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Sample records for checklist optimizes timing

  1. Optimal time discrimination

    OpenAIRE

    Coşkun, Filiz; Sayalı, Zeynep Ceyda; Gürbüz, Emine; Balcı, Fuat

    2015-01-01

    Optimal Time Discrimination Journal: Quarterly Journal of Experimental Psychology Manuscript ID: QJE-STD 14-039.R1 Manuscript Type: Standard Article Date Submitted by the Author: n/a Complete List of Authors: Çoskun, Filiz; Koç University, Psychology Sayalı Ungerer, Zeynep; Koç University, Psychology Gürbüz, Emine; Koç University, Psychology Balcı, Fuat; Koç University, Psychology Keywords: Decision making, Interval Timing, Optimality, Response Times, Temporal ...

  2. Real time production optimization

    Energy Technology Data Exchange (ETDEWEB)

    Saputelli, Luigi; Otavio, Joao; Araujo, Turiassu; Escorcia, Alvaro [Halliburton, Houston, TX (United States). Landmark Division

    2004-07-01

    Production optimization encompasses various activities of measuring, analyzing, modeling, prioritizing and implementing actions to enhance productivity of a field. We present a state-of-the-art framework for optimizing production on a continuous basis as new sensor data is acquired in real time. Permanently acquired data is modeled and analyzed in order to create predictive models. A model based control strategy is used to regulate well and field instrumentation. The optimum field operating point, which changes with time, satisfies the maximum economic return. This work is a starting point for further development in automatic, intelligent reservoir technologies which get the most out of the abilities of permanent, instrumented wells and remotely activated downhole completions. The strategy, tested with history-matched data from a compartmentalised giant field, proved to reduce operating costs while increasing oil recovery by 27% in this field. (author)

  3. Time-Space Topology Optimization

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard

    2008-01-01

    A method for space-time topology optimization is outlined. The space-time optimization strategy produces structures with optimized material distributions that vary in space and in time. The method is demonstrated for one-dimensional wave propagation in an elastic bar that has a time-dependent You......’s modulus and is subjected to a transient load. In the example an optimized dynamic structure is demonstrated that compresses a propagating Gauss pulse....

  4. Checklists for external validity

    DEFF Research Database (Denmark)

    Dyrvig, Anne-Kirstine; Kidholm, Kristian; Gerke, Oke;

    2014-01-01

    RATIONALE, AIMS AND OBJECTIVES: The quality of the current literature on external validity varies considerably. An improved checklist with validated items on external validity would aid decision-makers in judging similarities among circumstances when transferring evidence from a study setting...... to an implementation setting. In this paper, currently available checklists on external validity are identified, assessed and used as a basis for proposing a new improved instrument. METHOD: A systematic literature review was carried out in Pubmed, Embase and Cinahl on English-language papers without time restrictions....... The retrieved checklist items were assessed for (i) the methodology used in primary literature, justifying inclusion of each item; and (ii) the number of times each item appeared in checklists. RESULTS: Fifteen papers were identified, presenting a total of 21 checklists for external validity, yielding a total...

  5. Is it time to use checklists in mental health care auditing?

    Directory of Open Access Journals (Sweden)

    Jacob Polackiewicz

    2011-02-01

    Full Text Available A key strategy for improving the quality of mental health care is the design and implementation of a mechanism for on-site inspection and clinical auditing. We discuss the use of checklists in auditing providing an objective, comprehensive system for recording and analyzing multi-disciplinary, clinical auditing in mental health services. We believe such an approach can identify potential risks and allow for better decision making.

  6. Is it time to use checklists in mental health care auditing?

    Science.gov (United States)

    Abramowitz, Moshe Z.; Polackiewicz, Jacob; Grinshpoon, Alexander

    2011-01-01

    A key strategy for improving the quality of mental health care is the design and implementation of a mechanism for on-site inspection and clinical auditing. We discuss the use of checklists in auditing providing an objective, comprehensive system for recording and analyzing multi-disciplinary, clinical auditing in mental health services. We believe such an approach can identify potential risks and allow for better decision making. PMID:25478101

  7. Implementation of a surgical safety checklist: interventions to optimize the process and hints to increase compliance.

    Directory of Open Access Journals (Sweden)

    Gerald Sendlhofer

    Full Text Available A surgical safety checklist (SSC was implemented and routinely evaluated within our hospital. The purpose of this study was to analyze compliance, knowledge of and satisfaction with the SSC to determine further improvements.The implementation of the SSC was observed in a pilot unit. After roll-out into each operating theater, compliance with the SSC was routinely measured. To assess subjective and objective knowledge, as well as satisfaction with the SSC implementation, an online survey (N = 891 was performed.During two test runs in a piloting unit, 305 operations were observed, 175 in test run 1 and 130 in test run 2. The SSC was used in 77.1% of all operations in test run 1 and in 99.2% in test run 2. Within used SSCs, completion rates were 36.3% in test run 1 and 1.6% in test run 2. After roll-out, three unannounced audits took place and showed that the SSC was used in 95.3%, 91.9% and 89.9%. Within used SSCs, completion rates decreased from 81.7% to 60.6% and 53.2%. In 2014, 164 (18.4% operating team members responded to the online survey, 160 of which were included in the analysis. 146 (91.3% consultants and nursing staff reported to use the SSC regularly in daily routine.These data show that the implementation of new tools such as the adapted WHO SSC needs constant supervision and instruction until it becomes self-evident and accepted. Further efforts, consisting mainly of hands-on leadership and training are necessary.

  8. TimeNET Optimization Environment

    Directory of Open Access Journals (Sweden)

    Christoph Bodenstein

    2015-12-01

    Full Text Available In this paper a novel tool for simulation-based optimization and design-space exploration of Stochastic Colored Petri nets (SCPN is introduced. The working title of this tool is TimeNET Optimization Environment (TOE. Targeted users of this tool are people modeling complex systems with SCPNs in TimeNET who want to find parameter sets that are optimal for a certain performance measure (fitness function. It allows users to create and simulate sets of SCPNs and to run different optimization algorithms based on parameter variation. The development of this tool was motivated by the need to automate and speed up tests of heuristic optimization algorithms to be applied for SCPN optimization. A result caching mechanism is used to avoid recalculations.

  9. Time optimal paths for high speed maneuvering

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.; Lenhart, S.M.

    1993-01-01

    Recent theoretical results have completely solved the problem of determining the minimum length path for a vehicle with a minimum turning radius moving from an initial configuration to a final configuration. Time optimal paths for a constant speed vehicle are a subset of the minimum length paths. This paper uses the Pontryagin maximum principle to find time optimal paths for a constant speed vehicle. The time optimal paths consist of sequences of axes of circles and straight lines. The maximum principle introduces concepts (dual variables, bang-bang solutions, singular solutions, and transversality conditions) that provide important insight into the nature of the time optimal paths. We explore the properties of the optimal paths and present some experimental results for a mobile robot following an optimal path.

  10. Optimizing departure times in vehicle routes

    NARCIS (Netherlands)

    Kok, A.L.; Hans, E.W.; Schutten, J.M.J.

    2008-01-01

    Most solution methods for the vehicle routing problem with time windows (VRPTW) develop routes from the earliest feasible departure time. However, in practice, temporal traffic congestions make that such solutions are not optimal with respect to minimizing the total duty time. Furthermore, VRPTW sol

  11. Time Optimal Reachability Analysis Using Swarm Verification

    DEFF Research Database (Denmark)

    Zhang, Zhengkui; Nielsen, Brian; Larsen, Kim Guldstrand

    2016-01-01

    and planning problems, response time optimization etc. We propose swarm verification to accelerate time optimal reachability using the real-time model-checker Uppaal. In swarm verification, a large number of model checker instances execute in parallel on a computer cluster using different, typically randomized...... search strategies. We develop four swarm algorithms and evaluate them with four models in terms scalability, and time- and memory consumption. Three of these cooperate by exchanging costs of intermediate solutions to prune the search using a branch-and-bound approach. Our results show that swarm...

  12. Nursing Home Checklist

    Science.gov (United States)

    Nursing home checklist Name of nursing home: ____________________________________________________ Address: ________________________________________________________________ Phone number: __________________________________________________________ Date of visit: _____________________________________________________________ Basic information Yes No Notes Is the nursing home Medicare certified? Is the nursing ...

  13. Optimal Investment Strategy to Minimize Occupation Time

    CERN Document Server

    Bayraktar, Erhan

    2008-01-01

    We find the optimal investment strategy to minimize the expected time that an individual's wealth stays below zero, the so-called {\\it occupation time}. The individual consumes at a constant rate and invests in a Black-Scholes financial market consisting of one riskless and one risky asset, with the risky asset's price process following a geometric Brownian motion. We also consider an extension of this problem by penalizing the occupation time for the degree to which wealth is negative.

  14. Distributed Algorithms for Time Optimal Reachability Analysis

    DEFF Research Database (Denmark)

    Zhang, Zhengkui; Nielsen, Brian; Larsen, Kim Guldstrand

    2016-01-01

    . We propose distributed computing to accelerate time optimal reachability analysis. We develop five distributed state exploration algorithms, implement them in \\uppaal enabling it to exploit the compute resources of a dedicated model-checking cluster. We experimentally evaluate the implemented...... algorithms with four models in terms of their ability to compute near- or proven-optimal solutions, their scalability, time and memory consumption and communication overhead. Our results show that distributed algorithms work much faster than sequential algorithms and have good speedup in general....

  15. Thompson Sampling: An Optimal Finite Time Analysis

    CERN Document Server

    Kaufmann, Emilie; Munos, Rémi

    2012-01-01

    The question of the optimality of Thompson Sampling for solving the stochastic multi-armed bandit problem had been open since 1933. In this paper we answer it positively for the case of Bernoulli rewards by providing the first finite-time analysis that matches the asymptotic rate given in the Lai and Robbins lower bound for the cumulative regret. The proof is accompanied by a numerical comparison with other optimal policies, experiments that have been lacking in the literature until now for the Bernoulli case.

  16. Optimal lead time for dengue forecast.

    Directory of Open Access Journals (Sweden)

    Yien Ling Hii

    Full Text Available BACKGROUND: A dengue early warning system aims to prevent a dengue outbreak by providing an accurate prediction of a rise in dengue cases and sufficient time to allow timely decisions and preventive measures to be taken by local authorities. This study seeks to identify the optimal lead time for warning of dengue cases in Singapore given the duration required by a local authority to curb an outbreak. METHODOLOGY AND FINDINGS: We developed a Poisson regression model to analyze relative risks of dengue cases as functions of weekly mean temperature and cumulative rainfall with lag times of 1-5 months using spline functions. We examined the duration of vector control and cluster management in dengue clusters > = 10 cases from 2000 to 2010 and used the information as an indicative window of the time required to mitigate an outbreak. Finally, we assessed the gap between forecast and successful control to determine the optimal timing for issuing an early warning in the study area. Our findings show that increasing weekly mean temperature and cumulative rainfall precede risks of increasing dengue cases by 4-20 and 8-20 weeks, respectively. These lag times provided a forecast window of 1-5 months based on the observed weather data. Based on previous vector control operations, the time needed to curb dengue outbreaks ranged from 1-3 months with a median duration of 2 months. Thus, a dengue early warning forecast given 3 months ahead of the onset of a probable epidemic would give local authorities sufficient time to mitigate an outbreak. CONCLUSIONS: Optimal timing of a dengue forecast increases the functional value of an early warning system and enhances cost-effectiveness of vector control operations in response to forecasted risks. We emphasize the importance of considering the forecast-mitigation gaps in respective study areas when developing a dengue forecasting model.

  17. MMSE Optimal Algebraic Space-Time Codes

    CERN Document Server

    Rajan, G Susinder

    2007-01-01

    Design of Space-Time Block Codes (STBCs) for Maximum Likelihood (ML) reception has been predominantly the main focus of researchers. However, the ML decoding complexity of STBCs becomes prohibitive large as the number of transmit and receive antennas increase. Hence it is natural to resort to a suboptimal reception technique like linear Minimum Mean Squared Error (MMSE) receiver. Barbarossa et al and Liu et al have independently derived necessary and sufficient conditions for a full rate linear STBC to be MMSE optimal, i.e achieve least Symbol Error Rate (SER). Motivated by this problem, certain existing high rate STBC constructions from crossed product algebras are identified to be MMSE optimal. Also, it is shown that a certain class of codes from cyclic division algebras which are special cases of crossed product algebras are MMSE optimal. Hence, these STBCs achieve least SER when MMSE reception is employed and are fully diverse when ML reception is employed.

  18. Winter Weather Checklists

    Science.gov (United States)

    ... Health Matters What's New Preparation & Planning Disasters & Severe Weather Earthquakes Extreme Heat Floods Hurricanes Landslides Tornadoes Tsunamis ... Weather Information on Specific Types of Emergencies Winter Weather Checklists Language: English Español (Spanish) Recommend on Facebook ...

  19. Argos: An Optimized Time-Series Photometer

    Indian Academy of Sciences (India)

    Anjum S. Mukadam; R. E. Nather

    2005-06-01

    We designed a prime focus CCD photometer, Argos, optimized for high speed time-series measurements of blue variables (Nather & Mukadam 2004) for the 2.1 m telescope at McDonald Observatory. Lack of any intervening optics between the primary mirror and the CCD makes the instrument highly efficient.We measure an improvement in sensitivity by a factor of nine over the 3-channel PMT photometers used on the same telescope and for the same exposure time. The CCD frame transfer operation triggered by GPS synchronized pulses serves as an electronic shutter for the photometer. This minimizes the dead time between exposures, but more importantly, allows a precise control of the start and duration of the exposure. We expect the uncertainty in our timing to be less than 100 s.

  20. Optimal timing of carbon sequestration policies

    OpenAIRE

    Lafforgue, Gilles; MOREAUX Michel

    2015-01-01

    Carbon capture and storage (CCS) is one of the most promising abatement options to curb CO2 emissions of the energy sector. Usually, in models where the atmospheric carbon stock is constrained to not exceed a given ceiling and under constant average costs, it is never optimal to deploy CCS before the time at which this ceiling is reached. In this paper, we show that, when the CCS technology is submitted to decreasing returns to scale, abatement activities must begin earlier, i.e. before the c...

  1. Checklists in biomedical publications

    Directory of Open Access Journals (Sweden)

    Pardal-Refoyo JL

    2013-12-01

    Full Text Available Introduction and objectives: the authors, reviewers, editors and readers must have specific tools that help them in the process of drafting, review, or reading the articles. Objective: to offer a summary of the major checklists for different types of biomedical research articles. Material and method: review literature and resources of the EQUATOR Network and adaptations in Spanish published by Medicina Clínica and Evidencias en Pediatría journals. Results: are the checklists elaborated by various working groups. (CONSORT and TREND, experimental studies for observational studies (STROBE, accuracy (STARD diagnostic studies, systematic reviews and meta-analyses (PRISMA and for studies to improve the quality (SQUIRE. Conclusions: the use of checklists help to improve the quality of articles and help to authors, reviewers, to the editor and readers in the development and understanding of the content.

  2. A Perspective on Behaviour Checklists.

    Science.gov (United States)

    Colmar, Susan

    1988-01-01

    Discusses the growing use by educational psychologists and teachers of developmental and academic behavior checklists. Identifies the minimum criteria necessary for checklists and criticizes their use as many fail to meet these standards. Describes the limitations, misuse, and narrow focus of behavior checklists. (GEA)

  3. DETERMINATION METHOD OF OPTIMAL SUPPORTING TIME IN HEADING FACE

    Institute of Scientific and Technical Information of China (English)

    杜长龙; 曹红波; 王燕宁; 张艳

    1997-01-01

    This paper has put forward a concept of optimal supporting time through analysing the influence of the supporting time in the heading face on the supporting result of surrounding rock. The method of the optimal supporting time determined by graphical method is discussed, and the calculating formula for determining the optimal supporting time through the analysis method is derived.

  4. Time optimal paths for a constant speed unicycle

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.

    1991-01-01

    This paper uses the Pontryagin maximum principle to find time optimal paths for a constant speed unicycle. The time optimal paths consist of sequences of arcs of circles and straight lines. The maximum principle introduced concepts (dual variables, bang-bang solutions, singular solutions, and transversality conditions) that provide important insight into the nature of the time optimal paths. 10 refs., 6 figs.

  5. Surgical checklists: the human factor.

    LENUS (Irish Health Repository)

    O Connor, Paul

    2013-05-14

    BACKGROUND: Surgical checklists has been shown to improve patient safety and teamwork in the operating theatre. However, despite the known benefits of the use of checklists in surgery, in some cases the practical implementation has been found to be less than universal. A questionnaire methodology was used to quantitatively evaluate the attitudes of theatre staff towards a modified version of the World Health Organisation (WHO) surgical checklist with relation to: beliefs about levels of compliance and support, impact on patient safety and teamwork, and barriers to the use of the checklist. METHODS: Using the theory of planned behaviour as a framework, 14 semi-structured interviews were conducted with theatre personnel regarding their attitudes towards, and levels of compliance with, a checklist. Based upon the interviews, a 27-item questionnaire was developed and distribute to all theatre personnel in an Irish hospital. RESULTS: Responses were obtained from 107 theatre staff (42.6% response rate). Particularly for nurses, the overall attitudes towards the effect of the checklist on safety and teamworking were positive. However, there was a lack of rigour with which the checklist was being applied. Nurses were significantly more sensitive to the barriers to the use of the checklist than anaesthetists or surgeons. Moreover, anaesthetists were not as positively disposed to the surgical checklist as surgeons and nurse. This finding was attributed to the tendency for the checklist to be completed during a period of high workload for the anaesthetists, resulting in a lack of engagement with the process. CONCLUSION: In order to improve the rigour with which the surgical checklist is applied, there is a need for: the involvement of all members of the theatre team in the checklist process, demonstrated support for the checklist from senior personnel, on-going education and training, and barriers to the implementation of the checklist to be addressed.

  6. Human Factors Checklist: Think Human Factors - Focus on the People

    Science.gov (United States)

    Miller, Darcy; Stelges, Katrine; Barth, Timothy; Stambolian, Damon; Henderson, Gena; Dischinger, Charles; Kanki, Barbara; Kramer, Ian

    2016-01-01

    A quick-look Human Factors (HF) Checklist condenses industry and NASA Agency standards consisting of thousands of requirements into 14 main categories. With support from contractor HF and Safety Practitioners, NASA developed a means to share key HF messages with Design, Engineering, Safety, Project Management, and others. It is often difficult to complete timely assessments due to the large volume of HF information. The HF Checklist evolved over time into a simple way to consider the most important concepts. A wide audience can apply the checklist early in design or through planning phases, even before hardware or processes are finalized or implemented. The checklist is a good place to start to supplement formal HF evaluation. The HF Checklist was based on many Space Shuttle processing experiences and lessons learned. It is now being applied to ground processing of new space vehicles and adjusted for new facilities and systems.

  7. Surgical Safety Checklists : an Update

    OpenAIRE

    BERGS, J.; Hellings, Johan; CLEEMPUT, Irina; SIMONS, Pascale; ZUREL, Ozhan; Vertriest, Sonja; Vandijck, Dominique

    2014-01-01

    Surgical safety checklists aim to improve patient safety by prompting the attention of the surgical team towards critical steps during the operation. The checklist's items are aimed to improve compliance with proven interventions, and to facilitate multidisciplinary communication and teamwork. Based on the current literature, corroborated by systematic reviews and meta-analysis, surgical safety checklists have a positive impact on communication and reduce postoperative complications including...

  8. Surgical checklists: the human factor

    OpenAIRE

    O’Connor, Paul; Reddin, Catriona; O’Sullivan, Michael; O’Duffy, Fergal; Keogh, Ivan

    2013-01-01

    Background Surgical checklists has been shown to improve patient safety and teamwork in the operating theatre. However, despite the known benefits of the use of checklists in surgery, in some cases the practical implementation has been found to be less than universal. A questionnaire methodology was used to quantitatively evaluate the attitudes of theatre staff towards a modified version of the World Health Organisation (WHO) surgical checklist with relation to: beliefs about levels of compli...

  9. Computational methods to obtain time optimal jet engine control

    Science.gov (United States)

    Basso, R. J.; Leake, R. J.

    1976-01-01

    Dynamic Programming and the Fletcher-Reeves Conjugate Gradient Method are two existing methods which can be applied to solve a general class of unconstrained fixed time, free right end optimal control problems. New techniques are developed to adapt these methods to solve a time optimal control problem with state variable and control constraints. Specifically, they are applied to compute a time optimal control for a jet engine control problem.

  10. Optimal time-consistent government debt maturity

    OpenAIRE

    Debortoli, Davide; Nunes, Ricardo; Yared, Pierre

    2016-01-01

    This paper develops a model of optimal government debt maturity in which the government cannot issue state-contingent bonds and cannot commit to fiscal policy. If the government can perfectly commit, it fully insulates the economy against government spending shocks by purchasing short-term assets and issuing long-term debt. These positions are quantitatively very large relative to GDP and do not need to be actively managed by the government. Our main result is that these conclu...

  11. Optimization of PERT Network and Compression of Time

    Institute of Scientific and Technical Information of China (English)

    Li Ping; Hu Jianbing; Gu Xinyi

    2005-01-01

    In the traditional methods of program evaluation and review technique (PERT) network optimization and compression of time limit for project, the uncertainty of free time difference and total time difference were not considered as well as its time risk. The anthors of this paper use the theory of dependent-chance programming to establish a new model about compression of time for project and multi-objective network optimization, which can overcome the shortages of traditional methods and realize the optimization of PERT network directly. By calculating an example with genetic algorithms, the following conclusions are drawn: (1) compression of time is restricted by cost ratio and completion probability of project; (2) activities with maximal standard difference of duration and minimal cost will be compressed in order of precedence; (3) there is no optimal solutions but noninferior solutions between chance and cost, and the most optimal node time depends on decision-maker's preference.

  12. WHO Surgical Checklist and Its Practical Application in Plastic Surgery

    Directory of Open Access Journals (Sweden)

    Shady Abdel-Rehim

    2011-01-01

    Full Text Available The WHO surgical checklist was introduced to most UK surgical units following the WHO “Safe Surgery Saves Lives” initiative. The aim of this audit was to review patient's safety in the delivery of surgical care and to evaluate the practical application of the new WHO surgical checklist. We conducted a retrospective audit of patients who received operative treatment under general anaesthesia at our Plastic Surgery Department, involving a total number of 90 patients. The WHO form was compared to its former equivalents. Complications or incidents occurring during or after surgery were recorded. Using the department's previous surgical checklist, “Time out” was only performed in only 30% of cases. One patient arrived at theatre reception without a completed consent form, and two clinical incidents were reported without patients suffering harm. Following introduction of current WHO surgical checklist, “Time out” was recorded in 80% of cases. In all cases, the new WHO surgical checklist was used and no incidents were reported. The WHO surgical checklist provides a structured frame work that standardizes the delivery of care across hospitals and specialized units; however, it will take some time and practice for teams to learn to use the checklist effectively and reliably.

  13. Optimal Control with Time Delays via the Penalty Method

    Directory of Open Access Journals (Sweden)

    Mohammed Benharrat

    2014-01-01

    Full Text Available We prove necessary optimality conditions of Euler-Lagrange type for a problem of the calculus of variations with time delays, where the delay in the unknown function is different from the delay in its derivative. Then, a more general optimal control problem with time delays is considered. Main result gives a convergence theorem, allowing us to obtain a solution to the delayed optimal control problem by considering a sequence of delayed problems of the calculus of variations.

  14. Handover Outage Time Optimization in Heterogeneous Networks

    Directory of Open Access Journals (Sweden)

    S. Louvros

    2007-01-01

    Full Text Available Handover is a very critical parameter in Cellular Networks. The outage handover time is a drawback for Quality of Service in wireless voice applications and heterogeneous cellular wireless networks. Apart from existing handover technique, a novel approach has been developed known as Network Assisted Handover improving the outage handover time and the fluctuations of data throughput.

  15. Time-limited optimal dynamics beyond the Quantum Speed Limit

    DEFF Research Database (Denmark)

    Gajdacz, Miroslav; Das, Kunal K.; Arlt, Jan;

    2015-01-01

    time-varying control. The problem is addressed in the framework of Hilbert space geometry offering an intuitive interpretation of optimal control algorithms. This approach leads to a necessary criterion for control optimality applicable as a measure of algorithm convergence. The time fidelity trade...

  16. Optimal distribution of measurement time in single channel measurements

    CERN Document Server

    Kaspar, J

    2008-01-01

    Single channel measurements play a minor role in today physics, but they are sometimes unavoidable. Comparing to multichannel measurements, there is distribution of measurement time to be chosen in an experiment design. A method to optimize distribution of measurement time is given, where optimal distribution minimizes standard deviation of a selected fit parameter. As an example, the method is applied to electron spectroscopy experiments.

  17. Constructing the Optimal Solutions to the Undiscounted Continuous-Time Infinite Horizon Optimization Problems

    CERN Document Server

    CAI, Dapeng

    2008-01-01

    We aim to construct the optimal solutions to the undiscounted continuous-time infinite horizon optimization problems, the objective functionals of which may be unbounded. We identify the condition under which the limit of the solutions to the finite horizon problems is optimal for the infinite horizon problems under the overtaking criterion.

  18. Optimal Robust Fault Detection for Linear Discrete Time Systems

    Directory of Open Access Journals (Sweden)

    Nike Liu

    2008-01-01

    Full Text Available This paper considers robust fault-detection problems for linear discrete time systems. It is shown that the optimal robust detection filters for several well-recognized robust fault-detection problems, such as ℋ−/ℋ∞, ℋ2/ℋ∞, and ℋ∞/ℋ∞ problems, are the same and can be obtained by solving a standard algebraic Riccati equation. Optimal filters are also derived for many other optimization criteria and it is shown that some well-studied and seeming-sensible optimization criteria for fault-detection filter design could lead to (optimal but useless fault-detection filters.

  19. Checklists in Neurosurgery to Decrease Preventable Medical Errors: A Review.

    Science.gov (United States)

    Enchev, Yavor

    2015-10-01

    Neurosurgery represents a zero tolerance environment for medical errors, especially preventable ones like all types of wrong site surgery, complications due to the incorrect positioning of patients for neurosurgical interventions and complications due to failure of the devices required for the specific procedure. Following the excellent and encouraging results of the safety checklists in intensive care medicine and in other surgical areas, the checklist was naturally introduced in neurosurgery. To date, the reported world experience with neurosurgical checklists is limited to 15 series with fewer than 20,000 cases in various neurosurgical areas. The purpose of this review was to study the reported neurosurgical checklists according to the following parameters: year of publication; country of origin; area of neurosurgery; type of neurosurgical procedure-elective or emergency; person in charge of the checklist completion; participants involved in completion; whether they prevented incorrect site surgery; whether they prevented complications due to incorrect positioning of the patients for neurosurgical interventions; whether they prevented complications due to failure of the devices required for the specific procedure; their specific aims; educational preparation and training; the time needed for checklist completion; study duration and phases; number of cases included; barriers to implementation; efforts to implementation; team appreciation; and safety outcomes. Based on this analysis, it could be concluded that neurosurgical checklists represent an efficient, reliable, cost-effective and time-saving tool for increasing patient safety and elevating the neurosurgeons' self-confidence. Every neurosurgical department must develop its own neurosurgical checklist or adopt and modify an existing one according to its specific features and needs in an attempt to establish or develop its safety culture. The world, continental, regional and national neurosurgical societies

  20. Engineering applications of discrete-time optimal control

    DEFF Research Database (Denmark)

    Vidal, Rene Victor Valqui; Ravn, Hans V.

    1990-01-01

    of some well-known and new results in discrete time optimal control methods applicable to practical problem solving within engineering. Emphasis is placed on dynamic programming, the classical maximum principle and generalized versions of the maximum principle for optimal control of discrete time......Many problems of design and operation of engineering systems can be formulated as optimal control problems where time has been discretisized. This is also true even if 'time' is not involved in the formulation of the problem, but rather another one-dimensional parameter. This paper gives a review...

  1. Time optimal route planning algorithm of LBS online navigation

    Science.gov (United States)

    Li, Yong; Bao, Shitai; Su, Kui; Fang, Qiushui; Yang, Jingfeng

    2011-02-01

    This paper proposes a time optimal route planning optimization algorithm in the mode of LBS online navigation based on the improved Dijkstra algorithms. Combined with the returning real-time location information by on-line users' handheld terminals, the algorithm can satisfy requirement of the optimal time in the mode of LBS online navigation. A navigation system is developed and applied in actual navigation operations. Operating results show that the algorithm could form a reasonable coordination on the basis of shortest route and fastest velocity in the requirement of optimal time. The algorithm could also store the calculated real-time route information in the cache to improve the efficiency of route planning and to reduce the planning time-consuming.

  2. Model Parameterization Tailored to Real-Time Optimization

    OpenAIRE

    Chachuat, B.; Srinivasan, B.; Bonvin, D.

    2008-01-01

    Challenges in real-time process optimization mainly arise from the inability to build and adapt accurate models for complex physico-chemical processes. This paper surveys different ways of using measurements to compensate for model uncertainty in the context of process optimization. Three approaches can be distinguished according to the quantities that are adapted: model- parameter adaptation updates the parameters of the process model and repeats the optimization, modi...

  3. Optimal Time of Tracheotomy in Infants

    Directory of Open Access Journals (Sweden)

    Sevim Unal MD

    2015-01-01

    Full Text Available Objective. Infants with respiratory failure may require prolonged intubation. There is no consensus on the time of tracheotomy in neonates. Methods. We evaluated infants applied tracheotomy, time of procedure, and early complications in our neonatal intensive care unit (NICU retrospectively from January 2012 to December 2013. Results. We identified 9 infants applied tracheotomy with gestational ages 34 to 41 weeks. Their diagnoses were hypotonic infant, subglottic stenosis, laryngeal cleft, neck mass, and chronic lung disease. Age on tracheotomy ranged from 4 to 10 weeks. Early complication ratio was 33.3% with minimal bleeding (1, air leak (1, and canal revision requirement (1. We discharged 7 infants, and 2 infants died in the NICU. Conclusion. Tracheotomy makes infant nursing easy for staff and families even at home. If carried out by a trained team, the procedure is safe and has low complication. When to apply tracheotomy should be individualized, and airway damage due to prolonged intubation versus risks of tracheotomy should be taken into consideration.

  4. Multicriteria Optimization of Antennas in Time-Domain

    Directory of Open Access Journals (Sweden)

    J. Lacik

    2010-04-01

    Full Text Available An original approach to the time-domain multicriteria optimization of antennas is presented. For a given excitation pulse, the time-domain objective function takes the “time-domain impedance matching”, distortion of responses at the feeding point and in a desired radiating direction (with respect to the excitation pulse, and the radiated energy in the desired direction into account. The objective function is tested on the optimization of a bow-tie antenna using the particle swarm optimization. The proposed approach is suitable for the design of broadband antennas.

  5. A buffer insertion and simultaneous sizing timing optimization algorithm

    Institute of Scientific and Technical Information of China (English)

    Yin Guoli; Lin Zhenghui

    2006-01-01

    A path-based timing optimization algorithm for buffer insertion and simultaneous sizing is proposed.Firstly, candidate buffer insertion location and buffer size for each branch in a given routing path were obtained via localized timing optimization. Then, through evaluating each potential insertion against design objectives, potential optimal buffer insertion locations and sizes for the whole routing tree were determined. At last, by removing redundant buffer insertion operations which do not maximize S ( so ), given timing requirements are finally fulfilled through minimum number of buffers.

  6. Travel time impacts analysis of system-wide signal timing optimization methodology

    OpenAIRE

    Ainchil Cayuela, Luis María

    2014-01-01

    This study analyzes the economic impact that users would experience with the travel time variation due to system-wide signal timing optimization. To do this, a comprehensive analysis of travel time user benefits is conducted using traffic volume, speed and other attributes of road network, before and after signal timing optimization.

  7. Optimal Guaranteed Service Time and Service Level Decision with Time and Service Level Sensitive Demand

    Directory of Open Access Journals (Sweden)

    Sangjun Park

    2014-01-01

    Full Text Available We consider a two-stage supply chain with one supplier and one retailer. The retailer sells a product to customer and the supplier provides a product in a make-to-order mode. In this case, the supplier’s decisions on service time and service level and the retailer’s decision on retail price have effects on customer demand. We develop optimization models to determine the optimal retail price, the optimal guaranteed service time, the optimal service level, and the optimal capacity to maximize the expected profit of the whole supply chain. The results of numerical experiments show that it is more profitable to determine the optimal price, the optimal guaranteed service time, and the optimal service level simultaneously and the proposed model is more profitable in service level sensitive market.

  8. Time/Computationally Optimal Network Architecture: Wireless Sensor Fusion

    OpenAIRE

    Devi, Gadi Gayathri; Kumari, Priya; Jyoshna, Eslavath; Deepika; Murthy, Garimella Rama

    2013-01-01

    In this research paper, the problems dealing with sensor network architecture, sensor fusion are addressed. Time/Computationally optimal network architectures are investigated. Some novel ideas on sensor fusion are proposed.

  9. Timing optimization utilizing order statistics and multichannel digital silicon photomultipliers

    NARCIS (Netherlands)

    Mandai, S.; Venialgo, E.; Charbon, E.

    2014-01-01

    We present an optimization technique utilizing order statistics with a multichannel digital silicon photomultiplier (MD-SiPM) for timing measurements. Accurate timing measurements are required by 3D rangefinding and time-of-flight positron emission tomography, to name a few applications. We have dem

  10. Sufficient Conditions for Feasibility and Optimality of Real-Time Optimization Schemes - I. Theoretical Foundations

    OpenAIRE

    Bunin, Gene; François, Grégory; Bonvin, Dominique

    2013-01-01

    The idea of iterative process optimization based on collected output measurements, or "real-time optimization" (RTO), has gained much prominence in recent decades, with many RTO algorithms being proposed, researched, and developed. While the essential goal of these schemes is to drive the process to its true optimal conditions without violating any safety-critical, or "hard", constraints, no generalized, unified approach for guaranteeing this behavior exists. In this two-part paper, we propos...

  11. Sufficient Conditions for Feasibility and Optimality of Real-Time Optimization Schemes - II. Implementation Issues

    OpenAIRE

    Bunin, Gene; François, Grégory; Bonvin, Dominique

    2013-01-01

    The idea of iterative process optimization based on collected output measurements, or "real-time optimization" (RTO), has gained much prominence in recent decades, with many RTO algorithms being proposed, researched, and developed. While the essential goal of these schemes is to drive the process to its true optimal conditions without violating any safety-critical, or "hard", constraints, no generalized, unified approach for guaranteeing this behavior exists. In this two-part paper, we propos...

  12. Solar sail time-optimal interplanetary transfer trajectory design

    Institute of Scientific and Technical Information of China (English)

    Sheng-Ping Gong; Yun-Feng Gao; Jun-Feng Li

    2011-01-01

    The fuel consumption associated with some interplanetary transfer trajectories using chemical propulsion is not affordable.A solar sail is a method of propulsion that does not consume fuel.Transfer time is one of the most pressing problems of solar sail transfer trajectory design.This paper investigates the time-optimal interplanetary transfer trajectories to a circular orbit of given inclination and radius.The optimal control law is derived from the principle of maximization.An indirect method is used to solve the optimal control problem by selecting values for the initial adjoint variables,which are normalized within a unit sphere.The conditions for the existence of the time-optimal transfer are dependent on the lightness number of the sail and the inclination and radius of the target orbit.A numerical method is used to obtain the boundary values for the time-optimal transfer trajectories.For the cases where no time-optimal transfer trajectories exist,first-order necessary conditions of the optimal control are proposed to obtain feasible solutions.The results show that the transfer time decreases as the minimum distance from the Sun decreases during the transfer duration.For a solar sail with a small lightness number,the transfer time may be evaluated analytically for a three-phase transfer trajectory.The analytical results are compared with previous results and the associated numerical results.The transfer time of the numerical result here is smaller than the transfer time from previous results and is larger than the analytical result.

  13. Time-optimal feedback control for linear systems

    International Nuclear Information System (INIS)

    The paper deals with the results of qualitative investigations of the time-optimal feedback control for linear systems with constant coefficients. In the first section, after some definitions and notations, two examples are given and it is shown that even the time-optimal control problem for linear systems with constant coefficients which looked like ''completely solved'' requires a further qualitative investigation of the stability to ''permanent perturbations'' of optimal feedback control. In the second section some basic results of the linear time-optimal control problem are reviewed. The third section deals with the definition of Boltyanskii's ''regular synthesis'' and its connection to Filippov's theory of right-hand side discontinuous differential equations. In the fourth section a theorem is proved concerning the stability to perturbations of time-optimal feedback control for linear systems with scalar control. In the last two sections it is proved that, if the matrix which defines the system has only real eigenvalues or is three-dimensional, the time-optimal feedback control defines a regular synthesis and therefore is stable to perturbations. (author)

  14. Optimal Selection of Parameters for Nonuniform Embedding of Chaotic Time Series Using Ant Colony Optimization.

    Science.gov (United States)

    Shen, Meie; Chen, Wei-Neng; Zhang, Jun; Chung, Henry Shu-Hung; Kaynak, Okyay

    2013-04-01

    The optimal selection of parameters for time-delay embedding is crucial to the analysis and the forecasting of chaotic time series. Although various parameter selection techniques have been developed for conventional uniform embedding methods, the study of parameter selection for nonuniform embedding is progressed at a slow pace. In nonuniform embedding, which enables different dimensions to have different time delays, the selection of time delays for different dimensions presents a difficult optimization problem with combinatorial explosion. To solve this problem efficiently, this paper proposes an ant colony optimization (ACO) approach. Taking advantage of the characteristic of incremental solution construction of the ACO, the proposed ACO for nonuniform embedding (ACO-NE) divides the solution construction procedure into two phases, i.e., selection of embedding dimension and selection of time delays. In this way, both the embedding dimension and the time delays can be optimized, along with the search process of the algorithm. To accelerate search speed, we extract useful information from the original time series to define heuristics to guide the search direction of ants. Three geometry- or model-based criteria are used to test the performance of the algorithm. The optimal embeddings found by the algorithm are also applied in time-series forecasting. Experimental results show that the ACO-NE is able to yield good embedding solutions from both the viewpoints of optimization performance and prediction accuracy. PMID:23144038

  15. Discrete-time inverse optimal control for nonlinear systems

    CERN Document Server

    Sanchez, Edgar N

    2013-01-01

    Discrete-Time Inverse Optimal Control for Nonlinear Systems proposes a novel inverse optimal control scheme for stabilization and trajectory tracking of discrete-time nonlinear systems. This avoids the need to solve the associated Hamilton-Jacobi-Bellman equation and minimizes a cost functional, resulting in a more efficient controller. Design More Efficient Controllers for Stabilization and Trajectory Tracking of Discrete-Time Nonlinear Systems The book presents two approaches for controller synthesis: the first based on passivity theory and the second on a control Lyapunov function (CLF). Th

  16. Time dependent optimal switching controls in online selling models

    Energy Technology Data Exchange (ETDEWEB)

    Bradonjic, Milan [Los Alamos National Laboratory; Cohen, Albert [MICHIGAN STATE UNIV

    2010-01-01

    We present a method to incorporate dishonesty in online selling via a stochastic optimal control problem. In our framework, the seller wishes to maximize her average wealth level W at a fixed time T of her choosing. The corresponding Hamilton-Jacobi-Bellmann (HJB) equation is analyzed for a basic case. For more general models, the admissible control set is restricted to a jump process that switches between extreme values. We propose a new approach, where the optimal control problem is reduced to a multivariable optimization problem.

  17. Optimization of recurrent neural networks for time series modeling

    DEFF Research Database (Denmark)

    Pedersen, Morten With

    1997-01-01

    The present thesis is about optimization of recurrent neural networks applied to time series modeling. In particular is considered fully recurrent networks working from only a single external input, one layer of nonlinear hidden units and a li near output unit applied to prediction of discrete time...

  18. Time Optimized Algorithm for Web Document Presentation Adaptation

    DEFF Research Database (Denmark)

    Pan, Rong; Dolog, Peter

    2010-01-01

    Currently information on the web is accessed through different devices. Each device has its own properties such as resolution, size, and capabilities to display information in different format and so on. This calls for adaptation of information presentation for such platforms. This paper proposes...... content-optimized and time-optimized algorithms for information presentation adaptation for different devices based on its hierarchical model. The model is formalized in order to experiment with different algorithms....

  19. Time-optimal control of infinite order distributed parabolic systems involving time lags

    Directory of Open Access Journals (Sweden)

    G.M. Bahaa

    2014-06-01

    Full Text Available A time-optimal control problem for linear infinite order distributed parabolic systems involving constant time lags appear both in the state equation and in the boundary condition is presented. Some particular properties of the optimal control are discussed.

  20. Optimal Time-Trial Bicycle Racing with Headwinds and Tailwinds

    CERN Document Server

    Anton, A Brad

    2013-01-01

    Many time-trial and triathlon bicycle races take place on relatively flat, closed-circuit courses. In the absence of hills, riding-speed is limited almost solely by aerodynamic drag; consequently, winds can have a big effect on elapsed times. I analyze the special case of a straight out-and-back race in a steady wind, assuming the rider has a given total amount of energy to expend and can choose only two speeds - the aided speed with tailwind and the hindered speed into headwind. In this ideal circumstance the problem of choosing optimal riding speeds reduces to a constrained nonlinear optimization that can be solved with elementary calculus. My analysis reveals a practical rule of thumb that can be used more generally to choose optimal riding speeds for time-trial racing on closed-circuit courses in the presence of headwinds and tailwinds.

  1. Analysis and Optimization of Distributed Real-Time Embedded Systems

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo;

    2006-01-01

    An increasing number of real-time applications are today implemented using distributed heterogeneous architectures composed of interconnected networks of processors. The systems are heterogeneous not only in terms of hardware and software components, but also in terms of communication protocols...... and scheduling policies. In this context, the task of designing such systems is becoming increasingly difficult. The success of new adequate design methods depends on the availability of efficient analysis as well as optimization techniques. In this paper, we present both analysis and optimization approaches...... for such heterogeneous distributed real-time embedded systems. More specifically, we discuss the schedulability analysis of hard real-time systems, highlighting particular aspects related to the heterogeneous and distributed nature of the applications. We also introduce several design optimization problems...

  2. An Optimizing Framework for Real-time Scheduling

    OpenAIRE

    Sundharam, Sakthivel Manikandan; Altmeyer, Sebastian; Navet, Nicolas

    2016-01-01

    Scheduling is crucial in real-time applications. For any real-time system, the desired scheduling policy can be selected based on the scheduling problem itself and the underlying system constraints. This paper discusses a novel optimization framework which automates the selection and configuration of the scheduling policy. The objective is to let designer state the permissible timing behavior of the system in a declarative manner. The system synthesis step involving both ...

  3. Near-time-optimal control for quantum systems

    Science.gov (United States)

    Chen, Qi-Ming; Wu, Re-Bing; Zhang, Tian-Ming; Rabitz, Herschel

    2015-12-01

    For a quantum system controlled by an external field, time-optimal control is referred to as the shortest-time-duration control that can still permit maximizing an objective function J , which is especially a desirable goal for engineering quantum dynamics against decoherence effects. However, since rigorously finding a time-optimal control is usually very difficult and in many circumstances the control is only required to be sufficiently short and precise, one can design algorithms seeking such suboptimal control solutions for much reduced computational effort. In this paper, we propose an iterative algorithm for finding near-time-optimal control in a high level set (i.e., the set of controls that achieves the same value of J ) that can be arbitrarily close to the global optima. The algorithm proceeds seeking to decrease the time duration T while the value of J remains invariant, until J leaves the level-set value; the deviation of J due to numerical errors is corrected by gradient climbing that brings the search back to the level-set J value. Since the level set is very close to the maximum value of J , the resulting control solution is nearly time optimal with manageable precision. Numerical examples demonstrate the effectiveness and general applicability of the algorithm.

  4. Optimal Conditional Reachability for Multi-Priced Timed Automata

    DEFF Research Database (Denmark)

    Larsen, Kim Guldstrand; Rasmussen, Jacob Illum

    2005-01-01

    In this paper, we prove decidability of the optimal conditional reachability problem for multi-priced timed automata, an extension of timed automata with multiple cost variables evolving according to given rates for each location. More precisely, we consider the problem of determining the minimal...... cost of reaching a given target state, with respect to some primary cost variable, while respecting upper bound constraints on the remaining (secondary) cost variables. Decidability is proven by constructing a zone-based algorithm that always terminates while synthesizing the optimal cost with a single...

  5. Analysis and Optimization of Heterogeneous Real-Time Embedded Systems

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo

    2005-01-01

    . The success of such new design methods depends on the availability of analysis and optimization techniques. In this paper, we present analysis and optimization techniques for heterogeneous real-time embedded systems. We address in more detail a particular class of such systems called multi-clusters, composed......An increasing number of real-time applications are today implemented using distributed heterogeneous architectures composed of interconnected networks of processors. The systems are heterogeneous not only in terms of hardware components, but also in terms of communication protocols and scheduling...

  6. Optimal estimation of recurrence structures from time series

    Science.gov (United States)

    beim Graben, Peter; Sellers, Kristin K.; Fröhlich, Flavio; Hutt, Axel

    2016-05-01

    Recurrent temporal dynamics is a phenomenon observed frequently in high-dimensional complex systems and its detection is a challenging task. Recurrence quantification analysis utilizing recurrence plots may extract such dynamics, however it still encounters an unsolved pertinent problem: the optimal selection of distance thresholds for estimating the recurrence structure of dynamical systems. The present work proposes a stochastic Markov model for the recurrent dynamics that allows for the analytical derivation of a criterion for the optimal distance threshold. The goodness of fit is assessed by a utility function which assumes a local maximum for that threshold reflecting the optimal estimate of the system's recurrence structure. We validate our approach by means of the nonlinear Lorenz system and its linearized stochastic surrogates. The final application to neurophysiological time series obtained from anesthetized animals illustrates the method and reveals novel dynamic features of the underlying system. We propose the number of optimal recurrence domains as a statistic for classifying an animals' state of consciousness.

  7. Particle swarm optimization for discrete-time inverse optimal control of a doubly fed induction generator.

    Science.gov (United States)

    Ruiz-Cruz, Riemann; Sanchez, Edgar N; Ornelas-Tellez, Fernando; Loukianov, Alexander G; Harley, Ronald G

    2013-12-01

    In this paper, the authors propose a particle swarm optimization (PSO) for a discrete-time inverse optimal control scheme of a doubly fed induction generator (DFIG). For the inverse optimal scheme, a control Lyapunov function (CLF) is proposed to obtain an inverse optimal control law in order to achieve trajectory tracking. A posteriori, it is established that this control law minimizes a meaningful cost function. The CLFs depend on matrix selection in order to achieve the control objectives; this matrix is determined by two mechanisms: initially, fixed parameters are proposed for this matrix by a trial-and-error method and then by using the PSO algorithm. The inverse optimal control scheme is illustrated via simulations for the DFIG, including the comparison between both mechanisms. PMID:24273145

  8. Quickest Time Herding and Detection for Optimal Social Learning

    CERN Document Server

    Krishnamurthy, Vikram

    2010-01-01

    This paper considers social learning amongst rational agents (for example, sensors in a network). We consider three models of social learning in increasing order of sophistication. In the first model, based on its private observation of a noisy underlying state process, each agent selfishly optimizes its local utility and broadcasts its action. This protocol leads to a herding behavior where the agents eventually choose the same action irrespective of their observations. We then formulate a second more general model where each agent is benevolent and chooses its sensor-mode to optimize a social welfare function to facilitate social learning. Using lattice programming and stochastic orders, it is shown that the optimal decision each agent makes is characterized by a switching curve on the space of Bayesian distributions. We then present a third more general model where social learning takes place to achieve quickest time change detection. Both geometric and phase-type change time distributions are considered. ...

  9. Hard and Soft Sub-Time-Optimal Robust Controllers

    DEFF Research Database (Denmark)

    Kulczycki, Piotr; Wisniewski, Rafal; Kowalski, Piotr;

    2010-01-01

    has been treated as a stochastic process, is presented in this paper. As a result, through a generalization of the classic switching curve occurring in the time-optimal approach, two control structures have been investigated: the hard, defined on the basis of the rules of the statistical decision...

  10. An optimal real-time controller for vertical plasma stabilization

    CERN Document Server

    Cruz, N; Coda, S; Duval, B P; Le, H B; Rodrigues, A P; Varandas, C A F; Correia, C M B A; Goncalves, B S

    2014-01-01

    Modern Tokamaks have evolved from the initial axisymmetric circular plasma shape to an elongated axisymmetric plasma shape that improves the energy confinement time and the triple product, which is a generally used figure of merit for the conditions needed for fusion reactor performance. However, the elongated plasma cross section introduces a vertical instability that demands a real-time feedback control loop to stabilize the plasma vertical position and velocity. At the Tokamak \\`a Configuration Variable (TCV) in-vessel poloidal field coils driven by fast switching power supplies are used to stabilize highly elongated plasmas. TCV plasma experiments have used a PID algorithm based controller to correct the plasma vertical position. In late 2013 experiments a new optimal real-time controller was tested improving the stability of the plasma. This contribution describes the new optimal real-time controller developed. The choice of the model that describes the plasma response to the actuators is discussed. The ...

  11. Finite time exergoeconomic performance optimization of a thermoacoustic heat engine

    Directory of Open Access Journals (Sweden)

    Xuxian Kan, Lingen Chen, Fengrui Sun, Feng Wu

    2011-01-01

    Full Text Available Finite time exergoeconomic performance optimization of a generalized irreversible thermoacoustic heat engine with heat resistance, heat leakage, thermal relaxation, and internal dissipation is investigated in this paper. Both the real part and the imaginary part of the complex heat transfer exponent change the optimal profit rate versus efficiency relationship quantitatively. The operation of the generalized irreversible thermoacoustic engine is viewed as a production process with exergy as its output. The finite time exergoeconomic performance optimization of the generalized irreversible thermoacoustic engine is performed by taking profit rate as the objective. The analytical formulas about the profit rate and thermal efficiency of the thermoacoustic engine are derived. Furthermore, the comparative analysis of the influences of various factors on the relationship between optimal profit rate and the thermal efficiency of the generalized irreversible thermoacoustic engine is carried out by detailed numerical examples. The optimal zone on the performance of the thermoacoustic heat engine is obtained by numerical analysis. The results obtained herein may be useful for the selection of the operation parameters for real thermoacoustic heat engines.

  12. Optimizing the search for transiting planets in long time series

    Science.gov (United States)

    Ofir, Aviv

    2014-01-01

    Context. Transit surveys, both ground- and space-based, have already accumulated a large number of light curves that span several years. Aims: The search for transiting planets in these long time series is computationally intensive. We wish to optimize the search for both detection and computational efficiencies. Methods: We assume that the searched systems can be described well by Keplerian orbits. We then propagate the effects of different system parameters to the detection parameters. Results: We show that the frequency information content of the light curve is primarily determined by the duty cycle of the transit signal, and thus the optimal frequency sampling is found to be cubic and not linear. Further optimization is achieved by considering duty-cycle dependent binning of the phased light curve. By using the (standard) BLS, one is either fairly insensitive to long-period planets or less sensitive to short-period planets and computationally slower by a significant factor of ~330 (for a 3 yr long dataset). We also show how the physical system parameters, such as the host star's size and mass, directly affect transit detection. This understanding can then be used to optimize the search for every star individually. Conclusions: By considering Keplerian dynamics explicitly rather than implicitly one can optimally search the BLS parameter space. The presented Optimal BLS enhances the detectability of both very short and very long period planets, while allowing such searches to be done with much reduced resources and time. The Matlab/Octave source code for Optimal BLS is made available. The MATLAB code is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/561/A138

  13. A Checklist for Safe Schools.

    Science.gov (United States)

    Schiffbauer, Pam

    2000-01-01

    School buildings ideally would have few exterior access points, no isolated hallways, and sunlit classrooms. A safety checklist recommends locating offices near main doors, monitoring hallway traffic, enhancing communications, updating crisis-management plans, teaching coping skills, standardizing dismissal policies, and ensuring legal compliance…

  14. Resource-Optimal Scheduling Using Priced Timed Automata

    DEFF Research Database (Denmark)

    Larsen, Kim Guldstrand; Rasmussen, Jacob Illum; Subramani, K.

    2004-01-01

    In this paper, we show how the simple structure of the linear programs encountered during symbolic minimum-cost reachability analysis of priced timed automata can be exploited in order to substantially improve the performance of the current algorithm. The idea is rooted in duality of linear progr......-80 percent performance gain. As a main application area, we show how to solve energy-optimal task graph scheduling problems using the framework of priced timed automata....

  15. Part-Time Unemployment and Optimal Unemployment Insurance

    OpenAIRE

    Ek, Susanne; Holmlund, Bertil

    2011-01-01

    A significant fraction of the labor force consists of employed workers who are part-time unemployed (underemployed) in the sense that they are unable to work as much as they prefer. This paper develops a search and matching model to study the design of optimal unemployment insurance in an economy with unemployment as well as part-time unemployment. Part-time unemployment provides income insurance and serves as a stepping stone to full-time jobs. Unemployment benefits for part-timers increase ...

  16. Comparison of time optimal control for two level quantum systems

    Institute of Scientific and Technical Information of China (English)

    Shuang Cong; Jie Wen; Xubo Zou

    2014-01-01

    The time optimal problem for a two level quantum sys-tem is studied. We compare two different control strategies of bang-bang control and the geometric control, respectively, es-pecial y in the case of minimizing the time of steering the state from North Pole to South Pole on the Bloch sphere with bounded control. The time performances are compared for different param-eters by the individual numerical simulation experiments, and the experimental results are analyzed. The results show that the ge-ometric control spends less time than the bang-bang control does.

  17. Optimal moving grids for time-dependent partial differential equations

    Science.gov (United States)

    Wathen, A. J.

    1992-01-01

    Various adaptive moving grid techniques for the numerical solution of time-dependent partial differential equations were proposed. The precise criterion for grid motion varies, but most techniques will attempt to give grids on which the solution of the partial differential equation can be well represented. Moving grids are investigated on which the solutions of the linear heat conduction and viscous Burgers' equation in one space dimension are optimally approximated. Precisely, the results of numerical calculations of optimal moving grids for piecewise linear finite element approximation of PDE solutions in the least-squares norm are reported.

  18. Optimal Time to Invest Energy Storage System under Uncertainty Conditions

    Directory of Open Access Journals (Sweden)

    Yongma Moon

    2014-04-01

    Full Text Available This paper proposes a model to determine the optimal investment time for energy storage systems (ESSs in a price arbitrage trade application under conditions of uncertainty over future profits. The adoption of ESSs can generate profits from price arbitrage trade, which are uncertain because the future marginal prices of electricity will change depending on supply and demand. In addition, since the investment is optional, an investor can delay adopting an ESS until it becomes profitable, and can decide the optimal time. Thus, when we evaluate this investment, we need to incorporate the investor’s option which is not captured by traditional evaluation methods. In order to incorporate these aspects, we applied real option theory to our proposed model, which provides an optimal investment threshold. Our results concerning the optimal time to invest show that if future profits that are expected to be obtained from arbitrage trade become more uncertain, an investor needs to wait longer to invest. Also, improvement in efficiency of ESSs can reduce the uncertainty of arbitrage profit and, consequently, the reduced uncertainty enables earlier ESS investment, even for the same power capacity. Besides, when a higher rate of profits is expected and ESS costs are higher, an investor needs to wait longer. Also, by comparing a widely used net present value model to our real option model, we show that the net present value method underestimates the value for ESS investment and misleads the investor to make an investment earlier.

  19. Optimal redundant systems for works with random processing time

    International Nuclear Information System (INIS)

    This paper studies the optimal redundant policies for a manufacturing system processing jobs with random working times. The redundant units of the parallel systems and standby systems are subject to stochastic failures during the continuous production process. First, a job consisting of only one work is considered for both redundant systems and the expected cost functions are obtained. Next, each redundant system with a random number of units is assumed for a single work. The expected cost functions and the optimal expected numbers of units are derived for redundant systems. Subsequently, the production processes of N tandem works are introduced for parallel and standby systems, and the expected cost functions are also summarized. Finally, the number of works is estimated by a Poisson distribution for the parallel and standby systems. Numerical examples are given to demonstrate the optimization problems of redundant systems

  20. Optimal Real-time Dispatch for Integrated Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, Ryan Michael [Univ. of California, Berkeley, CA (United States)

    2007-05-31

    This report describes the development and application of a dispatch optimization algorithm for integrated energy systems (IES) comprised of on-site cogeneration of heat and electricity, energy storage devices, and demand response opportunities. This work is intended to aid commercial and industrial sites in making use of modern computing power and optimization algorithms to make informed, near-optimal decisions under significant uncertainty and complex objective functions. The optimization algorithm uses a finite set of randomly generated future scenarios to approximate the true, stochastic future; constraints are included that prevent solutions to this approximate problem from deviating from solutions to the actual problem. The algorithm is then expressed as a mixed integer linear program, to which a powerful commercial solver is applied. A case study of United States Postal Service Processing and Distribution Centers (P&DC) in four cities and under three different electricity tariff structures is conducted to (1) determine the added value of optimal control to a cogeneration system over current, heuristic control strategies; (2) determine the value of limited electric load curtailment opportunities, with and without cogeneration; and (3) determine the trade-off between least-cost and least-carbon operations of a cogeneration system. Key results for the P&DC sites studied include (1) in locations where the average electricity and natural gas prices suggest a marginally profitable cogeneration system, optimal control can add up to 67% to the value of the cogeneration system; optimal control adds less value in locations where cogeneration is more clearly profitable; (2) optimal control under real-time pricing is (a) more complicated than under typical time-of-use tariffs and (b) at times necessary to make cogeneration economic at all; (3) limited electric load curtailment opportunities can be more valuable as a compliment to the cogeneration system than alone; and

  1. Trajectory optimization for real-time guidance. I - Time-varying LQR on a parallel processor

    Science.gov (United States)

    Psiaki, Mark L.; Park, Kihong

    1990-01-01

    A key algorithmic element of a real-time trajectory optimization hardware/software implementation, the quadratic program (QP) solver element, is presented. The purpose of the effort is to make nonlinear trajectory optimization fast enough to provide real-time commands during guidance of a vehicle such as an aeromaneuvering orbiter. Many methods of nonlinear programming require the solution of a QP at each iteration. In the trajectory optimization case the QP has a special dynamic programming structure, a LQR-like structure. QP algorithm speed is increased by taking advantage of this special structure and by parallel implementation.

  2. Free Final-Time Optimal Control for HIV Viral Dynamics

    CERN Document Server

    Pachpute, Gaurav

    2011-01-01

    In this paper, we examine a well-established model for HIV wild-type infection. The algorithm for steepest descent method for fixed final-time is stated and a modified method for free final-time is presented. The first type of cost functional considered, seeks to minimize the total time of therapy. An easy implementation for this problem suggests that it can be effective in the early stages of treatment as well as for individual-based studies, due to the "hit first and hit hard" nature of optimal control. An LQR based cost functional is also presented and the solution is found using steepest descent method. It suggests that the optimal therapy must remain high until the patient shows signs of recovery after which, the therapy gradually decreases. This is in line with the biomedical philosophy. Solution to a modified problem which includes a weight for total time is approximated using the modified algorithm. It shows a considerable drop in the total period. We conclude that, a decreased and optimized therapy p...

  3. Parareal in time intermediate targets methods for optimal control problem

    CERN Document Server

    Maday, Yvon; Salomon, Julien

    2012-01-01

    In this paper, we present a method that enables solving in parallel the Euler-Lagrange system associated with the optimal control of a parabolic equation. Our approach is based on an iterative update of a sequence of intermediate targets that gives rise to independent sub-problems that can be solved in parallel. This method can be coupled with the parareal in time algorithm. Numerical experiments show the efficiency of our method.

  4. Higher order variational time discretization of optimal control problems

    CERN Document Server

    Campos, C M; Ober-Blöbaum, S

    2012-01-01

    We reconsider the variational integration of optimal control problems for mechanical systems based on a direct discretization of the Lagrange-d'Alembert principle. This approach yields discrete dynamical constraints which by construction preserve important structural properties of the system, like the evolution of the momentum maps or the energy behavior. Here, we employ higher order quadrature rules based on polynomial collocation. The resulting variational time discretization decreases the overall computational effort.

  5. FAME Storage Time in an Optimized Natural Antioxidant Mixture

    OpenAIRE

    Rodolfo Lopes Coppo; Dionísio Borsato; Jaqueline Laís Pereira; Hágata Cremasco da Silva

    2013-01-01

    The study of B100 biodiesel oxidation stability, and its conservation, is extremely important to control its quality, especially regarding storage. Many spices have shown antioxidant effect and are the targets of study. Knowing the oxidation process in greater detail allows a reliable storage period to be stipulated for the biodiesel without its degradation until the time of use. Results have shown that according to the accelerated stove method, the optimal mixture, composed of 100% of oregan...

  6. Nearly time-optimal paths for a ground vehicle

    Institute of Scientific and Technical Information of China (English)

    David A. ANISI; Johan HAMBERG; Xiaoming HU

    2003-01-01

    It is well known that the sufficient family of time-optimal paths for both Dubins' as well as Reeds-Shepp' s car models consist of the concatenation of circular arcs with maxmum curvature and straight line segments, all tangentially connected.These time-optimal solutions suffer from some drawbacks. Their discontinuous curvature profde, together with the wear and impairment on the control equipment that the bang-bang solutions induce, calls for "smoother" and more supple reference paths to follow. Avoiding the bang-bang solutions also raises the robustness with respect to any possible uncertainties. In this paper, our main tool for generating these "nearly time-optimal", but nevertheless continuous-curvature paths, is to use the Pontryagin Maximum Principle (PMP) and make an appropriate and cunning choice of the Lagrangian function. Despite some rewarding simuhtion results, this concept tums out to be numerically divergent at some instances. Upon a more careful investigation, it can be concluded that the problem at hand is nearly singular. This is seen by applying the PMP to Dubins' car and studying the corresponding two point boundary value problem, which turn out to be singuhr. Realizing this, one is able to contradict the widespread belief that all the information about the motion of a mobile platform lies in the initial values of the auxiliary variables associated with the PMP.

  7. Optimized Paraunitary Filter Banks for Time-Frequency Channel Diagonalization

    Science.gov (United States)

    Ju, Ziyang; Hunziker, Thomas; Dahlhaus, Dirk

    2010-12-01

    We adopt the concept of channel diagonalization to time-frequency signal expansions obtained by DFT filter banks. As a generalization of the frequency domain channel representation used by conventional orthogonal frequency-division multiplexing receivers, the time-frequency domain channel diagonalization can be applied to time-variant channels and aperiodic signals. An inherent error in the case of doubly dispersive channels can be limited by choosing adequate windows underlying the filter banks. We derive a formula for the mean-squared sample error in the case of wide-sense stationary uncorrelated scattering (WSSUS) channels, which serves as objective function in the window optimization. Furthermore, an enhanced scheme for the parameterization of tight Gabor frames enables us to constrain the window in order to define paraunitary filter banks. We show that the design of windows optimized for WSSUS channels with known statistical properties can be formulated as a convex optimization problem. The performance of the resulting windows is investigated under different channel conditions, for different oversampling factors, and compared against the performance of alternative windows. Finally, a generic matched filter receiver incorporating the proposed channel diagonalization is discussed which may be essential for future reconfigurable radio systems.

  8. Optimized Paraunitary Filter Banks for Time-Frequency Channel Diagonalization

    Directory of Open Access Journals (Sweden)

    Ju Ziyang

    2010-01-01

    Full Text Available We adopt the concept of channel diagonalization to time-frequency signal expansions obtained by DFT filter banks. As a generalization of the frequency domain channel representation used by conventional orthogonal frequency-division multiplexing receivers, the time-frequency domain channel diagonalization can be applied to time-variant channels and aperiodic signals. An inherent error in the case of doubly dispersive channels can be limited by choosing adequate windows underlying the filter banks. We derive a formula for the mean-squared sample error in the case of wide-sense stationary uncorrelated scattering (WSSUS channels, which serves as objective function in the window optimization. Furthermore, an enhanced scheme for the parameterization of tight Gabor frames enables us to constrain the window in order to define paraunitary filter banks. We show that the design of windows optimized for WSSUS channels with known statistical properties can be formulated as a convex optimization problem. The performance of the resulting windows is investigated under different channel conditions, for different oversampling factors, and compared against the performance of alternative windows. Finally, a generic matched filter receiver incorporating the proposed channel diagonalization is discussed which may be essential for future reconfigurable radio systems.

  9. A checklist for endonasal transsphenoidal anterior skull base surgery.

    Science.gov (United States)

    Laws, Edward R; Wong, Judith M; Smith, Timothy R; de Los Reyes, Kenneth; Aglio, Linda S; Thorne, Alison J; Cote, David J; Esposito, Felice; Cappabianca, Paolo; Gawande, Atul

    2016-06-01

    OBJECT Approximately 250 million surgical procedures are performed annually worldwide, and data suggest that major complications occur in 3%-17% of them. Many of these complications can be classified as avoidable, and previous studies have demonstrated that preoperative checklists improve operating room teamwork and decrease complication rates. Although the authors' institution has instituted a general preoperative "time-out" designed to streamline communication, flatten vertical authority gradients, and decrease procedural errors, there is no specific checklist for transnasal transsphenoidal anterior skull base surgery, with or without endoscopy. Such minimally invasive cranial surgery uses a completely different conceptual approach, set-up, instrumentation, and operative procedure. Therefore, it can be associated with different types of complications as compared with open cranial surgery. The authors hypothesized that a detailed, procedure-specific, preoperative checklist would be useful to reduce errors, improve outcomes, decrease delays, and maximize both teambuilding and operational efficiency. Thus, the object of this study was to develop such a checklist for endonasal transsphenoidal anterior skull base surgery. METHODS An expert panel was convened that consisted of all members of the typical surgical team for transsphenoidal endoscopic cases: neurosurgeons, anesthesiologists, circulating nurses, scrub technicians, surgical operations managers, and technical assistants. Beginning with a general checklist, procedure-specific items were added and categorized into 4 pauses: Anesthesia Pause, Surgical Pause, Equipment Pause, and Closure Pause. RESULTS The final endonasal transsphenoidal anterior skull base surgery checklist is composed of the following 4 pauses. The Anesthesia Pause consists of patient identification, diagnosis, pertinent laboratory studies, medications, surgical preparation, patient positioning, intravenous/arterial access, fluid management

  10. Optimal Stochastic Restart Renders Fluctuations in First Passage Times Universal

    Science.gov (United States)

    Reuveni, Shlomi

    2016-04-01

    Stochastic restart may drastically reduce the expected run time of a computer algorithm, expedite the completion of a complex search process, or increase the turnover rate of an enzymatic reaction. These diverse first-passage-time (FPT) processes seem to have very little in common but it is actually quite the other way around. Here we show that the relative standard deviation associated with the FPT of an optimally restarted process, i.e., one that is restarted at a constant (nonzero) rate which brings the mean FPT to a minimum, is always unity. We interpret, further generalize, and discuss this finding and the implications arising from it.

  11. Chaos Time Series Prediction Based on Membrane Optimization Algorithms

    Directory of Open Access Journals (Sweden)

    Meng Li

    2015-01-01

    Full Text Available This paper puts forward a prediction model based on membrane computing optimization algorithm for chaos time series; the model optimizes simultaneously the parameters of phase space reconstruction (τ,m and least squares support vector machine (LS-SVM (γ,σ by using membrane computing optimization algorithm. It is an important basis for spectrum management to predict accurately the change trend of parameters in the electromagnetic environment, which can help decision makers to adopt an optimal action. Then, the model presented in this paper is used to forecast band occupancy rate of frequency modulation (FM broadcasting band and interphone band. To show the applicability and superiority of the proposed model, this paper will compare the forecast model presented in it with conventional similar models. The experimental results show that whether single-step prediction or multistep prediction, the proposed model performs best based on three error measures, namely, normalized mean square error (NMSE, root mean square error (RMSE, and mean absolute percentage error (MAPE.

  12. Optimal Cotton Insecticide Application Termination Timing: A Meta-Analysis.

    Science.gov (United States)

    Griffin, T W; Zapata, S D

    2016-08-01

    The concept of insecticide termination timing is generally accepted among cotton (Gossypium hirsutum) researchers; however, exact timings are often disputed. Specifically, there is uncertainty regarding the last economic insecticide application to control fruit-feeding pests including tarnished plant bug (Lygus lineolaris (Palisot de Beauvois)), boll weevil (Anthonomus grandis), bollworm (Helicoverpa zea), tobacco budworm (Heliothis virescens), and cotton fleahopper (Pseudatomoscelis seriatus). A systematic review of prior studies was conducted within a meta-analytic framework. Nine publicly available articles were amalgamated to develop an optimal timing principle. These prior studies reported 53 independent multiple means comparison field experiments for a total of 247 trial observations. Stochastic plateau theory integrated with econometric meta-analysis methodology was applied to the meta-database to determine the shape of the functional form of both the agronomic optimal insecticide termination timing and corresponding yield potential. Results indicated that current university insecticide termination timing recommendations are later than overall estimated timing suggested. The estimated 159 heat units (HU) after the fifth position above white flower (NAWF5) was found to be statistically different than the 194 HU termination used as the status quo recommended termination timing. Insecticides applied after 159 HU may have been applied in excess, resulting in unnecessary economic and environmental costs. Empirical results also suggested that extending the insecticide termination time by one unit resulted in a cotton lint yield increase of 0.27 kilograms per hectare up to the timing where the plateau began. Based on economic analyses, profit-maximizing producers may cease application as soon as 124 HU after NAWF5. These results provided insights useful to improve production systems by applying inputs only when benefits were expected to be in excess of the

  13. Optimal Cotton Insecticide Application Termination Timing: A Meta-Analysis.

    Science.gov (United States)

    Griffin, T W; Zapata, S D

    2016-08-01

    The concept of insecticide termination timing is generally accepted among cotton (Gossypium hirsutum) researchers; however, exact timings are often disputed. Specifically, there is uncertainty regarding the last economic insecticide application to control fruit-feeding pests including tarnished plant bug (Lygus lineolaris (Palisot de Beauvois)), boll weevil (Anthonomus grandis), bollworm (Helicoverpa zea), tobacco budworm (Heliothis virescens), and cotton fleahopper (Pseudatomoscelis seriatus). A systematic review of prior studies was conducted within a meta-analytic framework. Nine publicly available articles were amalgamated to develop an optimal timing principle. These prior studies reported 53 independent multiple means comparison field experiments for a total of 247 trial observations. Stochastic plateau theory integrated with econometric meta-analysis methodology was applied to the meta-database to determine the shape of the functional form of both the agronomic optimal insecticide termination timing and corresponding yield potential. Results indicated that current university insecticide termination timing recommendations are later than overall estimated timing suggested. The estimated 159 heat units (HU) after the fifth position above white flower (NAWF5) was found to be statistically different than the 194 HU termination used as the status quo recommended termination timing. Insecticides applied after 159 HU may have been applied in excess, resulting in unnecessary economic and environmental costs. Empirical results also suggested that extending the insecticide termination time by one unit resulted in a cotton lint yield increase of 0.27 kilograms per hectare up to the timing where the plateau began. Based on economic analyses, profit-maximizing producers may cease application as soon as 124 HU after NAWF5. These results provided insights useful to improve production systems by applying inputs only when benefits were expected to be in excess of the

  14. The Optimal Timing of Adoption of a Green Technology

    International Nuclear Information System (INIS)

    We study the optimal timing of adoption of a cleaner technology and its effects on the rate of growth of an economy in the context of an AK endogenous growth model. We show that the results depend upon the behavior of the marginal utility of environmental quality with respect to consumption. When it is increasing, we derive the capital level at the optimal timing of adoption. We show that this capital threshold is independent of the initial conditions on the stock of capital, implying that capital-poor countries tend to take longer to adopt. Also, country-specific characteristics, as the existence of high barriers to adoption, may lead to different capital thresholds for different countries. If the marginal utility of environmental quality decreases with consumption, a country should never delay adoption; the optimal policy is either to adopt immediately or, if adoption costs are too high, to never adopt. The policy implications of these results are discussed in the context of the international debate surrounding the environmental political agenda

  15. The Optimal Timing of Adoption of a Green Technology

    Energy Technology Data Exchange (ETDEWEB)

    Cunha-e-Sa, M.A.; Reis, A.B. [Faculdade de Economia, Universidade Nova de Lisboa, Campus de Campolide, P-1099-032 Lisbon (Portugal)

    2007-01-15

    We study the optimal timing of adoption of a cleaner technology and its effects on the rate of growth of an economy in the context of an AK endogenous growth model. We show that the results depend upon the behavior of the marginal utility of environmental quality with respect to consumption. When it is increasing, we derive the capital level at the optimal timing of adoption. We show that this capital threshold is independent of the initial conditions on the stock of capital, implying that capital-poor countries tend to take longer to adopt. Also, country-specific characteristics, as the existence of high barriers to adoption, may lead to different capital thresholds for different countries. If the marginal utility of environmental quality decreases with consumption, a country should never delay adoption; the optimal policy is either to adopt immediately or, if adoption costs are {sup t}oo high{sup ,} to never adopt. The policy implications of these results are discussed in the context of the international debate surrounding the environmental political agenda.

  16. Optimal trading strategies—a time series approach

    Science.gov (United States)

    Bebbington, Peter A.; Kühn, Reimer

    2016-05-01

    Motivated by recent advances in the spectral theory of auto-covariance matrices, we are led to revisit a reformulation of Markowitz’ mean-variance portfolio optimization approach in the time domain. In its simplest incarnation it applies to a single traded asset and allows an optimal trading strategy to be found which—for a given return—is minimally exposed to market price fluctuations. The model is initially investigated for a range of synthetic price processes, taken to be either second order stationary, or to exhibit second order stationary increments. Attention is paid to consequences of estimating auto-covariance matrices from small finite samples, and auto-covariance matrix cleaning strategies to mitigate against these are investigated. Finally we apply our framework to real world data.

  17. Optimal transmissions for space-time coded OFDM UWB systems

    Institute of Scientific and Technical Information of China (English)

    WANG Jun-fang; ZHU Guang-xi; JIN Jiang

    2005-01-01

    The emerging ultra-wideband (UWB) system offers a great potential for the design of high-speed short-range communications. Compared with great progress at physical layer, the corresponding medium access control (MAC) layer designs are naturally placed on the schedules. We focus on the optimal power load scheme, which is an integral part of the MAC layer protocol design, for UWB space-time coded (STC) orthogonal frequency-division multiplexing (OFDM)transmissions. Assumed the transmitter has perfect or partial channel stage information (CSI). Based on the optimization criteria of maximizing capacity, three kinds of power load schemes were presented with different tradeoff among performance, complexity and feedback bandwidth overhead. The proposed schemes are verified and compared under the channel prototype proposed by IEEE 802.15.3a Task Group.

  18. Discrete Time Optimal Adaptive Control for Linear Stochastic Systems

    Institute of Scientific and Technical Information of China (English)

    JIANG Rui; LUO Guiming

    2007-01-01

    The least-squares(LS)algorithm has been used for system modeling for a long time. Without any excitation conditions, only the convergence rate of the common LS algorithm can be obtained. This paper analyzed the weighted least-squares(WLS)algorithm and described the good properties of the WLS algorithm. The WLS algorithm was then used for daptive control of linear stochastic systems to show that the linear closed-loop system was globally stable and that the system identification was consistent. Compared to the past optimal adaptive controller,this controller does not impose restricted conditions on the coefficients of the system, such as knowing the first coefficient before the controller. Without any persistent excitation conditions, the analysis shows that, with the regulation of the adaptive control, the closed-loop system was globally stable and the adaptive controller converged to the one-step-ahead optimal controller in some sense.

  19. A Novel Real-time Optimization Methodology for Chemical Plants

    Institute of Scientific and Technical Information of China (English)

    黄静雯; 李宏光

    2012-01-01

    In this paper, a novel approach termed process goose queue (PGQ) is suggested to deal with real-time optimization (RTO) of chemical plants. Taking advantage of the ad-hoc structure of PGQ which imitates biologic nature of flying wild geese, a chemical plant optimization problem can be re-formulated as a combination of a multi-layer PGQ and a PGQ-Objective according to the relationship among process variables involved in the objective and constraints. Subsequently, chemical plant RTO solutions are converted into coordination issues among PGQs which could be dealt with in a novel way. Accordingly, theoretical definitions, adjustment rule and implementing procedures associated with the approach are explicitly introduced together with corresponding enabling algorithms. Finally, an exemplary chemical plant is employed to demonstrate the feasibility and validity of the contribution.

  20. Development and Pilot of a Checklist for Management of Acute Liver Failure in the Intensive Care Unit.

    Directory of Open Access Journals (Sweden)

    Oren K Fix

    Full Text Available Acute liver failure (ALF is an ideal condition for use of a checklist. Our aims were to develop a checklist for the management of ALF in the intensive care unit (ICU and assess the usability of the checklist among multiple providers.The initial checklist was developed from published guidelines and expert opinion. The checklist underwent pilot testing at 11 academic liver transplant centers in the US and Canada. An anonymous, written survey was used to assess the usability and quality of the checklist. Written comments were used to improve the checklist following the pilot testing period.We received 81 surveys involving the management of 116 patients during the pilot testing period. The overall quality of the checklist was judged to be above average to excellent by 94% of users. On a 5-point Likert scale, the majority of survey respondents agreed or agreed strongly with the following checklist characteristics: the checklist was easy to read (99% agreed/agreed strongly, easy to use (97%, items are categorized logically (98%, time to complete the checklist did not interfere with delivery of appropriate and safe patient care (94% and was not excessively burdensome (92%, the checklist allowed the user the freedom to use his or her clinical judgment (80%, it is a useful tool in the management of acute liver failure (98%. Web-based and mobile apps were developed for use of the checklist at the point of care.The checklist for the management of ALF in the ICU was shown in this pilot study to be easy to use, helpful and accepted by a wide variety of practitioners at multiple sites in the US and Canada.

  1. Retrospective optimization of time-dependent fermentation control strategies using time-independent historical data.

    Science.gov (United States)

    Coleman, Matthew C; Block, David E

    2006-10-20

    We have previously shown the usefulness of historical data for fermentation process optimization. The methodology developed includes identification of important process inputs, training of an artificial neural network (ANN) process model, and ultimately use of the ANN model with a genetic algorithm to find the optimal values of each critical process input. However, this approach ignores the time-dependent nature of the system, and therefore, does not fully utilize the available information within a database. In this work, we propose a method for incorporating time-dependent optimization into our previously developed three-step optimization routine. This is achieved by an additional step that uses a fermentation model (consisting of coupled ordinary differential equations (ODE)) to interpret important time-course features of the collected data through adjustments in model parameters. Important process variables not explicitly included in the model were then identified for each model parameter using automatic relevance determination (ARD) with Gaussian process (GP) models. The developed GP models were then combined with the fermentation model to form a hybrid neural network model that predicted the time-course activity of the cell and protein concentrations of novel fermentation conditions. A hybrid-genetic algorithm was then used in conjunction with the hybrid model to suggest optimal time-dependent control strategies. The presented method was implemented upon an E. coli fermentation database generated in our laboratory. Optimization of two different criteria (final protein yield and a simplified economic criteria) was attempted. While the overall protein yield was not increased using this methodology, we were successful in increasing a simplified economic criterion by 15% compared to what had been previously observed. These process conditions included using 35% less arabinose (the inducer) and 33% less typtone in the media and reducing the time required to reach

  2. Checklist of the Iranian Ground Beetles (Coleoptera; Carabidae).

    Science.gov (United States)

    Azadbakhsh, Saeed; Nozari, Jamasb

    2015-09-30

    An up-to-date checklist of the ground beetles of Iran is presented. Altogether 955 species and subspecies in 155 genera belonging to 26 subfamilies of Carabidae are reported; 25 taxa are recorded for Iran for the fist time. New localities are listed and some previous distributional records are discussed.

  3. Updated checklist of the Eurytomidae (Hymenoptera, Chalcidoidea species of Turkey

    Directory of Open Access Journals (Sweden)

    Çam H.

    2012-01-01

    Full Text Available A checklist of Eurytomidae species known in Turkey is presented for the first time in the present paper, including their distributions in Turkey. A total of 88 species in 8 genera belonging to 2 subfamilies (Eurytominae, Rileyinae are determined. Sycophila mellea Curtis, 1831 is presented as a new record for Turkish fauna.

  4. Opposing selection and environmental variation modify optimal timing of breeding.

    Science.gov (United States)

    Tarwater, Corey E; Beissinger, Steven R

    2013-09-17

    Studies of evolution in wild populations often find that the heritable phenotypic traits of individuals producing the most offspring do not increase proportionally in the population. This paradox may arise when phenotypic traits influence both fecundity and viability and when there is a tradeoff between these fitness components, leading to opposing selection. Such tradeoffs are the foundation of life history theory, but they are rarely investigated in selection studies. Timing of breeding is a classic example of a heritable trait under directional selection that does not result in an evolutionary response. Using a 22-y study of a tropical parrot, we show that opposing viability and fecundity selection on the timing of breeding is common and affects optimal breeding date, defined by maximization of fitness. After accounting for sampling error, the directions of viability (positive) and fecundity (negative) selection were consistent, but the magnitude of selection fluctuated among years. Environmental conditions (rainfall and breeding density) primarily and breeding experience secondarily modified selection, shifting optimal timing among individuals and years. In contrast to other studies, viability selection was as strong as fecundity selection, late-born juveniles had greater survival than early-born juveniles, and breeding later in the year increased fitness under opposing selection. Our findings provide support for life history tradeoffs influencing selection on phenotypic traits, highlight the need to unify selection and life history theory, and illustrate the importance of monitoring survival as well as reproduction for understanding phenological responses to climate change.

  5. Opposing selection and environmental variation modify optimal timing of breeding.

    Science.gov (United States)

    Tarwater, Corey E; Beissinger, Steven R

    2013-09-17

    Studies of evolution in wild populations often find that the heritable phenotypic traits of individuals producing the most offspring do not increase proportionally in the population. This paradox may arise when phenotypic traits influence both fecundity and viability and when there is a tradeoff between these fitness components, leading to opposing selection. Such tradeoffs are the foundation of life history theory, but they are rarely investigated in selection studies. Timing of breeding is a classic example of a heritable trait under directional selection that does not result in an evolutionary response. Using a 22-y study of a tropical parrot, we show that opposing viability and fecundity selection on the timing of breeding is common and affects optimal breeding date, defined by maximization of fitness. After accounting for sampling error, the directions of viability (positive) and fecundity (negative) selection were consistent, but the magnitude of selection fluctuated among years. Environmental conditions (rainfall and breeding density) primarily and breeding experience secondarily modified selection, shifting optimal timing among individuals and years. In contrast to other studies, viability selection was as strong as fecundity selection, late-born juveniles had greater survival than early-born juveniles, and breeding later in the year increased fitness under opposing selection. Our findings provide support for life history tradeoffs influencing selection on phenotypic traits, highlight the need to unify selection and life history theory, and illustrate the importance of monitoring survival as well as reproduction for understanding phenological responses to climate change. PMID:24003118

  6. Exposure time optimization for highly dynamic star trackers.

    Science.gov (United States)

    Wei, Xinguo; Tan, Wei; Li, Jian; Zhang, Guangjun

    2014-01-01

    Under highly dynamic conditions, the star-spots on the image sensor of a star tracker move across many pixels during the exposure time, which will reduce star detection sensitivity and increase star location errors. However, this kind of effect can be compensated well by setting an appropriate exposure time. This paper focuses on how exposure time affects the star tracker under highly dynamic conditions and how to determine the most appropriate exposure time for this case. Firstly, the effect of exposure time on star detection sensitivity is analyzed by establishing the dynamic star-spot imaging model. Then the star location error is deduced based on the error analysis of the sub-pixel centroiding algorithm. Combining these analyses, the effect of exposure time on attitude accuracy is finally determined. Some simulations are carried out to validate these effects, and the results show that there are different optimal exposure times for different angular velocities of a star tracker with a given configuration. In addition, the results of night sky experiments using a real star tracker agree with the simulation results. The summarized regularities in this paper should prove helpful in the system design and dynamic performance evaluation of the highly dynamic star trackers. PMID:24618776

  7. Exposure Time Optimization for Highly Dynamic Star Trackers

    Directory of Open Access Journals (Sweden)

    Xinguo Wei

    2014-03-01

    Full Text Available Under highly dynamic conditions, the star-spots on the image sensor of a star tracker move across many pixels during the exposure time, which will reduce star detection sensitivity and increase star location errors. However, this kind of effect can be compensated well by setting an appropriate exposure time. This paper focuses on how exposure time affects the star tracker under highly dynamic conditions and how to determine the most appropriate exposure time for this case. Firstly, the effect of exposure time on star detection sensitivity is analyzed by establishing the dynamic star-spot imaging model. Then the star location error is deduced based on the error analysis of the sub-pixel centroiding algorithm. Combining these analyses, the effect of exposure time on attitude accuracy is finally determined. Some simulations are carried out to validate these effects, and the results show that there are different optimal exposure times for different angular velocities of a star tracker with a given configuration. In addition, the results of night sky experiments using a real star tracker agree with the simulation results. The summarized regularities in this paper should prove helpful in the system design and dynamic performance evaluation of the highly dynamic star trackers.

  8. Optimizing the search for transiting planets in long time series

    CERN Document Server

    Ofir, Aviv

    2013-01-01

    Context: Transit surveys, both ground- and space- based, have already accumulated a large number of light curves that span several years. Aims: The search for transiting planets in these long time series is computationally intensive. We wish to optimize the search for both detection and computational efficiencies. Methods: We assume that the searched systems can be well described by Keplerian orbits. We then propagate the effects of different system parameters to the detection parameters. Results: We show that the frequency information content of the light curve is primarily determined by the duty cycle of the transit signal, and thus the optimal frequency sampling is found to be cubic and not linear. Further optimization is achieved by considering duty-cycle dependent binning of the phased light curve. By using the (standard) BLS one is either rather insensitive to long-period planets, or less sensitive to short-period planets and computationally slower by a significant factor of ~330 (for a 3yr long dataset...

  9. Time and volume based optimal pricing strategies for telecommunication networks

    OpenAIRE

    Kasap, Nihat

    2008-01-01

    In the recent past, there have been several initiatives by major network providers such as Turk Telekom lead the industry towards network capacity distribution in Turkey. In this study, we use a monopoly pricing model to examine the optimal pricing strategies for “pay-per-volume” and “pay-per-time” based leasing of data networks. Traditionally, network capacity distribution includes short/long term bandwidth and/or usage time leasing. Each consumer has a choice to select volume based pricing ...

  10. Time Optimal Synchronization Procedure and Associated Feedback Loops

    CERN Document Server

    Angoletta, Maria Elena; CERN. Geneva. ATS Department

    2016-01-01

    A procedure to increase the speed of currently used synchronization loops in a synchrotron by an order of magnitude is presented. Beams dynamics constraint imposes an upper limit on excursions in stable phase angle, and the procedure presented exploits this limit to arrive in the synchronized state from an arbitrary initial state in the fastest possible way. Detailed corrector design for beam phase loop, differential frequency loop and final synchronization loop is also presented. Finally, an overview of the synchronization methods currently deployed in some other CERN’s machines is provided, together with a brief comparison with the newly proposed time-optimal algorithm.

  11. NEW DESIGN OF ROBUST OPTIMAL ARBITRARY TIME-DELAY FILTER

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaojun; SHAO Huihe

    2007-01-01

    Zero placement method in the frequency domain is utilized to design robust multi-hump EI optimal arbitrary time-delay filter (OATF) by placing two or more filter zeros near the system poles. A total insensitive OATF can be also achieved if the problem of insensitivity to damping errors is considered. This design strategy is easier to derive and implement. Applications in the anti-swing control of overhead cranes verify the fine performance of this strategy. A better suppression of the load vibrations is obtained using the proposed new OATF, which is more robust to the variation of the cable length.

  12. 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

  13. Thermal lens spectrometry: Optimizing amplitude and shortening the transient time

    Science.gov (United States)

    Silva, Rubens; de Araújo, Marcos A. C.; Jali, Pedro; Moreira, Sanclayton G. C.; Alcantara, Petrus; de Oliveira, Paulo C.

    2011-06-01

    Based on a model introduced by Shen et al. for cw laser induced mode-mismatched dual-beam thermal lens spectrometry (TLS), we explore the parameters related with the geometry of the laser beams and the experimental apparatus that influence the amplitude and time evolution of the transient thermal lens (TL) signal. By keeping the sample cell at the minimum waist of the excitation beam, our results show that high amplitude TL signals, very close to the optimized value, combined with short transient times may be obtained by reducing the curvature radius of the probe beam and the distance between the sample cell and the detector. We also derive an expression for the thermal diffusivity which is independent of the excitation laser beam waist, considerably improving the accuracy of the measurements. The sample used in the experiments was oleic acid, which is present in most of the vegetable oils and is very transparent in the visible spectral range.

  14. Thermal lens spectrometry: Optimizing amplitude and shortening the transient time

    Directory of Open Access Journals (Sweden)

    Rubens Silva

    2011-06-01

    Full Text Available Based on a model introduced by Shen et al. for cw laser induced mode-mismatched dual-beam thermal lens spectrometry (TLS, we explore the parameters related with the geometry of the laser beams and the experimental apparatus that influence the amplitude and time evolution of the transient thermal lens (TL signal. By keeping the sample cell at the minimum waist of the excitation beam, our results show that high amplitude TL signals, very close to the optimized value, combined with short transient times may be obtained by reducing the curvature radius of the probe beam and the distance between the sample cell and the detector. We also derive an expression for the thermal diffusivity which is independent of the excitation laser beam waist, considerably improving the accuracy of the measurements. The sample used in the experiments was oleic acid, which is present in most of the vegetable oils and is very transparent in the visible spectral range.

  15. PATIENT SAFETY IN SURGERY: THE QUALITY OF IMPLEMENTATION OF PATIENT SAFETY CHECKLISTS IN A REGIONAL HOSPITAL

    Directory of Open Access Journals (Sweden)

    V. Karyadinata

    2012-09-01

    Full Text Available Introduction. Patient safety and the avoidance of inhospital adverse events is a key focus of clinical practice and medical audit. A large of proportion of medical errors affect surgical patients in the peri-operative setting. Safety checklists have been adopted by the medical profession from the aviation industry as a cheap and reliable method of avoiding errors which arise from complex or stressful situations. Current evidence suggests that the use of periooperative checklists has led to a decrease in surgical morbidity and hospital costs. Aim. To assess the quality of implementation of a modified patient safety checklist in a UK district general hospital. Methods. An observational tool was designed to assess in real time the peri-operative performance of the surgical safety checklist in patients undergoing general surgical, urological or orthopaedic procedures. Initiation of the checklist, duration of performance and staff participation were audited in real time. Results. 338 cases were monitored. Nurses were most active in initiating the safety checklist. The checklist was performed successfully in less than a minute in most cases. 11-24% of staff (according to professional group present in the operating room did not participate in the checklist. Critical safety checks (patient identity and procedure name were performed in all cases across all specialties. Variations were noted in checking other categories, such as deep vein thrombosis (DVT prophylaxis or patient warming. Conclusions. There is still a potential for improving the practice and culture of surgical patient safety activities. Staff training and designation of patient safety leadership roles is needed in increasing compliance and implementation of patient safety mechanism, such as peri-operative checklists. There is significant data to advocate the need to implement patient safety surgical checklists internationally

  16. Time Scale Optimization and the Hunt for Astronomical Cycles in Deep Time Strata

    Science.gov (United States)

    Meyers, Stephen R.

    2016-04-01

    A valuable attribute of astrochronology is the direct link between chronometer and climate change, providing a remarkable opportunity to constrain the evolution of the surficial Earth System. Consequently, the hunt for astronomical cycles in strata has spurred the development of a rich conceptual framework for climatic/oceanographic change, and has allowed exploration of the geologic record with unprecedented temporal resolution. Accompanying these successes, however, has been a persistent skepticism about appropriate astrochronologic testing and circular reasoning: how does one reliably test for astronomical cycles in stratigraphic data, especially when time is poorly constrained? From this perspective, it would seem that the merits and promise of astrochronology (e.g., a geologic time scale measured in ≤400 kyr increments) also serves as its Achilles heel, if the confirmation of such short rhythms defies rigorous statistical testing. To address these statistical challenges in astrochronologic testing, a new approach has been developed that (1) explicitly evaluates time scale uncertainty, (2) is resilient to common problems associated with spectrum confidence level assessment and 'multiple testing', and (3) achieves high statistical power under a wide range of conditions (it can identify astronomical cycles when present in data). Designated TimeOpt (for "time scale optimization"; Meyers 2015), the method employs a probabilistic linear regression model framework to investigate amplitude modulation and frequency ratios (bundling) in stratigraphic data, while simultaneously determining the optimal time scale. This presentation will review the TimeOpt method, and demonstrate how the flexible statistical framework can be further extended to evaluate (and optimize upon) complex sedimentation rate models, enhancing the statistical power of the approach, and addressing the challenge of unsteady sedimentation. Meyers, S. R. (2015), The evaluation of eccentricity

  17. Optimal Selling Time in Stock Market over a Finite Time Horizon

    Institute of Scientific and Technical Information of China (English)

    S.C.P. YAM; S.P. YUNG; W. ZHOU

    2012-01-01

    In this paper,we examine the best time to sell a stock at a price being as close as possible to its highest price over a finite time horizon [0,T],where the stock price is modelled by a geometric Brownian motion and the 'closeness' is measured by the relative error of the stock price to its highest price over [0,T]. More precisely,we want to optimize the expression:V*=sup0≤τ≤T IE[Vτ/MT],where (Vt)t≥0 is a geometric Brownish motion with constant drift α and constant volatility σ > 0,Mt =max0≤s≤t Vs is the running maximum of the stock price,and the supremum is taken over all possible stopping times 0 < τ < Tadapted to the natural filtration (Ft)t≥0 of the stock price.The above problem has been considered by Shiryaev,Xu and Zhou (2008) and Du Toit and Peskir (2009).In this paper we provide an independent proof that when α =1/2σ2,a selling strategy is optimal if and only if it sells the stock either at the terminal time T or at the moment when the stock price hits its maximum price so far.Besides,when α > 1/2σ2,selling the stock at the terminal time T is the unique optimal selling strategy.Our approach to the problem is purely probabilistic and has been inspired by relating the notion of dominant stopping pτ of a stopping time τ to the optimal stopping strategy arisen in the classical "Secretary Problem".

  18. Middle School Physical Education: Good Sport Checklist.

    Science.gov (United States)

    Tenoschok, Mike

    2001-01-01

    Presents a checklist for monitoring middle school students' behavior during athletics. The checklist highlights: sportsmanship (e.g., playing by the rules, being a good loser, and playing fair); respect (refraining from fighting, avoiding alcohol and other drugs, and shaking hands with opponents); and teamwork (practicing hard, not embarrassing…

  19. Psychometric Characteristics of the Aberrant Behavior Checklist.

    Science.gov (United States)

    Aman, Michael G.; And Others

    1985-01-01

    Information is presented on the psychometric characteristics of the Aberrant Behavior Checklist, a measure of psychotropic drug effects. Internal consistency and test-retest reliability of the checklist appeared very good. Interrater reliability was generally in the moderate range. In general, validity was established for most Aberrant Behavior…

  20. FXR LIA Optimization - Time-resolved OTR Emittance Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, J; Ong, M; Wargo, P; LeSage, G

    2005-07-21

    The Flash X-Ray Radiography (FXR) facility at Lawrence Livermore National Laboratory utilizes a high current, long pulse linear induction accelerator to produce high doses of x-ray radiation. Accurate characterization of the transverse beam emittance is required in order to facilitate accelerator modeling and tuning efforts and, ultimately, to optimize the final focus spot size, yielding higher resolution radiographs. In addition to conventional magnet scan, pepper-pot, and multiple screen techniques, optical transition radiation (OTR) has been proven as a useful emittance measurement diagnostic and is particularly well suited to the FXR accelerator. We shall discuss the time-resolved emittance characterization of an induction linac electron beam using OTR, and we will present our experimental apparatus and analysis software. We shall also develop the theoretical background of beam emittance and transition radiation.

  1. FAME Storage Time in an Optimized Natural Antioxidant Mixture

    Directory of Open Access Journals (Sweden)

    Rodolfo Lopes Coppo

    2013-01-01

    Full Text Available The study of B100 biodiesel oxidation stability, and its conservation, is extremely important to control its quality, especially regarding storage. Many spices have shown antioxidant effect and are the targets of study. Knowing the oxidation process in greater detail allows a reliable storage period to be stipulated for the biodiesel without its degradation until the time of use. Results have shown that according to the accelerated stove method, the optimal mixture, composed of 100% of oregano extract, can confer a 535-day shelf life to biodiesel without evident oxidation. According to the results obtained by the Rancimat method, the ideal mixture consists of 100% rosemary, resulting in 483 days of storage. The application of the process variable showed that the accelerated stove method was more suitable to determine oxidative stability of biodiesel.

  2. 1D Grating structures designed by the time domain topology optimization

    DEFF Research Database (Denmark)

    Yang, Lirong; Lavrinenko, Andrei; Sigmund, Ole;

    2008-01-01

    We report on the time domain application of topology optimization to 1D photonic devices. The method is confirmed to converge to the global minimum when optimizing a Bragg grating structure.......We report on the time domain application of topology optimization to 1D photonic devices. The method is confirmed to converge to the global minimum when optimizing a Bragg grating structure....

  3. Minimal and non-minimal optimal fixed-order compensators for time-varying discrete-time systems

    NARCIS (Netherlands)

    Willigenburg, van L.G.; Koning, de W.L.

    2002-01-01

    The finite horizon optimal fixed-order LQG compensation problem for time-varying discrete-time systems is considered. Using the minimality property of finite horizon time-varying compensators, established in this paper, strengthened discrete-time optimal projection equations and associated boundary

  4. Distributed convex optimization via continuous-time coordination algorithms with discrete-time communication

    OpenAIRE

    Kia, Solmaz S.; Cortes, Jorge; Martinez, Sonia

    2014-01-01

    This paper proposes a novel class of distributed continuous-time coordination algorithms to solve network optimization problems whose cost function is a sum of local cost functions associated to the individual agents. We establish the exponential convergence of the proposed algorithm under (i) strongly connected and weight-balanced digraph topologies when the local costs are strongly convex with globally Lipschitz gradients, and (ii) connected graph topologies when the local costs are strongl...

  5. Optimal Planet Properties For Plate Tectonics Through Time And Space

    Science.gov (United States)

    Stamenkovic, Vlada; Seager, Sara

    2014-11-01

    Both the time and the location of planet formation shape a rocky planet’s mass, interior composition and structure, and hence also its tectonic mode. The tectonic mode of a planet can vary between two end-member solutions, plate tectonics and stagnant lid convection, and does significantly impact outgassing and biogeochemical cycles on any rocky planet. Therefore, estimating how the tectonic mode of a planet is affected by a planet’s age, mass, structure, and composition is a major step towards understanding habitability of exoplanets and geophysical false positives to biosignature gases. We connect geophysics to astronomy in order to understand how we could identify and where we could find planet candidates with optimal conditions for plate tectonics. To achieve this goal, we use thermal evolution models, account for the current wide range of uncertainties, and simulate various alien planets. Based on our best model estimates, we predict that the ideal targets for plate tectonics are oxygen-dominated (C/Ometallic cores super-Mercury, rocky body densities of ~7000kgm-3), and with small mantle concentrations of iron 0%), water 0%), and radiogenic isotopes 10 times less than Earth). Super-Earths, undifferentiated planets, and especially hypothetical carbon planets, speculated to consist of SiC and C, are not optimal for the occurrence of plate tectonics. These results put Earth close to an ideal compositional and structural configuration for plate tectonics. Moreover, the results indicate that plate tectonics might have never existed on planets formed soon after the Big Bang—but instead is favored on planets formed from an evolved interstellar medium enriched in iron but depleted in silicon, oxygen, and especially in Th, K, and U relative to iron. This possibly sets a belated Galactic start for complex Earth-like surface life if plate tectonics significantly impacts the build up and regulation of gases relevant for life. This allows for the first time to

  6. Inversion of generalized relaxation time distributions with optimized damping parameter

    Science.gov (United States)

    Florsch, Nicolas; Revil, André; Camerlynck, Christian

    2014-10-01

    Retrieving the Relaxation Time Distribution (RDT), the Grains Size Distribution (GSD) or the Pore Size Distribution (PSD) from low-frequency impedance spectra is a major goal in geophysics. The “Generalized RTD” generalizes parametric models like Cole-Cole and many others, but remains tricky to invert since this inverse problem is ill-posed. We propose to use generalized relaxation basis function (for instance by decomposing the spectra on basis of generalized Cole-Cole relaxation elements instead of the classical Debye basis) and to use the L-curve approach to optimize the damping parameter required to get smooth and realistic inverse solutions. We apply our algorithm to three examples, one synthetic and two real data sets, and the program includes the possibility of converting the RTD into GSD or PSD by choosing the value of the constant connecting the relaxation time to the characteristic polarization size of interest. A high frequencies (typically above 1 kHz), a dielectric term in taken into account in the model. The code is provided as an open Matlab source as a supplementary file associated with this paper.

  7. Design Time Optimization for Hardware Watermarking Protection of HDL Designs

    Directory of Open Access Journals (Sweden)

    E. Castillo

    2015-01-01

    Full Text Available HDL-level design offers important advantages for the application of watermarking to IP cores, but its complexity also requires tools automating these watermarking algorithms. A new tool for signature distribution through combinational logic is proposed in this work. IPP@HDL, a previously proposed high-level watermarking technique, has been employed for evaluating the tool. IPP@HDL relies on spreading the bits of a digital signature at the HDL design level using combinational logic included within the original system. The development of this new tool for the signature distribution has not only extended and eased the applicability of this IPP technique, but it has also improved the signature hosting process itself. Three algorithms were studied in order to develop this automated tool. The selection of a cost function determines the best hosting solutions in terms of area and performance penalties on the IP core to protect. An 1D-DWT core and MD5 and SHA1 digital signatures were used in order to illustrate the benefits of the new tool and its optimization related to the extraction logic resources. Among the proposed algorithms, the alternative based on simulated annealing reduces the additional resources while maintaining an acceptable computation time and also saving designer effort and time.

  8. Design time optimization for hardware watermarking protection of HDL designs.

    Science.gov (United States)

    Castillo, E; Morales, D P; García, A; Parrilla, L; Todorovich, E; Meyer-Baese, U

    2015-01-01

    HDL-level design offers important advantages for the application of watermarking to IP cores, but its complexity also requires tools automating these watermarking algorithms. A new tool for signature distribution through combinational logic is proposed in this work. IPP@HDL, a previously proposed high-level watermarking technique, has been employed for evaluating the tool. IPP@HDL relies on spreading the bits of a digital signature at the HDL design level using combinational logic included within the original system. The development of this new tool for the signature distribution has not only extended and eased the applicability of this IPP technique, but it has also improved the signature hosting process itself. Three algorithms were studied in order to develop this automated tool. The selection of a cost function determines the best hosting solutions in terms of area and performance penalties on the IP core to protect. An 1D-DWT core and MD5 and SHA1 digital signatures were used in order to illustrate the benefits of the new tool and its optimization related to the extraction logic resources. Among the proposed algorithms, the alternative based on simulated annealing reduces the additional resources while maintaining an acceptable computation time and also saving designer effort and time.

  9. Multibeam Satellite Frequency/Time Duality Study and Capacity Optimization

    CERN Document Server

    Lei, Jiang

    2011-01-01

    In this paper, we investigate two new candidate transmission schemes, Non-Orthogonal Frequency Reuse (NOFR) and Beam-Hoping (BH). They operate in different domains (frequency and time/space, respectively), and we want to know which domain shows overall best performance. We propose a novel formulation of the Signal-to-Interference plus Noise Ratio (SINR) which allows us to prove the frequency/time duality of these schemes. Further, we propose two novel capacity optimization approaches assuming per-beam SINR constraints in order to use the satellite resources (e.g. power and bandwidth) more efficiently. Moreover, we develop a general methodology to include technological constraints due to realistic implementations, and obtain the main factors that prevent the two technologies dual of each other in practice, and formulate the technological gap between them. The Shannon capacity (upper bound) and current state-of-the-art coding and modulations are analyzed in order to quantify the gap and to evaluate the performa...

  10. Design time optimization for hardware watermarking protection of HDL designs.

    Science.gov (United States)

    Castillo, E; Morales, D P; García, A; Parrilla, L; Todorovich, E; Meyer-Baese, U

    2015-01-01

    HDL-level design offers important advantages for the application of watermarking to IP cores, but its complexity also requires tools automating these watermarking algorithms. A new tool for signature distribution through combinational logic is proposed in this work. IPP@HDL, a previously proposed high-level watermarking technique, has been employed for evaluating the tool. IPP@HDL relies on spreading the bits of a digital signature at the HDL design level using combinational logic included within the original system. The development of this new tool for the signature distribution has not only extended and eased the applicability of this IPP technique, but it has also improved the signature hosting process itself. Three algorithms were studied in order to develop this automated tool. The selection of a cost function determines the best hosting solutions in terms of area and performance penalties on the IP core to protect. An 1D-DWT core and MD5 and SHA1 digital signatures were used in order to illustrate the benefits of the new tool and its optimization related to the extraction logic resources. Among the proposed algorithms, the alternative based on simulated annealing reduces the additional resources while maintaining an acceptable computation time and also saving designer effort and time. PMID:25861681

  11. Using checklists and algorithms to improve qualitative exposure judgment accuracy.

    Science.gov (United States)

    Arnold, Susan F; Stenzel, Mark; Drolet, Daniel; Ramachandran, Gurumurthy

    2016-01-01

    Most exposure assessments are conducted without the aid of robust personal exposure data and are based instead on qualitative inputs such as education and experience, training, documentation on the process chemicals, tasks and equipment, and other information. Qualitative assessments determine whether there is any follow-up, and influence the type that occurs, such as quantitative sampling, worker training, and implementing exposure and risk management measures. Accurate qualitative exposure judgments ensure appropriate follow-up that in turn ensures appropriate exposure management. Studies suggest that qualitative judgment accuracy is low. A qualitative exposure assessment Checklist tool was developed to guide the application of a set of heuristics to aid decision making. Practicing hygienists (n = 39) and novice industrial hygienists (n = 8) were recruited for a study evaluating the influence of the Checklist on exposure judgment accuracy. Participants generated 85 pre-training judgments and 195 Checklist-guided judgments. Pre-training judgment accuracy was low (33%) and not statistically significantly different from random chance. A tendency for IHs to underestimate the true exposure was observed. Exposure judgment accuracy improved significantly (p Qualitative judgments guided by the Checklist tool were categorically accurate or over-estimated the true exposure by one category 70% of the time. The overall magnitude of exposure judgment precision also improved following training. Fleiss' κ, evaluating inter-rater agreement between novice assessors was fair to moderate (κ = 0.39). Cohen's weighted and unweighted κ were good to excellent for novice (0.77 and 0.80) and practicing IHs (0.73 and 0.89), respectively. Checklist judgment accuracy was similar to quantitative exposure judgment accuracy observed in studies of similar design using personal exposure measurements, suggesting that the tool could be useful in developing informed priors and further

  12. On selection of the optimal data time interval for real-time hydrological forecasting

    Directory of Open Access Journals (Sweden)

    J. Liu

    2012-09-01

    Full Text Available With the advancement in modern telemetry and communication technologies, hydrological data can be collected with an increasingly higher sampling rate. An important issue deserving attention from the hydrological community is what suitable time interval of the model input data should be chosen in hydrological forecasting. Such a problem has long been recognised in the control engineering community but is a largely ignored topic in operational applications of hydrological forecasting. In this study, the intrinsic properties of rainfall-runoff data with different time intervals are first investigated from the perspectives of the sampling theorem and the information loss using the discrete wavelet decomposition tool. It is found that rainfall signals with very high sampling rates may not always improve the accuracy of rainfall-runoff modelling due to the catchment low-pass filtering effect. To further investigate the impact of data time interval in real-time forecasting, a real-time forecasting system is constructed by incorporating the Probability Distributed Model (PDM with a real-time updating scheme, the autoregressive-moving average (ARMA model. Case studies are then carried out on four UK catchments with different concentration times for real-time flow forecasting using data with different time intervals of 15 min, 30 min, 45 min, 60 min, 90 min and 120 min. A positive relation is found between the forecast lead time and the optimal choice of the data time interval, which is also highly dependent on the catchment concentration time. Finally, based on the conclusions from the case studies, a hypothetical pattern is proposed in three-dimensional coordinates to describe the general impact of the data time interval and to provide implications on the selection of the optimal time interval in real-time hydrological forecasting. Although nowadays most operational hydrological systems still have low data sampling rates (daily or hourly, the trend in

  13. Time domain topology optimization of 3D nanophotonic devices

    DEFF Research Database (Denmark)

    Elesin, Yuriy; Lazarov, Boyan Stefanov; Jensen, Jakob Søndergaard;

    2014-01-01

    We present an efficient parallel topology optimization framework for design of large scale 3D nanophotonic devices. The code shows excellent scalability and is demonstrated for optimization of broadband frequency splitter, waveguide intersection, photonic crystal-based waveguide and nanowire-base......-based waveguide. The obtained results are compared to simplified 2D studies and we demonstrate that 3D topology optimization may lead to significant performance improvements. © 2013 Elsevier B.V. All rights reserved....

  14. Measuring fluctuations in paranoia: Validity and psychometric properties of brief state versions of the Paranoia Checklist.

    Science.gov (United States)

    Schlier, Björn; Moritz, Steffen; Lincoln, Tania M

    2016-07-30

    Research increasingly assesses momentary changes in paranoia in order to elucidate causal mechanisms. Observed or manipulated changes in postulated causal factors should result in fluctuations in state paranoid ideation. Previous studies often employed a state-adapted Paranoia Checklist (Freeman et al., 2005) to measure state paranoia. This study examined whether the Paranoia Checklist or subsets of its items are appropriate for this purpose. Thirteen studies (N=860) were subjected to meta-analyses of each Paranoia Checklist item. We selected items based on (1) whether they showed pre-to-post change in the expected direction and (2) whether this effect was larger in experimental vs. control conditions. All resulting item selections were cross-validated on a hold-out sample (n=1893). Finally, we explored how much variation in paranoia was captured by the state-adapted version in a brief ambulatory assessment study (N=32). A thirteen item State Paranoia Checklist as well as a five item and a three item Brief State Paranoia Checklist were extracted. Cross validation revealed better model fit and increased sensitivity to change. Multilevel analysis indicated 25-30% of the variance in the Brief State Paranoia Checklists to be due to intra-individual daily fluctuations in paranoia. Our analyses produced reliable and valid revised scales. Increases in change sensitivity indicate that future assessment of state paranoia in experimental and ambulatory assessment studies can be optimized by using the revised scales.

  15. Measuring fluctuations in paranoia: Validity and psychometric properties of brief state versions of the Paranoia Checklist.

    Science.gov (United States)

    Schlier, Björn; Moritz, Steffen; Lincoln, Tania M

    2016-07-30

    Research increasingly assesses momentary changes in paranoia in order to elucidate causal mechanisms. Observed or manipulated changes in postulated causal factors should result in fluctuations in state paranoid ideation. Previous studies often employed a state-adapted Paranoia Checklist (Freeman et al., 2005) to measure state paranoia. This study examined whether the Paranoia Checklist or subsets of its items are appropriate for this purpose. Thirteen studies (N=860) were subjected to meta-analyses of each Paranoia Checklist item. We selected items based on (1) whether they showed pre-to-post change in the expected direction and (2) whether this effect was larger in experimental vs. control conditions. All resulting item selections were cross-validated on a hold-out sample (n=1893). Finally, we explored how much variation in paranoia was captured by the state-adapted version in a brief ambulatory assessment study (N=32). A thirteen item State Paranoia Checklist as well as a five item and a three item Brief State Paranoia Checklist were extracted. Cross validation revealed better model fit and increased sensitivity to change. Multilevel analysis indicated 25-30% of the variance in the Brief State Paranoia Checklists to be due to intra-individual daily fluctuations in paranoia. Our analyses produced reliable and valid revised scales. Increases in change sensitivity indicate that future assessment of state paranoia in experimental and ambulatory assessment studies can be optimized by using the revised scales. PMID:27227702

  16. Ruby Lake National Wildlife Refuge wildlife checklist

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Checklist with habitat, season, and abundance codes for wildlife species at Ruby Lake NWR. Includes bird, mammal, amphibian, reptile, and fish species.

  17. Convertible Subordinated Debt Financing and Optimal Investment Timing

    OpenAIRE

    Kyoko Yagi; Ryuta Takashima

    2010-01-01

    In this paper, we examine the optimal investment policy of the firm which is financed by issuing equity, straight debt and convertible debt with the senior-sub structure. The senior-sub structure gives preference to straight debt over convertible debt and to convertible debt over equity when the default occurs. We investigate how the senior-sub structure affects the optimal policies for default, conversion and investment the values of equity, straight debt, convertible debt and investment. In...

  18. A controller based on Optimal Type-2 Fuzzy Logic: systematic design, optimization and real-time implementation.

    Science.gov (United States)

    Fayek, H M; Elamvazuthi, I; Perumal, N; Venkatesh, B

    2014-09-01

    A computationally-efficient systematic procedure to design an Optimal Type-2 Fuzzy Logic Controller (OT2FLC) is proposed. The main scheme is to optimize the gains of the controller using Particle Swarm Optimization (PSO), then optimize only two parameters per type-2 membership function using Genetic Algorithm (GA). The proposed OT2FLC was implemented in real-time to control the position of a DC servomotor, which is part of a robotic arm. The performance judgments were carried out based on the Integral Absolute Error (IAE), as well as the computational cost. Various type-2 defuzzification methods were investigated in real-time. A comparative analysis with an Optimal Type-1 Fuzzy Logic Controller (OT1FLC) and a PI controller, demonstrated OT2FLC׳s superiority; which is evident in handling uncertainty and imprecision induced in the system by means of noise and disturbances.

  19. Optimal timing of hypothermia in relation to myocardial reperfusion.

    Science.gov (United States)

    Götberg, Matthias; van der Pals, Jesper; Götberg, Michael; Olivecrona, Göran K; Kanski, Mikael; Koul, Sasha; Otto, Andreas; Engblom, Henrik; Ugander, Martin; Arheden, Håkan; Erlinge, David

    2011-09-01

    Two previous clinical trials investigating hypothermia as an adjunct therapy for myocardial infarction have failed. Recently a pilot study has demonstrated a significant reduction in infarct size. The aims of this study were to elucidate the effects of hypothermia on reperfusion injury and to investigate the optimal hypothermia protocol for a future clinical trial. Pigs (40-50 kg) were anesthetized and a normal pig temperature of 38°C was established utilizing an endovascular temperature modulating catheter. The pigs were randomized to a combination hypothermia group (1,000 ml of 4°C saline solution and endovascular cooling, n = 8), or to normothermic controls (n = 8). A PCI balloon was then inflated in the LAD for 40 min (control) or 45 min with hypothermia induced during the last 5 min. Furthermore, hypothermia induced by cold saline alone (n = 8), and prolonged combination hypothermia during reperfusion (n = 7) were also examined. Infarct size and area at risk were determined ex vivo after 4 h of reperfusion using gadolinium-enhanced MRI and Tc-99-tetrofosmin SPECT, respectively. All pigs in the combination hypothermia group were cooled to <35°C within 5 min. Combination hypothermia reduced IS/AAR by 18% compared with normothermic controls despite 5 min longer ischemic time (61 ± 5 vs. 74 ± 4%, p = 0.03). Cold saline did not reduce IS/AAR. Prolonging hypothermia treatment after onset of reperfusion by an additional 45 min over that used in a previous paper did not confer any additional benefit. The cardioprotective effects of hypothermia treatment are due to an attenuation of myocardial injury during both ischemia and reperfusion. The results suggest that a hypothermia protocol using a cold saline infusion and endovascular cooling enables hypothermia to be induced in a clinical setting without delaying reperfusion therapy.

  20. Effectiveness of Surgical Safety Checklists in Improving Patient Safety.

    Science.gov (United States)

    Ragusa, Paul S; Bitterman, Adam; Auerbach, Brett; Healy, William A

    2016-01-01

    Wrong-site surgery is all too common. Despite more than a decade of campaigns by major organizations to prevent these events, there are still reports of such mistakes. This article reviews the recent literature on surgical safety checklists and other tools designed to prevent wrong-site surgery and improve patient safety in the operating room. Emphasis is placed on how well institutions comply with these guidelines, the perceptions and attitudes of those who are asked to implement them, and their effectiveness. The literature shows that the implementation of such protocols has improved patient safety. In general, these efforts are viewed favorably by operating room personnel. However, the role of these checklists and other tools in reducing wrong-sided surgeries has not been proven. The goal of the health care profession should be to continue to improve on the advances that have been made in implementing surgical checklists and preventing wrong-site surgery. Practitioners at the authors' institution are continuously searching for ways to improve on the current protocols to prevent wrong-site surgeries. The authors recently employed a protocol in which surgical instruments are kept in the back of the room, away from the patient, until completion of the surgical time-out. This practice helps to ensure that team members are not distracted or preoccupied with setting up equipment during the time-out. This approach also helps to mitigate the hierarchal style in the operating room. PMID:26942472

  1. Optimal experiment design for time-lapse traveltime tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ajo-Franklin, J.B.

    2009-10-01

    Geophysical monitoring techniques offer the only noninvasive approach capable of assessing both the spatial and temporal dynamics of subsurface fluid processes. Increasingly, permanent sensor arrays in boreholes and on the ocean floor are being deployed to improve the repeatability and increase the temporal sampling of monitoring surveys. Because permanent arrays require a large up-front capital investment and are difficult (or impossible) to re-configure once installed, a premium is placed on selecting a geometry capable of imaging the desired target at minimum cost. We present a simple approach to optimizing downhole sensor configurations for monitoring experiments making use of differential seismic traveltimes. In our case, we use a design quality metric based on the accuracy of tomographic reconstructions for a suite of imaging targets. By not requiring an explicit singular value decomposition of the forward operator, evaluation of this objective function scales to problems with a large number of unknowns. We also restrict the design problem by recasting the array geometry into a low dimensional form more suitable for optimization at a reasonable computational cost. We test two search algorithms on the design problem: the Nelder-Mead downhill simplex method and the Multilevel Coordinate Search algorithm. The algorithm is tested for four crosswell acquisition scenarios relevant to continuous seismic monitoring, a two parameter array optimization, several scenarios involving four parameter length/offset optimizations, and a comparison of optimal multi-source designs. In the last case, we also examine trade-offs between source sparsity and the quality of tomographic reconstructions. One general observation is that asymmetric array lengths improve localized image quality in crosswell experiments with a small number of sources and a large number of receivers. Preliminary results also suggest that high-quality differential images can be generated using only a small

  2. Local-in-Time Adjoint-Based Method for Optimal Control/Design Optimization of Unsteady Compressible Flows

    Science.gov (United States)

    Yamaleev, N. K.; Diskin, B.; Nielsen, E. J.

    2009-01-01

    .We study local-in-time adjoint-based methods for minimization of ow matching functionals subject to the 2-D unsteady compressible Euler equations. The key idea of the local-in-time method is to construct a very accurate approximation of the global-in-time adjoint equations and the corresponding sensitivity derivative by using only local information available on each time subinterval. In contrast to conventional time-dependent adjoint-based optimization methods which require backward-in-time integration of the adjoint equations over the entire time interval, the local-in-time method solves local adjoint equations sequentially over each time subinterval. Since each subinterval contains relatively few time steps, the storage cost of the local-in-time method is much lower than that of the global adjoint formulation, thus making the time-dependent optimization feasible for practical applications. The paper presents a detailed comparison of the local- and global-in-time adjoint-based methods for minimization of a tracking functional governed by the Euler equations describing the ow around a circular bump. Our numerical results show that the local-in-time method converges to the same optimal solution obtained with the global counterpart, while drastically reducing the memory cost as compared to the global-in-time adjoint formulation.

  3. An intermediate targets method for time parallelization in optimal control

    CERN Document Server

    Maday, Yvon; Riahi, Kamel

    2011-01-01

    In this paper, we present a method that enables to solve in parallel the Euler-Lagrange system associated with the optimal control of a parabolic equation. Our approach is based on an iterative update of a sequence of intermediate targets and gives rise independent sub-problems that can be solved in parallel. Numerical experiments show the efficiency of our method.

  4. Real-Time Optimization for Economic Model Predictive Control

    DEFF Research Database (Denmark)

    Sokoler, Leo Emil; Edlund, Kristian; Frison, Gianluca;

    2012-01-01

    In this paper, we develop an efficient homogeneous and self-dual interior-point method for the linear programs arising in economic model predictive control. To exploit structure in the optimization problems, the algorithm employs a highly specialized Riccati iteration procedure. Simulations show...

  5. Comparison of Child Behavior Checklist subscales in screening for obsessive-compulsive disorder

    DEFF Research Database (Denmark)

    Andersen, Pia Aaron Skovby; Bilenberg, Niels

    2012-01-01

    Obsessive-compulsive disorder (OCD) is a prevalent psychiatric disorder in children and adolescents associated with significant functional impairment. Early and correct diagnosis is essential for an optimal treatment outcome. The purpose of this study was to determine which of four subscales...... derived from the Child Behavior Checklist best discriminates OCD patients from clinical and population-based controls....

  6. Generalized simulated annealing algorithms using Tsallis statistics : Application to the discrete-time optimal growth problem

    OpenAIRE

    稻垣, 陽介; イナガキ, ヨウスケ; Yousuke, Inagaki

    2007-01-01

    The efficiency of Monte Carlo simulated annealing algorithm based on the generalized statistics of Tsallis (GSA) is compared with conventional simulated annealing (CSA) based on Boltzmann-Gibbs statistics. Application to the discrete-time optimal growth problem demonstrates that the replacement of CSA by GSA has the potential to speed up optimizations with no loss of accuracy in finding optimal policy function.

  7. Turnpike theory of continuous-time linear optimal control problems

    CERN Document Server

    Zaslavski, Alexander J

    2015-01-01

    Individual turnpike results are of great interest due to their numerous applications in engineering and in economic theory; in this book the study is focused on new results of turnpike phenomenon in linear optimal control problems.  The book is intended for engineers as well as for mathematicians interested in the calculus of variations, optimal control, and in applied functional analysis. Two large classes of problems are studied in more depth. The first class studied in Chapter 2 consists of linear control problems with periodic nonsmooth convex integrands. Chapters 3-5 consist of linear control problems with autonomous nonconvex and nonsmooth integrands.  Chapter 6 discusses a turnpike property for dynamic zero-sum games with linear constraints. Chapter 7 examines genericity results. In Chapter 8, the description of structure of variational problems with extended-valued integrands is obtained. Chapter 9 ends the exposition with a study of turnpike phenomenon for dynamic games with extended value integran...

  8. Bayesian Optimization Algorithm, Population Sizing, and Time to Convergence

    Energy Technology Data Exchange (ETDEWEB)

    Pelikan, M.; Goldberg, D.E.; Cantu-Paz, E.

    2000-01-19

    This paper analyzes convergence properties of the Bayesian optimization algorithm (BOA). It settles the BOA into the framework of problem decomposition used frequently in order to model and understand the behavior of simple genetic algorithms. The growth of the population size and the number of generations until convergence with respect to the size of a problem is theoretically analyzed. The theoretical results are supported by a number of experiments.

  9. World checklist of hornworts and liverworts

    Science.gov (United States)

    Söderström, Lars; Hagborg, Anders; von Konrat, Matt; Bartholomew-Began, Sharon; Bell, David; Briscoe, Laura; Brown, Elizabeth; Cargill, D. Christine; Costa, Denise P.; Crandall-Stotler, Barbara J.; Cooper, Endymion D.; Dauphin, Gregorio; Engel, John J.; Feldberg, Kathrin; Glenny, David; Gradstein, S. Robbert; He, Xiaolan; Heinrichs, Jochen; Hentschel, Jörn; Ilkiu-Borges, Anna Luiza; Katagiri, Tomoyuki; Konstantinova, Nadezhda A.; Larraín, Juan; Long, David G.; Nebel, Martin; Pócs, Tamás; Puche, Felisa; Reiner-Drehwald, Elena; Renner, Matt A.M.; Sass-Gyarmati, Andrea; Schäfer-Verwimp, Alfons; Moragues, José Gabriel Segarra; Stotler, Raymond E.; Sukkharak, Phiangphak; Thiers, Barbara M.; Uribe, Jaime; Váňa, Jiří; Villarreal, Juan Carlos; Wigginton, Martin; Zhang, Li; Zhu, Rui-Liang

    2016-01-01

    Abstract A working checklist of accepted taxa worldwide is vital in achieving the goal of developing an online flora of all known plants by 2020 as part of the Global Strategy for Plant Conservation. We here present the first-ever worldwide checklist for liverworts (Marchantiophyta) and hornworts (Anthocerotophyta) that includes 7486 species in 398 genera representing 92 families from the two phyla. The checklist has far reaching implications and applications, including providing a valuable tool for taxonomists and systematists, analyzing phytogeographic and diversity patterns, aiding in the assessment of floristic and taxonomic knowledge, and identifying geographical gaps in our understanding of the global liverwort and hornwort flora. The checklist is derived from a working data set centralizing nomenclature, taxonomy and geography on a global scale. Prior to this effort a lack of centralization has been a major impediment for the study and analysis of species richness, conservation and systematic research at both regional and global scales. The success of this checklist, initiated in 2008, has been underpinned by its community approach involving taxonomic specialists working towards a consensus on taxonomy, nomenclature and distribution. PMID:26929706

  10. World checklist of hornworts and liverworts.

    Science.gov (United States)

    Söderström, Lars; Hagborg, Anders; von Konrat, Matt; Bartholomew-Began, Sharon; Bell, David; Briscoe, Laura; Brown, Elizabeth; Cargill, D Christine; Costa, Denise P; Crandall-Stotler, Barbara J; Cooper, Endymion D; Dauphin, Gregorio; Engel, John J; Feldberg, Kathrin; Glenny, David; Gradstein, S Robbert; He, Xiaolan; Heinrichs, Jochen; Hentschel, Jörn; Ilkiu-Borges, Anna Luiza; Katagiri, Tomoyuki; Konstantinova, Nadezhda A; Larraín, Juan; Long, David G; Nebel, Martin; Pócs, Tamás; Puche, Felisa; Reiner-Drehwald, Elena; Renner, Matt A M; Sass-Gyarmati, Andrea; Schäfer-Verwimp, Alfons; Moragues, José Gabriel Segarra; Stotler, Raymond E; Sukkharak, Phiangphak; Thiers, Barbara M; Uribe, Jaime; Váňa, Jiří; Villarreal, Juan Carlos; Wigginton, Martin; Zhang, Li; Zhu, Rui-Liang

    2016-01-01

    A working checklist of accepted taxa worldwide is vital in achieving the goal of developing an online flora of all known plants by 2020 as part of the Global Strategy for Plant Conservation. We here present the first-ever worldwide checklist for liverworts (Marchantiophyta) and hornworts (Anthocerotophyta) that includes 7486 species in 398 genera representing 92 families from the two phyla. The checklist has far reaching implications and applications, including providing a valuable tool for taxonomists and systematists, analyzing phytogeographic and diversity patterns, aiding in the assessment of floristic and taxonomic knowledge, and identifying geographical gaps in our understanding of the global liverwort and hornwort flora. The checklist is derived from a working data set centralizing nomenclature, taxonomy and geography on a global scale. Prior to this effort a lack of centralization has been a major impediment for the study and analysis of species richness, conservation and systematic research at both regional and global scales. The success of this checklist, initiated in 2008, has been underpinned by its community approach involving taxonomic specialists working towards a consensus on taxonomy, nomenclature and distribution. PMID:26929706

  11. A Glowworm Optimization Method for the Design of Web Services

    Directory of Open Access Journals (Sweden)

    Koffka Khan

    2012-09-01

    Full Text Available A method for adaptive usability evaluation of B2C eCommerce web services is proposed. For measuring eCommerce usability a checklist integrating eCommerce quality and usability is developed. By a Glowworm swarm optimization (GSO neural networks-based model the usability dimensions and their checklist items are adaptively selected. A case study for usability evaluation of an eCommerce anthurium retail website is carried out. The experimental results show that GSO with neural networks supports the allocation of usability problems and the defining of relevant improvement measures. The main advantage of the approach is the adaptive selection of most significant checklist dimensions and items and thus significant reduction of the time for usability evaluation and design.

  12. Feedforward and feedback optimal control for linear time-varying systems with persistent disturbances

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The optimal control problem was studied for linear time-varying systems, which was affected by external persistent disturbances with known dynamic characteristics but unknown initial conditions. To damp the effect of disturbances in an optimal fashion, we obtained a new feedforward and feedback optimal control law and gave the control algorithm by solving a Riccati differential equation and a matrix differential equation. Simulation results showed that the achieved optimal control law was realizable, efficient and robust to reject the external disturbances.

  13. Exposure Time Optimization for Highly Dynamic Star Trackers

    OpenAIRE

    Xinguo Wei; Wei Tan; Jian Li; Guangjun Zhang

    2014-01-01

    Under highly dynamic conditions, the star-spots on the image sensor of a star tracker move across many pixels during the exposure time, which will reduce star detection sensitivity and increase star location errors. However, this kind of effect can be compensated well by setting an appropriate exposure time. This paper focuses on how exposure time affects the star tracker under highly dynamic conditions and how to determine the most appropriate exposure time for this case. Firstly, the effect...

  14. Optimal replacement time estimation for machines and equipment based on cost function

    Directory of Open Access Journals (Sweden)

    J. Šebo

    2013-01-01

    Full Text Available The article deals with a multidisciplinary issue of estimating the optimal replacement time for the machines. Considered categories of machines, for which the optimization method is usable, are of the metallurgical and engineering production. Different models of cost function are considered (both with one and two variables. Parameters of the models were calculated through the least squares method. Models testing show that all are good enough, so for estimation of optimal replacement time is sufficient to use simpler models. In addition to the testing of models we developed the method (tested on selected simple model which enable us in actual real time (with limited data set to indicate the optimal replacement time. The indicated time moment is close enough to the optimal replacement time t*.

  15. Optimal Control of (Min,+) Linear Time-Varying Systems

    OpenAIRE

    Lahaye, Sébastien; Boimond, Jean-Louis; Hardouin, Laurent

    1999-01-01

    International audience The class of discrete event dynamic systems involving only synchronization phenomena can be seen as linear time-invariant systems in a particular algebraic structure called (min,+) algebra. In the same framework, this paper deals with linear time-varying systems, that is, systems whose parameters may change as functions of time. For example, in a manufacturing system the number of working machines, or the number of trains running in a closed network of railway connec...

  16. Optimal replacement time estimation for machines and equipment based on cost function

    OpenAIRE

    J. Šebo; J. Buša; Demeč, P.; J. Svetlík

    2013-01-01

    The article deals with a multidisciplinary issue of estimating the optimal replacement time for the machines. Considered categories of machines, for which the optimization method is usable, are of the metallurgical and engineering production. Different models of cost function are considered (both with one and two variables). Parameters of the models were calculated through the least squares method. Models testing show that all are good enough, so for estimation of optimal replacement time is ...

  17. Approximate Range Emptiness in Constant Time and Optimal Space

    DEFF Research Database (Denmark)

    Goswami, Mayank; Jørgensen, Allan Grønlund; Larsen, Kasper Green;

    2015-01-01

    that the query time can be improved greatly, to constant time, while matching our space lower bound up to a lower order additive term. This result is achieved through a succinct data structure for (non-approximate 1d) range emptiness/reporting queries, which may be of independent interest....

  18. Pseudospectral method based trajectory optimization and fairing rejection time analysis of solid launch vehicle

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The problem of real-time trajectory optimization for small solid launch vehicle of operational responsive space (ORS) was studied by using pseudospectral method. According to the characteristic of the trajectory design, the dynamics model was set up in the inertia right-angled reference frame, and the equation and parameter at the orbit injection point were simplified and converted. The infinite dimension dynamic optimal control problem was converted to a finite dimension static state optimization problem and the algorithm reduced the complexity so as to become a general algorithm in trajectories optimization. With the trajectories optimization of a three-stage solid vehicle with a liquor upper stage as example, the model of the trajectory optimization was set up and simulations were carried out. The results demonstrated the advantage and validity of the pseudospectral method. The rejection time of fairing was also analyzed by the simulation results, and the optimal flight procedure and trajectory were obtained.

  19. Determination of Optimal Control Strength of Delayed Feedback Control Using Time Series

    Institute of Scientific and Technical Information of China (English)

    YIN Hua-Wei; LU Wei-Ping; WANG Peng-Ye

    2004-01-01

    @@ We study controlling chaos using time-delayed feedback control based on chaotic time series without prior knowl edge of dynamical systems, and determine the optimal control parameters for stabilizing unstable periodic orbits with maximal stability.

  20. Wind power installations in Switzerland - Checklist for investors in large-scale installations; Windkraftanlagen in der Schweiz. Checkliste fuer Investoren von Grossanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Ott, W.; Kaufmann, Y.; Steiner, P. [Econcept AG, Zuerich (Switzerland); Gilgen, K.; Sartoris, A. [IRAP-HSR, Institut fuer Raumentwicklung an der Hochschule fuer Technik Rapperswil, Rapperswil (Switzerland)

    2008-07-01

    This report published by the Swiss Federal Office of Energy (SFOE) takes a look at a checklist for investors in large-scale wind-power installations. The authors state that the same questions are often posed in the course of the planning and realisation of wind turbine installations. This document presents a checklist that will help achieve the following goals: Tackling the steps involved in the planning and implementation phases, increasing planning security, systematic implementation in order to reduce risks for investors and to shorten time-scales as well as the reduction of costs. Further, participative processes can be optimised by using comprehensively prepared information in order to reduce the risk of objections during project approval. The structure of the check-list is described and discussed.

  1. Optimal paths planning in dynamic transportation networks with random link travel times

    Institute of Scientific and Technical Information of China (English)

    孙世超; 段征宇; 杨东援

    2014-01-01

    A theoretical study was conducted on finding optimal paths in transportation networks where link travel times were stochastic and time-dependent (STD). The methodology of relative robust optimization was applied as measures for comparing time-varying, random path travel times for a priori optimization. In accordance with the situation in real world, a stochastic consistent condition was provided for the STD networks and under this condition, a mathematical proof was given that the STD robust optimal path problem can be simplified into a minimum problem in specific time-dependent networks. A label setting algorithm was designed and tested to find travelers’ robust optimal path in a sampled STD network with computation complexity of O(n2+n·m). The validity of the robust approach and the designed algorithm were confirmed in the computational tests. Compared with conventional probability approach, the proposed approach is simple and efficient, and also has a good application prospect in navigation system.

  2. Response Time Optimization for Replica Selection Service in Data Grids

    Directory of Open Access Journals (Sweden)

    Husni H.E. AL-Mistarihi

    2008-01-01

    Full Text Available Problem Statement: Data Grid architecture provides a scalable infrastructure for grid services in order to manage data files and their corresponding replicas that were distributed across the globe. The grid services are designed to support a variety of data grid applications (jobs and projects. Replica selection is a high-level service that chooses a replica location from among many distributed replicas with the minimum response time for the users' jobs. Estimating the response time accurately in the grid environment is not an easy task. The current systems expose high response time in selecting the required replicas because the response time is estimated by considering the data transfer time only. Approach: We proposed a replica selection system that selects the best replica location for the users' running jobs in a minimum response time that can be estimated by considering new factors besides the data transfer time, namely, the storage access latency and the replica requests that waiting in the storage queue. Results: The performance of the proposed system was compared with a similar system that exists in the literature namely, SimpleOptimiser. The simulation results demonstrated that our system performed better than the SimpleOptimiser on an average of 6%. Conclusions: The proposed system can select the best replica location in a lesser response time than the SimpleOptimise. The efficiency of the proposed system is 6% higher than the SimpleOptimise. The efficiency level has a high impact on the quality of service that is perceived by grid users in a data grid environment where the data files are relatively big. For example, the data files produced from the scientific applications are of the size hundreds of Terabytes.

  3. Design of one-dimensional optical pulse-shaping filters by time-domain topology optimization

    DEFF Research Database (Denmark)

    Yang, Lirong; Lavrinenko, Andrei; Hvam, Jørn Märcher;

    2009-01-01

    Time-domain topology optimization is used here to design optical pulse-shaping filters in Si/SiO2 thin-film systems. A novel envelope objective function as well as explicit penalization are used to adapt the optimization method to this unique class of design problems.......Time-domain topology optimization is used here to design optical pulse-shaping filters in Si/SiO2 thin-film systems. A novel envelope objective function as well as explicit penalization are used to adapt the optimization method to this unique class of design problems....

  4. Scheduling with Optimized Communication for Time-Triggered Embedded Systems

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo

    1999-01-01

    We present an approach to process scheduling for synthesis of safety-critical distributed embedded systems.Our system model captures both the flow of data and that of control. The communication model is based on a time-triggered protocol. We take into consideration overheads due to communication...

  5. Optimization and Multiobjective Control of Time-Discrete Systems

    CERN Document Server

    Lozovanu, Dmitrii

    2009-01-01

    Presents developments and applications in the field of multiobjective control of time-discrete systems with a finite set of states. This work describes the dynamics of such systems by a directed graph in which each vertex corresponds to a dynamic state and the edges correspond to transitions of the system moving from one state to another.

  6. Optimizing a time-resolved X-ray absorption experiment

    CERN Document Server

    Bressler, C; Chergui, M; Abela, R; Pattison, P

    2001-01-01

    Calculations are presented of the optimum conditions for performing a laser-pump X-ray probe time-resolved X-ray absorption experiment. The results concerning sensitivity and feasibility for implementing the method are illustrated for the case of the nascent I radical environment following I sup - photolysis in H sub 2 O.

  7. Hypogeous fungi of Lithuania: a preliminary checklist

    Directory of Open Access Journals (Sweden)

    Ernestas Kutorga

    2013-12-01

    Full Text Available The paper reports on hypogeous fungi known from Lithuania, and data on their habitats, phenology, and distribution. References on the collections kept in the herbaria are also pointed out. The information is based on literature data and re-examination of all available voucher specimens. 22 species (12 genera, 3 phyla recorded from 124 localities are presented in a preliminary checklist.

  8. Hypogeous fungi of Lithuania: a preliminary checklist

    OpenAIRE

    Ernestas Kutorga; Marija Kataržytė

    2013-01-01

    The paper reports on hypogeous fungi known from Lithuania, and data on their habitats, phenology, and distribution. References on the collections kept in the herbaria are also pointed out. The information is based on literature data and re-examination of all available voucher specimens. 22 species (12 genera, 3 phyla) recorded from 124 localities are presented in a preliminary checklist.

  9. Pocket Checklists of Indonesian timber trees

    NARCIS (Netherlands)

    Prawira, Soewanda A.; Tantra, I.G.M.; Whitmore, T.C.

    1984-01-01

    Indonesia as yet does not have a comprehensive account of the forest trees which reach timber size (35 cm dbh = 14 inch or 105 cm gbh = 42 inch). A project has been started in August 1983 by the Botany Section of the Forest Research Institute in Bogor, Indonesia, to prepare pocket checklists of the

  10. Checklist of the marine bivalves from Peru

    Directory of Open Access Journals (Sweden)

    Carlos Paredes

    2016-08-01

    Full Text Available A checklist of the marine bivalve species from Peru is presented, this list has 401 species which are distributed in 65 families and 195 genera. The taxonomical classification and nomenclature is based on classical and current bibliography including Bernard (1983 and Coan & Valentich-Scott (2012. We give distribution and hábitat information about every species.

  11. Checklist energy efficient building in the flower bulbs sector; Checklist energiezuinig bouwen in de bloembollensector

    Energy Technology Data Exchange (ETDEWEB)

    Van Paridon, W.J.A.; Dol, J.J.

    2002-11-15

    This checklist shows the energy saving options for investments in buildings and installations for flower bulb businesses. Next to an energy efficiency improvement of 22%, the Long-term agreement for energy has also adopted the target of 4% sustainable energy deployment. This checklist therefore indicates for each category whether it is in the sustainable energy category or part of the regular saving options [Dutch] In deze checklist wordt aangegeven waar de mogelijkheden liggen tot besparing van energie bij investeringen in gebouwen en installaties voor bloembollenteeltbedrijven. In de meerjarenafspraak energie heeft de bloembollensector naast de energie efficiency verbetering van 22% ook de doelstelling opgenomen om 4% duurzame energie te gebruiken. In de checklist staat daarom per aspect of deze behoort tot de categorie duurzame energie of tot de normale besparingsopties.

  12. Optimization on temperature efficiency and switch time of thin-walled regenerator with perturbation analysis

    Institute of Scientific and Technical Information of China (English)

    AI Yuan-fang; MEI Chi; JIANG Shao-jian; HUANG Guo-dong; CHEN Hong-rong

    2006-01-01

    The heat transfer characteristic of honeycomb ceramic regenerator was optimized by the perturbation analytical-numerical method. The results show that there is a temperature efficiency peak and the corresponding optimal switch time. The decrease of air oxygen concentration leads to the decrease of maximum temperature efficiency. Optimal switch time is directly proportional to the matrix thickness. The solid heat conduction along the flow direction and the regenerator heat storage capacity of the unit volume have no impact on maximum temperature efficiency and optimal switch time. The temperature efficiency tendency based on the semi-analysis is the same as dispersion combustion tests with low oxygen concentration, and optimal switch time of 2 - 4 s agrees well with that of 4 s in high-temperature gasification tests. The possibility of design, operate and control a thin-walled regenerator with high efficiency by means of the perturbation method is proved.

  13. Optimal Perceived Timing: Integrating Sensory Information with Dynamically Updated Expectations.

    Science.gov (United States)

    Di Luca, Massimiliano; Rhodes, Darren

    2016-01-01

    The environment has a temporal structure, and knowing when a stimulus will appear translates into increased perceptual performance. Here we investigated how the human brain exploits temporal regularity in stimulus sequences for perception. We find that the timing of stimuli that occasionally deviate from a regularly paced sequence is perceptually distorted. Stimuli presented earlier than expected are perceptually delayed, whereas stimuli presented on time and later than expected are perceptually accelerated. This result suggests that the brain regularizes slightly deviant stimuli with an asymmetry that leads to the perceptual acceleration of expected stimuli. We present a Bayesian model for the combination of dynamically-updated expectations, in the form of a priori probability of encountering future stimuli, with incoming sensory information. The asymmetries in the results are accounted for by the asymmetries in the distributions involved in the computational process. PMID:27385184

  14. Optimizing the Time Performance of Subcontractors in Building Projects

    Directory of Open Access Journals (Sweden)

    Andy K.W Ng

    2010-07-01

    Full Text Available The main contractors of Hong Kong building projects tend to subcontract most of their work. However, many of the subcontractors complain that they are not being fully utilized due main contractors’ poor site coordination of temporary works and interfacing works and plant supports etc. A list of critical site coordination problems caused by main contractors that had adversely influence to the time performance of subcontractors was prepared. A questionnaire survey was conducted to collect data to generate multiple regression equations that explain how the critical site coordination problems affected the time performance of different types of subcontractor. The survey results were validated by neural network analysis. Backward elimination method was adopted to identify the ‘most critical’ site coordination problems that enable main contractors to formulate measures to enhance their site management system.

  15. Optimal Time-Reversed Wideband Signals for Distributed Sensing

    CERN Document Server

    Kim, Jerry; Mokole, Eric

    2015-01-01

    This paper considers a distributed wave-based sensing system that probes a scene consisting of multiple interacting idealized targets. Each sensor is a collocated transmit-receive pair that is capable of transmitting arbitrary wideband waveforms. We address the problem of finding the space-time transmit waveform that provides the best target detection performance in the sense of maximizing the energy scattered back into the receivers. Our approach is based on earlier work that constructed the solution by an iterative time-reversal (TR) process. In particular, for the case of idealized point-like scatterers in free space, we examine the frequency dependence of the eigenvalues of the TR operator, and we show that their behavior depends on constructive and destructive interference of the waves traveling along different paths. In addition, we show how these eigenvalues are connected to the poles of the Singularity Expansion Method. Our study of the frequency behavior distinguishes this work from most previous TR ...

  16. Optimizing the Time Performance of Subcontractors in Building Projects

    Directory of Open Access Journals (Sweden)

    Andy K.W Ng

    2010-07-01

    Full Text Available  The main contractors of Hong Kong building projects tend to subcontract most of their work. However, many of the subcontractors complain that they are not being fully utilized due main contractors’ poor site coordination of temporary works and interfacing works and plant supports etc. A list of critical site coordination problems caused by main contractors that had adversely influence to the time performance of subcontractors was prepared. A questionnaire survey was conducted to collect data to generate multiple regression equations that explain how the critical site coordination problems affected the time performance of different types of subcontractor. The survey results were validated by neural network analysis. Backward elimination method was adopted to identify the ‘most critical’ site coordination problems that enable main contractors to formulate measures to enhance their site management system.

  17. Optimal Perceived Timing: Integrating Sensory Information with Dynamically Updated Expectations

    Science.gov (United States)

    Di Luca, Massimiliano; Rhodes, Darren

    2016-01-01

    The environment has a temporal structure, and knowing when a stimulus will appear translates into increased perceptual performance. Here we investigated how the human brain exploits temporal regularity in stimulus sequences for perception. We find that the timing of stimuli that occasionally deviate from a regularly paced sequence is perceptually distorted. Stimuli presented earlier than expected are perceptually delayed, whereas stimuli presented on time and later than expected are perceptually accelerated. This result suggests that the brain regularizes slightly deviant stimuli with an asymmetry that leads to the perceptual acceleration of expected stimuli. We present a Bayesian model for the combination of dynamically-updated expectations, in the form of a priori probability of encountering future stimuli, with incoming sensory information. The asymmetries in the results are accounted for by the asymmetries in the distributions involved in the computational process. PMID:27385184

  18. Optimizing FPGA Design For Real Time Video Content Analysis

    OpenAIRE

    Ma, Xiaoyin

    2016-01-01

    The rapid growth of camera and storage capabilities, over the past decade, has resulted in an exponential growth in the size of video repositories, such as YouTube. In 2015, 400 hours of videos are uploaded to YouTube every minute. At the same time, massive amount of images/videos are generated from monitoring cameras for elderly, sick assistance, satellites for earth science research, and telescopes for space exploration. Human annotation and manual manipulation of such videos are infeasible...

  19. Optimal Control of Quasistatic Plasticity with Linear Kinematic Hardening Part I: Existence and Discretization in Time

    OpenAIRE

    Wachsmuth, Gerd

    2012-01-01

    In this paper we consider an optimal control problem governed by a time-dependent variational inequality arising in quasistatic plasticity with linear kinematic hardening. We address certain continuity properties of the forward operator, which imply the existence of an optimal control. Moreover, a discretization in time is derived and we show that every local minimizer of the continuous problem can be approximated by minimizers of modified, time-discrete problems.

  20. Stochastic optimal control and time changed Lévy noises

    OpenAIRE

    2014-01-01

    List of papers. Paper 1 / Chapter 2: On chaos representation and orthogonal polynomials for the doubly stochastic Poisson process, together with Giulia Di Nunno. Published in Seminar on stochastic analysis, random fields and applications VII, R. Daland, M. Dozzi and F. Russo (eds), vol 67 of Progress in Probability, Springer Basel 2013. doi:10.1007/978-3-0348-0545-2_2 The final publication is available at Springer. Paper 2 / Chapter 3: BSDEs for time-changed Lévy processes and applic...

  1. Uniform Hashing in Constant Time and Optimal Space

    DEFF Research Database (Denmark)

    Pagh, Anna Östlin; Pagh, Rasmus

    2008-01-01

    Many algorithms and data structures employing hashing have been analyzed under the uniform hashing assumption, i.e., the assumption that hash functions behave like truly random functions. Starting with the discovery of universal hash functions, many researchers have studied to what extent...... this theoretical ideal can be realized by hash functions that do not take up too much space and can be evaluated quickly. In this paper we present an almost ideal solution to this problem: a hash function $h: U\\rightarrow V$ that, on any set of $n$ inputs, behaves like a truly random function with high probability......, can be evaluated in constant time on a RAM and can be stored in $(1+\\epsilon)n\\log |V| + O(n+\\log\\log |U|)$ bits. Here $\\epsilon$ can be chosen to be any positive constant, so this essentially matches the entropy lower bound. For many hashing schemes this is the first hash function that makes...

  2. Study on application of safety checklist in preventive maintenance activities

    International Nuclear Information System (INIS)

    The paper describes the principles and the characteristics of safety checklist as a risk evaluation method. Examples of application of safety checklists to preventive maintenance activities such as criteria comparison and checkup items in place in nuclear power plants are illustrated in details with issues appeared in the checklist establishment. Checklist has a good application in the RCM analysis or in the actual preventive maintenance program for Chashma Nuclear Power Plant indicated by concrete instances. In the light of safety checklist which is used to sustain preventive maintenance as a simple and applicable risk analysis approach, we can get deep knowledge of risks of nuclear power plant to perfect preventive maintenance activities. (authors)

  3. Optimal control of nonlinear continuous-time systems in strict-feedback form.

    Science.gov (United States)

    Zargarzadeh, Hassan; Dierks, Travis; Jagannathan, Sarangapani

    2015-10-01

    This paper proposes a novel optimal tracking control scheme for nonlinear continuous-time systems in strict-feedback form with uncertain dynamics. The optimal tracking problem is transformed into an equivalent optimal regulation problem through a feedforward adaptive control input that is generated by modifying the standard backstepping technique. Subsequently, a neural network-based optimal control scheme is introduced to estimate the cost, or value function, over an infinite horizon for the resulting nonlinear continuous-time systems in affine form when the internal dynamics are unknown. The estimated cost function is then used to obtain the optimal feedback control input; therefore, the overall optimal control input for the nonlinear continuous-time system in strict-feedback form includes the feedforward plus the optimal feedback terms. It is shown that the estimated cost function minimizes the Hamilton-Jacobi-Bellman estimation error in a forward-in-time manner without using any value or policy iterations. Finally, optimal output feedback control is introduced through the design of a suitable observer. Lyapunov theory is utilized to show the overall stability of the proposed schemes without requiring an initial admissible controller. Simulation examples are provided to validate the theoretical results. PMID:26111400

  4. Free terminal time optimal control problem for the treatment of HIV infection

    Directory of Open Access Journals (Sweden)

    Amine Hamdache

    2016-01-01

    to provide the explicit formulations of the optimal controls. The corresponding optimality system with the additional transversality condition for the terminal time is derived and solved numerically using an adapted iterative method with a Runge-Kutta fourth order scheme and a gradient method routine.

  5. Hard and soft sub-time-optimal controllers for a mechanical system with uncertain mass

    DEFF Research Database (Denmark)

    Kulczycki, P.; Wisniewski, Rafal; Kowalski, P.;

    2004-01-01

    An essential limitation in using the classical optimal control has been its limited robustness to modeling inadequacies and perturbations. This paper presents conceptions of two practical control structures based on the time-optimal approach: hard and soft ones. The hard structure is defined by p...

  6. Sub-Finsler structures from the time-optimal control viewpoint for some nilpotent distributions

    OpenAIRE

    Barilari, Davide; Boscain, Ugo; Donne, Enrico Le; Sigalotti, Mario

    2015-01-01

    In this paper we study the sub-Finsler geometry as a time-optimal control problem. In particular, we consider non-smooth and non-strictly convex sub-Finsler structures associated with the Heisenberg, Grushin, and Martinet distributions. Motivated by problems in geometric group theory, we characterize extremal curves, discuss their optimality, and calculate the metric spheres, proving their Euclidean rectifiability.

  7. The optimal time path of clean energy R&D policy when patents have finite lifetime

    NARCIS (Netherlands)

    Gerlagh, R.; Kverndokk, S.; Rosendahl, K.E.

    2014-01-01

    We study the optimal time path for clean energy innovation policy. In a model with emission reduction through clean energy deployment, and with R&D increasing the overall productivity of clean energy, we describe optimal R&D policies jointly with emission pricing policies. We find that while emissio

  8. Stochastic multi-stage optimization at the crossroads between discrete time stochastic control and stochastic programming

    CERN Document Server

    Carpentier, Pierre; Cohen, Guy; De Lara, Michel

    2015-01-01

    The focus of the present volume is stochastic optimization of dynamical systems in discrete time where - by concentrating on the role of information regarding optimization problems - it discusses the related discretization issues. There is a growing need to tackle uncertainty in applications of optimization. For example the massive introduction of renewable energies in power systems challenges traditional ways to manage them. This book lays out basic and advanced tools to handle and numerically solve such problems and thereby is building a bridge between Stochastic Programming and Stochastic Control. It is intended for graduates readers and scholars in optimization or stochastic control, as well as engineers with a background in applied mathematics.

  9. Discrete-time neural inverse optimal control for nonlinear systems via passivation.

    Science.gov (United States)

    Ornelas-Tellez, Fernando; Sanchez, Edgar N; Loukianov, Alexander G

    2012-08-01

    This paper presents a discrete-time inverse optimal neural controller, which is constituted by combination of two techniques: 1) inverse optimal control to avoid solving the Hamilton-Jacobi-Bellman equation associated with nonlinear system optimal control and 2) on-line neural identification, using a recurrent neural network trained with an extended Kalman filter, in order to build a model of the assumed unknown nonlinear system. The inverse optimal controller is based on passivity theory. The applicability of the proposed approach is illustrated via simulations for an unstable nonlinear system and a planar robot. PMID:24807528

  10. Measurement properties and implementation of a checklist to assess leadership skills during interdisciplinary rounds in the intensive care unit.

    Science.gov (United States)

    Ten Have, Elsbeth C M; Nap, Raoul E; Tulleken, Jaap E

    2015-01-01

    The implementation of interdisciplinary teams in the intensive care unit (ICU) has focused attention on leadership behavior. A daily recurrent situation in ICUs in which both leadership behavior and interdisciplinary teamwork are integrated concerns the interdisciplinary rounds (IDRs). Although IDRs are recommended to provide optimal interdisciplinary and patient-centered care, there are no checklists available for leading physicians. We tested the measurement properties and implementation of a checklist to assess the quality of leadership skills in interdisciplinary rounds. The measurement properties of the checklist, which included 10 essential quality indicators, were tested for interrater reliability and internal consistency and by factor analysis. The interrater reliability among 3 raters was good (κ, 0.85) and the internal consistency was acceptable (α, 0.74). Factor analysis showed all factor loadings on 1 domain (>0.65). The checklist was further implemented during videotaped IDRs which were led by senior physicians and in which 99 patients were discussed. Implementation of the checklist showed a wide range of "no" and "yes" scores among the senior physicians. These results may underline the need for such a checklist to ensure tasks are synchronized within the team.

  11. Measurement Properties and Implementation of a Checklist to Assess Leadership Skills during Interdisciplinary Rounds in the Intensive Care Unit

    Directory of Open Access Journals (Sweden)

    Elsbeth C. M. Ten Have

    2015-01-01

    Full Text Available The implementation of interdisciplinary teams in the intensive care unit (ICU has focused attention on leadership behavior. A daily recurrent situation in ICUs in which both leadership behavior and interdisciplinary teamwork are integrated concerns the interdisciplinary rounds (IDRs. Although IDRs are recommended to provide optimal interdisciplinary and patient-centered care, there are no checklists available for leading physicians. We tested the measurement properties and implementation of a checklist to assess the quality of leadership skills in interdisciplinary rounds. The measurement properties of the checklist, which included 10 essential quality indicators, were tested for interrater reliability and internal consistency and by factor analysis. The interrater reliability among 3 raters was good (κ, 0.85 and the internal consistency was acceptable (α, 0.74. Factor analysis showed all factor loadings on 1 domain (>0.65. The checklist was further implemented during videotaped IDRs which were led by senior physicians and in which 99 patients were discussed. Implementation of the checklist showed a wide range of “no” and “yes” scores among the senior physicians. These results may underline the need for such a checklist to ensure tasks are synchronized within the team.

  12. Deterministic Time-inconsistent Optimal Control Problems - an Essentially Cooperative Approach

    Institute of Scientific and Technical Information of China (English)

    Jiong-min YONG

    2012-01-01

    A general deterministic time-inconsistent optimal control problem is formulated for ordinary differential equations.To find a time-consistent equilibrium value function and the corresponding time-consistent equilibrium control,a non-cooperative N-person differential game (but essentially cooperative in some sense) is introduced.Under certain conditions,it is proved that the open-loop Nash equilibrium value function of the N-person differential game converges to a time-consistent equilibrium value function of the original problem,which is the value function of a time-consistent optimal control problem.Moreover,it is proved that any optimal control of the time-consistent limit problem is a time-consistent equilibrium control of the original problem.

  13. An Independent Human Factors Analysis and Evaluation of the Emergency Medical Protocol Checklist for the International Space Station

    Science.gov (United States)

    Marshburn, Thomas; Whitmore, Mihriban; Ortiz, Rosie; Segal, Michele; Smart, Kieran; Hughes, Catherine

    2003-01-01

    Emergency medical capabilities aboard the ISS include a Crew Medical Officer (CMO) (not necessarily a physician), and back-up, resuscitation equipment, and a medical checklist. It is essential that CMOs have reliable, usable and informative medical protocols that can be carried out independently in flight. The study evaluates the existing ISS Medical Checklist layout against a checklist updated to reflect a human factors approach to structure and organization. Method: The ISS Medical checklist was divided into non-emergency and emergency sections, and re-organized based on alphabetical and a body systems approach. A desk-top evaluation examined the ability of subjects to navigate to specific medical problems identified as representative of likely non-emergency events. A second evaluation aims to focus on the emergency section of the Medical Checklist, based on the preliminary findings of the first. The final evaluation will use Astronaut CMOs as subjects comparing the original checklist against the updated layout in the task of caring for a "downed crewmember" using a Human Patient Simulator [Medical Education Technologies, Inc.]. Results: Initial results have demonstrated a clear improvement of the re-organized sections to determine the solution to the medical problems. There was no distinct advantage for either alternative, although subjects stated having a preference for the body systems approach. In the second evaluation, subjects will be asked to identify emergency medical conditions, with measures including correct diagnosis, time to completion and solution strategy. The third evaluation will compare the original and fully updated checklists in clinical situations. Conclusions: Initial findings indicate that the ISS Medical Checklist will benefit from a reorganization. The present structure of the checklist has evolved over recent years without systematic testing of crewmember ability to diagnose medical problems. The improvements are expected to enable ISS

  14. Optimal pricing strategies for capacity leasing based on time and volume usage in telecommunication networks

    OpenAIRE

    Kasap, Nihat; Tektaş Sivrikaya, Berna; Tektas Sivrikaya, Berna; Delen, Dursun

    2013-01-01

    In this study, we use a monopoly pricing model to examine the optimal pricing strategies for “pay-per-time”, “pay-per-volume” and “pay-per both time and volume” based leasing of data networks. Traditionally, network capacity distribution includes short/long term bandwidth and/or usage time leasing. Each consumer has a choice to select volume based, connection-time based or both volume and connection-time based pricing. When customers choose connection-time based pricing, their optimal behavio...

  15. Time Reversal Reconstruction Algorithm Based on PSO Optimized SVM Interpolation for Photoacoustic Imaging

    Directory of Open Access Journals (Sweden)

    Mingjian Sun

    2015-01-01

    Full Text Available Photoacoustic imaging is an innovative imaging technique to image biomedical tissues. The time reversal reconstruction algorithm in which a numerical model of the acoustic forward problem is run backwards in time is widely used. In the paper, a time reversal reconstruction algorithm based on particle swarm optimization (PSO optimized support vector machine (SVM interpolation method is proposed for photoacoustics imaging. Numerical results show that the reconstructed images of the proposed algorithm are more accurate than those of the nearest neighbor interpolation, linear interpolation, and cubic convolution interpolation based time reversal algorithm, which can provide higher imaging quality by using significantly fewer measurement positions or scanning times.

  16. Optimal timing of coronary invasive strategy in non-ST-segment elevation acute coronary syndromes

    DEFF Research Database (Denmark)

    Navarese, Eliano P; Gurbel, Paul A; Andreotti, Felicita;

    2013-01-01

    The optimal timing of coronary intervention in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACSs) is a matter of debate. Conflicting results among published studies partly relate to different risk profiles of the studied populations....

  17. Checklist of the Diptera (Insecta of Finland: an introduction and a summary of results

    Directory of Open Access Journals (Sweden)

    Jere Kahanpää

    2014-09-01

    Full Text Available Nearly thirty-five years have passed since Hackman published his “Check list of the Finnish Diptera” (1980. The number of true flies (Diptera known from Finland has increased by more than two thousand species since then. At the same time, hundreds of erroneous records have been recognized and purged from the checklist. ZooKeys issue 441 provides a new checklist of the Diptera species of the Republic of Finland. This introductory paper presents the rationale behind the project, provides technical documentation on the checklist format and sources used, and summarizes the results. The remaining papers in this issue cover one or more Diptera families in detail. Two electronic appendices are provided: supporting data (additional references to first published records and the previous checklist and a complete list of Finnish Diptera taxa in Darwin Core compliant format for easy computer access and processing. The new checklist records 6920 fly species from Finland, 2932 belonging to the nematoceran or lower flies and 3989 to the suborder Brachycera. The changes since 1980 are most prominent in the Lower Diptera. For example, more than 400 non-biting midges (Chironomidae have been added since 1980, and the number of moth flies (Psychodidae known from Finland has more than tripled. Among the larger families, large increases in known Finnish species are also seen in Cecidomyiidae (161% increase, Pipunculidae (98%, and Chironomidae (90%.

  18. Worst-Case Execution Time Based Optimization of Real-Time Java Programs

    DEFF Research Database (Denmark)

    Hepp, Stefan; Schoeberl, Martin

    2012-01-01

    optimization is method in lining. It is especially important for languages, like Java, where small setter and getter methods are considered good programming style. In this paper we present and explore WCET driven in lining of Java methods. We use the WCET analysis tool for the Java processor JOP to guide...

  19. Optimal scan time for evaluation of parathyroid adenoma with [18F]-fluorocholine PET/CT

    Directory of Open Access Journals (Sweden)

    Rep Sebastijan

    2015-12-01

    Full Text Available Background. Parathyroid adenomas, the most common cause of primary hyperparathyroidism, are benign tumours which autonomously produce and secrete parathyroid hormone. [18F]-fluorocholine (FCH, PET marker of cellular proliferation, was recently demonstrated to accumulate in lesions representing enlarged parathyroid tissue; however, the optimal time to perform FCH PET/CT after FCH administration is not known. The aim of this study was to determine the optimal scan time of FCH PET/CT in patients with primary hyperparathyroidism.

  20. The generalised continuous algebraic Riccati equation and impulse-free continuous-time LQ optimal control

    OpenAIRE

    Ferrante, Augusto; Ntogramatzidis, Lorenzo

    2013-01-01

    The purpose of this paper is to investigate the role that the continuous-time generalised Riccati equation plays within the context of singular linear-quadratic optimal control. This equation has been defined following the analogy with the discrete-time generalised Riccati equation, but, differently from the discrete case, to date the importance of this equation in the context of optimal control is yet to be understood. This note addresses this point. We show in particular that when the conti...

  1. OPTIMIZING TIME WINDOWS FOR MANAGING ARRIVALS OF EXPORT CONTAINERS AT CHINESE CONTAINER TERMINALS

    DEFF Research Database (Denmark)

    Chen, Gang; Yang, Zhongzhen

    2009-01-01

      Managing the truck transport in a port area is important for Chinese container ports as heavy traffic congestion not only limits the terminal capacity but also generates serious air pollution. This paper explores an effective way to manage the truck traffic of export containers based on a time...... of driver and truck waiting time, the cost of container cargo storage time, the truck idle cost and terminal yard fee. Secondly, to minimize the costs, a heuristic is developed based on a genetic algorithm to optimize the time window arrangement. The optimal solution involves the position and the length...... of each time window. Finally, the heuristic is applied to a Chinese container terminal, and the result indicates that the optimization of time windows can successfully flatten the peak of truck traffic of export containers, which is the primary reason of road traffic congestion in port areas....

  2. Real-time inverse high-dose-rate brachytherapy planning with catheter optimization by compressed sensing-inspired optimization strategies

    Science.gov (United States)

    Guthier, C. V.; Aschenbrenner, K. P.; Müller, R.; Polster, L.; Cormack, R. A.; Hesser, J. W.

    2016-08-01

    This paper demonstrates that optimization strategies derived from the field of compressed sensing (CS) improve computational performance in inverse treatment planning (ITP) for high-dose-rate (HDR) brachytherapy. Following an approach applied to low-dose-rate brachytherapy, we developed a reformulation of the ITP problem with the same mathematical structure as standard CS problems. Two greedy methods, derived from hard thresholding and subspace pursuit are presented and their performance is compared to state-of-the-art ITP solvers. Applied to clinical prostate brachytherapy plans speed-up by a factor of 56-350 compared to state-of-the-art methods. Based on a Wilcoxon signed rank-test the novel method statistically significantly decreases the final objective function value (p  <  0.01). The optimization times were below one second and thus planing can be considered as real-time capable. The novel CS inspired strategy enables real-time ITP for HDR brachytherapy including catheter optimization. The generated plans are either clinically equivalent or show a better performance with respect to dosimetric measures.

  3. Checklist of the marine macroalgae of Vietnam

    OpenAIRE

    Nguyen, T.V.; Le, H.N.; Lin, S. M.; Steen, F. van der; De Clerck, O.

    2013-01-01

    Despite a rich seaweed flora, information about Vietnamese seaweeds is scattered throughout a large number of often regional publications and, hence, difficult to access. This paper presents an up-to-date checklist of the marine macroalgae of Vietnam, compiled by means of an exhaustive bibliographical search and revision of taxon names. A total of 827 species are reported, of which the Rhodophyta show the highest species number (412 species), followed by the Chlorophyta (180 species), Phaeoph...

  4. Pocket Checklists of Indonesian timber trees

    OpenAIRE

    Prawira, Soewanda A.; Tantra, I.G.M.; Whitmore, T.C.

    1984-01-01

    Indonesia as yet does not have a comprehensive account of the forest trees which reach timber size (35 cm dbh = 14 inch or 105 cm gbh = 42 inch). A project has been started in August 1983 by the Botany Section of the Forest Research Institute in Bogor, Indonesia, to prepare pocket checklists of the timber trees of all regions of the country. These lists will include forest-based descriptions, keys and line drawings.

  5. Time-optimal trajectories for mobile robots with two independently driven wheels

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.; Pin, F.G. (Oak Ridge National Lab., TN (United States))

    1994-02-01

    This article addresses the problem of time-optimal motions for a mobile platform in a planar environment. The platform has two nonsteerable, independently driven wheels. The overall mission of the robot is expressed in terms of a sequence of via points at which the platform must be at rest in a given configuration (position and orientation). The objective is to plan time-optimal trajectories between these configurations, assuming an unobstructed environment. Using Pontryagin's maximum principle (PMP), we formally demonstrate that all time-optimal motions of the platform for this problem occur for bang-bang controls on the wheels (at each instant, the acceleration on each wheel is at either its upper or its lower limit). The PMP, however, provides only the conditions necessary for time optimality. To find the time-optimal robot trajectories, we first parameterize the bang-bang trajectories using the switch times on the wheels (the times at which the wheel accelerations change sign). With this parameterization, we can fully search the robot trajectory space and find the switch times that will produce particular paths to a desired final configuration of the platform. We show numerically that robot trajectories with three switch times (two on one wheel and one on the other) can reach any position, while trajectories with four switch times can reach any configuration. By numerical comparison with other trajectories involving similar or greater numbers of switch times, we then identify the sets of time-optimal trajectories. 28 refs., 22 figs., 1 tab.

  6. Methodology to Optimize Manufacturing Time for a CNC Using a High Performance Implementation of ACO

    Directory of Open Access Journals (Sweden)

    Oscar Montiel-Ross

    2012-10-01

    Full Text Available In this paper, an efficient methodology to generate optimal and/or quasi‐optimal sequences of G commands to minimize the manufacturing time is presented. Our solution starts from original G codes provided by application CAD/CAM software. Here, first we tackled the problem of reducing the time of the travel path for drilling of an industrial robotic manufacturing machine. The methodology can be easily implemented for free distribution or commercial CAD/CAM software without achieving any modification to it. Several experiments that demonstrate how this proposal can help to outperform solutions provided by application software are presented, consistent improvements around 62% were obtained. Moreover, for optimizing the time along the travel path, we present a high performance implementation of Ant Colonies (ACO known as Parallel ACO (P‐ACO that allows achieving the optimization task efficiently by speeding up the original ACO. A Graphical User Interface that integrates the whole process is shown.

  7. Real-time optimization power-split strategy for hybrid electric vehicles

    Institute of Scientific and Technical Information of China (English)

    XIA ChaoYing; ZHANG Cong

    2016-01-01

    Energy management strategies based on optimal control theory can achieve minimum fuel consumption for hybrid electric vehicles,but the requirement for driving cycles known in prior leads to a real-time problem.A real-time optimization power-split strategy is proposed based on linear quadratic optimal control.The battery state of charge sustainability and fuel economy are ensured by designing a quadratic performance index combined with two rules.The engine power and motor power of this strategy are calculated in real-time based on current system state and command,and not related to future driving conditions.The simulation results in ADVISOR demonstrate that,under the conditions of various driving cycles,road slopes and vehicle parameters,the proposed strategy significantly improves fuel economy,which is very close to that of the optimal control based on Pontryagin's minimum principle,and greatly reduces computation complexity.

  8. Planning the Minimum Time and Optimal Survey Trajectory for Autonomous Underwater Vehicles in Uncertain Current

    Directory of Open Access Journals (Sweden)

    Michael A. Hurni

    2015-12-01

    Full Text Available The authors develop an approach to a “best” time path for Autonomous Underwater Vehicles conducting oceanographic measurements under uncertain current flows. The numerical optimization tool DIDO is used to compute hybrid minimum time and optimal survey paths for a sample of currents between ebb and flow. A simulated meta-experiment is performed where the vehicle traverses the resulting paths under different current strengths per run. The fastest elapsed time emerges from a payoff table. A multi-objective function is then used to weigh the time to complete a mission versus measurement inaccuracy due to deviation from the desired survey path.

  9. Optimal design of systems that evolve over time using neural networks

    Science.gov (United States)

    Nolan, Michael K.

    2007-04-01

    Design optimization is challenging when the number of variables becomes large. One method of addressing this problem is to use pattern recognition to decrease the solution space in which the optimizer searches. Human "common sense" is used by designers to narrow the scope of search to a confined area defined by patterns conforming to likely solution candidates. However, computer-based optimization generally does not apply similar heuristics. In this paper, a system is presented that recognizes patterns and adjusts its search for optimal solutions based on these patterns. A design problem was selected that requires the optimization algorithm to assess designs that evolve over time. A small sensor network design is evolved into a larger sensor network design. Optimal design solutions for the small network do not necessarily lead to optimal solutions for the larger network. Systems that are well-positioned to evolve have characteristics that distinguish themselves from systems that are not well-positioned to evolve. In this study, a neural network was able to recognize a pattern whereby flexible sensor networks evolved more successfully than less flexible networks. The optimizing algorithm used this pattern to select candidate systems that showed promise for evolution. A genetic algorithm assisted by a neural network achieved better performance than an unassisted genetic algorithm did. This thesis advocates the merit of neural network use in multi-objective system design optimization and to lay a basis for future study.

  10. Time optimal trajectories for mobile robots with two independently driven wheels

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.; Pin, F.G.

    1992-03-01

    This paper addresses the problem of time-optional motions for a mobile platform in a planar environment. The platform has two non-steerable independently driven wheels. The overall mission of the robot is expressed in terms of a sequence of via points at which the platform must be at rest in a given configuration (position and orientation). The objective is to plan time-optimal trajectories between these configurations assuming an unobstructed environment. Using Pontryagin's maximum principle (PMP), we formally demonstrate that all time optimal motions of the platform for this problem occur for bang-bang controls on the wheels (at each instant, the acceleration on each wheel is either at its upper or lower limit). The PMP, however, only provides necessary conditions for time optimality. To find the time optimal robot trajectories, we first parameterize the bang-bang trajectories using the switch times on the wheels (the times at which the wheel accelerations change sign). With this parameterization, we can fully search the robot trajectory space and find the switch times that will produce particular paths to a desired final configuration of the platform. We show numerically that robot trajectories with three switch times (two on one wheel, one on the other) can reach any position, while trajectories with four switch times can reach any configuration. By numerical comparison with other trajectories involving similar or greater numbers of switch times, we then identify the sets of time-optimal trajectories. These are uniquely defined using ranges of the parameters, and consist of subsets of trajectories with three switch times for the problem when the final orientation of the robot is not specified, and four switch times when a full final configuration is specified. We conclude with a description of the use of the method for trajectory planning for one of our robots.

  11. Time optimal trajectories for mobile robots with two independently driven wheels

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.; Pin, F.G.

    1992-03-01

    This paper addresses the problem of time-optional motions for a mobile platform in a planar environment. The platform has two non-steerable independently driven wheels. The overall mission of the robot is expressed in terms of a sequence of via points at which the platform must be at rest in a given configuration (position and orientation). The objective is to plan time-optimal trajectories between these configurations assuming an unobstructed environment. Using Pontryagin`s maximum principle (PMP), we formally demonstrate that all time optimal motions of the platform for this problem occur for bang-bang controls on the wheels (at each instant, the acceleration on each wheel is either at its upper or lower limit). The PMP, however, only provides necessary conditions for time optimality. To find the time optimal robot trajectories, we first parameterize the bang-bang trajectories using the switch times on the wheels (the times at which the wheel accelerations change sign). With this parameterization, we can fully search the robot trajectory space and find the switch times that will produce particular paths to a desired final configuration of the platform. We show numerically that robot trajectories with three switch times (two on one wheel, one on the other) can reach any position, while trajectories with four switch times can reach any configuration. By numerical comparison with other trajectories involving similar or greater numbers of switch times, we then identify the sets of time-optimal trajectories. These are uniquely defined using ranges of the parameters, and consist of subsets of trajectories with three switch times for the problem when the final orientation of the robot is not specified, and four switch times when a full final configuration is specified. We conclude with a description of the use of the method for trajectory planning for one of our robots.

  12. Two neural network algorithms for designing optimal terminal controllers with open final time

    Science.gov (United States)

    Plumer, Edward S.

    1992-01-01

    Multilayer neural networks, trained by the backpropagation through time algorithm (BPTT), have been used successfully as state-feedback controllers for nonlinear terminal control problems. Current BPTT techniques, however, are not able to deal systematically with open final-time situations such as minimum-time problems. Two approaches which extend BPTT to open final-time problems are presented. In the first, a neural network learns a mapping from initial-state to time-to-go. In the second, the optimal number of steps for each trial run is found using a line-search. Both methods are derived using Lagrange multiplier techniques. This theoretical framework is used to demonstrate that the derived algorithms are direct extensions of forward/backward sweep methods used in N-stage optimal control. The two algorithms are tested on a Zermelo problem and the resulting trajectories compare favorably to optimal control results.

  13. An Optimization Method of Time Window Based on Travel Time and Reliability

    OpenAIRE

    Fengjie Fu; Dongfang Ma; Dianhai Wang; Wei Qian

    2015-01-01

    The dynamic change of urban road travel time was analyzed using video image detector data, and it showed cyclic variation, so the signal cycle length at the upstream intersection was conducted as the basic unit of time window; there was some evidence of bimodality in the actual travel time distributions; therefore, the fitting parameters of the travel time bimodal distribution were estimated using the EM algorithm. Then the weighted average value of the two means was indicated as the travel t...

  14. The Impact of Mutation Rate on the Computation Time of Evolutionary Dynamic Optimization

    CERN Document Server

    Chen, Tianshi; Tang, Ke; Chen, Guoliang; Yao, Xin

    2011-01-01

    Mutation has traditionally been regarded as an important operator in evolutionary algorithms. In particular, there have been many experimental studies which showed the effectiveness of adapting mutation rates for various static optimization problems. Given the perceived effectiveness of adaptive and self-adaptive mutation for static optimization problems, there have been speculations that adaptive and self-adaptive mutation can benefit dynamic optimization problems even more since adaptation and self-adaptation are capable of following a dynamic environment. However, few theoretical results are available in analyzing rigorously evolutionary algorithms for dynamic optimization problems. It is unclear when adaptive and self-adaptive mutation rates are likely to be useful for evolutionary algorithms in solving dynamic optimization problems. This paper provides the first rigorous analysis of adaptive mutation and its impact on the computation times of evolutionary algorithms in solving certain dynamic optimizatio...

  15. Optimal guaranteed cost control for fuzzy descriptor systems with time-varying delay

    Institute of Scientific and Technical Information of China (English)

    Tian Weihua; Zhang Huaguang

    2008-01-01

    Based on the delay-independent rule, the problem of optimal guaranteed cost control for a class of Takagi-Sugeno (T-S) fuzzy descriptor systems with time-varying delay is studied. A linear quadratic cost function is considered as the performance index of the closed-loop system. Sufficient conditions for the existence of guaranteed cost controllers via state feedback are given in terms of linear matrix inequalities (LMIs), and the design of an optimal guaranteed cost controller can be reduced to a convex optimization problem. It is shown that the designed controller not only guarantees the asymptotic stability of the closed-loop fuzzy descriptor delay system, but also provides an optimized upper bound of the guaranteed cost. At last, a numerical example is given to illustrate the effectiveness of the proposed method and the perfect performance of the optimal guaranteed cost controller.

  16. Dynamic modeling and optimization for space logistics using time-expanded networks

    Science.gov (United States)

    Ho, Koki; de Weck, Olivier L.; Hoffman, Jeffrey A.; Shishko, Robert

    2014-12-01

    This research develops a dynamic logistics network formulation for lifecycle optimization of mission sequences as a system-level integrated method to find an optimal combination of technologies to be used at each stage of the campaign. This formulation can find the optimal transportation architecture considering its technology trades over time. The proposed methodologies are inspired by the ground logistics analysis techniques based on linear programming network optimization. Particularly, the time-expanded network and its extension are developed for dynamic space logistics network optimization trading the quality of the solution with the computational load. In this paper, the methodologies are applied to a human Mars exploration architecture design problem. The results reveal multiple dynamic system-level trades over time and give recommendation of the optimal strategy for the human Mars exploration architecture. The considered trades include those between In-Situ Resource Utilization (ISRU) and propulsion technologies as well as the orbit and depot location selections over time. This research serves as a precursor for eventual permanent settlement and colonization of other planets by humans and us becoming a multi-planet species.

  17. 3D Pattern Synthesis of Time-Modulated Conformal Arrays with a Multiobjective Optimization Approach

    Directory of Open Access Journals (Sweden)

    Wentao Li

    2014-01-01

    Full Text Available This paper addresses the synthesis of the three-dimensional (3D radiation patterns of the time-modulated conformal arrays. Due to the nature of periodic time modulation, harmonic radiation patterns are generated at the multiples of the modulation frequency in time-modulated arrays. Thus, the optimization goal of the time-modulated conformal array includes the optimization of the sidelobe level at the operating frequency and the sideband levels (SBLs at the harmonic frequency, and the design can be regarded as a multiobjective problem. The multiobjective particle swarm optimization (MOPSO is applied to optimize the switch-on instants and pulse durations of the time-modulated conformal array. To significantly reduce the optimization variables, the modified Bernstein polynomial is employed in the synthesis process. Furthermore, dual polarized patch antenna is designed as radiator to achieve low cross-polarization level during the beam scanning. A 12 × 13 (156-element conical conformal microstrip array is simulated to demonstrate the proposed synthesis mechanism, and good results reveal the promising ability of the proposed algorithm in solving the synthesis of the time-modulated conformal arrays problem.

  18. Nuclear Power Plant Construction Scheduling Problem with Time Restrictions: A Particle Swarm Optimization Approach

    Directory of Open Access Journals (Sweden)

    Shang-Kuan Chen

    2016-01-01

    Full Text Available In nuclear power plant construction scheduling, a project is generally defined by its dependent preparation time, the time required for construction, and its reactor installation time. The issues of multiple construction teams and multiple reactor installation teams are considered. In this paper, a hierarchical particle swarm optimization algorithm is proposed to solve the nuclear power plant construction scheduling problem and minimize the occurrence of projects failing to achieve deliverables within applicable due times and deadlines.

  19. Ant colony optimization applied to route planning using link travel time predictions

    OpenAIRE

    Claes, Rutger; Holvoet, Tom

    2011-01-01

    Finding the shortest path in a road network is a well known problem. Various proven static algorithms such as Dijkstra and A* are extensively evaluated and implemented. When confronted with dynamic costs, such as link travel time predictions, alternative route planning algorithms have to be applied. This paper applies Ant Colony Optimization combined with link travel time predictions to find routes that reduce the time spend by travels by taking into account link travel time predictions. The ...

  20. Checklist of the Quill mites (Acariformes: Syringophilidae) of the World.

    Science.gov (United States)

    Glowska, Eliza; Chrzanowski, Mateusz; Kaszewska, Katarzyna

    2015-01-01

    Mites of the family Syringophilidae (Acariformes: Cheyletoidea) are ectoparasites inhabiting the quills of various feather types in many groups of birds. Until now, 334 valid species and 60 genera of quill mites have been described and recorded from 482 bird species (95 families and 24 orders). Currently, the family is divided into 2 subfamilies: Syringophilinae Lavoipierre, 1953 with 260 species grouped in 49 genera, and Picobinae Johnston and Kethley, 1973 with 74 species grouped in 11 genera. Mites of the subfamily Syringophilinae inhabit quills of primaries, secondaries, tertials, rectrices and wing coverts and just occasionally the body feathers; representatives of the subfamily Picobinae live predominantly inside the body feathers. The rapid increase of the knowledge on biodiversity and systematics of quill mites started in end of the 1990s; numerous new descriptions appeared since that time and taxonomic rearrangements make an urgent need to summarize all previous data. We present a complete checklist of the family Syringophilidae of the world including the following data: a species name, author(s), references, a number of first page of description, figure numbers in descriptions, depository of type and non-type materials, host spectrum and geographical distribution. The checklist is additionally provided with the table including bird hosts and associated quill mite species. PMID:26249476

  1. Geometric optimal design of MR damper considering damping force, control energy and time constant

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Q H; Choi, S B [Smart Structures and Systems Laboratory, Department of Mechanical Engineering, INHA University, Incheon 402-751 (Korea, Republic of); Kim, K S [Department of Mechanical and Automotive Engineering, Kongju National University, Chonan 330-240 (Korea, Republic of)], E-mail: seungbok@inha.ac.kr

    2009-02-01

    This paper presents an optimal design of magnetorheological (MR) damper based on finite element analysis. The MR damper is constrained in a specific volume and the optimization problem identifies geometric dimensions of the damper that minimizes an objective function. The objective function is proposed by considering the damping force, dynamic range and the inductive time constant of the damper. After describing the configuration of the MR damper, a quasi-static modelling of the damper is performed based on Bingham model of MR fluid. The initial geometric dimensions of the damper are then determined based on the assumption of constant magnetic flux density throughout the magnetic circuit of the damper. Subsequently, the optimal design variables that minimize the objective function are determined using a golden-section algorithm and a local quadratic fitting technique via commercial finite element method parametric design language. A comparative work on damping force and time constant between the initial and optimal design is undertaken.

  2. Time-explicit methods for joint economical and geological risk mitigation in production optimization

    DEFF Research Database (Denmark)

    Christiansen, Lasse Hjuler; Capolei, Andrea; Jørgensen, John Bagterp

    2016-01-01

    Real-life applications of production optimization face challenges of risks related to unpredictable fluctuations in oil prices and sparse geological data. Consequently, operating companies are reluctant to adopt model-based production optimization into their operations. Conventional production...... therefore leave the oil production subject to substantial economical risk. To address this challenge, this paper introduces a novel set of time-explicit (TE) methods, which combine ideas of multi-objective optimization and ensemble-based risk mitigation into a computationally tractable joint effort...... of mitigating economical and geological risks. As opposed to conventional strategies that focus on a single long-term objective, TE methods seek to reduce risks and promote returns over the entire reservoir life by optimization of a given ensemble-based geological risk measure over time. By explicit involvement...

  3. Genetic Algorithm for Mulicriteria Optimization of a Multi-Pickup and Delivery Problem with Time Windows

    CERN Document Server

    Dridi, Imen Harbaoui; Ksouri, Mekki; Borne, Pierre

    2010-01-01

    In This paper we present a genetic algorithm for mulicriteria optimization of a multipickup and delivery problem with time windows (m-PDPTW). The m-PDPTW is an optimization vehicles routing problem which must meet requests for transport between suppliers and customers satisfying precedence, capacity and time constraints. This paper purposes a brief literature review of the PDPTW, present an approach based on genetic algorithms and Pareto dominance method to give a set of satisfying solutions to the m-PDPTW minimizing total travel cost, total tardiness time and the vehicles number.

  4. Annotated checklist of the mosquito species encountered during arboviral studies in Iquitos, Peru (Diptera: Culicidae).

    Science.gov (United States)

    Pecor, J E; Jones, J; Turell, M J; Fernandez, R; Carbajal, F; O'Guinn, M; Sardalis, M; Watts, D; Zyzak, M; Calampa, C; Klein, T A

    2000-09-01

    A checklist of the mosquito fauna encountered during arboviral studies in Iquitos, Peru, is presented. A total of 16 genera, 30 subgenera, and 96 species were identified, including 24 species reported from Peru for the 1st time. Notations on the taxonomy and biology for 28 species are also provided.

  5. A Uniaxial Optimal Perfectly Matched Layer Method for Time-harmonic Scattering Problems

    Institute of Scientific and Technical Information of China (English)

    YANG XIAO-YING; MA FU-MING; ZHANG DE-YUE; DU XIN-WEI

    2010-01-01

    We develop a uniaxial optimal perfectly matched layer (opt PML) method for solving the time-harmonic scattering problems by choosing a particular absorbing function with unbounded integral in a rectangular domain. With this choice, the solution of the optimal PML problem not only converges exponentially to the solution of the original scatting problem, but also is insensitive to the thickness of the PML layer for sufficiently small parameter e0. Numerical experiments are included to illustrate the competitive behavior of the proposed optimal method.

  6. Fast reactor parameter optimization taking into account changes in fuel charge type during reactor operation time

    International Nuclear Information System (INIS)

    The formulation and solution of optimization problem for parameters determining the layout of the central part of sodium cooled power reactor taking into account possible changes in fuel charge type during reactor operation time are performed. The losses under change of fuel composition type for two reactor modifications providing for minimum doubling time for oxide and carbide fuels respectively, are estimated

  7. Necessary optimality conditions for the calculus of variations on time scales

    OpenAIRE

    Ferreira, Rui A. C.; Torres, Delfim F. M.

    2007-01-01

    We study more general variational problems on time scales. Previous results are generalized by proving necessary optimality conditions for (i) variational problems involving delta derivatives of more than the first order, and (ii) problems of the calculus of variations with delta-differential side conditions (Lagrange problem of the calculus of variations on time scales).

  8. Optimal Timing of Carbon Capture Policies Under Alternative CCS Cost Functions

    OpenAIRE

    Amigues, Jean-Pierre; Lafforgue, Gilles; MOREAUX Michel

    2012-01-01

    We determine the optimal exploitation time-paths of three types of perfect substitute energy resources: The first one is depletable and carbon-emitting (dirty coal), the second one is also depletable but carbon-free thanks to a carbon capture and storage (CCS) process (clean coal) and the last one is renewable and clean (solar energy). We assume that the atmospheric carbon stock cannot exceed some given ceiling. These optimal paths are considered along with alternative structures of the CCS c...

  9. The Effects of Task Structure on Time-sharing Efficiency and Resource Allocation Optimality

    Science.gov (United States)

    Tsang, P. S.; Wickens, C. D.

    1984-01-01

    A distinction was made between two aspects of time sharing performance: time sharing efficiency and attention allocation optimality. A secondary task technique was employed to evaluate the effects of the task structures of the component time shared tasks on both aspects of the time sharing performance. Five pairs of dual tasks differing in their structural configurations were investigated. The primary task was a visual/manual tracking task which requires spatial processing. The secondary task was either another tracking task or a verbal memory task with one of four different input/output configurations. Congruent to a common finding, time-sharing efficiency was observed to decrease with an increasing overlap of resources utilized by the time shared tasks. Research also tends to support the hypothesis that resource allocation is more optimal when the time shared tasks placed heavy demands on common processing resources than when they utilized separate resources.

  10. Real-time spatial optimization : based on the application in wood supply chain management

    International Nuclear Information System (INIS)

    Real-time spatial optimization - a combination of Geographical Information Science and Technology and Operations Research - is capable of generating optimized solutions to given spatial problems in real-time. The basic concepts to develop a real-time spatial optimization system are outlined in this thesis. Geographic Information Science delivers the foundations for acquiring, storing, manipulating, visualizing and analyzing spatial information. In order to develop a system that consists of several independent components the concept of Service Oriented Architectures is applied. This facilitates communication between software systems utilizing standardized services that ensure interoperability. Thus, standards in the field of Geographic Information are inevitable for real-time spatial optimization. By exploiting the ability of mobile devices to determine the own position paired with standardized services Location Based Services are created. They are of interest in order to gather real-time data from mobile devices that are of importance for the optimization process itself. To optimize a given spatial problem, the universe of discourse has to be modeled accordingly. For the problem addressed in this thesis - Wood Supply Chain management - Graph theory is used. In addition, the problem of Wood Supply Chain management can be represented by a specific mathematical problem class, the Vehicle Routing problem - specifically the Vehicle Routing Problem with Pickup and Delivery and Time Windows. To optimize this problem class, exact and approximate solution techniques exist. Exact algorithms provide optimal solutions and guarantee their optimally, whereas approximate techniques - approximation algorithms or heuristics - do not guarantee that a global optimum is found. Nevertheless, the are capable of handling large problem instances in reasonable time. For optimizing the Wood Supply Chain Adaptive Large Neighborhood Search is selected as appropriate optimization technique

  11. Optimization of Time-Partitions for Mixed-Criticality Real-Time Distributed Embedded Systems

    DEFF Research Database (Denmark)

    Tamas-Selicean, Domitian; Pop, Paul

    2011-01-01

    In this paper we are interested in mixed-criticality embedded real-time applications mapped on distributed heterogeneous architectures. The architecture provides both spatial and temporal partitioning, thus enforcing enough separation for the critical applications. With temporal partitioning, each...

  12. Patient Safety in Interventional Radiology: A CIRSE IR Checklist.

    LENUS (Irish Health Repository)

    2012-02-01

    Interventional radiology (IR) is an invasive speciality with the potential for complications as with other invasive specialities. The World Health Organization (WHO) produced a surgical safety checklist to decrease the morbidity and mortality associated with surgery. The Cardiovascular and Interventional Society of Europe (CIRSE) set up a task force to produce a checklist for IR. Use of the checklist will, we hope, reduce the incidence of complications after IR procedures. It has been modified from the WHO surgical safety checklist and the RAD PASS from Holland.

  13. Amplitude and rise time compensated timing optimized for large semiconductor detectors

    International Nuclear Information System (INIS)

    The ARC timing described has excellent timing properties even when using a wide energy range, eg from 10 keV to over 1 MeV. The detector signal from a preamplifier is accepted directly by the unit as a timing filter amplifier with a sensitivity of 1 mV is incorporated. The adjustable rise time rejection feature makes it possible to achieve a good prompt time spectrum with symmetrical exponential shape down to less than 1/100 of the peak value. A complete schematic of the unit is given together with results of extensive tests of its performance. For example the time spectrum for (1330+-20) keV of 60Co taken with a 43 ccm Ge(Li) detector has the following parameters: FWHM=2.2 ns, FW(.1)M = 4.4 ns and FW(.01)M = 7.6 ns and for (50+-10) keV of 22Na the following was obtained: FWHM =10.8 ns, FW(.1)M =21.6 ns and FW(.01)M = 34.6 ns. In another experiment with two fast plastic scintillators (NE 102A) and using a 20 % dynamic energy range the following was measured FWHM =280 ps, FW(.1)M = 470 ps and FW(.01)M =710 ps. (Auth.)

  14. Robust Optimization for Time-Cost Tradeoff Problem in Construction Projects

    Directory of Open Access Journals (Sweden)

    Ming Li

    2014-01-01

    Full Text Available Construction projects are generally subject to uncertainty, which influences the realization of time-cost tradeoff in project management. This paper addresses a time-cost tradeoff problem under uncertainty, in which activities in projects can be executed in different construction modes corresponding to specified time and cost with interval uncertainty. Based on multiobjective robust optimization method, a robust optimization model for time-cost tradeoff problem is developed. In order to illustrate the robust model, nondominated sorting genetic algorithm-II (NSGA-II is modified to solve the project example. The results show that, by means of adjusting the time and cost robust coefficients, the robust Pareto sets for time-cost tradeoff can be obtained according to different acceptable risk level, from which the decision maker could choose the preferred construction alternative.

  15. Optimization of Time Restriction in Construction Project Management Using Lingo and M.S.Excel

    Directory of Open Access Journals (Sweden)

    Komal Kiran

    2015-09-01

    Full Text Available This study is an attempt to identify the minimum time of a construction project using the critical path method and linear programming model. A systematic analysis is attempted by developing a work breakdown structure for entire project to establish work elements for quantifying various resources against time and cost. A network is established taking into consideration all the predecessor and successor activities. The network is then optimized through crashing of activities so as to obtain optimal solution and serves as a base for optimizing total project cost. Finally, linear programming model is used to formulate the system of crashing network for minimum time by LINGO model and Microsoft Excel. These models consider many considerations of project thus reducing the duration of project. Ultimately, comparison of both the software outputs and the manual calculations is done and the best verifier is determined.

  16. Observer-based approximate optimal tracking control for time-delay systems with external disturbances

    Science.gov (United States)

    Su, Hao; Tang, Gong-You

    2016-09-01

    This paper proposes a successive approximation design approach of observer-based optimal tracking controllers for time-delay systems with external disturbances. To solve a two-point boundary value problem with time-delay and time-advance terms and obtain the optimal tracking control law, two sequences of vector differential equations are constructed first. Second, the convergence of the sequences of the vector differential equations is proved to guarantee the existence and uniqueness of the control law. Third, a design algorithm of the optimal tracking control law is presented and the physically realisable problem is addressed by designing a disturbance state observer and a reference input state observer. An example of an industrial electric heater is given to demonstrate the efficiency of the proposed approach.

  17. Fault detection and optimization for networked control systems with uncertain time-varying delay

    Institute of Scientific and Technical Information of China (English)

    Qing Wang; Zhaolei Wang; Chaoyang Dong; Erzhuo Niu

    2015-01-01

    The observer-based robust fault detection filter design and optimization for networked control systems (NCSs) with uncer-tain time-varying delays are addressed. The NCSs with uncertain time-varying delays are modeled as parameter-uncertain systems by the matrix theory. Based on the model, an observer-based residual generator is constructed and the sufficient condition for the existence of the desired fault detection filter is derived in terms of the linear matrix inequality. Furthermore, a time domain opti-mization approach is proposed to improve the performance of the fault detection system. To prevent the false alarms, a new thresh-old function is established, and the solution of the optimization problem is given by using the singular value decomposition (SVD) of the matrix. A numerical example is provided to il ustrate the effectiveness of the proposed approach.

  18. Estimation of the optimal statistical quality control sampling time intervals using a residual risk measure.

    Directory of Open Access Journals (Sweden)

    Aristides T Hatjimihail

    Full Text Available BACKGROUND: An open problem in clinical chemistry is the estimation of the optimal sampling time intervals for the application of statistical quality control (QC procedures that are based on the measurement of control materials. This is a probabilistic risk assessment problem that requires reliability analysis of the analytical system, and the estimation of the risk caused by the measurement error. METHODOLOGY/PRINCIPAL FINDINGS: Assuming that the states of the analytical system are the reliability state, the maintenance state, the critical-failure modes and their combinations, we can define risk functions based on the mean time of the states, their measurement error and the medically acceptable measurement error. Consequently, a residual risk measure rr can be defined for each sampling time interval. The rr depends on the state probability vectors of the analytical system, the state transition probability matrices before and after each application of the QC procedure and the state mean time matrices. As optimal sampling time intervals can be defined those minimizing a QC related cost measure while the rr is acceptable. I developed an algorithm that estimates the rr for any QC sampling time interval of a QC procedure applied to analytical systems with an arbitrary number of critical-failure modes, assuming any failure time and measurement error probability density function for each mode. Furthermore, given the acceptable rr, it can estimate the optimal QC sampling time intervals. CONCLUSIONS/SIGNIFICANCE: It is possible to rationally estimate the optimal QC sampling time intervals of an analytical system to sustain an acceptable residual risk with the minimum QC related cost. For the optimization the reliability analysis of the analytical system and the risk analysis of the measurement error are needed.

  19. Optimization of Partitioned Architectures to Support Soft Real-Time Applications

    DEFF Research Database (Denmark)

    Tamas-Selicean, Domitian; Pop, Paul

    2014-01-01

    In this paper we propose a new Tabu Search-based design optimization strategy for mixed-criticality systems implementing hard and soft real-time applications on the same platform. Our proposed strategy determined an implementation such that all hard real-time applications are schedulable and the ...... quality of service of the soft real-time tasks is maximized. We have evaluated our strategy using an aerospace case study....

  20. A checklist of reptiles of Kerala, India

    Directory of Open Access Journals (Sweden)

    Muhamed Jafer Palot

    2015-11-01

    Full Text Available A checklist of reptiles of Kerala State is presented, along with their Scientific, English and Malayalam names, endemic status, conservation status in the latest IUCN Red List category, different Schedules of Indian Wildlife (Protection Act and the Appendices of CITES.  A total of 173 species under 24 families belonging to three orders are recorded from Kerala.  Of these, 87 species are endemic to the Western Ghats, which include the 10 Kerala endemics.  Of the 173 species, 23 are listed in the various threatened categories of IUCN. 

  1. A checklist of reptiles of Kerala, India

    OpenAIRE

    Muhamed Jafer Palot

    2015-01-01

    A checklist of reptiles of Kerala State is presented, along with their Scientific, English and Malayalam names, endemic status, conservation status in the latest IUCN Red List category, different Schedules of Indian Wildlife (Protection) Act and the Appendices of CITES.  A total of 173 species under 24 families belonging to three orders are recorded from Kerala.  Of these, 87 species are endemic to the Western Ghats, which include the 10 Kerala endemics.  Of the 173 species, 23 are listed in ...

  2. Optimal time of soybean seed priming and primer effect under salt stress conditions

    OpenAIRE

    Miladinov Zlatica J.; Balešević-Tubić Svetlana N.; Đorđević Vuk B.; Đukić Vojin H.; Ilić Aleksandar D.; Čobanović Lazar M.

    2015-01-01

    The aim of this study was to examine optimal time of soybean seed priming and effect of primers under salt stress conditions. Testing was performed at the Institute of Field and Vegetable Crops, Novi Sad, on Galina seed variety. Optimal priming time was determined by immersing seed into: KNO3 (1%), H2O2 (0.1%), and H2O with the duration of 6 h, 12 h, 18 h, and 24 h. After drying until the initial moisture, the seed was placed for germination and after eight...

  3. Optimal Load Response to Time-of-Use Power Price for Demand Side Management in Denmark

    DEFF Research Database (Denmark)

    Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte

    2010-01-01

    -of-use power price for demand side management in order to save the energy costs as much as possible. 3 typical different kinds of loads (industrial load, residential load and commercial load) in Denmark are chosen as study cases. The energy costs decrease up to 9.6% with optimal load response to time......-of-use power price for different loads. Simulation results show that the optimal load response to time-of-use power price for demand side management generates different load profiles and reduces the load peaks. This kind of load patterns may also have significant effects on the power system normal operation....

  4. Optimal initial condition of passive tracers for their maximal mixing in finite time

    CERN Document Server

    Farazmand, Mohammad

    2016-01-01

    The efficiency of a fluid mixing device is often limited by fundamental laws and/or design constraints, such that a perfectly homogeneous mixture cannot be obtained in finite time. Here, we address the natural corollary question: Given the best available mixer, what is the optimal initial tracer pattern that leads to the most homogeneous mixture after a prescribed finite time? For ideal passive tracers, we show that this optimal initial condition coincides with the right singular vector (corresponding to the smallest singular value) of a suitably truncated Koopman operator. The truncation of the Koopman operator is made under the assumption that there is a small length-scale threshold $\\ell_\

  5. The optimal time-frequency atom search based on a modified ant colony algorithm

    Institute of Scientific and Technical Information of China (English)

    GUO Jun-feng; LI Yan-jun; YU Rui-xing; ZHANG Ke

    2008-01-01

    In this paper,a new optimal time-frequency atom search method based on a modified ant colony algorithm is proposed to improve the precision of the traditional methods.First,the discretization formula of finite length time-frequency atom is inferred at length.Second; a modified ant colony algorithm in continuous space is proposed.Finally,the optimal timefrequency atom search algorithm based on the modified ant colony algorithm is described in detail and the simulation experiment is carried on.The result indicates that the developed algorithm is valid and stable,and the precision of the method is higher than that of the traditional method.

  6. Design Optimization of Time- and Cost-Constrained Fault-Tolerant Distributed Embedded Systems

    DEFF Research Database (Denmark)

    Izosimov, Viacheslav; Pop, Paul; Eles, Petru;

    2005-01-01

    transient faults. Our design optimization approach decides the mapping of processes to processors and the assignment of fault-tolerant policies to processes such that transient faults are tolerated and the timing constraints of the application are satisfied. We present several heuristics which are able......In this paper we present an approach to the design optimization of fault-tolerant embedded systems for safety-critical applications. Processes are statically scheduled and communications are performed using the time-triggered protocol. We use process re-execution and replication for tolerating...

  7. Real time optimization of solar powered direct contact membrane distillation based on multivariable extremum seeking

    KAUST Repository

    Karam, Ayman M.

    2015-09-21

    This paper presents a real time optimization scheme for a solar powered direct contact membrane distillation (DCMD) water desalination system. The sun and weather conditions vary and are inconsistent throughout the day. Therefore, the solar powered DCMD feed inlet temperature is never constant, which influences the distilled water flux. The problem of DCMD process optimization has not been studied enough. In this work, the response of the process under various feed inlet temperatures is investigated, which demonstrates the need for an optimal controller. To address this issue, we propose a multivariable Newton-based extremum seeking controller which optimizes the inlet feed and permeate mass flow rates as the feed inlet temperature varies. Results are presented and discussed for a realistic temperature profile.

  8. Approximation methods of mixed l 1/H2 optimization problems for MIMO discrete-time systems

    Institute of Scientific and Technical Information of China (English)

    李昇平

    2004-01-01

    The mixed l1/H2 optimization problem for MIMO (multiple input-multiple output) discrete-time systems is eonsidered. This problem is formulated as minimizing the l1-norm of a dosed-loop transfer matrix while maintaining the H2-norm of another closed-loop transfer matrix at prescribed level. The continuity property of the optimal value in respect to changes in the H2-norm constraint is studied. The existence of the optimal solutions of mixed l1/H2 problem is proved. Becatse the solution of the mixed l1/H2 problem is based on the scaled-Q method, it avoids the zero interpolation difficulties. The convergent upper and lower bounds can be obtained by solving a sequence of finite dimensional nonlinear programming for which many efficient numerical optimization algorithms exist.

  9. Approximate optimal control for a class of nonlinear discrete-time systems with saturating actuators

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper, we solve the approximate optimal control problem for a class of nonlinear discrete-time systems with saturating actu- ators via greedy iterative Heuristic Dynamic Programming (GI-HDP) algorithm. In order to deal with the saturating problem of actu- ators, a novel nonquadratic functional is developed. Based on the nonquadratic functional, the GI-HDP algorithm is introduced to obtain the optimal saturated controller with a rigorous convergence analysis. For facilitating the implementation of the iterative algo- rithm, three neural networks are used to approximate the value function, compute the optimal control policy and model the unknown plant, respectively. An example is given to demonstrate the validity of the proposed optimal control scheme.

  10. A Space-Time Finite Element Model for Design and Control Optimization of Nonlinear Dynamic Response

    Directory of Open Access Journals (Sweden)

    P.P. Moita

    2008-01-01

    Full Text Available A design and control sensitivity analysis and multicriteria optimization formulation is derived for flexible mechanical systems. This formulation is implemented in an optimum design code and it is applied to the nonlinear dynamic response. By extending the spatial domain to the space-time domain and treating the design variables as control variables that do not change with time, the design space is included in the control space. Thus, one can unify in one single formulation the problems of optimum design and optimal control. Structural dimensions as well as lumped damping and stiffness parameters plus control driven forces, are considered as decision variables. The dynamic response and its sensitivity with respect to the design and control variables are discretized via space-time finite elements, and are integrated at-once, as it is traditionally used for static response. The adjoint system approach is used to determine the design sensitivities. Design optimization numerical examples are performed. Nonlinear programming and optimality criteria may be used for the optimization process. A normalized weighted bound formulation is used to handle multicriteria problems.

  11. Infection Control Full-time Team and Checklist in the Application of ICU in the Control of Multiple Drug Resistant Bacteria in Nosocomial Infection%感控专职小组联合查检单在ICU多重耐药菌医院感染控制中的应用

    Institute of Scientific and Technical Information of China (English)

    杜华; 秦存玲; 刘敏

    2016-01-01

    Objective To understand the application effect of a combined checklist for the infection control ful-time team in multidrug-resistant bacteria infection management.Methods To establish a multidrug-resistant bacteria infection control ful-time team, and introduce the quality management tool of “checklist” to intervene the hospital patients being infected with ICU MDRO.ResultsThe compliance rate and various indexes by taking prevention and control measures for the interfered group were improved(P<0.05),and the length of stay in ICU was shorter than that of the control group(P<0.05).Conclusion The combined checklist for the infection control ful-time team can promote compliance of the multidrug-resistant bacteria infection control and isolation measures, effectively improve various indexes for hospital infection management quality control of MDRO, and shorten the length of stay in ICU.%目的:了解感控专职小组联合查检单在多重耐药菌感染管理中应用的效果。方法成立多重耐药菌感控专职小组,引用“查检单”质量管理工具对ICU MDRO感染的住院患者进行干预。结果干预组防控措施依从率及各项指标均有改善(P<0.05);ICU住院时间也低于对照组(P<0.05)。结论感控专职小组联合查检单能提高多重耐药菌感染控制隔离措施依从性,有效改善MDRO医院感染管理质量控制的各项指标;缩短ICU住院时间。

  12. Optical tracking of contrast medium bolus to optimize bolus shape and timing in dynamic computed tomography

    Science.gov (United States)

    Eisa, Fabian; Brauweiler, Robert; Peetz, Alexander; Hupfer, Martin; Nowak, Tristan; Kalender, Willi A.

    2012-05-01

    One of the biggest challenges in dynamic contrast-enhanced CT is the optimal synchronization of scan start and duration with contrast medium administration in order to optimize image contrast and to reduce the amount of contrast medium. We present a new optically based approach, which was developed to investigate and optimize bolus timing and shape. The time-concentration curve of an intravenously injected test bolus of a dye is measured in peripheral vessels with an optical sensor prior to the diagnostic CT scan. The curves can be used to assess bolus shapes as a function of injection protocols and to determine contrast medium arrival times. Preliminary results for phantom and animal experiments showed the expected linear behavior between dye concentration and absorption. The kinetics of the dye was compared to iodinated contrast medium and was found to be in good agreement. The contrast enhancement curves were reliably detected in three mice with individual bolus shapes and delay times of 2.1, 3.5 and 6.1 s, respectively. The optical sensor appears to be a promising approach to optimize injection protocols and contrast enhancement timing and is applicable to all modalities without implying any additional radiation dose. Clinical tests are still necessary.

  13. Real-time and dynamic schedule optimization of construction projects on the basis of lean construction

    Institute of Scientific and Technical Information of China (English)

    QI Shen-jun; DING Lie-yun; LUO Han-bin; DONG Xiao-yan

    2007-01-01

    Lean construction has been newly applied to construction industry. The best performance of a project can be achieved through the precise definition of construction product, rational work break structure, lean supply chain, decrease of resources waste, objective control and so forth. Referring to the characteristics of schedule planning of construction projects and lean construction philosophy, we proposed optimizing methodology of real-time and dynamic schedule of construction projects based on lean construction. The basis of the methodology is process reorganization and lean supply in construction enterprises. The traditional estimating method of the activity duration is fuzzy and random; however, a newly proposed lean forecasting method employs multi-components linear-regression, back-propagation artificial neural networks and learning curve. Taking account of the limited resources and the fixed duration of a project, the optimizing method of the real-time and dynamic schedule adopts the concept of resource driving. To optimize the schedule of a construction project timely and effectively, an intellectualized schedule management system was developed. It can work out the initial schedule, optimize the real-time and dynamic schedule, and display the schedule with the Gant Chart, the net-work graph and the space-time line chart. A case study was also presented to explain the proposed method.

  14. Time-optimal control of a self-propelled particle in a spatiotemporal flow field

    Science.gov (United States)

    Bakolas, Efstathios; Marchidan, Andrei

    2016-03-01

    We address a minimum-time problem that constitutes an extension of the classical Zermelo navigation problem in higher dimensions. In particular, we address the problem of steering a self-propelled particle to a prescribed terminal position with free terminal velocity in the presence of a spatiotemporal flow field. Furthermore, we assume that the norm of the rate of change of the particle's velocity relative to the flow is upper bounded by an explicit upper bound. To address the problem, we first employ Pontryagin's minimum principle to parameterise the set of candidate time-optimal control laws in terms of a parameter vector that belongs to a compact set. Subsequently, we develop a simple numerical algorithm for the computation of the minimum time-to-come function that is tailored to the particular parametrisation of the set of the candidate time-optimal control laws of our problem. The proposed approach bypasses the task of converting the optimal control problem to a parameter optimisation problem, which can be computationally intense, especially when one is interested in characterising the optimal synthesis of the minimum-time problem. Numerical simulations that illustrate the theoretical developments are presented.

  15. Multiobjective Optimization for Electronic Circuit Design in Time and Frequency Domains

    Directory of Open Access Journals (Sweden)

    J. Dobes

    2013-04-01

    Full Text Available The multiobjective optimization provides an extraordinary opportunity for the finest design of electronic circuits because it allows to mathematically balance contradictory requirements together with possible constraints. In this paper, an original and substantial improvement of an existing method for the multiobjective optimization known as GAM (Goal Attainment Method is suggested. In our proposal, the GAM algorithm itself is combined with a procedure that automatically provides a set of parameters -- weights, coordinates of the reference point -- for which the method generates noninferior solutions uniformly spread over an appropriately selected part of the Pareto front. Moreover, the resulting set of obtained solutions is then presented in a suitable graphic form so that the solution representing the most satisfactory tradeoff can be easily chosen by the designer. Our system generates various types of plots that conveniently characterize results of up to four-dimensional problems. Technically, the procedures of the multiobjective optimization were created as a software add-on to the CIA (Circuit Interactive Analyzer program. This way enabled us to utilize many powerful features of this program, including the sensitivity analyses in time and frequency domains. As a result, the system is also able to perform the multiobjective optimization in the time domain and even highly nonlinear circuits can be significantly improved by our program. As a demonstration of this feature, a multiobjective optimization of a C-class power amplifier in the time domain is thoroughly described in the paper. Further, a four-dimensional optimization of a video amplifier is demonstrated with an original graphic representation of the Pareto front, and also some comparison with the weighting method is done. As an example of improving noise properties, a multiobjective optimization of a low-noise amplifier is performed, and the results in the frequency domain are shown

  16. The effects of initial conditions and control time on optimal actuator placement via a max-min Genetic Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Redmond, J. [Sandia National Labs., Albuquerque, NM (United States); Parker, G. [State Univ. of New York, Buffalo, NY (United States)

    1993-07-01

    This paper examines the role of the control objective and the control time in determining fuel-optimal actuator placement for structural vibration suppression. A general theory is developed that can be easily extended to include alternative performance metrics such as energy and time-optimal control. The performance metric defines a convex admissible control set which leads to a max-min optimization problem expressing optimal location as a function of initial conditions and control time. A solution procedure based on a nested Genetic Algorithm is presented and applied to an example problem. Results indicate that the optimal locations vary widely as a function of control time and initial conditions.

  17. Multi-objective Optimization of Controller for Process with Reverse Response and Dead Time

    Institute of Scientific and Technical Information of China (English)

    WANG Guo-liang; SHAO Hui-he

    2009-01-01

    Due to the difficulty of controlling the process with inverse response and dead time, a Multi-objective Optimization based on Genetic Algorithm (MOGA) method for tuning of proportional-integral-derivative (PID) controller is proposed. The settings of the controller are valued by two criteria, the error between output and reference signals and control moves. An appropriate set of Pareto optimal setting of the PID controller is founded by analyzing the results of Pareto optimal surfaces for balancing the two criteria. A high order process with inverse response and dead time is used to illustrate the results of the proposed method. And the efficiency and robustness of the tuning method are evident compared with methods in recent literature.

  18. Finite-Time Anti-Disturbance Inverse Optimal Attitude Tracking Control of Flexible Spacecraft

    Directory of Open Access Journals (Sweden)

    Chutiphon Pukdeboon

    2013-01-01

    Full Text Available We propose a new robust optimal control strategy for flexible spacecraft attitude tracking maneuvers in the presence of external disturbances. An inverse optimal control law is designed based on a Sontag-type formula and a control Lyapunov function. An adapted extended state observer is used to compensate for the total disturbances. The proposed controller can be expressed as the sum of an inverse optimal control and an adapted extended state observer. It is shown that the developed controller can minimize a cost functional and ensure the finite-time stability of a closed-loop system without solving the associated Hamilton-Jacobi-Bellman equation directly. For an adapted extended state observer, the finite-time convergence of estimation error dynamics is proven using a strict Lyapunov function. An example of multiaxial attitude tracking maneuvers is presented and simulation results are included to show the performance of the developed controller.

  19. Optimal Resource Allocation and Relay Selection in Bandwidth and Time Exchange Based Cooperative Forwarding

    CERN Document Server

    Islam, Muhammad Nazmul; Kompella, Sastry

    2011-01-01

    In this paper, we investigate joint optimal relay selection and resource allocation that are fundamental to the understanding of bandwidth exchange (BE) and time exchange (TE) enabled incentivized cooperative forwarding in wireless networks. We consider a network where N nodes transmit data in the uplink to an access point (AP) or base station (BS). We first consider the scenario where each node gets an initial amount (equal, optimal or arbitrary) of resource in the form of bandwidth or time, and uses this resource as a flexible incentive for two hop relaying. We focus on ?-fair network utility maximization (NUM) and total power minimization in this environment. For both BE and TE, we show the concavity or convexity of the resource allocation problem for a fixed relay set. Defining the link weights of each relay pair as the utility gain due to cooperation (over noncooperation), we show that the optimal relay selection, often a combinatorially cumbersome problem, reduces to the maximum weighted matching (MWM) ...

  20. A simplification of the backpropagation-through-time algorithm for optimal neurocontrol.

    Science.gov (United States)

    Bersini, H; Gorrini, V

    1997-01-01

    Backpropagation-through-time (BPTT) is the temporal extension of backpropagation which allows a multilayer neural network to approximate an optimal state-feedback control law provided some prior knowledge (Jacobian matrices) of the process is available. In this paper, a simplified version of the BPTT algorithm is proposed which more closely respects the principle of optimality of dynamic programming. Besides being simpler, the new algorithm is less time-consuming and allows in some cases the discovery of better control laws. A formal justification of this simplification is attempted by mixing the Lagrangian calculus underlying BPTT with Bellman-Hamilton-Jacobi equations. The improvements due to this simplification are illustrated by two optimal control problems: the rendezvous and the bioreactor. PMID:18255645

  1. Effect of wind turbine response time on optimal dynamic induction control of wind farms

    Science.gov (United States)

    Munters, Wim; Meyers, Johan

    2016-09-01

    In this work, we extend recent research efforts on induction-based optimal control in large-eddy simulations of wind farms in the turbulent atmospheric boundary layer. More precisely, we investigate the effect of wind turbine response time to requested power setpoints on achievable power gains. We do this by including a time-filtering of the thrust coefficient setpoints in the optimal control framework. We consider simulation cases restricted to underinduction compared to the Betz limit, as well as cases that also allow overinduction. Optimization results show that, except for the most restrictive underinductive slow-response case, all cases still yield increases in energy extraction in the order of 10% and more.

  2. Average Sample-path Optimality for Continuous-time Markov Decision Processes in Polish Spaces

    Institute of Scientific and Technical Information of China (English)

    Quan-xin ZHU

    2011-01-01

    In this paper we study the average sample-path cost (ASPC) problem for continuous-time Markov decision processes in Polish spaces.To the best of our knowledge,this paper is a first attempt to study the ASPC criterion on continuous-time MDPs with Polish state and action spaces.The corresponding transition rates are allowed to be unbounded,and the cost rates may have neither upper nor lower bounds.Under some mild hypotheses,we prove the existence of e (ε ≥ 0)-ASPC optimal stationary policies based on two different approaches:one is the “optimality equation” approach and the other is the “two optimality inequalities” approach.

  3. Road maintenance optimization through a discrete-time semi-Markov decision process

    International Nuclear Information System (INIS)

    Optimization models are necessary for efficient and cost-effective maintenance of a road network. In this regard, road deterioration is commonly modeled as a discrete-time Markov process such that an optimal maintenance policy can be obtained based on the Markov decision process, or as a renewal process such that an optimal maintenance policy can be obtained based on the renewal theory. However, the discrete-time Markov process cannot capture the real time at which the state transits while the renewal process considers only one state and one maintenance action. In this paper, road deterioration is modeled as a semi-Markov process in which the state transition has the Markov property and the holding time in each state is assumed to follow a discrete Weibull distribution. Based on this semi-Markov process, linear programming models are formulated for both infinite and finite planning horizons in order to derive optimal maintenance policies to minimize the life-cycle cost of a road network. A hypothetical road network is used to illustrate the application of the proposed optimization models. The results indicate that these linear programming models are practical for the maintenance of a road network having a large number of road segments and that they are convenient to incorporate various constraints on the decision process, for example, performance requirements and available budgets. Although the optimal maintenance policies obtained for the road network are randomized stationary policies, the extent of this randomness in decision making is limited. The maintenance actions are deterministic for most states and the randomness in selecting actions occurs only for a few states.

  4. Multiobjective Dynamic Vehicle Routing Problem and Time Seed Based Solution Using Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Omprakash Kaiwartya

    2015-01-01

    Full Text Available A multiobjective dynamic vehicle routing problem (M-DVRP has been identified and a time seed based solution using particle swarm optimization (TS-PSO for M-DVRP has been proposed. M-DVRP considers five objectives, namely, geographical ranking of the request, customer ranking, service time, expected reachability time, and satisfaction level of the customers. The multiobjective function of M-DVRP has four components, namely, number of vehicles, expected reachability time, and profit and satisfaction level. Three constraints of the objective function are vehicle, capacity, and reachability. In TS-PSO, first of all, the problem is partitioned into smaller size DVRPs. Secondly, the time horizon of each smaller size DVRP is divided into time seeds and the problem is solved in each time seed using particle swarm optimization. The proposed solution has been simulated in ns-2 considering real road network of New Delhi, India, and results are compared with those obtained from genetic algorithm (GA simulations. The comparison confirms that TS-PSO optimizes the multiobjective function of the identified problem better than what is offered by GA solution.

  5. Reducing acquisition times in multidimensional NMR with a time-optimized Fourier encoding algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhiyong [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian 361005 (China); Smith, Pieter E. S.; Frydman, Lucio, E-mail: lucio.frydman@weizmann.ac.il [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel)

    2014-11-21

    Speeding up the acquisition of multidimensional nuclear magnetic resonance (NMR) spectra is an important topic in contemporary NMR, with central roles in high-throughput investigations and analyses of marginally stable samples. A variety of fast NMR techniques have been developed, including methods based on non-uniform sampling and Hadamard encoding, that overcome the long sampling times inherent to schemes based on fast-Fourier-transform (FFT) methods. Here, we explore the potential of an alternative fast acquisition method that leverages a priori knowledge, to tailor polychromatic pulses and customized time delays for an efficient Fourier encoding of the indirect domain of an NMR experiment. By porting the encoding of the indirect-domain to the excitation process, this strategy avoids potential artifacts associated with non-uniform sampling schemes and uses a minimum number of scans equal to the number of resonances present in the indirect dimension. An added convenience is afforded by the fact that a usual 2D FFT can be used to process the generated data. Acquisitions of 2D heteronuclear correlation NMR spectra on quinine and on the anti-inflammatory drug isobutyl propionic phenolic acid illustrate the new method's performance. This method can be readily automated to deal with complex samples such as those occurring in metabolomics, in in-cell as well as in in vivo NMR applications, where speed and temporal stability are often primary concerns.

  6. "You're never really off time": Healthcare providers' interpretations of optimal timing for HPV vaccination.

    Science.gov (United States)

    Henrikson, Nora B; Tuzzio, Leah; Gilkey, Melissa B; McRee, Annie-Laurie

    2016-12-01

    Healthcare providers have a strong influence on human papillomavirus (HPV) vaccination decisions, yet they often fail to recommend the vaccine to the 11- and 12-year-olds who are targeted by practice guidelines. We sought to understand how providers interpret and value age-based guidelines. We conducted a secondary analysis of data from two qualitative studies of healthcare providers' HPV vaccination attitudes and practices. Participants were physicians, nurse practitioners, and physician assistants in Minnesota (n = 27) and in Washington (n = 17) interviewed in 2012 and 2014 respectively. Verbatim transcripts from each study were analyzed independently using content analysis, and collective findings were then jointly analyzed. The research team worked via consensus to derive codes and describe representative themes. A high proportion of providers reported either a lack of concern about HPV vaccine completion, or concern beginning several years past the recommended target age. Many providers perceived a gradient of HPV vaccination timeliness ranging from age 12 to 26. Instead of age-based recommendations, providers timed recommendations based on perceptions of access to care and patient risk. They often offered "gentle" recommendations and deferred vaccination discussions as a tool to building trust with families. Interventions aimed at helping providers deliver effective recommendations for timely HPV vaccination are needed. Our findings suggest that changing the norm of provider culture to one in which "catch-up" schedules are seen as a suboptimal way to achieve vaccine uptake may be an important goal. PMID:27413667

  7. Simultaneous Optimization of Container Ship Sailing Speed and Container Routing with Transit Time Restrictions

    DEFF Research Database (Denmark)

    Karsten, Christian Vad; Røpke, Stefan; Pisinger, David

    We introduce a decision support tool for liner shipping companies to optimally determine the sailing speed and needed fleet for a global network. As a novelty we incorporate cargo routing decisions with tight transit time restrictions on each container such that we get a realistic picture...

  8. Time and Power Optimizations in FPGA-Based Architectures for Polyphase Channelizers

    DEFF Research Database (Denmark)

    Awan, Mehmood-Ur-Rehman; Harris, Fred; Koch, Peter

    2012-01-01

    This paper presents the time and power optimization considerations for Field Programmable Gate Array (FPGA) based architectures for a polyphase filter bank channelizer with an embedded square root shaping filter in its polyphase engine. This configuration performs two different re-sampling tasks ...

  9. Real-time sail and heading optimization for a surface sailing vessel by extremum seeking control

    DEFF Research Database (Denmark)

    Treichel, Kai; Jouffroy, Jerome

    2010-01-01

    In this paper we develop a simplified mathematical model representing the main elements of the behaviour of sailing vessels as a basis for simulation and controller design. For adaptive real-time optimization of the sail and heading angle we then apply extremum seeking control (which is a gradient...

  10. Optimal One Bit Time Reversal For UWB Impulse Radio In Multi-User Wireless Communications

    DEFF Research Database (Denmark)

    Nguyen, Hung Tuan

    2008-01-01

    In this paper, with the purpose of further reducing the complexity of the system, while keeping its temporal and spatial focusing performance, we investigate the possibility of using optimal one bit time reversal (TR) system for impulse radio ultra wideband multi-user wireless communications. The...

  11. Optimized Schwarz waveform relaxation and discontinuous Galerkin time stepping for heterogeneous problems

    CERN Document Server

    Halpern, Laurence; Japhet, Caroline

    2010-01-01

    We design and analyze a Schwarz waveform relaxation algorithm for domain decomposition of advection-diffusion-reaction problems with strong heterogeneities. The interfaces are curved, and we use optimized Robin or Ventcell transmission conditions. We analyze the semi-discretization in time with Discontinuous Galerkin as well. We also show two-dimensional numerical results using generalized mortar finite elements in space.

  12. Low-power Terahertz Time-Domain Spectroscopy with optimized electro-optical detection

    DEFF Research Database (Denmark)

    Gorenflo, Stefan; Hinkov, Iliyana; Lambrecht, Armin;

    2005-01-01

    A Terahertz Time-Domain Spectroscopy (THz-TDS) system with electro-optical detector based on a ZnTe crystal is presented. The pump laser is a Ti:Sa laser with pulse duration of approx. 10 fs at a central wavelength of 800 nm. Using an optimized detection configuration, a signal-to-noise ratio...

  13. RTRO–Coal: Real-Time Resource-Reconciliation and Optimization for Exploitation of Coal Deposits

    NARCIS (Netherlands)

    Benndorf, J.; Yueksel, C.; Soleymani, M.; Rosenberg, H.; Thielemann, T.; Mittmann, R.; Lohsträter, O.M.; Lindig, M.; Minnecker, C.; Donner, R.; Naworyta, W.

    2015-01-01

    This contribution presents an innovative and integrated framework for real-time-process reconciliation and optimization (RTRO) in large continuous open pit coal mines. RTRO-Coal is currently developed, validated, tested and implemented as part of a multi-national multi-partner European Union funded

  14. Tight Bounds on the Optimization Time of a Randomized Search Heuristic on Linear Functions

    DEFF Research Database (Denmark)

    Witt, Carsten

    2013-01-01

    The analysis of randomized search heuristics on classes of functions is fundamental to the understanding of the underlying stochastic process and the development of suitable proof techniques. Recently, remarkable progress has been made in bounding the expected optimization time of a simple evolut...

  15. Optimal discrete-time dynamic output-feedback design - A w-domain approach

    Science.gov (United States)

    Ha, Cheolkeun; Ly, Uy-Loi

    1991-01-01

    An alternative method for optimal digital control design is described in this paper. The method is based on the usage of the w-transform and has many attractive design features. One of these is its immediate connection with frequency loop-shaping techniques that are now popular and effective for multivariable control synthesis in continuous-time domain. Furthermore, any design algorithms originally developed for continuous-time systems can now be immediately extended to the discrete-time domain. The main results presented in this paper are the exact problem formulation and solution of an optimal discrete-time dynamic output-feedback design in the w-domain involving a quadratic performance index to random disturbances. In addition, necessary conditions for optimality are obtained for the numerical solution of the optimal output-feedback compensator design. A numerical example is presented illustrating its application to the design of a low-order dynamic compensator in a stability augmentation system of a commercial transport.

  16. Optimized Distributed Feedback Dye Laser Sensor for Real-Time Monitoring of Small Molecule Diffusion

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Smith, Cameron; Dufva, Martin;

    2014-01-01

    parameter for optimization. Using such laser sensors in an imaging spectroscopy setup, real-time label-free monitoring of sugar molecule diffusion in water is demonstrated. This method could potentially pave the way towards the analysis of small molecule diffusion in various media, e.g. protein signaling...... processes in tissue....

  17. Optimizing headspace sampling temperature and time for analysis of volatile oxidation products in fish oil

    DEFF Research Database (Denmark)

    Rørbæk, Karen; Jensen, Benny

    1997-01-01

    Headspace-gas chromatography (HS-GC), based on adsorption to Tenax GR(R), thermal desorption and GC, has been used for analysis of volatiles in fish oil. To optimize sam sampling conditions, the effect of heating the fish oil at various temperatures and times was evaluated from anisidine values (...

  18. The Effects of Creatine Supplementation on Explosive Performance and Optimal Individual Postactivation Potentiation Time

    Directory of Open Access Journals (Sweden)

    Chia-Chi Wang

    2016-03-01

    Full Text Available Creatine plays an important role in muscle energy metabolism. Postactivation potentiation (PAP is a phenomenon that can acutely increase muscle power, but it is an individualized process that is influenced by muscle fatigue. This study examined the effects of creatine supplementation on explosive performance and the optimal individual PAP time during a set of complex training bouts. Thirty explosive athletes performed tests of back squat for one repetition maximum (1RM strength and complex training bouts for determining the individual optimal timing of PAP, height and peak power of a counter movement jump before and after the supplementation. Subjects were assigned to a creatine or placebo group and then consumed 20 g of creatine or carboxymethyl cellulose per day for six days. After the supplementation, the 1RM strength in the creatine group significantly increased (p < 0.05. The optimal individual PAP time in the creatine group was also significant earlier than the pre-supplementation and post-supplementation of the placebo group (p < 0.05. There was no significant difference in jump performance between the groups. This study demonstrates that creatine supplementation improves maximal muscle strength and the optimal individual PAP time of complex training but has no effect on explosive performance.

  19. Move-optimal schedules for parallel machines to minimize total weighted completion time

    NARCIS (Netherlands)

    Brueggemann, T.; Hurink, J.L.; Kern, W.

    2005-01-01

    We study the minimum total weighted completion time problem on identical machines, which is known to be strongly $\\mathcal{NP}$-hard. We analyze a simple local search heuristic, moving jobs from one machine to another. The local optima can be shown to be approximately optimal with approximation rati

  20. How to study optimal timing of PET/CT for monitoring of cancer treatment

    DEFF Research Database (Denmark)

    Vach, Werner; Høilund-Carlsen, Poul Flemming; Fischer, Barbara Malene Bjerregaard;

    2011-01-01

    Purpose: The use of PET/CT for monitoring treatment response in cancer patients after chemo- or radiotherapy is a very promising approach to optimize cancer treatment. However, the timing of the PET/CT-based evaluation of reduction in viable tumor tissue is a crucial question. We investigated how...

  1. Space-time topology optimization for one-dimensional wave propagation

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard

    2009-01-01

    -dimensional transient wave propagation in an elastic rod with time dependent Young's modulus. By two simulation examples it is demonstrated how dynamic structures can display rich dynamic behavior such as wavenumber/frequency shifts and lack of energy conservation. The optimization method's potential for creating...

  2. Economically optimal timing for crop disease control under uncertainty: an options approach

    NARCIS (Netherlands)

    Ndeffo Mbah, M.L.; Forster, G.; Wesseler, J.H.H.; Gilligan, C.A.

    2010-01-01

    Severe large-scale disease and pest infestations in agricultural regions can cause significant economic damage. Understanding if and when disease control measures should be taken in the presence of risk and uncertainty is a key issue. We develop a framework to examine the economically optimal timing

  3. The Optimization of Transportation Costs in Logistics Enterprises with Time-Window Constraints

    Directory of Open Access Journals (Sweden)

    Qingyou Yan

    2015-01-01

    Full Text Available This paper presents a model for solving a multiobjective vehicle routing problem with soft time-window constraints that specify the earliest and latest arrival times of customers. If a customer is serviced before the earliest specified arrival time, extra inventory costs are incurred. If the customer is serviced after the latest arrival time, penalty costs must be paid. Both the total transportation cost and the required fleet size are minimized in this model, which also accounts for the given capacity limitations of each vehicle. The total transportation cost consists of direct transportation costs, extra inventory costs, and penalty costs. This multiobjective optimization is solved by using a modified genetic algorithm approach. The output of the algorithm is a set of optimal solutions that represent the trade-off between total transportation cost and the fleet size required to service customers. The influential impact of these two factors is analyzed through the use of a case study.

  4. Time, entropy generation, and optimization in low-dissipation heat devices

    Science.gov (United States)

    Calvo Hernández, A.; Medina, A.; Roco, J. M. M.

    2015-07-01

    We present new results obtained from the Carnot-like low-dissipation model of heat devices when size- and time-constraints are taken into account, in particular those obtained from the total cycle time and the contact times of the working system with the external heat reservoirs. The influence of these constraints and of the characteristic time scale of the model on the entropy generation allows for a clear and unified interpretation of different energetic properties for both heat engines and refrigerators (REs). Some conceptual subtleties with regard to different optimization criteria, especially for REs, are discussed. So, the different status of power input, cooling power, and the unified figure of merit χ are analyzed on the basis of their absolute or local role as optimization criteria.

  5. Optimizing Completion Time and Energy Consumption in a Bidirectional Relay Network

    DEFF Research Database (Denmark)

    Liu, Huaping; Sun, Fan; Thai, Chan;

    2012-01-01

    arises for the minimal required energy. While the requirement for minimal energy consumption is obvious, the shortest completion time is relevant when certain multi-node network needs to reserve the wireless medium in order to carry out the data exchange among its nodes. The completion time....../energy consumption required for multiple flows depends on the current channel realizations, transmission methods used and, notably, the relation between the data sizes of different source nodes. In this paper we investigate the shortest completion time and minimal energy consumption in a two-way relay wireless...... uses Decode-and-Forward (DF), each of them is a quadratic optimization problem. The results show that, for given channel realizations, there is an optimal ratio of the data packets at the sources to obtain minimal completion time or energy consumption. This can be used as a guidance for the nodes...

  6. A preliminaryfloristic checklist of thal desert punjab, pakistan

    International Nuclear Information System (INIS)

    The floristic survey of the Thal desert, Punjab, Pakistan was carried out during 2010 to 2013. So far, 248 species distributed across 166 genera and 38 families were identified during the report period. Besides, one species viz., Themeda triandra was recorded for the first time from Pakistan. Of them, one fern, 4 monocots and 33 dicots families were determined. The most dominating family was Poaceae that contributed 52 species (21.49%), followed by Fabaceae (34 spp., 13.05%) and Amaranthaceae and Asteraceae (17 spp., 7.02% each). The largest genera were Euphorbia (6 spp.), Cyperus, Eragrostis and Solanum (5 spp. each), Mollugo, Heliotropium and Cenchrus (4 spp. each), Acacia, Prosopis, Tephrosia, Corchorus, Boerhavia and Ziziphus (3 spp. each). This checklist consists of updated systematic families and plants names that will provide a useful starting point for further ecological and bioprospective research of the area under study. (author)

  7. Optimal Compensation with Hidden Action and Lump-Sum Payment in a Continuous-Time Model

    International Nuclear Information System (INIS)

    We consider a problem of finding optimal contracts in continuous time, when the agent's actions are unobservable by the principal, who pays the agent with a one-time payoff at the end of the contract. We fully solve the case of quadratic cost and separable utility, for general utility functions. The optimal contract is, in general, a nonlinear function of the final outcome only, while in the previously solved cases, for exponential and linear utility functions, the optimal contract is linear in the final output value. In a specific example we compute, the first-best principal's utility is infinite, while it becomes finite with hidden action, which is increasing in value of the output. In the second part of the paper we formulate a general mathematical theory for the problem. We apply the stochastic maximum principle to give necessary conditions for optimal contracts. Sufficient conditions are hard to establish, but we suggest a way to check sufficiency using non-convex optimization

  8. Validation of a food checklist for oncology patients

    OpenAIRE

    Amend, Christa

    1993-01-01

    A Food Checklist, based on the Food Guide pyramid, was developed and validated as a quick method to determine the adequacy of dietary energy and protein intakes in cancer patients. Food intake data were monitored for 34 hospitalized oncology patients for two days. Caloric and protein intake estimates computed using the Food Checklist were correlated 0.99 (p

  9. Online Course Quality Assurance: Development of a Quality Checklist

    Science.gov (United States)

    McGahan, Steven J.; Jackson, Christina M.; Premer, Karen

    2015-01-01

    The University of Nebraska at Kearney's Online Course Checklist is the main instrument for assessing the quality of online courses at UNK. A number of issues were faced when developing and deploying this quality assurance checklist at a small four-year university. The process including development, implementation, and revision is discussed along…

  10. Haar Wavelet and Its Application in Optimal Control of Linear Time-invariant Systems

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    This paper uses Haar wavelet integral operational matrices to approximate the s olution of the optimal control problem with quadratic performance measures. The method reduces the original problem to the solution of linear algebraic equati ons. Hence, the computational difficulties are considerably reduced. Since Haar wavelet bases cooperate time-frequency localization, the system solution includ es both frequency information and time information. Other orthogonal functions do not have this property. An example shows that the results are ve ry accurate.

  11. Lyapunov matrices approach to the parametric optimization of time-delay systems

    Directory of Open Access Journals (Sweden)

    Duda Józef

    2015-09-01

    Full Text Available In the paper a Lyapunov matrices approach to the parametric optimization problem of time-delay systems with a P-controller is presented. The value of integral quadratic performance index of quality is equal to the value of Lyapunov functional for the initial function of the time-delay system. The Lyapunov functional is determined by means of the Lyapunov matrix

  12. Real-time Terrain Rendering using Smooth Hardware Optimized Level of Detail

    DEFF Research Database (Denmark)

    Larsen, Bent Dalgaard; Christensen, Niels Jørgen

    2003-01-01

    We present a method for real-time level of detail reduction that is able to display high-complexity polygonal surface data. A compact and efficient regular grid representation is used. The method is optimized for modern, low-end consumer 3D graphics cards. We avoid sudden changes of the geometry...... minimal pre-processing. We believe that this is the first time that a smooth level of detail has been implemented in commodity hardware....

  13. Optimal Decision for Fashion Supply Chains with Service Level Constraint and Controllable Lead Time

    OpenAIRE

    Guo Li; Yu-chen Kang; Guan Xu

    2015-01-01

    We study a two-echelon supply chain inventory model with controllable lead time and service level constraint in fashion supply chains, in which we assume that the unit cost of compressing lead time follows exponential distribution. Under these conditions we investigate the optimal ordering quantity and production quantity in the fashion supply chain by minimizing the joint total cost. Simultaneously, we work out the boundaries of ordering quantity and production quantity, which simplify the ...

  14. Optimal filtering of dynamics in short-time features for music organization

    OpenAIRE

    Arenas-García, Jerónimo; Larsen, Jan; Hansen, Lars Kai; Meng, Anders

    2006-01-01

    There is an increasing interest in customizable methods for organizing music collections. Relevant music characterization can be obtained from short-time features, but it is not obvious how to combine them to get useful information. In this work, a novel method, denoted as the Positive Constrained Orthonormalized Partial Least Squares (POPLS), is proposed. Working on the periodograms of MFCCs time series, this supervised method finds optimal filters which pick up the most discriminative tempo...

  15. Real-Time Inverse Optimal Neural Control for Image Based Visual Servoing with Nonholonomic Mobile Robots

    Directory of Open Access Journals (Sweden)

    Carlos López-Franco

    2015-01-01

    Full Text Available We present an inverse optimal neural controller for a nonholonomic mobile robot with parameter uncertainties and unknown external disturbances. The neural controller is based on a discrete-time recurrent high order neural network (RHONN trained with an extended Kalman filter. The reference velocities for the neural controller are obtained with a visual sensor. The effectiveness of the proposed approach is tested by simulations and real-time experiments.

  16. Optimizing time and resource allocation trade-offs for investment into morphological and behavioral defense

    DEFF Research Database (Denmark)

    Steiner, Uli; Pfeiffer, Thomas

    2007-01-01

    Prey organisms are confronted with time and resource allocation trade-offs. Time allocation trade-offs partition time, for example, between foraging effort to acquire resources and behavioral defense. Resource allocation trade-offs partition the acquired resources between multiple traits......, such as growth or morphological defense. We develop a mathematical model for prey organisms that comprise time and resource allocation trade-offs for multiple defense traits. Fitness is determined by growth and survival during ontogeny. We determine optimal defense strategies for environments that differ...

  17. Optimized Crossover Genetic Algorithm for Vehicle Routing Problem with Time Windows

    Directory of Open Access Journals (Sweden)

    H. Nazif

    2010-01-01

    Full Text Available Problem statement: In this study, we considered the application of a genetic algorithm to vehicle routing problem with time windows where a set of vehicles with limits on capacity and travel time are available to service a set of customers with demands and earliest and latest time for serving. The objective is to find routes for the vehicles to service all the customers at a minimal cost without violating the capacity and travel time constraints of the vehicles and the time window constraints set by the customers. Approach: We proposed a genetic algorithm using an optimized crossover operator designed by a complete undirected bipartite graph that finds an optimal set of delivery routes satisfying the requirements and giving minimal total cost. Various techniques have also been introduced into the proposed algorithm to further enhance the solutions quality. Results: We tested our algorithm with benchmark instances and compared it with some other heuristics in the literature. The results showed that the proposed algorithm is competitive in terms of the quality of the solutions found. Conclusion/Recommendations: This study presented a genetic algorithm for solving vehicle routing problem with time windows using an optimized crossover operator. From the results, it can be concluded that the proposed algorithm is competitive when compared with other heuristics in the literature.

  18. Checklists to improve the quality of the orthopaedic literature

    Directory of Open Access Journals (Sweden)

    Mundi Raman

    2008-01-01

    Full Text Available Several checklists have been developed in an effort to help journals and researchers improve the quality of reporting in research. The CONSORT statement and the CLEAR NPT evaluate randomized trials. The MOOSE and QUOROM checklists evaluate meta-analyses. The STROBE checklists assists readers in evaluating observational studies and the STARD checklist was developed for diagnostic test evaluation. The checklists presented here provide an invaluable source of guidance to authors, journal editors and readers who are seeking to prepare and evaluate reports. As evidence-based medicine continues to establish itself as the new paradigm by which medicine is practiced, the need for good reporting for all research designs must also become commonplace as opposed to the exception.

  19. Input price risk and optimal timing of energy investment: choice between fossil- and biofuels

    International Nuclear Information System (INIS)

    We consider energy investment, when a choice has to be made between fossil fuel and biomass fired production technologies. A dynamic model is presented to illustrate the effect of the different degrees of input price uncertainty on the choice of technology and the timing of the investment. It is shown that when the choice of technology is irreversible, it may be optimal to postpone the investment even if it would otherwise be optimal to invest in one or both of the plant types. We provide a numerical example based on cost, estimates of two different power plant types. (author)

  20. Input price risk and optimal timing of energy investment: choice between fossil- and biofuels

    Energy Technology Data Exchange (ETDEWEB)

    Murto, Pauli; Nese, Gjermund

    2002-05-01

    We consider energy investment, when a choice has to be made between fossil fuel and biomass fired production technologies. A dynamic model is presented to illustrate the effect of the different degrees of input price uncertainty on the choice of technology and the timing of the investment. It is shown that when the choice of technology is irreversible, it may be optimal to postpone the investment even if it would otherwise be optimal to invest in one or both of the plant types. We provide a numerical example based on cost, estimates of two different power plant types. (author)

  1. Computational methods for optimal linear-quadratic compensators for infinite dimensional discrete-time systems

    Science.gov (United States)

    Gibson, J. S.; Rosen, I. G.

    1986-01-01

    An abstract approximation theory and computational methods are developed for the determination of optimal linear-quadratic feedback control, observers and compensators for infinite dimensional discrete-time systems. Particular attention is paid to systems whose open-loop dynamics are described by semigroups of operators on Hilbert spaces. The approach taken is based on the finite dimensional approximation of the infinite dimensional operator Riccati equations which characterize the optimal feedback control and observer gains. Theoretical convergence results are presented and discussed. Numerical results for an example involving a heat equation with boundary control are presented and used to demonstrate the feasibility of the method.

  2. Input price risk and optimal timing of energy investment: choice between fossil- and biofuels

    OpenAIRE

    Murto, Pauli; Nese, Gjermund

    2002-01-01

    We consider energy investment, when a choice has to be made between fossil fuel and biomass fired production technologies. A dynamic model is presented to illustrate the effect of the different degrees of input price uncertainty on the choice of technology and the timing of the investment. It is shown that when the choice of technology is irreversible, it may be optimal to postpone the investment even if it would otherwise be optimal to invest in one or both of the plant types. We provide a n...

  3. Multi-Objective Optimization of Traffic Signal Timing for Oversaturated Intersection

    Directory of Open Access Journals (Sweden)

    Yan Li

    2013-01-01

    Full Text Available For the purpose of improving the efficiency of traffic signal control for isolate intersection under oversaturated conditions, a multi-objective optimization algorithm for traffic signal control is proposed. Throughput maximum and average queue ratio minimum are selected as the optimization objectives of the traffic signal control under oversaturated condition. A simulation environment using VISSIM SCAPI was utilized to evaluate the convergence and the optimization results under various settings and traffic conditions. It is written by C++/CRL to connect the simulation software VISSIM and the proposed algorithm. The simulation results indicated that the signal timing plan generated by the proposed algorithm has good efficiency in managing the traffic flow at oversaturated intersection than the commonly utilized signal timing optimization software Synchro. The update frequency applied in the simulation environment was 120 s, and it can meet the requirements of signal timing plan update in real filed. Thus, the proposed algorithm has the capability of searching Pareto front of the multi-objective problem domain under both normal condition and over-saturated condition.

  4. Neural network approach to continuous-time direct adaptive optimal control for partially unknown nonlinear systems.

    Science.gov (United States)

    Vrabie, Draguna; Lewis, Frank

    2009-04-01

    In this paper we present in a continuous-time framework an online approach to direct adaptive optimal control with infinite horizon cost for nonlinear systems. The algorithm converges online to the optimal control solution without knowledge of the internal system dynamics. Closed-loop dynamic stability is guaranteed throughout. The algorithm is based on a reinforcement learning scheme, namely Policy Iterations, and makes use of neural networks, in an Actor/Critic structure, to parametrically represent the control policy and the performance of the control system. The two neural networks are trained to express the optimal controller and optimal cost function which describes the infinite horizon control performance. Convergence of the algorithm is proven under the realistic assumption that the two neural networks do not provide perfect representations for the nonlinear control and cost functions. The result is a hybrid control structure which involves a continuous-time controller and a supervisory adaptation structure which operates based on data sampled from the plant and from the continuous-time performance dynamics. Such control structure is unlike any standard form of controllers previously seen in the literature. Simulation results, obtained considering two second-order nonlinear systems, are provided. PMID:19362449

  5. Real-time PCR probe optimization using design of experiments approach.

    Science.gov (United States)

    Wadle, S; Lehnert, M; Rubenwolf, S; Zengerle, R; von Stetten, F

    2016-03-01

    Primer and probe sequence designs are among the most critical input factors in real-time polymerase chain reaction (PCR) assay optimization. In this study, we present the use of statistical design of experiments (DOE) approach as a general guideline for probe optimization and more specifically focus on design optimization of label-free hydrolysis probes that are designated as mediator probes (MPs), which are used in reverse transcription MP PCR (RT-MP PCR). The effect of three input factors on assay performance was investigated: distance between primer and mediator probe cleavage site; dimer stability of MP and target sequence (influenza B virus); and dimer stability of the mediator and universal reporter (UR). The results indicated that the latter dimer stability had the greatest influence on assay performance, with RT-MP PCR efficiency increased by up to 10% with changes to this input factor. With an optimal design configuration, a detection limit of 3-14 target copies/10 μl reaction could be achieved. This improved detection limit was confirmed for another UR design and for a second target sequence, human metapneumovirus, with 7-11 copies/10 μl reaction detected in an optimum case. The DOE approach for improving oligonucleotide designs for real-time PCR not only produces excellent results but may also reduce the number of experiments that need to be performed, thus reducing costs and experimental times.

  6. A Regional Time-of-Use Electricity Price Based Optimal Charging Strategy for Electrical Vehicles

    Directory of Open Access Journals (Sweden)

    Jun Yang

    2016-08-01

    Full Text Available With the popularization of electric vehicles (EVs, the out-of-order charging behaviors of large numbers of EVs will bring new challenges to the safe and economic operation of power systems. This paper studies an optimal charging strategy for EVs. For that a typical urban zone is divided into four regions, a regional time-of-use (RTOU electricity price model is proposed to guide EVs when and where to charge considering spatial and temporal characteristics. In light of the elastic coefficient, the user response to the RTOU electricity price is analyzed, and also a bilayer optimization charging strategy including regional-layer and node-layer models is suggested to schedule the EVs. On the one hand, the regional layer model is designed to coordinate the EVs located in different time and space. On the other hand, the node layer model is built to schedule the EVs to charge in certain nodes. According to the simulations of an IEEE 33-bus distribution network, the performance of the proposed optimal charging strategy is verified. The results demonstrate that the proposed bilayer optimization strategy can effectively decrease the charging cost of users, mitigate the peak-valley load difference and the network loss. Besides, the RTOU electricity price shows better performance than the time-of-use (TOU electricity price.

  7. Time optimization of (90)Sr measurements: Sequential measurement of multiple samples during ingrowth of (90)Y.

    Science.gov (United States)

    Holmgren, Stina; Tovedal, Annika; Björnham, Oscar; Ramebäck, Henrik

    2016-04-01

    The aim of this paper is to contribute to a more rapid determination of a series of samples containing (90)Sr by making the Cherenkov measurement of the daughter nuclide (90)Y more time efficient. There are many instances when an optimization of the measurement method might be favorable, such as; situations requiring rapid results in order to make urgent decisions or, on the other hand, to maximize the throughput of samples in a limited available time span. In order to minimize the total analysis time, a mathematical model was developed which calculates the time of ingrowth as well as individual measurement times for n samples in a series. This work is focused on the measurement of (90)Y during ingrowth, after an initial chemical separation of strontium, in which it is assumed that no other radioactive strontium isotopes are present. By using a fixed minimum detectable activity (MDA) and iterating the measurement time for each consecutive sample the total analysis time will be less, compared to using the same measurement time for all samples. It was found that by optimization, the total analysis time for 10 samples can be decreased greatly, from 21h to 6.5h, when assuming a MDA of 1Bq/L and at a background count rate of approximately 0.8cpm.

  8. A 75 ps rms time resolution BiCMOS time to digital converter optimized for high rate imaging detectors

    CERN Document Server

    Hervé, C

    2002-01-01

    This paper presents an integrated time to digital converter (TDC) with a bin size adjustable in the range of 125 to 175 ps and a differential nonlinearity of +-0.3%. The TDC has four channels. Its architecture has been optimized for the readout of imaging detectors in use at Synchrotron Radiation facilities. In particular, a built-in logic flags piled-up events. Multi-hit patterns are also supported for other applications. Time measurements are extracted off chip at the maximum throughput of 40 MHz. The dynamic range is 14 bits. It has been fabricated in 0.8 mu m BiCMOS technology. Time critical inputs are PECL compatible whereas other signals are CMOS compatible. A second application specific integrated circuit (ASIC) has been developed which translates NIM electrical levels to PECL ones. Both circuits are used to assemble board level TDCs complying with industry standards like VME, NIM and PCI.

  9. Dynamic Planar Convex Hull with Optimal Query Time and O(log n · log log n ) Update Time

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Jakob, Riko

    2000-01-01

    The dynamic maintenance of the convex hull of a set of points in the plane is one of the most important problems in computational geometry. We present a data structure supporting point insertions in amortized O(log n · log log log n) time, point deletions in amortized O(log n · log log n) time......, and various queries about the convex hull in optimal O(log n) worst-case time. The data structure requires O(n) space. Applications of the new dynamic convex hull data structure are improved deterministic algorithms for the k-level problem and the red-blue segment intersection problem where all red and all...

  10. A strategy for reducing turnaround time in design optimization using a distributed computer system

    Science.gov (United States)

    Young, Katherine C.; Padula, Sharon L.; Rogers, James L.

    1988-01-01

    There is a need to explore methods for reducing lengthly computer turnaround or clock time associated with engineering design problems. Different strategies can be employed to reduce this turnaround time. One strategy is to run validated analysis software on a network of existing smaller computers so that portions of the computation can be done in parallel. This paper focuses on the implementation of this method using two types of problems. The first type is a traditional structural design optimization problem, which is characterized by a simple data flow and a complicated analysis. The second type of problem uses an existing computer program designed to study multilevel optimization techniques. This problem is characterized by complicated data flow and a simple analysis. The paper shows that distributed computing can be a viable means for reducing computational turnaround time for engineering design problems that lend themselves to decomposition. Parallel computing can be accomplished with a minimal cost in terms of hardware and software.

  11. Approximate design of optimal tracking controller for time-delay systems

    Institute of Scientific and Technical Information of China (English)

    TANG Gongyou; LI Chao; ZHAO Yandong

    2006-01-01

    Successive approximate design of the optimal tracking controller for linear systems with time-delay is developed. By applying the successive approximation theory of differential equations, the two-point boundary value (TPBV) problem with both time-delay and time-advance terms derived from the original optimal tracking control (OTC) problem is transformed into a sequence of linear TPBV problems without delay and advance terms. The solution sequence of the linear TPBV problems uniformly converges to the solution of the original OTC problem. The obtained OTC law consists of analytic state feedback terms and a compensation term which is the limit of the adjoint vector sequence. The compensation term can be obtained from an iteration formula of adjoint vectors. By using a finite term of the adjoint vector sequence, a suboptimal tracking control law is revealed. Numerical examples show the effectiveness of the algorithm.

  12. Predicting optimal back-shock times in ultrafiltration hollow fibre modules through path-lines

    DEFF Research Database (Denmark)

    Vinther, Frank; Pinelo, Manuel; Brøns, Morten;

    2014-01-01

    This paper presents a two dimensional mathematical model of back-shocking in ultrafiltration. The model investigates the effect of back-shocking on concentration polarization. The model shows a positive effect on both the volumetric flux and the observed rejection when back-shocking is applied as...... compared to the steady-state solution. Furthermore, the effect of changing different parameters such as inlet velocity, forward and backwards pressure on the back-shock time, the increase in volumetric flux and observed rejection, is presented. Moreover, two analytical estimates for the optimal back-shock...... time derived from calculating the path-lines during a back-shock cycle are presented. Both of these expressions are in good agreement with the results obtained from the mathematical model and data collected from the literature. Based on this, a simple expression for an optimal back-shock time in a...

  13. Analytical and Learning-Based Spectrum Sensing Time Optimization in Cognitive Radio Systems

    CERN Document Server

    Ghadikolaei, Hossein Shokri; Nasiri-Kenari, Masoumeh

    2011-01-01

    Powerful spectrum sensing schemes enable cognitive radios (CRs) to find transmission opportunities in spectral resources allocated exclusively to the primary users. In this paper, maximizing the average throughput of a secondary user by optimizing its spectrum sensing time is formulated assuming that a prior knowledge of the presence and absence probabilities of the primary users is available. The energy consumed for finding a transmission opportunity is evaluated and a discussion on the impact of the number of the primary users on the secondary user throughput and consumed energy is presented. In order to avoid the challenges associated with the analytical method, as a second solution, a systematic neural network-based sensing time optimization approach is also proposed in this paper. The proposed adaptive scheme is able to find the optimum value of the channel sensing time without any prior knowledge or assumption about the wireless environment. The structure, performance, and cooperation of the artificial ...

  14. Multi-objective Optimization For The Dynamic Multi-Pickup and Delivery Problem with Time Windows

    CERN Document Server

    Dridi, Imen Harbaoui; Borne, Pierre; Ksouri, Mekki

    2011-01-01

    The PDPTW is an optimization vehicles routing problem which must meet requests for transport between suppliers and customers satisfying precedence, capacity and time constraints. We present, in this paper, a genetic algorithm for multi-objective optimization of a dynamic multi pickup and delivery problem with time windows (Dynamic m-PDPTW). We propose a brief literature review of the PDPTW, present our approach based on Pareto dominance method and lower bounds, to give a satisfying solution to the Dynamic m-PDPTW minimizing the compromise between total travel cost and total tardiness time. Computational results indicate that the proposed algorithm gives good results with a total tardiness equal to zero with a tolerable cost.

  15. Optimizing the acquisition time profile for a planar integral measurement system with a spinning slat collimator

    International Nuclear Information System (INIS)

    This article considers a hypothetical imaging device with a spinning slat collimator that measures parallel-planar-integral data from an object. This device rotates around the object 180 deg. and stops at N positions uniformly distributed over this 180 deg. . At each stop, the device spins on its own axis 180 deg. and acquires measurements at M positions uniformly distributed over this 180 deg. . For a fixed total imaging time, an optimal distribution of the scanning time among the data measurement locations is searched by a nonlinear programming method: Nelder-Mead's simplex method. The optimal dwell time is approximately proportional to the weighting factor in the backprojector of the reconstruction algorithm. By using an optimal dwell-time profile, the reconstruction signal-to-noise ratio has a gain of 23%-24% for the filtered backprojection algorithm and a gain of 10%-18% for the iterative algorithms, compared with the situation when a constant dwell-time profile is used

  16. Power and time slot allocation in cognitive relay networks using particle swarm optimization.

    Science.gov (United States)

    Derakhshan-Barjoei, Pouya; Dadashzadeh, Gholamreza; Razzazi, Farbod; Razavizadeh, S Mohammad

    2013-01-01

    The two main problems in cognitive radio networks are power and time slot allocation problems which require a precise analysis and guarantee the quality of service in both the primary and secondary users. In this paper, these two problems are considered and a method is proposed to solve the resulting optimization problem. Our proposed method provides an improved performance in solving the constrained nonlinear multiobject optimization for the power control and beamforming in order to reach the maximum capacity and proper adaption of time slots, and as a result a new scheme for joint power and time slot allocation in cognitive relay networks is proposed. We adopt space diversity access as the secondary users access scheme and divide the time between multiple secondary users according to their contribution to primary user's transmission. Helping primary users provides more opportunities for secondary users to access the channel since the primary users can release the channel sooner. In contrast, primary network leases portion of channel access time to the secondary users for their transmission using particle swarm optimization (PSO). Numerical studies show good performance of the proposed scheme with a dynamic cost function in a nonstationary environment.

  17. On the non-stationarity of financial time series: impact on optimal portfolio selection

    Science.gov (United States)

    Livan, Giacomo; Inoue, Jun-ichi; Scalas, Enrico

    2012-07-01

    We investigate the possible drawbacks of employing the standard Pearson estimator to measure correlation coefficients between financial stocks in the presence of non-stationary behavior, and we provide empirical evidence against the well-established common knowledge that using longer price time series provides better, more accurate, correlation estimates. Then, we investigate the possible consequences of instabilities in empirical correlation coefficient measurements on optimal portfolio selection. We rely on previously published works which provide a framework allowing us to take into account possible risk underestimations due to the non-optimality of the portfolio weights being used in order to distinguish such non-optimality effects from risk underestimations genuinely due to non-stationarities. We interpret such results in terms of instabilities in some spectral properties of portfolio correlation matrices.

  18. Reinforcement learning for adaptive optimal control of unknown continuous-time nonlinear systems with input constraints

    Science.gov (United States)

    Yang, Xiong; Liu, Derong; Wang, Ding

    2014-03-01

    In this paper, an adaptive reinforcement learning-based solution is developed for the infinite-horizon optimal control problem of constrained-input continuous-time nonlinear systems in the presence of nonlinearities with unknown structures. Two different types of neural networks (NNs) are employed to approximate the Hamilton-Jacobi-Bellman equation. That is, an recurrent NN is constructed to identify the unknown dynamical system, and two feedforward NNs are used as the actor and the critic to approximate the optimal control and the optimal cost, respectively. Based on this framework, the action NN and the critic NN are tuned simultaneously, without the requirement for the knowledge of system drift dynamics. Moreover, by using Lyapunov's direct method, the weights of the action NN and the critic NN are guaranteed to be uniformly ultimately bounded, while keeping the closed-loop system stable. To demonstrate the effectiveness of the present approach, simulation results are illustrated.

  19. OPTIMAL ANTENNA SUBSET SELECTION AND BLIND DETECTION APPROACH APPLIED TO ORTHOGONAL SPACE-TIME BLOCK CODING

    Institute of Scientific and Technical Information of China (English)

    Xu Hongji; Liu Ju; Gu Bo

    2007-01-01

    An approach combining optimal antenna subset selection with blind detection scheme for Orthogonal Space-Time Block Coding (OSTBC) is proposed in this paper. The optimal antenna subset selection is taken into account at transmitter and/or receiver sides, which chooses the optimal antennas to increase the diversity order of OSTBC and improve further its performance. In order to enhance the robustness of the detection used in the conventional OSTBC scheme, a blind detection scheme based on Independent Component Analysis (ICA) is exploited which can directly extract transmitted signals without channel estimation. Performance analysis shows that the proposed approach can achieve the full diversity and the flexibility of system design by using the antenna selection and the ICA based blind detection schemes.

  20. Particle swarm optimization and its application in MEG source localization using single time sliced data

    Science.gov (United States)

    Lin, Juan; Liu, Chenglian; Guo, Yongning

    2014-10-01

    The estimation of neural active sources from the magnetoencephalography (MEG) data is a very critical issue for both clinical neurology and brain functions research. A widely accepted source-modeling technique for MEG involves calculating a set of equivalent current dipoles (ECDs). Depth in the brain is one of difficulties in MEG source localization. Particle swarm optimization(PSO) is widely used to solve various optimization problems. In this paper we discuss its ability and robustness to find the global optimum in different depths of the brain when using single equivalent current dipole (sECD) model and single time sliced data. The results show that PSO is an effective global optimization to MEG source localization when given one dipole in different depths.

  1. Optimization of vortex pinning by nanoparticles using simulations of time-dependent Ginzburg-Landau model.

    Energy Technology Data Exchange (ETDEWEB)

    Koshelev, A. E.; Sadovskyy, I. A.; Phillips, C. L.; Glatz, A.

    2016-02-29

    Introducing nanoparticles into superconducting materials has emerged as an efficient route to enhance their current-carrying capability. We address the problem of optimizing vortex pinning landscape for randomly distributed metallic spherical inclusions using large-scale numerical simulations of time- dependent Ginzburg-Landau equations. We found the size and density of particles for which the highest critical current is realized in a fixed magnetic field. For each particle size and magnetic field, the critical current reaches a maximum value at a certain particle density, which typically corresponds to 15{23% of the total volume being replaced by nonsuperconducting material. For fixed diameter, this optimal particle density increases with the magnetic field. Moreover, we found that the optimal particle diameter slowly decreases with the magnetic field from 4.5 to 2.5 coherence lengths at a given temperature. This result shows that pinning landscapes have to be designed for specific applications taking into account relevant magnetic field scales.

  2. Real-time motion-adaptive-optimization (MAO) in TomoTherapy

    Science.gov (United States)

    Lu, Weiguo; Chen, Mingli; Ruchala, Kenneth J.; Chen, Quan; Langen, Katja M.; Kupelian, Patrick A.; Olivera, Gustavo H.

    2009-07-01

    IMRT delivery follows a planned leaf sequence, which is optimized before treatment delivery. However, it is hard to model real-time variations, such as respiration, in the planning procedure. In this paper, we propose a negative feedback system of IMRT delivery that incorporates real-time optimization to account for intra-fraction motion. Specifically, we developed a feasible workflow of real-time motion-adaptive-optimization (MAO) for TomoTherapy delivery. TomoTherapy delivery is characterized by thousands of projections with a fast projection rate and ultra-fast binary leaf motion. The technique of MAO-guided delivery calculates (i) the motion-encoded dose that has been delivered up to any given projection during the delivery and (ii) the future dose that will be delivered based on the estimated motion probability and future fluence map. These two pieces of information are then used to optimize the leaf open time of the upcoming projection right before its delivery. It consists of several real-time procedures, including 'motion detection and prediction', 'delivered dose accumulation', 'future dose estimation' and 'projection optimization'. Real-time MAO requires that all procedures are executed in time less than the duration of a projection. We implemented and tested this technique using a TomoTherapy® research system. The MAO calculation took about 100 ms per projection. We calculated and compared MAO-guided delivery with two other types of delivery, motion-without-compensation delivery (MD) and static delivery (SD), using simulated 1D cases, real TomoTherapy plans and the motion traces from clinical lung and prostate patients. The results showed that the proposed technique effectively compensated for motion errors of all test cases. Dose distributions and DVHs of MAO-guided delivery approached those of SD, for regular and irregular respiration with a peak-to-peak amplitude of 3 cm, and for medium and large prostate motions. The results conceptually proved that

  3. Checklist for the crop weeds of Paraguay

    Directory of Open Access Journals (Sweden)

    Juana De Egea

    2016-10-01

    Full Text Available Paraguay, a country whose economy is based mainly on agriculture and livestock for export, has experienced a major expansion in mechanized crops during the last few decades. Despite being heavily dependent on agriculture, Paraguay has very limited research on crop weeds, in spite of these having a high economic impact on production. This work aims to update and enhance the knowledgebase on the most common weeds affecting productive fields throughout the different ecoregions of Paraguay. We present here the first checklist of crop weeds for the country, which includes a total of 256 taxa (189 species, 10 subspecies, 54 varieties and 3 forms, with the most species-rich families being Poaceae and Asteraceae followed by Malvaceae, Amaranthaceae, Fabaceae and Solanaceae. The list includes three new records for the country. Synonyms, distribution details within Paraguay, habit and a voucher specimen are provided for each taxon.

  4. Araneae Sloveniae: a national spider species checklist

    Directory of Open Access Journals (Sweden)

    Rok Kostanjšek

    2015-01-01

    Full Text Available The research of the spider fauna of Slovenia dates back to the very beginning of binomial nomenclature, and has gone through more and less prolific phases with authors concentrating on taxonomy, faunistics, ecology and zoogeographic reviews. Although the body of published works is remarkable for a small nation, the faunistic data has remained too scattered for a thorough understanding of regional biotic diversity, for comparative and ecological research, and for informed conservation purposes. A national checklist is long overdue. Here, a critical review of all published records in any language is provided. The species list currently comprises 738 species, is published online at http://www.bioportal.si/katalog/araneae.php under the title Araneae Sloveniae, and will be updated in due course. This tool will fill the void in cataloguing regional spider faunas and will facilitate further araneological research in central and southern Europe.

  5. A novel trajectory prediction control for proximate time-optimal digital control DC—DC converters

    Science.gov (United States)

    Qing, Wang; Ning, Chen; Shen, Xu; Weifeng, Sun; Longxing, Shi

    2014-09-01

    The purpose of this paper is to present a novel trajectory prediction method for proximate time-optimal digital control DC—DC converters. The control method provides pre-estimations of the duty ratio in the next several switching cycles, so as to compensate the computational time delay of the control loop and increase the control loop bandwidth, thereby improving the response speed. The experiment results show that the fastest transient response time of the digital DC—DC with the proposed prediction is about 8 μs when the load current changes from 0.6 to 0.1 A.

  6. Real-time simulation requirements for study and optimization of power system controls

    Energy Technology Data Exchange (ETDEWEB)

    Nakra, Harbans; McCallum, David; Gagnon, Charles [Institut de Recherche d`Hydro-Quebec, Quebec, PQ (Canada); Venne, Andre; Gagnon, Julien [Hydro-Quebec, Montreal, PQ (Canada)

    1994-12-31

    At the time of ordering for the multi-terminal dc system linking Hydro-Quebec with New England, Hydro-Quebec also ordered functionally duplicate controls of all the converters and installed these in its real time simulation laboratory. The Hydro-Quebec ac system was also simulated in detail and the testing of the controls as thus made possible in a realistic environment. Many field tests were duplicated and many additional tests were done for correction and optimization. This paper describes some of the features of the real-time simulation carried out for this purpose. (author) 3 figs.

  7. Memetic Approaches for Optimizing Hidden Markov Models: A Case Study in Time Series Prediction

    Science.gov (United States)

    Bui, Lam Thu; Barlow, Michael

    We propose a methodology for employing memetics (local search) within the framework of evolutionary algorithms to optimize parameters of hidden markov models. With this proposal, the rate and frequency of using local search are automatically changed over time either at a population or individual level. At the population level, we allow the rate of using local search to decay over time to zero (at the final generation). At the individual level, each individual is equipped with information of when it will do local search and for how long. This information evolves over time alongside the main elements of the chromosome representing the individual.

  8. Online adaptive optimal control for continuous-time nonlinear systems with completely unknown dynamics

    Science.gov (United States)

    Lv, Yongfeng; Na, Jing; Yang, Qinmin; Wu, Xing; Guo, Yu

    2016-01-01

    An online adaptive optimal control is proposed for continuous-time nonlinear systems with completely unknown dynamics, which is achieved by developing a novel identifier-critic-based approximate dynamic programming algorithm with a dual neural network (NN) approximation structure. First, an adaptive NN identifier is designed to obviate the requirement of complete knowledge of system dynamics, and a critic NN is employed to approximate the optimal value function. Then, the optimal control law is computed based on the information from the identifier NN and the critic NN, so that the actor NN is not needed. In particular, a novel adaptive law design method with the parameter estimation error is proposed to online update the weights of both identifier NN and critic NN simultaneously, which converge to small neighbourhoods around their ideal values. The closed-loop system stability and the convergence to small vicinity around the optimal solution are all proved by means of the Lyapunov theory. The proposed adaptation algorithm is also improved to achieve finite-time convergence of the NN weights. Finally, simulation results are provided to exemplify the efficacy of the proposed methods.

  9. Applications of an alternative formulation for one-layer real time optimization

    Directory of Open Access Journals (Sweden)

    Schiavon Júnior A.L.

    2000-01-01

    Full Text Available This paper presents two applications of an alternative formulation for one-layer real time structure for control and optimization. This new formulation have arisen from predictive controller QDMC (Quadratic Dynamic Matrix Control, a type of predictive control (Model Predictive Control - MPC. At each sampling time, the values of the outputs of process are fed into the optimization-control structure which supplies the new values of the manipulated variables already considering the best conditions of process. The variables of optimization are both set-point changes and control actions. The future stationary outputs and the future stationary control actions have both a different formulation of conventional one-layer structure and they are calculated from the inverse gain matrix of the process. This alternative formulation generates a convex problem, which can be solved by less sophisticated optimization algorithms. Linear and nonlinear economic objective functions were considered. The proposed approach was applied to two linear models, one SISO (single-input/single output and the other MIMO (multiple-input/multiple-output. The results showed an excellent performance.

  10. Digital redesign of uncertain interval systems based on time-response resemblance via particle swarm optimization.

    Science.gov (United States)

    Hsu, Chen-Chien; Lin, Geng-Yu

    2009-07-01

    In this paper, a particle swarm optimization (PSO) based approach is proposed to derive an optimal digital controller for redesigned digital systems having an interval plant based on time-response resemblance of the closed-loop systems. Because of difficulties in obtaining time-response envelopes for interval systems, the design problem is formulated as an optimization problem of a cost function in terms of aggregated deviation between the step responses corresponding to extremal energies of the redesigned digital system and those of their continuous counterpart. A proposed evolutionary framework incorporating three PSOs is subsequently presented to minimize the cost function to derive an optimal set of parameters for the digital controller, so that step response sequences corresponding to the extremal sequence energy of the redesigned digital system suitably approximate those of their continuous counterpart under the perturbation of the uncertain plant parameters. Computer simulations have shown that redesigned digital systems incorporating the PSO-derived digital controllers have better system performance than those using conventional open-loop discretization methods.

  11. Optimized quantum sensing with a single electron spin using real-time adaptive measurements.

    Science.gov (United States)

    Bonato, C; Blok, M S; Dinani, H T; Berry, D W; Markham, M L; Twitchen, D J; Hanson, R

    2016-03-01

    Quantum sensors based on single solid-state spins promise a unique combination of sensitivity and spatial resolution. The key challenge in sensing is to achieve minimum estimation uncertainty within a given time and with high dynamic range. Adaptive strategies have been proposed to achieve optimal performance, but their implementation in solid-state systems has been hindered by the demanding experimental requirements. Here, we realize adaptive d.c. sensing by combining single-shot readout of an electron spin in diamond with fast feedback. By adapting the spin readout basis in real time based on previous outcomes, we demonstrate a sensitivity in Ramsey interferometry surpassing the standard measurement limit. Furthermore, we find by simulations and experiments that adaptive protocols offer a distinctive advantage over the best known non-adaptive protocols when overhead and limited estimation time are taken into account. Using an optimized adaptive protocol we achieve a magnetic field sensitivity of 6.1 ± 1.7 nT Hz(-1/2) over a wide range of 1.78 mT. These results open up a new class of experiments for solid-state sensors in which real-time knowledge of the measurement history is exploited to obtain optimal performance.

  12. Time-optimal path planning in dynamic flows using level set equations: theory and schemes

    Science.gov (United States)

    Lolla, Tapovan; Lermusiaux, Pierre F. J.; Ueckermann, Mattheus P.; Haley, Patrick J.

    2014-10-01

    We develop an accurate partial differential equation-based methodology that predicts the time-optimal paths of autonomous vehicles navigating in any continuous, strong, and dynamic ocean currents, obviating the need for heuristics. The goal is to predict a sequence of steering directions so that vehicles can best utilize or avoid currents to minimize their travel time. Inspired by the level set method, we derive and demonstrate that a modified level set equation governs the time-optimal path in any continuous flow. We show that our algorithm is computationally efficient and apply it to a number of experiments. First, we validate our approach through a simple benchmark application in a Rankine vortex flow for which an analytical solution is available. Next, we apply our methodology to more complex, simulated flow fields such as unsteady double-gyre flows driven by wind stress and flows behind a circular island. These examples show that time-optimal paths for multiple vehicles can be planned even in the presence of complex flows in domains with obstacles. Finally, we present and support through illustrations several remarks that describe specific features of our methodology.

  13. Optimal post-warranty maintenance policy with repair time threshold for minimal repair

    International Nuclear Information System (INIS)

    In this paper, we consider a renewable minimal repair–replacement warranty policy and propose an optimal maintenance model after the warranty is expired. Such model adopts the repair time threshold during the warranty period and follows with a certain type of system maintenance policy during the post-warranty period. As for the criteria for optimality, we utilize the expected cost rate per unit time during the life cycle of the system, which has been frequently used in many existing maintenance models. Based on the cost structure defined for each failure of the system, we formulate the expected cost rate during the life cycle of the system, assuming that a renewable minimal repair–replacement warranty policy with the repair time threshold is provided to the user during the warranty period. Once the warranty is expired, the maintenance of the system is the user's sole responsibility. The life cycle of the system is defined on the perspective of the user and the expected cost rate per unit time is derived in this context. We obtain the optimal maintenance policy during the maintenance period following the expiration of the warranty period by minimizing such a cost rate. Numerical examples using actual failure data are presented to exemplify the applicability of the methodologies proposed in this paper.

  14. Time Intervals for Maintenance of Offshore Structures Based on Multiobjective Optimization

    Directory of Open Access Journals (Sweden)

    Dante Tolentino

    2013-01-01

    Full Text Available With the aim of establishing adequate time intervals for maintenance of offshore structures, an approach based on multiobjective optimization for making decisions is proposed. The formulation takes into account the degradation of the mechanical properties of the structures and its influence over time on both the structural capacity and the structural demand, given a maximum wave height. The set of time intervals for maintenance corresponds to a balance between three objectives: (a structural reliability, (b damage index, and (c expected cumulative total cost. Structural reliability is expressed in terms of confidence factors as functions of time by means of closed-form mathematical expressions which consider structural deterioration. The multiobjective optimization is solved using an evolutionary genetic algorithm. The approach is applied to an offshore platform located at Campeche Bay in the Gulf of Mexico. The optimization criterion includes the reconstruction of the platform. Results indicate that if the first maintenance action is made in 5 years after installing the structure, the second repair action should be made in the following 7 to 10 years; however, if the first maintenance action is made in 6 years after installing the structure, then the second should be made in the following 5 to 8 years.

  15. Joint optimization of LORA and spares stocks considering corrective maintenance time

    Institute of Scientific and Technical Information of China (English)

    Linhan Guo; Jiujiu Fan; Meilin Wen; Rui Kang

    2015-01-01

    Level of repair analysis (LORA) is an important method of maintenance decision for establishing systems of operation and maintenance in the equipment development period. Currently, the research on equipment of repair level focuses on economic analy-sis models which are used to optimize costs and rarely considers the maintenance time required by the implementation of the main-tenance program. In fact, as to the system requiring high mission complete success, the maintenance time is an important factor which has a great influence on the availability of equipment sys-tems. Considering the relationship between the maintenance time and the spares stocks level, it is obvious that there are contra-dictions between the maintenance time and the cost. In order to balance these two factors, it is necessary to build an optimization LORA model. To this end, the maintenance time representing per-formance characteristic is introduced, and on the basis of spares stocks which is traditional y regarded as a decision variable, a de-cision variable of repair level is added, and a multi-echelon multi-indenture (MEMI) optimization LORA model is built which takes the best cost-effectiveness ratio as the criterion, the expected num-ber of backorder (EBO) as the objective function and the cost as the constraint. Besides, the paper designs a convex programming algorithm of multi-variable for the optimization model, provides solutions to the non-convex objective function and methods for improving the efficiency of the algorithm. The method provided in this paper is proved to be credible and effective according to the numerical example and the simulation result.

  16. A multi-step standard-cell placement algorithm of optimizing timing and congestion behavior

    Institute of Scientific and Technical Information of China (English)

    侯文婷; 洪先龙; 吴为民; 蔡懿慈

    2002-01-01

    The timing behavior and congestion behavior are two important goals in the performance-driven standard-cell placement. In this paper, we analyze the relationship between the timing and congestion behavior. We bring up a multi-step placement algorithm to reach the two goals. First, the timing-driven placement algorithm is used to find the global optimal solution. In the second step, the algorithm tries to decrease the maximum congestion while not deteriorating the timing behavior. We have implemented our algorithm and tested it with real circuits. The results show that the maximum delay can decrease by 30% in our timing-driven placement and in the second step the maximum congestion will decrease by 10% while the timing behavior is unchanged.

  17. Optimal timing of CO{sub 2} mitigation costs; Optimales Timing von CO{sub 2}-Vermeidungskosten

    Energy Technology Data Exchange (ETDEWEB)

    Schleich, J. [Fraunhofer-Institut fuer Systemtechnik und Innovationsforschung (ISI), Karlsruhe (Germany). Abt. Energietechnik und Energiepolitik

    1999-07-01

    The lecture refers to and summarizes the essence of available publications by experts worldwide, dealing with carbon dioxide mitigation policy and major aspects of global implementation such as: Time-related distribution of greenhouse gas reduction costs, the modelling of optimal carbon dioxide mitigation strategies, and the optimal time path. Various approaches of a variety of authors mentioned in the bibliography are briefly discussed, as well as case studies and models. (orig./CB) [German] Die zeitliche Verteilung der Treibhausgasminderungskosten steht im Mittelpunkt der aktuellen politischen und oekonomischen Debatte um die Ausgestaltung von optimalen CO{sub 2}-Reduktionsstrategien (Jochem 1998). Kernpunkt ist die Frage nach dem optimalen Zeitpfad, d.h. wann CO{sub 2}-Reduktionen vorgenommen werden sollen. Wenngleich die Existenz des Treibhausgaseffektes per se nicht in Frage gestellt wird, so kommen mehrere Studien zu dem Schluss, dass es aus oekonomischer Sicht sinnvoll, ist, Verminderungaktivitaeten zunaechst auf die Zukunft zu verschieben und dann spaeter entsprechend staerker zu vermeiden. Diese abwartende Strategie, die zur Zeit auch von der US-Regierung favorisiert wird, findet in der Literatur Zuspruch von Nordhaus (1994), Manne, Mendelson und Richels (1995), Peck und Teisberg (1993), und Wigley, Richels, und Edmonds (1996). Am bekanntesten sind wohl die Ergebnisse des von Nordhaus (1994) entwickelten DICE Models, wonach es optimal ist, die CO{sub 2}-Emissionsrate ueber die naechsten hundert Jahre zunaechst zu verdreifachen. Eine entgegengesetzte Position vertreten Cline (1992), Azar und Sterner (1996), Schultz und Kastings (1997) sowie Hasselman et al. (1997), die - ebenso wie mehrere EU Laender (z.B. Deutschland, DK) - eine Strategie mit fruehzeitigen Emissionsreduktionen befuerworten. (orig.)

  18. Human factors engineering checklists for application in the SAR process

    Energy Technology Data Exchange (ETDEWEB)

    Overlin, T.K.; Romero, H.A.; Ryan, T.G.

    1995-03-01

    This technical report was produced to assist the preparers and reviewers of the human factors portions of the SAR in completing their assigned tasks regarding analysis and/or review of completed analyses. The checklists, which are the main body of the report, and the subsequent tables, were developed to assist analysts in generating the needed analysis data to complete the human engineering analysis for the SAR. The technical report provides a series of 19 human factors engineering (HFE) checklists which support the safety analyses of the US Department of Energy`s (DOE) reactor and nonreactor facilities and activities. The results generated using these checklists and in the preparation of the concluding analyses provide the technical basis for preparing the human factors chapter, and subsequent inputs to other chapters, required by DOE as a part of the safety analysis reports (SARs). This document is divided into four main sections. The first part explains the origin of the checklists, the sources utilized, and other information pertaining to the purpose and scope of the report. The second part, subdivided into 19 sections, is the checklists themselves. The third section is the glossary which defines terms that could either be unfamiliar or have specific meanings within the context of these checklists. The final section is the subject index in which the glossary terms are referenced back to the specific checklist and page the term is encountered.

  19. An Autopsy Checklist: A Monitor of Safety and Risk Management.

    Science.gov (United States)

    Shkrum, Michael James; Kent, Jessica

    2016-09-01

    Any autopsy has safety and risk management issues, which can arise in the preautopsy, autopsy, and postautopsy phases. The London Health Sciences Department of Pathology and Laboratory Medicine Autopsy Checklist was developed to address these issues. The current study assessed 1 measure of autopsy safety: the effectiveness of the checklist in documenting pathologists' communication of the actual or potential risk of blood-borne infections to support staff. Autopsy checklists for cases done in 2012 and 2013 were reviewed. The frequency of communication, as recorded in checklists, by pathologists to staff of previously diagnosed blood-borne infections (hepatitis B/C and human immunodeficiency virus) or the risk of infection based on lifestyle (eg, intravenous drug abuse) was tabulated. These data were compared with medical histories of the deceased and circumstances of their deaths described in the final autopsy reports. Information about blood-borne infections was recorded less frequently in the checklists compared with the final reports. Of 4 known human immunodeficiency virus cases, there was no checklist documentation in 3. All 11 hand injuries were documented. None of these cases had known infectious risks. The Autopsy Checklist is a standardized means of documenting safety and risk issues arising during the autopsy process, but its effectiveness relies on accurate completion. PMID:27356015

  20. Human factors engineering checklists for application in the SAR process

    International Nuclear Information System (INIS)

    This technical report was produced to assist the preparers and reviewers of the human factors portions of the SAR in completing their assigned tasks regarding analysis and/or review of completed analyses. The checklists, which are the main body of the report, and the subsequent tables, were developed to assist analysts in generating the needed analysis data to complete the human engineering analysis for the SAR. The technical report provides a series of 19 human factors engineering (HFE) checklists which support the safety analyses of the US Department of Energy's (DOE) reactor and nonreactor facilities and activities. The results generated using these checklists and in the preparation of the concluding analyses provide the technical basis for preparing the human factors chapter, and subsequent inputs to other chapters, required by DOE as a part of the safety analysis reports (SARs). This document is divided into four main sections. The first part explains the origin of the checklists, the sources utilized, and other information pertaining to the purpose and scope of the report. The second part, subdivided into 19 sections, is the checklists themselves. The third section is the glossary which defines terms that could either be unfamiliar or have specific meanings within the context of these checklists. The final section is the subject index in which the glossary terms are referenced back to the specific checklist and page the term is encountered

  1. Time reversal versus adaptive optimization for spatiotemporal nanolocalization in a random nanoantenna

    Science.gov (United States)

    Differt, Dominik; Hensen, Matthias; Pfeiffer, Walter

    2016-05-01

    Spatiotemporal nanolocalization of ultrashort pulses in a random scattering nanostructure via time reversal and adaptive optimization employing a genetic algorithm and a suitably defined fitness function is studied for two embedded nanoparticles that are separated by only a tenth of the free space wavelength. The nanostructure is composed of resonant core-shell nanoparticles (TiO2 core and Ag shell) placed randomly surrounding these two nanoparticles acting as targets. The time reversal scheme achieves selective nanolocalization only by chance if the incident radiation can couple efficiently to dipolar local modes interacting with the target/emitter particle. Even embedding the structure in a reverberation chamber fails improving the nanolocalization. In contrast, the adaptive optimization strategy reliably yields nanolocalization of the radiation and allows a highly selective excitation of either target position. This demonstrates that random scattering structures are interesting multi-purpose optical nanoantennas to realize highly flexible spatiotemporal optical near-field control.

  2. Series-based approximate approach of optimal tracking control for nonlinear systems with time-delay

    Institute of Scientific and Technical Information of China (English)

    Gongyou Tang; Mingqu Fan

    2008-01-01

    The optimal output tracking control (OTC) problem for nonlinear systems with time-delay is considered.Using a series-based approx-imate approach,the original OTC problem is transformed into iteration solving linear two-point boundary value problems without time-delay.The OTC law obtained consists of analytical linear feedback and feedforward terms and a nonlinear compensation term with an infinite series of the adjoint vectors.By truncating a finite sum of the adjoint vector series,an approximate optimal tracking control law is obtained.A reduced-order reference input observer is constructed to make the feedforward term physically realizable.Simulation exam-pies are used to test the validity of the series-based approximate approach.

  3. Symmetry breaking in optimal timing of traffic signals on an idealized two-way street

    Science.gov (United States)

    Panaggio, Mark J.; Ottino-Löffler, Bertand J.; Hu, Peiguang; Abrams, Daniel M.

    2013-09-01

    Simple physical models based on fluid mechanics have long been used to understand the flow of vehicular traffic on freeways; analytically tractable models of flow on an urban grid, however, have not been as extensively explored. In an ideal world, traffic signals would be timed such that consecutive lights turned green just as vehicles arrived, eliminating the need to stop at each block. Unfortunately, this “green-wave” scenario is generally unworkable due to frustration imposed by competing demands of traffic moving in different directions. Until now this has typically been resolved by numerical simulation and optimization. Here, we develop a theory for the flow in an idealized system consisting of a long two-way road with periodic intersections. We show that optimal signal timing can be understood analytically and that there are counterintuitive asymmetric solutions to this signal coordination problem. We further explore how these theoretical solutions degrade as traffic conditions vary and automotive density increases.

  4. Symmetry breaking in optimal timing of traffic signals on an idealized two-way street

    CERN Document Server

    Panaggio, Mark J; Hu, Peiguang; Abrams, Daniel M

    2013-01-01

    Simple physical models based on fluid mechanics have long been used to understand the flow of vehicular traffic on freeways; analytically tractable models of flow on an urban grid, however, have not been as extensively explored. In an ideal world, traffic signals would be timed such that consecutive lights turned green just as vehicles arrived, eliminating the need to stop at each block. Unfortunately, this "green wave" scenario is generally unworkable due to frustration imposed by competing demands of traffic moving in different directions. Until now this has typically been resolved by numerical simulation and optimization. Here, we develop a theory for the flow in an idealized system consisting of a long two-way road with periodic intersections. We show that optimal signal timing can be understood analytically and that there are counter-intuitive asymmetric solutions to this signal coordination problem. We further explore how these theoretical solutions degrade as traffic conditions vary and automotive dens...

  5. Optimal conservation resource allocation under variable economic and ecological time discounting rates in boreal forest

    DEFF Research Database (Denmark)

    Mazziotta, Adriano; Montesino Pouzols, Federico; Mönkkönen, Mikko;

    2016-01-01

    Resource allocation to multiple alternative conservation actions is a complex task. A common trade-off occurs between protection of smaller, expensive, high-quality areas versus larger, cheaper, partially degraded areas. We investigate optimal allocation into three actions in boreal forest: current...... standard forest management rules, setting aside of mature stands, or setting aside of clear-cuts. We first estimated how habitat availability for focal indicator species and economic returns from timber harvesting develop through time as a function of forest type and action chosen. We then developed...... an optimal resource allocation by accounting for budget size and habitat availability of indicator species in different forest types. We also accounted for the perspective adopted towards sustainability, modeled via temporal preference and economic and ecological time discounting. Controversially, we found...

  6. Controlling the Attitude Maneuvers of Flexible Spacecraft by Using Time-Optimal Shaped Inputs

    Science.gov (United States)

    Parman, S.; Koguchi, H.

    1999-04-01

    A three-dimensional rest-to-rest attitude maneuver of flexible spacecraft equipped with on-off reaction jets is studied. Equations of motion of the spacecraft are developed by using Lagrangian formulation. The finite element method is used to discretize elastic deformations of a particular model of satellite with flexible solar panels by modelling the panels as flat plate structures in bending. Under unshaped inputs, the maneuvers induce an undesirable motion of the satellite as well as vibration of the solar panels. Time-optimal and fuel-efficient input shapers are then applied to reduce the residual oscillation of its motion at several natural frequencies in order to get an expected pointing precision of the satellite. Once the shaped inputs are given to the satellite, the performance improves significantly. Results indicate that, the fuel-efficient shaped inputs give smaller maximum deflections of flexible members compared with the time-optimal ones.

  7. Time-Scale and Noise Optimality in Self-Organized Critical Adaptive Networks

    CERN Document Server

    Kuehn, Christian

    2011-01-01

    Recent studies have shown that adaptive networks driven by simple local rules can organize into "critical" global steady states, thereby providing another framework for self-organized criticality (SOC). Here we study SOC in an adaptive network considered first by Bornholdt and Rohlf [PRL, 84(26), p.6114-6117, 2000]. We focus on the important convergence to criticality and discover time-scale and noise optimal behaviour as well as a noise-induced phase transition. Due to the complexity of adaptive networks dynamics we suggest to investigate each effect separately by developing simple models. These models reveal three generically possible low-dimensional dynamical behaviors: time-scale resonance (TR), a simplified version of stochastic resonance - which call steady state stochastic resonance (SSR) - as well as noise-induced phase transitions. Thereby, our study not only opens up new directions for optimality in SOC but also applies to a much wider class of dynamical systems.

  8. Exploring sensitive dependence and transitivity to optimize travel time in chaotic systems

    International Nuclear Information System (INIS)

    Transitivity and sensitive dependence on initial conditions are the main characteristics of chaotic behavior. The latter one can be exploited so that small controlled perturbations in system parameters may imply a faster transfer in time from a desired start point to a neighborhood of a desired final state. In this study three targeting approaches are evaluated: The first one uses a geometric approach to find the proper perturbation which allows a faster transfer between two desired points; The second, an evolutionary algorithm called GEO (Generalized External Optimization), is adapted to search for optimized orbits; The third one, uses successive perturbations along the path in order to direct the orbits to the final desired point in a short time interval. These three methods are evaluated regarding performance and implementation complexity

  9. System for Road Vehicle Energy Optimization Using Real Time Road and Traffic Information

    Directory of Open Access Journals (Sweden)

    Felipe Jiménez

    2014-06-01

    Full Text Available Nowadays, reducing the energy and fuel consumption of road vehicles is a key issue. Different strategies have been proposed. One of them is to promote Eco-driving behaviour among drivers. Most Eco-driving tips take into account only the road stretch where the vehicle is located. However, larger improvements could be achieved if information from subsequent stretches is used. The main objective of this work is to develop a system to warn the driver in real time of the optimal speed that should be maintained on every road segment in order to optimize the energy used and the fuel consumed while observing a time schedule. The system takes into account the road vertical profile, the fixed and variable speed limits and the traffic information retrieved using V2V and V2I communications. The system has been tested on real road sections with satisfactory results in fuel savings.

  10. Optimization and validation of the method lactose intolerance genotyping with real-time PCR

    OpenAIRE

    Stenberg, Jenny

    2011-01-01

    Abstract Primary lactose intolerance has been associated with a single nucleotide polymorphism located upstream of the lactase gene. The most common diagnostic tests for lactose intolerance are time-consuming and the patient is not allowed to eat and drink for 12 hours before the test is carried out. A method that can establish the genotype would be an easier way of diagnosing lactose intolerance compared to fenotypic lactose intolerance tests. Optimization and validation of a previously pu...

  11. Optimal design of multi-channel microreactor for uniform residence time distribution

    OpenAIRE

    Renault, Cyril; Colin, Stéphane; Orieux, Stéphane; Cognet, Patrick; Tzedakis, Théodore

    2012-01-01

    Multi-channel microreactors can be used for various applications that require chemical or electrochemical reactions in either liquid, gaseous or multi phase. For an optimal control of the chemical reactions, one key parameter for the design of such microreactors is the residence time distribution of the fluid, which should be as uniform as possible in the series of microchannels that make up the core of the reactor. Based on simplifying assumptions, an analytical model is proposed for optimiz...

  12. Move-optimal schedules for parallel machines to minimize total weighted completion time

    OpenAIRE

    Brueggemann, T.; J L Hurink; Kern, W

    2005-01-01

    We study the minimum total weighted completion time problem on identical machines, which is known to be strongly $\\mathcal{NP}$-hard. We analyze a simple local search heuristic, moving jobs from one machine to another. The local optima can be shown to be approximately optimal with approximation ratio $1.5$. In case all jobs have equal Smith ratios, the approximation ratio is at most $1.092$.

  13. On invariant ellipsoids for discrete-time systems by saturated optimal controls

    Institute of Scientific and Technical Information of China (English)

    Bin ZHOU; Guangren DUAN

    2008-01-01

    Analytical approximation of the maximal invariant ellipsoid for discrete-time linear systems with saturated optimal control is established, which is less conservative than existing computationally un-intensive results. Simultaneously, necessary and sufficient conditions for such approximation being equal to the real maximal invariant ellipsoid is presented.All results are given analytically and can easily be implemented in practice.An illustrative example is given to show the effectiveness of the proposed approach.

  14. Convergence results for continuous-time dynamics arising in ant colony optimization

    OpenAIRE

    Bliman, Pierre-Alexandre; Bhaya, Amit; Kaszkurewicz, Eugenius; Jayadeva

    2014-01-01

    This paper studies the asymptotic behavior of several continuous-time dynamical systems which are analogs of ant colony optimization algorithms that solve shortest path problems. Local asymptotic stability of the equilibrium corresponding to the shortest path is shown under mild assumptions. A complete study is given for a recently proposed model called EigenAnt: global asymptotic stability is shown, and the speed of convergence is calculated explicitly and shown to be proportional to the dif...

  15. On the non-stationarity of financial time series: impact on optimal portfolio selection

    OpenAIRE

    Livan, Giacomo; Inoue, Jun-ichi; Scalas, Enrico

    2012-01-01

    We investigate the possible drawbacks of employing the standard Pearson estimator to measure correlation coefficients between financial stocks in the presence of non-stationary behavior, and we provide empirical evidence against the well-established common knowledge that using longer price time series provides better, more accurate, correlation estimates. Then, we investigate the possible consequences of instabilities in empirical correlation coefficient measurements on optimal portfolio sele...

  16. Optimal Application Timing of Pest Control Tactics in Nonautonomous Pest Growth Model

    OpenAIRE

    Shujuan Zhang; Juhua Liang; Sanyi Tang

    2014-01-01

    Considering the effects of the living environment on growth of populations, it is unrealistic to assume that the growth rates of predator and prey are all constants in the models with integrated pest management (IPM) strategies. Therefore, a nonautonomous predator-prey system with impulsive effect is developed and investigated in the present work. In order to determine the optimal application timing of IPM tactics, the threshold value which guarantees the stability of pest-free periodic solut...

  17. Optimization of Data Requests Timing by Working with Matrixes under MSAccess Environment

    Directory of Open Access Journals (Sweden)

    Alexandru ATOMEI

    2010-09-01

    Full Text Available This paper is going to emphasize an optimised code in order to manage matrix calculus under MSAccess. The economic impact of using such a method is the optimal cost-benefit solution, and optimised timing for data management. As well, matrix calculus is the base of Variance-Covariance method used by financial corporations as an advanced method for estimation of market risk movements with direct impact over the capital required by prudential bodies.

  18. Design Optimization of Multi-Cluster Embedded Systems for Real-Time Applications

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo;

    2004-01-01

    We present an approach to design optimization of multi-cluster embedded systems consisting of time-triggered and event-triggered clusters, interconnected via gateways. In this paper, we address design problems which are characteristic to multi-clusters: partitioning of the system functionality...... an efficient utilization of the system. The developed algorithms are evaluated using extensive experiments and a real-life example....

  19. Design Optimization of Multi-Cluster Embedded Systems for Real-Time Applications

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo

    2006-01-01

    We present an approach to design optimization of multi-cluster embedded systems consisting of time-triggered and event-triggered clusters, interconnected via gateways. In this paper, we address design problems which are characteristic to multi-clusters: partitioning of the system functionality...... an efficient utilization of the system. The developed algorithms are evaluated using extensive experiments and a real-life example....

  20. 12 hours after cerebral ischemia is the optimal time for bone marrow mesenchymal stem cell transplantation

    OpenAIRE

    Seyed Mojtaba Hosseini; Mohammad Farahmandnia; Zahra Razi; Somayeh Delavarifar; Benafsheh Shakibajahromi

    2015-01-01

    Cell therapy using stem cell transplantation against cerebral ischemia has been reported. However, it remains controversial regarding the optimal time for cell transplantation and the transplantation route. Rat models of cerebral ischemia were established by occlusion of the middle cerebral artery. At 1, 12 hours, 1, 3, 5 and 7 days after cerebral ischemia, bone marrow mesenchymal stem cells were injected via the tail vein. At 28 days after cerebral ischemia, rat neurological function was eva...

  1. Polynomial-time Construction of Optimal Tree-structured Communication Data Layout Descriptions

    OpenAIRE

    Ganian, Robert; Kalany, Martin; Szeider, Stefan; Träff, Jesper Larsson

    2015-01-01

    We show that the problem of constructing tree-structured descriptions of data layouts that are optimal with respect to space or other criteria from given sequences of displacements, can be solved in polynomial time. The problem is relevant for efficient compiler and library support for communication of noncontiguous data, where tree-structured descriptions with low-degree nodes and small index arrays are beneficial for the communication soft- and hardware. An important example is the Message-...

  2. Nonlinear Time Series Prediction Using LS-SVM with Chaotic Mutation Evolutionary Programming for Parameter Optimization

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nonlinear time series prediction is studied by using an improved least squares support vector machine (LSSVM) regression based on chaotic mutation evolutionary programming (CMEP) approach for parameter optimization.We analyze how the prediction error varies with different parameters (σ, γ) in LS-SVM. In order to select appropriate parameters for the prediction model, we employ CMEP algorithm. Finally, Nasdaq stock data are predicted by using this LS-SVM regression based on CMEP, and satisfactory results are obtained.

  3. Dynamic Allocation of SPM Based on Time-Slotted Cache Conflict Graph for System Optimization

    Science.gov (United States)

    Wu, Jianping; Ling, Ming; Zhang, Yang; Mei, Chen; Wang, Huan

    This paper proposes a novel dynamic Scratch-pad Memory allocation strategy to optimize the energy consumption of the memory sub-system. Firstly, the whole program execution process is sliced into several time slots according to the temporal dimension; thereafter, a Time-Slotted Cache Conflict Graph (TSCCG) is introduced to model the behavior of Data Cache (D-Cache) conflicts within each time slot. Then, Integer Nonlinear Programming (INP) is implemented, which can avoid time-consuming linearization process, to select the most profitable data pages. Virtual Memory System (VMS) is adopted to remap those data pages, which will cause severe Cache conflicts within a time slot, to SPM. In order to minimize the swapping overhead of dynamic SPM allocation, a novel SPM controller with a tightly coupled DMA is introduced to issue the swapping operations without CPU's intervention. Last but not the least, this paper discusses the fluctuation of system energy profit based on different MMU page size as well as the Time Slot duration quantitatively. According to our design space exploration, the proposed method can optimize all of the data segments, including global data, heap and stack data in general, and reduce the total energy consumption by 27.28% on average, up to 55.22% with a marginal performance promotion. And comparing to the conventional static CCG (Cache Conflicts Graph), our approach can obtain 24.7% energy profit on average, up to 30.5% with a sight boost in performance.

  4. Developing an Inspection Optimization Model Based on the Delay-Time Concept

    Directory of Open Access Journals (Sweden)

    Ehsan Nazemi

    2015-01-01

    Full Text Available Infrastructures are considered as important facilities required for every country and society to be able to work properly. Aging and deterioration of such structures during their lifetime are a major concern both for maintenance researchers in the academic world and for the practitioners. This concern is mainly because the deterioration increases the maintenance costs dramatically and lowers the reliability, availability, and safety of the structural system. Preventive maintenance and inspection activities are the most usual means for keeping the structure in a good condition. This paper utilizes the concept of delay-time for developing the optimal inspection policy for deteriorating structures. In the proposed stochastic model, discrete times of inspection activities are taken as the decision variables of an optimization problem, in a way that the obtained aperiodic (nonuniform inspection schedule minimizes the total downtime ratio of the structure. To illustrate the model capabilities, various numerical examples are solved and results are compared with the traditional periodic (uniform inspection policies. The results indicate the substantial reduction in system downtime due to the wisely planned inspection schedule and the appropriate utilization of delay-time concept, which is indeed a powerful framework for inspection optimization problems.

  5. 12 hours after cerebral ischemia is the optimal time for bone marrow mesenchymal stem cell transplantation

    Institute of Scientific and Technical Information of China (English)

    Seyed Mojtaba Hosseini; Mohammad Farahmandnia; Zahra Razi; Somayeh Delavarifar; Benafsheh Shakibajahromi

    2015-01-01

    Cell therapy using stem cell transplantation against cerebral ischemia has been reported. However, it remains controversial regarding the optimal time for cell transplantation and the transplantation route. Rat models of cerebral ischemia were established by occlusion of the middle cerebral artery. At 1, 12 hours, 1, 3, 5 and 7 days after cerebral ischemia, bone marrow mesenchymal stem cells were injected via the tail vein. At 28 days after cerebral ischemia, rat neurological function was evaluated using a 6-point grading scale and the pathological change of ischemic cerebral tissue was observed by hematoxylin-eosin staining. Under the lfuorescence microscope, the migration of bone marrow mesenchymal stem cells was examined by PKH labeling. Caspase-3 activity was measured using spectrophotometry. The optimal neurological function recovery, lowest degree of ischemic cerebral damage, greatest number of bone marrow mesenchymal stem cells migrating to peri-ischemic area, and lowest caspase-3 activity in the ischemic cerebral tissue were observed in rats that underwent bone marrow mesenchymal stem cell transplantation at 12 hours after cerebral ischemia. These ifndings suggest that 12 hours after cerebral ischemia is the optimal time for tail vein injection of bone marrow mesenchymal stem cell transplantation against cerebral ischemia, and the strongest neuroprotective effect of this cell therapy appears at this time.

  6. Optimal time for human umbilical cord blood cell transplantation in rats with myocardial infarction

    Institute of Scientific and Technical Information of China (English)

    XING Yun-li; SHEN Lu-hua; LI Hong-wei; ZHANG Yu-chen; ZHAO Lin; ZHAO Shu-mei; XU Qing

    2009-01-01

    Background Cell therapy for cardiac regeneration is still under investigation. To date there have been a limited number of studies describing the optimal time for cell injection. The present study aimed to examine the optimal time for human umbilical cord blood cells (HUCBCs) transplantation after myocardial infarction (MI).Methods The animals underwent MI by ligation of the left anterior descending coronary artery and received an intravenous injection of equal volumes of HUCBCs or phosphate buffered saline at days 1,5,10 and 30 after MI. HUCBCs were detected by immunostaining against human human leucocyte antigen (HLA). Cardiac function, histological analysis and measurement of vascular endothelial growth factor (VEGF) were performed 4 weeks after cell transplantation. Results HUCBCs transplantation could improve cardiac function in rats that received transplantation at 5 and 10 days after MI. The best benefit was achieved in rats that received cells at 10-day after MI. Survival of engrafted HUCBCs, angiogenesis and VEGF expression were more obvious in the 10-day transplantation group than in the other transplantation groups. No evidence of cardiomyocyte regeneration was detected in any transplanted rats. Conclusions HUCBCs transplantation could improve cardiac function in rats that received HUCBCs at days 5 and 10 after MI with the optimal time for transplantation being 10 days post MI. Angiogenesis, but not cardiomyocyte regeneration, played a key role in the cardiac function improvement.

  7. 12 hours after cerebral ischemia is the optimal time for bone marrow mesenchymal stem cell transplantation

    Directory of Open Access Journals (Sweden)

    Seyed Mojtaba Hosseini

    2015-01-01

    Full Text Available Cell therapy using stem cell transplantation against cerebral ischemia has been reported. However, it remains controversial regarding the optimal time for cell transplantation and the transplantation route. Rat models of cerebral ischemia were established by occlusion of the middle cerebral artery. At 1, 12 hours, 1, 3, 5 and 7 days after cerebral ischemia, bone marrow mesenchymal stem cells were injected via the tail vein. At 28 days after cerebral ischemia, rat neurological function was evaluated using a 6-point grading scale and the pathological change of ischemic cerebral tissue was observed by hematoxylin-eosin staining. Under the fluorescence microscope, the migration of bone marrow mesenchymal stem cells was examined by PKH labeling. Caspase-3 activity was measured using spectrophotometry. The optimal neurological function recovery, lowest degree of ischemic cerebral damage, greatest number of bone marrow mesenchymal stem cells migrating to peri-ischemic area, and lowest caspase-3 activity in the ischemic cerebral tissue were observed in rats that underwent bone marrow mesenchymal stem cell transplantation at 12 hours after cerebral ischemia. These findings suggest that 12 hours after cerebral ischemia is the optimal time for tail vein injection of bone marrow mesenchymal stem cell transplantation against cerebral ischemia, and the strongest neuroprotective effect of this cell therapy appears at this time.

  8. Optimal timing in screening patients with congestive heart failure and healthy subjects during circadian observation.

    Science.gov (United States)

    Jong, Tai-Lang; Chang, Ben; Kuo, Cheng-Deng

    2011-02-01

    Congestive heart failure (CHF) is a major medical challenge in developed countries. In order to screen patients with CHF and healthy subjects during circadian observation, accurate judgment and fast response are imperative. In this study, optimal timing during circadian observation via the heart rate variability (HRV) was sought. We tested 29 CHF patients and 54 healthy subjects in the control group from the interbeat interval databases of PhysioBank. By invoking the α1 parameter in detrended fluctuation analysis of HRV, we found that it could be used as an indicator to screen the patients with CHF and subjects in normal sinus rhythm (NSR) under Kruskal-Wallis test. By invoking Fano factor, the optimal timing to screen CHF patients and healthy subjects was found to be from 7 PM to 9 PM during the circadian observation. In addition, this result is robust in a sense that the same result can be achieved by using different ECG recording lengths of 2, 5, 10, … , and 120 min, respectively. Furthermore, a support vector machine was employed to classify CHF and NSR with α1 parameter of a moving half-hour ECG recordings via leave-one-out cross validation. The results showed that the superlative screening performance was obtained in the 7 pm-9 pm period during circadian observation. It is believed that this result of optimal timing will be helpful in the non-invasive monitoring and screening of CHF patients and healthy subjects in the clinical practice. PMID:20953708

  9. A Class of Prediction-Correction Methods for Time-Varying Convex Optimization

    Science.gov (United States)

    Simonetto, Andrea; Mokhtari, Aryan; Koppel, Alec; Leus, Geert; Ribeiro, Alejandro

    2016-09-01

    This paper considers unconstrained convex optimization problems with time-varying objective functions. We propose algorithms with a discrete time-sampling scheme to find and track the solution trajectory based on prediction and correction steps, while sampling the problem data at a constant rate of $1/h$, where $h$ is the length of the sampling interval. The prediction step is derived by analyzing the iso-residual dynamics of the optimality conditions. The correction step adjusts for the distance between the current prediction and the optimizer at each time step, and consists either of one or multiple gradient steps or Newton steps, which respectively correspond to the gradient trajectory tracking (GTT) or Newton trajectory tracking (NTT) algorithms. Under suitable conditions, we establish that the asymptotic error incurred by both proposed methods behaves as $O(h^2)$, and in some cases as $O(h^4)$, which outperforms the state-of-the-art error bound of $O(h)$ for correction-only methods in the gradient-correction step. Moreover, when the characteristics of the objective function variation are not available, we propose approximate gradient and Newton tracking algorithms (AGT and ANT, respectively) that still attain these asymptotical error bounds. Numerical simulations demonstrate the practical utility of the proposed methods and that they improve upon existing techniques by several orders of magnitude.

  10. Efficient Inventory Optimization of Multi Product, Multiple Suppliers with Lead Time using PSO

    CERN Document Server

    Narmadha, S; Sathish, G

    2010-01-01

    With information revolution, increased globalization and competition, supply chain has become longer and more complicated than ever before. These developments bring supply chain management to the forefront of the managements attention. Inventories are very important in a supply chain. The total investment in inventories is enormous, and the management of inventory is crucial to avoid shortages or delivery delays for the customers and serious drain on a companys financial resources. The supply chain cost increases because of the influence of lead times for supplying the stocks as well as the raw materials. Practically, the lead times will not be same through out all the periods. Maintaining abundant stocks in order to avoid the impact of high lead time increases the holding cost. Similarly, maintaining fewer stocks because of ballpark lead time may lead to shortage of stocks. This also happens in the case of lead time involved in supplying raw materials. A better optimization methodology that utilizes the Part...

  11. Optimization of time-delayed feedback control of seismically excited building structures

    Institute of Scientific and Technical Information of China (English)

    Xue-ping LI; Wei-qiu ZHU; Zu-guang YING

    2008-01-01

    An optimization method for time-delayed feedback control of partially observable linear building structures subjected to seismic excitation is proposed. A time-delayed control problem of partially observable linear building structure under horizontal ground acceleration excitation is formulated and converted into that of completely observable linear structure by using separation principle. The time-delayed control forces are approximately expressed in terms of control forces without time delay. The control system is then governed by Ito stochastic differential equations for the conditional means of system states and then transformed into those for the conditional means of modal energies by using the stochastic averaging method for quasi-Hamiltonian systems. The control law is assumed to be modal velocity feedback control with time delay and the unknown control gains are determined by the modal performance indices. A three-storey building structure is taken as example to illustrate the proposal method and the numerical results are confirmed by using Monte Carlo simulation.

  12. THE OPTIMAL TIME FOR SUBSTITUTION OF Eucalyptus spp. PLANTATIONS –THE TECHNOLOGICAL PROGRESS CASE

    Directory of Open Access Journals (Sweden)

    José Luiz Pereira de Rezende

    2005-03-01

    Full Text Available The importance of technological progress for the Brazilian forest enterprises cannot be denied. Its influencecomprehends all the activities, but can be summarized in the increase of income via yield increase or cost reduction and, mainly,in the two cases occurring together. Technological effects influence, among other aspects, the cutting age and the optimal time torenewal (a new plantinting or “reforma” Eucalyptus plantations. Studies to determine these times are not so common in theliterature since it requires both forestry and economic knowledge. Before renewing an Eucalyptus stand, it is necessary totechnically and economically to define the optimal cut age the original planting and the coppicings and after how many cuttingsthe substitution of the plantations should be done. This study aimed at studying the optimal time to substitute Eucalyptus spp.Plantations, considering the gains earned through technological progress; to determine the cutting age of the population, theincome being increasing and the cost being decreasing; to propose and verify the efficiency of a mathematical model whichallows modeling the effects of technological progress; to study the substitution chain between 1960 and 2000 and between 2000and 2040, considering technological progress; and to test the results in a case study. The Gompertz Function was employed toobtain the volumes at the various ages. The criterion employed for the economic evaluation of the projects was the Presente NetValue (PNV. The proposed model allowed the calculation of yields and costs through time, study the effect of yield increaseand cost reduction and determine the rates of these increase and, or, reductions as well as determining rates which served asmoderators so that the yield and costs did not reach unreal values. It was concluded that: The rotation, with current values, is at 7years of age; the model proved to be efficient for estimates up to 40 years; with the income and costs from

  13. A checklist of nematode parasites from Indonesian murids.

    Science.gov (United States)

    Dewi, Kartika; Purwaningsih, Endang

    2013-01-24

    A checklist of nematode parasites from Indonesian murids with their geographic distribution is presented. This checklist is compiled from three sources: the catalogue of nematode parasites of Museum Zoologicum Bogoriense (unpublished specimens in the collection), data from our previous research and articles on nematodes of Indonesian murids. This checklist is presented as a list of nematode parasites with host information, and a host list with information on their nematodes. This paper reports 38 nominal species of nematodes and 13 species identified to the generic level only. The nematodes reported comprise 32 genera and 17 families parasitizing 32 species of Indonesian murids.

  14. Convergence Time Analysis of Particle Swarm Optimization Based on Particle Interaction

    Directory of Open Access Journals (Sweden)

    Chao-Hong Chen

    2011-01-01

    Full Text Available We analyze the convergence time of particle swarm optimization (PSO on the facet of particle interaction. We firstly introduce a statistical interpretation of social-only PSO in order to capture the essence of particle interaction, which is one of the key mechanisms of PSO. We then use the statistical model to obtain theoretical results on the convergence time. Since the theoretical analysis is conducted on the social-only model of PSO, instead of on common models in practice, to verify the validity of our results, numerical experiments are executed on benchmark functions with a regular PSO program.

  15. A pseudospectral feedback method for real-time optimal guidance of reentry vehicles

    OpenAIRE

    Bollino, Kevin P.; Ross, I. Michael

    2007-01-01

    The article of record as published may be located at http://ieeexplore.ieee.org Proceedings of the 2007 American Control Conference Marriott Marquis Hotel at Times Square New York City, USA, July 11-13, 2007 Motivated by the emerging needs of the next generation of reusable launch vehicles (RLV), a pseudospectral (PS) feedback method is designed and applied to guide an RLV across multiple phases of an entry trajectory. That is, by generating real-time, open-loop, optimal controls, it...

  16. Time-optimal guaranteed search of mobile object in the plane

    Directory of Open Access Journals (Sweden)

    Avetisyan V.V.

    2015-03-01

    Full Text Available A problem of time-optimal guaranteed search of moving object with controllable speed in plane is observed, where in the initial moment only the circular of the sought object is known. The sought object is a object with controllable speed. The discovery, i.e. the identification of the precise coordinates of the object, is implemented through the moving information basis of the cone, the apex of which is connected to the current coordinates of the sough object. It is required to locate the object as quickly as possible. A control algorithm is proposed, in which r a guaranteed search of the sought object in minimal time is completed.

  17. Toward the Optimal Configuration of Dynamic Voltage Scaling Points in Real-Time Applications

    Institute of Scientific and Technical Information of China (English)

    Hui-Zhan Yi; Xue-Jun Yang

    2006-01-01

    In real-time applications, compiler-directed dynamic voltage scaling (DVS) could reduce energy consumption efficiently, where compiler put voltage scaling points in the proper places, and the supply voltage and clock frequency were adjusted to the relationship between the reduced time and the reduced workload. This paper presents the optimal configuration of dynamic voltage scaling points without voltage scaling overhead, which minimizes energy consumption. The conclusion is proved theoretically. Finally, it is confirmed by simulations with equally-spaced voltage scaling configuration.

  18. The Optimization of Preventive Maintenance Scheduling for Production Machine of Production System in Finite Time Horizon

    Institute of Scientific and Technical Information of China (English)

    韩帮军; 潘军; 范秀敏; 马登哲

    2004-01-01

    The recursion relation of preventive maintenance (PM) cycle is built up concerning the concept of effective age and age setback factor proposed in this paper, which illustrates the dynamic relationship between failure rate and preventive maintenance activity. And the nonlinear optimal PM policy model satisfying the reliability constraints in finite time horizon following Weibull distribution is proposed. The model built in this paper avoids the shortcoming of steady analytical PM model in infinite time horizon and can be used to aid scheduling the maintenance plan and providing decision supporting for job shop scheduling.

  19. A Hybrid Chaos-Particle Swarm Optimization Algorithm for the Vehicle Routing Problem with Time Window

    Directory of Open Access Journals (Sweden)

    Qi Hu

    2013-04-01

    Full Text Available State-of-the-art heuristic algorithms to solve the vehicle routing problem with time windows (VRPTW usually present slow speeds during the early iterations and easily fall into local optimal solutions. Focusing on solving the above problems, this paper analyzes the particle encoding and decoding strategy of the particle swarm optimization algorithm, the construction of the vehicle route and the judgment of the local optimal solution. Based on these, a hybrid chaos-particle swarm optimization algorithm (HPSO is proposed to solve VRPTW. The chaos algorithm is employed to re-initialize the particle swarm. An efficient insertion heuristic algorithm is also proposed to build the valid vehicle route in the particle decoding process. A particle swarm premature convergence judgment mechanism is formulated and combined with the chaos algorithm and Gaussian mutation into HPSO when the particle swarm falls into the local convergence. Extensive experiments are carried out to test the parameter settings in the insertion heuristic algorithm and to evaluate that they are corresponding to the data’s real-distribution in the concrete problem. It is also revealed that the HPSO achieves a better performance than the other state-of-the-art algorithms on solving VRPTW.

  20. Actor-critic-based optimal tracking for partially unknown nonlinear discrete-time systems.

    Science.gov (United States)

    Kiumarsi, Bahare; Lewis, Frank L

    2015-01-01

    This paper presents a partially model-free adaptive optimal control solution to the deterministic nonlinear discrete-time (DT) tracking control problem in the presence of input constraints. The tracking error dynamics and reference trajectory dynamics are first combined to form an augmented system. Then, a new discounted performance function based on the augmented system is presented for the optimal nonlinear tracking problem. In contrast to the standard solution, which finds the feedforward and feedback terms of the control input separately, the minimization of the proposed discounted performance function gives both feedback and feedforward parts of the control input simultaneously. This enables us to encode the input constraints into the optimization problem using a nonquadratic performance function. The DT tracking Bellman equation and tracking Hamilton-Jacobi-Bellman (HJB) are derived. An actor-critic-based reinforcement learning algorithm is used to learn the solution to the tracking HJB equation online without requiring knowledge of the system drift dynamics. That is, two neural networks (NNs), namely, actor NN and critic NN, are tuned online and simultaneously to generate the optimal bounded control policy. A simulation example is given to show the effectiveness of the proposed method. PMID:25312944

  1. A policy iteration approach to online optimal control of continuous-time constrained-input systems.

    Science.gov (United States)

    Modares, Hamidreza; Naghibi Sistani, Mohammad-Bagher; Lewis, Frank L

    2013-09-01

    This paper is an effort towards developing an online learning algorithm to find the optimal control solution for continuous-time (CT) systems subject to input constraints. The proposed method is based on the policy iteration (PI) technique which has recently evolved as a major technique for solving optimal control problems. Although a number of online PI algorithms have been developed for CT systems, none of them take into account the input constraints caused by actuator saturation. In practice, however, ignoring these constraints leads to performance degradation or even system instability. In this paper, to deal with the input constraints, a suitable nonquadratic functional is employed to encode the constraints into the optimization formulation. Then, the proposed PI algorithm is implemented on an actor-critic structure to solve the Hamilton-Jacobi-Bellman (HJB) equation associated with this nonquadratic cost functional in an online fashion. That is, two coupled neural network (NN) approximators, namely an actor and a critic are tuned online and simultaneously for approximating the associated HJB solution and computing the optimal control policy. The critic is used to evaluate the cost associated with the current policy, while the actor is used to find an improved policy based on information provided by the critic. Convergence to a close approximation of the HJB solution as well as stability of the proposed feedback control law are shown. Simulation results of the proposed method on a nonlinear CT system illustrate the effectiveness of the proposed approach. PMID:23706414

  2. Operational optimization and real-time control of fuel-cell systems

    Science.gov (United States)

    Hasikos, J.; Sarimveis, H.; Zervas, P. L.; Markatos, N. C.

    Fuel cells is a rapidly evolving technology with applications in many industries including transportation, and both portable and stationary power generation. The viability, efficiency and robustness of fuel-cell systems depend strongly on optimization and control of their operation. This paper presents the development of an integrated optimization and control tool for Proton Exchange Membrane Fuel-Cell (PEMFC) systems. Using a detailed simulation model, a database is generated first, which contains steady-state values of the manipulated and controlled variables over the full operational range of the fuel-cell system. In a second step, the database is utilized for producing Radial Basis Function (RBF) neural network "meta-models". In the third step, a Non-Linear Programming Problem (NLP) is formulated, that takes into account the constraints and limitations of the system and minimizes the consumption of hydrogen, for a given value of power demand. Based on the formulation and solution of the NLP problem, a look-up table is developed, containing the optimal values of the system variables for any possible value of power demand. In the last step, a Model Predictive Control (MPC) methodology is designed, for the optimal control of the system response to successive sep-point changes of power demand. The efficiency of the produced MPC system is illustrated through a number of simulations, which show that a successful dynamic closed-loop behaviour can be achieved, while at the same time the consumption of hydrogen is minimized.

  3. Advances in LWD pressure measurements: smart, time optimized pretests and on demand real-time transmission applications

    Energy Technology Data Exchange (ETDEWEB)

    Serafim, Robson; Ferraris, Paolo [Schlumberger, Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The StethoScope Logging While Drilling (LWD) Pressure Measurement, introduced in Brazil in 2005, has been extensively used in deep water environment to provide reservoir pressure and mobility in real-time. In the last three years the StethoScope service was further enhanced to allow better real time monitoring using a larger transmission rate, higher RT data resolution and remote visualization. In order to guarantee stable formation pressures with a limited test duration under a wide range of conditions, Time Optimized Pretests (TOP) were developed. These tests adjust automatically drawdown and buildup parameters as a function of formation characteristics (pressure/mobility) without requiring any input from the operator. On-demand frame (ODF), an advanced telemetry triggered automatically during the pressure tests, allowed to increase equivalent transmission rate and resolution and to include quality indices computed downhole. This paper is focused on the TOP and ODF Field Test results in Brazil, which proved to be useful and reliable options for better real-time decisions together with remote monitoring visualization implemented by the RTMonitor program. (author)

  4. Optimization of mine ventilation fan speeds according to ventilation on demand and time of use tariff

    International Nuclear Information System (INIS)

    Highlights: • DSM techniques are applied to an underground mine ventilation network. • A minimization model is solved to find the optimal speeds of the main mine fan. • Ventilation on demand (VOD) leads to a saving of USD 213160. • The optimal mining schedule, together with VOD, leads to a saving of USD 277035. • According to a case study, a maximum of 2 540 035 kW h can be saved per year. - Abstract: In the current situation of the energy crisis, the mining industry has been identified as a promising area for application of demand side management (DSM) techniques. This paper investigates the potential for energy-cost savings and actual energy savings, by implementation of variable speed drives to ventilation fans in underground mines. In particular, ventilation on demand is considered in the study, i.e., air volume is adjusted according to the demand at varying times. Two DSM strategies, energy efficiency (EE) and load management (LM), are formulated and analysed. By modelling the network with the aid of Kirchhoff’s laws and Tellegen’s theorem, a nonlinear constrained minimization model is developed, with the objective of achieving EE. The model is also made to adhere to the fan laws, such that the fan power at its operating points is found to achieve realistic results. LM is achieved by finding the optimal starting time of the mining schedule, according to the time of use (TOU) tariff. A case study is shown to demonstrate the effects of the optimization model. The study suggests that by combining load shifting and energy efficiency techniques, an annual energy saving of 2 540 035 kW h is possible, leading to an annual cost saving of USD 277035

  5. Performance deterioration modeling and optimal preventive maintenance strategy under scheduled servicing subject to mission time

    Directory of Open Access Journals (Sweden)

    Li Dawei

    2014-08-01

    Full Text Available Servicing is applied periodically in practice with the aim of restoring the system state and prolonging the lifetime. It is generally seen as an imperfect maintenance action which has a chief influence on the maintenance strategy. In order to model the maintenance effect of servicing, this study analyzes the deterioration characteristics of system under scheduled servicing. And then the deterioration model is established from the failure mechanism by compound Poisson process. On the basis of the system damage value and failure mechanism, the failure rate refresh factor is proposed to describe the maintenance effect of servicing. A maintenance strategy is developed which combines the benefits of scheduled servicing and preventive maintenance. Then the optimization model is given to determine the optimal servicing period and preventive maintenance time, with an objective to minimize the system expected life-cycle cost per unit time and a constraint on system survival probability for the duration of mission time. Subject to mission time, it can control the ability of accomplishing the mission at any time so as to ensure the high dependability. An example of water pump rotor relating to scheduled servicing is introduced to illustrate the failure rate refresh factor and the proposed maintenance strategy. Compared with traditional methods, the numerical results show that the failure rate refresh factor can describe the maintenance effect of servicing more intuitively and objectively. It also demonstrates that this maintenance strategy can prolong the lifetime, reduce the total lifetime maintenance cost and guarantee the dependability of system.

  6. Optimal Strong-Stability-Preserving Runge–Kutta Time Discretizations for Discontinuous Galerkin Methods

    KAUST Repository

    Kubatko, Ethan J.

    2013-10-29

    Discontinuous Galerkin (DG) spatial discretizations are often used in a method-of-lines approach with explicit strong-stability-preserving (SSP) Runge–Kutta (RK) time steppers for the numerical solution of hyperbolic conservation laws. The time steps that are employed in this type of approach must satisfy Courant–Friedrichs–Lewy stability constraints that are dependent on both the region of absolute stability and the SSP coefficient of the RK method. While existing SSPRK methods have been optimized with respect to the latter, it is in fact the former that gives rise to stricter constraints on the time step in the case of RKDG stability. Therefore, in this work, we present the development of new “DG-optimized” SSPRK methods with stability regions that have been specifically designed to maximize the stable time step size for RKDG methods of a given order in one space dimension. These new methods represent the best available RKDG methods in terms of computational efficiency, with significant improvements over methods using existing SSPRK time steppers that have been optimized with respect to SSP coefficients. Second-, third-, and fourth-order methods with up to eight stages are presented, and their stability properties are verified through application to numerical test cases.

  7. Enhance the Accuracy of Medication Histories for the Elderly by Using an Electronic Medication Checklist

    Science.gov (United States)

    Wang, Tiankai; Biederman, Sue

    2012-01-01

    Medication errors may result in serious safety issues for patients. Medication error issues are more prevalent among elderly patients, who take more medications and have prescriptions that change frequently. The challenge of obtaining accurate medication histories for the elderly at the time of hospital admission creates the potential for medication errors starting at admission. A study at a central Texas hospital was conducted to assess whether an electronic medication checklist can enhance the accuracy of medication histories for the elderly. The empirical outcome demonstrated that medication errors were significantly reduced by using an electronic medication checklist at the time of admission. The findings of this study suggest that implementing electronic health record systems with decision support for identifying inaccurate doses and frequencies of prescribed medicines will increase the accuracy of patients’ medication histories. PMID:23209450

  8. An Empirical Comparative Study of Checklist-based and Ad Hoc Code Reading Techniques in a Distributed Groupware Environment

    Directory of Open Access Journals (Sweden)

    Adenike O. Osofisan

    2009-09-01

    Full Text Available Software inspection is a necessary and important tool for software quality assurance. Since it was introduced by Fagan at IBM in 1976, arguments exist as to which method should be adopted to carry out the exercise, whether it should be paper-based or tool-based, and what reading technique should be used on the inspection document. Extensive works have been done to determine the effectiveness of reviewers in paper-based environment when using ad hoc and checklist reading techniques. In this work, we take the software inspection research further by examining whether there is going to be any significant difference in defect detection effectiveness of reviewers when they use either ad hoc or checklist reading techniques in a distributed groupware environment. Twenty final year undergraduate students of computer science, divided into ad hoc and checklist reviewers groups of ten members each were employed to inspect a medium-sized java code synchronously on groupware deployed on the Internet. The data obtained were subjected to tests of hypotheses using independent t-test and correlation coefficients. Results from the study indicate that there are no significant differences in the defect detection effectiveness, effort in terms of time taken in minutes and false positives reported by the reviewers using either ad hoc or checklist based reading techniques in the distributed groupware environment studied.Key words: Software Inspection, Ad hoc, Checklist, groupware.

  9. Temporal variation of optimal UV exposure time over Korea: risks and benefits of surface UV radiation

    Science.gov (United States)

    Lee, Y. G.; Koo, J. H.

    2015-12-01

    Solar UV radiation in a wavelength range between 280 to 400 nm has both positive and negative influences on human body. Surface UV radiation is the main natural source of vitamin D, providing the promotion of bone and musculoskeletal health and reducing the risk of a number of cancers and other medical conditions. However, overexposure to surface UV radiation is significantly related with the majority of skin cancer, in addition other negative health effects such as sunburn, skin aging, and some forms of eye cataracts. Therefore, it is important to estimate the optimal UV exposure time, representing a balance between reducing negative health effects and maximizing sufficient vitamin D production. Previous studies calculated erythemal UV and vitamin-D UV from the measured and modelled spectral irradiances, respectively, by weighting CIE Erythema and Vitamin D3 generation functions (Kazantzidis et al., 2009; Fioletov et al., 2010). In particular, McKenzie et al. (2009) suggested the algorithm to estimate vitamin-D production UV from erythemal UV (or UV index) and determined the optimum conditions of UV exposure based on skin type Ⅱ according to the Fitzpatrick (1988). Recently, there are various demands for risks and benefits of surface UV radiation on public health over Korea, thus it is necessary to estimate optimal UV exposure time suitable to skin type of East Asians. This study examined the relationship between erythemally weighted UV (UVEry) and vitamin D weighted UV (UVVitD) over Korea during 2004-2012. The temporal variations of the ratio (UVVitD/UVEry) were also analyzed and the ratio as a function of UV index was applied in estimating the optimal UV exposure time. In summer with high surface UV radiation, short exposure time leaded to sufficient vitamin D and erythema and vice versa in winter. Thus, the balancing time in winter was enough to maximize UV benefits and minimize UV risks.

  10. 32 CFR Appendix G to Part 505 - Management Control Evaluation Checklist

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Management Control Evaluation Checklist G...—Management Control Evaluation Checklist (a) Function. The function covered by this checklist is DA Privacy... Program Coordinators in evaluating the key management controls listed below. This checklist is...

  11. Optimal timing for managed relocation of species faced with climate change

    Science.gov (United States)

    McDonald Madden, Eve; Runge, Michael C.; Possingham, Hugh P.; Martin, Tara G.

    2011-01-01

    Managed relocation is a controversial climate-adaptation strategy to combat negative climate change impacts on biodiversity. While the scientific community debates the merits of managed relocation, species are already being moved to new areas predicted to be more suitable under climate change. To inform these moves, we construct a quantitative decision framework to evaluate the timing of relocation in the face of climate change. We find that the optimal timing depends on many factors, including the size of the population, the demographic costs of translocation and the expected carrying capacities over time in the source and destination habitats. In some settings, such as when a small population would benefit from time to grow before risking translocation losses, haste is ill advised. We also find that active adaptive management is valuable when the effect of climate change on source habitat is uncertain, and leads to delayed movement.

  12. Mackey-Glass noisy chaotic time series prediction by a swarm-optimized neural network

    Science.gov (United States)

    López-Caraballo, C. H.; Salfate, I.; Lazzús, J. A.; Rojas, P.; Rivera, M.; Palma-Chilla, L.

    2016-05-01

    In this study, an artificial neural network (ANN) based on particle swarm optimization (PSO) was developed for the time series prediction. The hybrid ANN+PSO algorithm was applied on Mackey-Glass noiseless chaotic time series in the short-term and long-term prediction. The performance prediction is evaluated and compared with similar work in the literature, particularly for the long-term forecast. Also, we present properties of the dynamical system via the study of chaotic behaviour obtained from the time series prediction. Then, this standard hybrid ANN+PSO algorithm was complemented with a Gaussian stochastic procedure (called stochastic hybrid ANN+PSO) in order to obtain a new estimator of the predictions that also allowed us compute uncertainties of predictions for noisy Mackey-Glass chaotic time series. We study the impact of noise for three cases with a white noise level (σ N ) contribution of 0.01, 0.05 and 0.1.

  13. Real-time process optimization based on grey-box neural models

    Directory of Open Access Journals (Sweden)

    F. A. Cubillos

    2007-09-01

    Full Text Available This paper investigates the feasibility of using grey-box neural models (GNM in Real Time Optimization (RTO. These models are based on a suitable combination of fundamental conservation laws and neural networks, being used in at least two different ways: to complement available phenomenological knowledge with empirical information, or to reduce dimensionality of complex rigorous physical models. We have observed that the benefits of using these simple adaptable models are counteracted by some difficulties associated with the solution of the optimization problem. Nonlinear Programming (NLP algorithms failed in finding the global optimum due to the fact that neural networks can introduce multimodal objective functions. One alternative considered to solve this problem was the use of some kind of evolutionary algorithms, like Genetic Algorithms (GA. Although these algorithms produced better results in terms of finding the appropriate region, they took long periods of time to reach the global optimum. It was found that a combination of genetic and nonlinear programming algorithms can be use to fast obtain the optimum solution. The proposed approach was applied to the Williams-Otto reactor, considering three different GNM models of increasing complexity. Results demonstrated that the use of GNM models and mixed GA/NLP optimization algorithms is a promissory approach for solving dynamic RTO problems.

  14. Near Optimal Event-Triggered Control of Nonlinear Discrete-Time Systems Using Neurodynamic Programming.

    Science.gov (United States)

    Sahoo, Avimanyu; Xu, Hao; Jagannathan, Sarangapani

    2016-09-01

    This paper presents an event-triggered near optimal control of uncertain nonlinear discrete-time systems. Event-driven neurodynamic programming (NDP) is utilized to design the control policy. A neural network (NN)-based identifier, with event-based state and input vectors, is utilized to learn the system dynamics. An actor-critic framework is used to learn the cost function and the optimal control input. The NN weights of the identifier, the critic, and the actor NNs are tuned aperiodically once every triggered instant. An adaptive event-trigger condition to decide the trigger instants is derived. Thus, a suitable number of events are generated to ensure a desired accuracy of approximation. A near optimal performance is achieved without using value and/or policy iterations. A detailed analysis of nontrivial inter-event times with an explicit formula to show the reduction in computation is also derived. The Lyapunov technique is used in conjunction with the event-trigger condition to guarantee the ultimate boundedness of the closed-loop system. The simulation results are included to verify the performance of the controller. The net result is the development of event-driven NDP.

  15. Near Optimal Event-Triggered Control of Nonlinear Discrete-Time Systems Using Neurodynamic Programming.

    Science.gov (United States)

    Sahoo, Avimanyu; Xu, Hao; Jagannathan, Sarangapani

    2016-09-01

    This paper presents an event-triggered near optimal control of uncertain nonlinear discrete-time systems. Event-driven neurodynamic programming (NDP) is utilized to design the control policy. A neural network (NN)-based identifier, with event-based state and input vectors, is utilized to learn the system dynamics. An actor-critic framework is used to learn the cost function and the optimal control input. The NN weights of the identifier, the critic, and the actor NNs are tuned aperiodically once every triggered instant. An adaptive event-trigger condition to decide the trigger instants is derived. Thus, a suitable number of events are generated to ensure a desired accuracy of approximation. A near optimal performance is achieved without using value and/or policy iterations. A detailed analysis of nontrivial inter-event times with an explicit formula to show the reduction in computation is also derived. The Lyapunov technique is used in conjunction with the event-trigger condition to guarantee the ultimate boundedness of the closed-loop system. The simulation results are included to verify the performance of the controller. The net result is the development of event-driven NDP. PMID:26285220

  16. Optimal discrete-time H∞/γ0 filtering and control under unknown covariances

    Science.gov (United States)

    Kogan, Mark M.

    2016-04-01

    New stochastic γ0 and mixed H∞/γ0 filtering and control problems for discrete-time systems under completely unknown covariances are introduced and solved. The performance measure γ0 is the worst-case steady-state averaged variance of the error signal in response to the stationary Gaussian white zero-mean disturbance with unknown covariance and identity variance. The performance measure H∞/γ0 is the worst-case power norm of the error signal in response to two input disturbances in different channels, one of which is the deterministic signal with a bounded energy and the other is the stationary Gaussian white zero-mean signal with a bounded variance provided the weighting sum of disturbance powers equals one. In this framework, it is possible to consider at the same time both deterministic and stochastic disturbances highlighting their mutual effects. Our main results provide the complete characterisations of the above performance measures in terms of linear matrix inequalities and therefore both the γ0 and H∞/γ0 optimal filters and controllers can be computed by convex programming. H∞/γ0 optimal solution is shown to be actually a trade-off between optimal solutions to the H∞ and γ0 problems for the corresponding channels.

  17. Time-optimal excitation of maximum quantum coherence: Physical limits and pulse sequences

    Science.gov (United States)

    Köcher, S. S.; Heydenreich, T.; Zhang, Y.; Reddy, G. N. M.; Caldarelli, S.; Yuan, H.; Glaser, S. J.

    2016-04-01

    Here we study the optimum efficiency of the excitation of maximum quantum (MaxQ) coherence using analytical and numerical methods based on optimal control theory. The theoretical limit of the achievable MaxQ amplitude and the minimum time to achieve this limit are explored for a set of model systems consisting of up to five coupled spins. In addition to arbitrary pulse shapes, two simple pulse sequence families of practical interest are considered in the optimizations. Compared to conventional approaches, substantial gains were found both in terms of the achieved MaxQ amplitude and in pulse sequence durations. For a model system, theoretically predicted gains of a factor of three compared to the conventional pulse sequence were experimentally demonstrated. Motivated by the numerical results, also two novel analytical transfer schemes were found: Compared to conventional approaches based on non-selective pulses and delays, double-quantum coherence in two-spin systems can be created twice as fast using isotropic mixing and hard spin-selective pulses. Also it is proved that in a chain of three weakly coupled spins with the same coupling constants, triple-quantum coherence can be created in a time-optimal fashion using so-called geodesic pulses.

  18. Real-time 3D dose calculation and display: a tool for plan optimization

    International Nuclear Information System (INIS)

    Purpose: Both human and computer optimization of treatment plans have advantages; humans are much better at global pattern recognition, and computers are much better at detailed calculations. A major impediment to human optimization of treatment plans by manipulation of beam parameters is the long time required for feedback to the operator on the effectiveness of a change in beam parameters. Our goal was to create a real-time dose calculation and display system that provides the planner with immediate (fraction of a second) feedback with displays of three-dimensional (3D) isodose surfaces, digitally reconstructed radiographs (DRRs), dose-volume histograms, and/or a figure of merit (FOM) (i.e., a single value plan score function). This will allow the experienced treatment planner to optimize a plan by adjusting beam parameters based on a direct indication of plan effectiveness, the FOM value, and to use 3D display of target, critical organs, DRRs, and isodose contours to guide changes aimed at improving the FOM value. Methods and Materials: We use computer platforms that contain easily utilized parallel processors and very tight coupling between calculation and display. We ported code running on a network of two workstations and an array of transputers to a single multiprocessor workstation. Our current high-performance graphics workstation contains four 150-MHz processors that can be readily used in a shared-memory multithreaded calculation. Results: When a 10 x 10-cm beam is moved, using an 8-mm dose grid, the full 3D dose matrix is recalculated using a Bentley-Milan-type dose calculation algorithm, and the 3D dose surface display is then updated, all in < 0.1 s. A 64 x 64-pixel DRR calculation can be performed in < 0.1 s. Other features, such as automated aperture calculation, are still required to make real-time feedback practical for clinical use. Conclusion: We demonstrate that real-time plan optimization using general purpose multiprocessor workstations is a

  19. On the optimal identification of tag sets in time-constrained RFID configurations.

    Science.gov (United States)

    Vales-Alonso, Javier; Bueno-Delgado, María Victoria; Egea-López, Esteban; Alcaraz, Juan José; Pérez-Mañogil, Juan Manuel

    2011-01-01

    In Radio Frequency Identification facilities the identification delay of a set of tags is mainly caused by the random access nature of the reading protocol, yielding a random identification time of the set of tags. In this paper, the cumulative distribution function of the identification time is evaluated using a discrete time Markov chain for single-set time-constrained passive RFID systems, namely those ones where a single group of tags is assumed to be in the reading area and only for a bounded time (sojourn time) before leaving. In these scenarios some tags in a set may leave the reader coverage area unidentified. The probability of this event is obtained from the cumulative distribution function of the identification time as a function of the sojourn time. This result provides a suitable criterion to minimize the probability of losing tags. Besides, an identification strategy based on splitting the set of tags in smaller subsets is also considered. Results demonstrate that there are optimal splitting configurations that reduce the overall identification time while keeping the same probability of losing tags.

  20. On the Optimal Identification of Tag Sets in Time-Constrained RFID Configurations

    Directory of Open Access Journals (Sweden)

    Juan Manuel Pérez-Mañogil

    2011-03-01

    Full Text Available In Radio Frequency Identification facilities the identification delay of a set of tags is mainly caused by the random access nature of the reading protocol, yielding a random identification time of the set of tags. In this paper, the cumulative distribution function of the identification time is evaluated using a discrete time Markov chain for single-set time-constrained passive RFID systems, namely those ones where a single group of tags is assumed to be in the reading area and only for a bounded time (sojourn time before leaving. In these scenarios some tags in a set may leave the reader coverage area unidentified. The probability of this event is obtained from the cumulative distribution function of the identification time as a function of the sojourn time. This result provides a suitable criterion to minimize the probability of losing tags. Besides, an identification strategy based on splitting the set of tags in smaller subsets is also considered. Results demonstrate that there are optimal splitting configurations that reduce the overall identification time while keeping the same probability of losing tags.

  1. Optimal Training for Time-Selective Wireless Fading Channels Using Cutoff Rate

    Directory of Open Access Journals (Sweden)

    Tong Lang

    2006-01-01

    Full Text Available We consider the optimal allocation of resources—power and bandwidth—between training and data transmissions for single-user time-selective Rayleigh flat-fading channels under the cutoff rate criterion. The transmitter exploits statistical channel state information (CSI in the form of the channel Doppler spectrum to embed pilot symbols into the transmission stream. At the receiver, instantaneous, though imperfect, CSI is acquired through minimum mean-square estimation of the channel based on some set of pilot observations. We compute the ergodic cutoff rate for this scenario. Assuming estimator-based interleaving and -PSK inputs, we study two special cases in-depth. First, we derive the optimal resource allocation for the Gauss-Markov correlation model. Next, we validate and refine these insights by studying resource allocation for the Jakes model.

  2. Quasi-Newton-type optimized iterative learning control for discrete linear time invariant systems

    Institute of Scientific and Technical Information of China (English)

    Yan GENG; Xiaoe RUAN

    2015-01-01

    In this paper, a quasi-Newton-type optimized iterative learning control (ILC) algorithm is investigated for a class of discrete linear time-invariant systems. The proposed learning algorithm is to update the learning gain matrix by a quasi-Newton-type matrix instead of the inversion of the plant. By means of the mathematical inductive method, the monotone convergence of the proposed algorithm is analyzed, which shows that the tracking error monotonously converges to zero after a finite number of iterations. Compared with the existing optimized ILC algorithms, due to the superlinear convergence of quasi-Newton method, the proposed learning law operates with a faster convergent rate and is robust to the ill-condition of the system model, and thus owns a wide range of applications. Numerical simulations demonstrate the validity and effectiveness.

  3. Optimization of listening time of S-MAC for wireless sensor networks

    Institute of Scientific and Technical Information of China (English)

    LI Cheng; WANG Kui-ru; ZHANG Jin-long; ZHAO De-xin; LI Wang

    2009-01-01

    In wireless sensor networks, sensor nodes are usually battery-operated computing and sensing devices, hence operations are limited by the initially equipped batteries, which are hard to be recharged or replaced. In this sense, saving energy consumption becomes significant. As most energy waste is from the always-on wireless interface, S-MAC is suggested to reduce energy consumption by introducing periodic listen/sleep scheme. However, when designing the listening time, S-MAC fails to consider the traffic distribution factor. In this article, an optimization for this scheme is proposed based on the distribution model. Evaluations show that the optimized S-MAC achieves considerable improvement in energy and latency.

  4. Optimal Exponential Synchronization of Chaotic Systems with Multiple Time Delays via Fuzzy Control

    Directory of Open Access Journals (Sweden)

    Feng-Hsiag Hsiao

    2013-01-01

    Full Text Available This study presents an effective approach to realize the optimal exponential synchronization of multiple time-delay chaotic (MTDC systems. First, a neural network (NN model is employed to approximate the MTDC system. Then, a linear differential inclusion (LDI state-space representation is established for the dynamics of the NN model. Based on this LDI state-space representation, this study proposes a delay-dependent exponential stability criterion of the error system derived in terms of Lyapunov’s direct method to ensure that the trajectories of the slave system can approach those of the master system. Subsequently, the stability condition of this criterion is reformulated into a linear matrix inequality (LMI. Based on the LMI, a fuzzy controller is synthesized not only to realize the exponential synchronization but also to achieve the optimal performance by minimizing the disturbance attenuation level. Finally, a numerical example with simulations is provided to illustrate the concepts discussed throughout this work.

  5. OPTIMAL ERROR ESTIMATES FOR NEDELEC EDGE ELEMENTS FOR TIME-HARMONIC MAXWELL'S EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    Liuqiang Zhong; Shi Shu; Gabriel Wittum; Jinchao Xu

    2009-01-01

    In this paper, we obtain optimal error estimates in both L2-norm and H(curl)-norm for the Nedelec edge finite element approximation of the time-harmonic Maxwell's equations on a general Lipschitz domain discretized on quasi-uniform meshes. One key to our proof is to transform the L2 error estimates into the L2 estimate of a discrete divergence-free function which belongs to the edge finite element spaces, and then use the approximation of the discrete divergence-free function by the continuous divergence-free function and a duality argument for the continuous divergence-free function. For Nedelec's second type elements, we present an optimal convergence estimate which improves the best results available in the literature.

  6. OPTIMAL PWM BASED ON REAL—TIME SOLUTION WITH NEURAL NETWORK

    Institute of Scientific and Technical Information of China (English)

    ShenZhongting; YanYangguang

    2002-01-01

    A novel concept of neural network based control in pulse-width modulation(PWM)voltage source inverters is presented.On the one hand,the optimal switching an-gles are obtained in real time by the neural network based controller;on the other hand,the output voltage is ad-justed to fit the expected value by neural network when input voltage or loads change.The structure of neural network is simple and easy to be realized by DSP hard-ware system.No large memory used for the existing opti-mal PWM schemes is required in the system.Theoreticalanlysis of the proposed so-called sparse neural network is provided,and the stability of the system is proved.Un-der the control of neural network the error of output volt-age descends sharply,and the system outputs ac voltage with high precision.

  7. Checklist of collected plants from the Fish Springs study area

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This checklist contains 34 families and 99 species of plants which were identified from collections made in marshes at Fish Springs study area.

  8. First supplement to the lichen checklist of South Africa

    Directory of Open Access Journals (Sweden)

    Teuvo Ahti

    2016-05-01

    Full Text Available Details are given of errors and additions to the recently published checklist of lichens reported from South Africa (Fryday 2015. The overall number of taxa reported from South Africa is increased by one, to 1751.

  9. Optimal space-time attacks on system state estimation under a sparsity constraint

    Science.gov (United States)

    Lu, Jingyang; Niu, Ruixin; Han, Puxiao

    2016-05-01

    System state estimation in the presence of an adversary that injects false information into sensor readings has attracted much attention in wide application areas, such as target tracking with compromised sensors, secure monitoring of dynamic electric power systems, secure driverless cars, and radar tracking and detection in the presence of jammers. From a malicious adversary's perspective, the optimal strategy for attacking a multi-sensor dynamic system over sensors and over time is investigated. It is assumed that the system defender can perfectly detect the attacks and identify and remove sensor data once they are corrupted by false information injected by the adversary. With this in mind, the adversary's goal is to maximize the covariance matrix of the system state estimate by the end of attack period under a sparse attack constraint such that the adversary can only attack the system a few times over time and over sensors. The sparsity assumption is due to the adversary's limited resources and his/her intention to reduce the chance of being detected by the system defender. This becomes an integer programming problem and its optimal solution, the exhaustive search, is intractable with a prohibitive complexity, especially for a system with a large number of sensors and over a large number of time steps. Several suboptimal solutions, such as those based on greedy search and dynamic programming are proposed to find the attack strategies. Examples and numerical results are provided in order to illustrate the effectiveness and the reduced computational complexities of the proposed attack strategies.

  10. Optimizing Timing of Immunotherapy Improves Control of Tumors by Hypofractionated Radiation Therapy.

    Science.gov (United States)

    Young, Kristina H; Baird, Jason R; Savage, Talicia; Cottam, Benjamin; Friedman, David; Bambina, Shelly; Messenheimer, David J; Fox, Bernard; Newell, Pippa; Bahjat, Keith S; Gough, Michael J; Crittenden, Marka R

    2016-01-01

    The anecdotal reports of promising results seen with immunotherapy and radiation in advanced malignancies have prompted several trials combining immunotherapy and radiation. However, the ideal timing of immunotherapy with radiation has not been clarified. Tumor bearing mice were treated with 20Gy radiation delivered only to the tumor combined with either anti-CTLA4 antibody or anti-OX40 agonist antibody. Immunotherapy was delivered at a single timepoint around radiation. Surprisingly, the optimal timing of these therapies varied. Anti-CTLA4 was most effective when given prior to radiation therapy, in part due to regulatory T cell depletion. Administration of anti-OX40 agonist antibody was optimal when delivered one day following radiation during the post-radiation window of increased antigen presentation. Combination treatment of anti-CTLA4, radiation, and anti-OX40 using the ideal timing in a transplanted spontaneous mammary tumor model demonstrated tumor cures. These data demonstrate that the combination of immunotherapy and radiation results in improved therapeutic efficacy, and that the ideal timing of administration with radiation is dependent on the mechanism of action of the immunotherapy utilized. PMID:27281029

  11. PLANNED LEAD TIME OPTIMIZATION IN MATERIAL REQUIREMENT PLANNING ENVIRONMENT FOR MULTILEVEL PRODUCTION SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    Faicel HNAIEN; Alexandre DOLGUI; Mohamed-Aly OULD LOULY

    2008-01-01

    This paper deals with the problem of planned lead time calculation in a Material Requirement Planning (MRP) environment under stochastic lead times. The objective is to minimize the sum of holding and backlogging costs. The proposed approach is based on discrete time inventory control where the decision variables are integer. Two types of systems are considered: multi-level serial-production and assembly systems. For the serial production systems (one type of component at each level), a mathematical model is suggested. Then, it is proven that this model is equivalent to the well known discrete Newsboy Model. This directly provides the optimal values for the planned lead times. For multilevel assembly systems, a dedicated model is proposed and some properties of the decision variables and objective function are proven. These properties are used to calculate lower and upper limits on the decision variables and lower and upper bounds on the objective function. The obtained limits and bounds open the possibility to develop an efficient optimization algorithm using, for example, a Branch and Bound approach. The paper presents the proposed models in detail with corresponding proofs and several numerical examples. Some advantages of the suggested models and perspectives of this research are discussed.

  12. A modelling framework to optimize timing of haulout counts for estimating harbour seal (Phoca vitulina abundance

    Directory of Open Access Journals (Sweden)

    Michelle Cronin

    2010-09-01

    Full Text Available The time of year and day, the state of the tide and prevailing environmental conditions significantly influence seal haulout behaviour. Understanding these effects is fundamentally important in deriving accurate estimates of harbour seal abundance from haulout data. We present a modelling approach to assess the influence of these variables on seals’ haulout behaviour and, by identifying the combination of covariates during which seal abundance is highest, predict the optimal time and conditions for future surveys. Count data of harbour seals at haulouts in southwest Ireland collected during 2003-2005 were included in mixed additive models together with environmental covariates, including season, time of day and weather conditions. The models show maximum abundance at haulout sites occurred during midday periods during August and in late afternoon/early evening during September. Accurate national and local population estimates are essential for the effective monitoring of the conservation status of the species and for the identification, management and monitoring of Special Areas of Conservation (SAC in accordance with the EU Habitats Directive. Our model based approach provides a useful tool for optimising the timing of harbourseal surveys in Ireland and the modelling framework is useful for predicting optimal survey periods for other protected, endangered or significant species worldwide.

  13. Construction schedule simulation of a diversion tunnel based on the optimized ventilation time.

    Science.gov (United States)

    Wang, Xiaoling; Liu, Xuepeng; Sun, Yuefeng; An, Juan; Zhang, Jing; Chen, Hongchao

    2009-06-15

    Former studies, the methods for estimating the ventilation time are all empirical in construction schedule simulation. However, in many real cases of construction schedule, the many factors have impact on the ventilation time. Therefore, in this paper the 3D unsteady quasi-single phase models are proposed to optimize the ventilation time with different tunneling lengths. The effect of buoyancy is considered in the momentum equation of the CO transport model, while the effects of inter-phase drag, lift force, and virtual mass force are taken into account in the momentum source of the dust transport model. The prediction by the present model for airflow in a diversion tunnel is confirmed by the experimental values reported by Nakayama [Nakayama, In-situ measurement and simulation by CFD of methane gas distribution at a heading faces, Shigen-to-Sozai 114 (11) (1998) 769-775]. The construction ventilation of the diversion tunnel of XinTangfang power station in China is used as a case. The distributions of airflow, CO and dust in the diversion tunnel are analyzed. A theory method for GIS-based dynamic visual simulation for the construction processes of underground structure groups is presented that combines cyclic operation network simulation, system simulation, network plan optimization, and GIS-based construction processes' 3D visualization. Based on the ventilation time the construction schedule of the diversion tunnel is simulated by the above theory method. PMID:19081188

  14. Optimization of sensing time and cooperative user allocation for OR-rule cooperative spectrum sensing in cognitive radio network

    Institute of Scientific and Technical Information of China (English)

    刘鑫; 仲伟志; 陈琨奇

    2015-01-01

    In order to improve the throughput of cognitive radio (CR), optimization of sensing time and cooperative user allocation for OR-rule cooperative spectrum sensing was investigated in a CR network that includes multiple users and one fusion center. The frame structure of cooperative spectrum sensing was divided into multiple transmission time slots and one sensing time slot consisting of local energy detection and cooperative overhead. An optimization problem was formulated to maximize the throughput of CR network, subject to the constraints of both false alarm probability and detection probability. A joint optimization algorithm of sensing time and number of users was proposed to solve this optimization problem with low time complexity. An allocation algorithm of cooperative users was proposed to preferentially allocate the users to the channels with high utilization probability. The simulation results show that the significant improvement on the throughput can be achieved through the proposed joint optimization and allocation algorithms.

  15. Research on the time optimization model algorithm of Customer Collaborative Product Innovation

    Directory of Open Access Journals (Sweden)

    Guodong Yu

    2014-01-01

    Full Text Available Purpose: To improve the efficiency of information sharing among the innovation agents of customer collaborative product innovation and shorten the product design cycle, an improved genetic annealing algorithm of the time optimization was presented. Design/methodology/approach: Based on the analysis of the objective relationship between the design tasks, the paper takes job shop problems for machining model and proposes the improved genetic algorithm to solve the problems, which is based on the niche technology and thus a better product collaborative innovation design time schedule is got to improve the efficiency. Finally, through the collaborative innovation design of a certain type of mobile phone, the proposed model and method were verified to be correct and effective. Findings and Originality/value: An algorithm with obvious advantages in terms of searching capability and optimization efficiency of customer collaborative product innovation was proposed. According to the defects of the traditional genetic annealing algorithm, the niche genetic annealing algorithm was presented. Firstly, it avoided the effective gene deletions at the early search stage and guaranteed the diversity of solution; Secondly, adaptive double point crossover and swap mutation strategy were introduced to overcome the defects of long solving process and easily converging local minimum value due to the fixed crossover and mutation probability; Thirdly, elite reserved strategy was imported that optimal solution missing was avoided effectively and evolution speed was accelerated. Originality/value: Firstly, the improved genetic simulated annealing algorithm overcomes some defects such as effective gene easily lost in early search. It is helpful to shorten the calculation process and improve the accuracy of the convergence value. Moreover, it speeds up the evolution and ensures the reliability of the optimal solution. Meanwhile, it has obvious advantages in efficiency of

  16. Improving maternal confidence in neonatal care through a checklist intervention.

    Science.gov (United States)

    Radenkovic, Dina; Kotecha, Shrinal; Patel, Shreena; Lakhani, Anjali; Reimann-Dubbers, Katharina; Shah, Shreya; Jafree, Daniyal; Mitrasinovic, Stefan; Whitten, Melissa

    2016-01-01

    Previous qualitative studies suggest a lack of maternal confidence in care of their newborn child upon discharge into the community. This observation was supported by discussion with healthcare professionals and mothers at University College London Hospital (UCLH), highlighting specific areas of concern, in particular identifying and managing common neonatal presentations. The aim of this study was to design and introduce a checklist, addressing concerns, to increase maternal confidence in care of their newborn child. Based on market research, an 8-question checklist was designed, assessing maternal confidence in: feeding, jaundice, nappy care, rashes and dry skin, umbilical cord care, choking, bowel movements, and vomiting. Mothers were assessed as per the checklist, and received a score representative of their confidence in neonatal care. Mothers were followed up with a telephone call, and were assessed after a 7-day-period. Checklist scores before as compared to after the follow-up period were analysed. This process was repeated for three study cycles, with the placement of information posters on the ward prior to the second study cycle, and the stapling of the checklist to the mother's personal child health record (PCHR) prior to the third study cycle. A total of 99 mothers on the Maternity Care Unit at UCLH were enrolled in the study, and 92 were contactable after a 7-day period. During all study cycles, a significant increase in median checklist score was observed after, as compared to before, the 7-day follow up period (p < 0.001). The median difference in checklist score from baseline was greatest for the third cycle. These results suggest that introduction of a simple checklist can be successfully utilised to improve confidence of mothers in being able to care for their newborn child. Further investigation is indicated, but this intervention has the potential for routine application in postnatal care. PMID:27335642

  17. Predicting Natural and Chaotic Time Series with a Swarm-Optimized Neural Network

    Institute of Scientific and Technical Information of China (English)

    Juan A. Lazzús

    2011-01-01

    Natural and chaotic time series are predicted using an artificial neural network (ANN) based on particle swarm optimization (PSO).Firstly,the hybrid ANN+PSO algorithm is applied on Mackey-Glass series in the short-term prediction x(t + 6),using the current value x(t) and the past values:x(t - 6),x(t - 12),x(t - 18).Then,this method is applied on solar radiation data using the values of the past years:x(t - 1),...,x(t - 4).The results show that the ANN+PSO method is a very powerful tool for making predictions of natural and chaotic time series.Chaotic time series is an important research and application area.Several models for time series data can have many forms and represent different stochastic processes.Time series contain much information about dynamic systems.[1] These systems are usually modeled by delay-differential equations.[2]%Natural and chaotic time series are predicted using an artificial neural network (ANN) based on particle swarm optimization (PSO). Firstly, the hybrid ANN+PSO algorithm is applied on Mackey-Glass series in the short-term prediction x(t + 6), using the current value x(t) and the past values: x(t - 6), x(t - 12), x(t - 18). Then, this method is applied on solar radiation data using the values of the past years: x(t - 1), ..., x(t - 4). The results show that the ANN+PSO method is a very powerful tool for making predictions of natural and chaotic time series.

  18. Utility of action checklists as a consensus building tool.

    Science.gov (United States)

    Kim, Yeon-Ha; Yoshikawa, Etsuko; Yoshikawa, Toru; Kogi, Kazutaka; Jung, Moon-Hee

    2015-01-01

    The present study's objective was to determine the mechanisms for enhancing the utility of action checklists applied in participatory approach programs for workplace improvements, to identify the benefits of building consensus and to compare their applicability in Asian countries to find the most appropriate configuration for action checklists. Data were collected from eight trainees and 43 trainers with experience in Participatory Action-Oriented Training. Statistical analysis was performed in SPSS using the package PASW, version 19.0. The difference in the mean score for the degree of the utility of action checklists between countries was analyzed using ANOVA methods. Factor analysis was performed to validate the action checklists' utility. Pearson Correlation Coefficients were then calculated to determine the direction and strength of the relationship between these factors. Using responses obtained from trainees' in-depth interviews, we identified 33 key statements that were then classified into 11 thematic clusters. Five factors were extracted, namely "ease of application", "practical solutions", "group interaction", "multifaceted perspective" and "active involvement". The action checklist was useful for facilitating a participatory process among trainees and trainers for improving working conditions. Action checklists showed similar patterns of utility in various Asian countries; particularly when adjusted to local conditions.

  19. Heuristic Evaluation on Mobile Interfaces: A New Checklist

    Directory of Open Access Journals (Sweden)

    Rosa Yáñez Gómez

    2014-01-01

    Full Text Available The rapid evolution and adoption of mobile devices raise new usability challenges, given their limitations (in screen size, battery life, etc. as well as the specific requirements of this new interaction. Traditional evaluation techniques need to be adapted in order for these requirements to be met. Heuristic evaluation (HE, an Inspection Method based on evaluation conducted by experts over a real system or prototype, is based on checklists which are desktop-centred and do not adequately detect mobile-specific usability issues. In this paper, we propose a compilation of heuristic evaluation checklists taken from the existing bibliography but readapted to new mobile interfaces. Selecting and rearranging these heuristic guidelines offer a tool which works well not just for evaluation but also as a best-practices checklist. The result is a comprehensive checklist which is experimentally evaluated as a design tool. This experimental evaluation involved two software engineers without any specific knowledge about usability, a group of ten users who compared the usability of a first prototype designed without our heuristics, and a second one after applying the proposed checklist. The results of this experiment show the usefulness of the proposed checklist for avoiding usability gaps even with nontrained developers.

  20. Utility of action checklists as a consensus building tool.

    Science.gov (United States)

    Kim, Yeon-Ha; Yoshikawa, Etsuko; Yoshikawa, Toru; Kogi, Kazutaka; Jung, Moon-Hee

    2015-01-01

    The present study's objective was to determine the mechanisms for enhancing the utility of action checklists applied in participatory approach programs for workplace improvements, to identify the benefits of building consensus and to compare their applicability in Asian countries to find the most appropriate configuration for action checklists. Data were collected from eight trainees and 43 trainers with experience in Participatory Action-Oriented Training. Statistical analysis was performed in SPSS using the package PASW, version 19.0. The difference in the mean score for the degree of the utility of action checklists between countries was analyzed using ANOVA methods. Factor analysis was performed to validate the action checklists' utility. Pearson Correlation Coefficients were then calculated to determine the direction and strength of the relationship between these factors. Using responses obtained from trainees' in-depth interviews, we identified 33 key statements that were then classified into 11 thematic clusters. Five factors were extracted, namely "ease of application", "practical solutions", "group interaction", "multifaceted perspective" and "active involvement". The action checklist was useful for facilitating a participatory process among trainees and trainers for improving working conditions. Action checklists showed similar patterns of utility in various Asian countries; particularly when adjusted to local conditions. PMID:25224334

  1. Optimal Configuration for Relaxation Times Estimation in Complex Spin Echo Imaging

    Directory of Open Access Journals (Sweden)

    Fabio Baselice

    2014-01-01

    Full Text Available Many pathologies can be identified by evaluating differences raised in the physical parameters of involved tissues. In a Magnetic Resonance Imaging (MRI framework, spin-lattice T1 and spin-spin T2 relaxation time parameters play a major role in such an identification. In this manuscript, a theoretical study related to the evaluation of the achievable performances in the estimation of relaxation times in MRI is proposed. After a discussion about the considered acquisition model, an analysis on the ideal imaging acquisition parameters in the case of spin echo sequences, i.e., echo and repetition times, is conducted. In particular, the aim of the manuscript consists in providing an empirical rule for optimal imaging parameter identification with respect to the tissues under investigation. Theoretical results are validated on different datasets in order to show the effectiveness of the presented study and of the proposed methodology.

  2. Approximately optimal tracking control for discrete time-delay systems with disturbances

    Institute of Scientific and Technical Information of China (English)

    Gongyou Tang; Huiying Sun; Haiping Pang

    2008-01-01

    Optimal tracking control (OTC) for discrete time-delay systems affected by persistent disturbances with quadratic performance index is considered. By introducing a sensitivity parameter, the original OTC problem is transformed into a series of two-point boundary value (TPBV) problems without time-advance or time-delay terms. The obtained OTC law consists of analytic feedforward and feedback terms and a compensation term which is the sum of an infinite series of adjoint vectors. The analytic feedforward and feedback terms can be found by solving a Riccati matrix equation and two Stein matrix equations. The compensation term can be obtained by using an iteration formula of the adjoint vectors. Observers are constructed to make the approximate OTC law physically realizable. A simulation example shows that the approximate approach is effective in tracking the reference input and robust with respect to exogenous persistent disturbances.

  3. Optimal batch production strategies under continuous price decrease and time discounting

    Directory of Open Access Journals (Sweden)

    Mandal S.

    2007-01-01

    Full Text Available Single price discount in unit cost for bulk purchasing is quite common in reality as well as in inventory literature. However, in today's high-tech industries such as personal computers and mobile industries, continuous decrease in unit cost is a regular phenomenon. In the present paper, an attempt has been made to investigate the effects of continuous price decrease and time-value of money on optimal decisions for inventoried goods having time-dependent demand and production rates. The proposed models are developed over a finite time horizon considering both shortages and without shortages in inventory. Numerical examples are taken to illustrate the developed models and to examine the sensitivity of model parameters.

  4. Energy-Aware Real-Time Task Scheduling for Heterogeneous Multiprocessors with Particle Swarm Optimization Algorithm

    Directory of Open Access Journals (Sweden)

    Weizhe Zhang

    2014-01-01

    Full Text Available Energy consumption in computer systems has become a more and more important issue. High energy consumption has already damaged the environment to some extent, especially in heterogeneous multiprocessors. In this paper, we first formulate and describe the energy-aware real-time task scheduling problem in heterogeneous multiprocessors. Then we propose a particle swarm optimization (PSO based algorithm, which can successfully reduce the energy cost and the time for searching feasible solutions. Experimental results show that the PSO-based energy-aware metaheuristic uses 40%–50% less energy than the GA-based and SFLA-based algorithms and spends 10% less time than the SFLA-based algorithm in finding the solutions. Besides, it can also find 19% more feasible solutions than the SFLA-based algorithm.

  5. The optimal time of day for training during Ramadan: A review study

    Directory of Open Access Journals (Sweden)

    Hamdi Chtourou

    2014-04-01

    Full Text Available Literature concerning the effects of Ramadan fasting on sports performance presents conflicting results. In this context, some studies reported a significant impairment of sports performance during the month of Ramadan. However, other studies suggested that Ramadan fasting has no significant effect on physical performance.  The discrepancies between the studies could be explained by time-of-day variations in testing. In this regard, recent studies reported that Ramadan negatively affects the afternoon sports performance; however, the morning and the evening (after breaking the fast performances were not affected by fasting. This suggests that the optimal time of day for training during Ramadan is the morning or the evening. Therefore, coaches should schedule the training sessions in the morning or evening during the month of Ramadan. However, further studies should investigate the effect of training at a specific time of day on sports performance during Ramadan.

  6. The Optimal Time of Day for Training during Ramadan: A Review Study

    Directory of Open Access Journals (Sweden)

    Hamdi Chtourou

    2014-03-01

    Full Text Available Literature concerning the effects of Ramadan fasting on sports performance presents conflicting results. In this context, some studies reported a significant impairment of sports performance during the month of Ramadan. However, other studies suggested that Ramadan fasting has no significant effect on physical performance. The discrepancies between the studies could be explained by time-of-day variations in testing. In this regard, recent studies reported that Ramadan negatively affects the afternoon sports performance; however, the morning and the evening (after breaking the fast performances were not affected by fasting. This suggests that the optimal time of day for training during Ramadan is the morning or the evening. Therefore, coaches should schedule the training sessions in the morning or evening during the month of Ramadan. However, further studies should investigate the effect of training at a specific time of day on sports performance during Ramadan.

  7. Towards optimal explicit time-stepping schemes for the gyrokinetic equations

    CERN Document Server

    Doerk, H

    2014-01-01

    The nonlinear gyrokinetic equations describe plasma turbulence in laboratory and astrophysical plasmas. To solve these equations, massively parallel codes have been developed and run on present-day supercomputers. This paper describes measures to improve the efficiency of such computations, thereby making them more realistic. Explicit Runge-Kutta schemes are considered to be well suited for time-stepping. Although the numerical algorithms are often highly optimized, performance can still be improved by a suitable choice of the time-stepping scheme, based on spectral analysis of the underlying operator. Here, an operator splitting technique is introduced to combine first-order Runge-Kutta-Chebychev schemes for the collision term with fourth-order schemes for the remaining terms. In the nonlinear regime, based on the observation of eigenvalue shifts due to the (generalized) $E\\times B$ advection term, an accurate and robust estimate for the nonlinear timestep is developed. The presented techniques can reduce si...

  8. Nitrogen and phosphorus changes and optimal drainage time of flooded paddy field based on environmental factors

    Directory of Open Access Journals (Sweden)

    Meng-hua XIAO

    2013-04-01

    Full Text Available While many controlled irrigation and drainage techniques have been adopted in China, the environmental effects of these techniques require further investigation. This study was conducted to examine the changes of nitrogen and phosphorus of a flooded paddy water system after fertilizer application and at each growth stage so as to obtain the optimal drainage time at each growth stage. Four treatments with different water level management methods at each growth stage were conducted under the condition of ten-day continuous flooding. Results show that the ammonia nitrogen (NO3--N concentration reached the peak value once the fertilizer was applied, and then decreased to a relatively low level seven to ten days later, and that the nitrate nitrogen (NH4+-N concentration gradually rose to its peak value, which appeared later in subsurface water than in surface water. Continuous flooding could effectively reduce the concentrations of NH4+-N, NO3--N, and total phosphorus (TP in surface water. However, the paddy water disturbance, in the process of soil surface adsorption and nitrification, caused NH4+-N to be released and increased the concentrations of NH4+-N and NO3--N in surface water. A multi-objective controlled drainage model based on environmental factors was established in order to obtain the optimal drainage time at each growth stage and better guide the drainage practices of farmers. The optimal times for surface drainage are the fourth, sixth, fifth, and sixth days after flooding at the tillering, jointing-booting, heading-flowering, and milking stages, respectively.

  9. Nitrogen and phosphorus changes and optimal drainage time of flooded paddy field based on environmental factors

    Institute of Scientific and Technical Information of China (English)

    Meng-hua XIAO; Shuang-en YU; Yan-yan WANG; Rong HUANG

    2013-01-01

    While many controlled irrigation and drainage techniques have been adopted in China, the environmental effects of these techniques require further investigation. This study was conducted to examine the changes of nitrogen and phosphorus of a flooded paddy water system after fertilizer application and at each growth stage so as to obtain the optimal drainage time at each growth stage. Four treatments with different water level management methods at each growth stage were conducted under the condition of ten-day continuous flooding. Results show that the ammonia nitrogen ( NH -N+ ) concentration reached the peak value once the fertilizer was applied, and then 4 decreased to a relatively low level seven to ten days later, and that the nitrate nitrogen ( NO -N− ) 3 concentration gradually rose to its peak value, which appeared later in subsurface water than in surface water. Continuous flooding could effectively reduce the concentrations of NH -N+ , 4 NO -N− , and total phosphorus (TP) in surface water. However, the paddy water disturbance, in the process of soil surface adsorption and nitrification, caused 3 NH -N+ to be released and increased the 4 concentrations of NH -N+ and 4 NO -N− in surface water. A multi-objective controlled drainage 3 model based on environmental factors was established in order to obtain the optimal drainage time at each growth stage and better guide the drainage practices of farmers. The optimal times for surface drainage are the fourth, sixth, fifth, and sixth days after flooding at the tillering, jointing-booting, heading-flowering, and milking stages, respectively.

  10. RTRO–Coal: Real-Time Resource-Reconciliation and Optimization for Exploitation of Coal Deposits

    Directory of Open Access Journals (Sweden)

    Jörg Benndorf

    2015-08-01

    Full Text Available This contribution presents an innovative and integrated framework for real-time-process reconciliation and optimization (RTRO in large continuous open pit coal mines. RTRO-Coal is currently developed, validated, tested and implemented as part of a multi-national multi-partner European Union funded R&D project. The key concept is to promote a shift in paradigm from intermittent discontinuous to a continuous process monitoring and quality management system in large scale coal mining operations. The framework is based on a real-time feedback control loop linking online data acquired during extraction rapidly with a sequentially up-datable resource model. The up-to-date model is integrated with a real-time optimization of short-term sequencing and production control decisions. Improved decisions are expected to lead to increased resource-and process efficiency and support a sustainable extraction of natural resources. This contribution introduces to the framework, discusses main building blocks and illustrates the value added by the means of selected examples.

  11. Grey-Theory-Based Optimization Model of Emergency Logistics Considering Time Uncertainty.

    Science.gov (United States)

    Qiu, Bao-Jian; Zhang, Jiang-Hua; Qi, Yuan-Tao; Liu, Yang

    2015-01-01

    Natural disasters occur frequently in recent years, causing huge casualties and property losses. Nowadays, people pay more and more attention to the emergency logistics problems. This paper studies the emergency logistics problem with multi-center, multi-commodity, and single-affected-point. Considering that the path near the disaster point may be damaged, the information of the state of the paths is not complete, and the travel time is uncertainty, we establish the nonlinear programming model that objective function is the maximization of time-satisfaction degree. To overcome these drawbacks: the incomplete information and uncertain time, this paper firstly evaluates the multiple roads of transportation network based on grey theory and selects the reliable and optimal path. Then simplify the original model under the scenario that the vehicle only follows the optimal path from the emergency logistics center to the affected point, and use Lingo software to solve it. The numerical experiments are presented to show the feasibility and effectiveness of the proposed method.

  12. Self-organization of laterally asymmetrical movements as a consequence of space-time optimization.

    Science.gov (United States)

    Mangalam, Madhur; Desai, Nisarg; Singh, Mewa

    2016-02-01

    Laterally asymmetrical movements are ubiquitous among organisms. A bilaterally symmetrical organism cannot maneuver through a two- or three-dimensional space unless and until one side of its body leads, because the forces that cause the movements of the body are generated within the body. One question follows: are there any costs or benefits of laterally asymmetrical movements? We test whether directionally consistent laterally asymmetrical movements at different levels of organization of movements (at the individual, and not the population level) can work synergistically. We show-by means of a hypothetical system resembling a humanoid robot-that a laterally asymmetrical movement at a lower level of organization of movements can stimulate laterally asymmetrical movements that are directionally consistent at consecutive higher levels. We show-by comparing two hypothetical systems, incorporating laterally symmetrical and asymmetrical movements, respectively-that the asymmetrical system outperforms the symmetrical system by optimizing space and time and that this space-time advantage increases with the increasing complexity of the task. Together, these results suggest that laterally asymmetrical movements can self-organize as a consequence of space-time optimization. PMID:26620631

  13. Optimal time of soybean seed priming and primer effect under salt stress conditions

    Directory of Open Access Journals (Sweden)

    Miladinov Zlatica J.

    2015-01-01

    Full Text Available The aim of this study was to examine optimal time of soybean seed priming and effect of primers under salt stress conditions. Testing was performed at the Institute of Field and Vegetable Crops, Novi Sad, on Galina seed variety. Optimal priming time was determined by immersing seed into: KNO3 (1%, H2O2 (0.1%, and H2O with the duration of 6 h, 12 h, 18 h, and 24 h. After drying until the initial moisture, the seed was placed for germination and after eight days germination was determined. In the second part of the experiment, the seed was immersed into: KNO3 (1%, H2O2 (0,1%, and H2O after which their effect on germination energy and seed germination under simulated salinity conditions was examined. Simulated salinity conditions represented substrate for germination to which NaCl in different concentrations was added (0, 50, 100, 150, 200 mM. Results of the research showed that the six-hour priming of seed was the best with all primers. The percentage of seed germination linearly reduced with the increase of priming time. The research has shown that seed priming represents a favorable technique for the reduction of a negative effect of NaCl on germination energy and soybean seed germination, and the best effect is accomplished with the use of KNO3.

  14. Grey-Theory-Based Optimization Model of Emergency Logistics Considering Time Uncertainty.

    Directory of Open Access Journals (Sweden)

    Bao-Jian Qiu

    Full Text Available Natural disasters occur frequently in recent years, causing huge casualties and property losses. Nowadays, people pay more and more attention to the emergency logistics problems. This paper studies the emergency logistics problem with multi-center, multi-commodity, and single-affected-point. Considering that the path near the disaster point may be damaged, the information of the state of the paths is not complete, and the travel time is uncertainty, we establish the nonlinear programming model that objective function is the maximization of time-satisfaction degree. To overcome these drawbacks: the incomplete information and uncertain time, this paper firstly evaluates the multiple roads of transportation network based on grey theory and selects the reliable and optimal path. Then simplify the original model under the scenario that the vehicle only follows the optimal path from the emergency logistics center to the affected point, and use Lingo software to solve it. The numerical experiments are presented to show the feasibility and effectiveness of the proposed method.

  15. Optimal Decision for Fashion Supply Chains with Service Level Constraint and Controllable Lead Time

    Directory of Open Access Journals (Sweden)

    Guo Li

    2015-01-01

    Full Text Available We study a two-echelon supply chain inventory model with controllable lead time and service level constraint in fashion supply chains, in which we assume that the unit cost of compressing lead time follows exponential distribution. Under these conditions we investigate the optimal ordering quantity and production quantity in the fashion supply chain by minimizing the joint total cost. Simultaneously, we work out the boundaries of ordering quantity and production quantity, which simplify the computation. Furthermore, numerical examples are presented to test the feasibility of the model. The results show that assuming the unit cost of compressing lead time in accordance with exponential distribution is realistic. It also notices that the optimal order and production decision for fashion supply chains are constrained obviously by the service level and safety factors. What is more, the holding cost rate of both the service level and safety factors has a certain influence on it. And by further analyzing on some references in the last part, we have done some extensions and found some interesting results.

  16. Cognitive Aging and Time Perception: Roles of Bayesian Optimization and Degeneracy.

    Science.gov (United States)

    Turgeon, Martine; Lustig, Cindy; Meck, Warren H

    2016-01-01

    This review outlines the basic psychological and neurobiological processes associated with age-related distortions in timing and time perception in the hundredths of milliseconds-to-minutes range. The difficulty in separating indirect effects of impairments in attention and memory from direct effects on timing mechanisms is addressed. The main premise is that normal aging is commonly associated with increased noise and temporal uncertainty as a result of impairments in attention and memory as well as the possible reduction in the accuracy and precision of a central timing mechanism supported by dopamine-glutamate interactions in cortico-striatal circuits. Pertinent to these findings, potential interventions that may reduce the likelihood of observing age-related declines in timing are discussed. Bayesian optimization models are able to account for the adaptive changes observed in time perception by assuming that older adults are more likely to base their temporal judgments on statistical inferences derived from multiple trials than on a single trial's clock reading, which is more susceptible to distortion. We propose that the timing functions assigned to the age-sensitive fronto-striatal network can be subserved by other neural networks typically associated with finely-tuned perceptuo-motor adjustments, through degeneracy principles (different structures serving a common function). PMID:27242513

  17. The L_infinity constrained global optimal histogram equalization technique for real time imaging

    Science.gov (United States)

    Ren, Qiongwei; Niu, Yi; Liu, Lin; Jiao, Yang; Shi, Guangming

    2015-08-01

    Although the current imaging sensors can achieve 12 or higher precision, the current display devices and the commonly used digital image formats are still only 8 bits. This mismatch causes significant waste of the sensor precision and loss of information when storing and displaying the images. For better usage of the precision-budget, tone mapping operators have to be used to map the high-precision data into low-precision digital images adaptively. In this paper, the classic histogram equalization tone mapping operator is reexamined in the sense of optimization. We point out that the traditional histogram equalization technique and its variants are fundamentally improper by suffering from local optimum problems. To overcome this drawback, we remodel the histogram equalization tone mapping task based on graphic theory which achieves the global optimal solutions. Another advantage of the graphic-based modeling is that the tone-continuity is also modeled as a vital constraint in our approach which suppress the annoying boundary artifacts of the traditional approaches. In addition, we propose a novel dynamic programming technique to solve the histogram equalization problem in real time. Experimental results shows that the proposed tone-preserved global optimal histogram equalization technique outperforms the traditional approaches by exhibiting more subtle details in the foreground while preserving the smoothness of the background.

  18. System for Road Vehicle Energy Optimization Using Real Time Road and Traffic Information

    OpenAIRE

    Felipe Jiménez; Wilmar Cabrera-Montiel

    2014-01-01

    Nowadays, reducing the energy and fuel consumption of road vehicles is a key issue. Different strategies have been proposed. One of them is to promote Eco-driving behaviour among drivers. Most Eco-driving tips take into account only the road stretch where the vehicle is located. However, larger improvements could be achieved if information from subsequent stretches is used. The main objective of this work is to develop a system to warn the driver in real time of the optimal speed that should ...

  19. Mathematical optimization of variable valve timing for reducing fuel consumption of A SI engine

    OpenAIRE

    Kakaee, Amir-Hasan; Keshavarz, Mehdi; Paykani, Amin; Keshavarz, Mohaamad

    2016-01-01

    In this study, the sensitivity analysis and Quasi-Newton algorithms are used to optimize valve timing XU7/L3 engine in order to reduce fuel consumption and increase engine performance. At first, all components of engine are modeled in GT-POWER and a comparison with experimental results is performed to confirm the accuracy of the model. Then, GT-POWER model is coupled with MATLAB-SIMULINK to control inputs and outputs with sensitivity analysis and Quasi-Newton algorithms. The results obtained ...

  20. Manufacturing Supply Chain Optimization Problem with Time Windows Based on Improved Orthogonal Genetic Algorithm

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xinhua

    2006-01-01

    Aim to the manufacturing supply chain optimization problem with time windows, presents an improved orthogonal genetic algorithm to solve it. At first, we decompose this problem into two sub-problems (distribution and routing) plus an interface mechanism to allow the two algorithms to collaborate in a master-slave fashion, with the distribution algorithm driving the routing algorithm. At second, we describe the proposed improved orthogonal genetic algorithm for solving giving problem detailedly. Finally, the examples suggest that this proposed approach is feasible, correct and valid.

  1. Optimal operation strategy of battery energy storage system to real-time electricity price in Denmark

    DEFF Research Database (Denmark)

    Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte

    2010-01-01

    Since the hourly spot market price is available one day ahead, the price could be transferred to the consumers and they may have some motivations to install an energy storage system in order to save their energy costs. This paper presents an optimal operation strategy for a battery energy storage...... system (BESS) in relation to the real-time electricity price in order to achieve the maximum profits of the BESS. The western Danish power system, which is currently the grid area in the world that has the largest share of wind power in its generation profiles and may represent the future of electricity...

  2. Optimal State Estimation for Discrete-Time Markov Jump Systems with Missing Observations

    Directory of Open Access Journals (Sweden)

    Qing Sun

    2014-01-01

    Full Text Available This paper is concerned with the optimal linear estimation for a class of direct-time Markov jump systems with missing observations. An observer-based approach of fault detection and isolation (FDI is investigated as a detection mechanic of fault case. For systems with known information, a conditional prediction of observations is applied and fault observations are replaced and isolated; then, an FDI linear minimum mean square error estimation (LMMSE can be developed by comprehensive utilizing of the correct information offered by systems. A recursive equation of filtering based on the geometric arguments can be obtained. Meanwhile, a stability of the state estimator will be guaranteed under appropriate assumption.

  3. Approximate analytical solution of diffusion equation with fractional time derivative using optimal homotopy analysis method

    Directory of Open Access Journals (Sweden)

    S. Das

    2013-12-01

    Full Text Available In this article, optimal homotopy-analysis method is used to obtain approximate analytic solution of the time-fractional diffusion equation with a given initial condition. The fractional derivatives are considered in the Caputo sense. Unlike usual Homotopy analysis method, this method contains at the most three convergence control parameters which describe the faster convergence of the solution. Effects of parameters on the convergence of the approximate series solution by minimizing the averaged residual error with the proper choices of parameters are calculated numerically and presented through graphs and tables for different particular cases.

  4. Optimal time point for the transplantation of neural stem cells induced to differentiate with retinoic acid

    Institute of Scientific and Technical Information of China (English)

    Shuxin Wang; Dengji Pan; Na Liu; Yongming Liu; Juan Chen; Houjie Ni; Zhouping Tang

    2011-01-01

    Previous studies have demonstrated that differentiated neural stem cells (NSCs) are more suitable for transplantation than non-differentiated NSCs. In this study, NSCs were expanded in vitro for two passages, induced with retinoic acid to differentiate, and harvested between 1-6 days later. They were subsequently cultured in artificial cerebrospinal fluid for an additional 3 days, during which their growth and morphology was monitored. NSCs induced for 4 days exhibited a peak rate of cells differentiating into neurons and robust growth. Our results indicate that the optimal time point for transplanting NSCs is following a 4-day period of induced differentiation.

  5. Optimizing Real-Time Performance of 3D Virtual Mining Environment with MultiGen Creator

    Institute of Scientific and Technical Information of China (English)

    WANGWei-chen; JIANGXiao-hong; HANKe-qi; HANWen-ji

    2004-01-01

    System optimization plays a crucial role in developing VR system after 3D modeling, affecting the system's Immersion and Interaction performance enormously. In this article, several key techniques of optimizing a virtual mining system were discussed: optimizing 3D models to keep the polygon number in VR system within target hardware's processing ability;optimizing texture database to save texture memory with perfect visual effect; optimizing database hierarchy structure to accelerate model retrieval; and optimizing LOD hierarchy structure to speed up rendering~

  6. Variational data assimilation for the optimized ozone initial state and the short-time forecasting

    Science.gov (United States)

    Park, Soon-Young; Kim, Dong-Hyeok; Lee, Soon-Hwan; Lee, Hwa Woon

    2016-04-01

    In this study, we apply the four-dimensional variational (4D-Var) data assimilation to optimize initial ozone state and to improve the predictability of air quality. The numerical modeling systems used for simulations of atmospheric condition and chemical formation are the Weather Research and Forecasting (WRF) model and the Community Multiscale Air Quality (CMAQ) model . The study area covers the capital region of South Korea, where the surface measurement sites are relatively evenly distributed. The 4D-Var code previously developed for the CMAQ model is modified to consider background error in matrix form, and various numerical tests are conducted. The results are evaluated with an idealized covariance function for the appropriateness of the modified codes. The background error is then constructed using the NMC method with long-term modeling results, and the characteristics of the spatial correlation scale related to local circulation is analyzed. The background error is applied in the 4D-Var research, and a surface observational assimilation is conducted to optimize the initial concentration of ozone. The statistical results for the 12-hour assimilation periods and the 120 observatory sites show a 49.4% decrease in the root mean squred error (RMSE), and a 59.9% increase in the index of agreement (IOA). The temporal variation of spatial distribution of the analysis increments indicates that the optimized initial state of ozone concentration is transported to inland areas by the clockwise-rotating local circulation during the assimilation windows. To investigate the predictability of ozone concentration after the assimilation window, a short-time forecasting is carried out. The ratios of the RMSE with assimilation versus that without assimilation are 8% and 13% for the +24 and +12 hours, respectively. Such a significant improvement in the forecast accuracy is obtained solely by using the optimized initial state. The potential improvement in ozone prediction for

  7. Updated Checklist of the Mosquitoes (Diptera: Culicidae) of French Guiana.

    Science.gov (United States)

    Talaga, Stanislas; Dejean, Alain; Carinci, Romuald; Gaborit, Pascal; Dusfour, Isabelle; Girod, Romain

    2015-09-01

    The incredible mosquito species diversity in the Neotropics can provoke major confusion during vector control programs when precise identification is needed. This is especially true in French Guiana where studies on mosquito diversity practically ceased 35 yr ago. In order to fill this gap, we propose here an updated and comprehensive checklist of the mosquitoes of French Guiana, reflecting the latest changes in classification and geographical distribution and the recognition of current or erroneous synonymies. This work was undertaken in order to help ongoing and future research on mosquitoes in a broad range of disciplines such as ecology, biogeography, and medical entomology. Thirty-two valid species cited in older lists have been removed, and 24 species have been added including 12 species (comprising two new genera and three new subgenera) reported from French Guiana for the first time. New records are from collections conducted on various phytotelmata in French Guiana and include the following species: Onirion sp. cf Harbach and Peyton (2000), Sabethes (Peytonulus) hadrognathus Harbach, Sabethes (Peytonulus) paradoxus Harbach, Sabethes (Peytonulus) soperi Lane and Cerqueira, Sabethes (Sabethinus) idiogenes Harbach, Sabethes (Sabethes) quasicyaneus Peryassú, Runchomyia (Ctenogoeldia) magna (Theobald), Wyeomyia (Caenomyiella) sp. cf Harbach and Peyton (1990), Wyeomyia (Dendromyia) ypsipola Dyar, Wyeomyia (Hystatomyia) lamellata (Bonne-Wepster and Bonne), Wyeomyia (Miamyia) oblita (Lutz), and Toxorhynchites (Lynchiella) guadeloupensis (Dyar and Knab). At this time, the mosquitoes of French Guiana are represented by 235 species distributed across 22 genera, nine tribes, and two subfamilies.

  8. Performance deterioration modeling and optimal preventive maintenance strategy under scheduled servicing subject to mission time

    Institute of Scientific and Technical Information of China (English)

    Li Dawei; Zhang Zhihua; Zhong Qianghui; Zhai Yali

    2014-01-01

    Servicing is applied periodically in practice with the aim of restoring the system state and prolonging the lifetime. It is generally seen as an imperfect maintenance action which has a chief influ-ence on the maintenance strategy. In order to model the maintenance effect of servicing, this study analyzes the deterioration characteristics of system under scheduled servicing. And then the deterio-ration model is established from the failure mechanism by compound Poisson process. On the basis of the system damage value and failure mechanism, the failure rate refresh factor is proposed to describe the maintenance effect of servicing. A maintenance strategy is developed which combines the benefits of scheduled servicing and preventive maintenance. Then the optimization model is given to determine the optimal servicing period and preventive maintenance time, with an objective to minimize the sys-tem expected life-cycle cost per unit time and a constraint on system survival probability for the dura-tion of mission time. Subject to mission time, it can control the ability of accomplishing the mission at any time so as to ensure the high dependability. An example of water pump rotor relating to scheduled servicing is introduced to illustrate the failure rate refresh factor and the proposed maintenance strat-egy. Compared with traditional methods, the numerical results show that the failure rate refresh factor can describe the maintenance effect of servicing more intuitively and objectively. It also demonstrates that this maintenance strategy can prolong the lifetime, reduce the total lifetime maintenance cost and guarantee the dependability of system.

  9. Measurement Properties and Implementation of a Checklist to Assess Leadership Skills during Interdisciplinary Rounds in the Intensive Care Unit

    OpenAIRE

    Ten Have, Elsbeth C. M.; Nap, Raoul E; Tulleken, Jaap E.

    2015-01-01

    The implementation of interdisciplinary teams in the intensive care unit (ICU) has focused attention on leadership behavior. A daily recurrent situation in ICUs in which both leadership behavior and interdisciplinary teamwork are integrated concerns the interdisciplinary rounds (IDRs). Although IDRs are recommended to provide optimal interdisciplinary and patient-centered care, there are no checklists available for leading physicians. We tested the measurement properties and implementation of...

  10. A methodology to quantify and optimize time complementarity between hydropower and solar PV systems

    Science.gov (United States)

    Kougias, Ioannis; Szabó, Sándor; Monforti-Ferrario, Fabio; Huld, Thomas; Bódis, Katalin

    2016-04-01

    Hydropower and solar energy are expected to play a major role in achieving renewable energy sources' (RES) penetration targets. However, the integration of RES in the energy mix needs to overcome the technical challenges that are related to grid's operation. Therefore, there is an increasing need to explore approaches where different RES will operate under a synergetic approach. Ideally, hydropower and solar PV systems can be jointly developed in such systems where their electricity output profiles complement each other as much as possible and minimize the need for reserve capacities and storage costs. A straightforward way to achieve that is by optimizing the complementarity among RES systems both over time and spatially. The present research developed a methodology that quantifies the degree of time complementarity between small-scale hydropower stations and solar PV systems and examines ways to increase it. The methodology analyses high-resolution spatial and temporal data for solar radiation obtained from the existing PVGIS model (available online at: http://re.jrc.ec.europa.eu/pvgis/) and associates it with hydrological information of water inflows to a hydropower station. It builds on an exhaustive optimization algorithm that tests possible alterations of the PV system installation (azimuth, tilt) aiming to increase the complementarity, with minor compromises in the total solar energy output. The methodology has been tested in several case studies and the results indicated variations among regions and different hydraulic regimes. In some cases a small compromise in the solar energy output showed significant increases of the complementarity, while in other cases the effect is not that strong. Our contribution aims to present these findings in detail and initiate a discussion on the role and gains of increased complementarity between solar and hydropower energies. Reference: Kougias I, Szabó S, Monforti-Ferrario F, Huld T, Bódis K (2016). A methodology for

  11. Optimizing the decomposition of soil moisture time-series data using genetic algorithms

    Science.gov (United States)

    Kulkarni, C.; Mengshoel, O. J.; Basak, A.; Schmidt, K. M.

    2015-12-01

    The task of determining near-surface volumetric water content (VWC), using commonly available dielectric sensors (based upon capacitance or frequency domain technology), is made challenging due to the presence of "noise" such as temperature-driven diurnal variations in the recorded data. We analyzed a post-wildfire rainfall and runoff monitoring dataset for hazard studies in Southern California. VWC was measured with EC-5 sensors manufactured by Decagon Devices. Many traditional signal smoothing techniques such as moving averages, splines, and Loess smoothing exist. Unfortunately, when applied to our post-wildfire dataset, these techniques diminish maxima, introduce time shifts, and diminish signal details. A promising seasonal trend-decomposition procedure based on Loess (STL) decomposes VWC time series into trend, seasonality, and remainder components. Unfortunately, STL with its default parameters produces similar results as previously mentioned smoothing methods. We propose a novel method to optimize seasonal decomposition using STL with genetic algorithms. This method successfully reduces "noise" including diurnal variations while preserving maxima, minima, and signal detail. Better decomposition results for the post-wildfire VWC dataset were achieved by optimizing STL's control parameters using genetic algorithms. The genetic algorithms minimize an additive objective function with three weighted terms: (i) root mean squared error (RMSE) of straight line relative to STL trend line; (ii) range of STL remainder; and (iii) variance of STL remainder. Our optimized STL method, combining trend and remainder, provides an improved representation of signal details by preserving maxima and minima as compared to the traditional smoothing techniques for the post-wildfire rainfall and runoff monitoring data. This method identifies short- and long-term VWC seasonality and provides trend and remainder data suitable for forecasting VWC in response to precipitation.

  12. Optimization Based Data Mining Approah for Forecasting Real-Time Energy Demand

    Energy Technology Data Exchange (ETDEWEB)

    Omitaomu, Olufemi A [ORNL; Li, Xueping [University of Tennessee, Knoxville (UTK); Zhou, Shengchao [University of Tennessee, Knoxville (UTK)

    2015-01-01

    The worldwide concern over environmental degradation, increasing pressure on electric utility companies to meet peak energy demand, and the requirement to avoid purchasing power from the real-time energy market are motivating the utility companies to explore new approaches for forecasting energy demand. Until now, most approaches for forecasting energy demand rely on monthly electrical consumption data. The emergence of smart meters data is changing the data space for electric utility companies, and creating opportunities for utility companies to collect and analyze energy consumption data at a much finer temporal resolution of at least 15-minutes interval. While the data granularity provided by smart meters is important, there are still other challenges in forecasting energy demand; these challenges include lack of information about appliances usage and occupants behavior. Consequently, in this paper, we develop an optimization based data mining approach for forecasting real-time energy demand using smart meters data. The objective of our approach is to develop a robust estimation of energy demand without access to these other building and behavior data. Specifically, the forecasting problem is formulated as a quadratic programming problem and solved using the so-called support vector machine (SVM) technique in an online setting. The parameters of the SVM technique are optimized using simulated annealing approach. The proposed approach is applied to hourly smart meters data for several residential customers over several days.

  13. Managing simulation-based training: A framework for optimizing learning, cost, and time

    Science.gov (United States)

    Richmond, Noah Joseph

    This study provides a management framework for optimizing training programs for learning, cost, and time when using simulation based training (SBT) and reality based training (RBT) as resources. Simulation is shown to be an effective means for implementing activity substitution as a way to reduce risk. The risk profile of 22 US Air Force vehicles are calculated, and the potential risk reduction is calculated under the assumption of perfect substitutability of RBT and SBT. Methods are subsequently developed to relax the assumption of perfect substitutability. The transfer effectiveness ratio (TER) concept is defined and modeled as a function of the quality of the simulator used, and the requirements of the activity trained. The Navy F/A-18 is then analyzed in a case study illustrating how learning can be maximized subject to constraints in cost and time, and also subject to the decision maker's preferences for the proportional and absolute use of simulation. Solution methods for optimizing multiple activities across shared resources are next provided. Finally, a simulation strategy including an operations planning program (OPP), an implementation program (IP), an acquisition program (AP), and a pedagogical research program (PRP) is detailed. The study provides the theoretical tools to understand how to leverage SBT, a case study demonstrating these tools' efficacy, and a set of policy recommendations to enable the US military to better utilize SBT in the future.

  14. Physicochemical properties and starch digestibility of Chinese noodles in relation to optimal cooking time.

    Science.gov (United States)

    Ye, Xiaoting; Sui, Zhongquan

    2016-03-01

    Changes in the physicochemical properties and starch digestibility of white salted noodles (WSN) at different cooking stage were investigated. The noodles were dried in fresh air and then cooked for 2-12 min by boiling in distilled water to determine the properties of cooking quality, textural properties and optical characteristic. For starch digestibility, dry noodles were milled and sieved into various particle size classes ranging from 0.5 mm to 5.0 mm, and hydrolyzed by porcine pancreatic α-amylase. The optimal cooking time of WSN determined by squeezing between glasses was 6 min. The results showed that the kinetics of solvation of starch and protein molecules were responsible for changes of the physicochemical properties of WSN during cooking. The susceptibility of starch to α-amylase was influenced by the cooking time, particle size and enzyme treatment. The greater value of rapidly digestible starch (RDS) and lower value of slowly digestible starch (SDS) and resistant starch (RS) were reached at the optimal cooking stage ranging between 63.14-71.97%, 2.47-10.74% and 23.94-26.88%, respectively, indicating the susceptibility on hydrolysis by enzyme was important in defining the cooked stage. The study suggested that cooking quality and digestibility were not correlated but the texture greatly controls the digestibility of the noodles.

  15. Optimal conservation resource allocation under variable economic and ecological time discounting rates in boreal forest.

    Science.gov (United States)

    Mazziotta, Adriano; Pouzols, Federico Montesino; Mönkkönen, Mikko; Kotiaho, Janne S; Strandman, Harri; Moilanen, Atte

    2016-09-15

    Resource allocation to multiple alternative conservation actions is a complex task. A common trade-off occurs between protection of smaller, expensive, high-quality areas versus larger, cheaper, partially degraded areas. We investigate optimal allocation into three actions in boreal forest: current standard forest management rules, setting aside of mature stands, or setting aside of clear-cuts. We first estimated how habitat availability for focal indicator species and economic returns from timber harvesting develop through time as a function of forest type and action chosen. We then developed an optimal resource allocation by accounting for budget size and habitat availability of indicator species in different forest types. We also accounted for the perspective adopted towards sustainability, modeled via temporal preference and economic and ecological time discounting. Controversially, we found that in boreal forest set-aside followed by protection of clear-cuts can become a winning cost-effective strategy when accounting for habitat requirements of multiple species, long planning horizon, and limited budget. It is particularly effective when adopting a long-term sustainability perspective, and accounting for present revenues from timber harvesting. The present analysis assesses the cost-effective conditions to allocate resources into an inexpensive conservation strategy that nevertheless has potential to produce high ecological values in the future. PMID:27262031

  16. Accurate real-time stereo correspondence using intra- and inter-scanline optimization

    Institute of Scientific and Technical Information of China (English)

    Li YAO; Dong-xiao LI; Jing ZHANG; Liang-hao WANG; Ming ZHANG

    2012-01-01

    This paper deals with a novel stereo algorithm that can generate accurate dense disparity maps in real time.The algorithm employs an effective cross-based variable support aggregation strategy within a scanline optimization framework.Rather than matching intensities directly,the use of adaptive support aggregation allows for precisely handling the weak textured regions as well as depth discontinuities.To improve the disparity results with global reasoning,we reformulate the energy function on a tree structure over the whole 2D image area,as opposed to dynamic programming of individual scanlines.By applying both intra-and inter-scanline optimizations,the algorithm reduces the typical ‘streaking' artifact while maintaining high computational efficiency.The experimental results are evaluated on the Middlebury stereo dataset,showing that our approach is among the best for all real-time approaches.We implement the algorithm on a commodity graphics card with CUDA architecture,running at about 35 fames/s for a typical stereo pair with a resolution of 384x288 and 16 disparity levels.

  17. Study on Optimal Grouting Timing for Controlling Uplift Deformation of a Super High Arch Dam

    Science.gov (United States)

    Lin, Peng; Zhu, Xiaoxu; Li, Qingbin; Liu, Hongyuan; Yu, Yongjun

    2016-01-01

    A grouting model is developed for use during the grouting of the complex foundation of a super high arch dam. The purpose as to determine the optimal grouting timing and appropriate grouting pressure involved in controlling the uplift deformation of the dam. The model determines the optimal grouting time as the height of the arch dam increases with the concrete pouring, by checking the tensile stresses in the dam against standard specifications. The appropriate grouting pressures are given on the basis of the actual grouting pressures monitored during the upstream riverbed foundation grouting. An engineering procedure, applying the model, was then proposed and used during foundation grouting under the toe block of the Xiluodu super high-arch dam in south-western China. The quality of the foundation grouting was evaluated against the results from pressurized water permeability tests, acoustic wave velocity tests, elastic modulus tests and panoramic photographing of the rockmass on completion of the foundation grouting. The results indicated that the proposed grouting model can be applied to effectively reduce the uplift deformation and associated cracking risk for super high arch dams, and it can be concluded that the proposed engineering grouting procedure is a valuable tool for improving foundation grouting under the toe blocks of a super high arch dam.

  18. Analytical Framework for Optimizing Weighted Average Download Time in Peer-to-Peer Networks

    CERN Document Server

    Xie, Bike; Wesel, Richard D

    2008-01-01

    This paper proposes an analytical framework for peer-to-peer (P2P) networks and introduces schemes for building P2P networks to approach the minimum weighted average download time (WADT). In the considered P2P framework, the server, which has the information of all the download bandwidths and upload bandwidths of the peers, minimizes the weighted average download time by determining the optimal transmission rate from the server to the peers and from the peers to the other peers. This paper first defines the static P2P network, the hierarchical P2P network and the strictly hierarchical P2P network. Any static P2P network can be decomposed into an equivalent network of sub-peers that is strictly hierarchical. This paper shows that convex optimization can minimize the WADT for P2P networks by equivalently minimizing the WADT for strictly hierarchical networks of sub-peers. This paper then gives an upper bound for minimizing WADT by constructing a hierarchical P2P network, and lower bound by weakening the constra...

  19. Real-Time Vehicle Energy Management System Based on Optimized Distribution of Electrical Load Power

    Directory of Open Access Journals (Sweden)

    Yuefei Wang

    2016-10-01

    Full Text Available As a result of severe environmental pressure and stringent government regulations, refined energy management for vehicles has become inevitable. To improve vehicle fuel economy, this paper presents a bus-based energy management system for the electrical system of internal combustion engine vehicles. Both the model of an intelligent alternator and the model of a lead-acid battery are discussed. According to these models, the energy management for a vehicular electrical system is formulated as a global optimal control problem which aims to minimize fuel consumption. Pontryagin’s minimum principle is applied to solve the optimal control problem to realize a real-time control strategy for electrical energy management in vehicles. The control strategy can change the output of the intelligent alternator and the battery with the changes of electrical load and driving conditions in real-time. Experimental results demonstrate that, compared to the traditional open-loop control strategy, the proposed control strategy for vehicle energy management can effectively reduce fuel consumption and the fuel consumption per 100 km is decreased by approximately 1.7%.

  20. Optimization of the ionization time of an atom with tailored laser pulses: a theoretical study

    CERN Document Server

    Kammerlander, David; Marques, Miguel A L

    2016-01-01

    How fast can a laser pulse ionize an atom? We address this question by considering pulses that carry a fixed time-integrated energy per-area, and finding those that achieve the double requirement of maximizing the ionization that they induce, while having the shortest duration. We formulate this double-objective quantum optimal control problem by making use of the Pareto approach to multi-objetive optimization, and the differential evolution genetic algorithm. The goal is to find out how much a precise time-profiling of ultra-fast, large-bandwidth pulses may speed up the ionization process with respect to simple-shape pulses. We work on a simple one-dimensional model of hydrogen-like atoms (the P\\"oschl-Teller potential), that allows to tune the number of bound states that play a role in the ionization dynamics. We show how the detailed shape of the pulse accelerates the ionization process, and how the presence or absence of bound states influences the velocity of the process.

  1. The LDA beamformer: Optimal estimation of ERP source time series using linear discriminant analysis.

    Science.gov (United States)

    Treder, Matthias S; Porbadnigk, Anne K; Shahbazi Avarvand, Forooz; Müller, Klaus-Robert; Blankertz, Benjamin

    2016-04-01

    We introduce a novel beamforming approach for estimating event-related potential (ERP) source time series based on regularized linear discriminant analysis (LDA). The optimization problems in LDA and linearly-constrained minimum-variance (LCMV) beamformers are formally equivalent. The approaches differ in that, in LCMV beamformers, the spatial patterns are derived from a source model, whereas in an LDA beamformer the spatial patterns are derived directly from the data (i.e., the ERP peak). Using a formal proof and MEG simulations, we show that the LDA beamformer is robust to correlated sources and offers a higher signal-to-noise ratio than the LCMV beamformer and PCA. As an application, we use EEG data from an oddball experiment to show how the LDA beamformer can be harnessed to detect single-trial ERP latencies and estimate connectivity between ERP sources. Concluding, the LDA beamformer optimally reconstructs ERP sources by maximizing the ERP signal-to-noise ratio. Hence, it is a highly suited tool for analyzing ERP source time series, particularly in EEG/MEG studies wherein a source model is not available.

  2. Physicochemical properties and starch digestibility of Chinese noodles in relation to optimal cooking time.

    Science.gov (United States)

    Ye, Xiaoting; Sui, Zhongquan

    2016-03-01

    Changes in the physicochemical properties and starch digestibility of white salted noodles (WSN) at different cooking stage were investigated. The noodles were dried in fresh air and then cooked for 2-12 min by boiling in distilled water to determine the properties of cooking quality, textural properties and optical characteristic. For starch digestibility, dry noodles were milled and sieved into various particle size classes ranging from 0.5 mm to 5.0 mm, and hydrolyzed by porcine pancreatic α-amylase. The optimal cooking time of WSN determined by squeezing between glasses was 6 min. The results showed that the kinetics of solvation of starch and protein molecules were responsible for changes of the physicochemical properties of WSN during cooking. The susceptibility of starch to α-amylase was influenced by the cooking time, particle size and enzyme treatment. The greater value of rapidly digestible starch (RDS) and lower value of slowly digestible starch (SDS) and resistant starch (RS) were reached at the optimal cooking stage ranging between 63.14-71.97%, 2.47-10.74% and 23.94-26.88%, respectively, indicating the susceptibility on hydrolysis by enzyme was important in defining the cooked stage. The study suggested that cooking quality and digestibility were not correlated but the texture greatly controls the digestibility of the noodles. PMID:26718868

  3. Optimal filtering of dynamics in short-time features for music organization

    DEFF Research Database (Denmark)

    Arenas-García, Jerónimo; Larsen, Jan; Hansen, Lars Kai;

    2006-01-01

    There is an increasing interest in customizable methods for organizing music collections. Relevant music characterization can be obtained from short-time features, but it is not obvious how to combine them to get useful information. In this work, a novel method, denoted as the Positive Constrained...... Orthonormalized Partial Least Squares (POPLS), is proposed. Working on the periodograms of MFCCs time series, this supervised method finds optimal filters which pick up the most discriminative temporal information for any music organization task. Two examples are presented in the paper, the first being a simple...... as superior performance when compared to a fixed filter bank approach suggested previously in the MIR literature. We think that the proposed method is a natural step towards a customized MIR application that generalizes well to a wide range of different music organization tasks....

  4. Finite-Time Thermoeconomic Optimization of a Solar-Driven Heat Engine Model

    Directory of Open Access Journals (Sweden)

    Fernando Angulo-Brown

    2011-01-01

    Full Text Available In the present paper, the thermoeconomic optimization of an irreversible solar-driven heat engine model has been carried out by using finite-time/finite-size thermodynamic theory. In our study we take into account losses due to heat transfer across finite time temperature differences, heat leakage between thermal reservoirs and internal irreversibilities in terms of a parameter which comes from the Clausius inequality. In the considered heat engine model, the heat transfer from the hot reservoir to the working fluid is assumed to be Dulong-Petit type and the heat transfer to the cold reservoir is assumed of the Newtonian type. In this work, the optimum performance and two design parameters have been investigated under two objective functions: the power output per unit total cost and the ecological function per unit total cost. The effects of the technical and economical parameters on the thermoeconomic performance have been also discussed under the aforementioned two criteria of performance.

  5. Research on transformation and optimization of large scale 3D modeling for real time rendering

    Science.gov (United States)

    Yan, Hu; Yang, Yongchao; Zhao, Gang; He, Bin; Shen, Guosheng

    2011-12-01

    During the simulation process of real-time three-dimensional scene, the popular modeling software and the real-time rendering platform are not compatible. The common solution is to create three-dimensional scene model by using modeling software and then transform the format supported by rendering platform. This paper takes digital campus scene simulation as an example, analyzes and solves the problems of surface loss; texture distortion and loss; model flicker and so on during the transformation from 3Ds Max to MultiGen Creator. Besides, it proposes the optimization strategy of model which is transformed. The operation results show that this strategy is a good solution to all kinds of problems existing in transformation and it can speed up the rendering speed of the model.

  6. Optimal Estimation of Diffusion Coefficients from Noisy Time-Lapse-Recorded Single-Particle Trajectories

    DEFF Research Database (Denmark)

    Vestergaard, Christian Lyngby

    2012-01-01

    Optimal Estimation of Diusion Coecients from Noisy Time-Lapse- Measurements of Single-Particle Trajectories Single-particle tracking techniques allow quantitative measurements of diusion at the single-molecule level. Recorded time-series are mostly short and contain considerable measurement noise....... The standard method for estimating diusion coecients from single-particle trajectories is based on leastsquares tting to the experimentally measured mean square displacements. This method is highly inecient, since it ignores the high correlations inherent in these. We derive the exact maximum likelihood...... parameter values. We extend the methods to particles diusing on a uctuating substrate, e.g., exible or semi exible polymers such as DNA, and show that uctuations induce an important bias in the estimates of diusion coecients if they are not accounted for. We apply the methods to obtain precise estimates...

  7. Design Optimization of Mixed-Criticality Real-Time Applications on Cost-Constrained Partitioned Architectures

    DEFF Research Database (Denmark)

    Tamas-Selicean, Domitian; Pop, Paul

    2011-01-01

    -criticality tasks can be integrated onto the same architecture only if there is enough spatial and temporal separation among them. We consider that the separation is provided by partitioning, such that applications run in separate partitions, and each partition is allocated several time slots on a processor. Tasks...... of different SILs can share a partition only if they are all elevated to the highest SIL among them. Such elevation leads to increased development costs.We are interested to determine (i) the mapping of tasks to processors, (ii) the assignment of tasks to partitions, (iii) the sequence and size of the time...... slots on each processor and (iv) the schedule tables, such that all the applications are schedulable and the development costs are minimized. We have proposed a Tabu Search-based approach to solve this optimization problem. The proposed algorithm has been evaluated using several synthetic and real...

  8. An Optimal Mitigation Strategy Against the Asteroid Impact Threat with Short Warning Time

    Science.gov (United States)

    Wie, Bong; Barbee, Brent W.

    2015-01-01

    This paper presents the results of a NASA Innovative Advanced Concept (NIAC) Phase 2 study entitled "An Innovative Solution to NASA's Near-Earth Object (NEO) Impact Threat Mitigation Grand Challenge and Flight Validation Mission Architecture Development." This NIAC Phase 2 study was conducted at the Asteroid Deflection Research Center (ADRC) of Iowa State University in 2012-2014. The study objective was to develop an innovative yet practically implementable mitigation strategy for the most probable impact threat of an asteroid or comet with short warning time (less than 5 years). The mitigation strategy described in this paper is intended to optimally reduce the severity and catastrophic damage of the NEO impact event, especially when we don't have sufficient warning times for non-disruptive deflection of a hazardous NEO. This paper provides an executive summary of the NIAC Phase 2 study results.

  9. Development of a mental health action checklist for improving workplace environment as means of job stress prevention.

    Science.gov (United States)

    Yoshikawa, Toru; Kawakami, Norito; Kogi, Kazutaka; Tsutsumi, Akizumi; Shimazu, Miyuki; Nagami, Makiko; Shimazu, Akihito

    2007-07-01

    An action checklist for improving the workplace environment by means of enhancing mental health of workers (Mental Health Action Check List: MHACL) was developed. The use of the checklist for primary prevention was examined. MHACL was developed through three steps: (1) Review of related references and collection of improvement examples for designing a draft MHACL; (2) pilot application of the draft at industrial workplaces and trials at workshops of occupational health staff; and (3) proposing a new MHACL for general use in industry. Workplace improvement actions related to mental health were listed in eight technical areas. From 84 workplaces in Japan, 201 such actions were collected. Typical improvement action phrases were extracted based on these examples, and a draft MHACL containing 40 generally applicable actions were prepared. This draft was applied to selected workplaces for its use as a tool for group discussion. Then, the utility of the checklist was discussed by 105 occupational health staff working in public service offices. The workshop suggested modifications of the draft MHACL including improved check items and usage procedures and the need to use easy-to-understand actions. The final version of the MHACL comprised 30 items in six technical areas: A) sharing work planning, B) work time and organization, C) ergonomic work methods, D) workplace environment, E) mutual support in the workplace, and F) preparedness and care. A new action checklist was proposed for use as a means of changing existing workplace environments and proposing practical actions for improving it. The checklist was confirmed to be useful for organizing workplace-level discussion for identifying immediate improvements at the workplace. The checklist is expected to be widely applied for promoting primary prevention measures in terms of better mental health.

  10. Development of a mental health action checklist for improving workplace environment as means of job stress prevention.

    Science.gov (United States)

    Yoshikawa, Toru; Kawakami, Norito; Kogi, Kazutaka; Tsutsumi, Akizumi; Shimazu, Miyuki; Nagami, Makiko; Shimazu, Akihito

    2007-07-01

    An action checklist for improving the workplace environment by means of enhancing mental health of workers (Mental Health Action Check List: MHACL) was developed. The use of the checklist for primary prevention was examined. MHACL was developed through three steps: (1) Review of related references and collection of improvement examples for designing a draft MHACL; (2) pilot application of the draft at industrial workplaces and trials at workshops of occupational health staff; and (3) proposing a new MHACL for general use in industry. Workplace improvement actions related to mental health were listed in eight technical areas. From 84 workplaces in Japan, 201 such actions were collected. Typical improvement action phrases were extracted based on these examples, and a draft MHACL containing 40 generally applicable actions were prepared. This draft was applied to selected workplaces for its use as a tool for group discussion. Then, the utility of the checklist was discussed by 105 occupational health staff working in public service offices. The workshop suggested modifications of the draft MHACL including improved check items and usage procedures and the need to use easy-to-understand actions. The final version of the MHACL comprised 30 items in six technical areas: A) sharing work planning, B) work time and organization, C) ergonomic work methods, D) workplace environment, E) mutual support in the workplace, and F) preparedness and care. A new action checklist was proposed for use as a means of changing existing workplace environments and proposing practical actions for improving it. The checklist was confirmed to be useful for organizing workplace-level discussion for identifying immediate improvements at the workplace. The checklist is expected to be widely applied for promoting primary prevention measures in terms of better mental health. PMID:17721060

  11. Your P.A.D. Checklist

    Science.gov (United States)

    ... risk factor for cardiovascular disease. HDL CHOLESTEROL Date LDL CHOLESTEROL Optimal : less than 100 mg/dL Near Optimal : ... dL Very High : 190 mg/dL and above LDL CHOLESTEROL Date BLOOD GLUCOSE (fasting) Normal : 99 mg/dL ...

  12. The structure of optimal time- and age-dependent harvesting in the Lotka-McKendrik population model.

    Science.gov (United States)

    Hritonenko, Natali; Yatsenko, Yuri

    2007-07-01

    The paper analyzes optimal harvesting of age-structured populations described by the Lotka-McKendrik model. It is shown that the optimal time- and age-dependent harvesting control involves only one age at natural conditions. This result leads to a new optimization problem with the time-dependent harvesting age as an unknown control. The integral Lotka model is employed to explicitly describe the time-varying age of harvesting. It is proven that in the case of the exponential discounting and infinite horizon the optimal strategy is a stationary solution with a constant harvesting age. A numeric example on optimal forest management illustrates the theoretical findings. Discussion and interpretation of the results are provided.

  13. Real-time optimization for batch process%间歇过程实时优化

    Institute of Scientific and Technical Information of China (English)

    杨国军; 李秀喜; 陈赟; 钱宇

    2011-01-01

    In batch process, with uncertainty stemming from model mismatch and process disturbances, it is not sufficient to determine numerically an optimal solution on the basis of a nominal model and apply it to the process to implement an optimization-based control system. In this paper, a new integrated framework for real-time optimization of batch process with the change of operating condition and parameter uncertainty is presented. It mainly constructs with dynamic modeling, model reduction, dynamic optimization, on-line measurement, model updating and nonlinear control. And at last, the optimization strategy has been applied to a typical scale reversible reaction. The results show the feasibility of the proposed strategy to deal with the change of operating condition and the effect of parameter uncertainty and a significant increase in efficient and quality of the process.%由于生产过程中参数的不确定性和各种扰动作用,间歇生产过程的最优操作条件需要随时作出调整以保证生产的正常进行和满足生产产品质量的要求.针对间歇生产过程的操作条件的变化和不确定性因素的影响提出一种应用于间歇生产过程中的实时优化策略,其主要构成步骤包括动态模型建立、模型降阶、动态优化、在线监测、模型更新和在线调整,并以一个典型可逆酯化反应为研究对象进行方法和理论框架的运用,结果表明本文提出的基于在线测量的实时优化方法能够很好地针对生产过程中的操作条件变化和不确定性因素的影响,提高生产效率和产品质量.

  14. Real-time interactive MR imaging system. Sequence optimization, and basic and clinical evaluations

    International Nuclear Information System (INIS)

    A real-time interactive MR imaging system (real-time MRI) is an MR scanner which has a fast image updating cycle and the ability to freely change slice orientation, just like an ultrasound imaging system. Recently, such a system has been developed and installed on a clinical 1.5-Tesla system. The purpose of this study was to optimize the pulse sequences for clinical use and to evaluate the clinical usefulness and basic functionality of real-time MRI. For T1-weighted imaging, FLASH (fast low angle shot) can be selected, and up to 5 frames per second can be acquired depending on the matrix size. For T2-weighted imaging, true FISP (fast imaging with steady-state precession) can be selected, and up to 4 frames per second can be acquired. Maximum C/N between liver and spleen was obtained at a flip angle of 20 degrees on FLASH. Maximum C/N between cardiac cavity and wall was obtained at a flip angle of 60 degrees on true FISP. Localization of the right and left coronary arteries could be performed within 30 seconds in three volunteers. Although the present real-time MRI system has drawbacks such as low spatial resolution and relatively low contrast resolution, we expect real-time MRI to be one of the most important tools for future clinical MRI. (author)

  15. System-level power optimization for real-time distributed embedded systems

    Science.gov (United States)

    Luo, Jiong

    Power optimization is one of the crucial design considerations for modern electronic systems. In this thesis, we present several system-level power optimization techniques for real-time distributed embedded systems, based on dynamic voltage scaling, dynamic power management, and management of peak power and variance of the power profile. Dynamic voltage scaling has been widely acknowledged as an important and powerful technique to trade off dynamic power consumption and delay. Efficient dynamic voltage scaling requires effective variable-voltage scheduling mechanisms that can adjust voltages and clock frequencies adaptively based on workloads and timing constraints. For this purpose, we propose static variable-voltage scheduling algorithms utilizing criticalpath driven timing analysis for the case when tasks are assumed to have uniform switching activities, as well as energy-gradient driven slack allocation for a more general scenario. The proposed techniques can achieve closeto-optimal power savings with very low computational complexity, without violating any real-time constraints. We also present algorithms for power-efficient joint scheduling of multi-rate periodic task graphs along with soft aperiodic tasks. The power issue is addressed through both dynamic voltage scaling and power management. Periodic task graphs are scheduled statically. Flexibility is introduced into the static schedule to allow the on-line scheduler to make local changes to PE schedules through resource reclaiming and slack stealing, without interfering with the validity of the global schedule. We provide a unified framework in which the response times of aperiodic tasks and power consumption are dynamically optimized simultaneously. Interconnection network fabrics point to a new generation of power-efficient and scalable interconnection architectures for distributed embedded systems. As the system bandwidth continues to increase, interconnection networks become power/energy limited as

  16. Design Optimization of Time- and Cost-Constrained Fault-Tolerant Embedded Systems with Checkpointing and Replication

    DEFF Research Database (Denmark)

    Pop, Paul; Izosimov, Viacheslav; Eles, Petru;

    2009-01-01

    decides the assignment of fault-tolerance policies to processes, the optimal placement of checkpoints and the mapping of processes to processors such that multiple transient faults are tolerated and the timing constraints of the application are satisfied. We present several design optimization approaches...

  17. Using a Checklist in Robotic-Assisted Laparoscopic Radical Prostatectomy Procedures.

    Science.gov (United States)

    Jing, Jiamei; Honey, Michelle L L

    2016-08-01

    Robotic surgical systems are relatively new in New Zealand and have been used mainly for laparoscopic radical prostatectomy. Checklists are successfully used in other industries and health care facilities, so we developed a checklist for use during robotic-assisted laparoscopic radical prostatectomy (RALRP) procedures. After a two-month trial using the checklist, we calculated the completeness of each phase of the checklist as a percentage of the number of completed checklists versus total number of compliant checklists in that phase. Operating room personnel participated in an audiotaped focus group and discussed their perceptions about using the RALRP checklist. We collected, transcribed, and reviewed the focus group discussion and thematically analyzed the responses, which confirmed that the checklist served as a guideline and reminder during the setup. Additionally, staff members associated the checklist with improved OR readiness, minimized workflow interruption, improved efficiency, and positive changes in confidence and teamwork. PMID:27472974

  18. The Herpetofauna of Iran:Checklist of Taxonomy, Distribution and Conservation Status

    Institute of Scientific and Technical Information of China (English)

    Barbod SAFAEI-MAHROO; Reza NASRABADI; Mehdi RAJABIZADEH; Meysam MASHAYEKHI; Alireza MOTESHAREI; Alireza NADERI; Seyed Mahdi KAZEMI; Hanyeh GHAFFARI; Hadi FAHIMI; Siamak BROOMAND; Mahtab YAZDANIAN; Elnaz NAJAFI MAJD; Elham REZAZADEH; Mahboubeh Sadat HOSSEINZADEH

    2015-01-01

    We present an annotated checklist for a total 241 reptiles and 22 amphibians including 5 frogs, 9 toads, 7 newts and salamanders, 1 crocodile, 1 worm lizard, 148 lizards, 79 snakes and 12 turtles and tortoises, includes the most scientific literature up to August 2014 and also based on several field surveys conducted in different Provinces of Iran from 2009 to 2014. We present an up-to-dated checklist of reptiles and amphibians in Iran. We provide a comprehensive listing of taxonomy, names, distribution and conservation status of all amphibians and reptiles of Iran. This checklist includes all recognized named taxa, English names for classes, orders, families, species, subspecies along with Persian names for species, including indication of native and introduced species. For the first time we report two non-native introduced reptiles from natural habitats of Iran. Of the total 22 species of amphibians in Iran, 6 (27.2%) are endemic and of the total 241 species of reptiles, 55 (22.8%) are endemic. Of the 22 amphibians species in Iran, 3 (13%) are Critically Endangered, 2 (9%) are Vulnerable and of the 241 reptile species 3 (1.2%) are Critically Endangered, 4 (1.6%) are Endangered and 10 (4.1%) are Vulnerable. Accordingly, this paper combines significant aspects of taxonomy, common names, conservation status and distribution of the Iranian herpetofauna.

  19. Low temperature, IBA concentrations and optimal time for adventitious rooting of Eucalyptus benthamii mini-cuttings

    Institute of Scientific and Technical Information of China (English)

    Gilvano Ebling Brondani; Francisco José Benedini Baccarin; Heron Wilhelmus de Wit Ondas; José Luiz Stape; Antonio Natal Gon(c)alves; Marcilio de Almeida

    2012-01-01

    Eucalyptus benthamii is a forest species of economic interest that has difficulty with seed production and also is considered to have difficulty with adventitious rooting using propagation techniques,such as cutting or mini-cutting.We aimed to assess the adventitious rooting percentage under different storage times in low temperatures and at various IBA (indole-3-butyric acid) concentrations to determine the optimal time of permanence for rooting Eucalyptus benthamii minicuttings in a greenhouse.Shoots collected from mini-stumps cultivated in a semi-hydroponic system were used to obtain the mini-cuttings.For the first experiment,the mini-cuttings were stored at 4℃ for 0 (immediate planting),24,48,72,96 and 120 h.The second experiment evaluated the rooting dynamic to determine the optimal time of permanence for minicuttings in a greenhouse.The basal region of the mini-cutting was treated with various 1BA solutions:0 (free of IBA),1,000,2,000,3,000 and 4,000 mg·L-1.Every seven days (0 (immediate planting),7,14,21 and 28days),destructive sampling of the mini-cuttings was performed to evaluate the histology of the adventitious rooting.Eucalyptus benthamii minicuttings should be rooted immediately after the collection of the shoots.The 2,000 mg·L-1 IBA concentration induced a greater speed and percentage of adventitious rooting,and an interval of 35 to 42 days was indicated for permanence of the mini-cuttings in the greenhouse.Exposure to low temperature induced adventitious root formation with diffuse vascular connections.

  20. Optimizing functional MR urography: prime time for a 30-minutes-or-less fMRU

    International Nuclear Information System (INIS)

    Current protocols for functional MR urography (fMRU) require long scan times, limiting its widespread use. Our goal was to use pre-defined criteria to reduce the number of sequences and thus the examination time without compromising the morphological and functional results. The standard fMRU protocol in our department consists of eight sequences, including a 17-min dynamic post-contrast scan. Ninety-nine children and young adults (43 male, 56 female, mean age 7 years) were evaluated with this protocol. Each sequence was retrospectively analyzed for its utility and factors that affect its duration. Mean scan time to perform the eight sequences, without including the variable time between sequences, was 40.5 min. Five sequences were categorized as essential: (1) sagittal T2 for planning the oblique coronal plane, (2) axial T2 with fat saturation for the assessment of corticomedullary differentiation and parenchymal thickness, (3) coronal 3-D T2 with fat saturation for multiplanar and 3-D reconstructions, (4) pre-contrast coronal T1 with fat saturation to ensure an appropriate scan prior to injecting the contrast material and (5) the coronal post-contrast dynamic series. Functional information was obtained after 8 min of dynamic imaging in the majority of children. The coronal fat-saturated T2, coronal T1, and post-contrast sagittal fat-saturated T1 sequences did not provide additional information. Because of the effects of pelvicalyceal dilation and ureteropelvic angle on the renal transit time, prone position is recommended, at least in children with high-grade pelvicalyceal dilation. Comprehensive fMRU requires approximately 19 min for sequence acquisition. Allowing for time between sequences and motion correction, the total study time can be reduced to about 30 min. Four pre-contrast sequences and a shortened post-contrast dynamic scan, optimally with the child in prone position, are sufficient. (orig.)

  1. Optimizing functional MR urography: prime time for a 30-minutes-or-less fMRU

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, Jorge; Bedoya, Maria A.; Adeb, Melkamu; Carson, Robert H.; Khrichenko, Dmitry [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); Johnson, Ann M.; Darge, Kassa [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); University of Pennsylvania, Department of Radiology, The Perelman School of Medicine, Philadelphia, PA (United States); Canning, Douglas A. [University of Pennsylvania, Division of Urology, Department of Surgery, The Children' s Hospital of Philadelphia, The Perelman School of Medicine, Philadelphia, PA (United States)

    2015-08-15

    Current protocols for functional MR urography (fMRU) require long scan times, limiting its widespread use. Our goal was to use pre-defined criteria to reduce the number of sequences and thus the examination time without compromising the morphological and functional results. The standard fMRU protocol in our department consists of eight sequences, including a 17-min dynamic post-contrast scan. Ninety-nine children and young adults (43 male, 56 female, mean age 7 years) were evaluated with this protocol. Each sequence was retrospectively analyzed for its utility and factors that affect its duration. Mean scan time to perform the eight sequences, without including the variable time between sequences, was 40.5 min. Five sequences were categorized as essential: (1) sagittal T2 for planning the oblique coronal plane, (2) axial T2 with fat saturation for the assessment of corticomedullary differentiation and parenchymal thickness, (3) coronal 3-D T2 with fat saturation for multiplanar and 3-D reconstructions, (4) pre-contrast coronal T1 with fat saturation to ensure an appropriate scan prior to injecting the contrast material and (5) the coronal post-contrast dynamic series. Functional information was obtained after 8 min of dynamic imaging in the majority of children. The coronal fat-saturated T2, coronal T1, and post-contrast sagittal fat-saturated T1 sequences did not provide additional information. Because of the effects of pelvicalyceal dilation and ureteropelvic angle on the renal transit time, prone position is recommended, at least in children with high-grade pelvicalyceal dilation. Comprehensive fMRU requires approximately 19 min for sequence acquisition. Allowing for time between sequences and motion correction, the total study time can be reduced to about 30 min. Four pre-contrast sequences and a shortened post-contrast dynamic scan, optimally with the child in prone position, are sufficient. (orig.)

  2. Time Resolved Temperature Measurement of Hypervelocity Impact Generated Plasma Using a Global Optimization Method

    Science.gov (United States)

    Hew, Y. M.; Linscott, I.; Close, S.

    2015-12-01

    Meteoroids and orbital debris, collectively referred to as hypervelocity impactors, travel between 7 and 72 km/s in free space. Upon their impact onto the spacecraft, the energy conversion from kinetic to ionization/vaporization occurs within a very brief timescale and results in a small and dense expanding plasma with a very strong optical flash. The radio frequency (RF) emission produced by this plasma can potentially lead to electrical anomalies within the spacecraft. In addition, space weather, such as solar activity and background plasma, can establish spacecraft conditions which can exaggerate the damages done by these impacts. During the impact, a very strong impact flash will be generated. Through the studying of this emission spectrum of the impact, we hope to study the impact generated gas cloud/plasma properties. The impact flash emitted from a ground-based hypervelocity impact test is long expected by many scientists to contain the characteristics of the impact generated plasma, such as plasma temperature and density. This paper presents a method for the time-resolved plasma temperature estimation using three-color visible band photometry data with a global pattern search optimization method. The equilibrium temperature of the plasma can be estimated using an optical model which accounts for both the line emission and continuum emission from the plasma. Using a global pattern search based optimizer, the model can isolate the contribution of the continuum emission versus the line emission from the plasma. The plasma temperature can thus be estimated. Prior to the optimization step, a Gaussian process is also applied to extract the optical emission signal out of the noisy background. The resultant temperature and line-to-continuum emission weighting factor are consistent with the spectrum of the impactor material and current literature.

  3. Optimal routing of hazardous substances in time-varying, stochastic transportation networks

    Energy Technology Data Exchange (ETDEWEB)

    Woods, A.L. [ed.] [Amarillo National Resource Center for Plutonium, TX (United States); Miller-Hooks, E.; Mahmassani, H.S. [Univ. of Texas, Austin, TX (United States). Dept. of Civil Engineering

    1998-07-01

    This report is concerned with the selection of routes in a network along which to transport hazardous substances, taking into consideration several key factors pertaining to the cost of transport and the risk of population exposure in the event of an accident. Furthermore, the fact that travel time and the risk measures are not constant over time is explicitly recognized in the routing decisions. Existing approaches typically assume static conditions, possibly resulting in inefficient route selection and unnecessary risk exposure. The report described the application of recent advances in network analysis methodologies to the problem of routing hazardous substances. Several specific problem formulations are presented, reflecting different degrees of risk aversion on the part of the decision-maker, as well as different possible operational scenarios. All procedures explicitly consider travel times and travel costs (including risk measures) to be stochastic time-varying quantities. The procedures include both exact algorithms, which may require extensive computational effort in some situations, as well as more efficient heuristics that may not guarantee a Pareto-optimal solution. All procedures are systematically illustrated for an example application using the Texas highway network, for both normal and incident condition scenarios. The application illustrates the trade-offs between the information obtained in the solution and computational efficiency, and highlights the benefits of incorporating these procedures in a decision-support system for hazardous substance shipment routing decisions.

  4. Optimal routing of hazardous substances in time-varying, stochastic transportation networks

    International Nuclear Information System (INIS)

    This report is concerned with the selection of routes in a network along which to transport hazardous substances, taking into consideration several key factors pertaining to the cost of transport and the risk of population exposure in the event of an accident. Furthermore, the fact that travel time and the risk measures are not constant over time is explicitly recognized in the routing decisions. Existing approaches typically assume static conditions, possibly resulting in inefficient route selection and unnecessary risk exposure. The report described the application of recent advances in network analysis methodologies to the problem of routing hazardous substances. Several specific problem formulations are presented, reflecting different degrees of risk aversion on the part of the decision-maker, as well as different possible operational scenarios. All procedures explicitly consider travel times and travel costs (including risk measures) to be stochastic time-varying quantities. The procedures include both exact algorithms, which may require extensive computational effort in some situations, as well as more efficient heuristics that may not guarantee a Pareto-optimal solution. All procedures are systematically illustrated for an example application using the Texas highway network, for both normal and incident condition scenarios. The application illustrates the trade-offs between the information obtained in the solution and computational efficiency, and highlights the benefits of incorporating these procedures in a decision-support system for hazardous substance shipment routing decisions

  5. Autonomous Growing Neural Gas for applications with time constraint: optimal parameter estimation.

    Science.gov (United States)

    García-Rodríguez, José; Angelopoulou, Anastassia; García-Chamizo, Juan Manuel; Psarrou, Alexandra; Orts Escolano, Sergio; Morell Giménez, Vicente

    2012-08-01

    This paper aims to address the ability of self-organizing neural network models to manage real-time applications. Specifically, we introduce fAGNG (fast Autonomous Growing Neural Gas), a modified learning algorithm for the incremental model Growing Neural Gas (GNG) network. The Growing Neural Gas network with its attributes of growth, flexibility, rapid adaptation, and excellent quality of representation of the input space makes it a suitable model for real time applications. However, under time constraints GNG fails to produce the optimal topological map for any input data set. In contrast to existing algorithms, the proposed fAGNG algorithm introduces multiple neurons per iteration. The number of neurons inserted and input data generated is controlled autonomous and dynamically based on a priory or online learnt model. A detailed study of the topological preservation and quality of representation depending on the neural network parameter selection has been developed to find the best alternatives to represent different linear and non-linear input spaces under time restrictions or specific quality of representation requirements. PMID:22386599

  6. An optimization algorithm for a capacitated vehicle routing problem with time windows

    Indian Academy of Sciences (India)

    PINAR KIRCI

    2016-05-01

    In this paper, vehicle routing problem (VRP) with time windows and real world constraints are considered as a real-world application on google maps. Also, tabu search is used and Hopfield neural networks is utilized. Basic constraints consist of customer demands, time windows, vehicle speed, vehicle capacity andworking hours. Recently, cost and on-time delivery are the most important actors in logistics. Thus, the logistic applications attract attention of companies. In logistic management, determining the locations of delivery points and deciding the path are the vital components that should be considered. Deciding the paths of vehicles provides companies to use their vehicles efficiently. And with utilizing optimized paths, big amounts of cost and time savings will be gained. The main aim of the work is providing the best path according to the needs of the customers, minimizing the costs with utilizing the VRP and presenting an application for companies that need logistic management. To compare the results, simulated annealing is used on special scenarios. And t-test is performed in the study for the visited path in km with p-value of 0.05.

  7. Applying Particle Swarm Optimization for Solving Team Orienteering Problem with Time Windows

    Directory of Open Access Journals (Sweden)

    The Jin Ai

    2014-01-01

    Full Text Available The Team Orienteering Problem With Time Windows (TOPTW is a transportation problem case that have a set of vertices with a score, service time, and the time windows, start and final at a depot location. A number of paths are constructed to maximize the total collected score by the vertices which is visited. Each vertice can be visited only once and the visit can only start during the  time window of vertices. This paper proposes a Particle Swarm Optimization algorithm for solving the TOPTW, by defining a specific particle for representing the solution of TOPTW within the PSO algorithm and two alternatives, called PSO_TOPTW1 and PSO_TOPTW2, for translating the particle position to form the routes of the path. The performance of the proposed PSO algorithm is evaluated through some benchmark data problem available in the literature. The computational results show that the proposed PSO is able to produce sufficiently good TOPTW solutions that are comparable with corresponding solutions from other existing methods for solving the TOPTW.

  8. Accessibility in Public Buildings: Efficiency of Checklist Protocols.

    Science.gov (United States)

    Andersson, Jonas E; Skehan, Terry

    2016-01-01

    In Sweden, governmental agencies and bodies are required to implement a higher level of accessibility in their buildings than that stipulated by the National Building and Planning Act (PBL). The Swedish Agency for Participation (MFD, Myndigheten för delaktighet) develops holistic guidelines in order to conceptualize this higher level of accessibility. In conjunction to these guidelines, various checklist protocols have been produced. The present study focuses on the efficiency of such checklist protocols. The study revolved around the use of a checklist protocol in assessments of two buildings in Stockholm: the new head office for the National Authority for Social Insurances (ASI) and the School of Architecture at the Royal Institute of Technology (KTH). The study included three groups: Group 1 and Group 2 consisted of 50 real estate managers employed by the ASI, while Group 3 consisted of three participants in a course at the KTH. The results were similar in all of the groups. The use of the checklist protocol generated queries, which related mainly to two factors: (1) the accompanying factsheet consisted of textual explanations with no drawings, photographs or illustrations and (2) the order of the questions in the checklist protocol was difficult to correlate with the two buildings' spatial logic of accessing, egressing and making use of the built space. PMID:27534293

  9. Optimal timing for early surgery in infective endocarditis: a meta-analysis.

    Science.gov (United States)

    Liang, Fuxiang; Song, Bing; Liu, Ruisheng; Yang, Liu; Tang, Hanbo; Li, Yuanming

    2016-03-01

    To systematically review early surgery and the optimal timing of surgery in patients with infective endocarditis (IE), a search for foreign and domestic articles on cohort studies about the association between early surgery and infective endocarditis published from inception to January 2015 was conducted in the PubMed, EMBASE, Chinese Biomedical Literature (CBM), Wanfang and Chinese National Knowledge Infrastructure (CNKI) databases. The studies were screened according to the inclusion and exclusion criteria, the data were extracted and the quality of the method of the included studies was assessed. Then, the meta-analysis was performed using the Stata 12.0 software. Sixteen cohort studies, including 8141 participants were finally included. The results of the meta-analysis revealed that, compared with non-early surgery, early surgery in IE lowers the incidence of in-hospital mortality [odds ratio (OR) = 0.57, 95% confidence interval (CI) (0.42, 0.77); P = 0.000, I(2) = 73.1%] and long-term mortality [OR = 0.57, 95% CI (0.43, 0.77); P = 0.001, I(2) = 67.4%]. Further, performing operation within 2 weeks had a more favourable effect on long-term mortality [OR = 0.63, 95% CI (0.41, 0.97); P = 0.192, I(2) = 39.4%] than non-early surgery. In different kinds of IE, we found that early surgery for native valve endocarditis (NVE) had a lower in-hospital [OR = 0.46, 95% CI (0.31, 0.69); P = 0.001, I(2) = 73.0%] and long-term [OR = 0.57, 95% CI (0.40, 0.81); P = 0.001, I(2) = 68.9%] mortality than the non-early surgery group. However, for prosthetic valve endocarditis (PVE), in-hospital mortality did not differ significantly [OR = 0.83, 95% CI (0.65, 1.06); P = 0.413, I(2) = 0.0%] between early and non-early surgery. We concluded that early surgery was associated with lower in-hospital and long-term mortality compared with non-early surgical treatment for IE, especially in NVE. However, the optimal timing of surgery remains unclear. Additional larger prospective clinical

  10. Optimization aspects of the ARAC real-time radiological emergency response system

    International Nuclear Information System (INIS)

    The Atmospheric Release Advisory Capability (ARAC) project at the Lawrence Livermore National Laboratory responds to radiological emergencies throughout the Continental United States. Using complex three-dimensional dispersion models to account for the effects of complex meteorology and regional terrain, ARAC simulates the release of radioactive materials and provides dispersion, deposition, and dose calculations that are displayed over local geographic features for use by authorities at the accident/release site. ARAC's response is ensured by a software system that (1) makes optimal use of dispersion models, (2) minimizes the time required to provide projections, and (3) maximizes the fault-tolerance of the system. In this paper we describe ARAC's goals and functionality and the costs associated with its development and use. Specifically, we address optimizations in ARAC notifications, meteorological data collection, the determination of site- and problem-specific parameters, the generation of site-specific topography and geography, the running of models, and the distribution of ARAC products. We also discuss the backup features employed to ensure ARAC's ability to respond

  11. Optimal base-stock policy for the inventory system with periodic review, backorders and sequential lead times

    DEFF Research Database (Denmark)

    Johansen, Søren Glud; Thorstenson, Anders

    2008-01-01

    We extend well-known formulae for the optimal base stock of the inventory system with continuous review and constant lead time to the case with periodic review and stochastic, sequential lead times. Our extension uses the notion of the 'extended lead time'. The derived performance measures...

  12. Optimized three-dimensional phase-contrast MR angiography with reduced acquisition time

    International Nuclear Information System (INIS)

    This paper presents modified acquisition schemes for phase-contrast MR angiography that reduce by 33% the measurement time for three-dimensional data sets sensitive to flow in all directions. The new sequence scheme combines one flow-compensated and three flow-encoded acquisitions. Misregistration artifacts due to patient motion are eliminated through interleaved measurement. Taking the complex difference of each flow-encoded data set from the flow-form, the three flow-sensitive data sets are added to obtain the final angiogram. A more complex pulse sequence scheme was also evaluated with the first data set flow encoded in all directions, and the flow phase inverted for a single direction in each of the other three data sets. Optimization was performed on a standard 1.5-T Magnetom imager with 10 normal subjects and selected patients

  13. Real Time Direction of Arrival Estimation in Noisy Environment Using Particle Swarm Optimization with Single Snapshot

    Directory of Open Access Journals (Sweden)

    Fawad Zaman

    2012-07-01

    Full Text Available In this study, we propose a method based on Particle Swarm Optimization for estimating Direction of Arrival of sources impinging on uniform linear array in the presence of noise. Mean Square Error is used as a fitness function which is optimum in nature and avoids any ambiguity among the angles that are supplement to each others. Multiple sources have been taken in the far field of the sensors array. In Case-I the sources are assumed to be far away from each other whereas, in case-II they are assumed to be close enough to each other. The reliability and effectiveness of this proposed algorithm is tested on the bases of comprehensive statistical analysis. The proposed algorithm require single snapshot and can be applied in real time situation.

  14. Background optimization for the neutron time-of-flight spectrometer NEAT

    Science.gov (United States)

    Günther, G.; Russina, M.

    2016-08-01

    The neutron time-of-flight spectrometer NEAT at BER II is currently undergoing a major upgrade where an important aspect is the prevention of parasitic scattering to enhance the signal-to-noise ratio. Here, we discuss the impact of shielding to suppress parasitic scattering from two identified sources of background: the sample environment and detector tubes. By means of Monte Carlo simulations and a modification of the analytical model of Copley et al. [Copley and Cook, 1994], the visibility functions of instrument parts are computed for different shielding configurations. According to three selection criteria, namely suppression of background, transmission and detection limit, the parameters of an oscillating radial collimator are optimized for NEAT's default setup. Moreover, different configurations of detector shielding are discussed to prevent cross-talk within the radial detector system.

  15. Optimality, Rational Expectations and Time Inconsistency Applied to Inflation Targeting Strategy

    Directory of Open Access Journals (Sweden)

    Marius-Corneliu Marinas

    2008-10-01

    Full Text Available The purpose of this paper is to analyse the characteristics of an inflation targeting strategy, using the Barro-Gordon model specific tools. This paper uses the initial Barro-Gordon concepts of inflationary social costs and benefits, adding a new dimension generated by the cost of output deviating from the potential level. The main contribution of this paper is the exhaustive study of the time inconsistency problem generated by the very existence of a policymaker-established inflation rate. The mathematic simulation of a model allowed a complete analysis of several parameters’ influence (parameters such as the optimal rate of inflation, the discount rate, the importance structure of inflationary social cost on the applicable range of the target inflation rate, range that guarantees that the policymakers have no incentive to break their own rules, or at least this incentive is somewhat inferior to the future cost of doing so.

  16. Solving time-dependent problems by an RBF-PS method with an optimal shape parameter

    Energy Technology Data Exchange (ETDEWEB)

    Neves, A M A; Roque, C M C; Ferreira, A J M; Jorge, R M N [Departamento de Engenharia Mecanica e Gestao Industrial, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Soares, C M M, E-mail: ana.m.neves@fe.up.p, E-mail: croque@fe.up.p, E-mail: ferreira@fe.up.p, E-mail: cristovao.mota.soares@dem.ist.utl.p, E-mail: rnatal@fe.up.p [IDMEC - Instituto de Engenharia Mecanica - Instituto Superior Tecnico, Av. Rovisco Pais, 1096 Lisboa Codex (Portugal)

    2009-08-01

    An hybrid technique is used for the solutions of static and time-dependent problems. The idea is to combine the radial basis function (RBF) collocation method and the pseudospectal (PS) method getting to the RBF-PS method. The approach presented in this paper includes a shape parameter optimization and produces highly accurate results. Different examples of the procedure are presented and different radial basis functions are used. One and two-dimensional problems are considered with various boundary and initial conditions. We consider generic problems, but also results on beams and plates. The displacement and the stress analysis are conducted for static and transient dynamic situations. Results obtained are in good agreement with exact solutions or references considered.

  17. Least Squares Ranking on Graphs, Hodge Laplacians, Time Optimality, and Iterative Methods

    CERN Document Server

    Hirani, Anil N; Watts, Seth

    2010-01-01

    Given a set of alternatives to be ranked and some pairwise comparison values, ranking can be posed as a least squares computation on a graph. This was first used by Leake for ranking football teams. The residual can be further analyzed to find inconsistencies in the given data, and this leads to a second least squares problem. This whole process was formulated recently by Jiang et al. as a Hodge decomposition of the edge values. Recently, Koutis et al., showed that linear systems involving symmetric diagonally dominant (SDD) matrices can be solved in time approaching optimality. By using Hodge 0-Laplacian and 2-Laplacian, we give various results on when the normal equations for ranking are SDD and when iterative Krylov methods should be used. We also give iteration bounds for conjugate gradient method for these problems.

  18. Research of an Optimized Mobile IPv6 Real-time Seamless Handover Technology

    Directory of Open Access Journals (Sweden)

    Lei Zhuang

    2011-08-01

    Full Text Available Mobile IPv6 provides mobility support for hosts connecting to the Internet, it solves addressable problems of the mobile terminal, and the mobile terminals can obtain network services without changing IP addresses. But MIPv6 can introduce substantial network expenses and lengthy handoff delay during the mobile handover process, meanwhile, more and more delay sensitive real-time applications require a packet lossless QoS guarantee during a handoff. It proposes an optimized seamless handover mechanism on the basis of existing handoff methods in this paper, it builds on top of the hierarchical method and the fast handoff mechanism and adopts a decision engine-based dynamic distributed architecture, at last it verifies that using this new handoff scheme can reduce packet loss and handoff delay efficiently and improve handoff efficiency by doing simulation experiments.

  19. Note: Ultrasonic gas flowmeter based on optimized time-of-flight algorithms

    Science.gov (United States)

    Wang, X. F.; Tang, Z. A.

    2011-04-01

    A new digital signal processor based single path ultrasonic gas flowmeter is designed, constructed, and experimentally tested. To achieve high accuracy measurements, an optimized ultrasound driven method of incorporation of the amplitude modulation and the phase modulation of the transmit-receive technique is used to stimulate the transmitter. Based on the regularities among the received envelope zero-crossings, different received signal's signal-to-noise ratio situations are discriminated and optional time-of-flight algorithms are applied to take flow rate calculations. Experimental results from the dry calibration indicate that the designed flowmeter prototype can meet the zero-flow verification test requirements of the American Gas Association Report No. 9. Furthermore, the results derived from the flow calibration prove that the proposed flowmeter prototype can measure flow rate accurately in the practical experiments, and the nominal accuracies after FWME adjustment are lower than 0.8% throughout the calibration range.

  20. Note: Ultrasonic gas flowmeter based on optimized time-of-flight algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X. F.; Tang, Z. A. [Department of Electronic Science and Technology, Dalian University of Technology, Dalian, 116023 (China)

    2011-04-15

    A new digital signal processor based single path ultrasonic gas flowmeter is designed, constructed, and experimentally tested. To achieve high accuracy measurements, an optimized ultrasound driven method of incorporation of the amplitude modulation and the phase modulation of the transmit-receive technique is used to stimulate the transmitter. Based on the regularities among the received envelope zero-crossings, different received signal's signal-to-noise ratio situations are discriminated and optional time-of-flight algorithms are applied to take flow rate calculations. Experimental results from the dry calibration indicate that the designed flowmeter prototype can meet the zero-flow verification test requirements of the American Gas Association Report No. 9. Furthermore, the results derived from the flow calibration prove that the proposed flowmeter prototype can measure flow rate accurately in the practical experiments, and the nominal accuracies after FWME adjustment are lower than 0.8% throughout the calibration range.