling Station Siting

    Energy Technology Data Exchange (ETDEWEB)

    Melendez, M.; Milbrandt, A.

    2008-04-01

    Using a GIS approach to spatially analyze key attributes affecting hydrogen market transformation, this study proposes hypothetical hydrogen refueling station locations in select subregions to demonstrate a method for determining station locations based on geographic criteria.

  8. Outage analysis of blind cooperative diversity

    KAUST Repository

    Tourki, Kamel

    2011-06-06

    Mobile users with single antennas can still take advantage of spatial diversity through cooperative space-time-encoded transmission. In this paper, we considered a scheme in which a relay chooses to cooperate only if its source-relay channel is of an acceptable quality, and we evaluate the usefulness of relaying when the source acts blindly and ignores the decision of the relays whether they may cooperate or not. In our study, we consider the regenerative relays in which the decisions to cooperate are based on a targeted end-to-end data rate R. We derived the end-to-end outage probability for a transmission rate R and a code rate ρ and look at a power allocation strategy between the source and the relays in order to minimize the end-to-end outage probability at the destination for high signal-to-noise ratio, by using the golden section search method. Performance results show that the computer simulations-based results coincide with our analytical results. Copyright © 2011 John Wiley & Sons, Ltd.

  9. Distribution of time between unscheduled outages

    Energy Technology Data Exchange (ETDEWEB)

    Jaech, J.L.; Burke, R.C.

    1963-01-02

    A study is in progress in which reactor operations will be simulated on the computer, the primary purpose being to evaluate the costs associated with various administrative alternatives which may be followed in conducting the overall operation, in addition to defining how operational costs are affected by such things as changes in fuel quality. The problem is complicated by the fact that the operation of the reactors is largely affected by random occurrences; no one can predict exactly when a tube will leak, or when a rupture will occur. Therefore, basic to the study is a probabilistic function, or set of functions, which govern the random aspects of reactor outages, and which can be used in the simulation study to generate reactor outages. This report is concerned with the derivation of such probabilistic functions. Although derived specifically for the simulation study, they are deemed of sufficient interest to warrant a separate report. Similar documents will be issued from time to time as the study progresses, and as results are found which are considered worthy of reporting prior to completion of the study.

  10. Connecting Transitions in Galaxy Properties to Refueling

    CERN Document Server

    Kannappan, Sheila J; Eckert, Kathleen D; Moffett, Amanda J; Wei, Lisa H; Pisano, D J; Baker, Andrew J; Vogel, Stuart N; Fabricant, Daniel G; Laine, Seppo; Norris, Mark A; Jogee, Shardha; Lepore, Natasha; Hough, Loren E; Weinberg-Wolf, Jennifer

    2013-01-01

    We relate transitions in galaxy structure and gas content to refueling, here defined to include both the external gas accretion and the internal gas processing needed to renew reservoirs for star formation. We analyze two z=0 data sets: a high-quality ~200-galaxy sample (the Nearby Field Galaxy Survey, data release herein) and a volume-limited ~3000-galaxy sample with reprocessed archival data. Both reach down to baryonic masses ~10^9Msun and span void-to-cluster environments. Two mass-dependent transitions are evident: (i) below the "gas-richness threshold" scale (V~125km/s), gas-dominated quasi-bulgeless Sd--Im galaxies become numerically dominant, while (ii) above the "bimodality" scale (V~200km/s), gas-starved E/S0s become the norm. Notwithstanding these transitions, galaxy mass (or V as its proxy) is a poor predictor of gas-to-stellar mass ratio M_gas/M_*. Instead, M_gas/M_* correlates well with the ratio of a galaxy's stellar mass formed in the last Gyr to its preexisting stellar mass, such that the two...

  11. REFUEL: an EU road map for biofuels

    Energy Technology Data Exchange (ETDEWEB)

    Londo, M.; Deurwarder, E.; Lensink, S. (and others)

    2007-05-15

    A successful mid-term development of biofuels calls for a robust road map. REFUEL assesses inter alia least-cost biofuel chain options, their benefits, outlines the technological, legislative and other developments that should take place, and evaluate different policy strategies for realisation. Some preliminary conclusions of the project are discussed here. There is a significant domestic land potential for energy crops in the EU, which could supply between one quarter and one third of gasoline and diesel demand by 2030 if converted into advanced biofuels. A biomass supply of 8 to 10 EJ of primary energy could be available at costs around or below 3 EURO/GJ. However, the introduction of advanced biofuel options may meet a considerable introductory cost barrier, which will not be overcome when EU policy is oriented to the introduction of biofuels at least cost. Therefore, conventional biodiesel and ethanol may dominate the market for decades to come, unless biofuels incentives are differentiated, e.g. on the basis of the differences in greenhouse gas performance among biofuels.The introduction of advanced biofuels may also be enhanced by creating stepping stones or searching introduction synergies. A stepping stone can be the short-term development of lignocellulosic biomass supply chains for power generation by co-firing; synergies can be found between advanced FT-diesel production and hydrogen production for the fuel cell. (au)

  12. Technology Integration Initiative In Support of Outage Management

    Energy Technology Data Exchange (ETDEWEB)

    Gregory Weatherby; David Gertman

    2012-07-01

    Plant outage management is a high priority concern for the nuclear industry from cost and safety perspectives. Often, command and control during outages is maintained in the outage control center where many of the underlying technologies supporting outage control are the same as those used in the 1980’s. This research reports on the use of advanced integrating software technologies and hand held mobile devices as a means by which to reduce cycle time, improve accuracy, and enhance transparency among outage team members. This paper reports on the first phase of research supported by the DOE Light Water Reactor Sustainability (LWRS) Program that is performed in close collaboration with industry to examine the introduction of newly available technology allowing for safe and efficient outage performance. It is thought that this research will result in: improved resource management among various plant stakeholder groups, reduced paper work, and enhanced overall situation awareness for the outage control center management team. A description of field data collection methods, including personnel interview data, success factors, end-user evaluation and integration of hand held devices in achieving an integrated design are also evaluated. Finally, the necessity of obtaining operations cooperation support in field studies and technology evaluation is acknowledged.

  13. Refuelling stations for hydrogen or reformate gas

    Energy Technology Data Exchange (ETDEWEB)

    Silversand, Fredrik [CATATOR AB, Lund (Sweden)

    2006-02-15

    A prestudy concerning refuelling stations for reformate gas/hydrogen has been performed on the request of Swedish Gas Centre. The plan is to build a small-scale fuel processor for said application during 2006 as a continuation of the RandD programme in the fuel processing area. Catator has designed and evaluated small-scale fuel processors in a series of SGC-projects. The fuel processor system was abbreviated 'Stur-unit' and contained reactors for steam reforming, water-gas shift and preferential oxidation, tied together in a single train unit. The STUR-unit is operated at atmospheric conditions and will produce reformate gas of fuel cell quality (normally less than 20 ppm of CO). Catator has designed and delivered a number of Stur-units ranging from 1 nm{sup 3} to 50 nm{sup 3}/hr of hydrogen. Different fuels have been evaluated, both gases and liquids. Catator has also designed a pressurised system together with Intelligent Energy (abbreviated 'Hestia-unit'). This unit operates at 5-10 bar(a) and utilizes physical purification by means of fast-cycle PSA to provide essential pure hydrogen. Both units have been subjected to successful long-term testing. The hydrogen demand in Malmoe (the proposed location for the refuelling station) is presently low and irregular since only two buses utilize Hythane (a mixture between natural gas and hydrogen) at the moment. The interest for hydrogen and hydrogen containing fuels is, however, expected to increase in a near future. E.ON Gas (the owner of the existing refuelling station) has forwarded a number of specifications for the fuel processor system. The unit shall operate on natural gas and biogas. Bio-derived liquid fuels (bio ethanol and E85 - a mixture between ethanol and gasoline) could also be interesting alternatives. Depending on the low demand for hydrogen (average of about 1 nm{sup 3}/hr), the production capacity can be rather low - 5-10 nm{sup 3}/hr is probably more than enough for the time being

  14. Aerial Refueling Process Rescheduling Under Job Related Disruptions

    Science.gov (United States)

    Kaplan, Sezgin; Rabadi, Ghaith

    2011-01-01

    The Aerial Refueling Scheduling Problem (ARSP) can be defined as determining the refueling completion times for each fighter aircraft (job) on the multiple tankers (machines) to minimize the total weighted tardiness. ARSP assumes that the jobs have different release times and due dates. The ARSP is dynamic environment and unexpected events may occur. In this paper, rescheduling in the aerial refueling process with a time set of jobs will be studied to deal with job related disruptions such as the arrival of new jobs, the departure of an existing job, high deviations in the release times and changes in job priorities. In order to keep the stability and to avoid excessive computation, partial schedule repair algorithm is developed and its preliminary results are presented.

  15. Outage performance of cognitive radio systems with Improper Gaussian signaling

    KAUST Repository

    Amin, Osama

    2015-06-14

    Improper Gaussian signaling has proved its ability to improve the achievable rate of the systems that suffer from interference compared with proper Gaussian signaling. In this paper, we first study impact of improper Gaussian signaling on the performance of the cognitive radio system by analyzing the outage probability of both the primary user (PU) and the secondary user (SU). We derive exact expression of the SU outage probability and upper and lower bounds for the PU outage probability. Then, we design the SU signal by adjusting its transmitted power and the circularity coefficient to minimize the SU outage probability while maintaining a certain PU quality-of-service. Finally, we evaluate the proposed bounds and adaptive algorithms by numerical results.

  16. Distortion outage minimization in Nakagami fading using limited feedback

    National Research Council Canada - National Science Library

    Wang, Chih-Hong; Dey, Subhrakanti

    2011-01-01

    .... The objective of this paper is to design clusterhead transmit power allocation policies to minimize the distortion outage probability at the fusion center, subject to an expected sum transmit power constraint...

  17. Lassoing Line Outages in the Smart Power Grid

    OpenAIRE

    Zhu, Hao; Giannakis, Georgios B.

    2011-01-01

    Fast and accurate unveiling of power line outages is of paramount importance not only for preventing faults that may lead to blackouts, but also for routine monitoring and control tasks of the smart grid, including state estimation and optimal power flow. Existing approaches are either challenged by the \\emph{combinatorial complexity} issues involved, and are thus limited to identifying single- and double-line outages; or, they invoke less pragmatic assumptions such as \\emph{conditionally ind...

  18. Testing of a refuelable zinc/air bus battery

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, J.F.; Fleming, D.; Koopman, R.; Hargrove, D.; Maimoni, A.; Peterman, K.

    1995-02-22

    We report tests of a refuelable zinc/air battery of modular, bipolar-cell design, intended for fleet electric busses and vans. The stack consists of twelve 250-cm{sup 2} cells built of two units: (1) a copper-clad glass-reinforced epoxy board supporting anode and cathode current collectors, and (2) polymer frame providing for air- and electrolyte distribution and zinc fuel storage. The stack was refueled in 4 min. by a hydraulic transfer of zinc particles entrained in solution flow.

  19. The four ``Ps`` of outage management

    Energy Technology Data Exchange (ETDEWEB)

    Kuehn, S.E.

    1996-01-01

    This article describes how planning, partnering, preparation and people prevent poor outage performance. Boasting the best production costs in a decade, the US fleet of nuclear reactors is performing better than ever. Industry wide, production costs fell 7% to $20.02 per net megawatt hour (MWh) and output climbed 3% to 634million MWh. It doesn`t take a nuclear physicists to realize that when base-loaded nuclear units are operated for long periods of time, near their technical potential, costs will fall and relative performance improves. Statistics for 1994 compiled by the Institute of Nuclear Operations (INPO) and the World Association of Nuclear Operators (WANO) showed the industry has steadily improved in most of the 10 industry-recognized categories. In 1994, Unit Capability Factor (the percentage of maximum energy generation a plant can supply to the grid) reached just under 82%, beating the 1995 goal and proving just how far the industry has come (62.7% in 1980) when improving plant operations.

  20. Analysis of the Dependence of Power Outages on Lightning Events within the Ijebu Province, Nigeria

    OpenAIRE

    J.O. Adepitan; E.O. Oladiran

    2012-01-01

    The study aimed at developing a model for lightning-induced outages in Nigeria from results obtained on determining the proportion and rate of lightning-induced outages out of the total power outages experienced in Ijebu province of Nigeria. Power outage records for Ijebu province, comprising Ijebu-Ode and Sagamu areas, Ogun state, Nigeria for the years 2002-2006 were collected from Power Holding Company of Nigeria (PHCN). Unintentional stochastic outages were separated from those due to deli...

  1. Development of an Overview Display to Allow Advanced Outage Control Center Management to Quickly Evaluate Outage Status

    Energy Technology Data Exchange (ETDEWEB)

    St Germain, Shawn Walter [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hugo, Jacques Victor [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-01

    This report describes recent advances made in developing a framework for the design of visual outage information presentation, as well as an overview of the scientific principles that informed the development of the visualizations.

  2. Sample Results from MCU Solids Outage

    Energy Technology Data Exchange (ETDEWEB)

    Peters, T.; Washington, A.; Oji, L.; Coleman, C.; Poirier, M.

    2014-09-22

    Savannah River National Laboratory (SRNL) has received several solid and liquid samples from MCU in an effort to understand and recover from the system outage starting on April 6, 2014. SRNL concludes that the presence of solids in the Salt Solution Feed Tank (SSFT) is the likely root cause for the outage, based upon the following discoveries: A solids sample from the extraction contactor #1 proved to be mostly sodium oxalate; A solids sample from the scrub contactor#1 proved to be mostly sodium oxalate; A solids sample from the Salt Solution Feed Tank (SSFT) proved to be mostly sodium oxalate; An archived sample from Tank 49H taken last year was shown to contain a fine precipitate of sodium oxalate; A solids sample from ; A liquid sample from the SSFT was shown to have elevated levels of oxalate anion compared to the expected concentration in the feed. Visual inspection of the SSFT indicated the presence of precipitated or transferred solids, which were likely also in the Salt Solution Receipt Tank (SSRT). The presence of the solids coupled with agitation performed to maintain feed temperature resulted in oxalate solids migration through the MCU system and caused hydraulic issues that resulted in unplanned phase carryover from the extraction into the scrub, and ultimately the strip contactors. Not only did this carryover result in the Strip Effluent (SE) being pushed out of waste acceptance specification, but it resulted in the deposition of solids into several of the contactors. At the same time, extensive deposits of aluminosilicates were found in the drain tube in the extraction contactor #1. However it is not known at this time how the aluminosilicate solids are related to the oxalate solids. The solids were successfully cleaned out of the MCU system. However, future consideration must be given to the exclusion of oxalate solids into the MCU system. There were 53 recommendations for improving operations recently identified. Some additional considerations or

  3. Uncertainties in explosion risk assessment for a hydrogen refueling station

    NARCIS (Netherlands)

    Ham, J.M.; Maaijer, M. de; Hoogenband, V. van den; Dam, C.E.C.; Weeda, M.; Reijerkerk, J.; Kramer, G.J.

    2011-01-01

    The project “Towards a Hydrogen Refueling Infrastructure for Vehicles” (THRIVE) aimed at the determination of conditions to stimulate the building of a sustainable infrastructure for hydrogen as a car fuel in The Netherlands. Economic scenarios were constructed for the development of such an

  4. Hyapproval : final handbook for approval of hydrogen refuelling stations

    NARCIS (Netherlands)

    Wurster, R.; Landinger, H.; Machens, C.; Allidières, L.; Molag, M.; Barron, J.; Reijalt, M.; Hill, H.J.

    2006-01-01

    HyApproval is an EC co-financed Specific Targeted Research Project (STREP) to develop a Handbook facilitating the approval of Hydrogen Refuelling Stations (HRS). The project, started in October 2005, will be performed over 24 months by a balanced partnership including 25 partners from industry, SMEs

  5. Cold power plant based on the cryogenic refueling tank

    Directory of Open Access Journals (Sweden)

    A. I. Dovgjallo

    2014-01-01

    Full Text Available The paper evaluates the possibility to use a tank with cryogenic refueling as a part of the autonomous complex employing the liquefied natural gas. A cryogenic refueling tank-based installation to utilize a low-grade heat has been designed. During its use extra electric power is generated. To assess a performance capability, the proposed installation calculations have been made for different end pressures in cryogenic refueling tank. In all embodiments, the mass of cryogenic refilled is 866 kg. Depending on the pressure an amount of extra electric power is produced owing to utilizing a low temperature potential of LNG. New values, such as the specific amount of extra energy are introduced. These values allow objective assessment of the potential for extra energy when using the cryogenic products with their subsequent regasification in cryogenic refueling tank taking into consideration the operational constraints and the working fluid flow.A cold energy power plant has been also designed to refuel vehicles with the natural gas. In this paper the turbines with desirable expansion ratio to generate the maximum possible amount of power were selected in an optimal way. The optimum degree of expansion for the first turbine in the first loop will be т = 8.8; for the second turbine in the first loop т = 10; turbines for the second loop т = 3.9. The total amount of generated electric power will be 3725.22 kW•h for 225 min. The action time of cold energy power plant, including the time of methane gasification in cryogenic refueling tank, time of refueling vehicles, and time of electricity generation will be 24 hours. The economic assessment of cold energy power plant has shown that the payback period is 3.4 years.Thus, the performance evaluation by the temperature and pressure levels eliminates the possibility for forming the hydrates.So the calculations have shown that research in the development of power plants looks promising as well as allow you

  6. Optimal Facility Location Model Based on Genetic Simulated Annealing Algorithm for Siting Urban Refueling Stations

    Directory of Open Access Journals (Sweden)

    Dawei Chen

    2015-01-01

    Full Text Available This paper analyzes the impact factors and principles of siting urban refueling stations and proposes a three-stage method. The main objective of the method is to minimize refueling vehicles’ detour time. The first stage aims at identifying the most frequently traveled road segments for siting refueling stations. The second stage focuses on adding additional refueling stations to serve vehicles whose demands are not directly satisfied by the refueling stations identified in the first stage. The last stage further adjusts and optimizes the refueling station plan generated by the first two stages. A genetic simulated annealing algorithm is proposed to solve the optimization problem in the second stage and the results are compared to those from the genetic algorithm. A case study is also conducted to demonstrate the effectiveness of the proposed method and algorithm. The results indicate the proposed method can provide practical and effective solutions that help planners and government agencies make informed refueling station location decisions.

  7. Autonomous Airborne Refueling Demonstration: Phase I Flight-Test Results

    Science.gov (United States)

    Dibley, Ryan P.; Allen, Michael J.; Nabaa, Nassib

    2007-01-01

    The first phase of the Autonomous Airborne Refueling Demonstration (AARD) project was completed on August 30, 2006. The goal of this 15-month effort was to develop and flight-test a system to demonstrate an autonomous refueling engagement using the Navy style hose-and-drogue air-to-air refueling method. The prime contractor for this Defense Advanced Research Projects Agency (DARPA) sponsored program was Sierra Nevada Corporation (SNC), Sparks, Nevada. The responsible flight-test organization was the National Aeronautics and Space Administration (NASA) Dryden Flight Research Center (DFRC), Edwards, California, which also provided the F/A-18 receiver airplane (McDonnell Douglas, now The Boeing Company, Chicago, Illinois). The B-707-300 tanker airplane (The Boeing Company) was contracted through Omega Aerial Refueling Services, Inc., Alexandria, Virginia, and the optical tracking system was contracted through OCTEC Ltd., Bracknell, Berkshire, United Kingdom. Nine research flights were flown, testing the functionality and performance of the system in a stepwise manner, culminating in the plug attempts on the final flight. Relative position keeping was found to be very stable and accurate. The receiver aircraft was capable of following the tanker aircraft through turns while maintaining its relative position. During the last flight, six capture attempts were made, two of which were successful. The four misses demonstrated excellent characteristics, the receiver retreating from the drogue in a controlled, safe, and predictable manner that precluded contact between the drogue and the receiver aircraft. The position of the receiver aircraft when engaged and in position for refueling was found to be 5.5 to 8.5 ft low of the ideal position. The controller inputs to the F/A-18 were found to be extremely small.

  8. Autonomous Airborne Refueling Demonstration, Phase I Flight-Test Results

    Science.gov (United States)

    Dibley, Ryan P.; Allen, Michael J.; Nabaa, Nassib

    2007-01-01

    The first phase of the Autonomous Airborne Refueling Demonstration (AARD) project was completed on August 30, 2006. The goal of this 15-month effort was to develop and flight-test a system to demonstrate an autonomous refueling engagement using the Navy style hose-and-drogue air-to-air refueling method. The prime contractor for this Defense Advanced Research Projects Agency (DARPA) sponsored program was Sierra Nevada Corporation (SNC), Sparks, Nevada. The responsible flight-test organization was the NASA Dryden Flight Research Center (DFRC), Edwards, California, which also provided the F/A-18 receiver airplane (McDonnell Douglas, now The Boeing Company, Chicago, Illinois). The B-707-300 tanker airplane (The Boeing Company) was contracted through Omega Aerial Refueling Services, Inc., Alexandria, Virginia, and the optical tracking system was contracted through OCTEC Ltd., Bracknell, Berkshire, United Kingdom. Nine research flights were flown, testing the functionality and performance of the system in a stepwise manner, culminating in the plug attempts on the final flight. Relative position keeping was found to be very stable and accurate. The receiver aircraft was capable of following the tanker aircraft through turns while maintaining its relative position. During the last flight, six capture attempts were made, two of which were successful. The four misses demonstrated excellent characteristics, the receiver retreating from the drogue in a controlled, safe, and predictable manner that precluded contact between the drogue and the receiver aircraft. The position of the receiver aircraft when engaged and in position for refueling was found to be 5.5 to 8.5 ft low of the ideal position. The controller inputs to the F/A-18 were found to be extremely small

  9. TOPOLOGY AND CASCADING LINE OUTAGES IN POWER GRIDS

    Institute of Scientific and Technical Information of China (English)

    David L. PEPYNE

    2007-01-01

    Motivated by the small world network research of Watts & Strogatz, this paper studies relationships between topology and cascading line outages in electric power grids. Cascading line outages are a type of cascading collapse that can occur in power grids when the transmission network is congested. It is characterized by a self-sustaining sequence of line outages followed by grid breakup, which generally leads to widespread blackout. The main findings of this work are twofold: On one hand, the work suggests that topologies with more disorder in their interconnection topology tend to be robust with respect to cascading line outages in the sense of being able to support greater generation and demand levels than more regularly interconnected topologies. On the other hand, the work suggests that topologies with more disorder tend to be more fragile in that should a cascade get started, they tend to break apart after fewer outages than more regularly interconnected topologies. Thus, as has been observed in other complex networks, there appears to be a tradeoff between robustness and fragility.These results were established using synthetically generated power grid topologies and verified using the IEEE 57 bus and 188 bus power grid test cases.

  10. Outage Performance in Cognitive Radio Systems with Opportunistic Interference Cancelation

    DEFF Research Database (Denmark)

    Di Taranto, Rocco; Popovski, Petar

    2011-01-01

    transmitter. First, we investigate how the secondary transmitter, when using OIC and S-OIC for fixed transmitting power, should select its rate in order to meet its target outage probability under different assumptions about the channel-state-information available at the secondary transmitter. We study three...... different cases and for each of them identify the region of achievable primary and secondary rates. Second, we determine how the secondary transmitter should select its transmitting power not to violate the target outage probability at the primary terminals. Our numerical results show that the best......) and the interplay between the allowed power at the secondary transmitter (which depends on the target outage probability at the primary receiver) and the decodability at the secondary receiver....

  11. Multicast Capacity Scaling of Wireless Networks with Multicast Outage

    CERN Document Server

    Liu, Chun-Hung

    2010-01-01

    Multicast transmission has several distinctive traits as opposed to more commonly studied unicast networks. Specially, these include (i) identical packets must be delivered successfully to several nodes, (ii) outage could simultaneously happen at different receivers, and (iii) the multicast rate is dominated by the receiver with the weakest link in order to minimize outage and retransmission. To capture these key traits, we utilize a Poisson cluster process consisting of a distinct Poisson point process (PPP) for the transmitters and receivers, and then define the multicast transmission capacity (MTC) as the maximum achievable multicast rate times the number of multicast clusters per unit volume, accounting for outages and retransmissions. Our main result shows that if $\\tau$ transmission attempts are allowed in a multicast cluster, the MTC is $\\Theta\\left(\\rho k^{x}\\log(k)\\right)$ where $\\rho$ and $x$ are functions of $\\tau$ depending on the network size and density, and $k$ is the average number of the inte...

  12. Assessment of Refueling Hose Visibility: Post-Cleaning Evaluation

    Science.gov (United States)

    2013-10-01

    visibility, contrast, illumination, viewing geometries, spectral band, NVG , SWIR, LWIR, standards 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...drogue which incorporates a white canopy over 52” in diameter with a 1 foot wide white cloth used for rotary wing helicopters aerial refueling. Night...Light-Emitting Diode LWIR – Long-Wave Infra-Red Navair – U.S. Navy Naval Air Systems Command NVG – Night Vision Goggles SWIR – Short-Wave Infra-Red

  13. Obtaining statistics of cascading line outages spreading in an electric transmission network from standard utility data

    CERN Document Server

    Dobson, Ian

    2015-01-01

    We show how to use standard transmission line outage historical data to obtain the network topology in such a way that cascades of line outages can be easily located on the network. Then we obtain statistics quantifying how cascading outages typically spread on the network. Processing real outage data is fundamental for understanding cascading and for evaluating the validity of the many different models and simulations that have been proposed for cascading in power networks.

  14. Threshold-based monitoring of cascading outages with PMU measurements of area angle

    OpenAIRE

    Darvishi, Atena; Dobson, Ian

    2014-01-01

    When power grids are heavily stressed with a bulk power transfer, it is useful to have a fast indication of the increased stress when multiple line outages occur. Reducing the bulk power transfer when the outages are severe could forestall further cascading of the outages. We show that synchrophasor measurements of voltage angles at all the area tie lines can be used to indicate the severity of multiple outages. These synchrophasor measurements are readily combined into an "area angle" that c...

  15. Outage probability analysis for superposition coded symmetric relaying

    Institute of Scientific and Technical Information of China (English)

    WU Yi; ZHENG Meng; FEI ZeSong; LARSSON Erik G.; KUANG JingMing

    2013-01-01

    Superposition coded symmetric relaying is a bandwidth-efficient cooperative scheme where each source node simultaneously transmits both its own "local" packet and "relay" packet that originated at its partner by adding the modulated local and relay signals in Euclidean space. This paper investigates the power allocation and outage probability of a superposition coded symmetric relaying system with finite-constellation signaling. We first derive the mutual information (MI) metrics for the system. The derived MI metrics consist of two parts: one represents the MI conveyed by the modulated signal corresponding to its own data, and the other represents the MI conveyed by the modulated signal corresponding to its partner's data. Using MI based effective signal-to-noise ratio mapping technique, we attain expressions for the outage probability. Furthermore, we discuss power allocation policies that minimize the outage probability. Simulation results are presented to verify the correctness of the outage probability analysis and the benefits of the power allocation.

  16. Efficient Simulation of the Outage Probability of Multihop Systems

    KAUST Repository

    Ben Issaid, Chaouki

    2017-08-01

    In this paper, we present an efficient importance sampling estimator for the evaluation of the outage probability of multihop systems with amplify-and-forward channel state-information-assisted. The proposed estimator is endowed with the bounded relative error property. Simulation results show a significant reduction in terms of number of simulation runs compared to naive Monte Carlo.

  17. Does Your Domestic Photovoltaic Energy System Survive Grid Outages?

    Directory of Open Access Journals (Sweden)

    Marijn R. Jongerden

    2016-09-01

    Full Text Available Domestic renewable energy systems, including photovoltaic energy generation, as well as local storage, are becoming increasingly popular and economically feasible, but do come with a wide range of options. Hence, it can be difficult to match their specification to specific customer’s needs. Next to the usage-specific demand profiles and location-specific production profiles, local energy storage through the use of batteries is becoming increasingly important, since it allows one to balance variations in production and demand, either locally or via the grid. Moreover, local storage can also help to ensure a continuous energy supply in the presence of grid outages, at least for a while. Hybrid Petri net (HPN models allow one to analyze the effect of different battery management strategies on the continuity of such energy systems in the case of grid outages. The current paper focuses on one of these strategies, the so-called smart strategy, that reserves a certain percentage of the battery capacity to be only used in case of grid outages. Additionally, we introduce a new strategy that makes better use of the reserved backup capacity, by reducing the demand in the presence of a grid outage through a prioritization mechanism. This new strategy, called power-save, only allows the essential (high-priority demand to draw from the battery during power outages. We show that this new strategy outperforms previously-proposed strategies through a careful analysis of a number of scenarios and for a selection of survivability measures, such as minimum survivability per day, number of survivable hours per day, minimum survivability per year and various survivability quantiles.

  18. Using Predictive Analytics to Predict Power Outages from Severe Weather

    Science.gov (United States)

    Wanik, D. W.; Anagnostou, E. N.; Hartman, B.; Frediani, M. E.; Astitha, M.

    2015-12-01

    The distribution of reliable power is essential to businesses, public services, and our daily lives. With the growing abundance of data being collected and created by industry (i.e. outage data), government agencies (i.e. land cover), and academia (i.e. weather forecasts), we can begin to tackle problems that previously seemed too complex to solve. In this session, we will present newly developed tools to aid decision-support challenges at electric distribution utilities that must mitigate, prepare for, respond to and recover from severe weather. We will show a performance evaluation of outage predictive models built for Eversource Energy (formerly Connecticut Light & Power) for storms of all types (i.e. blizzards, thunderstorms and hurricanes) and magnitudes (from 20 to >15,000 outages). High resolution weather simulations (simulated with the Weather and Research Forecast Model) were joined with utility outage data to calibrate four types of models: a decision tree (DT), random forest (RF), boosted gradient tree (BT) and an ensemble (ENS) decision tree regression that combined predictions from DT, RF and BT. The study shows that the ENS model forced with weather, infrastructure and land cover data was superior to the other models we evaluated, especially in terms of predicting the spatial distribution of outages. This research has the potential to be used for other critical infrastructure systems (such as telecommunications, drinking water and gas distribution networks), and can be readily expanded to the entire New England region to facilitate better planning and coordination among decision-makers when severe weather strikes.

  19. A framework and review of customer outage costs: Integration and analysis of electric utility outage cost surveys

    Energy Technology Data Exchange (ETDEWEB)

    Lawton, Leora; Sullivan, Michael; Van Liere, Kent; Katz, Aaron; Eto, Joseph

    2003-11-01

    A clear understanding of the monetary value that customers place on reliability and the factors that give rise to higher and lower values is an essential tool in determining investment in the grid. The recent National Transmission Grid Study recognizes the need for this information as one of growing importance for both public and private decision makers. In response, the U.S. Department of Energy has undertaken this study, as a first step toward addressing the current absence of consistent data needed to support better estimates of the economic value of electricity reliability. Twenty-four studies, conducted by eight electric utilities between 1989 and 2002 representing residential and commercial/industrial (small, medium and large) customer groups, were chosen for analysis. The studies cover virtually all of the Southeast, most of the western United States, including California, rural Washington and Oregon, and the Midwest south and east of Chicago. All variables were standardized to a consistent metric and dollar amounts were adjusted to the 2002 CPI. The data were then incorporated into a meta-database in which each outage scenario (e.g., the lost of electric service for one hour on a weekday summer afternoon) is treated as an independent case or record both to permit comparisons between outage characteristics and to increase the statistical power of analysis results. Unadjusted average outage costs and Tobit models that estimate customer damage functions are presented. The customer damage functions express customer outage costs for a given outage scenario and customer class as a function of location, time of day, consumption, and business type. One can use the damage functions to calculate outage costs for specific customer types. For example, using the customer damage functions, the cost experienced by an ''average'' customer resulting from a 1 hour summer afternoon outage is estimated to be approximately $3 for a residential customer, $1

  20. Hurricane Isaac: A Longitudinal Analysis of Storm Characteristics and Power Outage Risk.

    Science.gov (United States)

    Tonn, Gina L; Guikema, Seth D; Ferreira, Celso M; Quiring, Steven M

    2016-10-01

    In August 2012, Hurricane Isaac, a Category 1 hurricane at landfall, caused extensive power outages in Louisiana. The storm brought high winds, storm surge, and flooding to Louisiana, and power outages were widespread and prolonged. Hourly power outage data for the state of Louisiana were collected during the storm and analyzed. This analysis included correlation of hourly power outage figures by zip code with storm conditions including wind, rainfall, and storm surge using a nonparametric ensemble data mining approach. Results were analyzed to understand how correlation of power outages with storm conditions differed geographically within the state. This analysis provided insight on how rainfall and storm surge, along with wind, contribute to power outages in hurricanes. By conducting a longitudinal study of outages at the zip code level, we were able to gain insight into the causal drivers of power outages during hurricanes. Our analysis showed that the statistical importance of storm characteristic covariates to power outages varies geographically. For Hurricane Isaac, wind speed, precipitation, and previous outages generally had high importance, whereas storm surge had lower importance, even in zip codes that experienced significant surge. The results of this analysis can inform the development of power outage forecasting models, which often focus strictly on wind-related covariates. Our study of Hurricane Isaac indicates that inclusion of other covariates, particularly precipitation, may improve model accuracy and robustness across a range of storm conditions and geography.

  1. Insights from Hydrogen Refueling Station Manufacturing Competitiveness Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mayyas, Ahmad

    2015-12-18

    In work for the Clean Energy Manufacturing Analysis Center (CEMAC), NREL is currently collaborating with Great Lakes Wind Network in conducting a comprehensive hydrogen refueling stations manufacturing competitiveness and supply chain analyses. In this project, CEMAC will be looking at several metrics that will facilitate understanding of the interactions between and within the HRS supply chain, such metrics include innovation potential, intellectual properties, learning curves, related industries and clustering, existing supply chains, ease of doing business, and regulations and safety. This presentation to Fuel Cell Seminar and Energy Exposition 2015 highlights initial findings from CEMAC's analysis.

  2. Next Generation Tanker: Optimizing Air Refueling Capabilities in 2030 with a Divested KC-10 Fleet

    Science.gov (United States)

    2015-06-19

    NEXT GENERATION TANKER: OPTIMIZING AIR REFUELING CAPABILITIES IN 2030 WITH A DIVESTED KC-10 FLEET...OPTIMIZING AIR REFUELING CAPABILITIES IN 2030 WITH A DIVESTED KC-10 FLEET GRADUATE RESEARCH PAPER Presented to the Faculty Department...CAPABILITIES IN 2030 WITH A DIVESTED KC-10 FLEET Christopher R. MacDonald, BS, MBA Major, USAF Committee Membership: Dr. Darryl

  3. Forward Arming and Refueling Points for Fighter Aircraft: Power Projection in an Antiaccess Environment

    Science.gov (United States)

    2014-10-01

    TITLE AND SUBTITLE Forward Arming and Refueling Points for Fighter Aircraft: Power Projection in an Antiaccess Environment 5a. CONTRACT NUMBER 5b...Arming and Refueling Point (FARP) Using Discrete Event Simulation,” Graduate Research Project AFIT/ MLM / ENS/05-08 (Wright-Patterson AFB, OH: Air

  4. The Feasibility of Pellet Re-Fuelling of a Fusion Reactor

    DEFF Research Database (Denmark)

    Chang, Tinghong; Jørgensen, L. W.; Nielsen, P.

    1980-01-01

    The feasibility of re-fuelling a fusion reactor by injecting pellets of frozen hydrogen isotopes is reviewed. First a general look is taken of the dominant energy fluxes received by the pellet, the re-fuelling rate required and the relation between pellet size, injection speed and frequency...

  5. Outage Constrained Secrecy Rate Maximization Using Cooperative Jamming

    CERN Document Server

    Luo, Shuangyu; Petropulu, Athina

    2012-01-01

    We consider a Gaussian MISO wiretap channel, where a multi-antenna source communicates with a single-antenna destination in the presence of a single-antenna eavesdropper. The communication is assisted by multi-antenna helpers that act as jammers to the eavesdropper. Each helper independently transmits noise which lies in the null space of the channel to the destination, thus creates no interference to the destination. Under the assumption that there is eavesdropper channel uncertainty, we derive the optimal covariance matrix for the source signal so that the secrecy rate is maximized subject to probability of outage and power constraints. Assuming that the eavesdropper channels follow zero-mean Gaussian model with known covariances, we derive the outage probability in a closed form. Simulation results in support of the analysis are provided.

  6. Outage analysis of opportunistic decode-and-forward relaying

    KAUST Repository

    Tourki, Kamel

    2010-09-01

    In this paper, we investigate a dual-hop opportunistic decode-and-forward relaying scheme where the source may or not be able to communicate directly with the destination. We first derive statistics based on exact probability density function (PDF) of each hop. Then, the PDFs are used to determine closed-form outage probability expression for a transmission rate R. Furthermore, we evaluate the asymptotic outage performance and the diversity order is deduced. Unlike existing works where the analysis focused on high signal-to-noise ratio (SNR) regime, such results are important to enable the designers to take decisions regarding practical systems that operate at low SNR regime. We show that performance simulation results coincide with our analytical results under practical assumption of unbalanced hops. © 2010 IEEE.

  7. Outage Probability for Multi-Cell Processing under Rayleigh Fading

    CERN Document Server

    Garcia, Virgile; Lebedev, Nikolai

    2010-01-01

    Multi-cell processing, also called Coordinated Multiple Point (CoMP), is a very promising distributed multi-antennas technique that uses neighbour cell's antennas. This is expected to be part of next generation cellular networks standards such as LTE-A. Small cell networks in dense urban environment are mainly limited by interferences and CoMP can strongly take advantage of this fact to improve cell-edge users' throughput. This paper provides an analytical derivation of the capacity outage probability for CoMP experiencing fast Rayleigh fading. Only the average received power (slow varying fading) has to be known, and perfect Channel State Information (CSI) is not required. An optimisation of the successfully received data-rate is then derived with respect to the number of cooperating stations and the outage probability, illustrated by numerical examples.

  8. Outage probability of distributed beamforming with co-channel interference

    KAUST Repository

    Yang, Liang

    2012-03-01

    In this letter, we consider a distributed beamforming scheme (DBF) in the presence of equal-power co-channel interferers for both amplify-and-forward and decode-and-forward relaying protocols over Rayleigh fading channels. We first derive outage probability expressions for the DBF systems. We then present a performance analysis for a scheme relying on source selection. Numerical results are finally presented to verify our analysis. © 2011 IEEE.

  9. Outage Probability Analysis of FSO Links over Foggy Channel

    KAUST Repository

    Esmail, Maged Abdullah

    2017-02-22

    Outdoor Free space optic (FSO) communication systems are sensitive to atmospheric impairments such as turbulence and fog, in addition to being subject to pointing errors. Fog is particularly severe because it induces an attenuation that may vary from few dBs up to few hundreds of dBs per kilometer. Pointing errors also distort the link alignment and cause signal fading. In this paper, we investigate and analyze the FSO systems performance under fog conditions and pointing errors in terms of outage probability. We then study the impact of several effective communication mitigation techniques that can improve the system performance including multi-hop, transmit laser selection (TLS) and hybrid RF/FSO transmission. Closed-form expressions for the outage probability are derived and practical and comprehensive numerical examples are suggested to assess the obtained results. We found that the FSO system has limited performance that prevents applying FSO in wireless microcells that have a 500 m minimum cell radius. The performance degrades more when pointing errors appear. Increasing the transmitted power can improve the performance under light to moderate fog. However, under thick and dense fog the improvement is negligible. Using mitigation techniques can play a major role in improving the range and outage probability.

  10. Distortion outage minimization in Nakagami fading using limited feedback

    Science.gov (United States)

    Wang, Chih-Hong; Dey, Subhrakanti

    2011-12-01

    We focus on a decentralized estimation problem via a clustered wireless sensor network measuring a random Gaussian source where the clusterheads amplify and forward their received signals (from the intra-cluster sensors) over orthogonal independent stationary Nakagami fading channels to a remote fusion center that reconstructs an estimate of the original source. The objective of this paper is to design clusterhead transmit power allocation policies to minimize the distortion outage probability at the fusion center, subject to an expected sum transmit power constraint. In the case when full channel state information (CSI) is available at the clusterhead transmitters, the optimization problem can be shown to be convex and is solved exactly. When only rate-limited channel feedback is available, we design a number of computationally efficient sub-optimal power allocation algorithms to solve the associated non-convex optimization problem. We also derive an approximation for the diversity order of the distortion outage probability in the limit when the average transmission power goes to infinity. Numerical results illustrate that the sub-optimal power allocation algorithms perform very well and can close the outage probability gap between the constant power allocation (no CSI) and full CSI-based optimal power allocation with only 3-4 bits of channel feedback.

  11. Controlled Tripping of Overheated Lines Mitigates Power Outages

    CERN Document Server

    Pfitzner, René; Chertkov, Michael

    2011-01-01

    We study cascades of blackouts in the model of the Polish (transmission) power grid (2700 nodes and 3504 transmission lines). A cascade is initiated by a sufficiently severe initial contingency tripping. The cascade advances via sequential tripping of many more overheated lines (with the thermal limits exceeded), islanding loads and generators and eventually arriving at a fixed point with the surviving part of the system being power- flow-balanced and the rest of the system being outaged. Utilizing the quasi-static model for cascade propagation, introduced in our earlier study (Statistical Classification of Cascading Failures in Power Grids, IEEE PES GM 2011), we analyze how the severity of the cascade depends on the order of tripping overheated lines. Our main observation is that the order of tripping has a tremendous effect on the size of the resulting outage: the probability distribution function of the outage size is broad; moreover in many of the cases studied, picking an overheated line at random result...

  12. Distortion outage minimization in Nakagami fading using limited feedback

    Directory of Open Access Journals (Sweden)

    Wang Chih-Hong

    2011-01-01

    Full Text Available Abstract We focus on a decentralized estimation problem via a clustered wireless sensor network measuring a random Gaussian source where the clusterheads amplify and forward their received signals (from the intra-cluster sensors over orthogonal independent stationary Nakagami fading channels to a remote fusion center that reconstructs an estimate of the original source. The objective of this paper is to design clusterhead transmit power allocation policies to minimize the distortion outage probability at the fusion center, subject to an expected sum transmit power constraint. In the case when full channel state information (CSI is available at the clusterhead transmitters, the optimization problem can be shown to be convex and is solved exactly. When only rate-limited channel feedback is available, we design a number of computationally efficient sub-optimal power allocation algorithms to solve the associated non-convex optimization problem. We also derive an approximation for the diversity order of the distortion outage probability in the limit when the average transmission power goes to infinity. Numerical results illustrate that the sub-optimal power allocation algorithms perform very well and can close the outage probability gap between the constant power allocation (no CSI and full CSI-based optimal power allocation with only 3-4 bits of channel feedback.

  13. Autonomous Aerial Refueling Ground Test Demonstration--A Sensor-in-the-Loop, Non-Tracking Method.

    Science.gov (United States)

    Chen, Chao-I; Koseluk, Robert; Buchanan, Chase; Duerner, Andrew; Jeppesen, Brian; Laux, Hunter

    2015-05-11

    An essential capability for an unmanned aerial vehicle (UAV) to extend its airborne duration without increasing the size of the aircraft is called the autonomous aerial refueling (AAR). This paper proposes a sensor-in-the-loop, non-tracking method for probe-and-drogue style autonomous aerial refueling tasks by combining sensitivity adjustments of a 3D Flash LIDAR camera with computer vision based image-processing techniques. The method overcomes the inherit ambiguity issues when reconstructing 3D information from traditional 2D images by taking advantage of ready to use 3D point cloud data from the camera, followed by well-established computer vision techniques. These techniques include curve fitting algorithms and outlier removal with the random sample consensus (RANSAC) algorithm to reliably estimate the drogue center in 3D space, as well as to establish the relative position between the probe and the drogue. To demonstrate the feasibility of the proposed method on a real system, a ground navigation robot was designed and fabricated. Results presented in the paper show that using images acquired from a 3D Flash LIDAR camera as real time visual feedback, the ground robot is able to track a moving simulated drogue and continuously narrow the gap between the robot and the target autonomously.

  14. Autonomous Aerial Refueling Ground Test Demonstration—A Sensor-in-the-Loop, Non-Tracking Method

    Directory of Open Access Journals (Sweden)

    Chao-I Chen

    2015-05-01

    Full Text Available An essential capability for an unmanned aerial vehicle (UAV to extend its airborne duration without increasing the size of the aircraft is called the autonomous aerial refueling (AAR. This paper proposes a sensor-in-the-loop, non-tracking method for probe-and-drogue style autonomous aerial refueling tasks by combining sensitivity adjustments of a 3D Flash LIDAR camera with computer vision based image-processing techniques. The method overcomes the inherit ambiguity issues when reconstructing 3D information from traditional 2D images by taking advantage of ready to use 3D point cloud data from the camera, followed by well-established computer vision techniques. These techniques include curve fitting algorithms and outlier removal with the random sample consensus (RANSAC algorithm to reliably estimate the drogue center in 3D space, as well as to establish the relative position between the probe and the drogue. To demonstrate the feasibility of the proposed method on a real system, a ground navigation robot was designed and fabricated. Results presented in the paper show that using images acquired from a 3D Flash LIDAR camera as real time visual feedback, the ground robot is able to track a moving simulated drogue and continuously narrow the gap between the robot and the target autonomously.

  15. Mechanically refuelable zinc/air electric vehicle cells

    Science.gov (United States)

    Noring, J.; Gordon, S.; Maimoni, A.; Spragge, M.; Cooper, J. F.

    1992-12-01

    Refuelable zinc/air batteries have long been considered for motive as well as stationary power because of a combination of high specific energy, low initial cost, and the possibility of mechanical recharge by electrolyte exchange and additions of metallic zinc. In this context, advanced slurry batteries, stationary packed bed cells, and batteries offering replaceable cassettes have been reported recently. The authors are developing self-feeding, particulate-zinc/air batteries for electric vehicle applications. Emissionless vehicle legislation in California motivated efforts to consider a new approach to providing an electric vehicle with long range (400 km), rapid refueling (10 minutes) and highway safe acceleration - factors which define the essential functions of common automobiles. Such an electric vehicle would not compete with emerging secondary battery vehicles in specialized applications (commuting vehicles, delivery trucks). Rather, different markets would be sought where long range or rapid range extension are important. Examples are: taxis, continuous-duty fork-lift trucks and shuttle busses, and general purpose automobiles having modest acceleration capabilities. In the long range, a mature fleet would best use regional plants to efficiently recover zinc from battery reaction products. One option would be to use chemical/thermal reduction to recover the zinc. The work described focuses on development of battery configurations which efficiently and completely consume zinc particles, without clogging or changing discharge characteristics.

  16. Fire Protection Engineering Design Brief Template. Hydrogen Refueling Station.

    Energy Technology Data Exchange (ETDEWEB)

    LaFleur, Angela Christine [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Muna, Alice Baca [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Groth, Katrina M. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-08-01

    Building a hydrogen infrastructure system is critical to supporting the development of alternate- fuel vehicles. This report provides a methodology for implementing a performance-based design of an outdoor hydrogen refueling station that does not meet specific prescriptive requirements in NFPA 2, The Hydrogen Technologies Code . Performance-based designs are a code-compliant alternative to meeting prescriptive requirements. Compliance is demonstrated by comparing a prescriptive-based fueling station design with a performance-based design approach using Quantitative Risk Assessment (QRA) methods and hydrogen risk assessment tools. This template utilizes the Sandia-developed QRA tool, Hydrogen Risk Analysis Models (HyRAM), which combines reduced-order deterministic models that characterize hydrogen release and flame behavior with probabilistic risk models to quantify risk values. Each project is unique and this template is not intended to account for site-specific characteristics. Instead, example content and a methodology are provided for a representative hydrogen refueling site which can be built upon for new hydrogen applications.

  17. Cascading Power Outages Propagate Locally in an Influence Graph that is not the Actual Grid Topology

    CERN Document Server

    Hines, Paul D H; Rezaei, Pooya

    2015-01-01

    In a cascading power transmission outage, component outages propagate non-locally; after one component outages, the next failure may be very distant, both topologically and geographically. As a result, simple models of topological contagion do not accurately represent the propagation of cascades in power systems. However, cascading power outages do follow patterns, some of which are useful in understanding and reducing blackout risk. This paper describes a method by which the data from many cascading failure simulations can be transformed into a graph-based model of influences that provides actionable information about the many ways that cascades propagate in a particular system. The resulting "influence graph" model is Markovian, since component outage probabilities depend only on the outages that occurred in the prior generation. To validate the model we compare the distribution of cascade sizes resulting from n-2 contingencies in a 2896 branch test case to cascade sizes in the influence graph. The two dist...

  18. Hybrid Model for Cascading Outage in a Power System: A Numerical Study

    Science.gov (United States)

    Susuki, Yoshihiko; Takatsuji, Yu; Hikihara, Takashi

    Analysis of cascading outages in power systems is important for understanding why large blackouts emerge and how to prevent them. Cascading outages are complex dynamics of power systems, and one cause of them is the interaction between swing dynamics of synchronous machines and protection operation of relays and circuit breakers. This paper uses hybrid dynamical systems as a mathematical model for cascading outages caused by the interaction. Hybrid dynamical systems can combine families of flows describing swing dynamics with switching rules that are based on protection operation. This paper refers to data on a cascading outage in the September 2003 blackout in Italy and shows a hybrid dynamical system by which propagation of outages reproduced is consistent with the data. This result suggests that hybrid dynamical systems can provide an effective model for the analysis of cascading outages in power systems.

  19. Outage Probability of General Ad Hoc Networks in the High-Reliability Regime

    CERN Document Server

    Giacomelli, Riccardo; Haenggi, Martin

    2010-01-01

    Outage probabilities in wireless networks depend on various factors: the node distribution, the MAC scheme, and the models for path loss, fading and transmission success. In prior work on outage characterization for networks with randomly placed nodes, most of the emphasis was put on networks whose nodes are Poisson distributed and where ALOHA is used as the MAC protocol. In this paper we provide a general framework for the analysis of outage probabilities in the high-reliability regime. The outage probability characterization is based on two parameters: the intrinsic spatial contention $\\gamma$ of the network, introduced in [1], and the coordination level achieved by the MAC as measured by the interference scaling exponent $\\kappa$ introduced in this paper. We study outage probabilities under the signal-to-interference ratio (SIR) model, Rayleigh fading, and power-law path loss, and explain how the two parameters depend on the network model. The main result is that the outage probability approaches $\\gamma\\e...

  20. Analysis of Fixed Outage Transmission Schemes: A Finer Look at the Full Multiplexing Point

    CERN Document Server

    Wu, Peng

    2007-01-01

    This paper studies the performance of transmission schemes that have rate that increases with average SNR while maintaining a fixed outage probability. This is in contrast to the classical Zheng-Tse diversity-multiplexing tradeoff (DMT) that focuses on increasing rate and decreasing outage probability. Three different systems are explored: antenna diversity systems, time/frequency diversity systems, and automatic repeat request (ARQ) systems. In order to accurately study performance in the fixed outage setting, it is necesary to go beyond the coarse, asymptotic multiplexing gain metric. In the case of antenna diversity and time/frequency diversity, an affine approximation to high SNR outage capacity (i.e., multiplexing gain plus a power/rate offset) accurately describes performance and shows the very significant benefits of diversity. ARQ is also seen to provide a significant performance advantage, but even an affine approximation to outage capacity is unable to capture this advantage and outage capacity must...

  1. On Outage Performance of Spectrum-Sharing Communication over M-Block Fading

    KAUST Repository

    Alabbasi, AbdulRahman

    2015-12-06

    In this paper, we consider a cognitive radio system in which a block-fading channel is assumed. Each transmission frame consists of M blocks and each block undergoes a different channel gain. Instantaneous channel state information about the interference links remains unknown to the primary and secondary users. We minimize the secondary user\\'s targeted outage probability over the block-fading channels. To protect the primary user, a statistical constraint on its targeted outage probability is enforced. The secondary user\\'s targeted outage region and the corresponding optimal power are derived. We also propose two sub-optimal power strategies and derive compact expressions for the corresponding outage probabilities. These probabilities are shown to be asymptotic lower and upper bounds on the outage probability. Utilizing these bounds, we derive the exact diversity order of the secondary user outage probability. Selected numerical results are presented to characterize the system\\'s behavior.

  2. The Opportunity Cost of Electricity Outages and Privatization of Substations in Nepal

    OpenAIRE

    Roop Jyoti; Aygul Ozbafli; Glenn Jenkins

    2006-01-01

    The unreliability of electricity supplies is a major cause of the high cost of manufacturing in developing countries. In this paper, we are able to measure the cost imposed by power outages and suggest some feasible mitigating measures. The study employs a rich, if not unique, set of data from three large manufacturing enterprises in Nepal. Using it, the opportunity costs to the enterprises from lost production from electricity outages can be estimated accurately. Power outages due to substat...

  3. Separating the Effect of Independent Interference Sources with Rayleigh Faded Signal Link: Outage Analysis and Applications

    CERN Document Server

    Kahlon, Arshdeep S; Periyalwar, Shalini; Yanikomeroglu, Halim

    2012-01-01

    We show that, for independent interfering sources and a signal link with exponentially distributed received power, the total probability of outage can be decomposed as a simple expression of the outages from the individual interfering sources. We give a mathematical proof of this result, and discuss some immediate implications, showing how it results in important simplifications to statistical outage analysis. We also discuss its application to two active topics of study: spectrum sharing, and sum of interference powers (e.g., lognormal) analysis.

  4. Hybrid Model for Cascading Outage in a Power System: A Numerical Study

    OpenAIRE

    Susuki, Yoshihiko; Takatsuji, Yu; Hikihara, Takashi

    2009-01-01

    Analysis of cascading outages in power systems is important for understanding why large blackouts emerge and how to prevent them. Cascading outages are complex dynamics of power systems, and one cause of them is the interaction between swing dynamics of synchronous machines and protection operation of relays and circuit breakers. This paper uses hybrid dynamical systems as a mathematical model for cascading outages caused by the interaction. Hybrid dynamical systems can combine families of fl...

  5. Secrecy Cognitive Gain of Cognitive Radio Sensor Networks with Primary Outage Constraint

    National Research Council Canada - National Science Library

    Ma, Hongyu; Niu, Kai; Wu, Weiling; Li, Shengyu; Chu, Guangqian

    2015-01-01

    ...) with primary outage constraint, for which a tractable framework is developed to analyze the secrecy performance for CRSNs related to the random channel characteristics, the spatial distributions...

  6. Analysis of the effects of communication and surveillance facility service outages on traffic separations.

    Science.gov (United States)

    Borener, Sherry S; Guzhva, Vitaly S

    2014-09-01

    This study examines air traffic separations in the service volumes of communication and surveillance facilities that experienced service outages. The data sample consists of 338 unscheduled service outages that happened in 2010 and 2011 at facilities located in the vicinity of 15 major traffic hubs. For each outage, radar track data were collected and used to calculate traffic separations during the period of 30 minutes before to 30 minutes after an outage. Then, the separation index, which indicates the percentage of horizontal separation retained between two aircraft at the same altitude, was estimated. The separation index and loss of separation events were analyzed using lognormal and negative binomial regression models. The results suggest that the count of separation events peaks during the 15 minutes after an outage. In addition, traffic collision avoidance system resolution advisory (TCAS RA) encounters and Category A separation events are 1.31 times more likely during the 30 minutes following the beginning of a service outage, as compared to the 30 minutes before the outage, for both types of facilities. Also, the separation index values are 19% lower following a surveillance facility outage and 4% lower following a communication facility service loss. This study provides evidence that unscheduled service outages of air traffic management facilities are associated with lost or reduced traffic separations and thus can be considered precursors to hazardous loss of separation events.

  7. Design Concepts for an Outage Control Center Information Dashboard

    Energy Technology Data Exchange (ETDEWEB)

    Hugo, Jacques Victor [Idaho National Lab. (INL), Idaho Falls, ID (United States); St Germain, Shawn Walter [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thompson, Cheradan Jo [Idaho National Lab. (INL), Idaho Falls, ID (United States); Whitesides, McKenzie Jo [Idaho National Lab. (INL), Idaho Falls, ID (United States); Farris, Ronald Keith [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-12-01

    The nuclear industry, and the business world in general, is facing a rapidly increasing amount of data to be dealt with on a daily basis. In the last two decades, the steady improvement of data storage devices and means to create and collect data along the way influenced the manner in which we deal with information. Most data is still stored without filtering and refinement for later use. Many functions at a nuclear power plant generate vast amounts of data, with scheduled and unscheduled outages being a prime example of a source of some of the most complex data sets at the plant. To make matters worse, modern information and communications technology is making it possible to collect and store data faster than our ability to use it for making decisions. However, in most applications, especially outages, raw data has no value in itself; instead, managers, engineers and other specialists want to extract the information contained in it. The complexity and sheer volume of data could lead to information overload, resulting in getting lost in data that may be irrelevant to the task at hand, processed in an inappropriate way, or presented in an ineffective way. To prevent information overload, many data sources are ignored so production opportunities are lost because utilities lack the ability to deal with the enormous data volumes properly. Decision-makers are often confronted with large amounts of disparate, conflicting and dynamic information, which are available from multiple heterogeneous sources. Information and communication technologies alone will not solve this problem. Utilities need effective methods to exploit and use the hidden opportunities and knowledge residing in unexplored data resources. Superior performance before, during and after outages depends upon the right information being available at the right time to the right people. Acquisition of raw data is the easy part; instead, it is the ability to use advanced analytical, data processing and data

  8. Permanent start-up instrumentation for maintenance outages

    Energy Technology Data Exchange (ETDEWEB)

    Cuttler, J.M. [Cuttler and Associates Inc., Mississauga, Ontario (Canada); Nasimi, E.; Gill, H.; Scrannage, R.; Paquette, P. [Bruce Power, Tiverton, Ontario (Canada)

    2011-07-01

    This paper assesses the need and feasibility of permanent start-up instrumentation detectors to monitor photoneutron flux during maintenance outages. CANDU ion chamber systems were designed to remain on scale for ten weeks after reactor shutdown. A requirement was imposed in the mid-1990s to put the reactor into an overpoisoned guaranteed shutdown state whenever it is shut down and not actively undergoing a restart. Due to the high gadolinium concentration, the ion chamber systems go off scale within three weeks. Operating policies and procedures require the neutron flux and its rate of change to be monitored when fuel is in the reactor. (author)

  9. Evaluation of impact of backbone outages in IP networks

    Science.gov (United States)

    Kogan, Yaakov; Choudhury, Gagan L.; Tarapore, Percy

    2004-09-01

    Nationwide IP networks typically include nodes in major cities and the following elements: customer equipment, access routers, backbone routers, peering routers, access links connecting customer equipment to access routers, access routers to backbone routers, and backbone links interconnecting backbone routers. The part of this network consisting of backbone routers and related interconnecting links is referred to as the "backbone". We develop a new approach for accurately computing the Availability measure of IP networks by directly simulating each type of backbone outage event and its impact on traffic loss. We use this approach to quantify availability improvement as a result of introducing various technological changes in the network such as IGP tuning, high availability router architecture, MPLS-TE and Fast Reroute. A situation, where operational backbone links do not have enough spare capacity to carry additional traffic during the outage time, is referred to as bandwidth loss. We concentrate on one unidirectional backbone link and derive asymptotic approximations for the expected bandwidth loss in the framework of generalized Erlang and Engset models when the total number of resource units and request arrival rates are proportionally large. Simulation results demonstrate good accuracy of the approximations.

  10. APPROACH TO ASSESSING THE PREPAREDNESS OF HOSPITALS TO POWER OUTAGES

    Directory of Open Access Journals (Sweden)

    Lenka BREHOVSKÁ

    2017-06-01

    Full Text Available Within the secondary impacts of electricity blackouts, it is necessary to pay attention to facilities providing medical care for the population, namely the hospitals. Hospitals represent a key position in the provision of health care also in times of crisis. These facilities must provide constant care; it is therefore essential that the preparedness of such facilities is kept at a high level. The basic aim of this article is to analyse the preparedness of hospitals to power outages (power failures, blackouts within a pilot study. On that basis, a SWOT analysis is used to determine strengths and weaknesses of the system of preparedness of hospitals to power outages and solutions for better security of hospitals are defined. The sample investigated consists of four hospitals founded by the Regional Authority (hospitals Nos. 1-4 and one hospital founded by the Ministry of Health of the Czech Republic (hospital No. 5. The results of the study shows that most weaknesses of the preparedness of hospitals are represented by inadequately addressed reserves of fuel for the main backup power supply, poor knowledge of employees who are insufficiently retrained, and old backup power supplies (even 35 years in some cases.

  11. Outage Analysis of Asymmetric RF-FSO Systems

    KAUST Repository

    Ansari, Imran Shafique

    2017-03-20

    In this work, the outage performance analysis of a dual-hop transmission system composed of asymmetric radio frequency (RF) channels cascaded with free-space optical (FSO) links is presented. The RF links are modeled by the Rayleigh fading distribution and the FSO links are modeled by Malaga (M) turbulence distribution. The FSO links account for pointing errors and both types of detection techniques (i.e. heterodyne detection as well as intensity modulation/direct detection (IM/DD)). Transmit diversity is applied at the source, selection combining is applied at the destination, and the relay is equipped with single RF receive antenna and single aperture for relaying the information over FSO links. With this model, a new exact closed-form expression is derived for the outage probability of the end-to- end signal-to-noise ratio of such communication systems in terms of the Meijer\\'s G function under fixed amplify-and-forward relay scheme. All new analytical results are verified via computer-based Monte-Carlo simulations and are illustrated by some selected numerical results.

  12. Outage analysis for underlay cognitive networks using incremental regenerative relaying

    KAUST Repository

    Tourki, Kamel

    2013-02-01

    Cooperative relay technology has recently been introduced into cognitive radio (CR) networks to enhance the network capacity, scalability, and reliability of end-to-end communication. In this paper, we investigate an underlay cognitive network where the quality of service (QoS) of the secondary link is maintained by triggering an opportunistic regenerative relaying once it falls under an unacceptable level. Analysis is conducted for two schemes, referred to as the channel-state information (CSI)-based and fault-tolerant schemes, respectively, where different amounts of CSI were considered. We first provide the exact cumulative distribution function (cdf) of the received signal-to-noise ratio (SNR) over each hop with colocated relays. Then, the cdf\\'s are used to determine a very accurate closed-form expression for the outage probability for a transmission rate $R$. In a high-SNR region, a floor of the secondary outage probability occurs, and we derive its corresponding expression. We validate our analysis by showing that the simulation results coincide with our analytical results in Rayleigh fading channels. © 1967-2012 IEEE.

  13. Results of NASA/DARPA Automatic Probe and Drogue Refueling Flight Test

    Science.gov (United States)

    Schweikhard, Keith

    2008-01-01

    This slide presentation reviews the flight test from the autonomous airborne refueling system. It includes information on the prototype system that can autonomously perform fueling, including during a turn or mild turbulence, and the autonomous rendezvous capability.

  14. Refueling Infrastructure for Alternative Fuel Vehicles: Lessons Learned for Hydrogen; Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Melaina, M. W.; McQueen, S.; Brinch, J.

    2008-07-01

    DOE sponsored the Refueling Infrastructure for Alternative Fuel Vehicles: Lessons Learned for Hydrogen workshop to understand how lessons from past experiences can inform future efforts to commercialize hydrogen vehicles. This report contains the proceedings from the workshop.

  15. Economic and technical analysis of distributed utility benefits for hydrogen refueling stations

    Energy Technology Data Exchange (ETDEWEB)

    Iannucci, J.J.; Eyer, J.M.; Horgan, S.A. [Distributed Utility Associates, Livermore, CA (United States); Schoenung, S.M. [Longitude 122 West, Inc., Menlo Park, CA (United States)

    1998-08-01

    This paper discusses the potential economic benefits of operating hydrogen refueling stations to supplying pressurized hydrogen for vehicles, and supplying distributed utility generation, transmission and distribution peaking needs to the utility. The study determined under what circumstances using a hydrogen-fueled generator as a distributed utility generation source, co-located with the hydrogen refueling station components (electrolyzer and storage), would result in cost savings to the station owner, and hence lower hydrogen production costs.

  16. Refueling emissions from cars in Japan: Compositions, temperature dependence and effect of vapor liquefied collection system

    Science.gov (United States)

    Yamada, Hiroyuki; Inomata, Satoshi; Tanimoto, Hiroshi

    2015-11-01

    Refueling emissions from cars available on the Japanese market, which were not equipped with specific controlling devices, were investigated. For the composition analysis, a proton transfer reaction plus switchable reagent ion mass spectrometry (PTR + SRI-MS), which is capable of real-time measurement, was used. In addition, the performance of a vapor liquefied collection system (VLCS), which is a recently developed controlling device, was evaluated and compared with an onboard refueling vapor recovery (ORVR) system. The refueling emission factor of uncontrolled vehicles at 20 °C was 1.02 ± 0.40 g/L in the case dispensing 20 L of fuel. The results of composition analysis indicated that the maximum incremental reactivity (MIR) of refueling emissions in Japan was 3.49 ± 0.83. The emissions consist of 80% alkanes and 20% alkenes, and aromatics and di-enes were negligible. C4 alkene had the highest impact on the MIR of refueling emissions. The amounts of refueling emissions were well reproduced by a function developed by MOVE2010 in the temperature range of 5-35 °C. The compositions of the refueling emissions varied in this temperature range, but the change in MIR was negligible. The trapping efficiency of VLCS was the same level as that of the ORVR (over 95%). The MIRs of refueling and evaporative emissions were strongly affected by that of the test fuel. This study and our previous study indicated that MIRbreakthrough ≈ MIRrefueling ≈ MIRfuel + 0.5 and MIRpermeation ≈ MIRfuel. The real-world estimated average MIRfuel in Japan was about 3.0.

  17. Effect of mass variation on the dynamics of receiver aircraft during aerial refueling

    Science.gov (United States)

    Mao, Weixin

    This dissertation presents the results of a study of the dynamic behavior of two aircraft that are flying in formation while one of them (the receiver) is being refueled by the other (the tanker) in mid-flight. The current procedure for aerial refueling requires that the receiver aircraft fly below, behind, and in relatively close proximity of the tanker for refueling to be possible. This means that the receiver aircraft is subjected to the full impact of the tanker wake turbulence; and this can clearly have a major impact on the motion of the receiver craft. Another important fact about aerial refueling is that large quantity of fuel is transferred from one vehicle to the other in a relatively short time. The resulting change in mass and the attendant change in aircraft inertia properties can also affect the dynamics of the aircraft system during fuel transfer. The principal goal of this project is to investigate the importance of this latter effect. This work accomplishes two main objectives. First, it shows how mass variation can be effectively factored into an analytical study of in-flight refueling; and it does this while keeping the analyses involved manageable. In addition, a numerical study of the equations of motion is utilized to extract useful information on how mass variation and some changes in receiver aircraft parameters can affect the motion of the receiver relative to the tanker. Results obtained indicate that mass variation due to fuel transfer compounds the difficulties created by tanker wake turbulence. In order to keep the receiver aircraft at a fixed position relative to the tanker during aerial refueling, appreciable adjustments must be made to the receiver's angle of attack, throttle setting and elevator deflection. A larger refueling rate demands even larger adjustments. Changes in certain other parameters related to aerial refueling can also amplify the effects of mass variation on the receiver motion, or influence the system's dynamics in

  18. Seasonal and Local Characteristics of Lightning Outages of Power Distribution Lines in Hokuriku Area

    Science.gov (United States)

    Sugimoto, Hitoshi; Shimasaki, Katsuhiko

    The proportion of the lightning outages in all outages on Japanese 6.6kV distribution lines is high with approximately 20 percent, and then lightning protections are very important for supply reliability of 6.6kV lines. It is effective for the lightning performance to apply countermeasures in order of the area where a large number of the lightning outages occur. Winter lightning occurs in Hokuriku area, therefore it is also important to understand the seasonal characteristics of the lightning outages. In summer 70 percent of the lightning outages on distribution lines in Hokuriku area were due to sparkover, such as power wire breakings and failures of pole-mounted transformers. However, in winter almost half of lightning-damaged equipments were surge arrester failures. The number of the lightning outages per lightning strokes detected by the lightning location system (LLS) in winter was 4.4 times larger than that in summer. The authors have presumed the occurrence of lightning outages from lightning stroke density, 50% value of lightning current and installation rate of lightning protection equipments and overhead ground wire by multiple regression analysis. The presumed results suggest the local difference in the lightning outages.

  19. 77 FR 25088 - Extension of the Commission's Rules Regarding Outage Reporting to Interconnected Voice Over...

    Science.gov (United States)

    2012-04-27

    ... reporting requirements of the Commission's rules to interconnected Voice over Internet Protocol (VoIP... service. Unlike other outages of voice service, VoIP outages are not reported to the Commission because... clearly imposes a ``duty'' on ``each IP-enabled voice service [interconnected VoIP] provider to provide 9...

  20. Outage probability of opportunistic decode-and-forward relaying over Nakagami-m fading channels

    Institute of Scientific and Technical Information of China (English)

    CHUAI Gang; ZHANG Bao-zhi; LIU Xing-mei; GAO Li

    2009-01-01

    In this article, the outage probability behavior of a relay network over Nakagami-m fading channels is analyzed. Both reactive and proactive opportunistic decode-and-forward (DAF) strategies are considered. The closed-form solutions to the outage probabilities on both opportunistic DAF strategies are derived. Simulation results conf'Lrrn the presented mathematical analysis.

  1. 76 FR 33686 - Proposed Extension of Part 4 of the Commission's Rules Regarding Outage Reporting to...

    Science.gov (United States)

    2011-06-09

    ... VoIP architectures? Do the Real-time Transport Control Protocol (RTCP) round-trip and Session... trigger outage reporting? There are differences in the various architectures of different types of..., accurate reporting. 41. We note that Japan requires outage reporting from broadband communications...

  2. A repeatedly refuelable mediated biofuel cell based on a hierarchical porous carbon electrode

    Science.gov (United States)

    Fujita, Shuji; Yamanoi, Shun; Murata, Kenichi; Mita, Hiroki; Samukawa, Tsunetoshi; Nakagawa, Takaaki; Sakai, Hideki; Tokita, Yuichi

    2014-05-01

    Biofuel cells that generate electricity from renewable fuels, such as carbohydrates, must be reusable through repeated refuelling, should these devices be used in consumer electronics. We demonstrate the stable generation of electricity from a glucose-powered mediated biofuel cell through multiple refuelling cycles. This refuelability is achieved by immobilizing nicotinamide adenine dinucleotide (NAD), an electron-transfer mediator, and redox enzymes in high concentrations on porous carbon particles constituting an anode while maintaining their electrochemical and enzymatic activities after the immobilization. This bioanode can be refuelled continuously for more than 60 cycles at 1.5 mA cm-2 without significant potential drop. Cells assembled with these bioanodes and bilirubin-oxidase-based biocathodes can be repeatedly used to power a portable music player at 1 mW cm-3 through 10 refuelling cycles. This study suggests that the refuelability within consumer electronics should facilitate the development of long and repeated use of the mediated biofuel cells as well as of NAD-based biosensors, bioreactors, and clinical applications.

  3. Home Use Devices: How to Prepare for and Handle Power Outages for Medical Devices That Require Electricity

    Science.gov (United States)

    ... Handle Power Outages for Medical Devices that Require Electricity Center for De CDRH vices and Rad lth ... Handle Power Outages for Medical Devices that Require Electricity As a home medical device user, it is ...

  4. Outage Probability and Power Allocation for Two-Way DF Relay Networks with Relay Selection

    Directory of Open Access Journals (Sweden)

    Z. Fan

    2012-09-01

    Full Text Available In this paper, we investigate the outage probability and power allocation for the two-way decode-and-forward (DF relay networks with relay selection.~Specially, we consider independent but not necessarily identical distributed Rayleigh fading channels. Firstly, we derive an exact closed form outage probability expression. To shed light on the relation between the outage probability and the power allocation factor, an upper bound for the outage probability is derived, too. We then propose a power allocation scheme in the sense of minimizing this upper bound. Monte Carlo simulations are conducted to show that the derived outage probability expression excellently matches simulation results, and our proposed power allocation scheme performs effectively.

  5. Estimating Power Outage Cost based on a Survey for Industrial Customers

    Science.gov (United States)

    Yoshida, Yoshikuni; Matsuhashi, Ryuji

    A survey was conducted on power outage cost for industrial customers. 5139 factories, which are designated energy management factories in Japan, answered their power consumption and the loss of production value due to the power outage in an hour in summer weekday. The median of unit cost of power outage of whole sectors is estimated as 672 yen/kWh. The sector of services for amusement and hobbies and the sector of manufacture of information and communication electronics equipment relatively have higher unit cost of power outage. Direct damage cost from power outage in whole sectors reaches 77 billion yen. Then utilizing input-output analysis, we estimated indirect damage cost that is caused by the repercussion of production halt. Indirect damage cost in whole sectors reaches 91 billion yen. The sector of wholesale and retail trade has the largest direct damage cost. The sector of manufacture of transportation equipment has the largest indirect damage cost.

  6. Underlay Cognitive Radio Systems with Improper Gaussian Signaling: Outage Performance Analysis

    KAUST Repository

    Amin, Osama

    2016-03-29

    Improper Gaussian signaling has the ability over proper (conventional) Gaussian signaling to improve the achievable rate of systems that suffer from interference. In this paper, we study the impact of using improper Gaussian signaling on the performance limits of the underlay cognitive radio system by analyzing the achievable outage probability of both the primary user (PU) and secondary user (SU). We derive the exact outage probability expression of the SU and construct upper and lower bounds of the PU outage probability which results in formulating an approximate expression of the PU outage probability. This allows us to design the SU signal by adjusting its transmitted power and the circularity coefficient to minimize the SU outage probability while maintaining a certain PU quality-of-service. Finally, we evaluate the derived expressions for both the SU and the PU and the corresponding adaptive algorithms by numerical results.

  7. Outage analysis for underlay relay-assisted cognitive networks

    KAUST Repository

    Tourki, Kamel

    2012-12-01

    Cooperative relay technology was recently introduced into cognitive radio networks in order to enhance network capacity, scalability, and reliability of end-to-end communication. In this paper, we investigate an underlay cognitive network where the quality of service of the secondary link is maintained by triggering an opportunistic regenerative relaying once it falls under an unacceptable level. We first provide the exact cumulative density function (CDF) of received signal-to-noise (SNR) over each hop with co-located relays. Then, the CDFs are used to determine very accurate closed-form expression for the outage probability for a transmission rate R. We validate our analysis by showing that simulation results coincide with our analytical results in Rayleigh fading channels. © 2012 IEEE.

  8. Asymmetric Hardware Distortions in Receive Diversity Systems: Outage Performance Analysis

    KAUST Repository

    Javed, Sidrah

    2017-02-22

    This paper studies the impact of asymmetric hardware distortion (HWD) on the performance of receive diversity systems using linear and switched combining receivers. The asymmetric attribute of the proposed model motivates the employment of improper Gaussian signaling (IGS) scheme rather than the traditional proper Gaussian signaling (PGS) scheme. The achievable rate performance is analyzed for the ideal and non-ideal hardware scenarios using PGS and IGS transmission schemes for different combining receivers. In addition, the IGS statistical characteristics are optimized to maximize the achievable rate performance. Moreover, the outage probability performance of the receive diversity systems is analyzed yielding closed form expressions for both PGS and IGS based transmission schemes. HWD systems that employ IGS is proven to efficiently combat the self interference caused by the HWD. Furthermore, the obtained analytic expressions are validated through Monte-Carlo simulations. Eventually, non-ideal hardware transceivers degradation and IGS scheme acquired compensation are quantified through suitable numerical results.

  9. The Magnetic Shielding Effect of a Re-Fuelling Pellet

    DEFF Research Database (Denmark)

    Chang, C. T.

    1975-01-01

    The magnetic shielding effect of a refuelling pellet is considered by first briefly reviewing the existing balloon model. The limitation of the model is pointed out and discussed. Since solid deuterium is an insulator and the ablated plasma is expected to be cold and dense, it is felt...... that the existence of a field-free balloon is questionable; rather some field will be trapped by the pellet. On the assumption that the flow of the ablated plasma is governed by a flexible magnetic nozzle, it is shown that the reduction of the ablation rate of the pellet is not due to the exclusion of the field...... by a balloon, but to the reduction of the ablated plasma pressure through the trapping of the field inside the nozzle. The model also indicates that the penetration of a mm-size pellet into the centre of a low-β reactor might be possible, provided an injection speed around 104 m centerdots−1 can be attained...

  10. Power outages, extreme events and health: a systematic review of the literature from 2011-2012.

    Science.gov (United States)

    Klinger, Chaamala; Landeg, Owen; Murray, Virginia

    2014-01-02

    Background Extreme events (e.g. flooding) threaten critical infrastructure including power supplies. Many interlinked systems in the modern world depend on a reliable power supply to function effectively. The health sector is no exception, but the impact of power outages on health is poorly understood. Greater understanding is essential so that adverse health impacts can be prevented and/or mitigated. Methods We searched Medline, CINAHL and Scopus for papers about the health impacts of power outages during extreme events published in 2011-2012. A thematic analysis was undertaken on the extracted information. The Public Health England Extreme Events Bulletins between 01/01/2013 - 31/03/2013 were used to identify extreme events that led to power outages during this three-month period. Results We identified 20 relevant articles. Power outages were found to impact health at many levels within diverse settings. Recurrent themes included the difficulties of accessing healthcare, maintaining frontline services and the challenges of community healthcare. We identified 52 power outages in 19 countries that were the direct consequence of extreme events during the first three months of 2013. Conclusions To our knowledge, this is the first review of the health impacts of power outages. We found the current evidence and knowledge base to be poor. With scientific consensus predicting an increase in the frequency and magnitude of extreme events due to climate change, the gaps in knowledge need to be addressed in order to mitigate the impact of power outages on global health.

  11. Interglacial Durations

    Science.gov (United States)

    Mangili, Clara; McManus, Jerry F.; Raynaud, Dominique

    2014-05-01

    In the context of future global warming induced by human activities, it is essential to assess the role of natural climatic variations. Precise knowledge of the duration of past interglacial periods is fundamental to the understanding of the potential future evolution of the Holocene. Past ice age cycles provide a natural laboratory for exploring the progression and duration of interglacial climate. Palaeorecords from ice, land and oceans extend over the last 800 ka, revealing eight glacial-interglacial cycles, with a range of insolation and greenhouse gas influences. The interglacials display a correspondingly large variety of intensity and duration, thus providing an opportunity for major insights into the mechanisms involved in the behaviour of interglacial climates. A comparison of the duration of these interglacials, however, is often difficult, as the definition of an interglacial depends on the archive that is considered. Therefore, to compare interglacial length and climate conditions from different archives, a consistent definition of interglacial conditions is required, ideally one that is not bound to the method nor to the archive under consideration. Here we present a method to identify interglacials and to calculate their length by mean of a simple statistical approach. We based our method on ~ 400 ka windows of time to determine mean climatic conditions while allowing for the possibility of long term evolution of the climatic baseline. For our study of interglacials of the past 800 ka, we used two windows that largely align with the pre- (800-430 ka ago) and post- (430-0 ka ago) mid-Brunhes event (MBE), although the resulting conclusions are not sensitive to this particular division. We applied this method to the last 800 ka of a few palaeoclimate records: the deuterium ice core (EDC) record as a climatic proxy, the benthic δ18O stack (LR04) as a proxy for sea level/ice volume, ice core (Vostok, EDC) atmospheric CO2 and additional records. Although

  12. An analytical model for evaluating outage and handover probability of cellular wireless networks

    CERN Document Server

    Decreusefond, Laurent; Vu, Than-Tung

    2010-01-01

    We consider stochastic cellular networks where base stations locations form a homogenous Poisson point process and each mobile is attached to the base station that provides the best mean signal power. The mobile is in outage if the SINR falls below some threshold. The handover decision has to be made if the mobile is in outage for some time slots. The outage probability and the handover probability is evaluated in taking into account the effect of path loss, shadowing, Rayleigh fast fading, frequency factor reuse and conventional beamforming. The main assumption is that the Rayleigh fast fading changes each time slot while other network components remain static during the period of study.

  13. Investigation of Suitability of Cascading Outage Assessment Methods for Real-Time Assessment

    DEFF Research Database (Denmark)

    Petersen, Pauli Fríðheim; Jóhannsson, Hjörtur; Nielsen, Arne Hejde

    of the method to real-time assessment. The investigation revealed that two of the methods are of special interest for further study on real-time assessment of cascading outages. These are the betweenness centrality model, based on network topology, and the manchester model, based on AC power flow.......This paper investigates the suitability of assessment methods for cascading outages for real-time assessment. A total of ten assessment methods for cascading outages are investigated, and for all of the investigated methods a complexity assessment is performed to assess the suitability...

  14. Vision-based Estimation of Relative Pose in Autonomous Aerial Refueling

    Institute of Scientific and Technical Information of China (English)

    DING Meng; WEI Li; WANG Bangfeng

    2011-01-01

    The lack of autonomous aerial refueling capabilities is one of the greatest limitations of unmanned aerial vehicles.This paper discusses the vision-based estimation of the relative pose of a tanker and unmanned aerial vehicle,which is a key issue in autonomous aerial refueling.The main task of this paper is to study the relative pose estimation for a tanker and unmanned aerial vehicle in the phase of commencing refueling and during refueling.The employed algorithm includes the initialization of the orientation parameters and an orthogonal iteration algorithm to estimate the optimal solution of rotation matrix and translation vector.In simulation experiments,because of the small variation in the rotation angle in aerial refueling,the method in which the initial rotation matrix is the identity matrix is found to be the most stable and accurate among methods.Finally,the paper discusses the effects of the number and configuration of feature points on the accuracy of the estimation results when using this method.

  15. Optimization of hydrogen stations in Florida using the Flow-Refueling Location Model

    Energy Technology Data Exchange (ETDEWEB)

    Kuby, Michael; Kim, Jong-Geun [School of Geographical Sciences, Arizona State University, Tempe, AZ 85287-5302 (United States); Lines, Lee [Department of Environmental Studies, Rollins College, 1000 Holt Ave., Box 2753, Winter Park, FL 32789-4499 (United States); Schultz, Ronald; Xie, Zhixiao [Department of Geosciences, Florida Atlantic University, Boca Raton, FL 33431 (United States); Lim, Seow [Salt River Project, 1521 N. Project Drive, Tempe, AZ 85281-1298 (United States)

    2009-08-15

    This paper develops and applies a model that locates hydrogen stations to refuel the maximum volume of vehicle flows. Inputs to the model include a road network with average speeds; the origin-destination flow volumes between each origin and destination; a maximum driving range between refueling stops; and the number of stations to build. The Flow-Refueling Location Model maximizes the flow volumes that can be refueled, measured either in number of trips or vehicle-miles traveled. Geographic Information Systems and heuristic algorithms are integrated in a spatial decision support system that researchers can use to develop data, enter assumptions, analyze scenarios, evaluate tradeoffs, and map results. For the Florida Hydrogen Initiative, we used this model to investigate strategies for rolling out an initial refueling infrastructure in Florida at two different scales of analysis: metropolitan Orlando and statewide. By analyzing a variety of scenarios at both scales of analysis, we identify a robust set of stations that perform well under a variety of assumptions, and develop a strategy for phasing in clustered and connecting stations in several stages or tiers. (author)

  16. Power outage estimation for tropical cyclones: improved accuracy with simpler models.

    Science.gov (United States)

    Nateghi, Roshanak; Guikema, Seth; Quiring, Steven M

    2014-06-01

    In this article, we discuss an outage-forecasting model that we have developed. This model uses very few input variables to estimate hurricane-induced outages prior to landfall with great predictive accuracy. We also show the results for a series of simpler models that use only publicly available data and can still estimate outages with reasonable accuracy. The intended users of these models are emergency response planners within power utilities and related government agencies. We developed our models based on the method of random forest, using data from a power distribution system serving two states in the Gulf Coast region of the United States. We also show that estimates of system reliability based on wind speed alone are not sufficient for adequately capturing the reliability of system components. We demonstrate that a multivariate approach can produce more accurate power outage predictions.

  17. An approach to implement PSO to optimize outage probability of coded cooperative communication with multiple relays

    Directory of Open Access Journals (Sweden)

    Sindhu Hak Gupta

    2016-09-01

    Full Text Available Coded Cooperative Communication is a novel concept and it is the solution to utilize the benefits of MIMO (Multiple Input Multiple Output gains on distributed scale. In this paper the outage behavior of coded cooperative communication with multiple relays is examined. The numerical expression for outage probability is derived. Nakagami-m fading statics is considered. Outage probability is observed to be function of various free and constrained parameters. An approach is presented to implement PSO and optimize the free parameters on which outage probability of coded cooperative communication with multiple relay depends. Analytical and Matlab simulation results reveal that the proposed technique outperforms Non Optimized technique and exhibit a promising performance.

  18. Outage Capacity Analysis of TAS/MRC Systems over Arbitrary Nakagami-m Fading Channels

    Science.gov (United States)

    Hung, Chia-Chun; Chiang, Ching-Tai; Lin, Shyh-Neng; Wu, Rong-Ching

    A simple closed-form approximation for the outage capacity of Transmit Antenna Selection/Maximal-Ratio Combining (TAS/MRC) systems over independent and identically distributed (i.i.d) Nakagami-m fading channels is derived while the fading index is a positive integer. When the Nakagami-m fading index is not an integer, the approximate outage capacity is derived as a single infinite series of Gamma function. Computer simulations verify the accuracy of the approximate results.

  19. Outage Analysis of Spectrum-Sharing over M-Block Fading with Sensing Information

    KAUST Repository

    Alabbasi, Abdulrahman

    2016-07-13

    Future wireless technologies, such as, 5G, are expected to support real-time applications with high data throughput, e.g., holographic meetings. From a bandwidth perspective, cognitive radio is a promising technology to enhance the system’s throughput via sharing the licensed spectrum. From a delay perspective, it is well known that increasing the number of decoding blocks will improve the system robustness against errors, while increasing the delay. Therefore, optimally allocating the resources to determine the tradeoff of tuning the length of decoding blocks while sharing the spectrum is a critical challenge for future wireless systems. In this work, we minimize the targeted outage probability over the block-fading channels while utilizing the spectrum-sharing concept. The secondary user’s outage region and the corresponding optimal power are derived, over twoblocks and M-blocks fading channels. We propose two suboptimal power strategies and derive the associated asymptotic lower and upper bounds on the outage probability with tractable expressions. These bounds allow us to derive the exact diversity order of the secondary user’s outage probability. To further enhance the system’s performance, we also investigate the impact of including the sensing information on the outage problem. The outage problem is then solved via proposing an alternating optimization algorithm, which utilizes the verified strict quasiconvex structure of the problem. Selected numerical results are presented to characterize the system’s behavior and show the improvements of several sharing concepts.

  20. Estimating the Propagation of Interdependent Cascading Outages With Multi-Type Branching Processes

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Junjian; Yu, Wenyun; Sun, Kai

    2017-03-01

    In this paper, the multi-type branching process is applied to describe the statistics and interdependencies of line outages, the load shed, and isolated buses. The offspring mean matrix of the multi-type branching process is estimated by the Expectation Maximization (EM) algorithm and can quantify the extent of outage propagation. The joint distribution of two types of outages is estimated by the multi-type branching process via the Lagrange-Good inversion. The proposed model is tested with data generated by the AC OPA cascading simulations on the IEEE 118-bus system. The largest eigenvalues of the offspring mean matrix indicate that the system is closer to criticality when considering the interdependence of different types of outages. Compared with empirically estimating the joint distribution of the total outages, good estimate is obtained by using the multitype branching process with a much smaller number of cascades, thus greatly improving the efficiency. It is shown that the multitype branching process can effectively predict the distribution of the load shed and isolated buses and their conditional largest possible total outages even when there are no data of them.

  1. Synergistic Use of Nighttime Satellite Data, Electric Utility Infrastructure, and Ambient Population to Improve Power Outage Detections in Urban Areas

    Directory of Open Access Journals (Sweden)

    Tony A. Cole

    2017-03-01

    Full Text Available Natural and anthropogenic hazards are frequently responsible for disaster events, leading to damaged physical infrastructure, which can result in loss of electrical power for affected locations. Remotely-sensed, nighttime satellite imagery from the Suomi National Polar-orbiting Partnership (Suomi-NPP Visible Infrared Imaging Radiometer Suite (VIIRS Day/Night Band (DNB can monitor power outages in disaster-affected areas through the identification of missing city lights. When combined with locally-relevant geospatial information, these observations can be used to estimate power outages, defined as geographic locations requiring manual intervention to restore power. In this study, we produced a power outage product based on Suomi-NPP VIIRS DNB observations to estimate power outages following Hurricane Sandy in 2012. This product, combined with known power outage data and ambient population estimates, was then used to predict power outages in a layered, feedforward neural network model. We believe this is the first attempt to synergistically combine such data sources to quantitatively estimate power outages. The VIIRS DNB power outage product was able to identify initial loss of light following Hurricane Sandy, as well as the gradual restoration of electrical power. The neural network model predicted power outages with reasonable spatial accuracy, achieving Pearson coefficients (r between 0.48 and 0.58 across all folds. Our results show promise for producing a continental United States (CONUS- or global-scale power outage monitoring network using satellite imagery and locally-relevant geospatial data.

  2. [CFD numerical simulation onto the gas-liquid two-phase flow behavior during vehicle refueling process].

    Science.gov (United States)

    Chen, Jia-Qing; Zhang, Nan; Wang, Jin-Hui; Zhu, Ling; Shang, Chao

    2011-12-01

    With the gradual improvement of environmental regulations, more and more attentions are attracted to the vapor emissions during the process of vehicle refueling. Research onto the vehicle refueling process by means of numerical simulation has been executed abroad since 1990s, while as it has never been involved so far domestically. Through reasonable simplification about the physical system of "Nozzle + filler pipe + gasoline storage tank + vent pipe" for vehicle refueling, and by means of volume of fluid (VOF) model for gas-liquid two-phase flow and Re-Normalization Group kappa-epsilon turbulence flow model provided in commercial computational fluid dynamics (CFD) software Fluent, this paper determined the proper mesh discretization scheme and applied the proper boundary conditions based on the Gambit software, then established the reasonable numerical simulation model for the gas-liquid two-phase flow during the refueling process. Through discussing the influence of refueling velocity on the static pressure of vent space in gasoline tank, the back-flowing phenomenon has been revealed in this paper. It has been demonstrated that, the more the flow rate and the refueling velocity of refueling nozzle is, the higher the gross static pressure in the vent space of gasoline tank. In the meanwhile, the variation of static pressure in the vent space of gasoline tank can be categorized into three obvious stages. When the refueling flow rate becomes higher, the back-flowing phenomenon of liquid gasoline can sometimes be induced in the head section of filler pipe, thus making the gasoline nozzle pre-shut-off. Totally speaking, the theoretical work accomplished in this paper laid some solid foundation for self-researching and self-developing the technology and apparatus for the vehicle refueling and refueling emissions control domestically.

  3. Human Factors and Modeling Methods in the Development of Control Room Modernization Concepts

    Energy Technology Data Exchange (ETDEWEB)

    Hugo, Jacques V.; Slay III, Lorenzo

    2017-06-01

    nuclear power plants. Although the nuclear industry has made steady improvement in outage optimization, each day of a refueling outage still represents an opportunity to save millions of dollars and each day an outage extends past its planned end date represents millions of dollars that may have been spent unnecessarily. Reducing planned outage duration or preventing outage extensions requires careful management of the outage schedule as well as constant oversight and monitoring of work completion during the outage execution. During a typical outage, there are typically more than 10,000 activities on the schedule that, if not managed efficiently, may cause expensive outage delays. Management of outages currently relies largely on paper-based resources and general-purpose office software. A typical tool currently used to monitor work performance is a burn-down curve, where total remaining activities are plotted against the baseline schedule to track bulk work completion progress. While these tools are useful, there is still considerable uncertainty during a typical outage that bulk work progress is adequate and therefore a lot of management time is spent analyzing the situation on a daily basis. This paper describes recent advances made in developing a framework for the design of visual outage information presentation, as well as an overview of the scientific principles that informed the development of the visualizations. To test the utility of advanced visual outage information presentation, an outage management dashboard software application was created as part of the Department of Energy’s Advanced Outage Control Center project. This dashboard is intended to present all the critical information an outage manager would need to understand the current status of a refueling outage. The dashboard presents the critical path, bulk work performance, key performance indicators, outage milestones and metrics relating current performance to historical performance

  4. Earth-Space Links and Fade-Duration Statistics

    Science.gov (United States)

    Davarian, Faramaz

    1996-01-01

    In recent years, fade-duration statistics have been the subject of several experimental investigations. A good knowledge of the fade-duration distribution is important for the assessment of a satellite communication system's channel dynamics: What is a typical link outage duration? How often do link outages exceeding a given duration occur? Unfortunately there is yet no model that can universally answer the above questions. The available field measurements mainly come from temperate climatic zones and only from a few sites. Furthermore, the available statistics are also limited in the choice of frequency and path elevation angle. Yet, much can be learned from the available information. For example, we now know that the fade-duration distribution is approximately lognormal. Under certain conditions, we can even determine the median and other percentiles of the distribution. This paper reviews the available data obtained by several experimenters in different parts of the world. Areas of emphasis are mobile and fixed satellite links. Fades in mobile links are due to roadside-tree shadowing, whereas fades in fixed links are due to rain attenuation.

  5. Outage Probability Minimization for Energy Harvesting Cognitive Radio Sensor Networks

    Directory of Open Access Journals (Sweden)

    Fan Zhang

    2017-01-01

    Full Text Available The incorporation of cognitive radio (CR capability in wireless sensor networks yields a promising network paradigm known as CR sensor networks (CRSNs, which is able to provide spectrum efficient data communication. However, due to the high energy consumption results from spectrum sensing, as well as subsequent data transmission, the energy supply for the conventional sensor nodes powered by batteries is regarded as a severe bottleneck for sustainable operation. The energy harvesting technique, which gathers energy from the ambient environment, is regarded as a promising solution to perpetually power-up energy-limited devices with a continual source of energy. Therefore, applying the energy harvesting (EH technique in CRSNs is able to facilitate the self-sustainability of the energy-limited sensors. The primary concern of this study is to design sensing-transmission policies to minimize the long-term outage probability of EH-powered CR sensor nodes. We formulate this problem as an infinite-horizon discounted Markov decision process and propose an ϵ-optimal sensing-transmission (ST policy through using the value iteration algorithm. ϵ is the error bound between the ST policy and the optimal policy, which can be pre-defined according to the actual need. Moreover, for a special case that the signal-to-noise (SNR power ratio is sufficiently high, we present an efficient transmission (ET policy and prove that the ET policy achieves the same performance with the ST policy. Finally, extensive simulations are conducted to evaluate the performance of the proposed policies and the impaction of various network parameters.

  6. Outage Probability Minimization for Energy Harvesting Cognitive Radio Sensor Networks.

    Science.gov (United States)

    Zhang, Fan; Jing, Tao; Huo, Yan; Jiang, Kaiwei

    2017-01-24

    The incorporation of cognitive radio (CR) capability in wireless sensor networks yields a promising network paradigm known as CR sensor networks (CRSNs), which is able to provide spectrum efficient data communication. However, due to the high energy consumption results from spectrum sensing, as well as subsequent data transmission, the energy supply for the conventional sensor nodes powered by batteries is regarded as a severe bottleneck for sustainable operation. The energy harvesting technique, which gathers energy from the ambient environment, is regarded as a promising solution to perpetually power-up energy-limited devices with a continual source of energy. Therefore, applying the energy harvesting (EH) technique in CRSNs is able to facilitate the self-sustainability of the energy-limited sensors. The primary concern of this study is to design sensing-transmission policies to minimize the long-term outage probability of EH-powered CR sensor nodes. We formulate this problem as an infinite-horizon discounted Markov decision process and propose an ϵ-optimal sensing-transmission (ST) policy through using the value iteration algorithm. ϵ is the error bound between the ST policy and the optimal policy, which can be pre-defined according to the actual need. Moreover, for a special case that the signal-to-noise (SNR) power ratio is sufficiently high, we present an efficient transmission (ET) policy and prove that the ET policy achieves the same performance with the ST policy. Finally, extensive simulations are conducted to evaluate the performance of the proposed policies and the impaction of various network parameters.

  7. Demonstration of zinc/air fuel battery to enhance the range and mission of fleet electric vehicles: Preliminary results in the refueling of a multicell module

    Science.gov (United States)

    Cooper, J. F.; Fleming, D.; Keene, L.; Maimoni, A.; Peterman, K.; Koopman, R.

    1994-08-01

    We report progress in an effort to develop and demonstrate a refuelable zinc/air battery for fleet electric vehicle applications. A refuelable module consisting of twelve bipolar cells with internal flow system has been refueled at rates of nearly 4 cells per minute, indicating a refueling time of 10 minutes for a 15 kW, 55 kWh battery. The module is refueled by entrainment of 0.5-mm particles in rapidly flowing electrolyte, which delivers the particles into hoppers above each cell in a parallel-flow hydraulic circuit. The concept of user-recovery is presented as an alternative to centralized service infrastructure during market entry.

  8. OTRA-THS MAC to reduce Power Outage Data Collection Latency in a smart meter network

    Energy Technology Data Exchange (ETDEWEB)

    Garlapati, Shravan K [ORNL; Kuruganti, Phani Teja [ORNL; Buehrer, Richard M [ORNL; Reed, Jeffrey H [ORNL

    2014-01-01

    The deployment of advanced metering infrastructure by the electric utilities poses unique communication challenges, particularly as the number of meters per aggregator increases. During a power outage, a smart meter tries to report it instantaneously to the electric utility. In a densely populated residential/industrial locality, it is possible that a large number of smart meters simultaneously try to get access to the communication network to report the power outage. If the number of smart meters is very high of the order of tens of thousands (metropolitan areas), the power outage data flooding can lead to Random Access CHannel (RACH) congestion. Several utilities are considering the use of cellular network for smart meter communications. In 3G/4G cellular networks, RACH congestion not only leads to collisions, retransmissions and increased RACH delays, but also has the potential to disrupt the dedicated traffic flow by increasing the interference levels (3G CDMA). In order to overcome this problem, in this paper we propose a Time Hierarchical Scheme (THS) that reduces the intensity of power outage data flooding and power outage reporting delay by 6/7th, and 17/18th when compared to their respective values without THS. Also, we propose an Optimum Transmission Rate Adaptive (OTRA) MAC to optimize the latency in power outage data collection. The analysis and simulation results presented in this paper show that both the OTRA and THS features of the proposed MAC results in a Power Outage Data Collection Latency (PODCL) that is 1/10th of the 4G LTE PODCL.

  9. 40 CFR 86.1825-08 - Durability demonstration procedures for refueling emissions.

    Science.gov (United States)

    2010-07-01

    ... must be conducted using the SRC or a road cycle approved under the provisions of § 86.1823(e)(1). (2...: (1) Cycling of canister loading due to diurnal and refueling events; (2) Use of various commercially... paragraph. (h) Emission component durability. . For guidance see 40 CFR 86.1845-01 (e). (i) If...

  10. Validation of Fuqing Nuclear Power Plant Unit 1 Cycle 2 Refueling Design

    Institute of Scientific and Technical Information of China (English)

    PAN; Cui-jie; XIA; Zhao-dong; ZHU; Qing-fu

    2015-01-01

    Fuqing Nuclear Power Plant Unit 1Cycle 2refueling design was validated with the PWR core fuel management package CMS(CASMO5,CMSLINK5and SIMULATE5),including validating fuel management report,validating reload safety evaluation report,validating nuclear design report and validating physics tests report.

  11. Unmanned Carrier-Based Aircraft System: Debate over Systems Role Led to Focus on Aerial Refueling

    Science.gov (United States)

    2016-03-24

    Unmanned Carrier-Based Aircraft System: Debate over System’s Role Led to Focus on Aerial Refueling Prior to February 2016, the Navy had planned to...pages in the publication and whether the publication is printed in color or black and white . Pricing and ordering information is posted on GAO’s

  12. Flight system design for a receiver aircraft to perform autonomous aerial refueling provided with relative position data link

    Science.gov (United States)

    Awni, Kahtan A.

    An automatic aerial refueling system was developed that is capable of controlling the receiving aircraft to rendezvous, dock and station keep the receiver refueling probe in the tanker refueling probe. The automatic refueling system consisted of an active trajectory generator, a guidance system and a control system. The active trajectory generator continuously updated the commanded rendezvous trajectory to be flown by the receiver aircraft. This active trajectory generator concept incorporated design variables that the designer could use to specify the time sequence of the rendezvous and docking maneuver. The output of the trajectory generator was then the command to the flight systems guidance and control systems. To demonstrate this automatic aerial refueling system concept, a detailed design of the flight system algorithms was done for typical aerial refueling mission with a heavy jet tanker aircraft similar to the KC135 and the SIAI-Marchetti S-211 Jet Trainer as a receiver aircraft. The systems gains were selected to minimize the control surface activity while achieving adequate tracking. A simulation was developed that included the flight system algorithms, linear models of the receiver aircraft, atmospheric and tanker wake disturbance models. The performance of the aerial refueling system design was then evaluated in a batch computer simulator. The simulation study demonstrated results showed better disturbance rejection relative to the controller performance while minimizing the utilization of the control surfaces. Results also demonstrated the ability to schedule rendezvous.

  13. Estimating the Propagation of Interdependent Cascading Outages with Multi-Type Branching Processes

    CERN Document Server

    Qi, Junjian; Sun, Kai

    2015-01-01

    In this paper, the multi-type branching process is applied to describe the statistics of line outages, the load shed, and isolated buses. The offspring mean matrix of the multi-type branching process is estimated by the Expectation Maximization (EM) algorithm and can quantify the extent of outage propagation. The joint distribution of two types of outages is estimated by the multi-type branching process via the Lagrange-Good inversion. The proposed model is tested with data generated by the AC OPA cascading simulations on the IEEE 118-bus system. The largest eigenvalues of the offspring mean matrix indicate that the system is closer to criticality when considering the interdependence of different types of outages. Compared with empirically estimating the joint distribution of the total outages, good estimate is obtained by using the multi-type branching process with a much smaller number of cascades, thus greatly improving the efficiency. It is shown that the multi-type branching process can effectively predi...

  14. Evaluation of power outages in Connecticut during hypothetical future Hurricane Sandy scenarios

    Science.gov (United States)

    Wanik, D. W.; Anagnostou, E. N.; Astitha, M.; Frediani, M. E.; Yang, J.

    2015-12-01

    Reliable electric power is a staple of our modern society.The purpose of this work was to evaluate the occurrence of power outages under more intense, future Hurricane Sandy simulations in Connecticut. In addition, we also evaluated how many crews would be necessary to restore power in 7 days, and how different vegetation scenarios might contribute to a decrease in outages. We trained five pairwise models on each current Sandy runs (2012) as training using the random forest model (each validated using 10-fold cross-validation), and used each future Sandy run as an independent test. We predict that a future Sandy would have 2.5x as many outages as current Sandy, which would require 3.23x as many crews as current Sandy to restore power in 7 days. We also found that increased vegetation management might decrease outages, which has implications for both fair-weather and storm days of all types (i.e. blizzards, thunderstorms, ice storms). Although we have only evaluated outages for electric distribution networks, there are many other types (water supply, wastewater, telecommunications) that would likely benefit from an analysis of this type. In addition, given that we have the weather simulations already processed within our 2-km weather simulation domain, we would like to expand our vulnerability analyses to surrounding utilities in New Jersey, New York, Rhode Island, Massachusetts and New Hampshire to facilitate regional coordination among electric distribution networks.

  15. Distributed Power-Line Outage Detection Based on Wide Area Measurement System

    Directory of Open Access Journals (Sweden)

    Liang Zhao

    2014-07-01

    Full Text Available In modern power grids, the fast and reliable detection of power-line outages is an important functionality, which prevents cascading failures and facilitates an accurate state estimation to monitor the real-time conditions of the grids. However, most of the existing approaches for outage detection suffer from two drawbacks, namely: (i high computational complexity; and (ii relying on a centralized means of implementation. The high computational complexity limits the practical usage of outage detection only for the case of single-line or double-line outages. Meanwhile, the centralized means of implementation raises security and privacy issues. Considering these drawbacks, the present paper proposes a distributed framework, which carries out in-network information processing and only shares estimates on boundaries with the neighboring control areas. This novel framework relies on a convex-relaxed formulation of the line outage detection problem and leverages the alternating direction method of multipliers (ADMM for its distributed solution. The proposed framework invokes a low computational complexity, requiring only linear and simple matrix-vector operations. We also extend this framework to incorporate the sparse property of the measurement matrix and employ the LSQRalgorithm to enable a warm start, which further accelerates the algorithm. Analysis and simulation tests validate the correctness and effectiveness of the proposed approaches.

  16. Distributed power-line outage detection based on wide area measurement system.

    Science.gov (United States)

    Zhao, Liang; Song, Wen-Zhan

    2014-07-21

    In modern power grids, the fast and reliable detection of power-line outages is an important functionality, which prevents cascading failures and facilitates an accurate state estimation to monitor the real-time conditions of the grids. However, most of the existing approaches for outage detection suffer from two drawbacks, namely: (i) high computational complexity; and (ii) relying on a centralized means of implementation. The high computational complexity limits the practical usage of outage detection only for the case of single-line or double-line outages. Meanwhile, the centralized means of implementation raises security and privacy issues. Considering these drawbacks, the present paper proposes a distributed framework, which carries out in-network information processing and only shares estimates on boundaries with the neighboring control areas. This novel framework relies on a convex-relaxed formulation of the line outage detection problem and leverages the alternating direction method of multipliers (ADMM) for its distributed solution. The proposed framework invokes a low computational complexity, requiring only linear and simple matrix-vector operations. We also extend this framework to incorporate the sparse property of the measurement matrix and employ the LSQRalgorithm to enable a warm start, which further accelerates the algorithm. Analysis and simulation tests validate the correctness and effectiveness of the proposed approaches.

  17. Achievable Outage Rates In Cognitive Radio Networks under Imperfect Spectrum Sensing

    Directory of Open Access Journals (Sweden)

    N. Tafaghodi Khajavi

    2012-06-01

    Full Text Available In this paper, we aim at deriving the outage rates achieved by the primary user due spectrum sensing in a cognitive radio network, that we call sensing-induced primary outage rates. To reach this goal, in the first step, instead of classical spectrum sensing techniques that evaluate sensing performance only based on correct detection of the presence of the primary user’s signal, we propose a modified framework that also takes into account the correct detection of the absence of primary user’s signal for spectrum sensing performance evaluation. In a second step, we derive the information rates achieved by the coexistence of a primary and a cognitive network. In the last step, assuming slow fading sensing channels, we derive the sensing-induced primary outage rates, i.e., outage rates achieved by the primary network in the presence of a CR with imperfect spectrum sensing, characterized by a given miss-detection probability. Numerical results show that the proposed spectrum sensing outperforms conventional spectrum sensing techniques in terms of primary signal outage rates and total achievable throughputs, without any increase in the cognitive radio complexity.

  18. Coordinated Beamforming for Multiuser MISO Interference Channel under Rate Outage Constraints

    CERN Document Server

    Li, Wei-Chiang; Lin, Che; Chi, Chong-Yung

    2011-01-01

    This paper studies the coordinated beamforming design problem for the multiple-input single-output (MISO) interference channel, assuming only channel distribution information (CDI) at the transmitters. For a given requirement on the rate outage probability for receivers, we aim to maximize the system utility (e.g., the weighted sum rate, weighted proportional fairness rate, and the weighed harmonic mean rate) subject to the rate outage constraints and individual power constraints. The outage constraints, however, lead to a complicated, nonconvex structure for the considered beamforming design problem and make the optimization problem difficult to handle. While this nonconvex optimization problem can be solved in an exhaustive search manner, this brute-force approach is only feasible when the number of transmitter-receiver pairs is small. For a system with a large number of transmitter-receiver pairs, computationally efficient alternatives are necessary. The focus of this paper is hence on the design of such e...

  19. Outage performance of reactive cooperation in Nakagami-m fading channels

    KAUST Repository

    Benjillali, Mustapha

    2010-06-01

    In this paper, we investigate the outage performance of Decode-and-Forward with reactive relaying in dual-hop cooperetive Nakagaml-m fading links. The destination, based on the umque knowledge of local second hop channel state information, selects the best relay to increase the chances of cooperation when the direct link is also available. After deriving the exact distribution of the variables of interest, the outage probability of the system - with and without the direct link - is obtained in closed-form, and the ε-outage capacity is derived in the particular c.se wh.ere the channel model is reduced to a Rayleigh fading. Simulation results confirm the accuracy of our analysis for a large selection of system and fading parameters.

  20. A Simple Scheme for Improved Performance of Fixed Outage Rate Cellular System

    Directory of Open Access Journals (Sweden)

    Hussein M.A. Basi

    2004-01-01

    Full Text Available The traffic characteristic of mobile cellular systems is rather distinct from that of a fixed telephone network. However the system planning and design are still carried out with the tools of conventional traffic theory. In the recent days much work is being done in the performance evaluation of mobile or cellular communication systems in order to develop a system with greater efficiency. The useful parameters to estimate the performance of the system are voice quality, frequency spectrum efficiency and Grade of Service (GOS. The grade of service will be affected due to outage of channels. In this study, a new scheme is proposed to reduce lost calls due to channel outage in the fixed rate outage cellular system. In this proposed scheme the call will never dropped but may be delayed. The system performance is evaluated for different conditions and the results are discussed.

  1. Cost Benefit Analysis of the Power Storage System Considering Outage Cost in the Deregulated Power Market

    Science.gov (United States)

    Tsuru, Hirokazu; Fujii, Yasumasa

    In this paper, the authors propose the mathematical model which derives the optimal operation strategies of an on-site power storage system through the use of stochastic dynamic programming technique. The model takes account of the variations and uncertainties of electricity market prices as well as the outage costs of power grid failures. The market price fluctuation is modeled with stochastic differential equation. The stochastic state transitions between normal and failed systems are modeled with exponential density functions. The derived optimal operation indicates that the economic value of the storage system may be increased substantially, if the avoided outage costs are explicitly taken into account. The results of the sensitivity analysis indicate that the most influential parameters are the magnitude of outage cost and the mean time to failure of power grid.

  2. Outage Performance of Flexible OFDM Schemes in Packet-Switched Transmissions

    Directory of Open Access Journals (Sweden)

    Romain Couillet

    2009-01-01

    Full Text Available α-OFDM, a generalization of the OFDM modulation, is proposed. This new modulation enhances the outage capacity performance of bursty communications. The α-OFDM scheme is easily implementable as it only requires an additional time symbol rotation after the IDFT stage and a subsequent phase rotation of the cyclic prefix. The physical effect of the induced rotation is to slide the DFT window over the frequency spectrum. When successively used with different angles α at the symbol rate, α-OFDM provides frequency diversity in block fading channels. Interestingly, simulation results show a substantial gain in terms of outage capacity and outage BER in comparison with classical OFDM modulation schemes. The framework is extended to multiantenna and multicellular OFDM-based standards. Practical simulations, in the context of 3GPP-LTE, called hereafter α-LTE, sustain our theoretical claims.

  3. Outage performance of Decode-and-Forward partial selection in Nakagami-m fading channels

    KAUST Repository

    Benjillali, Mustapha

    2010-01-01

    In this paper, we investigate the outage performance of Decode-and-Forward with partial selection relaying in dualhop cooperative Nakagami-m fading links. The source, based on the unique knowledge of local first hop channel state information, selects the best relay to increase the chances of successful decoding and hence the possibility of cooperation when the direct link is also available. After deriving the exact distribution of the sum of two gamma variates with the same shape parameter, the outage probability of the system-with and without the direct link-is obtained in closed-form. We also derive the ε-outage capacity in different particular cases, and the obtained results- when the channel model is reduced to a Rayleigh fading-are either new or correspond to those previously obtained in other works. Simulation results confirm the accuracy of our analysis for a large selection of system and fading parameters. © 2009 IEEE.

  4. Outage Performance of Decode-and-Forward in Two-Way Relaying with Outdated CSI

    KAUST Repository

    Hyadi, Amal

    2015-01-07

    In this paper, we analyze the outage behavior of decode-and-forward relaying in the context of selective two-way cooperative systems. First, a new relay selection metric is proposed to take into consideration both transmission rates and instantaneous link conditions between cooperating nodes. Afterwards, the outage probability of the proposed system is derived for Nakagami-m fading channels in the case when perfect channel state information is available and then extended to the more realistic scenario where the available channel state information (CSI) is outdated due to fast fading. New expressions for the outage probability are obtained, and the impact of imperfect CSI on the performance is evaluated. Illustrative numerical results, Monte Carlo simulations, and comparisons with similar approaches are presented to assess the accuracy of our analytical derivations and confirm the performance gain of the proposed scheme.

  5. The detection, prevention and mitigation of cascading outages in the power system

    Science.gov (United States)

    Song, Hongbiao

    This dissertation studies the causes and mechanism of power system cascading outages and develops new methods and new tools to help detect, prevent and mitigate the outages. Three effective solutions: a steady state control scheme, a transient stability control scheme, and an interactive system-wide and local scheme have been proposed using those new methods and tools. A steady state control scheme can help detect and prevent the possible cascading outage at its initial slow steady state progress stage. It uses new methods and new tools to solve the line overload, congestion or bus high/low voltage problems. New methods, such as vulnerability index (VI), margin index (MI), network contribution factor (NCF), topology processing and selected minimum load shedding (SMLS), and new tools, such as transmission network control based on a network contribution factor (NCF) method, generator control based on a generator distribution factor (GDF) method, and load control based on a load distribution factor (LDF) method have been proposed and developed. A transient stability control scheme can help prevent and mitigate the possible cascading outage at its transient progress stage if there is enough time to take action. It uses one Lyapunov direct method, potential energy boundary surface (PEBS) method, and sensitivity analysis of transient energy margin for fast stabilizing control. The results are verified by the accurate time-domain transient stability analysis method. The interactive scheme takes advantage of accurate system-wide and local information and analysis results, uses some techniques from both steady state control and transient stability control, works at both the system-wide level and local substation level, monitors the system all the time, and takes actions when needed to help detect, prevent and mitigate the possible cascading outage. Comprehensive simulation studies have been implemented using the IEEE 14-bus, 24-bus, 39-bus and 118-bus systems and promising

  6. The influence of the placement method of fuel dispenserson the refueling cycle of vehicles

    Directory of Open Access Journals (Sweden)

    Levin Ruslan Yur’evich

    2015-05-01

    Full Text Available Logistics of production processes at a gas station is a critical point in the system of petroleum products, on the operation of which the effectiveness and sustainability of the transport sector depends. The provision and supply of road transportation of petroleum products is one of the most urgent tasks.Technological processes of reception, storage of fuel and refuelling of motor vehicles on petrol stations needs a scientific study of their structure and organization. At the design stage of a gas station, it is necessary to consider quite a lot of different factors: the configuration of the area under the gas station, the scheme of arrangement and the number of fuel dispensers, the trajectory of motion and the design of vehicles, calls to the station, distance between cars on duty, between the elements of buildings and equipment, as well as the requirements for fire, building, public, sanitary-epidemiological and state regulations. Therefore, the designer has a great opportunity for varying the parameters of the elements of the station, especially when considering the characteristics of the fueled vehicles.Typical projects at a same power station include various sizes, the seizure of land to build a station changes from planning decisions and the locations of all its technological elements. For increase of functioning efficiency of transportation systems of petroleum products in modern conditions on the basis of the design and technical innovations it is necessary to conduct special studies.Research planning decisions for a refueling station led to the conclusion that the placement of technological equipment in the refueling area has a certain impact on the length of vehicles service. Improving the layout of the refueling zone several times reduces the loss of the components of the refueling cycle time and increase the capacity of the station.Information base describing the stages of a gas station includes parts of refueling cycle time and

  7. ANALYSIS OF FEEDERS OUTAGES ON THE DISTRIBUTION SYSTEM OF ZARIA TOWN

    OpenAIRE

    Adegboye, B A

    2010-01-01

    The paper is aimed at analysing the outages on the feeders of the distribution system, in Zaria Town, Kaduna State, Nigeria. The 11 kV feeders are the NNPC feeder, Gaskiya feeder, Sabon Gari feeder, NTC/RLY feeder and the Canteen feeder. The 33 kV feeders, on the other hand, are the Shika feeder, Giwa/Makarfi feeder and the Soba feeder. The analysis is based on the daily outage data collected for a period of about one year (April, 2003 to April, 2004 – thirteen months). From these data, the t...

  8. On the Impact of Mobility on Outage Probability in Cellular Networks

    OpenAIRE

    Kélif, Jean-Marc; Coupechoux, Marceau

    2009-01-01

    International audience; In this paper, we develop an analytical study of the mobility in cellular networks and its impact on quality of service and outage probability. We first express analytically the downlink other-cell interference factor f by using a fluid model network. It is defined here as the ratio of outer cell received power to the inner cell received power. It allows us to analyze users mobility and to derive expressions of the outage probability. We show that mobility can modify t...

  9. Outage probability analysis of wireless sensor networks in the presence of channel fading and spatial correlation

    KAUST Repository

    Al-Murad, Tamim M.

    2011-07-01

    Evaluating the reliability of wireless sensor networks is becoming more important as theses networks are being used in crucial applications. The outage probability defined as the probability that the error in the system exceeds a maximum acceptable threshold has recently been used as a measure of the reliability of such systems. In this work we find the outage probability of wireless sensor network in different scenarios of distributed sensing where sensors\\' readings are affected by spatial correlation and in the presence of channel fading. © 2011 IEEE.

  10. Reverse Link Outage Probabilities of Multicarrier CDMA Systems with Beamforming in the Presence of Carrier Frequency Offset

    Directory of Open Access Journals (Sweden)

    Xiaoyu Hu

    2007-11-01

    Full Text Available The outage probability of reverse link multicarrier (MC code-division multiple access (CDMA systems with beamforming in the presence of carrier frequency offset (CFO is studied. A conventional uniform linear array (ULA beamformer is utilized. An independent Nakagami fading channel is assumed for each subcarrier of all users. The outage probability is first investigated under a scenario where perfect beamforming is assumed. A closed form expression of the outage probability is derived. The impact of different types of beamforming impairments on the outage probability is then evaluated, including direction-of-arrival (DOA estimation errors, angle spreads, and mutual couplings. Numerical results show that the outage probability improves significantly as the number of antenna elements increases. The effect of CFO on the outage probability is reduced significantly when the beamforming technique is employed. Also, it is seen that small beamforming impairments (DOA estimation errors and angle spreads only affect the outage probability very slightly, and the mutual coupling between adjacent antenna elements does not affect the outage probability noticeably.

  11. Reverse Link Outage Probabilities of Multicarrier CDMA Systems with Beamforming in the Presence of Carrier Frequency Offset

    Directory of Open Access Journals (Sweden)

    Hu Xiaoyu

    2008-01-01

    Full Text Available The outage probability of reverse link multicarrier (MC code-division multiple access (CDMA systems with beamforming in the presence of carrier frequency offset (CFO is studied. A conventional uniform linear array (ULA beamformer is utilized. An independent Nakagami fading channel is assumed for each subcarrier of all users. The outage probability is first investigated under a scenario where perfect beamforming is assumed. A closed form expression of the outage probability is derived. The impact of different types of beamforming impairments on the outage probability is then evaluated, including direction-of-arrival (DOA estimation errors, angle spreads, and mutual couplings. Numerical results show that the outage probability improves significantly as the number of antenna elements increases. The effect of CFO on the outage probability is reduced significantly when the beamforming technique is employed. Also, it is seen that small beamforming impairments (DOA estimation errors and angle spreads only affect the outage probability very slightly, and the mutual coupling between adjacent antenna elements does not affect the outage probability noticeably.

  12. 10 CFR 501.191 - Use of natural gas or petroleum for certain unanticipated equipment outages and emergencies...

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Use of natural gas or petroleum for certain unanticipated... Natural Gas or Petroleum for Emergency and Unanticipated Equipment Outage Purposes § 501.191 Use of natural gas or petroleum for certain unanticipated equipment outages and emergencies defined in...

  13. The cost of power outages in the business and public sectors in Israel: Revealed preference vs. subjective evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Beenstock, M.; Goldin, E.; Haitovsky, Y. [Hebrew Univ. of Jerusalem, Mount Scopus (Israel)

    1997-05-01

    The economic cost of power outages is a central parameter in the cost-benefit analysis of electric power reliability and the design of electric power systems. The authors present a new methodology for estimating the cost of power outages in the business and public sections and illustrate with data for Israel. The methodology is based on the principle of revealed preference, the cost of an outage may be inferred from the actions taken by consumers to mitigate losses induced by unsupplied electricity. If outages impose costs on businesses, managers are likely to invest in back-up power to mitigate the losses that are incurred when electricity is not supplied. Investment in back-up generators may then be used to impute the mitigated and unmitigated damage from outages. 12 refs., 3 figs., 7 tabs.

  14. Refueling Stop Activity Detection and Gas Station Extraction Using Crowdsourcing Vehicle Trajectory Data

    Directory of Open Access Journals (Sweden)

    YANG Wei

    2017-07-01

    Full Text Available In view of the deficiencies of current surveying methods of gas station, an approach is proposed to extract gas station from vehicle traces. Firstly, the spatial-temporal characteristics of individual and collective refueling behavior of trajectory is analyzed from aspects of movement features and geometric patterns. Secondly, based on Stop/Move model, the velocity sequence linear clustering algorithm is proposed to extract refueling stop tracks. Finally, using the methods including Delaunay triangulation, Fourier shape recognition and semantic constraints to identify and extract gas station. An experiment using 7 days taxi GPS traces in Beijing verified the novel method. The experimental results of 482 gas stations are extracted and the correct rate achieves to 93.1%.

  15. Qualitative Risk Assessment for an LNG Refueling Station and Review of Relevant Safety Issues

    Energy Technology Data Exchange (ETDEWEB)

    Siu, N.; Herring, J.S.; Cadwallader, L.; Reece, W.; Byers, J.

    1998-02-01

    This report is a qualitative assessment of the public and worker risk involved with the operation of a liquefied natural gas (LNG) vehicle refueling facility. This study includes facility maintenance and operations, tank truck deliveries, and end-use vehicle fueling; it does not treat the risks of LNG vehicles on roadways. Accident initiating events are identified by using a Master Logic Diagram, a Failure Modes and Effects Analysis, and historical operating experiences. The event trees were drawn to depict possible sequences of mitigating events following the initiating events. The phenomenology of LNG and other vehicle fuels is discussed to characterize the hazard posed by LNG usage. Based on the risk modeling and analysis, recommendations are given to improve the safety of LNG refueling stations in the areas of procedures and training, station design, and the dissemination of ``best practice`` information throughout the LNG community.

  16. Drogue detection for autonomous aerial refueling based on convolutional neural networks

    Directory of Open Access Journals (Sweden)

    Xufeng Wang

    2017-02-01

    Full Text Available Drogue detection is a fundamental issue during the close docking phase of autonomous aerial refueling (AAR. To cope with this issue, a novel and effective method based on deep learning with convolutional neural networks (CNNs is proposed. In order to ensure its robustness and wide application, a deep learning dataset of images was prepared by utilizing real data of “Probe and Drogue” aerial refueling, which contains diverse drogues in various environmental conditions without artificial features placed on the drogues. By employing deep learning ideas and graphics processing units (GPUs, a model for drogue detection using a Caffe deep learning framework with CNNs was designed to ensure the method’s accuracy and real-time performance. Experiments were conducted to demonstrate the effectiveness of the proposed method, and results based on real AAR data compare its performance to other methods, validating the accuracy, speed, and robustness of its drogue detection ability.

  17. Interim qualitative risk assessment for an LNG refueling station and review of relevant safety issues

    Energy Technology Data Exchange (ETDEWEB)

    Siu, N.; Herring, S.; Cadwallader, L.; Reece, W.; Byers, J.

    1997-07-01

    This report is a qualitative assessment of the public and worker risk involved with the operation of a liquefied natural (LNG) vehicle refueling facility. This study includes facility maintenance and operations, tanker truck delivers and end-use vehicle fueling; it does not treat the risks of LNG vehicles on roadways. Accident initiating events are identified by using a Master Logic Diagram, a Failure Modes and Effects analysis and historical operating experiences. The event trees were drawn to depict possible sequences of mitigating events following the initiating events. The phenomenology of LNG and other vehicle fuels is discussed to characterize the hazard posed by LNG usage. Based on the risk modeling and analysis, recommendations are given to improve the safety of LNG refueling stations in the areas of procedures and training, station design, and the dissemination of best practice information throughout the LNG community.

  18. Optimal mission planning of GEO on-orbit refueling in mixed strategy

    Science.gov (United States)

    Chen, Xiao-qian; Yu, Jing

    2017-04-01

    The mission planning of GEO on-orbit refueling (OOR) in Mixed strategy is studied in this paper. Specifically, one SSc will be launched to an orbital slot near the depot when multiple GEO satellites are reaching their end of lives. The SSc replenishes fuel from the depot and then extends the lifespan of the target satellites via refueling. In the mixed scenario, only some of the target satellites could be served by the SSc, and the remaining ones will be fueled by Pseudo SScs (the target satellite which has already been refueled by the SSc and now has sufficient fuel for its operation as well as the fuel to refuel other target satellites is called Pseudo SSc here). The mission sequences and fuel mass of the SSc and Pseudo SScs, the dry mass of the SSc are used as design variables, whereas the economic benefit of the whole mission is used as design objective. The economic cost and benefit models are stated first, and then a mathematical optimization model is proposed. A comprehensive solution method involving enumeration, particle swarm optimization and modification is developed. Numerical examples are carried out to demonstrate the effectiveness of the model and solution method. Economic efficiencies of different OOR strategies are compared and discussed. The mixed strategy would perform better than the other strategies only when the target satellites satisfy some conditions. This paper presents an available mixed strategy scheme for users and analyzes its advantages and disadvantages by comparing with some other OOR strategies, providing helpful references to decision makers. The best strategy in practical applications depends on the specific demands and user preference.

  19. Evaluation of the Production CH-47D Adverse Weather Cockpit (AWC) Aerial Refueling System

    Science.gov (United States)

    1988-09-01

    aircraft longitudinal axis at a preset elevation. The system also has an automatic tracking feature which enables the optics to automatically track an...I degrees left of the aircraft longitudinal axis. Approximately 25 percent of the screen is obtcured when looking 90 degrees right of the aircraft ... aircraft longitudinal axis before the tip of the refueling probe is visible on the right side of the screen, When looking 90 degrees right of the aircraft

  20. Refueling Behavior of Flexible Fuel Vehicle Drivers in the Federal Fleet

    Energy Technology Data Exchange (ETDEWEB)

    Daley, R.; Nangle, J.; Boeckman, G.; Miller, M.

    2014-05-01

    Federal fleets are a frequent subject of legislative and executive efforts to lead a national transition to alternative fuels and advanced vehicle technologies. Section 701 of the Energy Policy Act of 2005 requires that all dual-fueled alternative fuel vehicles in the federal fleet be operated on alternative fuel 100% of the time when they have access to it. However, in Fiscal Year (FY) 2012, drivers of federal flex fuel vehicles (FFV) leased through the General Services Administration refueled with E85 24% of the time when it was available--falling well short of the mandate. The U.S. Department of Energy's National Renewable Energy Laboratory completed a 2-year Laboratory Directed Research and Development project to identify the factors that influence the refueling behavior of federal FFV drivers. The project began with two primary hypotheses. First, information scarcity increases the tendency to miss opportunities to purchase E85. Second, even with perfect information, there are limits to how far drivers will go out of their way to purchase E85. This paper discusses the results of the project, which included a June 2012 survey of federal fleet drivers and an empirical analysis of actual refueling behavior from FY 2009 to 2012. This research will aid in the design and implementation of intervention programs aimed at increasing alternative fuel use and reducing petroleum consumption.

  1. Operational Readiness Verification, Phase 3. A Field Study at a Swedish NPP during a Productive Outage (Safety-train Outage)

    Energy Technology Data Exchange (ETDEWEB)

    Hollnagel, Erik [Linkoeping Univ. (Sweden). Dept. of Computer and Information Science; Gauthereau, Vincent; Persson, Bodil [Linkoeping Univ. (Sweden). Dept. of Industrial Engineering

    2004-01-01

    This report describes the results from Phase III of a study on Operational Readiness Verification (ORV) that was carried out from December 2002 to November 2003. The work comprised a field study of ORV activities at a Swedish NPP during a planned productive outage, which allowed empirical work to be conducted in an appropriate environment with good accessibility to technical staff. One conclusion from Phase I of this project was the need to look more closely at the differences between three levels or types of tests that occur in ORV: object (component) test, system level test and (safety) function test, and to analyse the different steps of testing in order to understand the nontrivial relations between tests and safety. A second conclusion was the need to take a closer look at the organisation's ability to improvise in the sense of adjusting pre-defined plans to the actual conditions under which they are to be carried out. Phase II of the project found that although all three types of test occurred, they were rather used according to need rather than to a predefined arrangement or procedure. The complexity of ORV could be understood and described by using the concepts of Community of Practice, embedding, and Efficiency-Thoroughness Trade-Off. In addition, organisation and the different communities of practice improvise by adjusting pre-defined plans or work orders to the existing conditions. Such improvisations take place both on the levels of individual actions, on the level of communities of practice, and on the organisational level. The ability to improvise is practically a necessity for work to be carried out, but is also a potential risk. Phase III of the project studied how tasks are adapted relative to the different types of embedding and the degree of correspondence between nominal and actual ORV. It also looked further at the different Communities of Practice that are part of maintenance and ORV, focusing on the coordination and communication between

  2. The effect of power outages on in-facility mortality in healthcare facilities: Evidence from Ghana.

    Science.gov (United States)

    Apenteng, Bettye A; Opoku, Samuel T; Ansong, Daniel; Akowuah, Emmanuel A; Afriyie-Gyawu, Evans

    2016-08-17

    The World Bank estimates that at least 25 countries in the Sub-Saharan region of Africa experience chronic power outages. However, the implications of power shortages are often discussed within the context of industrial and economic disruptions, with little attention given to the health impact. Using a nationally representative data of healthcare facilities from the 2012 Ghana Access, Bottlenecks, Cost and Equity (ABCE) Health Facility Survey, this study aims to assess the impact of power outages on in-healthcare facility mortality in Ghana, a country that has experienced worsening energy crises in the last few decades. Findings revealed a positive association between the frequency of power outages and in-facility mortality, with the risk for mortality estimated to increase by 43% for each day the power was out for over 2 h. Further, when compared to an urban healthcare facility experiencing the same frequency of power outages, the risk of mortality was found to be lower in the rural facility. These findings call for a concerted effort among all stakeholders to ensure the availability of consistent power supply in healthcare facilities, in order to provide the necessary environment for the successful provision of healthcare for the citizens of Ghana.

  3. Impact of industry strategies and consumer attitude on growth of the hydrogen vehicle fleet and corresponding refuelling infrastructure

    Energy Technology Data Exchange (ETDEWEB)

    Lebutsch, Paul; Weeda, Marcel; Ajah, Augustine N.; Meerwaldt, Harold [ECN - Energy Research Centre of the Netherlands (Netherlands)

    2010-07-01

    Hydrogen is touted as a major energy carrier for future transport. For this to be actualized, the parallel roll-out and growth of both the H{sub 2} vehicle market and hydrogen refuelling infrastructure must be guaranteed. Within the Dutch THRIVE project (Towards a Hydrogen Refuelling Infrastructure for VEhicles) a generic customer-oriented tool is being developed to project the growth of the hydrogen vehicle fleet and the development of a corresponding refuelling infrastructure in both temporal and spatial domains. A multi-parametric sensitivity analysis is carried out to determine the associated impacts of different input assumptions covering industry strategies (fuel suppliers and car manufacturers) and the consumer attitude towards fuel availability. The strategies of fuel suppliers are simulated by assuming, amongst other parameters, different initial refuelling networks and required refuelling unit utilisation, which dictates the growth of the refuelling infrastructure. Strategies of car manufactures are simulated by varying the rate of introducing new hydrogen car models into the market. The consumer attitude towards the availability of hydrogen is based on a survey performed within the THRIVE project that reflects current refuelling behaviour of motorists. Local and global fuel availability is calculated based on the drive time between zip codes and the effect of a change in consumer attitude is shown. Besides analysing the effect of every parameter on its own, the model has proven to generate trustworthy results by varying assumptions on strategies and behaviour in a consistent way, indicative for ''business-as-usual'' up to ''high ambition level'' scenarios. Hydrogen car penetration from less than 10% to more than 60% of the total passenger car fleet are projected for 2050, depending for instance on a change in consumers' attitude, size of the initial network and whether or not hydrogen cars are also introduced

  4. Outage probability of a relay strategy allowing intra-link errors utilizing Slepian-Wolf theorem

    Science.gov (United States)

    Cheng, Meng; Anwar, Khoirul; Matsumoto, Tad

    2013-12-01

    In conventional decode-and-forward (DF) one-way relay systems, a data block received at the relay node is discarded, if the information part is found to have errors after decoding. Such errors are referred to as intra-link errors in this article. However, in a setup where the relay forwards data blocks despite possible intra-link errors, the two data blocks, one from the source node and the other from the relay node, are highly correlated because they were transmitted from the same source. In this article, we focus on the outage probability analysis of such a relay transmission system, where source-destination and relay-destination links, Link 1 and Link 2, respectively, are assumed to suffer from the correlated fading variation due to block Rayleigh fading. The intra-link is assumed to be represented by a simple bit-flipping model, where some of the information bits recovered at the relay node are the flipped version of their corresponding original information bits at the source. The correlated bit streams are encoded separately by the source and relay nodes, and transmitted block-by-block to a common destination using different time slots, where the information sequence transmitted over Link 2 may be a noise-corrupted interleaved version of the original sequence. The joint decoding takes place at the destination by exploiting the correlation knowledge of the intra-link (source-relay link). It is shown that the outage probability of the proposed transmission technique can be expressed by a set of double integrals over the admissible rate range, given by the Slepian-Wolf theorem, with respect to the probability density function ( pdf) of the instantaneous signal-to-noise power ratios (SNR) of Link 1 and Link 2. It is found that, with the Slepian-Wolf relay technique, so far as the correlation ρ of the complex fading variation is | ρ|outage curve converges to 1 when the bit streams are not fully correlated. Moreover, the Slepian-Wolf outage probability is proved

  5. Outage Analysis of Ultra-Wideband System in Lognormal Multipath Fading and Square-Shaped Cellular Configurations

    Directory of Open Access Journals (Sweden)

    Pirinen Pekka

    2006-01-01

    Full Text Available Generic ultra-wideband (UWB spread-spectrum system performance is evaluated in centralized and distributed spatial topologies comprising square-shaped indoor cells. Statistical distributions for link distances in single-cell and multicell configurations are derived. Cochannel-interference-induced outage probability is used as a performance measure. The probability of outage varies depending on the spatial distribution statistics of users (link distances, propagation characteristics, user activities, and receiver settings. Lognormal fading in each channel path is incorporated in the model, where power sums of multiple lognormal signal components are approximated by a Fenton-Wilkinson approach. Outage performance of different spatial configurations is outlined numerically. Numerical results show the strong dependence of outage probability on the link distance distributions, number of rake fingers, and path losses.

  6. Outage Probability of Interference-limited Switch and Stay Diversity System over Gamma Shadowed Nakagami-m Fading Channels

    Science.gov (United States)

    Djordjevic, Goran T.; Antic, Dragan

    2013-12-01

    In this paper, the outage performance of a dual-branch switch and stay combining (SSC) diversity receiver operating over composite multipath Nakagami-m fading/gamma shadowing channels in the presence of a co-channel interference is determined. For a single channel composite fading environment, we derive the new analytical expressions for the probability density function and cumulative distribution function of the instantaneous signal-to-interference (SIR) ratio that can be used as alternatives to the previously published results. In the case of non-identically distributed and power unbalanced SSC branches with arbitrary fading parameters, the outage performance is determined. The choice of optimal switching threshold in minimum outage probability sense is discussed. The results show the outage probability dependence on simultaneous effects of the SIR unbalancing, as well as multipath fading and shadowing severities. The analytical results are confirmed by Monte Carlo simulations.

  7. Cognitive multiple-antenna network in outage-restricted primary system

    DEFF Research Database (Denmark)

    Maham, Behrouz; Popovski, Petar

    2013-01-01

    In the commons model for the spectrum sharing, cognitive users can access the spectrum as long as the target performance in the legitimate primary system is not violated. In this paper, we consider a downlink primary multiple-input-single-output (MISO) system which operates under a controlled...... interference from the downlink MISO cognitive radio, also called secondary system. We derive exact expressions for outage probability of the primary user under Rayleigh fading, when the primary system is exposed to interference from a secondary base station. Moreover, in high-SNR scenario, a closed...... there is an outage constraint at the primary system, and a simple solution is proposed. Finally, the analytical results are confirmed by simulations, in which we analyze the impact of different parameters, such as the number of antennas and the amount of the interference on the system performance; these could...

  8. A RLS-SVM Aided Fusion Methodology for INS during GPS Outages

    Science.gov (United States)

    Yao, Yiqing; Xu, Xiaosu

    2017-01-01

    In order to maintain a relatively high accuracy of navigation performance during global positioning system (GPS) outages, a novel robust least squares support vector machine (LS-SVM)-aided fusion methodology is explored to provide the pseudo-GPS position information for the inertial navigation system (INS). The relationship between the yaw, specific force, velocity, and the position increment is modeled. Rather than share the same weight in the traditional LS-SVM, the proposed algorithm allocates various weights for different data, which makes the system immune to the outliers. Field test data was collected to evaluate the proposed algorithm. The comparison results indicate that the proposed algorithm can effectively provide position corrections for standalone INS during the 300 s GPS outage, which outperforms the traditional LS-SVM method. Historical information is also involved to better represent the vehicle dynamics. PMID:28245549

  9. On the Outage Performance of Full-Duplex Selective Decode-and-Forward Relaying

    KAUST Repository

    Khafagy, Mohammad Galal

    2013-02-25

    We evaluate the outage performance in a three-terminal full-duplex relay channel that adopts a selective decode-and-forward protocol, taking relay self-interference into account. Previous work focused on coverage extension scenarios where direct source-destination transmissions are neglected or considered as interference. In this work, we account for the relay self-interference, and exploit the cooperative diversity offered by the independently fading source/relay message replicas that arrive at the destination. We present an approximate, yet accurate, closed-form expression for the end-to-end outage probability that captures their joint effect. With the derived expression in hand, we propose a relay transmit power optimization scheme that only requires the relay knowledge of channel statistics. Finally, we corroborate our analysis with simulations.

  10. Method for estimating power outages and restoration during natural and man-made events

    Energy Technology Data Exchange (ETDEWEB)

    Omitaomu, Olufemi A.; Fernandez, Steven J.

    2016-01-05

    A method of modeling electric supply and demand with a data processor in combination with a recordable medium, and for estimating spatial distribution of electric power outages and affected populations. A geographic area is divided into cells to form a matrix. Within the matrix, supply cells are identified as containing electric substations and demand cells are identified as including electricity customers. Demand cells of the matrix are associated with the supply cells as a function of the capacity of each of the supply cells and the proximity and/or electricity demand of each of the demand cells. The method includes estimating a power outage by applying disaster event prediction information to the matrix, and estimating power restoration using the supply and demand cell information of the matrix and standardized and historical restoration information.

  11. Cognitive Multiple Access Network with Outage Margin in the Primary System

    CERN Document Server

    Maham, Behrouz; Zhou, Xiangyun; Hjørungnes, Are

    2011-01-01

    This paper investigates the problem of spectrally efficient operation of a multiuser uplink cognitive radio system in the presence of a single primary link. The secondary system applies opportunistic interference cancelation (OIC) and decode the primary signal when such an opportunity is created. We derive the achievable rate in the secondary system when OIC is used. This scheme has a practical significance, since it enables rate adaptation without requiring any action from the primary system. The \\emph{exact} expressions for outage probability of the primary user are derived, when the primary system is exposed to interference from secondary users. Moreover, approximated formulas and tight lower and upper bounds for the ergodic sum-rate capacity of the secondary network are found. Next, the power allocation is investigated in the secondary system for maximizing the sum-rate under an outage constraint at the primary system. We formulate the power optimization problem in various scenarios depending on the avail...

  12. Recent performance of and plasma outage studies with the SNS H- source

    Science.gov (United States)

    Stockli, M. P.; Han, B.; Murray, S. N.; Pennisi, T. R.; Piller, C.; Santana, M.; Welton, R.

    2016-02-01

    Spallation Neutron Source ramps to higher power levels that can be sustained with high availability. The goal is 1.4 MW despite a compromised radio frequency quadrupole (RFQ), which requires higher radio frequency power than design levels to approach the nominal beam transmission. Unfortunately at higher power the RFQ often loses its thermal stability, a problem apparently enhanced by beam losses and high influxes of hydrogen. Delivering as much H- beam as possible with the least amount of hydrogen led to plasma outages. The root cause is the dense 1-ms long ˜55-kW 2-MHz plasma pulses reflecting ˜90% of the continuous ˜300 W, 13-MHz power, which was mitigated with a 4-ms filter for the reflected power signal and an outage resistant, slightly detuned 13-MHz match. Lowering the H2 gas also increased the H- beam current to ˜55 mA and increased the RFQ transmission by ˜7% (relative).

  13. Outage and Capacity Performance Evaluation of Distributed MIMO Systems over a Composite Fading Channel

    Directory of Open Access Journals (Sweden)

    Wenjie Peng

    2014-01-01

    Full Text Available The exact closed-form expressions regarding the outage probability and capacity of distributed MIMO (DMIMO systems over a composite fading channel are derived. This is achieved firstly by using a lognormal approximation to a gamma-lognormal distribution when a mobile station (MS in the cell is in a fixed position, and the so-called maximum ratio transmission/selected combining (MRT-SC and selected transmission/maximum ratio combining (ST-MRC schemes are adopted in uplink and downlink, respectively. Then, based on a newly proposed nonuniform MS cell distribution model, which is more consistent with the MS cell hotspot distribution in an actual communication environment, the average outage probability and capacity formulas are further derived. Finally, the accuracy of the approximation method and the rationality of the corresponding theoretical analysis regarding the system performance are proven and illustrated by computer simulations.

  14. A RLS-SVM Aided Fusion Methodology for INS during GPS Outages.

    Science.gov (United States)

    Yao, Yiqing; Xu, Xiaosu

    2017-02-24

    In order to maintain a relatively high accuracy of navigation performance during global positioning system (GPS) outages, a novel robust least squares support vector machine (LS-SVM)-aided fusion methodology is explored to provide the pseudo-GPS position information for the inertial navigation system (INS). The relationship between the yaw, specific force, velocity, and the position increment is modeled. Rather than share the same weight in the traditional LS-SVM, the proposed algorithm allocates various weights for different data, which makes the system immune to the outliers. Field test data was collected to evaluate the proposed algorithm. The comparison results indicate that the proposed algorithm can effectively provide position corrections for standalone INS during the 300 s GPS outage, which outperforms the traditional LS-SVM method. Historical information is also involved to better represent the vehicle dynamics.

  15. A RLS-SVM Aided Fusion Methodology for INS during GPS Outages

    Directory of Open Access Journals (Sweden)

    Yiqing Yao

    2017-02-01

    Full Text Available In order to maintain a relatively high accuracy of navigation performance during global positioning system (GPS outages, a novel robust least squares support vector machine (LS-SVM-aided fusion methodology is explored to provide the pseudo-GPS position information for the inertial navigation system (INS. The relationship between the yaw, specific force, velocity, and the position increment is modeled. Rather than share the same weight in the traditional LS-SVM, the proposed algorithm allocates various weights for different data, which makes the system immune to the outliers. Field test data was collected to evaluate the proposed algorithm. The comparison results indicate that the proposed algorithm can effectively provide position corrections for standalone INS during the 300 s GPS outage, which outperforms the traditional LS-SVM method. Historical information is also involved to better represent the vehicle dynamics.

  16. Prediction of power system frequency response after generator outages using neural nets

    Energy Technology Data Exchange (ETDEWEB)

    Djukanovic, M.B.; Popovic, D.P. (Electrotechnicki Inst. ' Nikola Tesla' , Belgrade (Yugoslavia)); Sobajic, D.J.; Pao, Y.-H. (Case Western Reserve Univ., Cleveland, OH (United States))

    1993-09-01

    A new methodology is presented for estimating the frequency behaviour of power systems necessary for an indication of under-frequency load shedding in steady-state security assessment. It is well known that large structural disturbances such as generator tripping or load outages can initiate cascading outages, system separation into islands, and even the complete breakup. The approach provides a fairly accurate method of estimating the system average frequency response without making simplifications or neglecting non-linearities and small time constants in the equations of generating units, voltage regulators and turbines. The efficiency of the new procedure is demonstrated using the New England power system model for a series of characteristic perturbations. The validity of the proposed approach is verified by comparison with the simulation of short-term dynamics including effects of control and automatic devices. (author)

  17. Call admission and capacity analysis for multimedia CDMA networks based on outage probability constraint

    Science.gov (United States)

    Bo, Xiaoming; Chen, Zujue

    2004-04-01

    Capacity analysis and call admission control in wireless communication systems are essential for system design and operation. The capacity for imperfectly power controlled multimedia code division multiple access (CDMA) networks based on system outage probability constraint is presented and analyzed. A handoff prioritized call admission scheme is then developed based on the derived system capacity and evaluated using the K-dimensional birth-death process model. A more general assumption that average channel holding times for new calls and handoff calls are not equal and an effective approximate model are adopted in the performance analysis. Numerical examples are given to demonstrate the system performance in terms of blocking probabilities, resource utilization and average system throughput. It is shown that the system parameters such as outage probability constraint and power control errors have great impact on system capacity and performance.

  18. Exact Outage Performance Analysis of Multiuser Multi-relay Spectrum Sharing Cognitive Networks

    Directory of Open Access Journals (Sweden)

    T. Zhang

    2015-04-01

    Full Text Available In this paper, we investigate the outage performance of dual-hop multiuser multi-relay cognitive radio networks under spectrum sharing constraints. Using an efficient relay-destination selection scheme, the exact and asymptotic closed-form expressions for the outage probability are derived. From these expressions it is indicated that the achieved diversity order is only determined by the number of secondary user (SU relays and destinations, and equals to M+N (where M and N are the number of destination nodes and relay nodes, respectively. Further, we find that the coding gain of the SU network will be affected by the interference threshold $bar I$ at the primary user (PU receiver. Specifically, as the increases of the interference threshold, the coding gain of the considered network approaches to that of the multiuser multi-relay system in the non-cognitive network. Finally, our study is corroborated by representative numerical examples.

  19. Outage Performance of Hybrid FSO/RF System with Low-Complexity Power Adaptation

    KAUST Repository

    Rakia, Tamer

    2016-02-26

    Hybrid free-space optical (FSO) / radio-frequency (RF) systems have emerged as a promising solution for high data- rate wireless communication systems. We consider truncated channel inversion based power adaptation strategy for coherent and non- coherent hybrid FSO/RF systems, employing an adaptive combining scheme. Specifically, we activate the RF link along with the FSO link when FSO link quality is unacceptable, and adaptively set RF transmission power to ensure constant combined signal-to-noise ratio at receiver terminal. Analytical expressions for the outage probability of the hybrid system with and without power adaptation are derived. Numerical examples show that, the hybrid FSO/RF systems with power adaptation achieve considerable outage performance improvement over conventional hybrid FSO/RF systems without power adaptation. © 2015 IEEE.

  20. On the outage capacity of the block fading channel at low-power regime

    KAUST Repository

    Rezki, Zouheir

    2014-06-01

    Outage performance of the M-block fading with additive white Gaussian noise (BF-AWGN) is investigated at low-power regime. We consider delay-constrained constant-rate communications with perfect channel state information (CSI) at both the transmitter and the receiver (CSI-TR), under a short-term power constraint. We show that selection diversity that allocates all the power to the strongest block is asymptotically optimal. Then, we provide a simple characterization of the outage probability in the regime of interest. We quantify the reward due to CSI-TR over the constant-rate constant-power scheme and show that this reward increases with the delay constraint. For instance, for Rayleigh fading, we find that a power gain up to 4.3 dB is achievable. © 2014 IEEE.

  1. Recent Performance of and Plasma Outage Studies with the SNS H- Source

    Energy Technology Data Exchange (ETDEWEB)

    Stockli, Martin P [ORNL; Han, Baoxi [ORNL; Murray Jr, S N [ORNL; Pennisi, Terry R [ORNL; Piller, Chip [ORNL; Santana, Manuel [ORNL; Welton, Robert F [ORNL

    2016-01-01

    SNS ramps to higher power levels that can be sustained with high availability. The goal is 1.4 MW despite a compromised RFQ, which requires higher RF power than design levels to approach the nominal beam transmission. Unfortunately at higher power the RFQ often loses its thermal stability, a problem apparently enhanced by beam losses and high influxes of hydrogen. Delivering as much H- beam as possible with the least amount of hydrogen led to plasma outages. The root cause is the dense 1-ms long ~55-kW 2-MHz plasma pulses reflecting ~90% of the continuous ~300W, 13-MHz power, which was mitigated with a 4-ms filter for the reflected power signal and an outage resistant, slightly-detuned 13-MHz match. Lowering the H2 also increased the H- beam current to ~55 mA, and increased the transmission by ~7%.

  2. Community Energy: Analysis of Hydrogen Distributed Energy Systems with Photovoltaics for Load Leveling and Vehicle Refueling

    Energy Technology Data Exchange (ETDEWEB)

    Steward, D.; Zuboy, J.

    2014-10-01

    Energy storage could complement PV electricity generation at the community level. Because PV generation is intermittent, strategies must be implemented to integrate it into the electricity system. Hydrogen and fuel cell technologies offer possible PV integration strategies, including the community-level approaches analyzed in this report: (1) using hydrogen production, storage, and reconversion to electricity to level PV generation and grid loads (reconversion scenario); (2) using hydrogen production and storage to capture peak PV generation and refuel hydrogen fuel cell electric vehicles (FCEVs) (hydrogen fueling scenario); and (3) a comparison scenario using a battery system to store electricity for EV nighttime charging (electric charging scenario).

  3. Extending the features of RBMK refuelling machine simulator with a training tool based on virtual reality

    Energy Technology Data Exchange (ETDEWEB)

    Khoudiakov, M.; Slonimsky, V.; Mitrofanov, S. (and others)

    2004-07-01

    The paper describes a continuation of efforts of an international Russian - Norwegian joint team to improve operational safety during the refuelling process of an RBMK-type reactor by implementing a training simulator based on an innovative Virtual Reality (VR) approach. During the preceding 1st stage of the project a display-based simulator was extended with VR models of the real Refuelling Machine (RM) and its environment in order to improve both the learning process and operation's effectiveness. The simulator's challenge is to support the performance (operational activity) of RM operational staff firstly by helping them to develop basic knowledge and skills as well as to keep skilled staff in close touch with the complex machinery of the Refuelling Machine. During the 2nd stage of the joint project the functional scope of the VR-simulator was greatly enhanced - firstly, by connecting to the RBMK-unit full-scope simulator, and, secondly, by including a training program and simulator model upgrade. The present 3rd stage of the Project is primarily oriented towards the improvement of the training process for maintenance and operational personnel by means of a development of the Training Support Methodology and Courses (TSMC) to be based on Virtual Reality and enlarged functionality of 3D and process modelling. The TMSC development is based on Russian and International Regulatory Bodies requirements and recommendations. Design, development and creation of a specialised VR-based Training System for RM Maintenance Personnel are very important for the Russian RBMK plants. The main goal is to create a powerful, autonomous VR-based simulator for training technical maintenance personnel on the Refuelling Machine. VR based training is expected to improve the effect of training compared to the current training based on traditional methods using printed documentation. The LNPP management and the Regulatory Bodies supported this goal. The VR-based Training System

  4. LNG汽车加气站消防安全设计%Fire protection design of LNG vehicle refueling station

    Institute of Scientific and Technical Information of China (English)

    朱世敏

    2011-01-01

    对LNG汽车加气站和CNG汽车加气站应用现状进行比照分析,LNG站将是未来城市规模化发展天然气汽车的理想途径.由于我国目前尚无LNG汽车加气站的设计规范,针对LNG汽车加气站消防安全设计进行探讨分析.%The present situation of LNG and CNG vehicle refueling station were compared and analyzed. LNG station is the ideal solution for the scale development of LNG vehicle. The fire protection design of LNG vehicle refueling station was discussed on the situation of there is no design code for LNG vehicle refueling station yet.

  5. Power Outages, Extreme Events and Health: a Systematic Review of the Literature from 2011-2012

    OpenAIRE

    Klinger, Chaamala; Landeg, Owen; Murray, Virginia

    2014-01-01

    Background Extreme events (e.g. flooding) threaten critical infrastructure including power supplies. Many interlinked systems in the modern world depend on a reliable power supply to function effectively. The health sector is no exception, but the impact of power outages on health is poorly understood. Greater understanding is essential so that adverse health impacts can be prevented and/or mitigated. Methods We searched Medline, CINAHL and Scopus for papers about the health impacts of power ...

  6. Use of VIIRS DNB Data to Monitor Power Outages and Restoration for Significant Weather Events

    Science.gov (United States)

    Jedlovec, Gary; Molthan, Andrew

    2008-01-01

    NASA fs Short-term Prediction Research and Transition (SPoRT) project operates from NASA's Marshall Space Flight Center in Huntsville, Alabama. The team provides unique satellite data to the National Weather Service (NWS) and other agencies and organizations for weather analysis. While much of its work is focused on improving short-term weather forecasting, the SPoRT team supported damage assessment and response to Hurricane Superstorm Sandy by providing imagery that highlighted regions without power. The team used data from the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite. The VIIRS low-light sensor, known as the day-night-band (DNB), can detect nighttime light from wildfires, urban and rural communities, and other human activity which emits light. It can also detect moonlight reflected from clouds and surface features. Using real time VIIRS data collected by our collaborative partner at the Space Science and Engineering Center of the University of Wisconsin, the SPoRT team created composite imagery to help detect power outages and restoration. This blackout imagery allowed emergency response teams from a variety of agencies to better plan and marshal resources for recovery efforts. The blackout product identified large-scale outages, offering a comprehensive perspective beyond a patchwork GIS mapping of outages that utility companies provide based on customer complaints. To support the relief efforts, the team provided its imagery to the USGS data portal, which the Federal Emergency Management Agency (FEMA) and other agencies used in their relief efforts. The team fs product helped FEMA, the U.S. Army Corps of Engineers, and U.S. Army monitor regions without power as part of their disaster response activities. Disaster responders used the images to identify possible outages and effectively distribute relief resources. An enhanced product is being developed and integrated into a web

  7. Time management challenges of major refurbishment projects : An analysis of 20 hydropower outages at Fortum

    OpenAIRE

    Nyqvist, Daniel

    2015-01-01

    While most western hydropower sites are already developed or protected by legislation, the aging hydropower park requires refurbishment actions. Especially to tackle the challenges of an increased fluctuation at the grid coming from the expansion of other renewable energy sources such as wind power. The company Fortum is carrying out a number of major refurbishment projects every year and want to enhance their time performance during the outage. Delayed projects are resulting in unexpected co...

  8. Final report of MoReMO 2011-2012. Modelling resilience for maintenance and outage

    Energy Technology Data Exchange (ETDEWEB)

    Gotcheva, N.; Macchi, L.; Oedewald, P. [Technical Research Centre of Finland (VTT), Espoo (Finland); Eitrheim, M.H.R. [Institute for Energy Technology (IFE) (Norway); Axelsson, C.; Reiman, T.; Pietikaeinen, E. [Ringhals AB (NPP), Vattenfall AB (Sweden)

    2013-04-15

    The project Modelling Resilience for Maintenance and Outage (MoReMO) represents a two-year joint effort by VTT Technical Research Centre of Finland, Institute for Energy Technology (IFE, Norway) and Vattenfall (Sweden) to develop and test new approaches for safety management. The overall goal of the project was to present concepts on how resilience can be operationalized and built in a safety critical and socio-technical context. Furthermore, the project also aimed at providing guidance for other organizations that strive to develop and improve their safety performance in a business driven industry. We have applied four approaches in different case studies: Organisational Core Task modelling (OCT), Functional Resonance Analysis Method (FRAM), Efficiency Thoroughness Trade-Off (ETTO) analysis, and Work Practice and Culture Characterisation. During 2011 and 2012 the MoReMO project team has collected data through field observations, interviews, workshops, and document analysis on the work practices and adjustments in maintenance and outage in Nordic NPPs. The project consisted of two sub-studies, one focused on identifying and assessing adjustments and supporting resilient work practices in maintenance activities, while the other focused on handling performance trade-offs in maintenance and outage, as follows: A. Adjustments in maintenance work in Nordic nuclear power plants (VTT and Vattenfall). B. Handling performance trade-offs - the support of adaptive capacities (IFE and Vattenfall). The historical perspective of maintenance and outage management (Chapter 1.1) was provided by Vattenfall. Together, the two sub-studies have provided valuable insights for understanding the rationale behind work practices and adjustments, their effects on resilience, promoting flexibility and balancing between flexibility and reliability. (Author)

  9. A Tight Lower Bound to the Outage Probability of Discrete-Input Block-Fading Channels

    CERN Document Server

    Nguyen, Khoa D; Rasmussen, Lars K

    2007-01-01

    In this correspondence, we propose a tight lower bound to the outage probability of discrete-input Nakagami-m block-fading channels. The approach permits an efficient method for numerical evaluation of the bound, providing an additional tool for system design. The optimal rate-diversity trade-off for the Nakagami-m block-fading channel is also derived and a tight upper bound is obtained for the optimal coding gain constant.

  10. WLAN Hot Spot services for the automotive and oil industries :a business analysis Or : "Refuel the car with petrol and information, both ways at the gas station"

    NARCIS (Netherlands)

    L-F. Pau (Louis-François); M.H.P. Oremus

    2003-01-01

    textabstractWhile you refuel for gas ,why not refuel for information or download vehicle data ? This paper analyzes in extensive detail the user segmentation by vehicle usage , service offering , and full business models from WLAN hot spot services delivered to vehicles (private, professional ,

  11. WLAN Hot Spot services for the automotive and oil industries :a business analysis Or : "Refuel the car with petrol and information, both ways at the gas station"

    NARCIS (Netherlands)

    L-F. Pau (Louis-François); M.H.P. Oremus

    2003-01-01

    textabstractWhile you refuel for gas ,why not refuel for information or download vehicle data ? This paper analyzes in extensive detail the user segmentation by vehicle usage , service offering , and full business models from WLAN hot spot services delivered to vehicles (private, professional , publ

  12. Improving the predictive accuracy of hurricane power outage forecasts using generalized additive models.

    Science.gov (United States)

    Han, Seung-Ryong; Guikema, Seth D; Quiring, Steven M

    2009-10-01

    Electric power is a critical infrastructure service after hurricanes, and rapid restoration of electric power is important in order to minimize losses in the impacted areas. However, rapid restoration of electric power after a hurricane depends on obtaining the necessary resources, primarily repair crews and materials, before the hurricane makes landfall and then appropriately deploying these resources as soon as possible after the hurricane. This, in turn, depends on having sound estimates of both the overall severity of the storm and the relative risk of power outages in different areas. Past studies have developed statistical, regression-based approaches for estimating the number of power outages in advance of an approaching hurricane. However, these approaches have either not been applicable for future events or have had lower predictive accuracy than desired. This article shows that a different type of regression model, a generalized additive model (GAM), can outperform the types of models used previously. This is done by developing and validating a GAM based on power outage data during past hurricanes in the Gulf Coast region and comparing the results from this model to the previously used generalized linear models.

  13. Outage behavior of slow fading channels with power control using noisy quantized CSIT

    CERN Document Server

    Ekbatani, Siavash; Jafarkhani, Hamid

    2008-01-01

    The topic of this study is the outage behavior of multiple-antenna slow fading channels with quantized feedback and partial power control. A fixed-rate communication system is considered. It is known from the literature that with error-free feedback, the outage-optimal quantizer for power control has a circular structure. Moreover, the diversity gain of the system increases polynomially with the cardinality of the power control codebook. Here, a similar system is studied, but when the feedback link is error-prone. We prove that in the high-SNR regime, the optimal quantizer structure with noisy feedback is still circular and the optimal Voronoi regions are contiguous non-zero probability intervals. Furthermore, the optimal power control codebook resembles a channel optimized scalar quantizer (COSQ), i.e., the Voronoi regions merge with erroneous feedback information. Using a COSQ, the outage performance of the system is superior to that of a no-feedback scheme. However, asymptotic analysis shows that the diver...

  14. Outage Analysis of Cooperative Transmission with Energy Harvesting Relay: Time Switching versus Power Splitting

    Directory of Open Access Journals (Sweden)

    Guanyao Du

    2015-01-01

    Full Text Available This paper investigates the multiuser transmission network with an energy harvesting (EH cooperative relay, where a source transmits independent information to multiple destinations with the help of an energy constrained relay. The relay can harvest energy from the radio frequency (RF signals transmitted from the source, and it helps the multiuser transmission only by consuming the harvested energy. By adopting the time switching and the power splitting relay receiver architectures, we firstly propose two protocols, the time switching cooperative multiuser transmission (TSCMT protocol and the power splitting cooperative multiuser transmission (PSCMT protocol, to enable the simultaneous information processing and EH at the relay for the system. To evaluate the system performance, we theoretically analyze the system outage probability for the two proposed protocols and then derive explicit expressions for each of them, respectively. Numerical results are provided to demonstrate the accuracy of our analytical results and reveal that compared with traditional noncooperative scheme our proposed protocols are green solutions to offer reliable communication and lower system outage probability without consuming additional energy. In particular, for the same transmit power at the source, the PSCMT protocol is superior to the TSCMT protocol to obtain lower system outage probability.

  15. Partner cooperation with decode-and-forward: Closed-form outage analysis and comparison

    KAUST Repository

    Benjillali, Mustapha

    2013-01-01

    In this paper, we investigate the outage performance of "partner cooperation" based on opportunistic Decodeand- Forward with constrained partial selection and reactive relaying strategies in dual-hop cooperative Nakagami-m fading links. The source/destination, which is based on the unique knowledge of local channel state information, selects the best relay to increase the chances of cooperation in both uplink and downlink communications when the direct link is also available. After deriving new expressions for the cumulative distribution functions of the variables of interest, the outage probability of the system is obtained in closed-form. We also derive the ε-outage capacity in different particular cases, and the obtained results - when the channel model is reduced to a Rayleigh fading - either are new or correspond to those previously obtained in other works. Simulation results confirm the accuracy of our analysis for a large selection of system and fading parameters and provide a new insight into the design and optimization of cooperative configurations. © 2012 IEEE.

  16. Outages of electric power supply resulting from cable failures Boston Edison Company system

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-07-01

    Factual data are provided regarding 5 electric power supply interruptions that occurred in the Boston Metropolitan area during April to June, 1979. Common to all of these outages was the failure of an underground cable as the initiating event, followed by multiple equipment failures. There was significant variation in the voltage ratings and types of cables which failed. The investigation was unable to delineate a single specific Boston Edison design operating or maintenance practice that could be cited as the cause of the outages. After reviewing the investigative report the following actions were recommended: the development and implementation of a plan to eliminate the direct current cable network; develop a network outage restoration plan; regroup primary feeder cables wherever possible to minimize the number of circuits in manholes, and to separate feeders to high load density areas; develop a program to detect incipient cable faults; evaluate the separation of the north and south sections of Back Bay network into separate networks; and, as a minimum, install the necessary facilities to make it possible to re-energize one section without interfering with the other; and re-evaluate the cathodic protection scheme where necessary. (LCL)

  17. Outage Probability Analysis in Power-Beacon Assisted Energy Harvesting Cognitive Relay Wireless Networks

    Directory of Open Access Journals (Sweden)

    Ngoc Phuc Le

    2017-01-01

    Full Text Available We study the performance of the secondary relay system in a power-beacon (PB assisted energy harvesting cognitive relay wireless network. In our system model, a secondary source node and a relay node first harvest energy from distributed PBs. Then, the source node transmits its data to the destination node with the help of the relay node. Also, fading coefficients of the links from the PBs to the source node and relay node are assumed independent but not necessarily identically distributed (i.n.i.d Nakagami-m random variables. We derive exact expressions for the power outage probability and the channel outage probability. Based on that, we analyze the total outage probability of the secondary relay system. Asymptotic analysis is also performed, which provides insights into the system behavior. Moreover, we evaluate impacts of the primary network on the performance of the secondary network with respect to the tolerant interference threshold at the primary receiver as well as the interference introduced by the primary transmitter at the secondary source and relay nodes. Simulation results are provided to validate the analysis.

  18. Ergodic and Outage Performance of Fading Broadcast Channels with 1-Bit Feedback

    CERN Document Server

    Niu, Bo; Somekh, Oren; Haimovich, Alexander M

    2010-01-01

    In this paper, the ergodic sum-rate and outage probability of a downlink single-antenna channel with K users are analyzed in the presence of Rayleigh flat fading, where limited channel state information (CSI) feedback is assumed. Specifically, only 1-bit feedback per fading block per user is available at the base station. We first study the ergodic sum-rate of the 1-bit feedback scheme, and consider the impact of feedback delay on the system. A closed-form expression for the achievable ergodic sum-rate is presented as a function of the fading temporal correlation coefficient. It is proved that the sum-rate scales as loglogK, which is the same scaling law achieved by the optimal non-delayed full CSI feedback scheme. The sum-rate degradation due to outdated CSI is also evaluated in the asymptotic regimes of either large K or low SNR. The outage performance of the 1-bit feedback scheme for both instantaneous and outdated feedback is then investigated. Expressions for the outage probabilities are derived, along w...

  19. An Isotropic SPPP Mo del for Femto cells Networks with Outage Probability Constraints

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun; TIAN Hui

    2015-01-01

    Femtocells have been considered as a cost-eff ective solution to unload traffic from already overbur-dened macrocell networks in 4G cellular networks. The severe interference in spectrum-sharing macro and femto networks may cause User-equipment (UE) to experience outage. We derive an utmost isotropic Spatial Poisson point process (SPPP) density for Femtocell access points (FAPs) under the UEs’ outage constraints. Based on the derived isotropic SPPP density, we propose a distributed transmit probability self-regulation scheme for an FAP to adapt its transmit probability per Transmission time in-terval (TTI). The scheme adjusts the homogeneous dis-tributed FAPs in practice deployment to the proposed isotropic one. Simulation results show that the derived den-sity can fulfill the outage probability constraints of UEs while accommodating the maximum femtocells. The self-regulation scheme can adapt the femtocell transmit prob-abilities to provide reliable downlink service, for even a large number of femtocells per cell site.

  20. Outage Analysis of Mixed Underlay Cognitive RF MIMO and FSO Relaying with Interference Reduction

    KAUST Repository

    Al-Qahtani, Fawaz S.

    2017-03-22

    In this paper, we study the outage performance of multiuser mixed underlay radio frequency (RF)/multidestinations free-space optical (FSO) links. For RF links, we consider a secondary network with multiple users that can communicate with multiple destinations through a relaying node. The relay is equipped with an antenna array at the RF side, and it uses the amplify-and-forward (AF) protocol. The primary users (PUs) are equipped with multiple antennas at transmit and receive nodes. The RF link is subjected to the aggregate PUs interference effect on the secondary network. To reduce the effect of PUs interference on secondary network at the relay node, two interference cancellation (IC) schemes are adopted, which vary in terms of complexity and achieved performance. On the other hand, the multidestination FSO links can be exploited to further enhance the quality of the second hop, and their associated channel models account for pointing errors, intensity modulation/direct detection, and heterodyne detection. For the aforementioned system model, we obtain exact and asymptotic closed-form expressions for the end-to-end outage probability. To further enhance system performance, optimal power allocation between the two hops is obtained based on the derived asymptotic outage probability expressions.

  1. Status and Prospects of the Global Automotive Fuel Cell Industry and Plans for Deployment of Fuel Cell Vehicles and Hydrogen Refueling Infrastructure

    Energy Technology Data Exchange (ETDEWEB)

    Greene, David L [ORNL; Duleep, Gopal [HD Systems

    2013-06-01

    Automobile manufacturers leading the development of mass-market fuel cell vehicles (FCVs) were interviewed in Japan, Korea, Germany and the United States. There is general agreement that the performance of FCVs with respect to durability, cold start, packaging, acceleration, refueling time and range has progressed to the point where vehicles that could be brought to market in 2015 will satisfy customer expectations. However, cost and the lack of refueling infrastructure remain significant barriers. Costs have been dramatically reduced over the past decade, yet are still about twice what appears to be needed for sustainable market success. While all four countries have plans for the early deployment of hydrogen refueling infrastructure, the roles of government, industry and the public in creating a viable hydrogen refueling infrastructure remain unresolved. The existence of an adequate refueling infrastructure and supporting government policies are likely to be the critical factors that determine when and where hydrogen FCVs are brought to market.

  2. Optimization of Allowed Outage Time and Surveillance Test Intervals

    Energy Technology Data Exchange (ETDEWEB)

    Al-Dheeb, Mujahed; Kang, Sunkoo; Kim, Jonghyun [KEPCO international nuclear graduate school, Ulsan (Korea, Republic of)

    2015-10-15

    The primary purpose of surveillance testing is to assure that the components of standby safety systems will be operable when they are needed in an accident. By testing these components, failures can be detected that may have occurred since the last test or the time when the equipment was last known to be operational. The probability a system or system component performs a specified function or mission under given conditions at a prescribed time is called availability (A). Unavailability (U) as a risk measure is just the complementary probability to A(t). The increase of U means the risk is increased as well. D and T have an important impact on components, or systems, unavailability. The extension of D impacts the maintenance duration distributions for at-power operations, making them longer. This, in turn, increases the unavailability due to maintenance in the systems analysis. As for T, overly-frequent surveillances can result in high system unavailability. This is because the system may be taken out of service often due to the surveillance itself and due to the repair of test-caused failures of the component. The test-caused failures include those incurred by wear and tear of the component due to the surveillances. On the other hand, as the surveillance interval increases, the component's unavailability will grow because of increased occurrences of time-dependent random failures. In that situation, the component cannot be relied upon, and accordingly the system unavailability will increase. Thus, there should be an optimal component surveillance interval in terms of the corresponding system availability. This paper aims at finding the optimal T and D which result in minimum unavailability which in turn reduces the risk. Applying the methodology in section 2 to find the values of optimal T and D for two components, i.e., safety injection pump (SIP) and turbine driven aux feedwater pump (TDAFP). Section 4 is addressing interaction between D and T. In general

  3. Meta-RaPS Algorithm for the Aerial Refueling Scheduling Problem

    Science.gov (United States)

    Kaplan, Sezgin; Arin, Arif; Rabadi, Ghaith

    2011-01-01

    The Aerial Refueling Scheduling Problem (ARSP) can be defined as determining the refueling completion times for each fighter aircraft (job) on multiple tankers (machines). ARSP assumes that jobs have different release times and due dates, The total weighted tardiness is used to evaluate schedule's quality. Therefore, ARSP can be modeled as a parallel machine scheduling with release limes and due dates to minimize the total weighted tardiness. Since ARSP is NP-hard, it will be more appropriate to develop a pproimate or heuristic algorithm to obtain solutions in reasonable computation limes. In this paper, Meta-Raps-ATC algorithm is implemented to create high quality solutions. Meta-RaPS (Meta-heuristic for Randomized Priority Search) is a recent and promising meta heuristic that is applied by introducing randomness to a construction heuristic. The Apparent Tardiness Rule (ATC), which is a good rule for scheduling problems with tardiness objective, is used to construct initial solutions which are improved by an exchanging operation. Results are presented for generated instances.

  4. A refuelable zinc/air battery for fleet electric vehicle propulsion

    Science.gov (United States)

    Cooper, John F.; Fleming, Dennis; Hargrove, Douglas; Koopman, Ronald; Peterman, Keith

    1995-04-01

    We report the development and on-vehicle testing of an engineering prototype zinc/air battery. The battery is refueled by periodic exchange of spent electrolyte for zinc particles entrained in fresh electrolyte. The technology is intended to provide a capability for nearly continuous vehicle operation, using the fleet's home base for 10 minute refuelings and zinc recycling instead of commercial infrastructure. In the battery, the zinc fuel particles are stored in hoppers, from which they are gravity fed into individual cells and completely consumed during discharge. A six-celled (7V) engineering prototype battery was combined with a 6 V lead/acid battery to form a parallel hybrid unit, which was tested in series with the 216 V battery of an electric shuttle bus over a 75 mile circuit. The battery has an energy density of 140 Wh/kg and a mass density of 1.5 kg/L. Cost, energy efficiency, and alternative hybrid configurations are discussed.

  5. Considering the dynamic refueling behavior in locating electric vehicle charging stations

    Science.gov (United States)

    Liu, K.; Sun, X. H.

    2014-11-01

    Electric vehicles (EVs) will certainly play an important role in addressing the energy and environmental challenges at current situation. However, location problem of EV charging stations was realized as one of the key issues of EVs launching strategy. While for the case of locating EV charging stations, more influence factors and constraints need to be considered since the EVs have some special attributes. The minimum requested charging time for EVs is usually more than 30minutes, therefore the possible delay time due to waiting or looking for an available station is one of the most important influence factors. In addition, the intention to purchase and use of EVs that also affects the location of EV charging stations is distributed unevenly among regions and should be considered when modelling. Unfortunately, these kinds of time-spatial constraints were always ignored in previous models. Based on the related research of refuelling behaviours and refuelling demands, this paper developed a new concept with dual objectives of minimum waiting time and maximum service accessibility for locating EV charging stations - named as Time-Spatial Location Model (TSLM). The proposed model and the traditional flow-capturing location model are applied on an example network respectively and the results are compared. Results demonstrate that time constraint has great effects on the location of EV charging stations. The proposed model has some obvious advantages and will help energy providers to make a viable plan for the network of EV charging stations.

  6. Design for air-to-air refuelling operations; new passenger and tanker aircraft design for AAR scenarios

    NARCIS (Netherlands)

    Li, M.O.

    2014-01-01

    Air-to-air refuelling is a way to improve fuel efficiency of the overall transport system without waiting for the improvement of basic aviation technology. To take full advantage of such an operation, both passenger aircraft and tanker aircraft (which deliver required fuel to the passenger aircraft

  7. Estimating duration intervals

    NARCIS (Netherlands)

    Ph.H.B.F. Franses (Philip Hans); B.L.K. Vroomen (Björn)

    2003-01-01

    textabstractDuration intervals measure the dynamic impact of advertising on sales. More precise, the p per cent duration interval measures the time lag between the advertising impulse and the moment that p per cent of its effect has decayed. In this paper, we derive an expression for the duration

  8. GPS navigation algorithms for Autonomous Airborne Refueling of Unmanned Air Vehicles

    Science.gov (United States)

    Khanafseh, Samer Mahmoud

    Unmanned Air Vehicles (UAVs) have recently generated great interest because of their potential to perform hazardous missions without risking loss of life. If autonomous airborne refueling is possible for UAVs, mission range and endurance will be greatly enhanced. However, concerns about UAV-tanker proximity, dynamic mobility and safety demand that the relative navigation system meets stringent requirements on accuracy, integrity, and continuity. In response, this research focuses on developing high-performance GPS-based navigation architectures for Autonomous Airborne Refueling (AAR) of UAVs. The AAR mission is unique because of the potentially severe sky blockage introduced by the tanker. To address this issue, a high-fidelity dynamic sky blockage model was developed and experimentally validated. In addition, robust carrier phase differential GPS navigation algorithms were derived, including a new method for high-integrity reacquisition of carrier cycle ambiguities for recently-blocked satellites. In order to evaluate navigation performance, world-wide global availability and sensitivity covariance analyses were conducted. The new navigation algorithms were shown to be sufficient for turn-free scenarios, but improvement in performance was necessary to meet the difficult requirements for a general refueling mission with banked turns. Therefore, several innovative methods were pursued to enhance navigation performance. First, a new theoretical approach was developed to quantify the position-domain integrity risk in cycle ambiguity resolution problems. A mechanism to implement this method with partially-fixed cycle ambiguity vectors was derived, and it was used to define tight upper bounds on AAR navigation integrity risk. A second method, where a new algorithm for optimal fusion of measurements from multiple antennas was developed, was used to improve satellite coverage in poor visibility environments such as in AAR. Finally, methods for using data-link extracted

  9. Towards a standardized grasping and refuelling on-orbit servicing for geo spacecraft

    Science.gov (United States)

    Medina, Alberto; Tomassini, Angelo; Suatoni, Matteo; Avilés, Marcos; Solway, Nick; Coxhill, Ian; Paraskevas, Iosif S.; Rekleitis, Georgios; Papadopoulos, Evangelos; Krenn, Rainer; Brito, André; Sabbatinelli, Beatrice; Wollenhaupt, Birk; Vidal, Christian; Aziz, Sarmad; Visentin, Gianfranco

    2017-05-01

    Exploitation of space must benefit from the latest advances in robotics. On-orbit servicing is a clear candidate for the application of autonomous rendezvous and docking mechanisms. However, during the last three decades most of the trials took place combining extravehicular activities (EVAs) with telemanipulated robotic arms. The European Space Agency (ESA) considers that grasping and refuelling are promising near-mid-term capabilities that could be performed by servicing spacecraft. Minimal add-ons on spacecraft to enhance their serviceability may protect them for a changing future in which satellite servicing may become mainstream. ESA aims to conceive and promote standard refuelling provisions that can be installed in present and future European commercial geostationary orbit (GEO) satellite platforms and scientific spacecraft. For this purpose ESA has started the ASSIST activity addressing the analysis, design and validation of internal provisions (such as modifications to fuel, gas, electrical and data architecture to allow servicing) and external provisions (such as integrated berthing fixtures with peripheral electrical, gas, liquid connectors, leak check systems and corresponding optical and radio markers for cooperative rendezvous and docking). This refuelling approach is being agreed with European industry (OHB, Thales Alenia Space) and expected to be consolidated with European commercial operators as a first step to become an international standard; this approach is also being considered for on-orbit servicing spacecraft, such as the SpaceTug, by Airbus DS. This paper describes in detail the operational means, structure, geometry and accommodation of the system. Internal and external provisions will be designed with the minimum possible impact on the current architecture of GEO satellites without introducing additional risks in the development and commissioning of the satellite. End-effector and berthing fixtures are being designed in the range of few

  10. The development of a UGV-mounted automated refueling system for VTOL UAVs

    Science.gov (United States)

    Wills, Mike; Burmeister, Aaron; Nelson, Travis; Denewiler, Thomas; Mullens, Kathy

    2006-05-01

    This paper describes the latest efforts to develop an Automated UAV Mission System (AUMS) for small vertical takeoff and landing (VTOL) unmanned air vehicles (UAVs). In certain applications such as force protection, perimeter security, and urban surveillance a VTOL UAV can provide far greater utility than fixed-wing UAVs or ground-based sensors. The VTOL UAV can operate much closer to an object of interest and can provide a hover-and-stare capability to keep its sensors trained on an object, while the fixed wing UAV would be forced into a higher altitude loitering pattern where its sensors would be subject to intermittent blockage by obstacles and terrain. The most significant disadvantage of a VTOL UAV when compared to a fixed-wing UAV is its reduced flight endurance. AUMS addresses this disadvantage by providing forward staging, refueling, and recovery capabilities for the VTOL UAV through a host unmanned ground vehicle (UGV), which serves as a launch/recovery platform and service station. The UGV has sufficient payload capacity to carry UAV fuel for multiple launch, recovery, and refuel iterations. The UGV also provides a highly mobile means of forward deploying a small UAV into hazardous areas unsafe for personnel, such as chemically or biologically contaminated areas. Teaming small UAVs with large UGVs can decrease risk to personnel and expand mission capabilities and effectiveness. There are numerous technical challenges being addressed by these development efforts. Among the challenges is the development and integration of a precision landing system compact and light enough to allow it to be mounted on a small VTOL UAV while providing repeatable landing accuracy to safely land on the AUMS. Another challenge is the design of a UGV-transportable, expandable, self-centering landing pad that contains hardware and safety devices for automatically refueling the UAV. A third challenge is making the design flexible enough to accommodate different types of VTOL UAVs

  11. Evaluation of potential severe accidents during low power and shutdown operations at Grand Gulf, Unit 1: Evaluation of severe accident risks for plant operational state 5 during a refueling outage. Supporting MELCOR calculations, Volume 6, Part 2

    Energy Technology Data Exchange (ETDEWEB)

    Kmetyk, L.N.; Brown, T.D. [Sandia National Labs., Albuquerque, NM (United States)

    1995-03-01

    To gain a better understanding of the risk significance of low power and shutdown modes of operation, the Office of Nuclear Regulatory Research at the NRC established programs to investigate the likelihood and severity of postulated accidents that could occur during low power and shutdown (LP&S) modes of operation at commercial nuclear power plants. To investigate the likelihood of severe core damage accidents during off power conditions, probabilistic risk assessments (PRAs) were performed for two nuclear plants: Unit 1 of the Grand Gulf Nuclear Station, which is a BWR-6 Mark III boiling water reactor (BWR), and Unit 1 of the Surry Power Station, which is a three-loop, subatmospheric, pressurized water reactor (PWR). The analysis of the BWR was conducted at Sandia National Laboratories while the analysis of the PWR was performed at Brookhaven National Laboratory. This multi-volume report presents and discusses the results of the BWR analysis. The subject of this part presents the deterministic code calculations, performed with the MELCOR code, that were used to support the development and quantification of the PRA models. The background for the work documented in this report is summarized, including how deterministic codes are used in PRAS, why the MELCOR code is used, what the capabilities and features of MELCOR are, and how the code has been used by others in the past. Brief descriptions of the Grand Gulf plant and its configuration during LP&S operation and of the MELCOR input model developed for the Grand Gulf plant in its LP&S configuration are given.

  12. Metamodel-assisted evolutionary algorithms for the unit commitment problem with probabilistic outages

    Energy Technology Data Exchange (ETDEWEB)

    Georgopoulou, Chariklia A.; Giannakoglou, Kyriakos C. [National Technical University of Athens, School of Mechanical Engineering, Lab. of Thermal Turbomachines, Parallel CFD and Optimization Unit, P.O. Box 64069, Athens 157 10 (Greece)

    2010-05-15

    An efficient method for solving power generating unit commitment (UC) problems with probabilistic unit outages is proposed. It is based on a two-level evolutionary algorithm (EA) minimizing the expected total operating cost (TOC) of a system of power generating units over a scheduling period, with known failure and repair rates of each unit. To compute the cost function value of each EA population member, namely a candidate UC schedule, a Monte Carlo simulation must be carried out. Some thousands of replicates are generated according to the units' outage and repair rates and the corresponding probabilities. Each replicate is represented by a series of randomly generated availability and unavailability periods of time for each unit and the UC schedule under consideration accordingly. The expected TOC is the average of the TOCs of all Monte Carlo replicates. Therefore, the CPU cost per Monte Carlo evaluation increases noticeably and so does the CPU cost of running the EA. To reduce it, the use of a metamodel-assisted EA (MAEA) with on-line trained surrogate evaluation models or metamodels (namely, radial-basis function networks) is proposed. A novelty of this method is that the metamodels are trained on a few ''representative'' unit outage scenarios selected among the Monte Carlo replicates generated once during the optimization and, then, used to predict the expected TOC. Based on this low cost, approximate pre-evaluation, only a few top individuals within each generation undergo Monte Carlo simulations. The proposed MAEA is demonstrated on test problems and shown to drastically reduce the CPU cost, compared to EAs which are exclusively based on Monte Carlo simulations. (author)

  13. Outage probability analysis of a secondary user in an underlay dual hop cognitive amplify and forward relay network

    Directory of Open Access Journals (Sweden)

    Kiran Chandra

    2016-09-01

    Full Text Available This paper presents the performance evaluation of a secondary user (SU in an underlay cognitive dual-hop relaying system considering instantaneous as well as average channel information of the interfering links (from the secondary source and relay to the primary receiver and the data link from the secondary source to relay, to calculate transmit power and amplifying gain of secondary system. Comparison of above mentioned cases is done for two different scenarios – with direct path and without direct path. We evaluate the performance considering two different diversity techniques namely as selection combining (SC and maximum ratio combining (MRC. The effect of different fading channels (Rayleigh and Nakagami on the outage performance of the SU for the two diversity techniques is also shown. The outage probability of the SU is reduced when the diversity techniques are used (with direct path as compared to the outage probability of SU without direct path. We find that the outage performance is better for instantaneous channel information as compared to average channel information for the links. We observe that MRC provides better performance than SC. Furthermore, this work shows that the outage performance of the SU has been improved when the Nakagami fading channel (m = 2 is considered instead of Rayleigh fading channel.

  14. Efficient Outage Probability Evaluation of Diversity Receivers Over Generalized Gamma Channels

    KAUST Repository

    Ben Issaid, Chaouki

    2016-10-01

    In this paper, we are interested in determining the cumulative distribution function of the sum of generalized Gamma in the setting of rare event simulations. To this end, we present an efficient importance sampling estimator. The main result of this work is the bounded relative property of the proposed estimator. This result is used to accurately estimate the outage probability of multibranch maximum ratio combining and equal gain combining diversity receivers over generalized Gamma fading channels. Selected numerical simulations are discussed to show the robustness of our estimator compared to naive Monte Carlo.

  15. Outage Probability in {\\eta}-{\\mu}/{\\eta}-{\\mu} Interference-limited Scenarios

    CERN Document Server

    Paris, Jose F

    2011-01-01

    In this Correspondence exact closed-form expressions are derived for the outage probability (OP) in scenarios where both the signal of interest (SOI) and the interfering signals experience {\\eta}-{\\mu} fading and the background noise can be neglected. With the only assumption that the {\\mu} parameter is a positive integer number for the interfering signals, the derived expressions are given in elementary terms for maximal ratio combining (MRC) with independent branches. The analysis is also valid when the {\\mu} parameters of the pre-combining SOI power envelopes are positive integer or half-integer numbers and the SOI is formed at the receiver from spatially correlated MRC.

  16. MATCASC: A tool to analyse cascading line outages in power grids

    CERN Document Server

    Koç, Yakup; Araujo, Nuno A M; Warnier, Martijn

    2013-01-01

    Blackouts in power grids typically result from cascading failures. The key importance of the electric power grid to society encourages further research into sustaining power system reliability and developing new methods to manage the risks of cascading blackouts. Adequate software tools are required to better analyze, understand, and assess the consequences of the cascading failures. This paper presents MATCASC, an open source MATLAB based tool to analyse cascading failures in power grids. Cascading effects due to line overload outages are considered. The applicability of the MATCASC tool is demonstrated by assessing the robustness of IEEE test systems and real-world power grids with respect to cascading failures.

  17. Signal Quality Outage Analysis for Ultra-Reliable Communications in Cellular Networks

    DEFF Research Database (Denmark)

    Gerardino, Guillermo Andrés Pocovi; Alvarez, Beatriz Soret; Lauridsen, Mads

    2015-01-01

    , we investigate the potential of several techniques to combat these main threats. The analysis shows that traditional microscopic multiple-input multiple-output schemes with 2x2 or 4x4 antenna configurations are not enough to fulfil stringent reliability requirements. It is revealed how such antenna...... schemes must be complemented with macroscopic diversity as well as interference management techniques in order to ensure the necessary SINR outage performance. Based on the obtained performance results, it is discussed which of the feasible options fulfilling the ultra-reliable criteria are most promising...

  18. Feasibility Study for the K-Area Bingham Pump Outage Pit (643-1G)

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, E.R. [Westinghouse Savannah River Company, AIKEN, SC (United States)

    1997-05-01

    The K-Area Bingham Pump Outage Pit (KBPOP) is one of four BPOP areas at Savannah River Site (SRS), collectively referred to as the BPOP waste unit group. This Feasibility Study (FS) of Remedial Alternatives serves as the lead FS for the BPOP waste unit group. This section identifies the purpose and scope of the FS and presents site background information summarized from the Final Remedial Investigation Report with Baseline Risk Assessment (RI/BRA) WSRC-RP- 95-1555, Rev. 1.2 (WSRC 1997).

  19. Outage Analysis of Opportunistic Cooperative Ad Hoc Networks with Randomly Located Nodes

    Institute of Scientific and Technical Information of China (English)

    Cheng-Wen Xing; Hai-Chuan Ding; Guang-Hua Yang; Shao-Dan Ma; Ze-Song Fei

    2013-01-01

    In this paper,an opportunistic cooperative ad hoc sensor network with randomly located nodes is analyzed.The randomness of nodes' locations is captured by a homogeneous Poisson point process.The effect of imperfect interference cancellation is also taken into account in the analysis.Based on the theory of stochastic geometry,outage probability and cooperative gain are derived.It is demonstrated that explicit performance gain can be achieved through cooperation.The analyses are corroborated by extensive simulation results and the analytical results can thus serve as a guideline for wireless sensor network design.

  20. Outage Probability of SINR for Underlay Cognitive Radio Systems in Nakagami Fading

    Science.gov (United States)

    Jarrouj, Jiana; Blagojevic, Vesna; Ivanis, Predrag

    2014-11-01

    In this paper underlay cognitive radio system is analyzed in Nakagami fading environment, for the case when the available channel state information (CSI) of the link from the secondary transmitter to the primary receiver is outdated. We considered the case when both interference and transmit power constraints are applied. The impact of the co-channel interference that originates from the primary user is analyzed in details. The exact closed-form expressions for probability density function, outage probability, and the moments of signal-to-interference and noise ratio (SINR) at the secondary user's receiver are derived. The analytical expressions are verified by using independent Monte Carlo simulation method.

  1. An Internet of Things Approach to Electrical Power Monitoring and Outage Reporting

    Energy Technology Data Exchange (ETDEWEB)

    Koch, Daniel B [ORNL

    2017-01-01

    The so-called Internet of Things concept has captured much attention recently as ordinary devices are connected to the Internet for monitoring and control purposes. One enabling technology is the proliferation of low-cost, single board computers with built-in network interfaces. Some of these are capable of hosting full-fledged operating systems that provide rich programming environments. Taken together, these features enable inexpensive solutions for even traditional tasks such as the one presented here for electrical power monitoring and outage reporting.

  2. Outage performance of two-way DF relaying systems with a new relay selection metric

    KAUST Repository

    Hyadi, Amal

    2012-04-01

    This paper investigates a new constrained relay selection scheme for two-way relaying systems where two end terminals communicate simultaneously via a relay. The introduced technique is based on the maximization of the weighted sum rate of both users. To evaluate the performance of the proposed system, the outage probability is derived in a general case (where an arbitrary channel is considered), and then over independently but not necessarily identically distributed (i.n.i.d.) Rayleigh fading channels. The analytical results are verified through simulations. © 2012 IEEE.

  3. Outage analysis of interference-limited systems using STBC with co-channel MIMO interferers

    Institute of Scientific and Technical Information of China (English)

    Yongzhao LI; Leonard J.CIMINI,JR.; Nageen HIMAYAT

    2009-01-01

    The performance of Space-Time Block Coding (STBC) with co-channel MIMO interference is investigated.For an interference-limited environment, the closed-form ex-pressions for the probability density functions of the signal-to-interference ratio are derived and applied to analyze the outage probability with three typical types of co-channel MIMO interferers: STBC, open-loop spatial multiplexing and closed-loop spatial multiplexing. Both theoretical anal-yses and simulation results show that the performance of STBC is independent of the MIMO modes used in the in-terfering links.

  4. Exact outage analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel

    2010-11-01

    In this paper, we investigate a dual-hop decode-andforward opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we derive exact closed-form expression for the outage probability based on the exact statistics of each hop. Furthermore, we perform asymptotic analysis and we deduce the diversity order of the scheme. We validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures. © 2010 IEEE.

  5. A study on assessment methodology of surveillance test interval and allowed outage time

    Energy Technology Data Exchange (ETDEWEB)

    Che, Moo Seong; Cheong, Chang Hyeon; Lee, Byeong Cheol [Seoul Nationl Univ., Seoul (Korea, Republic of)] (and others)

    1996-07-15

    The objectives of this study is the development of methodology by which assessing the optimizes Surveillance Test Interval(STI) and Allowed Outage Time(AOT) using PSA method that can supplement the current deterministic methods and the improvement of Korea nuclear power plants safety. In the first year of this study, the survey about the assessment methodologies, modeling and results performed by domestic and international researches is performed as the basic step before developing the assessment methodology of this study. The assessment methodology that supplement the revealed problems in many other studies is presented and the application of new methodology into the example system assures the feasibility of this method.

  6. Outage and ser performance of an opportunistic multi-user underlay cognitive network

    KAUST Repository

    Khan, Fahd Ahmed

    2012-10-01

    Consider a multi-user underlay cognitive network where multiple cognitive users concurrently share the spectrum with a primary network and a single secondary user is selected for transmission. The channel is assumed to have independent but not identical Nakagami-m fading. Closed form expressions for the outage performance and the symbol-error-rate performance of the opportunistic multi-user secondary network are derived when a peak interference power constraint is imposed on the secondary network in addition to the limited peak transmit power of each secondary user. © 2012 IEEE.

  7. Outage and BER analysis for ultrawideband-based WPAN in Nakagami-m fading channels

    KAUST Repository

    Mehbodniya, Abolfazl

    2011-09-01

    This paper presents a performance analysis of multiband orthogonal frequency-division multiplexing (MB-OFDM) in ultra wideband (UWB)-based personal area networks (UPANs). A UPAN consists of devices with different UWB technologies at the physical layer. Approximate expressions for the outage probability and average bit error rate (BER) are derived in closed form for the MB-OFDM target receiver, taking into account multi-user interference (MUI), as well as external interference in the form of time-hopping (TH) and direct-sequence (DS) UWB signals. © 2010 IEEE.

  8. Operational transparency: an advanced safeguards strategy for future on-load refuelled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Whitlock, J.J. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Trask, D. [Atomic Energy of Canada Limited, Fredericton, New Brunswick (Canada)

    2012-03-15

    The IAEA's system for tracking fuel movement in an on-load refuelled heavy-water reactor is robust, but an opportunity remains to exploit the wealth of data streaming from the reactor vault during operation and provide real-time, third-party monitoring of reactor status and history. This concept of Operational Transparency would require that large amounts of operational data be reduced in near-real time to a small subset of high-level information. Operational Transparency would enhance the IAEA's ability to monitor the state of the core to an unprecedented level. This paper provides an overview of the novel concept of Operational Transparency in heavy water reactors, using potential application to CANDU reactors as an example, and explores some of the technical challenges that will need to be solved for efficient implementation. (author)

  9. Detection and Tracking Strategies for Autonomous Aerial Refuelling Tasks Based on Monocular Vision

    Directory of Open Access Journals (Sweden)

    Yingjie Yin

    2014-07-01

    Full Text Available Detection and tracking strategies based on monocular vision are proposed for autonomous aerial refuelling tasks. The drogue attached to the fuel tanker aircraft has two important features. The grey values of the drogue's inner part are different from the external umbrella ribs, as shown in the image. The shape of the drogue's inner dark part is nearly circular. According to crucial prior knowledge, the rough and fine positioning algorithms are designed to detect the drogue. Particle filter based on the drogue's shape is proposed to track the drogue. A strategy to switch between detection and tracking is proposed to improve the robustness of the algorithms. The inner dark part of the drogue is segmented precisely in the detecting and tracking process and the segmented circular part can be used to measure its spatial position. The experimental results show that the proposed method has good performance in real-time and satisfied robustness and positioning accuracy.

  10. Rethinking cardiac metabolism: metabolic cycles to refuel and rebuild the failing heart.

    Science.gov (United States)

    Taegtmeyer, Heinrich; Lubrano, Genna

    2014-01-01

    The heart is a self-renewing biological pump that converts chemical energy into mechanical energy. The entire process of energy conversion is subject to complex regulation at the transcriptional, translational and post-translational levels. Within this system, energy transfer occurs with high efficiency, facilitated by a series of compound-conserved cycles. At the same time, the constituent myocardial proteins themselves are continuously made and degraded in order to adjust to changes in energy demand and changes in the extracellular environment. We recently have identified signals arising from intermediary metabolism that regulate the cycle of myocardial protein turnover. Using a new conceptual framework, we discuss the principle of metabolic cycles and their importance for refueling and for rebuilding the failing heart.

  11. Research and Development of a PEM Fuel Cell, Hydrogen Reformer, and Vehicle Refueling Facility

    Energy Technology Data Exchange (ETDEWEB)

    Edward F. Kiczek

    2007-08-31

    Air Products and Chemicals, Inc. has teamed with Plug Power, Inc. of Latham, NY, and the City of Las Vegas, NV, to develop, design, procure, install and operate an on-site hydrogen generation system, an alternative vehicle refueling system, and a stationary hydrogen fuel cell power plant, located in Las Vegas. The facility will become the benchmark for validating new natural gas-based hydrogen systems, PEM fuel cell power generation systems, and numerous new technologies for the safe and reliable delivery of hydrogen as a fuel to vehicles. Most important, this facility will serve as a demonstration of hydrogen as a safe and clean energy alternative. Las Vegas provides an excellent real-world performance and durability testing environment.

  12. Outage Analysis of Dual-hop Cognitive Networks with Relay Selection over Nakagami-m Fading Environment

    Science.gov (United States)

    Zhang, Zongsheng; Pi, Xurong

    2014-09-01

    In this paper, we investigate the outage performance of decode-and-forward cognitive relay networks for Nakagami-m fading channels, with considering both best relay selection and interference constraints. Focusing on the relay selection and making use of the underlay cognitive approach, an exact closed-form outage probability expression is derived in an independent, non-identical distributed Nakagami-m environment. The closed-form outage probability provides an efficient means to evaluate the effects of the maximum allowable interference power, number of cognitive relays, and channel conditions between the primary user and cognitive users. Finally, we present numerical results to validate the theory analysis. Moreover, from the simulation results, we obtain that the system can obtain the full diversity.

  13. Outage Performance of Cooperative Relay Selection with Multiple Source and Destination Antennas over Dissimilar Nakagami-m Fading Channels

    Science.gov (United States)

    Lee, Wooju; Yoon, Dongweon

    Cooperative relay selection, in which one of multiple relays is selected to retransmit the source signal to the destination, has received considerable attention in recent years, because it is a simple way to obtain cooperative diversity in wireless networks. The exact expression of outage probability for a decode-and-forward cooperative relay selection with multiple source and destination antennas over Rayleigh fading channels was recently derived in [9]. In this letter, we derive the exact expressions of outage probability and diversity-multiplexing tradeoff over independent and non-identically distributed Nakagami-m fading channels as an extension of [9]. We then analyze the effects of various parameters such as fading conditions, number of relays, and number of source and destination antennas on the outage probability.

  14. Outage probability of dual-hop partial relay selection with feedback delay in the presence of interference

    KAUST Repository

    Al-Qahtani, Fawaz S.

    2011-09-01

    In this paper, we investigate the outage performance of a dual-hop relaying systems with partial relay selection and feedback delay. The analysis considers the case of Rayleigh fading channels when the relaying station as well as the destination undergo mutually independent interfering signals. Particularly, we derive the cumulative distribution function (c.d.f.) of a new type of random variable involving sum of multiple independent exponential random variables, based on which, we present closed-form expressions for the exact outage probability of a fixed amplify-and-forward (AF) and decode-and-forward (DF) relaying protocols. Numerical results are provided to illustrate the joint effect of the delayed feedback and co-channel interference on the outage probability. © 2011 IEEE.

  15. Outage performance of opportunistic two-way amplify-and-forward relaying with outdated channel state information

    KAUST Repository

    Hwang, Kyusung

    2013-09-01

    In this paper, we study the outage performance of an amplify-and-forward (AF)-based two-way relaying (TWR) system with multiple relays where a single relay selection is performed based on outdated channel state information (CSI). Specifically, we propose a single relay selection scheme in AF-based TWR system under outdated CSI conditions. With this policy, we offer a statistical analysis of the signal-to-noise ratio per hop and analyze the outage probability with asymmetric outage thresholds based on CSI-assisted AF protocol. Additionally, we provide the exact and asymptotic expressions based on the provided statistical/joint statistical analyses of a dual-hop AF transmission. Finally, we verify our analytical results with some selected computer-based simulation results. © 1972-2012 IEEE.

  16. Fast Outage Probability Simulation for FSO Links with a Generalized Pointing Error Model

    KAUST Repository

    Issaid, Chaouki Ben

    2017-02-07

    Over the past few years, free-space optical (FSO) communication has gained significant attention. In fact, FSO can provide cost-effective and unlicensed links, with high-bandwidth capacity and low error rate, making it an exciting alternative to traditional wireless radio-frequency communication systems. However, the system performance is affected not only by the presence of atmospheric turbulences, which occur due to random fluctuations in the air refractive index but also by the existence of pointing errors. Metrics, such as the outage probability which quantifies the probability that the instantaneous signal-to-noise ratio is smaller than a given threshold, can be used to analyze the performance of this system. In this work, we consider weak and strong turbulence regimes, and we study the outage probability of an FSO communication system under a generalized pointing error model with both a nonzero boresight component and different horizontal and vertical jitter effects. More specifically, we use an importance sampling approach which is based on the exponential twisting technique to offer fast and accurate results.

  17. Inducement of IGA/SCC in Inconel 600 steam generator tubing during unit outages

    Energy Technology Data Exchange (ETDEWEB)

    Durance, D.; Sedman, K. [Bruce Power, Tiverton, Ontario (Canada); Roberts, J. [CANTECH Associates Ltd., Burlington, Ontario (Canada); King, P. [Babcock and Wilcox Canada, Cambridge, Ontario (Canada); Gorman, J. [Dominion Engineering, Reston, VA (United States); Allen, R. [Kinectrics, Inc., Toronto, Ontario (Canada)

    2008-07-01

    The degradation of Unit 4 SG tubing by IGA/SCC has limited both the operating period and end of life predictions for Unit 4 since restart in late 2003. The circumferential IGA/SCC has been most significant in SG4 with substantial increases in both initiation and growth rates from 2005 through the spring of 2007. A detailed review of the occurrence of circumferential OD IGA/SCC at the RTZ in the HL TTS region of Bruce 4 steam generator tubes has led a conclusion that it is probable that the IGA/SCC has been the result of attack by partially reduced sulfur species such as tetrathionates and thiosulfates during periods of low temperature exposure. It is believed that attack of this type has mostly likely occurred during startup evolutions following outages as the result the development of aggressive reduced sulfur species in the TTS region during periods when the boilers were fully drained for maintenance activities. The modification of outage practices to limit secondary side oxygen ingress in the spring of 2007 has apparently arrested the degradation and has had significant affects on the allowable operating interval and end of life predictions for the entire unit. (author)

  18. Magnetic survey of the R-Area Bingham Pump Outage Pits

    Energy Technology Data Exchange (ETDEWEB)

    Cumbest, R.J.

    1995-05-01

    The R-Area Bingham Pump Outage pits are a series of parallel trenches in which construction materials were buried. The suspected locations of three of the trenches are marked by HP orange waste unit marker balls, in addition to concrete pit monuments that were placed based on historical information. In order to confirm the locations of the trenches and to evaluate the presence of other buried ferric material, a magnetic survey was conducted at the R-Area Bingham Pump Outage Pits. The survey is defined by lines spaced 10 ft apart oriented subperpendicular to the trench elongation direction, with survey stations spaced at 5-ft intervals along each line. This resulted in a 10-ft by 5-ft rectangular grid node pattern. The magnetic survey resolved at least four linear arrays of magnetic field and gradient anomalies that result from buried ferric material. Three of the linear arrays correspond to suspected trench locations as delineated by HP orange marker balls and pit monuments. However, a fourth linear anomaly occurs between two of the suspected trenches, indicating the presence of an unmarked trench. In addition to linear anomalies that are associated with the trenches, other isolated anomalies occur due to ferric sources that can be identified on the surface, such as signs, monuments, and metal pipes.`

  19. Outage performance analysis of underlay cognitive RF and FSO wireless channels

    KAUST Repository

    Ansari, Imran Shafique

    2014-09-01

    In this work, the outage performance analysis of a dual-hop transmission system composed of asymmetric radio frequency (RF) channel cascaded with a free-space optical (FSO) link is presented. For the RF link, an underlay cognitive network is considered where the secondary users share the spectrum with licensed primary users. Indoor femtocells act as a practical example for such networks. More specifically, it is assumed that the RF link applies power control to maintain the interference at the primary network below a predetermined threshold. While the RF channel is modeled by the Rayleigh fading distribution, the FSO link is modeled by a unified Gamma-Gamma turbulence distribution. The FSO link accounts for pointing errors and both types of detection techniques (i.e. heterodyne detection as well as intensity modulation/direct detection (IM/DD)). With this model, a new exact closed-form expression is derived for the outage probability of the end-To-end signal-To-noise ratio of these systems in terms of the Meijer\\'s G function and the Fox\\'s H functions under fixed amplify-and-forward relay scheme. All new analytical results are verified via computer-based Monte-Carlo simulations and are illustrated by some selected numerical results.

  20. Power Allocation for Outage Minimization in Cognitive Radio Networks with Limited Feedback

    CERN Document Server

    He, Yuan Yuan

    2011-01-01

    We address an optimal transmit power allocation problem that minimizes the outage probability of a secondary user (SU) who is allowed to coexist with a primary user (PU) in a narrowband spectrum sharing cognitive radio network, under a long term average transmit power constraint at the secondary transmitter (SU-TX) and an average interference power constraint at the primary receiver (PU-RX), with quantized channel state information (CSI) (including both the channels from SU-TX to SU-RX, denoted as $g_1$ and the channel from SU-TX to PU-RX, denoted as $g_0$) at the SU-TX. The optimal quantization regions in the vector channel space is shown to have a 'stepwise' structure. With this structure, the above outage minimization problem can be explicitly formulated and solved by employing the Karush-Kuhn-Tucker (KKT) necessary optimality conditions to obtain a locally optimal quantized power codebook. A low-complexity near-optimal quantized power allocation algorithm is derived for the case of large number of feedbac...

  1. Coordinate Update Algorithms for Robust Power Loading for the MU-MISO Downlink With Outage Constraints

    Science.gov (United States)

    Sohrabi, Foad; Davidson, Timothy N.

    2016-06-01

    We consider the problem of power allocation for the single-cell multi-user (MU) multiple-input single-output (MISO) downlink with quality-of-service (QoS) constraints. The base station acquires an estimate of the channels and, for a given beamforming structure, designs the power allocation so as to minimize the total transmission power required to ensure that target signal-to-interference-and-noise ratios at the receivers are met, subject to a specified outage probability. We consider scenarios in which the errors in the base station's channel estimates can be modelled as being zero-mean and Gaussian. Such a model is particularly suitable for time division duplex (TDD) systems with quasi-static channels, in which the base station estimates the channel during the uplink phase. Under that model, we employ a precise deterministic characterization of the outage probability to transform the chance-constrained formulation to a deterministic one. Although that deterministic formulation is not convex, we develop a coordinate descent algorithm that can be shown to converge to a globally optimal solution when the starting point is feasible. Insight into the structure of the deterministic formulation yields approximations that result in coordinate update algorithms with good performance and significantly lower computational cost. The proposed algorithms provide better performance than existing robust power loading algorithms that are based on tractable conservative approximations, and can even provide better performance than robust precoding algorithms based on such approximations.

  2. Fundamental Limits of Parallel Optical Wireless Channels: Capacity Results and Outage Formulation

    KAUST Repository

    Chaaban, Anas

    2016-10-26

    Multi-channel (MC) optical wireless communication (OWC) systems employing wave-division multiplexing for outdoors free-space optical communications, or multi-user timedivision multiple access for indoors visible-light communications, e.g., can be modeled as parallel channels. Multi-input multioutput OWC systems can also be transformed, possibly with some performance loss, to parallel channels using pre-/postcoding. Studying the performance of such MC-OWC systems requires characterizing the capacity of the underlying parallel channels. In this paper, upper and lower bounds on the capacity of constant parallel OWC channels with a total average intensity constraint are derived. Then, the paper focuses on finding intensity allocations that maximize the lower bounds given channel-state information at the transmitter (CSIT). Due to its nonconvexity, the KKT conditions are used to describe a list of candidate allocations. Instead searching exhaustively for the best solution, low-complexity near-optimal algorithms are proposed. The resulting optimized lower bound nearly coincides with capacity at high signal-to-noise ratio (SNR). Under a quasi-static channel model and in the absence of CSIT, outage probability upper and lower bounds are derived. Those bounds also meet at high SNR, thus characterizing the outage capacity in this regime. Finally, the results are extended to a system with both average and peak intensity constraints.

  3. On Outage Probability and Diversity-Multiplexing Tradeoff in MIMO Relay Channels

    CERN Document Server

    Loyka, Sergey

    2011-01-01

    Fading MIMO relay channels are studied analytically, when the source and destination are equipped with multiple antennas and the relays have a single one. Compact closed-form expressions are obtained for the outage probability under i.i.d. and correlated Rayleigh-fading links. Low-outage approximations are derived, which reveal a number of insights, including the impact of correlation, of the number of antennas, of relay noise and of relaying protocol. The effect of correlation is shown to be negligible, unless the channel becomes almost fully correlated. The SNR loss of relay fading channels compared to the AWGN channel is quantified. The SNR-asymptotic diversity-multiplexing tradeoff (DMT) is obtained for a broad class of fading distributions, including, as special cases, Rayleigh, Rice, Nakagami, Weibull, which may be non-identical, spatially correlated and/or non-zero mean. The DMT is shown to depend not on a particular fading distribution, but rather on its polynomial behavior near zero, and is the same ...

  4. Exploiting Outage and Error Probability of Cooperative Incremental Relaying in Underwater Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Hina Nasir

    2016-07-01

    Full Text Available This paper embeds a bi-fold contribution for Underwater Wireless Sensor Networks (UWSNs; performance analysis of incremental relaying in terms of outage and error probability, and based on the analysis proposition of two new cooperative routing protocols. Subject to the first contribution, a three step procedure is carried out; a system model is presented, the number of available relays are determined, and based on cooperative incremental retransmission methodology, closed-form expressions for outage and error probability are derived. Subject to the second contribution, Adaptive Cooperation in Energy (ACE efficient depth based routing and Enhanced-ACE (E-ACE are presented. In the proposed model, feedback mechanism indicates success or failure of data transmission. If direct transmission is successful, there is no need for relaying by cooperative relay nodes. In case of failure, all the available relays retransmit the data one by one till the desired signal quality is achieved at destination. Simulation results show that the ACE and E-ACE significantly improves network performance, i.e., throughput, when compared with other incremental relaying protocols like Cooperative Automatic Repeat reQuest (CARQ. E-ACE and ACE achieve 69% and 63% more throughput respectively as compared to CARQ in hard underwater environment.

  5. Analysis of heterogeneous boron dilution transients during outages with APROS 3D nodal core model

    Energy Technology Data Exchange (ETDEWEB)

    Kuopanportti, Jaakko [Fortum Power and Heat Ltd, Nuclear Production, Fortum (Finland)

    2015-09-15

    A diluted water plug can form inside the primary coolant circuit if the coolant flow has stopped at least temporarily. The source of the clean water can be external or the fresh water can build up internally during boiling/condensing heat transfer mode, which can occur if the primary coolant inventory has decreased enough during an accident. If the flow restarts in the stagnant primary loop, the diluted water plug can enter the reactor core. During outages after the fresh fuel has been loaded and the temperature of the coolant is low, the dilution potential is the highest because the critical boron concentration is at the maximum. This paper examines the behaviour of the core as clean or diluted water plugs of different sizes enter the core during outages. The analysis were performed with the APROS 3D nodal core model of Loviisa VVER-440, which contains an own flow channel and 10 axial nodes for each fuel assembly. The widerange cross section data was calculated with CASMO-4E. According to the results, the core can withstand even large pure water plugs without fuel failures on natural circulation. The analyses emphasize the importance of the simulation of the backflows inside the core when the reactor is on natural circulation.

  6. An Efficient Simulation Scheme of the Outage Probability with Co-Channel Interference

    KAUST Repository

    Rached, Nadhir B.

    2016-03-28

    © 2015 IEEE. The outage probability (OP) of the signal-to-interference-plus-noise ratio (SINR) is an important metric used to evaluate the performance of wireless communication systems operating over fading channels. One major difficulty toward assessing the OP is that, in most of the realistic scenarios, closed-form expressions cannot be derived. This is for instance the case of Log-normal fading environments, in which evaluating the OP of the SINR amounts to computing the probability that a sum of correlated Log-normal variates exceeds a given threshold. Since such a probability is not known to admit a closed-form expression, it has thus far been evaluated by several approximation techniques, the accuracies of which are unfortunately not guaranteed in the interesting region of small outage probabilities. For these regions, simulation techniques based on variance reduction algorithms can represent a good alternative, being well-recognized to be quick and highly accurate for estimating rare event probabilities. This constitutes the major motivation behind our work. More specifically, we propose an efficient importance sampling approach which is based on a covariance matrix scaling technique and illustrate its computational gain over naive Monte Carlo simulations through some selected simulation results.

  7. Outage Analysis of Practical FSO/RF Hybrid System With Adaptive Combining

    KAUST Repository

    Rakia, Tamer

    2015-08-01

    Hybrid free-space optical (FSO)/radio-frequency (RF) systems have emerged as a promising solution for high-data-rate wireless transmission. We present and analyze a transmission scheme for the hybrid FSO/RF communication system based on adaptive combining. Specifically, only FSO link is active as long as the instantaneous signal-to-noise ratio (SNR) at the FSO receiver is above a certain threshold level. When it falls below this threshold level, the RF link is activated along with the FSO link and the signals from the two links are combined at the receiver using a dual-branch maximal ratio combiner. Novel analytical expression for the cumulative distribution function (CDF) of the received SNR for the proposed hybrid system is obtained. This CDF expression is used to study the system outage performance. Numerical examples are presented to compare the outage performance of the proposed hybrid FSO/RF system with that of the FSO-only and RF-only systems. © 1997-2012 IEEE.

  8. Discounted Duration Calculus

    DEFF Research Database (Denmark)

    Ody, Heinrich; Fränzle, Martin; Hansen, Michael Reichhardt

    2016-01-01

    To formally reason about the temporal quality of systems discounting was introduced to CTL and LTL. However, these logic are discrete and they cannot express duration properties. In this work we introduce discounting for a variant of Duration Calculus. We prove decidability of model checking...... for a useful fragment of discounted Duration Calculus formulas on timed automata under mild assumptions. Further, we provide an extensive example to show the usefulness of the fragment....

  9. Innovation on Energy Power Technology (15)Great Advances in Power System Stabilizing Technology triggered by the Wide-area Outage

    Science.gov (United States)

    Egawa, Masanao

    On July 23, 1987, a very hot day, the largest wide-area power outage occurred in Kanto-Area, Japan. The cause was a voltage collapse on the bulk power network of Tokyo Electric Power Company, due to the abnormal rate of demand rising following resume after lunch break. Aggressive studies on voltage collapse throughout industry and university have led to great advances in power system stability. This essay describes the detail record of the outage, the applied countermeasures, and the inside story when the multiple voltage solutions of power flow on actual power system were found out for the first time.

  10. 汽车加油机器人关键技术分析%Analysis of Key Technology of Refueling Robot for Automobile

    Institute of Scientific and Technical Information of China (English)

    陈雁; 陈文卓; 黎波; 陈森林

    2015-01-01

    Due to the fact that conventional refueling methods may endanger operators when they refuel cars and that operat⁃ing conditions in gas station are extremely severe in winters and summers, it is urgent to intelligentize gas stations with the refueling robot. The research progress of the refueling robot for automobile at home and abroad is introduced in detail first. The characteristics of its operating target and environment are pointed out, especially, the differences among targets, dangers during operation and varia⁃tion in operation environment. The present technologies of refueling robot for automobile are discussed respectively:refueling mech⁃anism, refueling interface and identification and localization technology. Optimization of refueling mechanism, security control and intelligent identification and localization are proposed as the developing trend of this research.%传统加油模式使操作人员易受有毒易燃油气的侵害,而且严冬酷暑时加油站作业环境恶劣,因此在加油站配置机器人实现智能化加油变得十分迫切。介绍了国内外汽车加油机器人的研究进展,指出其作业对象的差异性、环境的多变性以及作业过程的危险性。分析了当前汽车加油机器人所采用的加油机构、加注接口以及识别与定位技术的特点,指出加油机构优化、安全控制、智能识别与定位研究是汽车加油机器人发展的方向。

  11. Icon Duration and Development.

    Science.gov (United States)

    Gummerman, Kent; And Others

    In this study, developmental changes in duration of the icon (visual sensory store) were investigated with three converging tachistoscopic tasks. (1) Stimulus interuption detection (SID), a variation of the two-flash threshold method, was performed by 29 first- and 32 fifth-graders, and 32 undergraduates. Icon duration was estimated by stimulus…

  12. Evaluation of Particle Counter Technology for Detection of Fuel Contamination Detection Utilizing Advanced Aviation Forward Area Refueling System

    Science.gov (United States)

    2014-01-24

    UNCLASSIFIED 6 UNCLASSIFIED Receipt Vehicle Fuel Tank Fuel Injector Aviation Fuel DEF (AUST) 5695B 18/16/13 Parker 18/16/13 14/10/7 Pamas... Alcohol to Jet (ATJ) fuel flight testing at Redstone Test Center, TARDEC was afforded the opportunity to evaluate light obscuration particle counters on...Advanced Aviation Forward Area Refueling System (AAFARS) setup for Alcohol to Jet (ATJ) fuel flight testing. Figure 2. AAFARS fuel sampling port

  13. Green refuel. Fitting in alternate fuels in the refuelling and automotive fuel distribution infrastructure; Groen tanken. Inpassing van alternatieve brandstoffen in de tank- en distributie infrastructuur

    Energy Technology Data Exchange (ETDEWEB)

    Roeterdink, W.G.; Uyterlinde, M.A.; Kroon, P.; Hanschke, C.B. [ECN Beleidsstudies, Petten (Netherlands)

    2010-08-15

    For the department of Housing, Spatial Planning and the Environment (VROM) an overview was made of the current market shares and business cases of alternative fuels, and of main barriers for their large-scale market introduction. In the short term, compressed natural gas has the best business case, even though the investment costs for the infrastructure are relatively high. The current pump price of bio-ethanol is too high to be attractive for consumers; however, the government has announced an excise tax cut. Although the investment costs of a biofuel pump are relatively low, the business case for bio-ethanol, even with the tax cut, will still be not as favourable as the business case for natural gas. In the long term, charging points for electricity and/or filling stations for hydrogen have to become available. For hydrogen, the availability and affordability of the fuel cell vehicles is the initial barrier. A refuelling infrastructure is expected to be supported through truck distribution of liquid hydrogen, or with pipelines. Similarly, electric vehicles are still in the demonstration phase. Currently, it is unclear what the tax regime on electricity for mobility will be, but the profit margin of current consumer prices is too small to make an investment in charging points viable. In addition, there is still much uncertainty about the future charging infrastructure (fast charging or battery swapping) and recharging behaviour (at night) [Dutch] Het Ministerie van VROM heeft behoefte aan een verkenning van de inpasbaarheid van alternatieve brandstoffen in de tankinfrastructuur. Het gaat daarbij zowel om een verkenning van de huidige situatie, als om het lange termijn perspectief. In deze studie zijn de marktbarrieres voor de introductie van alternatieve brandstoffen in de distributie- en tankinfrastructuur geevalueerd, waarbij voornamelijk naar economische aspecten is gekeken, vanuit het perspectief van zowel de brandstofleverancier als de consument. Daarnaast is

  14. Emergency preparedness for power outages and wi-fi loss: tips for students and educators of online courses.

    Science.gov (United States)

    Heithaus, Teresa

    2015-01-01

    Severe weather can impact online education due to a loss of power and Internet access that can last hours or weeks. Planning for such losses is essential to enable participation in the online classroom. This article discusses measures that can be used to maintain an online presence in the event of a power outage or loss of Wi-Fi.

  15. Are Older Adults Prepared to Ensure Food Safety during Extended Power Outages and Other Emergencies?: Findings from a National Survey

    Science.gov (United States)

    Kosa, Katherine M.; Cates, Sheryl C.; Karns, Shawn; Godwin, Sandria L.; Coppings, Richard J.

    2012-01-01

    Natural disasters and other emergencies can cause an increased risk of foodborne illness. We conducted a nationally representative survey to understand consumers' knowledge and use of recommended practices during/after extended power outages and other emergencies. Because older adults are at an increased risk for foodborne illness, this paper…

  16. Are Older Adults Prepared to Ensure Food Safety during Extended Power Outages and Other Emergencies?: Findings from a National Survey

    Science.gov (United States)

    Kosa, Katherine M.; Cates, Sheryl C.; Karns, Shawn; Godwin, Sandria L.; Coppings, Richard J.

    2012-01-01

    Natural disasters and other emergencies can cause an increased risk of foodborne illness. We conducted a nationally representative survey to understand consumers' knowledge and use of recommended practices during/after extended power outages and other emergencies. Because older adults are at an increased risk for foodborne illness, this paper…

  17. 47 CFR 4.11 - Notification and initial and final communications outage reports that must be filed by...

    Science.gov (United States)

    2010-10-01

    ... Notification shall provide: The name of the reporting entity; the date and time of onset of the outage; a brief... FEDERAL COMMUNICATIONS COMMISSION GENERAL DISRUPTIONS TO COMMUNICATIONS Reporting Requirements for... and contact telephone number by which the Commission's technical staff may contact the...

  18. Outage Analysis of PLNC Based Bidirectional Relay Network in the presence of I/Q Imbalance

    Directory of Open Access Journals (Sweden)

    V.N.Senthil Kumaran

    2014-08-01

    Full Text Available Bidirectional relay network consists of two sources and a relay, where each node has a single antenna and operates in half duplex mode. The PLNC based OFDM system transmits numerous high data streams through narrow band flat fading subchannels to achieve high spectral efficiency over wide band channels. However in practice, I/Q imbalance is introduced at the radio frequency sections of the nodes affects the orthogonality among the subcarriers. In this paper, the bidirectional relay network is modelled with I/Q imbalance and the outage performance of Orthogonal Frequency Division Multiplexing (OFDM based bidirectional relay network which employs physical layer network coding (PLNC is analyzed in the presence of In-phase and Quadrature (I/Q imbalance at both the time slots.

  19. A A field test for extremity dose assessment during outages at Korean nuclear power plants.

    Science.gov (United States)

    Kim, Hee Geun; Kong, Tae Young

    2013-05-01

    During maintenance on the water chamber of a steam generator, the pressuriser heater and the pressure tube feeder in nuclear power plants, workers are likely to receive high radiation doses due to the severe workplace conditions. In particular, it is expected that workers' hands would receive the highest radiation doses because of their contact with the radioactive materials. In this study, field tests for extremity dose assessments in radiation workers undertaking contact tasks with high radiation doses were conducted during outages at pressurised water reactors and pressurised heavy water reactors in Korea. In the test, the radiation workers were required to wear additional thermoluminescent dosemeters (TLDs) on their backs and wrists and an extremity dosemeter on the finger, as well as a main TLD on the chest while performing the maintenance tasks.

  20. A multi-state model for wind farms considering operational outage probability

    DEFF Research Database (Denmark)

    Cheng, Lin; Liu, Manjun; Sun, Yuanzhang;

    2013-01-01

    power penetration levels. Therefore, a more comprehensive analysis toward WECS as well as an appropriate reliability assessment model are essential for maintaining the reliable operation of power systems. In this paper, the impact of wind turbine outage probability on system reliability is firstly......As one of the most important renewable energy resources, wind power has drawn much attention in recent years. The stochastic characteristics of wind speed lead to generation output uncertainties of wind energy conversion system (WECS) and affect power system reliability, especially at high wind...... developed by considering the following factors: running time, operating environment, operating conditions, and wind speed fluctuations. A multi-state model for wind farms is also established. Numerical results illustrate that the proposed model can be well applied to power system reliability assessment...

  1. Outage Probability of the Gaussian MIMO Free-Space Optical Channel with PPM

    CERN Document Server

    Letzepis, Nick

    2008-01-01

    The free-space optical channel has the potential to facilitate inexpensive, wireless communication with fiber-like bandwidth under short deployment timelines. However, atmospheric effects can significantly degrade the reliability of a free-space optical link. In particular, atmospheric turbulence causes random fluctuations in the irradiance of the received laser beam, commonly referred to as scintillation. The scintillation process is slow compared to the large data rates typical of optical transmission. As such, we adopt a quasi-static block fading model and study the outage probability of the channel under the assumption of orthogonal pulse-position modulation. We investigate the mitigation of scintillation through the use of multiple lasers and multiple apertures, thereby creating a multiple-input multiple output (MIMO) channel. Non-ideal photodetection is also assumed such that the combined shot noise and thermal noise are considered as signal-independent Additive Gaussian white noise. Assuming perfect re...

  2. Outage probability of dual-hop FSO fixed gain relay transmission systems

    KAUST Repository

    Zedini, Emna

    2016-12-24

    In this paper, we analyze the end-to-end performance of dual-hop free-space optical (FSO) fixed gain relaying systems in the presence of atmospheric turbulence as well as pointing errors. More specifically, an exact closed-form expression for the outage probability is presented in terms of the bivariate Fox\\'s H function that accounts for both heterodyne detection as well as intensity modulation with direct detection. At high signal-to-noise ratio (SNR) regime, we provide very tight asymptotic result for this performance metric in terms of simple elementary functions. By using dual-hop FSO relaying, we demonstrate a better system performance as compared to the single FSO link. Numerical and Monte-Carlo simulation results are provided to verify the accuracy of the newly proposed results, and a perfect agreement is observed.

  3. Analysis of 12 electric power system outages/disturbances impacting the Florida Peninsula

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-12-01

    Between January 3 and August 3, 1979, there were 12 occasions on which electric power was curtailed or public appeals were made to customers to reduce their load in Peninsular Florida due to bulk electric power supply problems. The Economic Regulatory Administration (ERA) of the US DOE, pursuant to its electric power supply adequacy and reliability responsibilities, initiated a twofold analysis of the bulk power supply situation in Florida. The first phase of the analysis evaluated the technical and engineering aspects of the overall Florida bulk power supply system with special attention given to the City of Jacksonville's electric system. The second phase evaluated the socioeconomic impacts of the bulk power supply outages on residential customers in Jacksonville. The 12 disturbances are described and a comparative analysis of the causes is presented. (LCL)

  4. Living at the Edge: A Large Deviations Approach to the Outage MIMO Capacity

    CERN Document Server

    Kazakopoulos, P; Moustakas, A L; Caire, G

    2009-01-01

    Using a large deviations approach we calculate the probability distribution of the mutual information of MIMO channels in the limit of large antenna numbers. In contrast to previous methods that only focused at the distribution close to its mean (thus obtaining an asymptotically Gaussian distribution), we calculate the full distribution, including its tails which strongly deviate from the Gaussian behavior near the mean. The resulting distribution interpolates seamlessly between the Gaussian approximation for rates $R$ close to the ergodic value of the mutual information and the approach of Zheng and Tse for large signal to noise ratios $\\rho$. This calculation provides us with a tool to obtain outage probabilities analytically at any point in the $(R, \\rho, N)$ parameter space, as long as the number of antennas $N$ is not too small. In addition, this method also yields the probability distribution of eigenvalues constrained in the subspace where the mutual information per antenna is fixed to $R$ for a given ...

  5. Areva: experiences in outage services; Areva: experiencias en servicios de recarga

    Energy Technology Data Exchange (ETDEWEB)

    Wiemeier, R.; Mueller, N.; Blanco, I. J.

    2010-07-01

    As the world leader in the nuclear industry, Areva is firmly committed to the safe and reliable operation of the Spanish nuclear power plants. Following this commitment, Areva has established the subsidiary Areva NP Services Spain as a local platform to provide nuclear services for the Spanish nuclear power plants. being integrated and supported by the global Areva Group, Areva NP Services Spain is able to offer services solutions to all customers demands while maintaining close and sustainable relationships with them. This integration also allows the Spanish personnel of Areva to employ their skills by working in multinational teams in international projects. This article will present the capacities, and the most important recent national and international project performed by Areva NP Services Spain in the field of outage services. (Author)

  6. On the Outage Behavior of Asynchronous OFDM DF and AF Cooperative Networks

    CERN Document Server

    Torbatian, Mehdi

    2009-01-01

    The outage behavior of various relaying protocols over a general one hop asynchronous cooperative network is examined when orthogonal frequency division multiplexing (OFDM) is used to combat synchronization error among the relays. We consider non-orthogonal selection decode-and-forward (NSDF), orthogonal selection decode-and-forward (OSDF), non-orthogonal amplify-and-forward (NAF), and orthogonal amplify-and-forward (OAF) relaying protocols and analyze the diversity multiplexing gain tradeoff (DMT) in all scenarios. The transmitting nodes cooperatively construct an asynchronous OFDM space-time code by re-sending the source messages over a common time interval and a common frequency bandwidth. It is shown that in decode-and-forward (DF) type protocols, the asynchronous network provides a diversity gain greater than or equal to the one of the corresponding synchronous network in the limit of code word length and throughout the range of multiplexing gain. In amplify-and-forward (AF) type protocols, in which the ...

  7. A Unified Simulation Approach for the Fast Outage Capacity Evaluation over Generalized Fading Channels

    KAUST Repository

    Rached, Nadhir Ben

    2016-01-06

    The outage capacity (OC) is among the most important performance metrics of communication systems over fading channels. The evaluation of the OC, when equal gain combining (EGC) or maximum ratio combining (MRC) diversity techniques are employed, boils down to computing the cumulative distribution function (CDF) of the sum of channel envelopes (equivalently amplitudes) for EGC or channel gains (equivalently squared enveloped/ amplitudes) for MRC. Closed-form expressions of the CDF of the sum of many generalized fading variates are generally unknown and constitute open problems. We develop a unified hazard rate twisting Importance Sampling (IS) based approach to efficiently estimate the CDF of the sum of independent arbitrary variates. The proposed IS estimator is shown to achieve an asymptotic optimality criterion, which clearly guarantees its efficiency. Some selected simulation results are also shown to illustrate the substantial computational gain achieved by the proposed IS scheme over crude Monte Carlo simulations.

  8. Accurate outage analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel

    2011-04-01

    In this paper, we investigate a dual-hop decode-and-forward opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. We first derive the exact statistics of received signal-to-noise (SNR) over each hop with co-located relays, in terms of probability density function (PDF). Then, the PDFs are used to determine very accurate closed-form expression for the outage probability for a transmission rate R. Furthermore, we perform asymptotic analysis and we deduce the diversity order of the scheme. We validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures. © 2011 IEEE.

  9. Outage Performance Analysis of Cooperative Diversity with MRC and SC in Correlated Lognormal Channels

    Directory of Open Access Journals (Sweden)

    Skraparlis D

    2009-01-01

    Full Text Available Abstract The study of relaying systems has found renewed interest in the context of cooperative diversity for communication channels suffering from fading. This paper provides analytical expressions for the end-to-end SNR and outage probability of cooperative diversity in correlated lognormal channels, typically found in indoor and specific outdoor environments. The system under consideration utilizes decode-and-forward relaying and Selection Combining or Maximum Ratio Combining at the destination node. The provided expressions are used to evaluate the gains of cooperative diversity compared to noncooperation in correlated lognormal channels, taking into account the spectral and energy efficiency of the protocols and the half-duplex or full-duplex capability of the relay. Our analysis demonstrates that correlation and lognormal variances play a significant role on the performance gain of cooperative diversity against noncooperation.

  10. A unified simulation approach for the fast outage capacity evaluation over generalized fading channels

    KAUST Repository

    Rached, Nadhir B.

    2015-06-14

    The outage capacity (OC) is among the most important performance metrics of communication systems over fading channels. The evaluation of the OC, when Equal Gain Combining (EGC) or Maximum Ratio Combining (MRC) diversity techniques are employed, boils down to computing the Cumulative Distribution Function (CDF) of the sum of channel envelopes (equivalently amplitudes) for EGC or channel gain (equivalently squared enveloped/amplitudes) for MRC. Closed-form expressions of the CDF of the sum of many generalized fading variates are generally unknown and constitute open problems. In this paper, we develop a unified hazard rate twisting Importance Sampling (IS) based approach to efficiently estimate the CDF of the sum of independent arbitrary variates. The proposed IS estimator is shown to achieve an asymptotic optimality criterion, which clearly guarantees its efficiency. Some selected simulation results are also shown to illustrate the substantial computational gain achieved by the proposed IS scheme over crude Monte-Carlo simulations.

  11. Evaluation of allowed outage times (AOTs) from a risk and reliability standpoint

    Energy Technology Data Exchange (ETDEWEB)

    Vesely, W.E. (Science Applications International Corp., Columbus, OH (USA))

    1989-08-01

    This report describes the basic risks which are associated with allowed outage times (AOTs), defines strategies for selecting the risks to be quantified, and describes how the risks can be quantified. The report furthermore describes criteria considerations in determining the acceptability of calculated AOT risks, and discusses the merits of relative risk criteria versus absolute risk criteria. The detailed evaluations which are involved in calculating AOT risks, including uncertainty considerations are also discussed. The report also describes the proper ways that risks from multiple AOTs should be considered so that risks are properly accumulated from proposed multiple AOT changes, but are not double-counted. Generally, average AOT risks which include the frequency of occurrence of the AOT need to be accumulated but single downtime risks don't since they apply to individual AOTs. 8 refs., 22 tabs.

  12. Global NDE Best Practice for Technology Improvement, Outage Management, Foreign Material Exclusion and Dose Control

    Energy Technology Data Exchange (ETDEWEB)

    Glass, S. W.; Mohr, F.

    2010-07-01

    Non Destructive Examination (NDE) is a critical element of both Boiling Water and Pressurized Water Reactor outages. Frequently this includes critical path activity so both the utility and the inspection vendor are under intense pressure to perform the work quickly. Concurrent with AREVA's new global organization of NDE resources, AREVA NDE SOLUTIONS, efforts have intensified for global application of lessons learned and best practices. These best practices include new developments as well as continuous improvements to well established tools and NDE techniques. Advancements range from steam generator robots, advanced steam generator deposit characterization sensors and method, new phased array approaches for PWR and BWR reactor vessel examination, new sensors and approaches for RPV head examinations, plus advanced internals examination robots and methods. In addition to specialized tools and techniques, best practice includes numerous management innovations. AREVA's multi-disciplined integrated nuclear worker strategy helps to minimize the total number of personnel deployed to multi-task outages. Specific design and on-site practice has been implemented to minimize or eliminate foreign material from the reactor system and vigorous pursuit of dose management practices keeps our nuclear worker dose as low as reasonably achievable. The industry is moving to much more conservative nuclear worker dose limits. While this is proving to be an issue with many vendors, AREVA has had an internal policy of <2R since 2006. Globalizing the organization also helps AREVA manage peaks and unplanned emergency inspections from an enlarged pool of globally qualified inspection personnel and tools. (Author)

  13. Unified Importance Sampling Schemes for Efficient Simulation of Outage Capacity over Generalized Fading Channels

    KAUST Repository

    Rached, Nadhir B.

    2015-11-13

    The outage capacity (OC) is among the most important performance metrics of communication systems operating over fading channels. Of interest in the present paper is the evaluation of the OC at the output of the Equal Gain Combining (EGC) and the Maximum Ratio Combining (MRC) receivers. In this case, it can be seen that this problem turns out to be that of computing the Cumulative Distribution Function (CDF) for the sum of independent random variables. Since finding a closedform expression for the CDF of the sum distribution is out of reach for a wide class of commonly used distributions, methods based on Monte Carlo (MC) simulations take pride of price. In order to allow for the estimation of the operating range of small outage probabilities, it is of paramount importance to develop fast and efficient estimation methods as naive Monte Carlo (MC) simulations would require high computational complexity. In this line, we propose in this work two unified, yet efficient, hazard rate twisting Importance Sampling (IS) based approaches that efficiently estimate the OC of MRC or EGC diversity techniques over generalized independent fading channels. The first estimator is shown to possess the asymptotic optimality criterion and applies for arbitrary fading models, whereas the second one achieves the well-desired bounded relative error property for the majority of the well-known fading variates. Moreover, the second estimator is shown to achieve the asymptotic optimality property under the particular Log-normal environment. Some selected simulation results are finally provided in order to illustrate the substantial computational gain achieved by the proposed IS schemes over naive MC simulations.

  14. Duration of load revisited

    DEFF Research Database (Denmark)

    Hoffmeyer, Preben; Sørensen, John Dalsgaard

    2007-01-01

    were formed. Four groups were subjected to short-term strength tests, and four groups were subjected to long-term tests. Creep and time to failure were moni-tored. Time to failure as a function of stress level was established and the reliability of stress level assessment was discussed. A significant...... mechanosorptive effect was demonstrated both in terms of increased creep and shortening of time to failure. The test results were employed for the calibration of four existing duration of load models. The effect of long-term loading was expressed as the stress level SL50 to cause failure after 50 years of loading...... and of the short-term and long-term strengths. For permanent and imposed library loads, reliability-based estimation of the load duration factor gave almost the same results as direct, deterministic calibration. Keywords: Creep, damage models, duration of load, equal rank assumption, load duration factor, matched...

  15. A guidance law for UAV autonomous aerial refueling based on the iterative computation method

    Directory of Open Access Journals (Sweden)

    Luo Delin

    2014-08-01

    Full Text Available The rendezvous and formation problem is a significant part for the unmanned aerial vehicle (UAV autonomous aerial refueling (AAR technique. It can be divided into two major phases: the long-range guidance phase and the formation phase. In this paper, an iterative computation guidance law (ICGL is proposed to compute a series of state variables to get the solution of a control variable for a UAV conducting rendezvous with a tanker in AAR. The proposed method can make the control variable converge to zero when the tanker and the UAV receiver come to a formation flight eventually. For the long-range guidance phase, the ICGL divides it into two sub-phases: the correction sub-phase and the guidance sub-phase. The two sub-phases share the same iterative process. As for the formation phase, a velocity coordinate system is created by which control accelerations are designed to make the speed of the UAV consistent with that of the tanker. The simulation results demonstrate that the proposed ICGL is effective and robust against wind disturbance.

  16. A guidance law for UAV autonomous aerial refueling based on the iterative computation method

    Institute of Scientific and Technical Information of China (English)

    Luo Delin; Xie Rongzeng; Duan Haibin

    2014-01-01

    The rendezvous and formation problem is a significant part for the unmanned aerial vehicle (UAV) autonomous aerial refueling (AAR) technique. It can be divided into two major phases: the long-range guidance phase and the formation phase. In this paper, an iterative computation guidance law (ICGL) is proposed to compute a series of state variables to get the solu-tion of a control variable for a UAV conducting rendezvous with a tanker in AAR. The proposed method can make the control variable converge to zero when the tanker and the UAV receiver come to a formation flight eventually. For the long-range guidance phase, the ICGL divides it into two sub-phases: the correction sub-phase and the guidance sub-phase. The two sub-phases share the same iterative process. As for the formation phase, a velocity coordinate system is created by which control accelerations are designed to make the speed of the UAV consistent with that of the tanker. The simulation results demonstrate that the proposed ICGL is effective and robust against wind disturbance.

  17. Experimental studies on temperature rise within a hydrogen cylinder during refueling

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yan-Lei; Zhao, Yong-Zhi; Zhao, Lei; Li, Xiang; Chen, Hong-gang; Zheng, Jin-Yang [Institute of Process Equipment, Zhejiang University, Hangzhou 310027 (China); Zhang, Li-Fang; Zhao, Hui; Sheng, Run-Hua; Xie, Tian; Hu, Dong-Hao [Beijing Feichi Lvneng Power Sources Corporation, Beijing 100094 (China)

    2010-04-15

    In this research, experiments were performed to investigate the thermal behaviors such as temperature rise and distributions inside 35 MPa, 150 L hydrogen storage cylinders during its refueling. The main factors affecting the temperature rise in the fast fill process such as the mass filling rate and initial pressure in the cylinder were considered. The experimental results show that the mass filling rate is a constant when the ratio of the pressure in the tank to the cylinder is higher than 1.7, and the mass filling rate decreases when the ratio is lower than 1.7; the temperature inside the cylinder increases nonlinearly in the filling process and the maximum value of temperature rise at the interface of the cylinder exists in the caudal region; the temperature rise reaches a larger value with a lower initial pressure in the cylinder or a higher mass filling rate. Furthermore, the limit of mass filling rate in the case of different ambient temperature was obtained. (author)

  18. Behavioral response to hydrogen fuel cell vehicles and refueling: Results of California drive clinics

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Elliot; Lidicker, Jeffrey R. [Transportation Sustainability Research Center (TSRC), University of California, Berkeley, 1301 S. 46th Street. Bldg 190, Richmond, CA 94804-4648 (United States); Shaheen, Susan A. [Transportation Sustainability Research Center (TSRC), University of California, Berkeley, 1301 S. 46th Street. Bldg 190, Richmond, CA 94804-4648 (United States); Institute of Transportation Studies, University of California, Davis (United States); Lipman, Timothy E. [Transportation Sustainability Research Center (TSRC), University of California, Berkeley, 2614 Dwight Way, MC 1782, Berkeley, CA 94720-1782 (United States)

    2009-10-15

    Over the last several decades, hydrogen fuel cell vehicles (FCVs) have emerged as a zero tailpipe-emission alternative to the battery electric vehicle (EV). To address questions about consumer reaction to FCVs, this report presents the results of a ''ride-and-drive'' clinic series (N = 182) held in 2007 with a Mercedes-Benz A-Class ''F-Cell'' hydrogen FCV. The clinic evaluated participant reactions to driving and riding in an FCV, as well as vehicle refueling. Pre-and post-clinic surveys assessed consumer response. More than 80% left with a positive overall impression of hydrogen. The majority expressed a willingness to travel 5-10 min to find a hydrogen station. More than 90% of participants would consider an FCV driving range of 300 miles (480 km) to be acceptable. Stated willingness-to-pay preferences were explored. The results show that short-term exposure can improve consumer perceptions of hydrogen performance and safety among people who are the more likely early adopters. (author)

  19. HyApproval - Handbook for the approval of hydrogen refuelling stations - First preliminary achievements

    Energy Technology Data Exchange (ETDEWEB)

    Wurster, R.; Vandendungen, G.; Guichard, J.; Molag, M.; Barron, J.; Reijalt, M.; Hill, H.J.; Landinger, H.

    2007-05-15

    The EU-funded project HyApproval [www.hyapproval.org] aims at developing a universal Handbook to facilitate the approval process of Hydrogen Refuelling Stations (HRS) in Europe. The main goal of the HyApproval partnership with 22 partners from Europe and one each from China, Japan and the USA is to provide a Handbook of technical and regulatory requirements to assist authorisation officials, companies and organisations in the safe implementation and operation of HRS. Achievements during the first 15 months: analyses of HRS technology concepts and of equipment and safety distances/ Intermediate Design Paper/ Regulations, Codes and Standards (RCS) review and comparison/ first Handbook draft and first review sessions with HySafe experts/ safety matrix/ identification of accident scenarios/ agreement on safety documentation/ critical review of reliability data from collections and risk studies/ risk assessment (RA) criteria definition and RA/ matrix of acceptability and awareness levels/ database of Fire Associations and First Responders/ calendar of hydrogen events/ general description of CGH{sub 2} interfaces. (au)

  20. U.S. - Canada Power System Outage Task Force : final report on the implementation of task force recommendations

    Energy Technology Data Exchange (ETDEWEB)

    Burpee, D.; Dabaghi, H.; Jackson, L.; Kwamena, F.; Richter, J.; Rusnov, T. [Natural Resources Canada, Ottawa, ON (Canada); Friedman, K.; Mansueti, L.; Meyer, D. [United States Dept. of Energy, Washington, DC (United States)

    2006-09-15

    The joint U.S. - Canada Power System Outage Task Force was created to investigate the cause of the largest power outage in North American history, with reference to when it began, when it was complete, how much electric load was affected, and why it was not contained. The August 2003 outage, which affected 50 million people, revealed the vulnerability of the North American electric system and raised questions regarding its management and operation. This report outlined all of the actions taken to prevent or minimize future blackouts and improve the security of the North American electric power grid. Recommendations were presented to minimize the potential for future outages. The Task Force examined the electric system, nuclear facilities and security. Potential remedial measures include mandatory reliability standards, development of an effective compliance system, and rationalization of the current system of reliability organizations. Since the blackout, mandatory reliability standards have been implemented in jurisdictions across Canada and in the United States. The North American Electric Reliability Council (NERC) played an important role in the Task Force's investigation of the outage. It approved a series of actions intended to improve the reliability of the North American bulk power system. The Final Blackout Report identified the causes of the blackout and included 46 recommendations on actions needed by government and industry, many of which include several elements. The recommendations were accepted and endorsed by the Task Force to improve grid reliability. This report presented each of the 46 recommendations as well as the actions taken in response to each recommendation. Recommendations 1 through 14 discussed institutional issues relates to reliability. Recommendations 15 to 31 covered supporting and strengthening NERC actions of February 10, 2004. Recommendations 32 through 44 covered the physical and cyber security of North American bulk power

  1. H2moves.eu Scandinavia. ''Experience from operating a 70 MPa hydrogen refuelling station in Oslo''. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sloth, M.

    2013-02-15

    As part of the H2MOVES Scandinavia project H2 Logic were to construct a large scale hydrogen refuelling station (HRS) in Oslo providing hydrogen for FCEV's from Daimler and Hyundai in the project. The effort has provided extensive results and lessons learned across the entire process from site selection, HRS design and manufacturing to the final installation and operation. An extensive site screening of more than 30 sites in Oslo was firstly conducted to identify the most optimal location for the HRS. A suitable site was identified at the research organisation SINTEF in Gaustad in the western part of Oslo. The location was strategically well located with regards to the other HRS's in the city ensuring good refuelling coverage in Oslo. The HRS was manufactured, installed and operated by H2 Logic based on the company's H2Station technology. The HRS provides 70MPa refuelling in accordance with the SAE J2601, and operation results have confirmed refuelling times consistently below four minutes for a full tank. The HRS includes onsite electrolysis production providing a 20kg/day base load supply, with potentially additional trucking-in of hydrogen up to a total capacity of 200kg/day. The installation of the HRS took in total 10 days, from arrival at site, until first refuelling was conducted. This included local inspection by third parties and authorities as well as several days of hydrogen production and compression to reach the necessary refuelling pressure. Before opening a refuelling recommendation process was successfully conducted by Daimler. The HRS opened on 21st November 2011 and has been operated for 13,5 months during the remainder project period (ending December 2012). The HRS is expected to continue operation beyond the project. Below are shown the major operation results from the HRS during the project: 1) 701 kg dispensed; 2) 313 refueling's conducted; 3) Average availability of 97% during first half of 2012; 4) 53% of all down

  2. 飞机压力加油仿真计算研究%Study on Simulation of Airplane Pressure Refueling System

    Institute of Scientific and Technical Information of China (English)

    王京; 鲁维

    2014-01-01

    对飞机地面压力加油系统进行了仿真计算研究,详细阐述了建模理论基础和方法,并以某型飞机为例进行了建模仿真,对全机加满油时间和管路的最大流速进行了计算。通过地面压力加油试验进行验证,压力加满油时间基本一致,本文的仿真计算为改进压力加油系统设计提供了参考。%The simulation study of the airplane pressure refueling system on the ground was launched in this paper. The methods and theories about model building were presented. Through the pressure refueling system model simulation, the refueling time and maximum flow velocity of pipeline were assessed. The simulation results were compared with pressure refueling test results, it showed that the refueling time of both were almost the same. This paper provides a method to improve the system design.

  3. Alcohol-fueled vehicles: An alternative fuels vehicle, emissions, and refueling infrastructure technology assessment

    Energy Technology Data Exchange (ETDEWEB)

    McCoy, G.A.; Kerstetter, J.; Lyons, J.K. [and others

    1993-06-01

    Interest in alternative motor vehicle fuels has grown tremendously over the last few years. The 1990 Clean Air Act Amendments, the National Energy Policy Act of 1992 and the California Clean Air Act are primarily responsible for this resurgence and have spurred both the motor fuels and vehicle manufacturing industries into action. For the first time, all three U.S. auto manufacturers are offering alternative fuel vehicles to the motoring public. At the same time, a small but growing alternative fuels refueling infrastructure is beginning to develop across the country. Although the recent growth in alternative motor fuels use is impressive, their market niche is still being defined. Environmental regulations, a key driver behind alternative fuel use, is forcing both car makers and the petroleum industry to clean up their products. As a result, alternative fuels no longer have a lock on the clean air market and will have to compete with conventional vehicles in meeting stringent future vehicle emission standards. The development of cleaner burning gasoline powered vehicles has signaled a shift in the marketing of alternative fuels. While they will continue to play a major part in the clean vehicle market, alternative fuels are increasingly recognized as a means to reduce oil imports. This new role is clearly defined in the National Energy Policy Act of 1992. The Act identifies alternative fuels as a key strategy for reducing imports of foreign oil and mandates their use for federal and state fleets, while reserving the right to require private and municipal fleet use as well.

  4. Micro-generation systems and electrolysers for refuelling private bi-fuel cars at home

    Energy Technology Data Exchange (ETDEWEB)

    Newborough, M. [ITM Power plc, Mill House, Royston Road, Wendens Ambo, Saffron Walden, Essex CB11 4JX (United Kingdom); Peacock, A.D. [The Energy Academy, Heriot Watt University, Riccarton, Edinburgh EH14 4AS (United Kingdom)

    2009-05-15

    An assessment is presented of the prospective use of micro-generation systems in conjunction with electrolysers and hydrogen stores for refuelling private bi-fuel (gasoline/hydrogen) cars with hydrogen. For a range of system sizes and three power source operating modes, predictions are made of the annual travel range on hydrogen and the associated CO{sub 2} savings. A basic system (Mode A) operating solely from the output of a photovoltaic array was found to generate sufficient hydrogen to allow a passenger vehicle with a fuel efficiency of 8.5 l/100 km (33 mpg) to travel 613 km annually per kW of PV installed. An alternative system (Mode B) that permitted network electricity to contribute to hydrogen production, provided that the CO{sub 2} emission factor of the generated hydrogen was half that of gasoline, enabled an annual travel distance of 772 km per kW of PV installed. A hybrid micro-generation system comprising a PV and micro-CHP system (Mode C), where the electricity that would otherwise be exported from the dwelling was diverted to hydrogen production, achieved a more consistent hydrogen production rate across the year. This resulted in a lower on-site storage requirement; when compared with Mode A, it provided an additional annual travel distance on hydrogen of between 1285 and 1833 km. A utility factor was employed to indicate the extent to which a system design could deliver a given daily driving distance on hydrogen across the year. High utility factors (>70%) were only achievable for modest daily driving distances (10-17 km) for the considered range of PV sizes (1.7-8.5 kW). (author)

  5. Fuzzy-based risk prioritization for a hydrogen refueling facility in Malaysia

    Institute of Scientific and Technical Information of China (English)

    Hue-yee CHONG; Mahidzal DAHARI; Hwa-jen YAP; Ying-tai LOONG

    2013-01-01

    Hydrogen is starting to be mentioned as an alternative fuel to replace the fossil fuel in future transportation applications due to its characteristics of zero greenhouse gas emission and high energy efficiency.Before hydrogen fuel and its facilities can be introduced to the public,relevant safety issues and its hazards must be assessed in order to avoid any chance of injury or loss.While a traditional risk assessment has difficulty in prioritizing the risk of failure modes,this paper proposes a new fuzzy-based risk evaluation technique which uses fuzzy value to prioritize the risk of various scenarios.In this study,the final risk of each failure modes was prioritized by using the MATLAB fuzzy logic tool box with a combination of two assessments.The first assessment was concerned with the criteria which affected the actual probability of occurrence.This assessment considered the availability of the standard that was applied to prevent the likelihood of the scenario occurring.On the other hand,the second assessment was focused on evaluating the consequence of the failure by taking into account the availability of detection and the complexity of the failure rather than only the severity of the scenarios.A total of 87 failure scenarios were identified using failure modes and effect analysis(FMEA)procedures on hydrogen refueling station models.Fuzzy-based assessments were performed through risk prioritizing various failure scenarios with a fuzzy value(0 to 1)and risk level(low,medium,and high)while a traditional risk assessment approach presented the risks only in forms of level(low,medium,and/or high).Availability of the fuzzy value enabled further prioritizing on the risk results that fell in the same level of risk.This study concluded that fuzzy-based risk evaluation is able to further prioritize the decisions when compared with a traditional risk assessment method.

  6. Automated refueling simulations of a CANDU for the exploitation of thorium fuels

    Science.gov (United States)

    Holmes, Bradford

    CANDU nuclear reactors are in a unique circumstance where they are able to utilize and exploit a number of different fuel options to provide power as a utility. Thorium, a fertile isotope found naturally, is one option that should be explored. Thorium is more abundant than uranium, which is the typical fuel in the reactor and the availability of thorium makes nuclear energy desirable to more countries. This document contains the culmination of a project that explores, tests, and analyzes the feasibility of using thorium in a CANDU reactor. The project first develops a set of twodimensional lattice and three dimensional control rod simulations using the DRAGON Version 4 nuclear physics codes. This step is repeated for many concentrations of thorium. The data generated in these steps is then used to determine a functional enrichment of thorium. This is done via a procedural elimination and optimization of certain key parameters including but not limited to average exit burnup and reactivity evolution. For the purposes of this project, an enrichment of 1 % thorium was found viable. Full core calculations were done using the DONJON 4 code. CANFUEL, a program which simulates the refueling operations of a CANDU reactor for this fuel type was developed and ran for a simulation period of one hundred days. The program and the fuel selection met all selected requirements for the entirety of the simulation period. CANFUEL requires optimization for fuel selection before it can be used extensively. The fuel selection was further scrutinized when a reactivity insertion event was simulated. The adjuster rod 11 withdrawal from the core was analyzed and compared to classical CANDU results in order to ensure no significant deviations or unwanted evolutions were encountered. For this case, the simulation results were deemed acceptable with no significant deviations from the classical CANDU case.

  7. Duration Calculus: Logical Foundations

    DEFF Research Database (Denmark)

    Hansen, Michael Reichhardt; Chaochen, Zhou

    1997-01-01

    The Duration Calculus (abbreviated DC) represents a logical approach to formal design of real-time systems, where real numbers are used to model time and Boolean valued functions over time are used to model states and events of real-time systems. Since it introduction, DC has been applied to many...

  8. The Duration of Development

    NARCIS (Netherlands)

    J. Tinbergen (Jan)

    1995-01-01

    textabstractThe author considers the problem of the duration of development and its consequences for development assistance, in the developing as well as developed countries. Emphasis is given to the influence of development aid and it is argued that the time dimension has important policy implicati

  9. Outage Key Safety Functions Configuration risk assessment for a three loops Westinghouse PWR

    Energy Technology Data Exchange (ETDEWEB)

    Cid, M.M.; Dies, J., E-mail: javier.Dies@Upc.Edu; Tapia, C., E-mail: carlos.Tapia@Upc.Edu; Diaz, P., E-mail: pedro.diaz.bayona@upc.edu

    2015-09-15

    Highlights: • The paper evaluates the use of PSA on the Outage configuration risk management. • A method is proposed based on Risk Criteria to evaluate the OKSFs’ Configurations. • The methodology allows to identify which of the OKSFs can be analyzed using PSA. • The method has been applied to a Pilot real case. The OKSFs procedure is evaluated. - Abstract: The methodology developed provides guidance on the use of Probabilistic Safety Assessment (PSA) for the risk-informed evaluation of Guides which ensure the compliment of Outage Key Safety Functions (OKSFs) in Nuclear Power Plants. The methodology has been applied to the 3rd and 13th Plant Operational States (POSs) as a pilot experience. These POSs are within the Operating Mode 4 (Hot Shutdown) of a three loops Westinghouse Pressurized Water Reactor. The addressed Guide requires the operability of just one charge pump as boric acid supply source. PSA gives a Core Damage Frequency increase (ΔCDF) of 1.19 × 10{sup −6} year{sup −1} for the unavailability of the charge pump in standby, consequently, the maximum exposure time (time for the Increase of Core Damage Probability of the configuration to reach 1.0E−06) for this situation is T = 53.6 h. Given an average time for the POSs of 40 h, it is concluded that the charge pumps requirement is correct. However, it could be improved with the inclusion of an additional inventory replacement function. This would limit the effect on risk of the charge pump unavailability. Furthermore, the need for the external electrical sources to be available during Mode 4 is ratified. The procedure requires the operability of both supply sources during the POSs. The unavailability of one of supply sources them involves a ΔCDF equal to 1.64 × 10{sup −5} year{sup −1} and a maximum exposure time of T = 3.89 h. This requirement is considered appropriate from the risk-informed regulation point of view.

  10. Exact Outage Probability of Dual-Hop CSI-Assisted AF Relaying Over Nakagami-m Fading Channels

    KAUST Repository

    Xia, Minghua

    2012-10-01

    In this correspondence, considering dual-hop channel state information (CSI)-assisted amplify-and-forward (AF) relaying over Nakagami- m fading channels, the cumulative distribution function (CDF) of the end-to-end signal-to-noise ratio (SNR) is derived. In particular, when the fading shape factors m1 and m2 at consecutive hops take non-integer values, the bivariate H-function and G -function are exploited to obtain an exact analytical expression for the CDF. The obtained CDF is then applied to evaluate the outage performance of the system under study. The analytical results of outage probability coincide exactly with Monte-Carlo simulation results and outperform the previously reported upper bounds in the low and medium SNR regions.

  11. Building an alternative fuel refueling network: How many stations are needed and where should they be placed?

    Science.gov (United States)

    Nicholas, Michael Anselm

    Gasoline stations are so numerous that the fear of running out of fuel is likely not a top concern among drivers. This may not be the case with the introduction of a new alternative fuel such as hydrogen or electricity. The next three chapters, originally written as peer reviewed journal papers[1,2,3], examine the characteristics of refueling in today's gasoline network and compares these characteristics to hypothetical new alternative fuel networks. Together, they suggest that alternative fuel networks with many fewer stations than exist in the gasoline network could be acceptable to future consumers. This acceptability is measured in three ways. The first chapter examines the distance from home to the nearest station and finds that if alternative fuel stations were one-third as numerous as gasoline stations, the travel time to the nearest station was virtually identical to that of gasoline stations. The results suggest that even for station networks numbering only one-twentieth the current number of outlets, the difference in travel time with respect to gasoline is relatively small. Acceptability was examined in the second chapter by analyzing the spatial refueling patterns of gasoline. This reveals that the volume of fuel sold is greater around the highways and that the route from home to the nearest highway entrance may account for a large portion of refueling. This suggests that the first alternative fuel stations could be sited along the highway near entrances and could provide acceptable access to fuel for those who use these highway entrances to access the wider region. Subsequent stations could be sited closer to the homes of customers. The third chapter estimates acceptability, measured in terms of initial vehicle purchase price, of refueling away from one's own town. A pilot survey using a map-based questionnaire was distributed to 20 respondents. Respondents chose ten stations locations to enable their most important destinations. The alternative fuel

  12. On the sum of Gamma-Gamma variates with application to the fast outage probability evaluation over fading channels

    KAUST Repository

    Issaid, Chaouki Ben

    2017-04-01

    The Gamma-Gamma distribution has recently emerged in a number of applications ranging from modeling scattering and reverbation in sonar and radar systems to modeling atmospheric turbulence in wireless optical channels. In this respect, assessing the outage probability achieved by some diversity techniques over this kind of channels is of major practical importance. In many circumstances, this is intimately related to the difficult question of analyzing the statistics of a sum of Gamma-Gamma random variables. Answering this question is not a simple matter. This is essentially because outage probabilities encountered in practice are often very small, and hence the use of classical Monte Carlo methods is not a reasonable choice. This lies behind the main motivation of the present work. In particular, this paper proposes a new approach to estimate the left tail of the sum of independent and identically distributed Gamma-Gamma variates. More specifically, we propose a mean-shift importance sampling scheme that efficiently evaluates the outage probability of L-branch maximum ratio combining diversity receivers over Gamma-Gamma fading channels. The proposed estimator satisfies the well-known bounded relative error criterion. We show the accuracy and the efficiency of our approach compared to naive Monte Carlo via some selected numerical simulations.

  13. Outage Analysis of Train-to-Train Communication Model over Nakagami-m Channel in High-Speed Railway

    Directory of Open Access Journals (Sweden)

    Pengyu Liu

    2013-01-01

    Full Text Available This paper analyzes the end-to-end outage performance of high-speed-railway train-to-train communication model in high-speed railway over independent identical and nonidentical Nakagami-m channels. The train-to-train communication is inter-train communication without an aid of infrastructure (for base station. Source train uses trains on other rail tracks as relays to transmit signals to destination train on the same track. The mechanism of such communication among trains can be divided into three cases based on occurrence of possible-occurrence relay trains. We first present a new closed form for the sum of squared independent Nakagami-m variates and then derive an expression for the outage probability of the identical and non-identical Nakagami-m channels in three cases. In particular, the problem is improved by the proposed formulation that statistic for sum of squared Nakagami-m variates with identical m tends to be infinite. Numerical analysis indicates that the derived analytic results are reasonable and the outage performance is better over Nakagami-m channel in high-speed railway scenarios.

  14. From Multi-Keyholes to Measure of Correlation and Power Imbalance in MIMO Channels: Outage Capacity Analysis

    CERN Document Server

    Levin, George

    2008-01-01

    An information-theoretic analysis of a multi-keyhole channel, which includes a number of statistically independent keyholes with possibly different correlation matrices, is given. When the number of keyholes or/and the number of Tx/Rx antennas is large, there is an equivalent Rayleigh-fading channel such that the outage capacities of both channels are asymptotically equal. In the case of a large number of antennas and for a broad class of fading distributions, the outage capacity is shown to be asymptotically Gaussian in distribution, and compact, closed-form expressions for the mean and variance are given. Motivated by the asymptotic analysis, a simple, full-ordering scalar measure of spatial correlation and power imbalance in MIMO channels is introduced, which quantifies the negative impact of these two factors on the outage capacity in a simple and well-tractable way. It does not require the eigenvalue decomposition, and has the full-ordering property. The size-asymptotic results are used to prove Telatar'...

  15. On Secrecy Outage of Relay Selection in Underlay Cognitive Radio Networks over Nakagami-m Fading Channels

    KAUST Repository

    Lei, Hongjiang

    2017-10-02

    In this paper, the secrecy outage performance of an underlay cognitive decode-and-forward relay network over independent but not necessarily identical distributed (i.n.i.d) Nakagami-m fading channels is investigated, in which the secondary user transmitter communicates with the secondary destination via relays, and an eavesdropper attempts to overhear the information. Based on whether the channel state information (CSI) of the wiretap links is available or not, we analyze the secrecy outage performance with optimal relay selection (ORS) and suboptimal relay selection (SRS) schemes, and multiple relays combining scheme (MRC) scheme is considered for comparison purpose. The exact and asymptotic closed-form expressions for the secrecy outage probability with three different relay selection schemes are derived and verified by Monte-Carlo simulations. The numerical results illustrate that ORS scheme always outperforms SRS and MRC schemes, and SRS scheme is better than MRC scheme in the lower fading parameters scenario. Furthermore, through asymptotic analysis, we find that these three different schemes achieve the same secrecy diversity order, which is determined by the number of the relays, and the fading parameters of the links among the relays and the destination.

  16. Average BER and outage probability of the ground-to-train OWC link in turbulence with rain

    Science.gov (United States)

    Zhang, Yixin; Yang, Yanqiu; Hu, Beibei; Yu, Lin; Hu, Zheng-Da

    2017-09-01

    The bit-error rate (BER) and outage probability of optical wireless communication (OWC) link for the ground-to-train of the curved track in turbulence with rain is evaluated. Considering the re-modulation effects of raining fluctuation on optical signal modulated by turbulence, we set up the models of average BER and outage probability in the present of pointing errors, based on the double inverse Gaussian (IG) statistical distribution model. The numerical results indicate that, for the same covered track length, the larger curvature radius increases the outage probability and average BER. The performance of the OWC link in turbulence with rain is limited mainly by the rain rate and pointing errors which are induced by the beam wander and train vibration. The effect of the rain rate on the performance of the link is more severe than the atmospheric turbulence, but the fluctuation owing to the atmospheric turbulence affects the laser beam propagation more greatly than the skewness of the rain distribution. Besides, the turbulence-induced beam wander has a more significant impact on the system in heavier rain. We can choose the size of transmitting and receiving apertures and improve the shockproof performance of the tracks to optimize the communication performance of the system.

  17. Outage Performance Analysis of Relay Selection Schemes in Wireless Energy Harvesting Cooperative Networks over Non-Identical Rayleigh Fading Channels.

    Science.gov (United States)

    Do, Nhu Tri; Bao, Vo Nguyen Quoc; An, Beongku

    2016-02-26

    In this paper, we study relay selection in decode-and-forward wireless energy harvesting cooperative networks. In contrast to conventional cooperative networks, the relays harvest energy from the source's radio-frequency radiation and then use that energy to forward the source information. Considering power splitting receiver architecture used at relays to harvest energy, we are concerned with the performance of two popular relay selection schemes, namely, partial relay selection (PRS) scheme and optimal relay selection (ORS) scheme. In particular, we analyze the system performance in terms of outage probability (OP) over independent and non-identical (i.n.i.d.) Rayleigh fading channels. We derive the closed-form approximations for the system outage probabilities of both schemes and validate the analysis by the Monte-Carlo simulation. The numerical results provide comprehensive performance comparison between the PRS and ORS schemes and reveal the effect of wireless energy harvesting on the outage performances of both schemes. Additionally, we also show the advantages and drawbacks of the wireless energy harvesting cooperative networks and compare to the conventional cooperative networks.

  18. Intermediate report of MoReMo. Modelling resilience for maintenance and outage

    Energy Technology Data Exchange (ETDEWEB)

    Oedewald, P.; Macchi, L. (VTT Technical Research Centre of Finland (Finland)); Axelsson, C. (Ringhals AB, Vattenfall AB (Sweden)); Eitrheim, M.H.R. (Institute for Energy Technology (Norway))

    2012-02-15

    Resilience Engineering (RE) is a new approach to safety that helps organisations and individuals adapt to unforeseen events and long-term changes. Such an approach is needed by nuclear power plants (NPPs) as they face demanding modification projects, high staff turnover and increased pressures to maintain and improve safety. The goal of the Modelling Resilience for Maintenance and Outage (MoReMO) project is to develop and test models and methods to identify and analyse resilience in safety-critical activities in natural everyday settings. In 2011, we have applied four approaches in different case studies: Organisational Core Task modelling (OCT), Functional Resonance Analysis Method (FRAM), Efficiency Thoroughness Trade-Off (ETTO) analysis, and Work Practice and Culture Characterisation. The project has collected data through observations, interviews and document reviews at two NPPs. Together, the four approaches have provided valuable insights for understanding the rationale behind work practices, their effects on safety, and the support of flexibility and adaptability. In 2012, the MoReMO project will complete the data collection and integrate results on how resilience can be operationalized in practical safety management tools for the companies. (Author)

  19. Optimal PMU placement for maintaining full network observability during single outage of lines

    Directory of Open Access Journals (Sweden)

    Fariborz Haghighatdar fesharaki

    2011-05-01

    Full Text Available Nowadays, the optimal application of phasor measurement units (PMUs in power systems is increasing because of their advantages such as the capability for dynamical state estimation and improvements in the speed of control and protection systems. In this paper, a new method is presented using binary integer linear programming for the optimal placement of PMUs to guarantee full observability of a power system. Moreover, the problem of the optimal placement of these units in the case of a single line outage is investigated. In all of the investigations, the effect of zero-injection buses in the power system was considered. The ability of the proposed method in solving any of these problems was demonstrated by applying to the 14-, 30-, 39-, 57- and 118-bus IEEE standard systems, 42-bus transmission network of Esfahan Regional Electric and also two very large-scale systems with 2383 and 2746 buses. The simulation results verified the effective and appropriate performance of the proposed method in comparison with other methods.

  20. Cognitive Multiple-Antenna Network with Outage and Rate Margins at the Primary System

    DEFF Research Database (Denmark)

    Maham, Behrouz; Popovski, Petar

    2015-01-01

    In the common model for spectrum sharing, cognitive users can access the spectrum as long as the target performance in the legitimate primary system is not violated. In this paper, we consider a downlink primary multiple-inputsingle- output (MISO) system which operates under a controlled interfer......In the common model for spectrum sharing, cognitive users can access the spectrum as long as the target performance in the legitimate primary system is not violated. In this paper, we consider a downlink primary multiple-inputsingle- output (MISO) system which operates under a controlled...... interference from the downlink MISO cognitive radio, also called secondary system. We derive exact expressions for outage probability of the primary user under Rayleigh fading, when the primary system is exposed to interference from a secondary base station. We treat three different operating modes...... of the adaptive-rate transmit-beamforming primary system and the adaptive-rate transmit antenna-selection primary system. The analytical results are confirmed by simulations, in which we analyze the impact of different parameters, such as the number of antennas and the amount of the interference on the system...

  1. A study on assessment methodology of surveillance test interval and allowed outage time

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chang Hyun; You, Young Woo; Cho, Jae Seon; Huh, Chang Wook; Kim, Do Hyoung; Kim, Ju Youl; Kim, Yoon Ik; Yang, Hui Chang; Park, Kang Min [Seoul National Univ., Seoul (Korea, Republic of)

    1998-03-15

    The objectives of this study is the development of methodology by which assesses the optimization of Surveillance Test Internal(STI) and Allowed Outage Time(AOT) using PSA method that can supplement the current deterministic methods and the improvement of Korean nuclear power plant safety. In this study, the survey about the assessment methodologies, modelings and results performed by domestic and international researches are performed as the basic step before developing the assessment methodology of this study. The assessment methodology that supplement the revealed problems in many other studies is presented and the application of new methodology into the example system assures the feasibility of this method. The sensitivity analyses about the failure factors of the components are performed in the bases of the and AOT is quantified. And the reliability assessment methodology about the diesel generator is reviewed and applied to the PSA code. The qualitative assessment for the STI/AOR of RPS/ESFAS assured safety the most important system in the nuclear power plant are performed.

  2. Plasma Outages in Pulsed, High-Power RF Hydrogen Ion Sources

    Science.gov (United States)

    Stockli, Martin; Han, Baoxi; Murray, Syd; Pennisi, Terry; Piller, Chip; Santana, Manuel; Welton, Robert

    2011-04-01

    Pulsed, high-power RF ion sources are needed to produce copious amounts of negative H-ions for high-power accelerators with charge-changing injection schemes. When increasing the RF power, the plasma inductance changes the RF resonance, which drifts away from the low-power resonance. When the RF circuit is tuned to maximize the (pulsed) plasma power, the (off-resonance) power at the beginning of the pulse is reduced. If the induced electric fields fall below the breakdown strength of the hydrogen gas, the plasma fails to develop. This can be avoided with a compromise tune and/or by increasing the inductance of the resonant circuit. However, the breakdown strength of the hydrogen gas increases with time due to the gradual decrease of the electron-rich plasma impurities, which causes plasma outages after weeks of reliable operation. In this paper we discuss the success of different mitigations that were tested and implemented to overcome this fundamental problem of pulsed, high-power RF hydrogen ion sources.

  3. Method for Evaluation of Outage Probability on Random Access Channel in Mobile Communication Systems

    Science.gov (United States)

    Kollár, Martin

    2012-05-01

    In order to access the cell in all mobile communication technologies a so called random-access procedure is used. For example in GSM this is represented by sending the CHANNEL REQUEST message from Mobile Station (MS) to Base Transceiver Station (BTS) which is consequently forwarded as an CHANNEL REQUIRED message to the Base Station Controller (BSC). If the BTS decodes some noise on the Random Access Channel (RACH) as random access by mistake (so- called ‘phantom RACH') then it is a question of pure coincidence which èstablishment cause’ the BTS thinks to have recognized. A typical invalid channel access request or phantom RACH is characterized by an IMMEDIATE ASSIGNMENT procedure (assignment of an SDCCH or TCH) which is not followed by sending an ESTABLISH INDICATION from MS to BTS. In this paper a mathematical model for evaluation of the Power RACH Busy Threshold (RACHBT) in order to guaranty in advance determined outage probability on RACH is described and discussed as well. It focuses on Global System for Mobile Communications (GSM) however the obtained results can be generalized on remaining mobile technologies (ie WCDMA and LTE).

  4. Optimal Power Allocation for Fading Channels in Cognitive Radio Networks: Ergodic Capacity and Outage Capacity

    CERN Document Server

    Kang, Xin; Nallanathan, Arumugam; Garg, Hari Krishna; Zhang, Rui

    2008-01-01

    A cognitive radio network (CRN) is formed by either allowing the secondary users (SUs) in a secondary communication network (SCN) to opportunistically operate in the frequency bands originally allocated to a primary communication network (PCN) or by allowing SCN to coexist with the primary users (PUs) in PCN as long as the interference caused by SCN to each PU is properly regulated. In this paper, we consider the latter case, known as spectrum sharing, and study the optimal power allocation strategies to achieve the ergodic capacity and the outage capacity of the SU fading channel under different types of power constraints and fading channel models. In particular, besides the interference power constraint at PU, the transmit power constraint of SU is also considered. Since the transmit power and the interference power can be limited either by a peak or an average constraint, various combinations of power constraints are studied. It is shown that there is a capacity gain for SU under the average over the peak ...

  5. Outage and ser performance of spectrum sharing system with TAS/MRC

    KAUST Repository

    Khan, Fahd Ahmed

    2013-06-01

    Capacity of the secondary network degrades due to the interference constraint from the primary network. The secondary network capacity can be enhanced by means of spatial diversity, that can be achieved by adding multiple antennas on the terminals. In this paper, the performance of a multiple-input multiple-output (MIMO) secondary link with transmit antenna selection (TAS) at the transmitter and maximum ratio combining (MRC) at the receiver is analysed. A peak transmit power constraint is considered in addition to the interference power constraint. For a Rayleigh faded channel, closed-form expression for the outage probability of a MIMO cognitive system (MIMO-CS) with TAS/MRC is derived. In addition, closed-form expressions of the moment generating function and the symbol error rate are also obtained. The performance of this system is analyzed for asymptotic regimes and it is shown that TAS/MRC in a MIMO-CS achieves a generalized diversity order of nTnR, where nT and nR are the number of transmit and receive antennas, respectively. Numerical results are also presented to corroborate the derived analytical results. © 2013 IEEE.

  6. BER and Outage Probability Approximations for LMMSE Detectors on Correlated MIMO Channels

    CERN Document Server

    Kammoun, Abla; Hachem, Walid; Najim, Jamal

    2008-01-01

    This paper is devoted to the study of the performance of the Linear Minimum Mean-Square Error receiver for (receive) correlated Multiple-Input Multiple-Output systems. By the random matrix theory, it is well-known that the Signal-to-Noise Ratio (SNR) at the output of this receiver behaves asymptotically like a Gaussian random variable as the number of receive and transmit antennas converge to +$\\infty$ at the same rate. However, this approximation being inaccurate for the estimation of some performance metrics such as the Bit Error Rate and the outage probability, especially for small system dimensions, Li et al. proposed convincingly to assume that the SNR follows a generalized Gamma distribution which parameters are tuned by computing the first three asymptotic moments of the SNR. In this article, this technique is generalized to (receive) correlated channels, and closed-form expressions for the first three asymptotic moments of the SNR are provided. To obtain these results, a random matrix theory technique...

  7. Risk-Based Allowed Outage Time and Surveillance Test Interval Extensions for Angra 1

    Directory of Open Access Journals (Sweden)

    Sonia M. Orlando Gibelli

    2012-01-01

    Full Text Available In this work, Probabilistic Safety Assessment (PSA is used to evaluate Allowed Outage Times (AOT and Surveillance Test Intervals (STI extensions for three Angra 1 nuclear power plant safety systems. The interest in such an analysis lies on the fact that PSA comprises a risk-based tool for safety evaluation and has been increasingly applied to support both the regulatory and the operational decision-making processes. Regarding Angra 1, among other applications, PSA is meant to be an additional method that can be used by the utility to justify Technical Specification relaxation to the Brazilian regulatory body. The risk measure used in this work is the Core Damage Frequency, obtained from the Angra 1 Level 1 PSA study. AOT and STI extensions are evaluated for the Safety Injection, Service Water and Auxiliary Feedwater Systems using the SAPHIRE code. In order to compensate for the risk increase caused by the extensions, compensatory measures as (1 test of redundant train prior to entering maintenance and (2 staggered test strategy are proposed. Results have shown that the proposed AOT extensions are acceptable for two of the systems with the implementation of compensatory measures whereas STI extensions are acceptable for all three systems.

  8. Outages threaten competitiveness of utility companies; Systemausfaelle bedrohen Wettbewerbschancen von Energieversorgern

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, A. [Global Switch FM GmbH, Frankfurt (Germany)

    2003-11-03

    In terms of deregulation and growing competition increased customer orientation is decisive for utility companies. For today's energy suppliers, economic success depends to a great extent on services and presentation. This development made Customer Relationship Management (CRM) with the appropriate software solutions a significant instrument. Beside the strategic realization the software tools must work and business continuity is crucial. For utility companies a secure IT-housing is highly important. A special facility equipment provides protection against outages and secures lasting success. (orig.) [German] Im Zeichen von Deregulierung und verschaerftem Wettbewerb ist in der Enegiewirtschaft erhoehte Kundenorientierung gefragt. Energieversorger beziehen ihren Erfolg zum grossen Teil aus Serviceleistungen und dem Auftritt gegenueber dem Kunden. Diese Entwicklung hat Customer Relationship Management (CRM) und die zugehoerigen Softwareloesungen zu einem wichtigen Instrument werden lassen. Damit neben der stategischen Umsetzung auch die modernen Softwaretools funktionieren, muss ein kontinuierlicher Geschaeftsbetrieb gewaehrleistet sein. Eine sichere Unterbringung von Rechenzentren ist fuer Energieversorger zur Erhaltung ihrer Wettbewerbsfaehigkeit von enormer Wichtigkeit. IT-gerechte Gebaeudetechnik bietet Schutz vor Ausfaellen und sichert so dauerhaften Erfolg. (orig.)

  9. A study on assessment methodology of surveillance test interval and Allowed Outage Time

    Energy Technology Data Exchange (ETDEWEB)

    Che, Moo Seong; Cheong, Chang Hyeon; Ryu, Yeong Woo; Cho, Jae Seon; Heo, Chang Wook; Kim, Do Hyeong; Kim, Joo Yeol; Kim, Yun Ik; Yang, Hei Chang [Seoul National Univ., Seoul (Korea, Republic of)

    1997-07-15

    Objectives of this study is the development of methodology by which assesses the optimization of Surveillance Test Interval(STI) and Allowed Outage Time(AOT) using PSA method that can supplement the current deterministic methods and the improvement of Korean nuclear power plants safety. In the first year of this study, the survey about the assessment methodologies, modeling and results performed by domestic and international researches are performed as the basic step before developing the assessment methodology of this study. The assessment methodology that supplement the revealed problems in many other studies is presented and the application of new methodology into the example system assures the feasibility of this method. In the second year of this study, the sensitivity analyses about the failure factors of the components are performed in the bases of the assessment methodologies of the first study, the interaction modeling of the STI and AOT is quantified. And the reliability assessment methodology about the diesel generator is reviewed and applied to the PSA code.

  10. On the Efficient Simulation of Outage Probability in a Log-normal Fading Environment

    KAUST Repository

    Rached, Nadhir Ben

    2017-02-15

    The outage probability (OP) of the signal-to-interference-plus-noise ratio (SINR) is an important metric that is used to evaluate the performance of wireless systems. One difficulty toward assessing the OP is that, in realistic scenarios, closed-form expressions cannot be derived. This is for instance the case of the Log-normal environment, in which evaluating the OP of the SINR amounts to computing the probability that a sum of correlated Log-normal variates exceeds a given threshold. Since such a probability does not admit a closed-form expression, it has thus far been evaluated by several approximation techniques, the accuracies of which are not guaranteed in the region of small OPs. For these regions, simulation techniques based on variance reduction algorithms is a good alternative, being quick and highly accurate for estimating rare event probabilities. This constitutes the major motivation behind our work. More specifically, we propose a generalized hybrid importance sampling scheme, based on a combination of a mean shifting and a covariance matrix scaling, to evaluate the OP of the SINR in a Log-normal environment. We further our analysis by providing a detailed study of two particular cases. Finally, the performance of these techniques is performed both theoretically and through various simulation results.

  11. The Application of Phasor Measurement Units in Transmission Line Outage Detection Using Support Vector Machine

    Directory of Open Access Journals (Sweden)

    A. Y. Abdelaziz

    2013-07-01

    Full Text Available Many protection applications are based upon the Phasor Measurement Units (PMUs technology. Therefore, PMUs have been increasingly widespread throughout the power network, and there are several researches have been made to locate the PMUs for complete system observability. This paper introduces an important application of PMUs in power system protection which is the detection of single line outage. In addition, a detection of the out of service line is achieved depending on the variations of phase angles measured at the system buses where the PMUs are located. Hence, a protection scheme from unexpected overloading in the network that may lead to system collapse can be achieved. Such detections are based upon an artificial intelligence technique which is the support Vector Machine (SVM classification tool. To demonstrate the effectiveness of the proposed approach, the algorithm is tested using offline simulation for both the 14-bus IEEE and the 30-bus IEEE systems. Two different kernels of the SVM are tested to select the more appropriate one (i.e. polynomial and Radial Basis Function (RBF kernels are used.

  12. Duration of symptoms

    DEFF Research Database (Denmark)

    Hansen, Olfred; Larsen, Susanne; Bastholt, Lars

    2005-01-01

    PURPOSE: To study the relationship between the durations of symptoms before the start of radiotherapy and treatment outcome in Stage I-III glottic cancer. METHODS AND MATERIALS: From 1965 to 1997, 611 glottic cancer patients from the Southern Region of Denmark were treated with primary radiotherapy....... A total of 544 patients fulfilled the criteria for inclusion to the study (Stage I-III glottic cancer, a duration of symptoms less than or equal to 36 months, primary radiotherapy with at least 50 Gy and sufficient data for analysis). The total radiation dose ranged from 50.0 to 71.6 Gy in 22 to 42...... of symptoms was a significant factor (p symptoms was statistically...

  13. Lateral Dynamic Stability of Aerial Refueling Aircraft and Tanker Aircraft%空中加油受油机横侧动操稳特性研究

    Institute of Scientific and Technical Information of China (English)

    宋双杰; 张玉莲

    2011-01-01

    空中加油时,加油机的气动力和力矩对受油机的操纵影响较大.需对影响大小进行定量分析,得出确定结论.本文对受油机的横侧动稳定性及操纵性进行了研究,确定了作用在受油机上由加油机翼端涡场引起的气动力和力矩的大小,提出一种简化气动模型,并将导数形式的力和力矩用于线性运动方程.研究表明,受油机具有发散的振荡特性,且主要由倾斜和侧向移动组成;飞行员在飞行时可通过不断操纵副翼来控制发散模态,保持飞机稳定.%During the air refueling, the aerodynamic force and the vortex field of the refueling tanker aircraft would greatly affect the manipulation of the refueling aircraft, and it is important to study this impact. This paper studies the cross-lateral dynamic stability and controllability of the air refueling tanker aircraft. The aerodynamic force and the vortex field of the refueling tanker aircraft on the wing of the refueling aircraft are determined through a simplified aerodynamic model. These forces and moments are expressed in a derivative form to be applied in the linear equations of motion. It is shown that the aerial refueling tanker aircraft would experience a divergent oscillation, mainly composed of tilt and lateral movement. By the manipulation of ailerons to control the divergence continuous mode, the aircraft may keep stable. The results of the present paper may serve as a theoretical basis for action that can be taken for other types of manipulation and other types of refueling aircraft.

  14. Core and Refueling Design Studies for the Advanced High Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, David Eugene [ORNL; Ilas, Dan [ORNL; Varma, Venugopal Koikal [ORNL; Cisneros, Anselmo T [ORNL; Kelly, Ryan P [ORNL; Gehin, Jess C [ORNL

    2011-09-01

    The Advanced High Temperature Reactor (AHTR) is a design concept for a central generating station type [3400 MW(t)] fluoride-salt-cooled high-temperature reactor (FHR). The overall goal of the AHTR development program is to demonstrate the technical feasibility of FHRs as low-cost, large-size power producers while maintaining full passive safety. This report presents the current status of ongoing design studies of the core, in-vessel structures, and refueling options for the AHTR. The AHTR design remains at the notional level of maturity as important material, structural, neutronic, and hydraulic issues remain to be addressed. The present design space exploration, however, indicates that reasonable options exist for the AHTR core, primary heat transport path, and fuel cycle provided that materials and systems technologies develop as anticipated. An illustration of the current AHTR core, reactor vessel, and nearby structures is shown in Fig. ES1. The AHTR core design concept is based upon 252 hexagonal, plate fuel assemblies configured to form a roughly cylindrical core. The core has a fueled height of 5.5 m with 25 cm of reflector above and below the core. The fuel assembly hexagons are {approx}45 cm across the flats. Each fuel assembly contains 18 plates that are 23.9 cm wide and 2.55 cm thick. The reactor vessel has an exterior diameter of 10.48 m and a height of 17.7 m. A row of replaceable graphite reflector prismatic blocks surrounds the core radially. A more complete reactor configuration description is provided in Section 2 of this report. The AHTR core design space exploration was performed under a set of constraints. Only low enrichment (<20%) uranium fuel was considered. The coated particle fuel and matrix materials were derived from those being developed and demonstrated under the Department of Energy Office of Nuclear Energy (DOE-NE) advanced gas reactor program. The coated particle volumetric packing fraction was restricted to at most 40%. The pressure

  15. 自助加油顾客需求分析%Requirement Analysis of Self- assist Refueling Consumer

    Institute of Scientific and Technical Information of China (English)

    李宏

    2011-01-01

    Based on the analysis of questionnaire survey of Beijing gas station consumers, the self- assist re- fueling market is subdivided. And combining service marketing 7Ps combination theory, the advice for development of self- assist refueling business is proposed, which provide references for improving self- assist refueling business of domestic oil products company.%通过对北京地区加油站顾客就选择自助加油的原因、加油消费的习惯和对自助加油价格的评价等内容进行问卷调查分析,对自助加油市场进行细分,结合服务营销7PS组合理论,对开展自助加油业务提出了一些初步意见,对改善国内石油公司自助加油业务具有一定借鉴价值。

  16. LEO cooperative multi-spacecraft refueling mission optimization considering J2 perturbation and target's surplus propellant constraint

    Science.gov (United States)

    Zhao, Zhao; Zhang, Jin; Li, Hai-yang; Zhou, Jian-yong

    2017-01-01

    The optimization of an LEO cooperative multi-spacecraft refueling mission considering the J2 perturbation and target's surplus propellant constraint is studied in the paper. First, a mission scenario is introduced. One service spacecraft and several target spacecraft run on an LEO near-circular orbit, the service spacecraft rendezvouses with some service positions one by one, and target spacecraft transfer to corresponding service positions respectively. Each target spacecraft returns to its original position after obtaining required propellant and the service spacecraft returns to its original position after refueling all target spacecraft. Next, an optimization model of this mission is built. The service sequence, orbital transfer time, and service position are used as deign variables, whereas the propellant cost is used as the design objective. The J2 perturbation, time constraint and the target spacecraft's surplus propellant capability constraint are taken into account. Then, a hybrid two-level optimization approach is presented to solve the formulated mixed integer nonlinear programming (MINLP) problem. A hybrid-encoding genetic algorithm is adopted to seek the near optimal solution in the up-level optimization, while a linear relative dynamic equation considering the J2 perturbation is used to obtain the impulses of orbital transfer in the low-level optimization. Finally, the effectiveness of the proposed model and method is validated by numerical examples.

  17. Long duration flights management

    Science.gov (United States)

    Sosa-Sesma, Sergio; Letrenne, Gérard; Spel, Martin; Charbonnier, Jean-Marc

    Long duration flights (LDF) require a special management to take the best decisions in terms of ballast consumption and instant of separation. As a contrast to short duration flights, where meteorological conditions are relatively well known, for LDF we need to include the meteorological model accuracy in trajectory simulations. Dispersions on the fields of model (wind, temperature and IR fluxes) could make the mission incompatible with safety rules, authorized zones and others flight requirements. Last CNES developments for LDF act on three main axes: 1. Although ECMWF-NCEP forecast allows generating simulations from a 4D point (altitude, latitude, longitude and UT time), result is not statistical, it is determinist. To take into account model dispersion a meteorological NCEP data base was analyzed. A comparison between Analysis (AN) and Forecast (FC) for the same time frame had been done. Result obtained from this work allows implementing wind and temperature dispersions on balloon flight simulator. 2. For IR fluxes, NCEP does not provide ascending IR fluxes in AN mode but only in FC mode. To obtain the IR fluxes for each time frame, satellite images are used. A comparison between FC and satellites measurements had been done. Results obtained from this work allow implementing flux dispersions on balloon flight simulator. 3. An improved cartography containing a vast data base had been included in balloon flight simulator. Mixing these three points with balloon flight dynamics we have obtained two new tools for observing balloon evolution and risk, one of them is called ASTERISK (Statistic Tool for Evaluation of Risk) for calculations and the other one is called OBERISK (Observing Balloon Evolution and Risk) for visualization. Depending on the balloon type (super pressure, zero pressure or MIR) relevant information for the flight manager is different. The goal is to take the best decision according to the global situation to obtain the largest flight duration with

  18. Understanding the design and economics of distributed tri-generation systems for home and neighborhood refueling-Part II: Neighborhood system case studies

    Science.gov (United States)

    Li, Xuping; Ogden, Joan M.

    2012-01-01

    The lack of a hydrogen infrastructure remains a major barrier for fuel cell vehicle (FCV) adoption. The high cost of an extensive hydrogen station network and the low utilization in the near term discourage private investment. Past experience of fuel infrastructure development for motor vehicles, indicates that innovative, distributed, small-volume hydrogen refueling methods may be required to refuel FCVs in the near term. Among small-volume refueling methods, home and neighborhood tri-generation systems stand out because the technology is available and has potential to alleviate consumer's fuel availability concerns. Additionally, it has features attractive to consumers such as convenience and security to refuel at home or in their neighborhood. In this paper, we study neighborhood tri-generation systems in multi-unit dwellings such as apartment complexes. We apply analytical tools including an interdisciplinary framework and an engineering/economic model to a representative multi-family residence in the Northern California area. The simulation results indicate that a neighborhood tri-generation system improves the economics of providing the three energy products for the households compared with the two alternatives studied. The small capacity of the systems and the valuable co-products help address the low utilization problem of hydrogen infrastructure.

  19. Rapid changes in the size of different functional organ and muscle groups during refueling in a long-distance migrating shorebird

    NARCIS (Netherlands)

    Piersma, T; Gudmundsson, GA; Lilliendahl, K; Gudmundsson, Gudmundur A.

    1999-01-01

    The adaptive value of size changes in different organ and muscle groups was studied in red knots (Calidris canutus islandica) in relation to their migration. Birds were sampled on five occasions: at arrival in Iceland in May 1994, two times during subsequent refueling, at departure toward, and on

  20. Characteristics of health IT outage and suggested risk management strategies: an analysis of historical incident reports in China.

    Science.gov (United States)

    Lei, Jianbo; Guan, Pengcheng; Gao, Kaihua; Lu, Xueqin; Chen, Yunan; Li, Yuefeng; Meng, Qun; Zhang, Jiajie; Sittig, Dean F; Zheng, Kai

    2014-02-01

    The healthcare industry has become increasingly dependent on using information technology (IT) to manage its daily operations. Unexpected downtime of health IT systems could therefore wreak havoc and result in catastrophic consequences. Little is known, however, regarding the nature of failures of health IT. To analyze historical health IT outage incidents as a means to better understand health IT vulnerabilities and inform more effective prevention and emergency response strategies. We studied news articles and incident reports publicly available on the internet describing health IT outage events that occurred in China. The data were qualitatively analyzed using a deductive grounded theory approach based on a synthesized IT risk model developed in the domain of information systems. A total of 116 distinct health IT incidents were identified. A majority of them (69.8%) occurred in the morning; over 50% caused disruptions to the patient registration and payment collection functions of the affected healthcare facilities. The outpatient practices in tertiary hospitals seem to be particularly vulnerable to IT failures. Software defects and overcapacity issues, followed by malfunctioning hardware, were among the principal causes. Unexpected health IT downtime occurs more and more often with the widespread adoption of electronic systems in healthcare. Risk identification and risk assessments are essential steps to developing preventive measures. Equally important is institutionalization of contingency plans as our data show that not all failures of health IT can be predicted and thus effectively prevented. The results of this study also suggest significant future work is needed to systematize the reporting of health IT outage incidents in order to promote transparency and accountability. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  1. Ensuring safety of fuel cell applications and hydrogen refuelling. Legislation and standards; Polttokennosovellusten ja vetytankkauksen turvallisuuden varmistaminen. Saeaedoeksiae ja standardeja

    Energy Technology Data Exchange (ETDEWEB)

    Nissila, M.; Sarsama, J.

    2013-09-15

    Fuel cell technology is considered a promising alternative in terms of viable energy systems. The advantages of fuel cell systems include a good efficiency rate and the lack of harmful environmental emissions. Factors which may slow down the commercialisation of fuel cell technology, e.g. fuel cell vehicles, include the high price of hydrogen and the insufficiency of the infrastructure required for the distribution of hydrogen. A large proportion of major car manufacturers are committed to introducing fuel cell cars to the market by 2014-2016. In order to ensure a successful market introduction of fuel cell vehicles, this has to be aligned with the development of the necessary hydrogen infrastructure. In the early commercialisation stages of a new technology, it is important to give the public correct, justified and understandable information on the safety of the fuel cell applications, and also on the measures taken to ensure the safety of applications. A lack of necessary information, inaccurate perceptions and prejudices can have an adverse effect on the public acceptance of fuel cell applications. Hazards and potential accidents related to fuel cell systems are mainly associated with the flammable substances (e.g. hydrogen, methane) used as fuel, the high pressure of hydrogen, electrical hazards, and dangers concerning technical systems in general. The fuel cell applications reviewed in this publication are transport applications and stationary applications and the refuelling system of gaseous hydrogen. The publication concentrates on fuel cells using hydrogen as fuel. The publication gives an overview of how EU-legislation (mainly various directives) and Finnish legislation applies to fuel cell systems and applications, and what kind of safety requirements the legislation sets. In addition, a brief overview of safety standards concerning fuel cell systems and hydrogen refuelling is presented. (orig.)

  2. HOSPITAL "LARGE-SCALE POWER OUTAGES," SCENARIO DESIGN AND COUNTERMEASURES%医院"大范围停电"情景构建及对策研究

    Institute of Scientific and Technical Information of China (English)

    程勇; 蔡建强; 王兴宇; 胡建华

    2015-01-01

    文章介绍了中国医学科学院肿瘤医院的供电系统概况;针对发生大范围停电的几种可能性,制订了针对四种情况的处置方法;列举了应对"大范围停电"需要准备的物资;阐述了针对"大范围停电"情景演练的意义.%The article briefly introduces the power supply system of Chinese Academy of Medical Sciences Cancer Hospital; developed disposal measures for the four possibilities for large-scale power outage; listed materials need to prepare for the "large-scale power outages"; elaborated the significance of the "large-scale power outages" dril.

  3. Duration judgements over multiple elements

    Directory of Open Access Journals (Sweden)

    Inci eAyhan

    2012-11-01

    Full Text Available We investigated the limits of the number of events observers can simultaneously time. For single targets occurring in one of eight positions sensitivity to duration was improved for spatially pre-cued items as compared to post-cued items indicating that exogenous driven attention can improve duration discrimination. Sensitivity to duration for pre-cued items was also marginally better for single items as compared to eight items indicating that even after the allocation of focal attention, distracter items can interfere with the encoding of duration. For an eight item array discrimination was worse for post-cued locations as compared to pre-cued locations indicating both that attention can improve duration discrimination performance and that it was not possible to access a perfect memory trace of the duration of eight elements. The interference from the distracters in the pre-cued eight item array may reflect some mandatory averaging of target and distracter events. To further explore duration averaging we asked subjects to explicitly compare average durations of multiple item arrays against a single item standard duration. Duration discrimination thresholds were significantly lower for single elements as compared to multiple elements, showing that averaging, either automatically or intentionally, impairs duration discrimination. There was no set size effect. Performance was the same for averages of two and eight items, but performance with even an average of two items was worse than for one item. This was also true for sequential presentation indicating poor performance was not due to limits on the division of attention across items. Rather performance appears to be limited by an inability to remember or aggregate duration information from two or more items. Although it is possible to manipulate perceived duration locally, there appears to be no perceptual mechanisms for aggregating local durations across space.

  4. High-Rate Communications Outage Recorder Operations for Optimal Payload and Science Telemetry Management Onboard the International Space Station

    Science.gov (United States)

    Shell, Michael T.; McElyea, Richard M. (Technical Monitor)

    2002-01-01

    All International Space Station (ISS) Ku-band telemetry transmits through the High-Rate Communications Outage Recorder (HCOR). The HCOR provides the recording and playback capability for all payload, science, and International Partner data streams transmitting through NASA's Ku-band antenna system. The HCOR is a solid-state memory recorder that provides recording capability to record all eight ISS high-rate data during ISS Loss-of-Signal periods. NASA payloads in the Destiny module are prime users of the HCOR; however, NASDA and ESA will also utilize the HCOR for data capture and playback of their high data rate links from the Kibo and Columbus modules. Marshall Space Flight Center's Payload Operations Integration Center manages the HCOR for nominal functions, including system configurations and playback operations. The purpose of this paper is to present the nominal operations plan for the HCOR and the plans for handling contingency operations affecting payload operations. In addition, the paper will address HCOR operation limitations and the expected effects on payload operations. The HCOR is manifested for ISS delivery on flight 9A with the HCOR backup manifested on flight 11A. The HCOR replaces the Medium-Rate Communications Outage Recorder (MCOR), which has supported payloads since flight 5A.1.

  5. Study of electrical power facilities and measures for planned outages in Japanese hemodialysis clinics after the Great East Japan Earthquake.

    Science.gov (United States)

    Ishida, Kai; Sawa, Manami; Fujiwara, Kousaku; Hirose, Minoru; Tsuruta, Harukazu; Takeuchi, Akihiro; Ikeda, Noriaki

    2013-02-01

    The Great East Japan Earthquake on 11 March 2011 caused major damage in northeastern Japan. The Kanto region experienced a massive electrical power shortage in the summer of 2011. A questionnaire was submitted to 354 hemodialysis clinics in Kanagawa prefecture and the Tokyo metropolitan area, excluding isolated islands, and 176 responses were analyzed (49.7%). The questions included evaluation of the availability of a private electricity generator, countermeasures in case of a planned outage, awareness of saving electricity, and improvement of safety of medical devices or electrical facilities after the earthquake. Only 12% of the clinics had private electricity generators and many clinics had no plans to introduce this facility. However, 96% of the clinics had established countermeasures to deal with a planned outage. Many clinics planned to provide dialysis on a different day or at a different time. All clinics had tried hard to establish procedures to save electricity in the summer of 2011, and 84% of the clinics had reconsidered and improved the safety of medical devices or electricity facilities after the earthquake. These results show that the awareness of crisis management was greatly improved in the wake of the earthquake.

  6. Power Control and Performance Analysis of Outage-Limited Cellular Network with MUD-SIC and Macro-Diversity

    CERN Document Server

    Ng, Derrick Wing Kwan

    2010-01-01

    In this paper, we analyze the uplink goodput (bits/sec/Hz successfully decoded) and per-user packet outage in a cellular network using multi-user detection with successive interference cancellation (MUD-SIC). We consider non-ergodic fading channels where microscopic fading channel information is not available at the transmitters. As a result, packet outage occurs whenever the data rate of packet transmissions exceeds the instantaneous mutual information even if powerful channel coding is applied for protection. We are interested to study the role of macro-diversity (MDiv) between multiple base stations on the MUD-SIC performance where the effect of potential error-propagation during the SIC processing is taken into account. While the jointly optimal power and decoding order in the MUD-SIC are NP hard problem, we derive a simple on/off power control and asymptotically optimal decoding order with respect to the transmit power. Based on the information theoretical framework, we derive the closed-form expressions...

  7. Exact closed form expressions for outage probability of GSC receivers over Rayleigh fading channel subject to self-interference

    KAUST Repository

    Nam, Sungsik

    2010-11-01

    Previous work on performance analyses of generalized selection combining (GSC) RAKE receivers based on the signal to noise ratio focused on the development of methodologies to derive exact closed-form expressions for various performance measures. However, some open problems related to the performance evaluation of GSC RAKE receivers still remain to be solved such that an assessment of the impact of self-interference on the performance of GSC RAKE receivers. To have a full and exact understanding of the performance of GSC RAKE receivers, the outage probability of GSC RAKE receivers needs to be analyzed as closed-form expressions. The major difficulty in this problem is to derive some joint statistics of ordered exponential variates. With this motivation in mind, we capitalize in this paper on some new order statistics results to derive exact closed-form expressions for outage probability of GSC RAKE receivers subject to self-interference over independent and identically distributed Rayleigh fading channels. © 2010 IEEE.

  8. Cooperative AF Relaying in Spectrum-Sharing Systems: Outage Probability Analysis under Co-Channel Interferences and Relay Selection

    KAUST Repository

    Xia, Minghua

    2012-11-01

    For cooperative amplify-and-forward (AF) relaying in spectrum-sharing wireless systems, secondary users share spectrum resources originally licensed to primary users to communicate with each other and, thus, the transmit power of secondary transmitters is strictly limited by the tolerable interference powers at primary receivers. Furthermore, the received signals at a relay and at a secondary receiver are inevitably interfered by the signals from primary transmitters. These co-channel interferences (CCIs) from concurrent primary transmission can significantly degrade the performance of secondary transmission. This paper studies the effect of CCIs on outage probability of the secondary link in a spectrum-sharing environment. In particular, in order to compensate the performance loss due to CCIs, the transmit powers of a secondary transmitter and its relaying node are respectively optimized with respect to both the tolerable interference powers at the primary receivers and the CCIs from the primary transmitters. Moreover, when multiple relays are available, the technique of opportunistic relay selection is exploited to further improve system performance with low implementation complexity. By analyzing lower and upper bounds on the outage probability of the secondary system, this study reveals that it is the tolerable interference powers at primary receivers that dominate the system performance, rather than the CCIs from primary transmitters. System designers will benefit from this result in planning and designing next-generation broadband spectrum-sharing systems.

  9. Operational readiness verification, phase 1: A study on safety during outage and restart of nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Hollnagel, E. [Linkoeping Univ. (Sweden). Dept. of Computer and Information Science; Gauthereau, V. [Linkoeping Univ. (Sweden). Dept. of Industrial Engineering

    2001-06-01

    This report contains the findings from the first phase of a study on safety during outage and restart of nuclear power plants. Operational Readiness Verification (ORV) - in Swedish called Driftklarhetsverifiering (DKV) - refers to the test and verification activities that are necessary to ensure that plant systems are able to provide their required functions when needed - more concretely that all plant systems are in their correct functional state when the plant is restarted after an outage period. The concrete background for this work is that nine ORV related incidents were reported in Sweden between July 1995 and October 1998. The work reported here comprised a literature survey of research relevant for ORV issues, and an assessment of the present situation at Swedish NPPs with respect to ORV. The literature survey was primarily aimed at research related to NPPs, but also looked at domains where similar problems have occurred, such as maintenance in commercial aviation. The survey looked specifically for organisational and MTO aspects relevant to the present situation in Swedish NPPs. One finding was that ORV should be seen as an integral part of maintenance, rather than as a separate activity. Another, that there is a characteristic distribution of error modes for maintenance and ORV, with many sequence errors and omissions, rather than a set of unique error modes. An international study further showed that there are important differences in how procedures are used, and in the balance between decentralisation and centralisation. Several studies also suggested that ORV could usefully be described as a barrier system in relation to the flow of work, for instance using the following five stages: (1) preventive actions during maintenance/outage, (2) post-test after completion of work, (3) pre-test before start-up, (4) the start-up sequence itself, and (5) preventive actions during power operation - possibly including automatic safety systems. In the field survey

  10. Final Environmental Impact Statement. Second KC-135R Air Refueling Squadron, Malmstrom Air Force Base, Montana

    Science.gov (United States)

    1989-07-01

    Short-duration socioeconomic impacts would he high and significant because the large number of construction-related inmigration has the potential of...not significant because of the following findings: o Although the 116 additional students are projected to accompany inmigrating operations-period...little in either Great Falls or Cascade County. I Although the County Jail is currently overcrowded, the relatively small number of military inmigrants

  11. 加油锥套远距图像的Hough-LS快速检测%Hough-LS Rapid Detection for Long-distance Refueling Drogue Image

    Institute of Scientific and Technical Information of China (English)

    杨博文; 孙永荣; 黄斌; 王勇; 刘建业

    2015-01-01

    在视觉辅助软管式空中加油系统中,如何在实时图像序列中将加油锥套从复杂背景环境中快速分离出来,对锥套进行快速检测与识别,是一个亟需解决的问题。论文针对加油锥套远距图像目标检测与定位问题,提出了一种基于形状信息的Hough-LS两级锥套目标检测与定位方法。文中首先采用快速霍夫梯度法(FHGM)进行加油锥套预检测,而后利用中心八向搜索法进行锥套边缘提取,最后基于最小二乘椭圆拟合实现加油锥套远距图像目标区域精确定位。实验结果表明,本文可对远距(7~25 m)时的加油锥套图像快速进行识别处理,并将锥套目标定位到精确的区域边界。%In the visual-based aerial refueling assistance system, how to separate the refueling drogue from the complex background and do rapid detection of drogue area is an urgent problem. How to detect and locate refueling drogue over a long distance in real-time, a refueling drogue detection and location over a long distance method based on Hough-LS was presented. First, did pre-detection on refueling drogue based on Fast Hough Gradient Method (FHGM), and then extracted taper sleeve edge based on the method of Search in eight directions from the center. Finally, realized refueling taper sleeve detection over a long distance by the least squares fitting ellipse. Experimental results show that, the method has good detection effect for long distance (7 to 25 meters) taper sleeve target and it can locate the precise area boundary.

  12. Scheduling Problem of Aircraft Refueling Vehicle Based on Ant Colony Algorithm%基于蚁群算法的飞机加油车辆调度问题研究

    Institute of Scientific and Technical Information of China (English)

    刘长有; 王一飞

    2014-01-01

    Aircraft refueling is an important part of ground security operations. Reasonable scheduling of aircraft refueling vehicle is the key factor for aircraft to complete the refueling operations on time and quantity, so the research of aircraft refueling vehicle scheduling is very meaningful. This paper firstly introduces the types, functions, driving process and considerations of aircraft refueling vehicle, then specifically describes the model of aircraft refueling vehicle scheduling according to the basic model of vehicle scheduling, finally carries on simulation calculation for the driving situations of airport tank refueling vehicle within three hours in an airport and provides a viable optimization algorithms for aircraft refueling vehicle operation.%飞机加油是停机坪地面保障作业的重要环节,能否对飞机按时按量的完成加油作业的关键因素在于对飞机加油车辆的合理调度,因此对飞机加油车辆调度的研究是十分有意义的。本文首先对飞机加油车辆的类型、功能、行驶过程及其注意事项做了简单的介绍,然后根据车辆调度的基本模型对飞机加油车辆调度的模型进行了比较具体的描述,文章最后用蚁群算法对某机场3个小时内飞机油罐加油车辆行驶情况进行仿真计算,希望通过对该模型的仿真优化计算,为机场加油车辆运行提供一种可行优化算法。

  13. Operational readiness verification, phase 1: A study on safety during outage and restart of nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Hollnagel, E. [Linkoeping Univ. (Sweden). Dept. of Computer and Information Science; Gauthereau, V. [Linkoeping Univ. (Sweden). Dept. of Industrial Engineering

    2001-06-01

    This report contains the findings from the first phase of a study on safety during outage and restart of nuclear power plants. Operational Readiness Verification (ORV) - in Swedish called Driftklarhetsverifiering (DKV) - refers to the test and verification activities that are necessary to ensure that plant systems are able to provide their required functions when needed - more concretely that all plant systems are in their correct functional state when the plant is restarted after an outage period. The concrete background for this work is that nine ORV related incidents were reported in Sweden between July 1995 and October 1998. The work reported here comprised a literature survey of research relevant for ORV issues, and an assessment of the present situation at Swedish NPPs with respect to ORV. The literature survey was primarily aimed at research related to NPPs, but also looked at domains where similar problems have occurred, such as maintenance in commercial aviation. The survey looked specifically for organisational and MTO aspects relevant to the present situation in Swedish NPPs. One finding was that ORV should be seen as an integral part of maintenance, rather than as a separate activity. Another, that there is a characteristic distribution of error modes for maintenance and ORV, with many sequence errors and omissions, rather than a set of unique error modes. An international study further showed that there are important differences in how procedures are used, and in the balance between decentralisation and centralisation. Several studies also suggested that ORV could usefully be described as a barrier system in relation to the flow of work, for instance using the following five stages: (1) preventive actions during maintenance/outage, (2) post-test after completion of work, (3) pre-test before start-up, (4) the start-up sequence itself, and (5) preventive actions during power operation - possibly including automatic safety systems. In the field survey

  14. Simulated annealing and metaheuristic for randomized priority search algorithms for the aerial refuelling parallel machine scheduling problem with due date-to-deadline windows and release times

    Science.gov (United States)

    Kaplan, Sezgin; Rabadi, Ghaith

    2013-01-01

    This article addresses the aerial refuelling scheduling problem (ARSP), where a set of fighter jets (jobs) with certain ready times must be refuelled from tankers (machines) by their due dates; otherwise, they reach a low fuel level (deadline) incurring a high cost. ARSP is an identical parallel machine scheduling problem with release times and due date-to-deadline windows to minimize the total weighted tardiness. A simulated annealing (SA) and metaheuristic for randomized priority search (Meta-RaPS) with the newly introduced composite dispatching rule, apparent piecewise tardiness cost with ready times (APTCR), are applied to the problem. Computational experiments compared the algorithms' solutions to optimal solutions for small problems and to each other for larger problems. To obtain optimal solutions, a mixed integer program with a piecewise weighted tardiness objective function was solved for up to 12 jobs. The results show that Meta-RaPS performs better in terms of average relative error but SA is more efficient.

  15. Some Problems Concerning the Refueling of the Natural Gas Vehicles%天然气汽车燃料加注的几个问题

    Institute of Scientific and Technical Information of China (English)

    高鲁嘉; 鲁雪生; 杨晓东

    2001-01-01

    在天然气汽车(NGVs)的市场推广过程中,以加气站为主的基础设施的建设是关系到天然气汽车发展的关键环节之一文章讨论了一些会对天然气加气站的运行造成影响的问题,包括天然气的预处理问题、充气系统气间歇问题以及高压充气时可能出现的不良节流效应和它们的处理方法。同时从投资与运营角度,对我国不同地区的天然气资源及其所需工艺、不同的加气站类型及其适用对象,进行了综合分析。%During the marketing promotion process of Natural Gas Vehicles(NGVs), the infrastructures, especially the refueling Station, are among the key problems. In this paper, some problems that may cast adverse influence on the proper work of the refueling station, including natural gas pretreatment, gas dischargeing during refueling interval, and the Joule-Thomson effect of the high-pressure charging will be discussed and countermeasures will be provided. Meanwhile, the analysis between the natural gas resources at different places in China along with their appropriate pretreatment and between different refueling models along with their aimed vehicles fleets are presented from the respects of investment and running.

  16. Evaluation of the resilience of a full-scale down-flow hanging sponge reactor to long-term outages at a sewage treatment plant in India.

    Science.gov (United States)

    Onodera, Takashi; Takayama, Daisuke; Ohashi, Akiyoshi; Yamaguchi, Takashi; Uemura, Shigeki; Harada, Hideki

    2016-10-01

    Resilience to process outages is an essential requirement for sustainable wastewater treatment systems in developing countries. In this study, we evaluated the ability of a full-scale down-flow hanging sponge (DHS) reactor to recover after a 10-day outage. The DHS tested in this study uses polyurethane sponge as packing material. This full-scale DHS reactor has been tested over a period of about 4 years in India with a flow rate of 500 m(3)/day. Water was not supplied to the DHS reactor that was subjected to the 10-day outage; however, the biomass did not dry out because the sponge was able to retain enough water. Soon after the reactor was restarted, a small quantity of biomass, amounting to only 0.1% of the total retained biomass, was eluted. The DHS effluent achieved satisfactory removal of suspended solids, chemical oxygen demand, and ammonium nitrogen within 90, 45, and 90 min, respectively. Conversely, fecal coliforms in the DHS effluent did not reach satisfactory levels within 540 min; instead, the normal levels of fecal coliforms were achieved within 3 days. Overall, the tests demonstrated that the DHS reactor was sufficiently robust to withstand long-term outages and achieved steady state soon after restart. This reinforces the suitability of this technology for developing countries.

  17. Assessment of occupational exposure to BTEX compounds at a bus diesel-refueling bay: A case study in Johannesburg, South Africa.

    Science.gov (United States)

    Moolla, Raeesa; Curtis, Christopher J; Knight, Jasper

    2015-12-15

    Of increasing concern is pollution by volatile organic compounds, with particular reference to five aromatic hydrocarbons (benzene, toluene, ethyl benzene and two isomeric xylenes; BTEX). These pollutants are classified as hazardous air pollutants. Due to the potential health risks associated with these pollutants, BTEX concentrations were monitored at a bus diesel-refueling bay, in Johannesburg, South Africa, using gas chromatography, coupled with a photo-ionization detector. Results indicate that o-xylene (29-50%) and benzene (13-33%) were found to be the most abundant species of total BTEX at the site. Benzene was within South African occupational limits, but above international occupational exposure limits. On the other hand, occupational concentrations of toluene, ethyl-benzene and xylenes were within national and international occupational limits throughout the monitoring period, based on 8-hour workday weighted averages. Ethyl-benzene and p-xylene concentrations, during winter, correspond to activity at the site, and thus idling of buses during refueling may elevate results. Overall, occupational air quality at the refueling bay is a matter of health concern, especially with regards to benzene exposure, and future reduction strategies are crucial. Discrepancies between national and international limit values merit further investigation to determine whether South African guidelines for benzene are sufficiently precautionary. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Lightning-Generated Whistler Waves Observed by Probes On The Communication/Navigation Outage Forecast System Satellite at Low Latitudes

    Science.gov (United States)

    Holzworth, R. H.; McCarthy, M. P.; Pfaff, R. F.; Jacobson, A. R.; Willcockson, W. L.; Rowland, D. E.

    2011-01-01

    Direct evidence is presented for a causal relationship between lightning and strong electric field transients inside equatorial ionospheric density depletions. In fact, these whistler mode plasma waves may be the dominant electric field signal within such depletions. Optical lightning data from the Communication/Navigation Outage Forecast System (C/NOFS) satellite and global lightning location information from the World Wide Lightning Location Network are presented as independent verification that these electric field transients are caused by lightning. The electric field instrument on C/NOFS routinely measures lightning ]related electric field wave packets or sferics, associated with simultaneous measurements of optical flashes at all altitudes encountered by the satellite (401.867 km). Lightning ]generated whistler waves have abundant access to the topside ionosphere, even close to the magnetic equator.

  19. Estimation of Outage Capacity for Free Space Optical Links Over I-K and K Turbulent Channels

    Directory of Open Access Journals (Sweden)

    D. Marinos

    2011-06-01

    Full Text Available The free space optical communication systems are attracting great research and commercial interest due to their capability of transferring data, over short distances, with high rate and security, low cost demands and without licensing fees. However, their performance depends strongly on the atmospheric conditions in the link’s area. In this work, we investigate the influence of the turbulence on the outage capacity of such a system for weak to strong turbulence channels modeled by the I-K and the K-distribution and we derive closed-form expressions for its estimation. Finally, using these expressions we present numerical results for various link cases with different turbulence conditions.

  20. The fixed-bias Langmuir probe on the Communication/Navigation Outage Forecast System satellite: calibration and validation.

    Science.gov (United States)

    Klenzing, J; Rowland, D

    2012-11-01

    A fixed-bias spherical Langmuir probe is included as part of the Vector Electric Field Instrument (VEFI) suite on the Communication/Navigation Outage Forecast System (C/NOFS) satellite. C/NOFS gathers data in the equatorial ionosphere between 400 and 860 km, where the primary constituent ions are H(+) and O(+). The ion current collected by the probe surface per unit plasma density is found to be a strong function of ion composition. The calibration of the collected current to an absolute density is discussed, and the performance of the spherical probe is compared to other in situ instruments on board the C/NOFS satellite. The application of the calibration is discussed with respect to future fixed-bias probes; in particular, it is demonstrated that some density fluctuations will be suppressed in the collected current if the plasma composition rapidly changes along with density. This is illustrated in the observation of plasma density enhancements on C/NOFS.

  1. Providing Limited Local Electric Service During a Major Grid Outage: A First Assessment Based on Customer Willingness to Pay.

    Science.gov (United States)

    Baik, Sunhee; Morgan, M Granger; Davis, Alexander L

    2017-06-29

    While they are rare, widespread blackouts of the bulk power system can result in large costs to individuals and society. If local distribution circuits remain intact, it is possible to use new technologies including smart meters, intelligent switches that can change the topology of distribution circuits, and distributed generation owned by customers and the power company, to provide limited local electric power service. Many utilities are already making investments that would make this possible. We use customers' measured willingness to pay to explore when the incremental investments needed to implement these capabilities would be justified. Under many circumstances, upgrades in advanced distribution systems could be justified for a customer charge of less than a dollar a month (plus the cost of electricity used during outages), and would be less expensive and safer than the proliferation of small portable backup generators. We also discuss issues of social equity, extreme events, and various sources of underlying uncertainty. © 2017 Society for Risk Analysis.

  2. The Fixed-Bias Langmuir Probe on the Communication-Navigation Outage Forecast System Satellite: Calibration and Validation

    Science.gov (United States)

    Klenzing, J.; Rowland, D.

    2012-01-01

    A fixed-bias spherical Langmuir probe is included as part of the Vector Electric Field Instrument (VEFI) suite on the Communication Navigation Outage Forecast System (CNOFS) satellite.CNOFS gathers data in the equatorial ionosphere between 400 and 860 km, where the primary constituent ions are H+ and O+. The ion current collected by the probe surface per unit plasma density is found to be a strong function of ion composition. The calibration of the collected current to an absolute density is discussed, and the performance of the spherical probe is compared to other in situ instruments on board the CNOFS satellite. The application of the calibration is discussed with respect to future fixed-bias probes; in particular, it is demonstrated that some density fluctuations will be suppressed in the collected current if the plasma composition rapidly changes along with density. This is illustrated in the observation of plasma density enhancements on CNOFS.

  3. Precise outage analysis of mixed RF/unified-FSO DF relaying with HD and 2 IM-DD channel models

    KAUST Repository

    Al-Ebraheemy, Omer Mahmoud S.

    2017-07-20

    This paper derives and analyzes the outage probability of mixed radio frequency (RF)/unified free space optical (FSO) dual-hop decode-and-forward (DF) relaying scheme, where heterodyne detection (HD) and intensity modulation-direct detection (IM-DD) are considered for FSO detection. In doing that, we correctly utilize, for the first time to the best of our knowledge, a precise channel capacity result for the IM-DD channel. Moreover, this is the first time that not only the (IM-DD input-independent) but also the (IM-DD cost-dependent) AWGN channel is considered in such system analysis. This work assumes that the first hop (RF link) follows Naka-gami-m fading, while the second hop (FSO link) follows Málaga (M) turbulence with pointing error. These fading and turbulence models include other ones (such as Rayleigh fading and Gamma-Gamma turbulence) as special cases, so our analysis can be considered as a generalized one from both RF and FSO fading models point of view. Additionally, the system outage probability is investigated asymptotically in high signal-to-noise ratio (SNR) regime, where a new non-reported diversity order and coding gain analysis are shown. Interestingly, we find that in the FSO hop, based on SNR, the HD or IM-DD cost-dependent results in a same diversity order which is twice the one of IM-DD input-independent. However, based on transmitted power all these FSO detectors result in a same diversity order. Furthermore, we offer simulation results which confirm the derived exact and asymptotic expressions.

  4. Secrecy outage analysis of multi-user multi-eavesdropper cellular networks in the face of cochannel interference

    Directory of Open Access Journals (Sweden)

    Yuan Jiang

    2015-02-01

    Full Text Available This paper studies the physical-layer security of a multi-user multi-eavesdropper cellular network, which is composed of multiple users communicating with a base station while the eavesdroppers may intercept the communications from users to the base station (BS. The cellular network is a time-slotted system with simultaneously transmission, in each time slot, a single user is scheduled to transmit messages to BS while the remaining users opportunistically receive information. Considering multiple users available in the cellular network, we present three multi-user scheduling schemes, namely the round-robin scheduling scheme as well as the suboptimal and optimal user scheduling schemes to improve the security of communication (from users to BS against eavesdropping attacks. We only need to assume that the channel state information (CSI of the main link spanning from users to BS is known in the suboptimal scheduling. On the contrary, the optimal scheduling is designed by assuming that the CSI of the main link and wiretap link (spanning from users to the eavesdropper are available. We further carry out secrecy diversity analysis and show that the round-robin always achieves only one diversity order, whereas the suboptimal and optimal user scheduling schemes achieve the full diversity. In addition, numerical results illustrate that the optimal scheduling performs the best and the round-robin has the worst performance in terms of the secrecy outage probability. Last, as the number of users increases, the secrecy outage probabilities of the suboptimal and optimal scheduling schemes decrease significantly.

  5. Power allocation and achievable data rate in spectrum-sharing channels under adaptive primary service outage constraints

    KAUST Repository

    Yang, Yuli

    2012-09-01

    In this paper, we focus on a cognitive radio network where adaptive modulation is adopted in primary links. The gap between the primary user (PU)\\'s received signal-to-noise ratio (SNR) and the lower SNR boundary of the modulation mode that is being used, provides an interference-tolerable zone. Based on this gap, a secondary user (SU) has an increased opportunity to access the licensed spectrum and to determine the transmit power it should use to keep the PU\\'s quality-of-service (QoS) unaffected. However, since the SU cannot obtain perfect information on the PU\\'s received SNR, it has to choose an SNR point between the lower and upper boundaries of the PU\\'s current modulation mode as if this point were the real SNR received by the PU. Considering this issue, in order to quantify the effect of the SU\\'s transmissions on the PU\\'s QoS, we define the PU\\'s service outage probability and obtain its closed-form expressions by taking into account whether the peak transmit power constraint is imposed on the secondary\\'s transmission or not. Subsequently, we derive the SU\\'s achievable data rate in closed form for counterpart scenarios. Numerical results provided here quantify the relation between the PU\\'s service outage probability and the SU\\'s achievable data rate, which further demonstrate that the higher the peak transmit power a secondary transmitter can support, the better performance the cognitive radio network can achieve. © 2012 IEEE.

  6. Rapid population decline in red knots: fitness consequences of decreased refuelling rates and late arrival in Delaware Bay.

    Science.gov (United States)

    Baker, Allan J; González, Patricia M; Piersma, Theunis; Niles, Lawrence J; do Nascimento, Inês de Lima Serrano; Atkinson, Philip W; Clark, Nigel A; Minton, Clive D T; Peck, Mark K; Aarts, Geert

    2004-04-22

    Most populations of migrant shorebirds around the world are in serious decline, suggesting that vital condition-dependent rates such as fecundity and annual survival are being affected globally. A striking example is the red knot (Calidris canutus rufa) population wintering in Tierra del Fuego, which undertakes marathon 30,000 km hemispheric migrations annually. In spring, migrant birds forage voraciously on horseshoe crab eggs in Delaware Bay in the eastern USA before departing to breed in Arctic polar deserts. From 1997 to 2002 an increasing proportion of knots failed to reach threshold departure masses of 180-200 g, possibly because of later arrival in the Bay and food shortage from concurrent over-harvesting of crabs. Reduced nutrient storage, especially in late-arriving birds, possibly combined with reduced sizes of intestine and liver during refuelling, had severe fitness consequences for adult survival and recruitment of young in 2000-2002. From 1997 to 2002 known survivors in Delaware Bay were heavier at initial capture than birds never seen again, annual survival of adults decreased by 37% between May 2000 and May 2001, and the number of second-year birds in wintering flocks declined by 47%. Population size in Tierra del Fuego declined alarmingly from 51,000 to 27,000 in 2000-2002, seriously threatening the viability of this subspecies. Demographic modelling predicts imminent endangerment and an increased risk of extinction of the subspecies without urgent risk-averse management.

  7. Study Neutronic of Small Pb-Bi Cooled Non-Refuelling Nuclear Power Plant Reactor (SPINNOR) with Hexagonal Geometry Calculation

    Science.gov (United States)

    Nur Krisna, Dwita; Su'ud, Zaki

    2017-01-01

    Nuclear reactor technology is growing rapidly, especially in developing Nuclear Power Plant (NPP). The utilization of nuclear energy in power generation systems has been progressing phase of the first generation to the fourth generation. This final project paper discusses the analysis neutronic one-cooled fast reactor type Pb-Bi, which is capable of operating up to 20 years without refueling. This reactor uses Thorium Uranium Nitride as fuel and operating on power range 100-500MWtNPPs. The method of calculation used a computer simulation program utilizing the SRAC. SPINNOR reactor is designed with the geometry of hexagonal shaped terrace that radially divided into three regions, namely the outermost regions with highest percentage of fuel, the middle regions with medium percentage of fuel, and most in the area with the lowest percentage. SPINNOR fast reactor operated for 20 years with variations in the percentage of Uranium-233 by 7%, 7.75%, and 8.5%. The neutronic calculation and analysis show that the design can be optimized in a fast reactor for thermal power output SPINNOR 300MWt with a fuel fraction 60% and variations of Uranium-233 enrichment of 7%-8.5%.

  8. Conceptual design study on an upgraded future Monju core (2). Core concept with extended refueling interval and increased fuel burnup

    Energy Technology Data Exchange (ETDEWEB)

    Kinjo, Hidehito; Ishibashi, Jun-ichi; Nishi, Hiroshi [Japan Nuclear Cycle Development Inst., Tsuruga Head Office, International Cooperation and Technology Development Center, Tsuruga, Fukui (Japan); Kageyama, Takeshi [Nuclear Energy System Inc., Tokyo (Japan)

    2003-03-01

    A conceptual design study has been performed at the International Cooperation and Technology Development Center to investigate the feasibility of upgraded future Monju cores with extended refueling intervals of 365efpd/cycle and increased fuel burnup of 150 GWd/t. The goal of this study is to demonstrate the possible contribution of Monju to the improved economy and to efficient utilization, as one of the major facilities for fast neutron irradiation. Two design measures have been mainly taken to improve the core fuel burnup and reactivity control characteristics for the extended operating cycle length of 1 year: (1) The driver fuel pin specification with both increased pin diameter of 7.7mm and increased active core height of about 100cm has been chosen to reduce the burnup reactivity swing, (2) The absorber control rod specification has also been changed to enhance the control rod reactivity worth by increasing {sup 10}B-enrichment and absorber length, and to adequately secure the shutdown reactivity margin. The major core characteristics have been evaluated on the core power distribution, safety parameters such as sodium void reactivity and Doppler effect, thermal hydraulics and reactivity control characteristics. The results show that this core could achieve the targeted core performances of 1-year operating cycle as well as 150GWd/t discharged burnup, without causing any significant drawback on the core characteristics and safety aspects. The upgraded core concepts have, therefore, been confirmed as feasible. (author)

  9. Real-time drogue recognition and 3D locating for UAV autonomous aerial refueling based on monocular machine vision

    Institute of Scientific and Technical Information of China (English)

    Wang Xufeng; Kong Xingwei; Zhi Jianhui; Chen Yong; Dong Xinmin

    2015-01-01

    Drogue recognition and 3D locating is a key problem during the docking phase of the autonomous aerial refueling (AAR). To solve this problem, a novel and effective method based on monocular vision is presented in this paper. Firstly, by employing computer vision with red-ring-shape feature, a drogue detection and recognition algorithm is proposed to guarantee safety and ensure the robustness to the drogue diversity and the changes in environmental condi-tions, without using a set of infrared light emitting diodes (LEDs) on the parachute part of the dro-gue. Secondly, considering camera lens distortion, a monocular vision measurement algorithm for drogue 3D locating is designed to ensure the accuracy and real-time performance of the system, with the drogue attitude provided. Finally, experiments are conducted to demonstrate the effective-ness of the proposed method. Experimental results show the performances of the entire system in contrast with other methods, which validates that the proposed method can recognize and locate the drogue three dimensionally, rapidly and precisely.

  10. Design Study of 200MWth Gas Cooled Fast Reactor with Nitride (UN-PuN Fuel Long Life without Refueling

    Directory of Open Access Journals (Sweden)

    Syarifah Ratna Dewi

    2016-01-01

    Full Text Available Design study of 200 MWth Gas Cooled Fast Reactor with UN-PuN fuel long life without refueling has been done. GFR is one type reactor in Generation IV reactor system. It uses helium coolant and fast neutron spectrum. Helium is chemical inert, single phase and low neutron moderation. In this study the calculations are performed by using SRAC code with PIJ calculation for the fuel pin cell calculation and CITATION calculation for core calculation. The data libraries use JENDL 3.2. The variation fuel fractions are 50% until 60%. The diameter active core is 150 cm and the height active core is 100 cm. The reflector radial-axial width is 50 cm. The variation of the powers are 100 MWth up to 500 MWth. The high power causes the high k-eff value. The optimum design is reached when the power is 200 MWth, variation percentage Plutonium for fuel F1:F2:F3=9%:11%:13%. The comparation of fuel:cladding:coolant fraction = 55%:10%:35%. The cooling down time of Plutonium is nine months. The optimum k-eff value is 1.0142 with excess reactivity value 1.403%. The decay of Plutonium decrease k-eff value in the beginning of burn up.

  11. Synthesizing controllers from duration calculus

    DEFF Research Database (Denmark)

    Fränzle, Martin

    1996-01-01

    Duration Calculus is a logic for reasoning about requirements for real-time systems at a high level of abstraction from operational detail, which qualifies it as an interesting starting point for embedded controller design. Such a design activity is generally thought to aim at a control device...... the physical behaviours of which satisfy the requirements formula, i.e. the refinement relation between requirements and implementations is taken to be trajectory inclusion. Due to the abstractness of the vocabulary of Duration Calculus, trajectory inclusion between control requirements and controller designs...... for embedded controller design and exploit this fact for developing an automatic procedure for controller synthesis from specifications formalized in Duration Calculus. As far as we know, this is the first positive result concerning feasibility of automatic synthesis from dense-time Duration Calculus....

  12. LOG DURATION EMERGENCY OXYGEN BACKPACK.

    Science.gov (United States)

    A small backpack , for use by Naval aviators, containing a long duration emergency oxygen system and a separate humidifier for the aircraft’s oxygen supply, has been devised and a feasibility model built. (Author)

  13. 基于运行可靠性模型的连锁故障模拟及薄弱环节分析%The Power System Cascading Outage Simulation and Vulnerability Analysis Based on Operational Reliability Model

    Institute of Scientific and Technical Information of China (English)

    程林; 刘满君; 易俊; 何剑; 贺庆

    2016-01-01

    提出一种基于运行可靠性模型的连锁故障模拟及系统薄弱环节分析方法。该方法结合影响连锁故障各个阶段的关键因素不同,将触发事件与后继发展事件独立,建立发现触发事件的初始故障概率模型,并重点分析后继发展事件的传播特性;其中,根据线路运行可靠性模型,考虑在连锁故障快速发展阶段系统潮流变化对线路停运的影响,从而发现后续发展事件以及连锁故障事件间的相关性;结合运行可靠性模型,搜索系统在不同初始故障下的连锁故障事件,并形成连锁故障事件集;基于连锁故障事件集分析系统薄弱环节及事件相关性,发现系统关键元件。结合算例,通过模拟系统在不同初始故障下的连锁故障事件并分析系统薄弱环节,可以提出相应的系统改造方案,预防连锁故障发生,并可以在事件发展过程中发现后继事件,以便阻止连锁事件进一步演化发展。%This paper proposed a power system cascading outage simulation and vulnerability analysis method based on an operational reliability model. This method firstly considered different factors in different cascading outage stages, and then classified outage events into initial outage and subsequent outage, an initial outage model was given and subsequent outage property was highlighted later. Based on the operational reliability model, impact of load level on transmission lines was taken into consideration in fast outage stage. This model could be used to analyze subsequent outages and interactions between outage events. Cascading outage events for different initial outages were simulated and vulnerability analysis was presented to locate critical component of power system. Case study results showed that this method could simulate cascading outages for different initial outages and find out vulnerable components of power system, some more system improvement measures

  14. Wind turbine outage model based on operation conditions%计及运行工况的风电机组停运模型

    Institute of Scientific and Technical Information of China (English)

    蒋程; 张建华; 刘先正; 于坤山

    2013-01-01

    根据风电机组停运的特点,把其分为电磁系统和机械系统。考虑电网运行工况对风机停运的影响建立了基于电网电压和频率的电磁系统的故障率模型;考虑天气对风机停运的影响建立了基于风速的机械系统的故障率模型,综合上述两方面,得到计及运行工况的风电机组故障率模型。在Matlab中对某1.5 MW风机进行仿真,给出了不同运行工况下风电机组的故障率。此模型能够反映电网运行条件和外界风速对风电机组故障率的影响,能够如实表征风电机组实时运行的安全可靠性水平。%According to the characteristics of outage, the wind turbine is divided into two parts, namely the electromagnetic system and the machinery system. The failure rate model of electromagnetic system based on the grid voltage and frequency is established considering the impact of the grid operating conditions on the wind turbine outage, and the failure rate model of machinery system based on the wind speed is established considering the impact of the weather on the wind turbine outage, then the wind turbine outage rate model based on operating conditions of grid and weather can be obtained. The simulation of 1.5 MW wind turbine is carried out in Matlab, and the outage rate of wind turbine under diffident operation conditions is given. The model can reflect the effect of wind turbine outage rate on the grid operating conditions and external wind speed and can accurately characterize the level of safety and reliability of the wind turbine under real-time operation.

  15. Quantification of risk considering external events on the change of allowed outage time and the preventive maintenance during power operation

    Energy Technology Data Exchange (ETDEWEB)

    Kang, D. J.; Kim, K. Y.; Yang, J. E

    2001-03-01

    In this study, for the major safety systems of Ulchin Units 3/4, we quantify the risk on the change of AOT and the PM during power operation to identify the effects on the results of external events PSA when nuclear power plant changes such as allowed outage time are requested. The systems for which the risks on the change of allowed outage time are quantified are High Pressure Safety Injection System (HPSIS), Containment Spray System (CSS), and Emergency Diesel Generator (EDG). The systems for which the risks on the PM during power operation are Low Pressure Safety Injection System (LPSIS), CSS, EDG, Essential Service Water System (ESWS). Following conclusions can be obtained through this study: 1)The increase of core damage frequency ({delta}CDF) on the change of AOT and the conditional core damage probability (CCDP) on the on-line PM of each system are differently quantified according to the cases of considering only internal events or only external events. . 2)It is expected that the quantification of risk including internal and external events is advantageous for the licensee of NPP if the regulatory acceptance criteria for the technical specification changes are relatively set up. However, it is expected to be disadvantageous for the licensee if the acceptance criteria are absolutely set up. 3)It is expected that the conduction on the quantification of only a fire event is sufficient when the quantification of external events PSA model is required for the plant changes of Korea Standard NPPs. 4)It is expected that the quantification of the increase of core damage frequency and the incremental conditional core damage probability on technical specification changes are not needed if the quantification results of those considering only internal events are below regulatory acceptance criteria and the external events PSA results are not greatly affected by the system availability. However, it is expected that the quantification of risk considering external events

  16. Imprecise Estimation for Conditional Outage Probabilities of Power Components%电力设备停运概率的非精确条件估计

    Institute of Scientific and Technical Information of China (English)

    刁浩然; 杨明; 韩学山; 马世英; 刘道伟; 王剑辉

    2016-01-01

    By using limited outage samples, it is difficult to obtain the operational reliability indexes of power components accurately. Therefore, estimating the fluctuation ranges of the indexes can provide a more objective decision-making basis for power system operational risk control. In this paper, a novel approach was proposed to estimate the imprecise conditional outage probabilities of power components based on the credal network (CN), which could evaluate the interval ranges of conditional probabilities. Based on the historical outage statistics and the component operational conditions at the target period, a credal network, which used the imprecise Dirichlet model (IDM) to get the imprecise probabilistic dependencies, was set up to estimate the imprecise conditional outage probabilities. Therefore, the imprecise outage probabilities of components can be obtained by using the reasoning algorithm of the credal network. The proposed approach can reflect the variation of the conditional outage probabilities with respected to the operational conditions of the power components, and breaks a new way for the reliability assessment of power components with limited outage observations. Results on estimating the imprecise conditional outage probabilities of LGJ-300 transmission lines located in Shandong province illustrate the effectiveness of the proposed approach.%在小样本条件下,电力设备的运行可靠性参数难以精确获取,对其波动范围进行估计,可为电力系统运行提供更为客观、全面的评估与决策依据。由此,该文提出了一种基于信度网络(credal network, CN)的电力设备停运概率的非精确条件估计方法,对暴露型设备运行中条件相依的停运概率指标的区间范围进行估计。该方法基于设备停运的历史统计数据和估计目标时段的运行工况条件,构建了处理非精确条件概率推断问题的信度网络,并利用多状态随机变量的

  17. A Generic Simulation Approach for the Fast and Accurate Estimation of the Outage Probability of Single Hop and Multihop FSO Links Subject to Generalized Pointing Errors

    KAUST Repository

    Ben Issaid, Chaouki

    2017-07-28

    When assessing the performance of the free space optical (FSO) communication systems, the outage probability encountered is generally very small, and thereby the use of nave Monte Carlo simulations becomes prohibitively expensive. To estimate these rare event probabilities, we propose in this work an importance sampling approach which is based on the exponential twisting technique to offer fast and accurate results. In fact, we consider a variety of turbulence regimes, and we investigate the outage probability of FSO communication systems, under a generalized pointing error model based on the Beckmann distribution, for both single and multihop scenarios. Selected numerical simulations are presented to show the accuracy and the efficiency of our approach compared to naive Monte Carlo.

  18. Radiation exposure reduction in APR1400

    Energy Technology Data Exchange (ETDEWEB)

    Bae, C. J.; Hwang, H. R. [Korea Power Engineering Company, Inc., Yongin (Korea, Republic of); Matteson, D. M. [Westinghouse Electric Company, Pittsburgh (United States)

    2003-06-15

    The primary contributors to the total occupational radiation exposure in operating nuclear power plants are operation and maintenance activities during refueling outages. The Advanced Power Reactor 1400 (APR1400) includes a number of design improvements and plans to utilize advanced maintenance methods and robotics to minimize the annual collective dose. The major radiation exposure reduction features implemented in APR1400 are a permanent refueling pool seal, quick opening transfer tube blind flange, improved hydrogen peroxide injection at shutdown, improved permanent steam generator work platforms, and more effective temporary shielding. The estimated average annual occupational radiation exposure for APR1400 based on the reference plant experience and an engineering judgment is determined to be in the order of 0.4 man-Sv, which is well within the design goal of 1 man-Sv. The basis of this average annual occupational radiation exposure estimation is an eighteen (18) month fuel cycle with maintenance performed to steam generators and reactor coolant pumps during refueling outage. The outage duration is assumed to be 28 days. The outage work is to be performed on a 24 hour per day basis, seven (7) days a week with overlapping twelve (12) hour work shifts. The occupational radiation exposure for APR 1400 is also determined by an alternate method which consists of estimating radiation exposures expected for the major activities during the refueling outage. The major outage activities that cause the majority of the total radiation exposure during refueling outage such as fuel handling, reactor coolant pump maintenance, steam generator inspection and maintenance, reactor vessel head area maintenance, decontamination, and ICI and instrumentation maintenance activities are evaluated at a task level. The calculated value using this method is in close agreement with the value of 0.4 man-Sv, that has been determined based on the experience and engineering judgement

  19. Information from a power transmission line process data bank for an expert system following a network outage. Informationen aus einer Netz-Prozessdatenbank fuer ein Expertensystem zum Netzwiederaufbau

    Energy Technology Data Exchange (ETDEWEB)

    Krost, G.; Rumpel, D. (Duisburg Univ. (Gesamthochschule) (Germany, F.R.). Fachgebiet Elektrische Anlagen und Netze)

    1990-03-01

    An expert system can be of great use in unpredictable and time critical situations. For example following a network outage. It helps find solutions to problems and because of its lucidity be used as a training help for control room personnel. Because of the complexity of the information involved in ascertaining the condition of the network, such an expert system must have access to the transmission line process data bank. (orig.).

  20. Analysis and Mitigation of Tropospheric Effects on Ka Band Satellite Signals and Estimation of Ergodic Capacity and Outage Probability for Terrestrial Links

    OpenAIRE

    Enserink, Scott Warren

    2012-01-01

    The first part of this work covers the effect of the troposphere onKa band (20-30 GHz) satellite signals. The second part deals withthe estimation of the capacity and outage probability forterrestrial links when constrained to quadrature amplitudemodulations.The desire for higher data rates and the need for availablebandwidth has pushed satellite communications into the Ka band(20-30 GHz). At these higher carrier frequencies the effects ofscintillation and rain attenuation are increased. In...

  1. Unemployment duration and unemployment insurance

    DEFF Research Database (Denmark)

    Røed, Knut; Jensen, Peter; Thoursie, Anna

    2008-01-01

    Based on pooled register data from Norway and Sweden, we find that differences in unemployment duration patterns reflect dissimilarities in unemployment insurance (UI) systems in a way that convincingly establishes the link between economic incentives and job search behaviour. Specifically, UI...

  2. Extended duration orbiter (EDO) insignia

    Science.gov (United States)

    1990-01-01

    Extended duration orbiter (EDO) insignia incorporates a space shuttle orbiter with payload bay doors (PLBDs) open and a spacelab module inside. Trailing the orbiter are the initials EDO. The EDO-modified Columbia, Orbiter Vehicle (OV) 102, will be flown for the first EDO mission, STS-50.

  3. Short duration gamma ray bursts

    Indian Academy of Sciences (India)

    Patrick Das Gupta

    2004-10-01

    After a short review of gamma ray bursts (GRBs), we discuss the physical implications of strong statistical correlations seen among some of the parameters of short duration bursts (90 < 2 s). Finally, we conclude with a brief sketch of a new unified model for long and short GRBs.

  4. Liner ship refueled strategy considering ship speed%考虑船舶航速的集装箱班轮燃油补给策略

    Institute of Scientific and Technical Information of China (English)

    饶明君; 杨斌; 朱小林; 许波桅

    2015-01-01

    针对集装箱班轮运输中船舶燃油补给问题,分析船舶航速变化对燃油消耗产生的非线性影响,推导出船舶航速与船舶往返时间及船舶油耗之间的关系式,以连续多航次船舶燃油补给总成本最低为目标,加油港与加油量为决策变量,建立周计划内考虑航速的集装箱班轮燃油补给混合整数非线性规划模型。根据模型特点,利用分段线性逼近函数对模型进行等价转换。以某航运公司的亚欧单航线为仿真实验,依次分析港口时间窗、船舶类型、燃油价格及船舶油舱容量等因素对船舶燃油补给策略的影响。结果表明:该模型可以同时决策船舶加油港的选择、加油量的大小及航速的调整,比传统模式更能节省油耗和成本。%In view of the problems of ship′s refueling strategy in container liner transportation network , analysis of the non-linear influence of ship speed on fuel consumption is done and the mathematical functions are deduced to describe the relationships between the ship speed , fuel consumption and the round voyage time .To minimize the ship refueling cost , a mixed integer non-linear programming model considering ship speed is formulated to solve the optimal refueling strategy problem of where to refuel and how much to fuel .According to the characteristics of the model , we utilize piecewise linear approximation function for equivalent model .The single shipping liner service of Asia-Europe is taken as an example for the simulation experiment , the sequence analysis is made of port arrival time windows , and ship type , bunker fuel price , and ship bunker fuel capacity on bunker fuel supply strategy .The results indicate that the proposed model , compared with the conventional model , can simultaneously solve the problems of bunkering port , bunkering amounts and ship speeds adjustment , save fuel consumption and cost .

  5. On the Efficient Simulation of the Distribution of the Sum of Gamma-Gamma Variates with Application to the Outage Probability Evaluation Over Fading Channels

    KAUST Repository

    Ben Issaid, Chaouki

    2016-06-01

    The Gamma-Gamma distribution has recently emerged in a number of applications ranging from modeling scattering and reverbation in sonar and radar systems to modeling atmospheric turbulence in wireless optical channels. In this respect, assessing the outage probability achieved by some diversity techniques over this kind of channels is of major practical importance. In many circumstances, this is intimately related to the difficult question of analyzing the statistics of a sum of Gamma-Gamma random variables. Answering this question is not a simple matter. This is essentially because outage probabilities encountered in practice are often very small, and hence the use of classical Monte Carlo methods is not a reasonable choice. This lies behind the main motivation of the present work. In particular, this paper proposes a new approach to estimate the left tail of the sum of Gamma-Gamma variates. More specifically, we propose a mean-shift importance sampling scheme that efficiently evaluates the outage probability of L-branch maximum ratio combining diversity receivers over Gamma-Gamma fading channels. The proposed estimator satisfies the well-known bounded relative error criterion, a well-desired property characterizing the robustness of importance sampling schemes, for both identically and non-identically independent distributed cases. We show the accuracy and the efficiency of our approach compared to naive Monte Carlo via some selected numerical simulations.

  6. [Responding to patients with home mechanical ventilation after the Great East Japan Earthquake and during the planned power outages. How should we be prepared for a future disaster ?].

    Science.gov (United States)

    Takechi, Yukako

    2011-12-01

    The unprecedented earthquake(magnitude-9 in the Japanese seismic intensity scale)hit off the east coast of Japan on March 11, 2011. Consequently, there were planned power outages in the area nearby Tokyo to avoid massive blackouts caused by a stoppage of Fukushima nuclear plants.Our clinic located in Kawasaki city was also hit by the earthquake(magnitude- 5).During the period of two months(March and April 2011), we had a total of 52 patients with home respiratory care (5-TPPV, 11-NPPV and 36-HOT)at that time.Two out of three 24 hour-TPPV users had no external battery.After the earthquake, there was a 7-hour electricity failure in some areas, and a patient with ASV(adaptive servo ventilator)was living there.Moreover, 3-hour/day power outages were carried out from March 14 to March 28, affecting people's everyday lives. However, the patient had no harmful influences from the power failure because a ventilation company lent us an external battery(4-9 hour life capacity)for the patients, and we were able to avoid an emergency situation caused by the power failure.In conclusion, we ought to be prepared for patients with home mechanical ventilation in the future toward unforeseen large scale power outages.

  7. On the Efficient Simulation of the Distribution of the Sum of Gamma-Gamma Variates with Application to the Outage Probability Evaluation Over Fading Channels

    KAUST Repository

    Issaid, Chaouki ben

    2017-01-26

    The Gamma-Gamma distribution has recently emerged in a number of applications ranging from modeling scattering and reverberation in sonar and radar systems to modeling atmospheric turbulence in wireless optical channels. In this respect, assessing the outage probability achieved by some diversity techniques over this kind of channels is of major practical importance. In many circumstances, this is related to the difficult question of analyzing the statistics of a sum of Gamma- Gamma random variables. Answering this question is not a simple matter. This is essentially because outage probabilities encountered in practice are often very small, and hence the use of classical Monte Carlo methods is not a reasonable choice. This lies behind the main motivation of the present work. In particular, this paper proposes a new approach to estimate the left tail of the sum of Gamma-Gamma variates. More specifically, we propose robust importance sampling schemes that efficiently evaluates the outage probability of diversity receivers over Gamma-Gamma fading channels. The proposed estimators satisfy the well-known bounded relative error criterion for both maximum ratio combining and equal gain combining cases. We show the accuracy and the efficiency of our approach compared to naive Monte Carlo via some selected numerical simulations.

  8. Outage Performance Analysis of Relay Selection Schemes in Wireless Energy Harvesting Cooperative Networks over Non-Identical Rayleigh Fading Channels †

    Science.gov (United States)

    Do, Nhu Tri; Bao, Vo Nguyen Quoc; An, Beongku

    2016-01-01

    In this paper, we study relay selection in decode-and-forward wireless energy harvesting cooperative networks. In contrast to conventional cooperative networks, the relays harvest energy from the source’s radio-frequency radiation and then use that energy to forward the source information. Considering power splitting receiver architecture used at relays to harvest energy, we are concerned with the performance of two popular relay selection schemes, namely, partial relay selection (PRS) scheme and optimal relay selection (ORS) scheme. In particular, we analyze the system performance in terms of outage probability (OP) over independent and non-identical (i.n.i.d.) Rayleigh fading channels. We derive the closed-form approximations for the system outage probabilities of both schemes and validate the analysis by the Monte-Carlo simulation. The numerical results provide comprehensive performance comparison between the PRS and ORS schemes and reveal the effect of wireless energy harvesting on the outage performances of both schemes. Additionally, we also show the advantages and drawbacks of the wireless energy harvesting cooperative networks and compare to the conventional cooperative networks. PMID:26927119

  9. A Short-Term Outage Model of Wind Turbines with Doubly Fed Induction Generators Based on Supervisory Control and Data Acquisition Data

    Directory of Open Access Journals (Sweden)

    Peng Sun

    2016-10-01

    Full Text Available This paper presents a short-term wind turbine (WT outage model based on the data collected from a wind farm supervisory control and data acquisition (SCADA system. Neural networks (NNs are used to establish prediction models of the WT condition parameters that are dependent on environmental conditions such as ambient temperature and wind speed. The prediction error distributions are discussed and used to calculate probabilities of the operation of protection relays (POPRs that were caused by the threshold exceedance of the environmentally sensitive parameters. The POPRs for other condition parameters are based on the setting time of the operation of protection relays. The union probability method is used to integrate the probabilities of operation of each protection relay to predict the WT short term outage probability. The proposed method has been used for real 1.5 MW WTs with doubly fed induction generators (DFIGs. The results show that the proposed method is more effective in WT outage probability prediction than traditional methods.

  10. An Overview of Scientific and Space Weather Results from the Communication/Navigation Outage Forecasting System (C/NOFS) Mission

    Science.gov (United States)

    Pfaff, R.; de la Beaujardiere, O.; Hunton, D.; Heelis, R.; Earle, G.; Strauss, P.; Bernhardt, P.

    2012-01-01

    The Communication/Navigation Outage Forecasting System (C/NOFS) Mission of the Air Force Research Laboratory is described. C/NOFS science objectives may be organized into three categories: (1) to understand physical processes active in the background ionosphere and thermosphere in which plasma instabilities grow; (2) to identify mechanisms that trigger or quench the plasma irregularities responsible for signal degradation; and (3) to determine how the plasma irregularities affect the propagation of electromagnetic waves. The satellite was launched in April, 2008 into a low inclination (13 deg), elliptical (400 x 850 km) orbit. The satellite sensors measure the following parameters in situ: ambient and fluctuating electron densities, AC and DC electric and magnetic fields, ion drifts and large scale ion composition, ion and electron temperatures, and neutral winds. C/NOFS is also equipped with a GPS occultation receiver and a radio beacon. In addition to the satellite sensors, complementary ground-based measurements, theory, and advanced modeling techniques are also important parts of the mission. We report scientific and space weather highlights of the mission after nearly four years in orbit

  11. An exact power series formula of the outage probability with noise and interference over generalized fading channels

    KAUST Repository

    Rached, Nadhir Ben

    2016-12-24

    In this paper, we develop a generalized momentbased approach for the evaluation of the outage probability (OP) in the presence of co-channel interference and additive white Gaussian noise. The proposed method allows the evaluation of the OP of the signal-to-interference-plus-noise ratio by a power series expansion in the threshold value. Its main advantage is that it does not require a particular distribution for the interference channels. The only necessary ingredients are a power series expansion for the cumulative distribution function of the desired user power and the cross-moments of the interferers\\' powers. These requirements are easily met in many practical fading models, for which the OP might not be obtained in closed-form expression. For a sake of illustration, we consider the application of our method to the Rician fading environment. Under this setting, we carry out a convergence study of the proposed power series and corroborate the validity of our method for different values of fading parameters and various numbers of co-channel interferers.

  12. A Unified Moment-Based Approach for the Evaluation of the Outage Probability with Noise and Interference

    KAUST Repository

    Rached, Nadhir Ben

    2016-12-05

    In this paper, we develop a novel moment-based approach for the evaluation of the outage probability (OP) in a generalized fading environment with interference and noise. Our method is based on the derivation of a power series expansion of the OP of the signal-to-interference-plus-noise ratio (SINR). It does not necessitate stringent requirements, the only major ones being the existence of a power series expansion of the cumulative distribution function of the desired user power and the knowledge of the cross-moments of the interferers’ powers. The newly derived formula is shown to be applicable for most of the well-practical fading models of the desired user under some assumptions on the parameters of the powers’ distributions. A further advantage of our method is that it is applicable irrespective of the nature of the fading models of the interfering powers, the only requirement being the perfect knowledge of their crossmoments. In order to illustrate the wide scope of applicability of our technique, we present a convergence study of the provided formula for the Generalized Gamma and the Rice fading models. Moreover, we show that our analysis has direct bearing on recent multi-channel applications using selection diversity techniques. Finally, we assess by simulations the accuracy of the proposed formula for various fading environments.

  13. Use of carbon monoxide alarms to prevent poisonings during a power outage--North Carolina, December 2002.

    Science.gov (United States)

    2004-03-12

    Each year in the United States, approximately 500 persons die from unintentional carbon monoxide (CO) poisoning, often during electric power outages caused by severe storms. Use of residential CO alarms has been recommended to reduce the incidence of CO poisoning. In September 2000, Mecklenburg County, North Carolina (2002 population: 722,367), adopted a public health ordinance requiring a CO alarm in the majority of residences; all-electric residences without attached garages (35.4% of all homes) were exempt. The ordinance also permitted use of alarms without battery back-up. On December 4, 2002, an ice storm caused 78.9% of county households to lose power. During the next 9 days, 124 cases of symptomatic CO poisoning were reported. To characterize these poisonings and the effectiveness of the CO alarm ordinance, local emergency physicians, fire department authorities, and CDC conducted an investigation. This report summarizes the results of that investigation, which determined that 96.2% of the severe poisonings occurred in homes with no reported functioning CO alarm. As a result of these findings, on October 8, 2003, Mecklenburg County officials amended the ordinance to require alarms with battery back-ups in all residences. Officials in other communities should consider enacting such alarm ordinances to prevent CO poisonings.

  14. Exact outage analysis of the effect of co-channel interference on secured multi-hop relaying networks

    Science.gov (United States)

    Quang Nguyen, Sang; Kong, Hyung Yun

    2016-11-01

    In this article, the presence of multi-hop relaying, eavesdropper and co-channel interference (CCI) in the same system model is investigated. Specifically, the effect of CCI on a secured multi-hop relaying network is studied, in which the source communicates with the destination via multi-relay-hopping under the presence of an eavesdropper and CCI at each node. The optimal relay at each cluster is selected to help forward the message from the source to the destination. We apply two relay selection approaches to such a system model, i.e. the optimal relay is chosen based on (1) the maximum channel gain from the transmitter to all relays in the desired cluster and (2) the minimum channel gain from the eavesdropper to all relays in each cluster. For the performance evaluation and comparison, we derived the exact closed form of the secrecy outage probability of the two approaches. That analysis is verified by Monte Carlo simulation. Finally, the effects of the number of hops, the transmit power at the source, relays and the external sources, the distance between the external sources and each node in the system, and the location of the eavesdropper are presented and discussed.

  15. Grid-connected photovoltaic (PV) systems with batteries storage as solution to electrical grid outages in Burkina Faso

    Science.gov (United States)

    Abdoulaye, D.; Koalaga, Z.; Zougmore, F.

    2012-02-01

    This paper deals with a key solution for power outages problem experienced by many African countries and this through grid-connected photovoltaic (PV) systems with batteries storage. African grids are characterized by an insufficient power supply and frequent interruptions. Due to this fact, users who especially use classical grid-connected photovoltaic systems are unable to profit from their installation even if there is sun. In this study, we suggest the using of a grid-connected photovoltaic system with batteries storage as a solution to these problems. This photovoltaic system works by injecting the surplus of electricity production into grid and can also deliver electricity as a stand-alone system with all security needed. To achieve our study objectives, firstly we conducted a survey of a real situation of one African electrical grid, the case of Burkina Faso (SONABEL: National Electricity Company of Burkina). Secondly, as study case, we undertake a sizing, a modeling and a simulation of a grid-connected PV system with batteries storage for the LAME laboratory at the University of Ouagadougou. The simulation shows that the proposed grid-connected system allows users to profit from their photovoltaic installation at any time even if the public electrical grid has some failures either during the day or at night.

  16. 基于工作流的拱墅停电管理系统设计与实现%Design and Implementation of Outage Management System based on Workflow

    Institute of Scientific and Technical Information of China (English)

    葛群波; 杨玉山

    2011-01-01

    This paper introduced workflow technology and the current daily outage management of Gongshu Power Supply Bureau. A workflow technology-based outage management approach, described the outage management system design principle. Discussed some concrete implementations such as process design and power outage notifieationAt the end, draw a conclusion that the outage management system is a good solution to solve outage work of Gongshu power supply bureau.%介绍了工作流技术和目前拱墅供电局日常停电管理现状,提出了一种基于工作流技术实现停电管理的方法,阐述了停电管理系统的设计原理,对流程设计、停电通知等具体实现进行了一定的论述,认为停电管理系统是目前一种较好地解决拱墅供电局停电工作的方案.

  17. 机器视觉辅助的插头锥套式无人机自主空中加油仿真%Machine Vision Aided Simulation of Probe and Drogue Unmanned Aerial Vehicle Autonomous Aerial Refueling

    Institute of Scientific and Technical Information of China (English)

    王旭峰; 董新民; 孔星炜

    2013-01-01

    In order to precisely obtain the relative pose between probe and drogue during unmanned aerial vehicle (UAV) autonomous aerial refueling docking,a machine vision aided simulation scheme of probe-drogue UAV autonomous aerial refueling is proposed.Based on the machine vision,the recognition and tracking algorithm of refueling drogue is investigated.The relative pose between UAV and refueling drogue is estimated by using of Kalman filter algorithm.Experiment results show that the machine vision aided image processing algorithm can recognize and track refueling drogue precisely and the convergence of relative pose errors estimated by the filter algorithm is proved,fulfilling the demand of probe-drogue UAV autonomous aerial refueling.%为准确获取无人机自主空中加油对接阶段受油插头与加油锥套的相对位姿信息,提出一种机器视觉辅助的插头锥套式无人机自主空中加油方案.研究了机器视觉识别跟踪加油锥套的算法,利用卡尔曼滤波算法估计无人机与加油锥套的相对位姿.实验结果表明:机器视觉图像处理算法可精确识别跟踪加油锥套,滤波器估计的相对位姿误差收敛速度较快,满足插头锥套式无人机自主空中加油的需要.

  18. Equipment for decontamination of the bottom of the cavity of NPP. During refueling operations; Equipo para la descontaminacion del fondo de la cavidad de CC.NN. durante las operaciones de recarga de combustible

    Energy Technology Data Exchange (ETDEWEB)

    Vaquer Perez, J. I.; Lacalle Bayo, J.; Martinez Pulgarin, A.

    2013-07-01

    In this work is presented the DEMOS robot, computer designed and developed by Dominguis Group to fund decontamination of nuclear power plants cavity during refueling operations. The aim of the project is soil decontamination of the cavity, at-flooded pool by brushing and vacuuming after operations movement of fuel in order to reduce operational doses to workers and the spread of contamination in the activities undertaken thereafter cavity. Finally, the results obtained when using the DEMOS at the 25th refueling NPP are presented Trillo.

  19. 基于工作票的输变电停电事件自动集成%Transmission power outage automatic integration based on working-ticket

    Institute of Scientific and Technical Information of China (English)

    王伟能; 邓集; 熊金山; 杨银花

    2016-01-01

    随着电能质量在线监测系统深化应用,输变电停电事件自动集成已成为电能质量在线监测系统核心的管理功能,实现了从源头系统采集数据并能自动生成停电事件。但是,停电事件生成后,还需要人工进行判断和修改停电性质及原因,增加了管理人员工作负担,同时也不能保证对相关事件管理和统计的及时性。该论文从技术路线与架构、数据流向和数据研判等方面介绍了一种基于工作票的输变电停电原因自动集成典型设计,在现有电能质量在线监测系统中实现了停电原因自动集成。%With power quality monitoring system deepening application, transmission power outage automatically inte-grated has become the core of the system management functions, which collects data from the source system and can au-tomatically generate a power outage. However, these manually judgment and modification the nature and reasons for power outages are need after power outage generating, which increases management burden and can not guarantee that the relevant incident management and timeliness of statistics. This paper presents a typical design for transmission pow-er outage automatic integration based on working-ticket, including technological route, data flow, data judging and so on, which realized the causes of power failures automatically integrated in an existing power quality monitoring system.

  20. 分层网络下行中断概率的闭式表达%Closed Expressions of Downlink Outage Probability in Tiered Networks

    Institute of Scientific and Technical Information of China (English)

    张文健; 田茂; 何浩; 沈祖康

    2011-01-01

    针对用边界值形式表示的共信道干扰限制分层网络的下行中断概率不够精确的问题,采用随机几何理论建模网络结构,并在此基础上推导了每层下行中断概率的闭式表达式.首先构建了关于宏小区信号功率和毫微微小区聚合干扰功率的下行接收信干比函数,然后以聚合干扰功率为条件,根据宏小区信号功率的概率分布推导了接收信干比不高于门限值的概率,最后利用聚合干扰功率的概率分布计算条件中断概率的期望值,得到了中断概率闭式表达式.仿真结果表明:当毫微微小区基站发射功率降低3.16 mW(小区平均数为100),或小区平均数减少20个(基站发射功率为100 mW)时,能够分别使宏小区下行中断概率减小约20%或5%.%Since the downlink outage probability expressed with bound value is not precise enough in co-channel interference-limited tiered networks, the stochastic geometry theory is used to model network framework and closed-expressions of per-tier downlink outage probability are derived based on the framework. The received signal to interference ratio (SIR) is formulated as a function of macrocell signal power and femtocell aggregated interference power. Then the probability for received SIR less than a threshold is derived according to the probability distribution of macro-cell signal power in the condition on the aggregated interference power. The downlink outage probability is obtained by applying the probability distribution of aggregated interference power to calculate the expectation of conditioned outage probability. Simulation results show that the downlink outage probability in macrocell reduces about 20% and 5%, respectively, when the femtocell transmit power decreases 3. 16 mW (the number of femtocells is 100 on average) or the number of femtocells decreases 20 on average (the femtocell transmit power is 100 mW).

  1. Level Crossing Rate and Average Fade Duration of Dual Selection Combining with Cochannel Interference and Nakagami Fading

    CERN Document Server

    Hadzi-Velkov, Zoran

    2009-01-01

    This letter provides closed-form expressions for the outage probability, the average level crossing rate (LCR) and the average fade duration (AFD) of a dual diversity selection combining (SC) system exposed to the combined influence of the cochannel interference (CCI) and the thermal noise (AWGN) in Nakagami fading channel. The branch selection is based on the desired signal power SC algorithm with all input signals assumed to be independent, while the powers of the desired signals in all diversity branches are mutually equal but distinct from the power of the interference signals. The analytical results reduce to known solutions in the cases of an interference-limited system in Rayleigh fading and an AWGN-limited system in Nakagami fading. The average LCR is determined by an original approach that does not require explicit knowledge of the joint PDF of the envelope and its time derivative, which also paves the way for similar analysis of other diversity systems.

  2. Automatic Centralized Refueling Technology for Shearer Gearbox%采煤机齿轮箱自动集中加油技术研究

    Institute of Scientific and Technical Information of China (English)

    高俊光; 廉自生

    2015-01-01

    Based on the existing technologies of automatic refueling of shearer at home and abroad ,an automatic centralized refueling method for the gearboxes in shearer was proposed in this paper .Through the calculation related to oil pressure ,flow and other tech‐nical parameters ,we completed the design of the main components in this system ,to achieve the technology used in shearer .%通过对采煤机现有加油技术及国内外自动加油技术研究,提出了一种采煤机齿轮箱自动集中加油技术;通过对相关油品、油压、流量及液压阀组等技术参数的设计计算,完成了主要元器件的型号设计,实现了该技术在采煤机上的应用。

  3. Outage analysis of selective cooperation in underlay cognitive networks with fixed gain relays and primary interference modeling

    KAUST Repository

    Hussain, Syed Imtiaz

    2012-09-01

    Selective cooperation is a well investigated technique in non-cognitive networks for efficient spectrum utilization and performance improvement. However, it is still a nascent topic for underlay cognitive networks. Recently, it was investigated for underlay networks where the secondary nodes were able to adapt their transmit power to always satisfy the interference threshold to the primary users. This is a valid assumption for cellular networks but many non-cellular devices have fixed transmit powers. In this situation, selective cooperation poses a more challenging problem and performs entirely differently. In this paper, we extend our previous work of selective cooperation based on either hop\\'s signal to noise ratio (SNR) with fixed gain and fixed transmit power relays in an underlay cognitive network. This work lacked in considering the primary interference over the cognitive network and presented a rather idealistic analysis. This paper deals with a more realistic system model and includes the effects of primary interference on the secondary transmission. We first derive end-to-end signal to interference and noise ratio (SINR) expression and the related statistics for a dual-hop relay link using asymptotic and approximate approaches. We then derive the statistics of the selected relay link based on maximum end-to-end SINR among the relays satisfying the interference threshold to the primary user. Using this statistics, we derive closed form asymptotic and approximate expressions for the outage probability of the system. Analytical results are verified through simulations. It is concluded that selective cooperation in underlay cognitive networks performs better only in low to medium SNR regions. © 2012 IEEE.

  4. Rent Control and Unemployment Duration

    DEFF Research Database (Denmark)

    Munch, Jacob R.; Rosholm, Michael; Svarer, Michael

    2005-01-01

    In this paper we analyse how rent control affects the duration of individual unemployment. In atheoretical search model we distinguish between two effects of rent control. On one hand, rentcontrol reduces housing mobility and hence mobility in the labour market. On the other hand, tomaintain rent...... control benefits, unemployed individuals are more likely to accept job offers in the local labour market. Based on a rich Danish data set, we find that the probability of finding a local job increases with the rent control intensity of the housing unit, whereas the probability of finding ajob outside...

  5. Unemployment duration and unemployment insurance

    DEFF Research Database (Denmark)

    Røed, Knut; Jensen, Peter; Thoursie, Anna

    2008-01-01

    Based on pooled register data from Norway and Sweden, we find that differences in unemployment duration patterns reflect dissimilarities in unemployment insurance (UI) systems in a way that convincingly establishes the link between economic incentives and job search behaviour. Specifically, UI...... benefits are relatively more generous for low-income workers in Sweden than in Norway, leading to relatively longer unemployment spells for low-income workers in Sweden. Based on the between-countries variation in replacement ratios, we find that the elasticity of the outflow rate from insured unemployment...

  6. Vowel duration issue in Civili

    OpenAIRE

    Ndinga-Koumba-Binza, Hugues Steve

    2009-01-01

    The main goal of this article is to define the problem of vowel duration in Civili (H12a). It shows that the so-called Civili vowel-length desperately needs to be re-examined, because previous works on the sound system of this language hardly explain a number of phonological phenomena, such as vowel lengthening, on the basis of data at hand. Demonstrating the problem in question, the author first reviews previous works that all identify a vowel lengthening in Civili. From different analyses t...

  7. 直流输电系统强迫停运探讨%Discussion on forced outages of HVDC transmission system

    Institute of Scientific and Technical Information of China (English)

    朱韬析; 李娟; 王超; 陈为化

    2009-01-01

    There are many protection and monitoring functions in HVDC transmission system. Although the equipments are completely protected, the mal-operation is very difficult to be avoided. In this paper, based on the experiences of Tian-Guang HVDC transmission system, the forced outage and the protection and monitoring which would cause forced outage are introduced first, then the reason caused forced outages in operation in those years and its effect are analyzed. At last, combined with the safety of equipments and the reliability of power system, the improving suggestion to the protection and monitoring function in HVDC transmission system is discussed.%直流输电系统中设置了大量的保护、监视功能,但在确保设备安全的同时,也带来了容易误动的隐患.以天广直流输电系统为例,首先介绍了直流输电系统的强迫停运及可能引起强迫停运的保护监视功能,接着讨论了多年来运行中发生的强迫停运故障原因及故障时对设备的影响,最后综合考虑设备的安全和电网的稳定,对直流输电系统的保护、监视功能提出了改进建议.

  8. Two-way中继系统中基于最小化中断概率的功率分配策略%Optimal power allocation scheme based on minimizing outage probability in Two-way relay system

    Institute of Scientific and Technical Information of China (English)

    刘通; 陈前斌; 唐伦; 张力生

    2011-01-01

    为了降低Two-way中继系统中断概率,提出了一种Two-way中继系统中基于最小化中断概率的功率分配策略.首先推导了Two-way中继系统中断概率的闭合表达式,然后在总功率受限的条件下,提出了一种最小化中断概率的最优功率分配策略(OPA),通过拉格朗日乘数法对该优化模型进行了求解.仿真结果证明了该策略能够有效降低系统的中断概率,提高系统性能.%In order to decrease the outage probability of Two-way relay system, this paper proposed an optimal power allocation scheme based on minimizing outage probability. It first derived the close form of outage probability in Two-way relay system, then proposed an optimal power allocation (OPA) scheme to minimize the outage probability under the condition that total power was limited. Solved the optimal model by Lagrange multiplier method. Simulation result shows that the proposed strategy can decrease the outage probability and enhance the performance of the system.

  9. 基于仿真的作战飞机管道加油调度优化研究%Scheduling Optimization of Combat Aircraft Pipeline Refueling Based on Simulation

    Institute of Scientific and Technical Information of China (English)

    王世宏; 雍岐东; 李横; 岳亮

    2013-01-01

      针对多机种作战飞机管道油料加注调度优化的现实问题,通过研究作战飞机从到达基地到加油完毕的油料加注周期,提出了一种新的管道加油口选择策略,并基于此策略研制了以作战飞机数量和油料加注时间为仿真结束条件的2种GPSSW仿真程序模型。通过多次仿真实验,结果表明:该策略优于基于调度人员经验的“即空即用”管道加油口选择策略,可有效提高作战飞机油料加注效率,并能实现有限管道加油口的合理分配。%In order to solve the practical scheduling optimization problem of multitype combat aircraft pipeline refueling,a new selection strategy is proposed for pipeline refueling adapters according to the combat aircraft refueling cycles from aircraft arriv⁃ing airport to fueling over. Based on the new selection strategy,two types of general purpose system simulation world(GPSSW)mod⁃els,which are conditional on combat aircrafts quantity and refueling time,are programmed. Through numerical simulation of two types of models,the test results indicate that the new selection strategy gains an advantage over the traditional selection based on ex⁃periences of scheduling personnel,increases the refueling efficiency of combat aircraft,and achieves the oil filler of limited pipeline channels’reasonable arrangement.

  10. Neurocognition and Duration of Psychosis

    DEFF Research Database (Denmark)

    Rund, Bjørn Rishovd; Barder, Helene Eidsmo; Evensen, Julie

    2016-01-01

    A substantial proportion of schizophrenia-spectrum patients exhibit a cognitive impairment at illness onset. However, the long-term course of neurocognition and a possible neurotoxic effect of time spent in active psychosis, is a topic of controversy. Furthermore, it is of importance to find out...... what predicts the long-term course of neurocognition. Duration of untreated psychosis (DUP), accumulated time in psychosis the first year after start of treatment, relapse rates and symptoms are potential predictors of the long-term course. In this study, 261 first-episode psychosis patients were...... relationship between psychosis before (DUP) or after start of treatment and the composite score was found, providing no support for the neurotoxicity hypothesis, and indicating that psychosis before start of treatment has no significant impact on the course and outcome in psychosis. We found no association...

  11. Cohabitation Duration and Transient Domesticity.

    Science.gov (United States)

    Golub, Andrew; Reid, Megan; Strickler, Jennifer; Dunlap, Eloise

    2013-01-01

    Research finds that many impoverished urban Black adults engage in a pattern of partnering and family formation involving a succession of short cohabitations yielding children, a paradigm referred to as transient domesticity. Researchers have identified socioeconomic status, cultural adaptations, and urbanicity as explanations for aspects of this pattern. We used longitudinal data from the 2001 Survey of Income and Program Participation to analyze variation in cohabitation and marriage duration by race/ethnicity, income, and urban residence. Proportional hazards regression indicated that separation risk is greater among couples that are cohabiting, below 200% of the federal poverty line, and Black but is not greater among urban dwellers. This provides empirical demographic evidence to support the emerging theory of transient domesticity and suggests that both socioeconomic status and race explain this pattern. We discuss the implications of these findings for understanding transient domesticity and make recommendations for using the Survey of Income and Program Participation to further study this family formation paradigm.

  12. 低压故障停电报警系统%Low Pressure Fault Outage Alarm System

    Institute of Scientific and Technical Information of China (English)

    熊俊锋; 丁月明

    2013-01-01

      供电可靠性要求越来越高,对低压配电线路的供电情况一直缺乏监测,不能随时掌握台变的运行情况,如果台变发生跳闸事故,只能通过用户打电话通知电力部门,经常出现停电后不能得到即时地处理,给用户带来工作、生活的不便,长时间的停电也会带来很大的经济损失。分析发生故障停电后报修不及时的原因和对策,研制了一套低压停电故障报警监测系统,在台变跳闸停电后能够通知电力抢修部门,使故障停电报修的时间尽可能的缩短,有效的减少了故障停电时间,提高了供电可靠性,同时有效地提高了供电企业的优质服务水平。%There is higher demand for supply reliability. There is not enough monitoring of the supply of low-voltage distribution lines, and so we can not keep up operation of bench transformer. If the bench transformer occurs tripping accident, we can notify the power sector only through user's call. If the blackouts are often and can not be immediately treated, it will bring inconveniences to the work and living of the user, and also will bring great economic losses. This paper analyzed the causes and countermeasures for not timely repair to failure blackout, developed a set of low-voltage power failure alarm monitoring system which can send the tripping blackout to electrical repair department, reduce the repair time and effectively reduce the fault outage time, improve the reliability of power supply, at the same time improve the level of quality service of power supply enterprise.

  13. Power Outage - 16 October

    CERN Multimedia

    2014-01-01

    At 19:03 last night, a fire in an 18kV circuit breaker in building 212 led to a blackout on the Meyrin site. The CERN fire brigade rapidly brought the fire under control and power was restored by 22:25. Many CERN systems were affected and have been brought back in to service overnight, this work will continue through the day.

  14. Evaluating the Magnitude and Duration of Cold Load Pick-up on Residential Distribution Feeders Using Multi-State Load Models

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Kevin P.; Sortomme, Eric; Venkata, S. S.; Miller, Melanie T.; Ponder, Leslie

    2016-09-01

    The increased level of demand that is associated with the restoration of service after an outage, Cold Load Pick-Up (CLPU), can be significantly higher than pre-outage levels, even exceeding the normal distribution feeder peak demand. These high levels of demand can delay restoration efforts and in extreme cases damage equipment. The negative impacts of CLPU can be mitigated with strategies that restore the feeder in sections, minimizing the load current. The challenge for utilities is to manage the current level on critical equipment while minimizing the time to restore service to all customers. Accurately modeling CLPU events is the first step in developing improved restoration strategies that minimize restoration times. This paper presents a new method for evaluating the magnitude of the CLPU peak, and its duration, using multi-state load models. The use of multi-state load models allows for a more accurate representation of the end-use loads that are present on residential distribution feeders.

  15. Research and Practice of DC Power Double Renovation without Power Outage%直流电源双重化改造不停电策略研究与实践

    Institute of Scientific and Technical Information of China (English)

    仇群辉; 傅进; 费云中; 颜彦

    2015-01-01

    结合直流电源双重化改造实践,对一次设备停电方式、保护轮停方式和不停电方式下设备操作量、操作时间、作业人数以及改造时间进行比较分析,研究出一种不停电改造方法并建议推广应用。%Through double renovation of DC power, equipment operation amount, operation time, number of operators and renovation time of primary equipment outage, alternate outage of relay protection and non-out-age are compared and analyzed. In the final, a non-outage scheme is developed and widely applied.

  16. Application of Generators Unplanned Outage Monitoring of Shanxi Power Grid%山西电网机组非计划停运监测应用研究

    Institute of Scientific and Technical Information of China (English)

    徐宏锐

    2015-01-01

    To solve the problem of generators unplanned outage in Shanxi power grid, we developed the monitoring module of harmonious dispatch supporting system by using its on-line monitoring function. By analyzing, we can predict in advance the potential risks and the cause of generators unplanned outage. The application effectively filled the blank of the impact on the security and stability of Shanxi Power Grid, which not only prepared for the power balance in days or a few days ago, but also made a strong technical support for the safe and stable operation of the power grid.%针对山西电网发电机组非停事件,利用和谐调度系统在线监测功能,开发了和谐系统机组非停监测模块,并将其应用到了非停原因分析中.通过分析,可以提前判断机组非停的潜在风险及故障原因.有效填补了机组非停影响电网安全稳定的空白,为日内或日前电网平衡做好充分准备,且为电网安全稳定运行提供有力的技术保障.

  17. On the Required Number of Antennas in a Point-to-Point Large-but-Finite MIMO System: Outage-Limited Scenario

    KAUST Repository

    Makki, Behrooz

    2016-03-22

    This paper investigates the performance of the point-To-point multiple-input-multiple-output (MIMO) systems in the presence of a large but finite numbers of antennas at the transmitters and/or receivers. Considering the cases with and without hybrid automatic repeat request (HARQ) feedback, we determine the minimum numbers of the transmit/receive antennas, which are required to satisfy different outage probability constraints. Our results are obtained for different fading conditions and the effect of the power amplifiers efficiency/feedback error probability on the performance of the MIMO-HARQ systems is analyzed. Then, we use some recent results on the achievable rates of finite block-length codes, to analyze the effect of the codewords lengths on the system performance. Moreover, we derive closed-form expressions for the asymptotic performance of the MIMO-HARQ systems when the number of antennas increases. Our analytical and numerical results show that different outage requirements can be satisfied with relatively few transmit/receive antennas. © 1972-2012 IEEE.

  18. 基于自适应匹配模型的停电管理系统设计与应用%The design and application of power outage managing system based on data automatic matching model

    Institute of Scientific and Technical Information of China (English)

    熊淦辉; 黎沛坚; 徐俊林; 刘斯烟; 刘柳

    2015-01-01

    文中设计了停电管理系统。该系统通过集成计量自动化系统、营销管理系统、生产系统以及营配数据中心,实现所有专变客户、公变台区停电时间的自动采集,并采用国际标准强化分析方法和停电时间统计自适应匹配模型,实现客户停电时间统计自动化、提高客户停电时间数据统计及时性和准确性。通过在东莞供电局进行的测试运行试点和应用,表明文中设计的客户停电应用管理系统可以使客户停电时间统计准确率提高50%以上。%This thesis designsa power outage managing system. The system integratesmetering automation system、marketing management information system、production system、marketing and distribution data center tocollect power outage time of all special transformer customers and public transformer districtsautomatically . It not just realizes the automatic statistics of customer outage time but also improves effectivenessand accuracyof statistics for customer outage time throughadoptinganalysis method based oninternational standards and the automatic matching model.The trial operation and application in Dongguan power supply bureau show that power outage managing system which the thesis designs can raise the accuracy of statisticsfor customer outage timemore than 50%.

  19. 47 CFR 4.7 - Definitions of metrics used to determine the general outage-reporting threshold criteria.

    Science.gov (United States)

    2010-10-01

    ...) Assigned numbers are defined as the telephone numbers working in the Public Switched Telephone Network...) Administrative numbers are defined as the telephone numbers used by communications providers to perform internal... telephone number minutes are defined as the mathematical result of multiplying the duration of an...

  20. The effect of predictability on subjective duration.

    Directory of Open Access Journals (Sweden)

    Vani Pariyadath

    Full Text Available Events can sometimes appear longer or shorter in duration than other events of equal length. For example, in a repeated presentation of auditory or visual stimuli, an unexpected object of equivalent duration appears to last longer. Illusions of duration distortion beg an important question of time representation: when durations dilate or contract, does time in general slow down or speed up during that moment? In other words, what entailments do duration distortions have with respect to other timing judgments? We here show that when a sound or visual flicker is presented in conjunction with an unexpected visual stimulus, neither the pitch of the sound nor the frequency of the flicker is affected by the apparent duration dilation. This demonstrates that subjective time in general is not slowed; instead, duration judgments can be manipulated with no concurrent impact on other temporal judgments. Like spatial vision, time perception appears to be underpinned by a collaboration of separate neural mechanisms that usually work in concert but are separable. We further show that the duration dilation of an unexpected stimulus is not enhanced by increasing its saliency, suggesting that the effect is more closely related to prediction violation than enhanced attention. Finally, duration distortions induced by violations of progressive number sequences implicate the involvement of high-level predictability, suggesting the involvement of areas higher than primary visual cortex. We suggest that duration distortions can be understood in terms of repetition suppression, in which neural responses to repeated stimuli are diminished.

  1. From Sleep Duration to Childhood Obesity

    DEFF Research Database (Denmark)

    Börnhorst, Claudia; Hense, Sabrina; Ahrens, Wolfgang

    2012-01-01

    Sleep duration has been identified as risk factor for obesity already in children. Besides investigating the role of fat mass (FM), this study addressed the question whether endocrine mechanisms act as intermediates in the association between sleep duration and overweight/obesity. Within......-specific measure of sleep duration was derived to account for alteration in sleep duration during childhood/period of growth. Multivariate linear regression and quantile regression models confirmed an inverse relationship between sleep duration and measures of overweight/obesity. The estimate for the association...... of sleep duration and body mass index (BMI) was approximately halved after adjustment for FM, but remained significant. The strength of this association was also markedly attenuated when adjusting for insulin mainly for the upper BMI quantiles (Q80, β = −0.36 vs. β = −0.26; Q95, β = −0.87 vs. β = −0...

  2. Incorporating Duration Information in Activity Recognition

    Science.gov (United States)

    Chaurasia, Priyanka; Scotney, Bryan; McClean, Sally; Zhang, Shuai; Nugent, Chris

    Activity recognition has become a key issue in smart home environments. The problem involves learning high level activities from low level sensor data. Activity recognition can depend on several variables; one such variable is duration of engagement with sensorised items or duration of intervals between sensor activations that can provide useful information about personal behaviour. In this paper a probabilistic learning algorithm is proposed that incorporates episode, time and duration information to determine inhabitant identity and the activity being undertaken from low level sensor data. Our results verify that incorporating duration information consistently improves the accuracy.

  3. 5 CFR 330.1102 - Duration.

    Science.gov (United States)

    2010-01-01

    ... PLACEMENT (GENERAL) Federal Employment Priority Consideration Program for Displaced Employees of the District of Columbia Department of Corrections § 330.1102 Duration. This program terminates 1 year...

  4. 考虑服务容量的充电站选址问题%Problem of Locating Electric Vehicle Refueling Stations with Service Capacity

    Institute of Scientific and Technical Information of China (English)

    黄振森; 杨臖

    2015-01-01

    针对电动汽车充电站的选址问题,在现有的选址模型的基础上加入充电站服务容量的因素,并将服务容量延伸为充电站充电桩的数量和用电配额两方面,建立了一个新的充电站选址的整数规划模型。该模型的目的是在满足各个地点的电动汽车对电量需求的前提下,最小化充电站建设总成本。接着,将模型应用到湖北省高速公路网电动汽车充电站建设规划的案例中去,通过对模型的求解来对该地区的充电站的选取与规模的大小进行分析,给出湖北省高速公路网充电站建设规划的解决方案。最后,针对车辆的最大行驶范围和安全电量水平两个参数来对模型进行了敏感度分析,发现行驶范围和安全电量水平是影响充电站建设的重要因素。%This paper studied the problem of locating electric vehicle refueling stations.Based on the existing models,we purposed a new model using an integer programming method which took service capacity of refueling stations in to consideration.The aim is to simultaneously serve intercity and intra-city travel and minimize the construction cost while satisfying demand of electric power from refueling stations.The model divided the service capacity into two parts:the number of charging point and the maximum electricity available.A numerical example using freeway network in Hubei province of China was given.We analyzed the result and drew conclusion about the characteristic of station selected.Some sensitivity analysis about this model was showed.Two factors are mainly considered:the maximum range and the safety electric quantity remained of EV,and the results under different conditions.The result showed that two factors had a great effect on the number of stations and the construction cost.Based on the non-inferior solutions,decision makers can thus better formulate viable station-deployment plans.

  5. Optimal power allocation scheme based on minimizing outage probability in two-path relay system%Two-path中继系统中基于最小化中断概率的功率分配方法

    Institute of Scientific and Technical Information of China (English)

    方恒刚; 李莉; 张静; 罗汉文

    2013-01-01

    In order to decrease the outage probability of two-path relay system, this paper derived a closed-form solution of outage probability in DF two-path relay system with the inter-relay interference, and then proposed an optimal power allocation algorithm to minimize the outage probability under the limited total power. The simulation results show that this algorithm can effectively decrease the outage probability and improve the performance of the system.%为了降低two-path中继系统的通信中断概率,针对DF协议中继,推导了two-path中继系统在存在中继间干扰情况下的中断概率闭式解,并在总功率受限的情况下,提出了一种最小化中断概率的最优功率分配算法.仿真验证结果表明该算法能够有效地降低系统的中断概率,提高系统的性能.

  6. 双层异构网络下行中断概率及功率控制研究%Downlink Outage Probability and Power Control in Two-tier Heterogeneous Network

    Institute of Scientific and Technical Information of China (English)

    全震; 滕世海

    2016-01-01

    针对双层异构网络架构复杂、干扰严重的问题,利用空间泊松点过程对Macro-Femto双层网络进行了数学建模,推导了室外MUE和室内FUE的下行中断概率,并提出了基于距离和中断概率的家庭基站覆盖及功率控制优化方案.仿真实验表明,所推导的中断概率表达式是正确的,所提出的方案明显减少了宏用户所受的干扰,降低了宏用户的中断概率,有效提升了整个异构网络的性能.%Aiming at complex architecture and serious interference in two-tier heterogeneous network, the mathematical model of Macro-Femto system is established by using the spatial Poisson point process, and the downlink outage probability of the outdoor Macro users and the indoor Femto users derived, and the optimization scheme of Femtocell coverage and power control based on the distance and outage probability also proposed. Simulation results show that the derived outage probability expression is correct, and the proposed scheme could significantly reduce the interference and outage probability of the macro user, and effectively improves the performance of the whole heterogeneous network.

  7. Investigation of Teaching Pattern about Refueling Equipments Course with Mixed Training of Information Literacy%融合信息素质培养的油料装备课程教学模式

    Institute of Scientific and Technical Information of China (English)

    叶有义; 陈军; 何德安

    2013-01-01

    构建信息素质教育体系,造就信息素质全面的人才,重要要求就是将信息素质培养融入一般课程教学。油料装备课程教学融合信息素质的培养对打造信息化的油料装备人才至关重要,应采取两点措施:一是在教学内容中融入油料装备信息化知识;二是选择与学员信息素质培养相适应的教学模式与教学手段。文章探讨了油料装备信息化知识的主要内容,选择并阐释了相应的教学模式与教学手段,创新了课程教学。%The important requirement for constructing information literacy of educated system and training perfect information literacy talents is to mix information literacy training into ordinary teaching courses. It is a key factor that training informative talent in refueling equipments through mixing information literacy fostering into teaching course about refueling equipments. In order to realize the goals, the following two measures were adopted. The first is fusing informative knowledge about refueling equipment into teaching content; The second is to choose teaching pattern and teaching method suitable for training information literacy students. In this paper, we discussed the main content about informative knowledge of refueling equipments, chose and explained corresponding teaching pattern and teaching methods so as to innovate course teaching.

  8. 配电网可靠性评估中预安排停电的实用数学模型%Mathematical Model of Scheduled Outage in Reliability Assessment of Distribution Network

    Institute of Scientific and Technical Information of China (English)

    王浩浩; 管霖; 吴熳红

    2011-01-01

    目前国内城市配电网的停电事件中预安排停电占据绝对多数,但现有的配电网可靠性理论评估却只考虑了故障停电,缺少对预安排停电影响的评估模型和方法。文中分析了预安排停电的建模特点、导致预安排停电的各类工程、检修项目的不同影响范围。在此基础上,将各类预安排停电项目分为4类停电事件,并分别给出对应的可靠性评估数学模型。模型用于电网规划时,还考虑了新出线网架信息不全给转供判断带来的问题并提出简化处理方法。以珠海市香洲区2010年的项目规划为算例的结果表明,基于项目分类的预安排停电影响的模型具有一定的实用性,适用于配电网可靠性评估。%At present,the scheduled outages account for most of all the outages in the city distribution network,but the existing evaluation methods only take fault outage into account,while neglecting assessment models and methods for scheduled outage.The characteristics of the scheduled outage model and several types of construction/maintenance projects leading to scheduled outage and their impact range are analyzed first.Then,the projects are categorized into four sets based on their impact,with the mathematical model developed for each.The issue of the network structure uncertainty arising from new outlet feeders that brings difficulty to load transfer judgement is also considered in the proposed models.The planning project in Xiangzhou district of Zhuhai city is used as a real example,the results showing that the proposed scheduled outage model is effective in reliability assessment of distribution network.

  9. Application and Fast Simulation of Cascading Outage Based on Genetic Algorithms%基于遗传算法的连锁故障快速模拟及应用

    Institute of Scientific and Technical Information of China (English)

    程林; 刘满君; 何剑

    2015-01-01

    At present,China has finally entered a fast developing period characterized by trans-regional mutual supply,ultra high voltage(UHV),extra high voltage(EHV)and AC-DC hybrid transmission.However,this has led to the staggering rate of power electric system complexity that increases the risk of cascading outage and blackout.A power system cascading outage simulation algorithm is proposed based on genetic algorithms.In searching for the paths with great risk of cascading outage, the algorithm takes the real-time operation environment into consideration while simulating the process of biological evolution based on natural selection.Finally probable cascading outage paths caused by different initial states are found.A case study shows that this algorithm is able to quickly simulate cascading outage,locate critical points of the system and issue alarm of outage,while providing further support to dispatchers in stopping cascading outage in its initial state.%目前,中国电网已进入跨大区互联,超、特高压交直流混合输电的快速发展时期,电网复杂程度急剧增加,发生连锁故障以致引发大面积停电事故的风险逐渐增加。文中在现有连锁故障算法研究的基础上,提出一种基于遗传算法的连锁故障快速模拟算法。该算法应用遗传算法理论,考虑系统运行条件影响,通过模拟基于自然选择的生物进化过程,搜索电力系统连锁故障风险较大的路径,模拟系统在不同初始状态下的可能连锁故障。实际算例表明,该算法可快速模拟电力系统连锁故障,发现系统薄弱环节并发出故障预警,从而进一步为连锁故障阻断对策制定及电网调度提供辅助支持。

  10. 无人机空中加油自主会合导引律研究%Study on guidance law for UAV autonomous rendezvous in aerial refueling

    Institute of Scientific and Technical Information of China (English)

    许萌; 杨朝星

    2014-01-01

    With the theory research of UAV autonomous guidance law for rendezvous in aerial refueling,the problem of homing guidance with impact final heading constraint is put forward.By redesigning the biased item in the 3D space and viewing the desired rendezvous point as the target and combing with pure tracking in the end of the guidance,the requirement for the terminal heading heading is achieved.Finllay,the guidance law given in the article is proved to be reasonable with a simulation example of air-tanker with constant speed and direction and with U motor,the UAV to select different initial position and heading.The simulation results show that the design of autonomous rendezvous guidance law is effective for UAV aerial refueling autonomous rendezvous, solves the existing class of autonomous rendezvous guidance law design complex, to be known in advance tankers trajectory and a large number of online programming calculation.%针对自主空中加油技术中的会和阶段的理论研究,提出一种带有终端偏航角约束的导引问题。通过对三维空间中重新设计偏置项,来同时约束俯仰与偏航角,将期望的会合点作为跟踪目标,并在制导末端结合纯追踪法,实现终端航向的控制。最后,以匀速直线运动和作U型机动的加油机为例,对无人机(UAV)选取不同的初始位置和航向来检验所提出的制导律实现会合的能力。仿真结果表明,所设计的自主会合制导律有效实现无人机空中加油自主会合,解决了现有一类自主会合制导律设计复杂、需预先已知加油机轨迹及大量在线规划计算的问题。

  11. Outage Performance for Heterogeneous Cellular Networks with Interference Cancellation%基于干扰消除的异构蜂窝网络中断分析

    Institute of Scientific and Technical Information of China (English)

    宋康; 韦磊; 冀保峰; 王雅芳; 黄永明; 杨绿溪

    2016-01-01

    Inheterogeneous cellular networks, small cells provide for the handover of users from the macro cell and organize itself during the transmission. This paper studies the downlink outage performance of heterogeneous cellular networks with an interference cancellation scheme employed at macro base station, which aims to eliminate the cross-tier interference from macro base station to small cell users. Then, the downlink performance of heterogeneous cellular networks is investigated. Expressions of the Probability Density Function (PDF) and Cumulative Distribution Function (CDF) of the received SNRs of both macro and small cell users are derived and closed-form expressions of overall outage probability of the system are provided. Both analytical results and simulations show that the overall performance of the heterogeneous cellular networks is improved with interference cancellation.%在异构网络中,小小区可以为宏基站用户提供接入服务,并能够根据自身条件调节传输参数。该文研究在宏基站端干扰消除技术,来消除宏基站到小小区用户的干扰。该文分析了采用此种方案后异构网络下行链路的整体性能,推导了宏基站和小小区用户接收端信噪比的概率密度函数和分布函数。在此基础上,得到了系统整体中断概率的闭合表达式。理论推导和仿真结果表明,干扰消除方案能够有效提升异构蜂窝网络的整体性能。

  12. Valsalva maneuver: shortest optimal expiratory strain duration

    Directory of Open Access Journals (Sweden)

    Ramesh K. Khurana, Md

    2011-07-01

    Full Text Available Purpose : To quantitate the level of difficulty and determine consistency of hemodynamic responses with various expiratory strain (ES durations. Methods : Thirty-four healthy subjects performed the Valsalva maneuver (VM with an ES duration of 10, 12, and 15 seconds in random order. Level of difficulty after each trial was rated 1 to 10, with 10 being the most difficult. Blood pressure and heart rate (HR were recorded continuously and non-invasively. Parameters studied were Valsalva ratio (VR, early phase II (IIE, late phase II (IIL, tachycardia latency (TL, bradycardia latency (BL, and overshoot latency (OV-L. Consistency of responses was calculated. Results : Difficulty increased significantly with increased ES duration: 5.1±0.1 (mean±SEM at 10 seconds, 5.9±0.1 at 12 seconds, and 6.8±0.1 at 15 seconds (p<0.001. Phase IIE, TL, BL, OV-L, and VR response did not differ statistically with increasing ES durations, and there were no differences in variability. Phase IIL response increased significantly with increasing ES duration. Phase IIL was poorly delineated in 14 of 102 trials with 10 seconds ES duration. Conclusions : ES duration of 10 seconds created a low level of difficulty in healthy individuals. This strain duration produced consistent hemodynamic response for all parameters tested except IIL phase. The absence of IIL phase with 10 seconds ES should not be interpreted as an indicator of sympathetic vasoconstrictor failure.

  13. Wage effects of unemployment duration and frequency

    NARCIS (Netherlands)

    van Dijk, J.; Folmer, H

    This paper analyzes the wage effects of unemployment duration and frequency for different regional labor market situations in The Netherlands using a simultaneous equations approach. The main finding is that unemployment duration has a significant negative effect and the frequency of unemployment a

  14. Word Durations in Non-Native English

    Science.gov (United States)

    Baker, Rachel E.; Baese-Berk, Melissa; Bonnasse-Gahot, Laurent; Kim, Midam; Van Engen, Kristin J.; Bradlow, Ann R.

    2010-01-01

    In this study, we compare the effects of English lexical features on word duration for native and non-native English speakers and for non-native speakers with different L1s and a range of L2 experience. We also examine whether non-native word durations lead to judgments of a stronger foreign accent. We measured word durations in English paragraphs read by 12 American English (AE), 20 Korean, and 20 Chinese speakers. We also had AE listeners rate the `accentedness' of these non-native speakers. AE speech had shorter durations, greater within-speaker word duration variance, greater reduction of function words, and less between-speaker variance than non-native speech. However, both AE and non-native speakers showed sensitivity to lexical predictability by reducing second mentions and high frequency words. Non-native speakers with more native-like word durations, greater within-speaker word duration variance, and greater function word reduction were perceived as less accented. Overall, these findings identify word duration as an important and complex feature of foreign-accented English. PMID:21516172

  15. Developing Project Duration Models in Software Engineering

    Institute of Scientific and Technical Information of China (English)

    Pierre Bourque; Serge Oligny; Alain Abran; Bertrand Fournier

    2007-01-01

    Based on the empirical analysis of data contained in the International Software Benchmarking Standards Group(ISBSG) repository, this paper presents software engineering project duration models based on project effort. Duration models are built for the entire dataset and for subsets of projects developed for personal computer, mid-range and mainframeplatforms. Duration models are also constructed for projects requiring fewer than 400 person-hours of effort and for projectsre quiring more than 400 person-hours of effort. The usefulness of adding the maximum number of assigned resources as asecond independent variable to explain duration is also analyzed. The opportunity to build duration models directly fromproject functional size in function points is investigated as well.

  16. Dynamic modeling of a hose-drogue aerial refueling system and integral sliding mode backstepping control for the hose whipping phenomenon

    Directory of Open Access Journals (Sweden)

    Wang Haitao

    2014-08-01

    Full Text Available Dynamic modeling of a hose-drogue aerial refueling system (HDARS and an integral sliding mode backstepping controller design for the hose whipping phenomenon (HWP during probe-drogue coupling are studied. Firstly, a dynamic model of the variable-length hose-drogue assembly is built for the sake of exploiting suppression methods for the whipping phenomenon. Based on the lumped parameter method, the hose is modeled by a series of variable-length links connected with frictionless joints. A set of iterative equations of the hose’s three-dimensional motion is derived subject to hose reeling in/out, tanker motion, gravity, and aerodynamic loads accounting for the effects of steady wind, atmospheric turbulence, and tanker wake. Secondly, relying on a permanent magnet synchronous motor and high-precision position sensors, a new active control strategy for the HWP on the basis of the relative position between the tanker and the receiver is proposed. Considering the strict-feedback configuration of the permanent magnet synchronous motor, a rotor position control law based on the backstepping method is designed to insure global stability. An integral of the rotor position error and an exponential sliding mode reaching law of the current errors are applied to enhance control accuracy and robustness. Finally, the simulation results show the effectiveness of the proposed model and control laws.

  17. Comparative Study on Various Geometrical Core Design of 300 MWth Gas Cooled Fast Reactor with UN-PuN Fuel Longlife without Refuelling

    Science.gov (United States)

    Dewi Syarifah, Ratna; Su'ud, Zaki; Basar, Khairul; Irwanto, Dwi

    2017-07-01

    Nuclear power has progressive improvement in the operating performance of exiting reactors and ensuring economic competitiveness of nuclear electricity around the world. The GFR use gas coolant and fast neutron spectrum. This research use helium coolant which has low neutron moderation, chemical inert and single phase. Comparative study on various geometrical core design for modular GFR with UN-PuN fuel long life without refuelling has been done. The calculation use SRAC2006 code both PIJ calculation and CITATION calculation. The data libraries use JENDL 4.0. The variation of fuel fraction is 40% until 65%. In this research, we varied the geometry of core reactor to find the optimum geometry design. The variation of the geometry design is balance cylinder; it means that the diameter active core (D) same with height active core (H). Second, pancake cylinder (D>H) and third, tall cylinder (D

  18. Dynamic modeling of a hose-drogue aerial refueling system and integral sliding mode backstepping control for the hose whipping phenomenon

    Institute of Scientific and Technical Information of China (English)

    Wang Haitao; Dong Xinmin; Xue Jianping; Liu Jiaolong

    2014-01-01

    Dynamic modeling of a hose-drogue aerial refueling system (HDARS) and an integral sliding mode backstepping controller design for the hose whipping phenomenon (HWP) during probe-drogue coupling are studied. Firstly, a dynamic model of the variable-length hose-drogue assembly is built for the sake of exploiting suppression methods for the whipping phenomenon. Based on the lumped parameter method, the hose is modeled by a series of variable-length links connected with frictionless joints. A set of iterative equations of the hose’s three-dimensional motion is derived subject to hose reeling in/out, tanker motion, gravity, and aerodynamic loads accounting for the effects of steady wind, atmospheric turbulence, and tanker wake. Secondly, relying on a permanent magnet synchronous motor and high-precision position sensors, a new active control strategy for the HWP on the basis of the relative position between the tanker and the receiver is proposed. Considering the strict-feedback configuration of the permanent magnet synchronous motor, a rotor position control law based on the backstepping method is designed to insure global stability. An integral of the rotor position error and an exponential sliding mode reaching law of the current errors are applied to enhance control accuracy and robustness. Finally, the simulation results show the effectiveness of the proposed model and control laws.

  19. Segmental duration in Parkinsonian French speech.

    Science.gov (United States)

    Duez, Danielle

    2009-01-01

    The present study had 2 main objectives: (1) examine the effect of Parkinson's disease (PD) on vowel and consonant duration in French read speech and (2) investigate whether the durational contrasts of consonants and vowels are maintained or compromised. The data indicated that the consonant durations were shortened in Parkinsonian speech (PS), compared to control speech (CS). However, this shortening was consonant dependent: unvoiced occlusives and fricatives were significantly shortened compared to other consonant categories. All vowels were slightly longer in PS than in CS, however, the observed differences were below the level of significance. Despite significant shortening of some consonant categories, the general pattern of intrinsic duration was maintained in PS. There was slightly less agreement for vowels with the normal contrast of intrinsic durations, possibly because vowel durational contrasts are more sensitive to PD disorders. Most PD patients tended to maintain the intrinsic duration contrasts of both vowels and consonants, suggesting that low-level articulatory constraints operate in a similar way and with the same weight in PS and CS. Copyright 2009 S. Karger AG, Basel.

  20. Unemployment Duration over the Business Cycle

    DEFF Research Database (Denmark)

    Rosholm, Michael

    1996-01-01

    In this paper I study the way in which individual unemployment durations vary over the business cycle, as measured by the aggregate unemployment rate. I decompose the cyclical variations in observed unemployment durations into a composition al and a general part. The compositional part consists...... of variations in observed as well as unobserved average individual-specific heterogeneity amongst those flowing into unemployment. The main finding is that the major part (but not all) of the variations in unemployment durations is caused by variations in macroeconomic conditions (i.e. in the aggregate...... unemployment rate) rathan than by changes in the composition of those becoming unemployed....

  1. Computer use, sleep duration and health symptoms

    DEFF Research Database (Denmark)

    Nuutinen, Teija; Roos, Eva; Ray, Carola

    2014-01-01

    and Denmark in 2010, including data on 5,402 adolescents (mean age 15.61 (SD 0.37), girls 53 %). Symptoms assessed included feeling low, irritability/bad temper, nervousness, headache, stomachache, backache, and feeling dizzy. We used structural equation modeling to explore the mediating effect of sleep...... duration on the association between computer use and symptom load. RESULTS: Adolescents slept approximately 8 h a night and computer use was approximately 2 h a day. Computer use was associated with shorter sleep duration and higher symptom load. Sleep duration partly mediated the association between...

  2. A Comprehensive Outage Management Model Based on Multi-Objective Decision Analysis%多目标决策分析的电网综合停电管理模型

    Institute of Scientific and Technical Information of China (English)

    郇嘉嘉; 王钢; 李海锋; 汪隆君

    2013-01-01

    针对目前电网综合停电管理中存在的工作量大和效率低下等问题,综合考虑计划停电、临时停电、故障停电、抢修停电、停电施工等各因素造成停电的电网设备,提出电网综合停电管理多目标多约束决策分析模型。该模型以全部待停电设备具体停电时段的排列组合为决策变量,以电网运行方式、供电可靠性要求、运行维护资源配置和停电时间协调情况为约束条件,以电网经济性、可靠性、工作量均衡性联合最优为目标。计算过程采用基于精英保留策略和目标函数值排序的多目标差分进化算法,高效求取全局 Pareto 前沿最优解集,生成多种可选方案,提供给电力企业进行对比分析和最终决策。以RBTS-BUS6为例进行分析计算,验证了所提模型的合理性和有效性。%In allusion to the heavy workload and inefficiency in comprehensive outage management of power grids, synthetically considering shutdown of power equipments caused by outage due to maintenance schedule, temporary outage, outage caused by faults, outage due to rush-repair, outage under construction and so on a multi-objective and multi-restriction decision analysis model for comprehensive outage management of power grid is proposed. In the proposed model, the permutations and combinations of concrete outage time intervals of all power equipments to be interrupted are taken as decision variables;the operation modes of power grid, the requirement on power supply reliability, the resource allocation for operation and maintenance and the coordination of outage time are taken as constraints; the joint optimization of economy, reliability and workload balance of power grid is taken as the objective. In the computation the multi-objective differential evolution algorithm based on elitism strategy and sorting of objective function values is utilized to achieve global Pareto frontier optimum solution set efficiently

  3. Evidence that gestation duration and lactation duration are coupled traits in primates.

    Science.gov (United States)

    Dubman, Evgenia; Collard, Mark; Mooers, Arne Ø

    2012-12-23

    Gestation duration and lactation duration are usually treated as independently evolving traits in primates, but the metabolic theory of ecology (MTE) suggests both durations should be determined by metabolic rate. We used phylogenetic generalized least-squares linear regression to test these different perspectives. We found that the allometries of the durations are divergent from each other and different from the scaling exponent predicted by the MTE (0.25). Gestation duration increases much more slowly (0.06 switch from gestation to lactation in relation to some as-yet-unidentified body-size-related factor.

  4. Model-Checking Discrete Duration Calculus

    DEFF Research Database (Denmark)

    Hansen, Michael Reichhardt

    1994-01-01

    Duration calculus was introduced by Chaochen Zhou et al. (1991) as a logic to specify and reason about requirements for real-time systems. It is an extension of interval temporal logic where one can reason about integrated constraints over time-dependent and Boolean valued states without explicit...... mention of absolute time. Several major case studies have shown that duration calculus provides a high level of abstraction for both expressing and reasoning about specifications. Using timed automata one can express how real-time systems can be constructed at a level of detail which is close to an actual...... implementation. We consider in the paper the correctness of timed automata with respect to duration calculus formulae. For a subset of duration calculus, we show that one can automatically verify whether a timed automaton ℳ is correct with respect to a formula 𝒟, abbreviated ℳ|=𝒟, i.e. one...

  5. Model-Checking Discrete Duration Calculus

    DEFF Research Database (Denmark)

    Hansen, Michael Reichhardt

    1994-01-01

    Duration calculus was introduced by Chaochen Zhou et al. (1991) as a logic to specify and reason about requirements for real-time systems. It is an extension of interval temporal logic where one can reason about integrated constraints over time-dependent and Boolean valued states without explicit...... mention of absolute time. Several major case studies have shown that duration calculus provides a high level of abstraction for both expressing and reasoning about specifications. Using timed automata one can express how real-time systems can be constructed at a level of detail which is close to an actual...... implementation. We consider in the paper the correctness of timed automata with respect to duration calculus formulae. For a subset of duration calculus, we show that one can automatically verify whether a timed automaton ℳ is correct with respect to a formula 𝒟, abbreviated ℳ|=𝒟, i.e. one...

  6. Long Duration Space Shelter Shielding Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Physical Sciences Inc. (PSI) has developed fiber reinforced ceramic composites for radiation shielding that can be used for external walls in long duration manned...

  7. Multi-Timescale Cascading Outage Model Considering Generator Excitation Protection and OLTC%考虑发电机励磁保护和OLTC的多时间尺度连锁故障模型

    Institute of Scientific and Technical Information of China (English)

    姚锐; 黄少伟; 刘锋

    2015-01-01

    Voltage and reactive power characteristics play an important role in cascading outages and blackouts in power systems. In this paper, a multi-timescale cascading outage model considering on-load tap changer (OLTC) and generator excitation protection was proposed. This model proposed a multi-timescale cascading outage simulation framework, in which clear expression of time in cascading outage simulation was realized, thus overcame limitation of traditional models. Modeling of generator excitation protection and OLTC simulation were introduced in this model. The IEEE-30 system case studies analyzed mechanisms of generator excitation protection and OLTC, and their influence on cascading outage risk and process. Moreover, phrasal characteristics of cascading outages are analyzed using this model.%世界范围内多次连锁故障和大停电事故表明,无功电压相关因素对连锁故障具有重要影响。提出了一种计及有载调压变压器(on-load tap changer,OLTC)和发电机励磁保护的多时间尺度大停电模型。该模型提出了对无功电压具有重要影响的发电机励磁保护和OLTC动作的建模方法,并进一步基于该模型提出了多时间尺度连锁故障模拟方法,实现了连锁故障动态过程的清晰描述,克服了传统连锁故障模型在此方面的局限性。文中用IEEE 30节点系统进行了连锁故障仿真计算,分析了发电机励磁保护、OLTC动作等与无功电压密切相关的因素对连锁故障的影响及机理,并揭示了连锁故障的若干阶段性特征。

  8. Strong motion duration and earthquake magnitude relationships

    Energy Technology Data Exchange (ETDEWEB)

    Salmon, M.W.; Short, S.A. [EQE International, Inc., San Francisco, CA (United States); Kennedy, R.P. [RPK Structural Mechanics Consulting, Yorba Linda, CA (United States)

    1992-06-01

    Earthquake duration is the total time of ground shaking from the arrival of seismic waves until the return to ambient conditions. Much of this time is at relatively low shaking levels which have little effect on seismic structural response and on earthquake damage potential. As a result, a parameter termed ``strong motion duration`` has been defined by a number of investigators to be used for the purpose of evaluating seismic response and assessing the potential for structural damage due to earthquakes. This report presents methods for determining strong motion duration and a time history envelope function appropriate for various evaluation purposes, for earthquake magnitude and distance, and for site soil properties. There are numerous definitions of strong motion duration. For most of these definitions, empirical studies have been completed which relate duration to earthquake magnitude and distance and to site soil properties. Each of these definitions recognizes that only the portion of an earthquake record which has sufficiently high acceleration amplitude, energy content, or some other parameters significantly affects seismic response. Studies have been performed which indicate that the portion of an earthquake record in which the power (average rate of energy input) is maximum correlates most closely with potential damage to stiff nuclear power plant structures. Hence, this report will concentrate on energy based strong motion duration definitions.

  9. Satellite-Based Sunshine Duration for Europe

    Directory of Open Access Journals (Sweden)

    Bodo Ahrens

    2013-06-01

    Full Text Available In this study, two different methods were applied to derive daily and monthly sunshine duration based on high-resolution satellite products provided by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT Satellite Application Facility on Climate Monitoring using data from Meteosat Second Generation (MSG SEVIRI (Spinning Enhanced Visible and Infrared Imager. The satellite products were either hourly cloud type or hourly surface incoming direct radiation. The satellite sunshine duration estimates were not found to be significantly different using the native 15-minute temporal resolution of SEVIRI. The satellite-based sunshine duration products give additional spatial information over the European continent compared with equivalent in situ-based products. An evaluation of the satellite sunshine duration by product intercomparison and against station measurements was carried out to determine their accuracy. The satellite data were found to be within ±1 h/day compared to high-quality Baseline Surface Radiation Network or surface synoptic observations (SYNOP station measurements. The satellite-based products differ more over the oceans than over land, mainly because of the treatment of fractional clouds in the cloud type-based sunshine duration product. This paper presents the methods used to derive the satellite sunshine duration products and the performance of the different retrievals. The main benefits and disadvantages compared to station-based products are also discussed.

  10. Collective behaviors of book holding durations

    Science.gov (United States)

    Li, Ren-De; Guo, Qiang; Han, Jing-Ti; Liu, Jian-Guo

    2016-10-01

    Duration can directly reflect the collective reading behaviors of library user book holding. In this paper, by introducing the burstiness and memory coefficients, we empirically investigate the collective book holding behavior of three university libraries. The statistical results show that there are similar properties among the students with different backgrounds, presenting the burstiness = - 0.2 and memory = 0.5 for three datasets, which indicates that memory and random effects coexist in student book holding durations. In addition, we analyze the behavior patterns without duplicate durations by merging a series of books borrowed and returned at the same time. The results show the average burstiness B increases to -0.16 and memory M drops to 0.16 for three datasets, which indicates that both duplicate behavior and student's preference affect the memory effect. Furthermore, we present a model which assumes student's next book holding duration follows the previous one with probability p, and with probability 1 - p, the student would hold the book independently. The experimental results show that the presented model can reproduce the burstiness and memory effect of student book holding durations when p = 0.5 for empirical datasets and p = 0.2 for de-duplicate datasets, which indicate that the student's preferential holding behavior occurs with the probability p. This work helps in deeply understanding the regularity of duration-based human behaviors.

  11. Call Duration Characteristics based on Customers Location

    Directory of Open Access Journals (Sweden)

    Žvinys Karolis

    2014-05-01

    Full Text Available Nowadays a lot of different researches are performed based on call duration distributions (CDD analysis. However, the majority of studies are linked with social relationships between the people. Therefore the scarcity of information, how the call duration is associated with a user's location, is appreciable. The goal of this paper is to reveal the ties between user's voice call duration and the location of call. For this reason we analyzed more than 5 million calls from real mobile network, which were made over the base stations located in rural areas, roads, small towns, business and entertainment centers, residential districts. According to these site types CDD’s and characteristic features for call durations are given and discussed. Submitted analysis presents the users habits and behavior as a group (not an individual. The research showed that CDD’s of customers being them in different locations are not equal. It has been found that users at entertainment, business centers are tend to talk much shortly, than people being at home. Even more CDD can be distorted strongly, when machinery calls are evaluated. Hence to apply a common CDD for a whole network it is not recommended. The study also deals with specific parameters of call duration for distinguished user groups, the influence of network technology for call duration is considered.

  12. 机动车加油过程中气液两相流动特性的CFD数值模拟%CFD Numerical Simulation onto the Gas-Liquid Two-Phase Flow Behavior During Vehicle Refueling Process

    Institute of Scientific and Technical Information of China (English)

    陈家庆; 张男; 王金惠; 朱玲; 尚超

    2011-01-01

    With the gradual improvement of environmental regulations,more and more attentions are attracted to the vapor emissions during the process of vehicle refueling.Research onto the vehicle refueling process by means of numerical simulation has been executed abroad since 1990s,while as it has never been involved so far domestically.Through reasonable simplification about the physical system of "Nozzle + filler pipe+ gasoline storage tank + vent pipe" for vehicle refueling,and by means of volume of fluid(VOF) model for gas-liquid two-phase flow and Re-Normalization Group k-ε turbulence flow model provided in commercial computational fluid dynamics(CFD) software Fluent,this paper determined the proper mesh discretization scheme and applied the proper boundary conditions based on the Gambit software,then established the reasonable numerical simulation model for the gas-liquid two-phase flow during the refueling process.Through discussing the influence of refueling velocity on the static pressure of vent space in gasoline tank,the back-flowing phenomenon has been revealed in this paper.It has been demonstrated that,the more the flow rate and the refueling velocity of refueling nozzle is,the higher the gross static pressure in the vent space of gasoline tank.In the meanwhile,the variation of static pressure in the vent space of gasoline tank can be categorized into three obvious stages.When the refueling flow rate becomes higher,the back-flowing phenomenon of liquid gasoline can sometimes be induced in the head section of filler pipe,thus making the gasoline nozzle pre-shut-off.Totally speaking,the theoretical work accomplished in this paper laid some solid foundation for self-researching and self-developing the technology and apparatus for the vehicle refueling and refueling emissions control domestically.%随着环保法规的不断完善,机动车加油过程中所产生的油气排放污染问题越来越受到重视.国外自20世纪90年代中后

  13. 一种配电网线路不停电融冰方法%A Non-outage De-icing Method of Distribution Lines

    Institute of Scientific and Technical Information of China (English)

    杨少杰; 高一波

    2016-01-01

    A non-outage de-icing method of distribution lines is proposed. By lowering operating voltage of the iced distribution lines and increasing the current of the iced lines, the ice is melted by heat. A pair of wide-range on-load tap changer transformers are connected in series with both terminals of the iced lines through switches. By adjustment of the two transformers, the operating voltage of the iced lines is lowered to ensure voltage stability at the load terminal. A simulation model of non-outage deicing system of distribution lines is established based on PSCAD platform to simulate and analyze line deicing under different operating condi-tions; besides, the various reactive power compensation schemes are compared to provide voltage support for lines. In the end, the application scenario of the scheme is expounded.%提出了一种配网线路不停电融冰的方法,通过降低配电网线路覆冰段的运行电压、增加覆冰段线路电流,以实现热力融冰。将2台大范围有载调压变压器通过开关装置串联接入线路覆冰段两端,通过这2台融冰变压器的协同调节降低线路覆冰段运行电压,并保证负荷端电压的稳定。基于PSCAD平台搭建了配电网线路不停电融冰系统仿真模型,对不同工况下的线路融冰运行情况进行了仿真分析,并对不同无功补偿方案进行对比分析,从而为线路提供电压支撑,最后给出了该方案的适用场合。

  14. Formation flight control for unmanned air vehicle during aerial refueling%无人机空中加油过程中编队飞行控制

    Institute of Scientific and Technical Information of China (English)

    黄红建; 袁锁中; 戴文正

    2014-01-01

    针对空中加油中无人机位置保持问题,进行了时变质量UAV的动力学建模与非线性控制设计。综合考虑了燃油传输对UAV的质量、惯性矩阵和质心位置的影响,基于相对于惯性系的状态变量,推导了UAV时变质量动力学方程。分析燃油传输带来的动力学影响,并设计神经网络动态逆控制律来实现UAV的位置保持,通过非线性仿真验证了控制律的有效性。%To keep the position of an unmanned air vehicle (UAV) during autonomous aerial refueling, we develop the dynamic model and put forward a nonlinear controller for the UAV with time-varying mass. By comprehensively considering the effect of fuel transfer on the UAV mass, the inertia matrix and the center of mass, we derive the time-varying mass dynamic equations of UAV based on state variables relative to inertial reference frame. Through analyzing the dynamic characteristic effect of fuel transfer, we design neural network dynamic inversion control law to keep the position of unmanned air vehicle, and nonlinear simulation demonstrates the effectiveness of the flight control law.

  15. LiquidPower-1. Development and proof-of-concept of core methanol reformer for stationary and motive fuel cell systems and hydrogen refuelling stations. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Krogsgaard, J.; Mortensen, Henrik [H2 Logic A/S, Herning (Denmark); Skipper, T. [Dantherm Power A/S, Hobro (Denmark)

    2013-03-15

    LiquidPower-1 has developed laboratory test systems for methanol reforming and tested reformers from four different suppliers. This has contributed to determining the state-of-the-art level for methanol reforming and enabled an update of the LiquidPower R and D Roadmap onwards a commercialisation of the technology. The project has achieved the following results: 1) A detailed technical specification of methanol reformers for the fuel cell back-up power and hydrogen refueling station markets has been conducted; 2) Laboratory test systems for methanol reformers has been developed and established at Dantherm Power and H2 Logic; 3) Initial test of reformers from four suppliers has been conducted - with two suppliers being selected for continued tests; 4) Extensive laboratory tests conducted of reformers from two suppliers, with the aim to determine state-of-the-art for price, efficiency, capacity and lifetime. Several errors and break-downs were experienced during the test period, which revealed a need for further R and D to improve lifetime and stability; 5) The LiquidPower F and U Roadmap has been updated. Reformer TCO targets (Total Cost of Operation) for each of the markets have been calculated including updated targets for efficiency and cost. These targets also serve as the main ones to be pursued as part of the continued R and D roadmap execution. Compared to the previous edition of the Roadmap, the project has confirmed the viability of methanol reforming, but also revealed that stability and lifetime needs to be addressed and solved before commencing commercialization of the technology. If the Roadmap is successful a commercialization can commence beyond 2015. (Author)

  16. Study of a transaugmented two-stage small circular-bore railgun for injection of hypervelocity hydrogen pellets as a fusion reactor refueling mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Tompkins, M.W.; Anderson, M.A.; Feng, Q.; Zhang, J.; Kim, K. [Univ. of Illinois, Urbana, IL (United States)

    1997-01-01

    Injection of hypervelocity hydrogen pellets has become widely accepted as the most effective means of refueling magnetically confined fusion reactors. Pellet velocities on the order of 10 km/s are desired and hydrogen pellet erosion during acceleration must be minimized. It is important to maintain uniform bore surfaces during repetitive shots, implying that, if a railgun is to be used to accelerate the pellets, damage to the sidewalls and rails of the railgun due to local heating must be limited. In order to reduce the amount of power dissipated within the bore and increase the propulsive force generated by the plasma-arc armature while minimizing losses due to pellet, rail, and sidewall ablation, the authors have employed a magnetic field transaugmentation mechanism consisting of a two-turn pulsed electromagnet. The two-stage gun consists of a light-gas gun which accelerates a 4- to 5-mg pellet to a speed around 1.2 km/s and injects it into the plasma-arc armature railgun. Currently, they have achieved a final output velocity for a hydrogen pellet of 2.11 km/s with a time-averaged acceleration of 4,850 km/s{sup 2} using a 58-cm railgun pulsed with a peak rail current of 9.2 kA and 28.0 kA of transaugmentation current. This paper will present a description of the hydrogen-pellet-injector railgun system, a discussion of the data on hydrogen pellet acceleration, and projections for future systems.

  17. 电网停电综合管理与分析决策系统的研究与开发%Study and development of outage comprehensive management and analysis decision system for power grids

    Institute of Scientific and Technical Information of China (English)

    郇嘉嘉; 王钢; 李海锋; 汪隆君; 李平

    2012-01-01

    针对电力企业在停电管理中存在的不足与业务需求,提出了电网停电综合管理与分析决策系统物理构架、逻辑构架与功能的设计思路.基于电网最优综合停电模型的理论体系,采用Java企业应用平台对系统进行了开发.该系统从电网运行方式、负荷水平、运维资源配置等实际情况出发,以电网经济性与可靠性综合效益最优为目标,通过对停电计划的定量分析、评价和比较,自动生成最优决策方案,并具有停电计划关联自动提醒、工作量均衡分析、停电计划辅助更新以及停电设备分析评估等功能.该系统的试点运行效果充分表明其不仅能够为停电计划编制提供强有力的技术支持,还为提高各部门协同运作效率、提升客户服务层次奠定了坚实的业务基础,具有极大的理论研究意义和工程应用价值.%According to the deficiencies and business requirements in outage management process of power enterprises, this paper proposes the design ideas of the physical structure, logic structure and function modules for the outage comprehensive management and analysis decision system. Based on the theoretical system of comprehensive optimal outage model, this paper adopts the technology of Java Platform Enterprise Edition to develop the system. Considering the actual conditions of the power grids operation, load level, resource allocation and so on, the system takes comprehensive benefits of power grids economy and reliability as the optimizing objective. By quantitative analysis, evaluation and comparison of outage schedules, it makes the optimal outage scheduling automatically with the functions of automated association and reminder for outage schedules, equilibrium analysis for workload, assistant update, analysis and evaluation for outage equipments and so on. The operation effect of the system in pilot areas fully proves that it can not only provide strong technical support to plan

  18. 200 MW Thermal Power Plant Unit Film-forming Amines Outage Protection Method Application%200MW机组成膜胺停炉保护方法应用

    Institute of Scientific and Technical Information of China (English)

    李朝燕

    2013-01-01

    介绍几种常用停炉保护方法,结合实例从实验室试验、现场实施、汽水品质监控三方面分析成膜胺停炉保护方法的应用情况,说明应用效果,并提出应用中的注意事项。%This paper introduces several common outage pro-tection methods ,analyzes the application condition of film-forming amines outage protection method through the laboratory experiment ,field implementation ,water and steam quality mo-nitoring ,and illustrates the application effect ,and puts forward attentions should be mentioned during application .

  19. Sociosexuality, Morningness–Eveningness, and Sleep Duration

    Directory of Open Access Journals (Sweden)

    Christoph Randler

    2016-01-01

    Full Text Available Morningness–eveningness is the preference for different times of day for activity and sleep. Here, we addressed the effects of sleep behavior and morningness–eveningness on sociosexuality. Three hundred students (M age = 22.75 years, with 95% between 18 and 28 participated online, answering questions about morningness–eveningness (rMEQ [Reduced Morningness–Eveningness Questionnaire], midpoint of sleep on free days (MSF, sleep duration, and the Sociosexuality Orientation Inventory–Revised (SOI-R. The SOI-R contains three subscales, Behavior, Attitude, and Desire. Evening orientation and short sleep duration were related to a higher total SOI-R and to the three subscales. Based on the linear models, the strongest effect on sociosexuality was produced by gender (27% explained variance while age accounted for 6% of variance. Nonadditive variance explained by sleep–wake behavior was 7% (MSF, 4% (sleep duration, and 4% (rMEQ scores; 3% rMEQ-based typology. Older age was related to less-restricted sociosexuality, and men were less restricted than women in Attitude and Desire. Sleep duration and rMEQ scores were associated with Attitude and Desire; but only MSF was significantly related to Behavior. The data show that sleep–wake variables are associated with sociosexuality, with evening orientation and shorter sleep duration being related to a less-restricted sociosexuality.

  20. Impact of response duration on multisensory integration

    Science.gov (United States)

    Barnett, Zachary P.; Wallace, Mark T.

    2012-01-01

    Multisensory neurons in the superior colliculus (SC) have been shown to have large receptive fields that are heterogeneous in nature. These neurons have the capacity to integrate their different sensory inputs, a process that has been shown to depend on the physical characteristics of the stimuli that are combined (i.e., spatial and temporal relationship and relative effectiveness). Recent work has highlighted the interdependence of these factors in driving multisensory integration, adding a layer of complexity to our understanding of multisensory processes. In the present study our goal was to add to this understanding by characterizing how stimulus location impacts the temporal dynamics of multisensory responses in cat SC neurons. The results illustrate that locations within the spatial receptive fields (SRFs) of these neurons can be divided into those showing short-duration responses and long-duration response profiles. Most importantly, discharge duration appears to be a good determinant of multisensory integration, such that short-duration responses are typically associated with a high magnitude of multisensory integration (i.e., superadditive responses) while long-duration responses are typically associated with low integrative capacity. These results further reinforce the complexity of the integrative features of SC neurons and show that the large SRFs of these neurons are characterized by vastly differing temporal dynamics, dynamics that strongly shape the integrative capacity of these neurons. PMID:22896723

  1. 考虑线路多种停运模式的静态电压稳定风险评估%Risk Assessment of Static Voltage Stability by Considering Multiple Outage Model of Lines

    Institute of Scientific and Technical Information of China (English)

    吴昊; 薛贵挺; 张焰; 杨增辉; 冯煜尧

    2011-01-01

    Due to the common mode outages and dependent outages have great impact on system static voltage stability,this paper focuses on the establishment of the equivalent branch outage model for two parallel transmission lines by considering outage overlapping, then computes the state probability of transmission system. Basing on the state probability model of power system, a risk index system of static voltage stability and the calculation method of every index are presented. By the voltage stability criteria based on CPF and optimal load shedding model, the loss of voltage stability of transmission system can be judged and controlled. Taking an area of power grid for east china for example, the risk of static voltage stability is assessed, which verifies the effectiveness of the proposed method.%鉴于双回平行输电线路共同模式停运和相关停运对系统电压稳定性影响较大,本文重点建立了双回线多种停运模式重叠的支路等效停运模型,进而计算输电系统状态概率.在输电系统状态概率模型的基础上,提出输电系统静态电压稳定风险评估指标体系及各项指标计算方法,其中通过基于连续潮流的电压稳定性判据及最优切负荷模型,对输电系统电压失稳进行判定及校正控制.最后以华东某地区电网为例进行静态电压稳定风险评估,说明本文所提方法的有效性.

  2. Nakagami-m信道下DAF选择中继的中断性能分析%Outage Performance of Selection Decode-and-Forward Relay Network over Nakagami-m Fading Channels

    Institute of Scientific and Technical Information of China (English)

    啜钢; 刘振兴; 王涛

    2011-01-01

    To solve the complicated problem of analysis of outage performance in cooperative communication system, a theoretical analysis method is proposed. A selection relay model with a direct link over independent identically distributed Nakagami-m fading channels is considered based on the power restricted cooperative communication system. An analytical expression of outage probability is derived and the outage performance is analyzed for this model. The optimal power allocation is also investigated and a power allocation factor in a specific relay number is given. Simulations show that the outage performance is evidently improved compared with other selection relay models. The optimal power allocation ia also investigated and a power allocation factor in a specific relay number is given.%为了解决协作通信系统中选择中继算法中断性能分析复杂的问题,提出了一种新的中断分析方法.基于功率受限协作通信系统,考虑Nakagami-m独立同分布信道下一种带有直通链路的选择中继模型,在该模型下推导了中断概率表达式,分析了系统的中断性能,经仿真验证了理论分析的准确性.探讨了优化功率分配,给出特定中继数情况下的功率分配系数.分析结果表明,在该模型下的中断性能与已有模型相比均有所提高.

  3. 基于模糊推理的配电网停电原因分析系统%Distribution Network Outage Cause Analyzing System Based on Fuzzy Inference

    Institute of Scientific and Technical Information of China (English)

    周志宇; 周静; 江东林; 艾欣

    2013-01-01

    针对配电网停电原因复杂、停电研判决策不易等问题,对停电原因进行了深入分析并开发了应用系统.基于停电后其他相关系统可提供的信息及电网自身特点,提出了分层求解方法,并采用模糊外展理论进行了停电原因分析,采用混合架构完成了系统设计与开发,并在生产指挥平台上完成了系统部署.通过在配电网生产抢修指挥中的应用,证明了该系统的有效性和实用性.%To tackle the outage cause identification problem and the difficulty in decision-making for power outage judgment of the distribution system,a distribution network outage cause analyzing system is proposed based on fuzzy inference,and its application system is developed.By drawing on the information provided by related systems and the characteristics of the distribution system itself,a hierarchical solving method and the fuzzy abduction theory are used to analyze the outage causes.The system is completed by using the hybrid architecture and the production is deployed on the production command platform.Application in the command of production and emergency repair shows the system proposed is effective and practical.

  4. DF协作系统中基于中断概率的功率分配算法%Power allocation algorithm based on outage probability for DF cooperative systems

    Institute of Scientific and Technical Information of China (English)

    宋婧; 葛建华; 李靖

    2011-01-01

    Since the equal power allocation (EPA) between the source node and the relay node in the decodeforward (DF) cooperative communication system results in resource inefficiency, a power allocation algorithm based on outage probability analysis is proposed. This algorithm aims to reduce the average outage probability of the system, in which the upper and lower bound expressions for the system average outage probability of the model are derived according to the average signal to noise ratios of the upper link channels of and the channels between users. The power allocation factor that leads to a lower system average outage probability is obtained by the golden section method. Simulation results show that, all conditions being the same, this power allocation scheme can achieve a better performance than the equal power allocation (EPA) scheme.%针对译码转发(DF)协作通信系统中源和中继采用平均功率分配,导致系统资源利用率较低的问题,提出了一种基于中断概率分析的功率分配算法.该算法以降低系统的中断概率为目标,根据用户上行信道和用户间信道的平均信噪比,推导出该模型的系统平均中断概率上下限表达式,并通过黄金分割法迭代出使系统平均中断概率降低的功率分配因子.仿真结果表明,在相同条件下,该功率分配方案比平均功率分配(EPA)方案性能更优.

  5. 中继选择协议下的认知无线电系统性能研究%Research the outage performance of cognitive radio system based on protocols of relay selection

    Institute of Scientific and Technical Information of China (English)

    唐菁敏; 龙华; 邵玉斌; 彭艺

    2012-01-01

    An approximate outage probability formulation were derived for amplify-and-forward with relay selection (SAF), decode-and-forward with relay selection (SDF) protocol and hybrid protocol with relay selection (HPRS) on the premise of guarantee primary user quality of service (QoS) and limit of maximal power in cognitive user. By Monte Carlo simulation, the rationality of the approximate outage probability formulation is validated. Theoretical analysis and simulation results show that the outage probability of three cooperative protocols is closely related to interference limit and maximal power in cognitive user. Meanwhile, the three protocols can achieve the full space diversity and the HPRS outperforms both the SAF and SDF in outage performance.%在保证授权用户服务质量(QoS)和认知用户峰值功率限制的前提下,推导出高信噪比时放大转发中继选择(SAF)协议、解码转发中继选择(SDF)协议和混合中继选择协议(HPRS)下认知中继系统中断概率的近似表达式.Monte Carlo仿真验证了三种协议下中断概率近似表达式的合理性,理论和仿真结果表明,三种协议的中断概率与干扰限制条件和认知用户峰值功率密切相关,且HPRS中断性能要优于SAF和SDF.

  6. Fluctuation behaviors of financial return volatility duration

    Science.gov (United States)

    Niu, Hongli; Wang, Jun; Lu, Yunfan

    2016-04-01

    It is of significantly crucial to understand the return volatility of financial markets because it helps to quantify the investment risk, optimize the portfolio, and provide a key input of option pricing models. The characteristics of isolated high volatility events above certain threshold in price fluctuations and the distributions of return intervals between these events arouse great interest in financial research. In the present work, we introduce a new concept of daily return volatility duration, which is defined as the shortest passage time when the future volatility intensity is above or below the current volatility intensity (without predefining a threshold). The statistical properties of the daily return volatility durations for seven representative stock indices from the world financial markets are investigated. Some useful and interesting empirical results of these volatility duration series about the probability distributions, memory effects and multifractal properties are obtained. These results also show that the proposed stock volatility series analysis is a meaningful and beneficial trial.

  7. [Labor duration: from normality to dystocia].

    Science.gov (United States)

    Kayem, G

    2015-04-01

    "Normal" labor has been surprisingly little studied in the past 60 years even though it is a central axis in obstetrics. Standards were proposed 60 years ago by Emmanuel Friedman and adopted by many countries to become then, driven from Dublin school, the conditions allowing the management of labor: rupture of membranes and oxytocin with, in case of failure for dynamic dystocia, cesarean. Recent data have suggested that labor duration had changed since the 1960s. Changes in women's characteristics and in obstetric practice especially with the widespread use of oxytocin and realization of epidural may have an impact on labor duration. Current studies suggest that it may be possible to authorize longer labor duration without significant increase in maternal or neonatal morbidity. However, it is premature to change practices following the latest American recommendations without prior studies. Copyright © 2015. Published by Elsevier SAS.

  8. Development of linear sensitivity matrix method for fast evaluation of CANDU refuelling schemes%用于CANDU堆换料方案快速评价的线性敏感矩阵方法

    Institute of Scientific and Technical Information of China (English)

    王文聪; 刘宇轩; 冯进军; 王军; 樊申; 张少泓

    2009-01-01

    为了实现CANDU堆换料方案的快速评价,本文提出了线性敏感矩阵方法(LSM).该方法基于各种扰动引起的堆芯状态变化互不干涉且堆芯对扰动的响应与扰动量成正比的假设,借助于事先针对参考堆芯形成的敏感矩阵,主要的堆芯参数经简单代数运算就可得到,无需耗时的三维扩散方程求解.秦山三期1号机组部分运行历史检验结果表明,该方法不但可大幅提高换料方案评价的速度,而且还具有较高的精度,能满足现场工程应用的要求.%In order to develop a numerical tool for the fast evaluation of CANDU refuelling schemes, a Linear Sensitivity Matrix method (LSM) is developed. It assumes that all the effects caused by various perturbations to the core state are independent to each other and the core response to a perturbation is proportional to its magnitude. In this way, the main core parameters of a refuelling scheme can be derived by simple algebraic operations with the use of pre-calculated sensitivity matrices, without resorting to the complicated and time-consuming 3D core calculation. Verification against the QinShan CANDU reactor operation history demonstrates that LSM is capable of generating accurate results and running very fast for evaluating a refuelling scheme.

  9. Slow Wave Sleep and Long Duration Spaceflight

    Science.gov (United States)

    Whitmire, Alexandra; Orr, Martin; Arias, Diana; Rueger, Melanie; Johnston, Smith; Leveton, Lauren

    2012-01-01

    While ground research has clearly shown that preserving adequate quantities of sleep is essential for optimal health and performance, changes in the progression, order and /or duration of specific stages of sleep is also associated with deleterious outcomes. As seen in Figure 1, in healthy individuals, REM and Non-REM sleep alternate cyclically, with stages of Non-REM sleep structured chronologically. In the early parts of the night, for instance, Non-REM stages 3 and 4 (Slow Wave Sleep, or SWS) last longer while REM sleep spans shorter; as night progresses, the length of SWS is reduced as REM sleep lengthens. This process allows for SWS to establish precedence , with increases in SWS seen when recovering from sleep deprivation. SWS is indeed regarded as the most restorative portion of sleep. During SWS, physiological activities such as hormone secretion, muscle recovery, and immune responses are underway, while neurological processes required for long term learning and memory consolidation, also occur. The structure and duration of specific sleep stages may vary independent of total sleep duration, and changes in the structure and duration have been shown to be associated with deleterious outcomes. Individuals with narcolepsy enter sleep through REM as opposed to stage 1 of NREM. Disrupting slow wave sleep for several consecutive nights without reducing total sleep duration or sleep efficiency is associated with decreased pain threshold, increased discomfort, fatigue, and the inflammatory flare response in skin. Depression has been shown to be associated with a reduction of slow wave sleep and increased REM sleep. Given research that shows deleterious outcomes are associated with changes in sleep structure, it is essential to characterize and mitigate not only total sleep duration, but also changes in sleep stages.

  10. Outage Performance Based on Optimal Power Allocation in Cognitive Multi-node Relay Networks%认知多中继网络中基于最佳功率分配的中断性能

    Institute of Scientific and Technical Information of China (English)

    宋耀莲; 酆广增

    2013-01-01

    In this paper,we investigate the power allocation schemes of cognitive multi-node relay networks. A simple optimal power allocation (OPA) method is proposed, and the optimal solution is given. We simulate the outage performance of different location of cognitive relay and investigate spectrum sensing and cognitive multi-node relay cooperative transmission. The numerical results show that the outage performance of optimal power allocation is superior to that of equal power allocation ( EPA). Furthermore, there exists an optimal spectrum sensing time to optimize the outage performance of cognitive multi-node relay networks.%研究了认知多中继网络的功率分配方案,提出了简单的最优功率分配(OPA)方法,并给出最优解.仿真了不同的认知中继位置对认知系统中断性能的影响,并联合考虑频谱感知和认知多中继协作传输两个过程.仿真结果表明,文中提出的最佳功率分配方案的中断性能优于等功率分配(EPA)方案,且存在最佳的感知时间使认知多中继网络的中断性能最优.

  11. Minimization of outage probability of WiMAX link supported by laser link between a high-altitude platform and a satellite.

    Science.gov (United States)

    Arnon, Shlomi

    2009-07-01

    Various technologies for the implementation of a WiMAX (IEEE802.16) base station on board a high-altitude platform (HAP) are currently being researched. The network configuration under consideration includes a satellite, several HAPs, and subscribers on the ground. The WiMAX base station is positioned on the satellite and connects with the HAP via an analog RF over-laser communication (LC) link. The HAPs house a transparent transponder that converts the optic signal to a WiMAX RF signal and the reverse. The LC system consists of a laser transmitter and an optical receiver that need to be strictly aligned to achieve a line-of-sight link. However, mechanical vibration and electronic noise in the control system challenge the transmitter-receiver alignment and cause pointing errors. The outcome of pointing errors is fading of the received signal, which leads to impaired link performance. In this paper, we derive the value of laser transmitter gain that can minimize the outage probability of the WiMAX link. The results indicate that the optimum value of the laser transmitter gain is not a function of the pointing error statistics.

  12. Decontamination equipment for the bottom of the cavity NPP during refueling operations; Equipo para la descontaminacion del fondo de la cavidad de centrales nucleares durante las operaciones de recarga de combustible

    Energy Technology Data Exchange (ETDEWEB)

    Vaquer, J. I.; Pastor, I.; Pascual, A.; Garcia Martinez, A.

    2014-04-01

    In this work the DEMOS robot is displayed, as a designed and developed equipment by Grupo Dominguis in order to carry out the decontamination of the cavity background in Nuclear Power Plants during the refueling operations. the aim of the project is executing the decontamination of the cavity ground, in case of flood pool, by means of brushing and aspirated after the fuel movement operation, in order to reduce the operational dose of the workers. In the activities that are carried out after while in the cavity. Eventually, the obtained results of the operative experience in many Nuclear Power Plants will be displayed. (Author)

  13. LINK2009 Phase 1: Development of 2. generation fuel cell vehicles and hydrogen refueling station. Final report; LINK2009 fase 1: Udvikling af 2. gen. braendselscelle koeretoejer og brinttankstation. Slutrapport

    Energy Technology Data Exchange (ETDEWEB)

    2010-03-15

    LINK2009 project was to develop 2nd gen. technologies fuel cell systems for vehicles and 350bar hydrogen refueling stations. Also the LINK2009 project were to ensure a continuously positioning of Denmark and the Scandinavian Region within hydrogen for transport and continue to attract international car manufacturers to conduct demonstration and later market introduction in the region. The LINK2009 project is divided in two phases where this first phase only deals with the development of the 2nd generation technologies, whereas the following phase 2 will include the demonstration hereof as well as additional research activities. This Report describes the results of the phase 1 that was commenced in summer 2008 and ended in late 2009. Phase 1 has resulted in the development of new 2nd generation fuel cell technology for use in a city car and a service vehicle. Stated targets for price and efficiency have been reached and the following demonstration in Phase 2 is to confirm reaching of life time targets. The efficiency of the fuel cell system for the city car has been measured to be 42-48% at a power delivery of respectively 10kW and 2kW, which is significantly above the target of >40%. System simplifications and selection of new components have enabled a 50% reduction in the kW price for the fuel cell system, including 700bar hydrogen storage, now totalling Euro 4.500/kW. This creates sufficient basis for conducting demonstration of the system in vehicles. 9 vehicles are planned to be demonstrated in the following phase 2. Additional 8 vehicles were put in operation in Copenhagen in November 2009. Phase 1 has conducted development of 2nd gen. hydrogen refuelling technology that has resulted in concepts for both 350bar and 700bar refuelling as well as a concept for onsite hydrogen production at refuelling stations. In separate projects the developed 350bar technology has been brought to use in a newly established hydrogen station in Copenhagen, and the hydrogen

  14. Duration Properties of Timed Transition Systems

    DEFF Research Database (Denmark)

    Liu, Zhiming; Ravn, Anders P.; Li, Xiaoshan

    1997-01-01

    This paper proposes a method for formal real-time systems development.The system requirements and high level design decisions are time interval properties, and are therefore specified in the Duration Calculus (DC), while the implementation and refinement are described in termsof timed transition ...

  15. Preventive maintenance at opportunities of restricted duration

    NARCIS (Netherlands)

    R. Dekker (Rommert); E. Smeitink

    1994-01-01

    textabstractThis article deals with the problem of setting priorities for the execution of maintenance packages at randomly occurring opportunities. These opportunities are of restricted duration, implying that only a limited number of packages can be executed. The main idea proposed is to set up a

  16. 5 CFR 890.1302 - Duration.

    Science.gov (United States)

    2010-01-01

    ... Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL EMPLOYEES HEALTH BENEFITS PROGRAM Department of Defense Federal Employees Health Benefits Program Demonstration Project § 890.1302 Duration. The demonstration project will run from January 1, 2000, through...

  17. Verifying duration properties of timed transition systems

    DEFF Research Database (Denmark)

    Liu, Zhiming; Ravn, Anders P.; Li, Xiaoshan

    1998-01-01

    This paper proposes a method for formal real-time systems development:Requirements and high level design decisions are time interval properties and are therefore specified in the Duration Calculus (DC), while implementations are described bytimed transition systems (TTS). A link from implementati...

  18. Estimating the duration of speciation from phylogenies.

    Science.gov (United States)

    Etienne, Rampal S; Morlon, Hélène; Lambert, Amaury

    2014-08-01

    Speciation is not instantaneous but takes time. The protracted birth-death diversification model incorporates this fact and predicts the often observed slowdown of lineage accumulation toward the present. The mathematical complexity of the protracted speciation model has barred estimation of its parameters until recently a method to compute the likelihood of phylogenetic branching times under this model was outlined (Lambert et al. ). Here, we implement this method and study using simulated phylogenies of extant species how well we can estimate the model parameters (rate of initiation of speciation, rate of extinction of incipient and good species, and rate of completion of speciation) as well as the duration of speciation, which is a combination of the aforementioned parameters. We illustrate our approach by applying it to a primate phylogeny. The simulations show that phylogenies often do not contain enough information to provide unbiased estimates of the speciation-initiation rate and the extinction rate, but the duration of speciation can be estimated without much bias. The estimate of the duration of speciation for the primate clade is consistent with literature estimates. We conclude that phylogenies combined with the protracted speciation model provide a promising way to estimate the duration of speciation.

  19. Breathhold duration and response to marijuana smoke.

    Science.gov (United States)

    Zacny, J P; Chait, L D

    1989-06-01

    Marijuana smokers are frequently observed to hold the smoke in their lungs for prolonged periods (10-15 sec) apparently in the belief that prolonged breathholding intensifies the effects of the drug. The actual influence of breathhold duration on response to marijuana smoke has not been studied. The present study examined the effects of systematic manipulation of breathhold duration on the physiological, cognitive and subjective response to marijuana smoke in a group of eight regular marijuana smokers. Subjects were exposed to each of three breathhold duration conditions (0, 10 and 20 sec) on three occasions, scheduled according to a randomized block design. A controlled smoking procedure was used in which the number of puffs, puff volume and postpuff inhalation volume were held constant. Expired air carbon monoxide levels were measured before and after smoking to monitor smoke intake. Typical marijuana effects (increased heart rate, increased ratings of "high" and impaired memory performance) were observed under each of the breathhold conditions, but there was little evidence that response to marijuana was a function of breathhold duration.

  20. On the Stringing Construction Technology of Transmission Lines Crossing without Power Outage%浅析输电线路不停电跨越架线施工技术

    Institute of Scientific and Technical Information of China (English)

    高玉恒

    2014-01-01

    With the development of economy, electric power industry develops faster and faster and transmission lines increase accordingly. At present, the transmission line is faced with the status that new line crosses with the live line. If power outage is needed to apply for a region, the power construction is very complicated, even if the power outage demand is met, it also needs a long time to carry on the construction, thus affecting the whole power grid construction. In order to solve this problem, the crossing construction technology without power outage arises at the historic moment. Therefore, researchers must analyze and summarize the stringing construction technology of transmission lines crossing without power outage. Combined with work experience for many years, the author makes a brief analysis on the stringing construction technology of transmission lines crossing without power outage from the general method and process of the technology.%随着经济的发展,电力行业发展越来越快,输电线路因此不断增加。目前,我国输电线路面临着新建线路与带电线路交叉跨越的现状,如果某地区需要申请停电,停电施工会非常复杂,即使满足了停电需求,施工也要等待很长一段时间,从而影响整个电网工程建设。为了解决这一难题,不停电跨越施工技术应运而生,因此,研究人员必须对输电线路不停电跨越架线施工技术进行分析和总结。笔者结合多年工作经验,从不停电跨越架线施工的一般方法和流程着手,对输电线路不停电跨越架线施工技术作了简要分析。