WorldWideScience

Sample records for time spent traveling

  1. 5 CFR 551.422 - Time spent traveling.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Time spent traveling. 551.422 Section 551... Activities § 551.422 Time spent traveling. (a) Time spent traveling shall be considered hours of work if: (1... who is permitted to use an alternative mode of transportation, or an employee who travels at a time...

  2. Modelling urban travel times

    NARCIS (Netherlands)

    Zheng, F.

    2011-01-01

    Urban travel times are intrinsically uncertain due to a lot of stochastic characteristics of traffic, especially at signalized intersections. A single travel time does not have much meaning and is not informative to drivers or traffic managers. The range of travel times is large such that certain

  3. Value of travel time.

    Science.gov (United States)

    2016-08-01

    Knowingly or not, people generally place economic value on their time. Wage workers are paid a rate per hour, and service providers may charge per hour of their time. In the transportation realm, travelers place a value on their travel time and have ...

  4. Travel time data collection handbook

    Science.gov (United States)

    1998-03-01

    This Travel Time Data Collection Handbook provides guidance to transportation : professionals and practitioners for the collection, reduction, and presentation : of travel time data. The handbook should be a useful reference for designing : travel ti...

  5. Travel time reliability modeling.

    Science.gov (United States)

    2011-07-01

    This report includes three papers as follows: : 1. Guo F., Rakha H., and Park S. (2010), "A Multi-state Travel Time Reliability Model," : Transportation Research Record: Journal of the Transportation Research Board, n 2188, : pp. 46-54. : 2. Park S.,...

  6. Time - A Traveler's Guide

    Science.gov (United States)

    Pickover, Clifford A.

    1999-09-01

    "Bucky Fuller thought big," Wired magazine recently noted, "Arthur C. Clarke thinks big, but Cliff Pickover outdoes them both." In his newest book, Cliff Pickover outdoes even himself, probing a mystery that has baffled mystics, philosophers, and scientists throughout history--What is the nature of time?In Time: A Traveler's Guide , Pickover takes readers to the forefront of science as he illuminates the most mysterious phenomenon in the universe--time itself. Is time travel possible? Is time real? Does it flow in one direction only? Does it have a beginning and an end? What is eternity? Pickover's book offers a stimulating blend of Chopin, philosophy, Einstein, and modern physics, spiced with diverting side-trips to such topics as the history of clocks, the nature of free will, and the reason gold glitters. Numerous diagrams ensure readers will have no trouble following along.By the time we finish this book, we understand a wide variety of scientific concepts pertaining to time. And most important, we will understand that time travel is, indeed, possible.

  7. Travel Time Reliability in Indiana

    OpenAIRE

    Martchouk, Maria; Mannering, Fred L.; Singh, Lakhwinder

    2010-01-01

    Travel time and travel time reliability are important performance measures for assessing traffic condition and extent of congestion on a roadway. This study first uses a floating car technique to assess travel time and travel time reliability on a number of Indiana highways. Then the study goes on to describe the use of Bluetooth technology to collect real travel time data on a freeway and applies it to obtain two weeks of data on Interstate 69 in Indianapolis. An autoregressive model, estima...

  8. Time travel a history

    CERN Document Server

    Gleick, James

    2016-01-01

    From the acclaimed author of The Information and Chaos, here is a mind-bending exploration of time travel: its subversive origins, its evolution in literature and science, and its influence on our understanding of time itself. The story begins at the turn of the previous century, with the young H. G. Wells writing and rewriting the fantastic tale that became his first book and an international sensation: The Time Machine. It was an era when a host of forces was converging to transmute the human understanding of time, some philosophical and some technological: the electric telegraph, the steam railroad, the discovery of buried civilizations, and the perfection of clocks. James Gleick tracks the evolution of time travel as an idea that becomes part of contemporary culture—from Marcel Proust to Doctor Who, from Jorge Luis Borges to Woody Allen. He investigates the inevitable looping paradoxes and examines the porous boundary between pulp fiction and modern physics. Finally, he delves into a temporal shift that...

  9. Approaches to groundwater travel time

    International Nuclear Information System (INIS)

    Kaplan, P.; Klavetter, E.; Peters, R.

    1989-01-01

    One of the objectives of performance assessment for the Yucca Mountain Project is to estimate the groundwater travel time at Yucca Mountain, Nevada, to determine whether the site complies with the criteria specified in the Code of Federal Regulations, Title 10 CFR 60.113 (a). The numerical standard for performance in these criteria is based on the groundwater travel time along the fastest path of likely radionuclide transport from the disturbed zone to the accessible environment. The concept of groundwater travel time as proposed in the regulations, does not have a unique mathematical statement. The purpose of this paper is to discuss the ambiguities associated with the regulatory specification of groundwater travel time, two different interpretations of groundwater travel time, and the effect of the two interpretations on estimates of the groundwater travel time

  10. Approaches to groundwater travel time

    International Nuclear Information System (INIS)

    Kaplan, P.; Klavetter, E.; Peters, R.

    1989-01-01

    One of the objectives of performance assessment for the Yucca Mountain Project is to estimate the groundwater travel time at Yucca Mountain, Nevada, to determine whether the site complies with the criteria specified in the Code of Federal Regulations. The numerical standard for performance in these criteria is based on the groundwater travel time along the fastest path of likely radionuclide transport from the disturbed zone to the accessible environment. The concept of groundwater travel time, as proposed in the regulations, does not have a unique mathematical statement. The purpose of this paper is to discuss (1) the ambiguities associated with the regulatory specification of groundwater travel time, (2) two different interpretations of groundwater travel time, and (3) the effect of the two interpretations on estimates of the groundwater travel time. 3 refs., 2 figs., 2 tabs

  11. Time travel in Goedel's space

    International Nuclear Information System (INIS)

    Pfarr, J.

    1981-01-01

    An analysis is presented of the motion of test particles in Goedel's universe. Both geodesical and nongeodesical motions are considered; the accelerations for nongeodesical motions are given. Examples for closed timelike world lines are shown and the dynamical conditions for time travel in Goedel's space-time are discussed. It is shown that these conditions alone do not suffice to exclude time travel in Goedel's space-time. (author)

  12. Calculation of groundwater travel time

    International Nuclear Information System (INIS)

    Arnett, R.C.; Sagar, B.; Baca, R.G.

    1984-12-01

    Pre-waste-emplacement groundwater travel time is one indicator of the isolation capability of the geologic system surrounding a repository. Two distinct modeling approaches exist for prediction of groundwater flow paths and travel times from the repository location to the designated accessible environment boundary. These two approaches are: (1) the deterministic approach which calculates a single value prediction of groundwater travel time based on average values for input parameters and (2) the stochastic approach which yields a distribution of possible groundwater travel times as a function of the nature and magnitude of uncertainties in the model inputs. The purposes of this report are to (1) document the theoretical (i.e., mathematical) basis used to calculate groundwater pathlines and travel times in a basalt system, (2) outline limitations and ranges of applicability of the deterministic modeling approach, and (3) explain the motivation for the use of the stochastic modeling approach currently being used to predict groundwater pathlines and travel times for the Hanford Site. Example calculations of groundwater travel times are presented to highlight and compare the differences between the deterministic and stochastic modeling approaches. 28 refs

  13. Travel time estimation using Bluetooth.

    Science.gov (United States)

    2015-06-01

    The objective of this study was to investigate the feasibility of using a Bluetooth Probe Detection System (BPDS) to : estimate travel time in an urban area. Specifically, the study investigated the possibility of measuring overall congestion, the : ...

  14. Travel time variability and rational inattention

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Jiang, Gege

    2017-01-01

    This paper sets up a rational inattention model for the choice of departure time for a traveler facing random travel time. The traveler chooses how much information to acquire about the travel time out-come before choosing departure time. This reduces the cost of travel time variability compared...

  15. Ground-water travel time

    International Nuclear Information System (INIS)

    Bentley, H.; Grisak, G.

    1985-01-01

    The Containment and Isolation Working Group considered issues related to the postclosure behavior of repositories in crystalline rock. This working group was further divided into subgroups to consider the progress since the 1978 GAIN Symposium and identify research needs in the individual areas of regional ground-water flow, ground-water travel time, fractional release, and cumulative release. The analysis and findings of the Ground-Water Travel Time Subgroup are presented

  16. Monitoring Travel Time Reliability on Freeways

    NARCIS (Netherlands)

    Tu, Huizhao

    2008-01-01

    Travel time and travel time reliability are important attributes of a trip. The current measures of reliability have in common that in general they all relate to the variability of travel times. However, travel time reliability does not only rely on variability but also on the stability of travel

  17. Experienced travel time prediction for congested freeways

    OpenAIRE

    Yildirimoglu, Mehmet; Geroliminis, Nikolaos

    2013-01-01

    Travel time is an important performance measure for transportation systems, and dissemination of travel time information can help travelers make reliable travel decisions such as route choice or departure time. Since the traffic data collected in real time reflects the past or current conditions on the roadway, a predictive travel time methodology should be used to obtain the information to be disseminated. However, an important part of the literature either uses instantaneous travel time ass...

  18. Valuation of Travel Time and TravelIer Information

    NARCIS (Netherlands)

    Rietveld, Piet

    2003-01-01

    The value of travel time plays an important role in cost benefit analysis of infrastructureprojects. However, the issue of uncertainty on travel times and the implications this has forestimations of travel time values has received much less attention in the literature. In thispaper we compare

  19. Contact Frequency, Travel Time, and Travel Costs for Patients with Rheumatoid Arthritis

    Directory of Open Access Journals (Sweden)

    Jan Sørensen

    2014-01-01

    Full Text Available Objectives. To investigate travel time, and travel cost related to contacts with health care providers for patients with rheumatoid arthritis (RA during a three-month period. Methods. Patient-reported travel time and travel cost were obtained from 2847 patients with RA. Eleven outpatient clinics across Denmark recruited patients to the study. Data collected included frequency, travel time and travel costs for contacts at rheumatology outpatient clinics, other outpatient clinics, general practitioners, privately practicing medical specialists, inpatient hospitals and accident and emergency departments. Results. Over a 3-month period, patients with RA had on average 4.4 (sd 5.7 contacts with health care providers, of which 2.8 (sd 4.0 contacts were with rheumatology outpatient clinics. Private car and public travel were the most frequent modes of travel. The average patient spent 63 minutes and 13 € on travelling per contact, corresponding to a total of 4.6 hours and 56 € during the 3-month period. There was great variation in patient travel time and costs, but no statistically significant associations were found with clinical and sociodemographic characteristics. Conclusion. The results show that patients with RA spend private time and costs on travelling when they seek treatment. These findings are particularly important when analyzing social costs associated with RA.

  20. Contact frequency, travel time, and travel costs for patients with rheumatoid arthritis.

    Science.gov (United States)

    Sørensen, Jan; Linde, Louise; Hetland, Merete Lund

    2014-01-01

    Objectives. To investigate travel time, and travel cost related to contacts with health care providers for patients with rheumatoid arthritis (RA) during a three-month period. Methods. Patient-reported travel time and travel cost were obtained from 2847 patients with RA. Eleven outpatient clinics across Denmark recruited patients to the study. Data collected included frequency, travel time and travel costs for contacts at rheumatology outpatient clinics, other outpatient clinics, general practitioners, privately practicing medical specialists, inpatient hospitals and accident and emergency departments. Results. Over a 3-month period, patients with RA had on average 4.4 (sd 5.7) contacts with health care providers, of which 2.8 (sd 4.0) contacts were with rheumatology outpatient clinics. Private car and public travel were the most frequent modes of travel. The average patient spent 63 minutes and 13 € on travelling per contact, corresponding to a total of 4.6 hours and 56 € during the 3-month period. There was great variation in patient travel time and costs, but no statistically significant associations were found with clinical and sociodemographic characteristics. Conclusion. The results show that patients with RA spend private time and costs on travelling when they seek treatment. These findings are particularly important when analyzing social costs associated with RA.

  1. Forbidden time travel

    DEFF Research Database (Denmark)

    Nøjgaard, Nikolai; Geiß, Manuela; Merkle, Daniel

    2017-01-01

    tree T with a species trees S, relative to the reconciliation problem without prior knowledge of the event types. It is well-known that optimal reconciliations in the unlabeled case may violate time-consistency and thus are not biologically feasible. Here we investigate the mathematical structure...... of the event labeled reconciliation problem with horizontal transfer. Results: We investigate the issue of time-consistency for the event-labeled version of the reconciliation problem, provide a convenient axiomatic framework, and derive a complete characterization of time-consistent reconciliations....... This characterization depends on certain weak conditions on the event-labeled gene trees that reflect conditions under which evolutionary events are observable at least in principle. We give an O(|V (T)| log(|V (S)|))-time algorithm to decide whether a time-consistent reconciliation map exists. It does not require...

  2. Value of travel time savings

    DEFF Research Database (Denmark)

    Le Masurier, P.; Polak, J.; Pawlak, Janet

    2015-01-01

    A team of specialist market researchers and Value of Time experts comprising members from SYSTRA, Imperial College London and the Technical University of Denmark has conducted a formal audit and peer review of research undertaken by Arup/ITS Leeds/Accent to derive Value of Travel Time Savings...... Preference (RP) models that were used to derive final Values of Travel Time (VTT). This report contains the findings of our audit and peer review of the procedures adopted by the research team during data collection of the three surveys (SP, RP and Employers Surveys); a peer review of the reported approach...

  3. Time Travel in the Library

    Science.gov (United States)

    Brown, Donna W.

    2005-01-01

    A Time Travel project in the library gives enthusiasm to students to connect with the past and reinforces their research skills while instilling respect for the past years. The librarian should choose one specific decade to highlight in the library and create an extravaganza that would allow memorabilia from that time period to be located without…

  4. The value of travel time variance

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Engelson, Leonid

    2011-01-01

    This paper considers the value of travel time variability under scheduling preferences that are defined in terms of linearly time varying utility rates associated with being at the origin and at the destination. The main result is a simple expression for the value of travel time variability...... that does not depend on the shape of the travel time distribution. The related measure of travel time variability is the variance of travel time. These conclusions apply equally to travellers who can freely choose departure time and to travellers who use a scheduled service with fixed headway. Depending...... on parameters, travellers may be risk averse or risk seeking and the value of travel time may increase or decrease in the mean travel time....

  5. Fellow travellers: Working memory and mental time travel in rodents.

    Science.gov (United States)

    Dere, Ekrem; Dere, Dorothea; de Souza Silva, Maria Angelica; Huston, Joseph P; Zlomuzica, Armin

    2017-03-19

    The impairment of mental time travel is a severe cognitive symptom in patients with brain lesions and a number of neuropsychiatric disorders. Whether animals are also able to mentally travel in time both forward and backward is still a matter of debate. In this regard, we have proposed a continuum of mental time travel abilities across different animal species, with humans being the species with the ability to perform most sophisticated forms of mental time travel. In this review and perspective article, we delineate a novel approach to understand the evolution, characteristics and function of human and animal mental time travel. Furthermore, we propose a novel approach to measure mental time travel in rodents in a comprehensive manner using a test battery composed of well-validated and easy applicable tests. Copyright © 2017. Published by Elsevier B.V.

  6. Costs of travel time uncertainty and benefits of travel time information: Conceptual model and numerical examples

    NARCIS (Netherlands)

    Ettema, D.F.; Timmermans, H.J.P.

    2006-01-01

    A negative effect of congestion that tends to be overlooked is travel time uncertainty. Travel time uncertainty causes scheduling costs due to early or late arrival. The negative effects of travel time uncertainty can be reduced by providing travellers with travel time information, which improves

  7. The value of travel time variance

    OpenAIRE

    Fosgerau, Mogens; Engelson, Leonid

    2010-01-01

    This paper considers the value of travel time variability under scheduling preferences that are de�fined in terms of linearly time-varying utility rates associated with being at the origin and at the destination. The main result is a simple expression for the value of travel time variability that does not depend on the shape of the travel time distribution. The related measure of travel time variability is the variance of travel time. These conclusions apply equally to travellers who can free...

  8. 5 CFR 630.207 - Travel time.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Travel time. 630.207 Section 630.207... and General Provisions for Annual and Sick Leave § 630.207 Travel time. The travel time granted an employee under section 6303(d) of title 5, United States Code, is inclusive of the time necessarily...

  9. Is average daily travel time expenditure constant? In search of explanations for an increase in average travel time.

    NARCIS (Netherlands)

    van Wee, B.; Rietveld, P.; Meurs, H.

    2006-01-01

    Recent research suggests that the average time spent travelling by the Dutch population has increased over the past decades. However, different data sources show different levels of increase. This paper explores possible causes for this increase. They include a rise in incomes, which has probably

  10. Dynamic travel time estimation using regression trees.

    Science.gov (United States)

    2008-10-01

    This report presents a methodology for travel time estimation by using regression trees. The dissemination of travel time information has become crucial for effective traffic management, especially under congested road conditions. In the absence of c...

  11. Effect of Rainfall on Travel Time and Accuracy of Travel Time prediction with rainfall

    OpenAIRE

    CHUNG, E; EL-FAOUZI, NE; KUWAHARA, M

    2007-01-01

    Travel time is an important parameter to report to travelers. From the user's perspective, accurate predictions and an estimate of their precision are more beneficial than the current travel time since conditions may change significantly before a traveler completes the journey. Past researches have developed travel time prediction models without considering accidents and rain. Normally accident and Rain may cause to increase travel time. Therefore, it may be interesting to consider Rain and a...

  12. Additive measures of travel time variability

    DEFF Research Database (Denmark)

    Engelson, Leonid; Fosgerau, Mogens

    2011-01-01

    This paper derives a measure of travel time variability for travellers equipped with scheduling preferences defined in terms of time-varying utility rates, and who choose departure time optimally. The corresponding value of travel time variability is a constant that depends only on preference...... parameters. The measure is unique in being additive with respect to independent parts of a trip. It has the variance of travel time as a special case. Extension is provided to the case of travellers who use a scheduled service with fixed headway....

  13. Network structure and travel time perception.

    Science.gov (United States)

    Parthasarathi, Pavithra; Levinson, David; Hochmair, Hartwig

    2013-01-01

    The purpose of this research is to test the systematic variation in the perception of travel time among travelers and relate the variation to the underlying street network structure. Travel survey data from the Twin Cities metropolitan area (which includes the cities of Minneapolis and St. Paul) is used for the analysis. Travelers are classified into two groups based on the ratio of perceived and estimated commute travel time. The measures of network structure are estimated using the street network along the identified commute route. T-test comparisons are conducted to identify statistically significant differences in estimated network measures between the two traveler groups. The combined effect of these estimated network measures on travel time is then analyzed using regression models. The results from the t-test and regression analyses confirm the influence of the underlying network structure on the perception of travel time.

  14. Accurate estimation of indoor travel times

    DEFF Research Database (Denmark)

    Prentow, Thor Siiger; Blunck, Henrik; Stisen, Allan

    2014-01-01

    The ability to accurately estimate indoor travel times is crucial for enabling improvements within application areas such as indoor navigation, logistics for mobile workers, and facility management. In this paper, we study the challenges inherent in indoor travel time estimation, and we propose...... the InTraTime method for accurately estimating indoor travel times via mining of historical and real-time indoor position traces. The method learns during operation both travel routes, travel times and their respective likelihood---both for routes traveled as well as for sub-routes thereof. InTraTime...... allows to specify temporal and other query parameters, such as time-of-day, day-of-week or the identity of the traveling individual. As input the method is designed to take generic position traces and is thus interoperable with a variety of indoor positioning systems. The method's advantages include...

  15. Time spent on television in European countries

    NARCIS (Netherlands)

    Vergeer, M.R.M.; Coenders, M.T.A.; Scheepers, P.L.H.; Konig, R.P.; Nelissen, P.W.M.; Huysmans, F.J.M.

    2009-01-01

    This study aims to explain the variation in time spent on watching television in 15 European Union countries, using determinants defined at the individual level, and characteristics defined at the national level, such as the number of channels and nature of the television supply. The results of the

  16. The Archaeology of Time travel – An introduction

    OpenAIRE

    Petersson, Bodil; Holtorf, Cornelius

    2010-01-01

    This article introduces the concept of Time Travel as a new way to approach the past in our age. The article deals with the question: What role does the past play for people in our time? The time travel discussion focusses on the following themes: Time travel between materality and virtuality; Time travel on the market of experiences; Designing time travel; Evaluating time travel.

  17. Travel time variability and airport accessibility

    OpenAIRE

    Koster, P.R.; Kroes, E.P.; Verhoef, E.T.

    2010-01-01

    This discussion paper resulted in a publication in Transportation Research Part B: Methodological (2011). Vol. 45(10), pages 1545-1559. This paper analyses the cost of access travel time variability for air travelers. Reliable access to airports is important since it is likely that the cost of missing a flight is high. First, the determinants of the preferred arrival times at airports are analyzed, including trip purpose, type of airport, flight characteristics, travel experience, type of che...

  18. Valuing travel time variability: Characteristics of the travel time distribution on an urban road

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Fukuda, Daisuke

    2012-01-01

    This paper provides a detailed empirical investigation of the distribution of travel times on an urban road for valuation of travel time variability. Our investigation is premised on the use of a theoretical model with a number of desirable properties. The definition of the value of travel time...... variability depends on certain properties of the distribution of random travel times that require empirical verification. Applying a range of nonparametric statistical techniques to data giving minute-by-minute travel times for a congested urban road over a period of five months, we show that the standardized...... travel time is roughly independent of the time of day as required by the theory. Except for the extreme right tail, a stable distribution seems to fit the data well. The travel time distributions on consecutive links seem to share a common stability parameter such that the travel time distribution...

  19. RP and SP Data-Based Travel Time Reliabiality Analysis

    OpenAIRE

    Lu, Ming

    2013-01-01

    Travel time is considered to be the key criterion when making travel related decisions. As the travel decisions are made in a dynamic environment, the travel time also changes according to the real-time operations of the transport system. More and more evidence proves that travellers are not only interested in the expected travel time but also in travel time reliability. Especially for trips that are made regularly, reliability is valued more than travel time itself. This dissertation focuses...

  20. Travel time variability and airport accessibility

    NARCIS (Netherlands)

    Koster, P.R.; Kroes, E.P.; Verhoef, E.T.

    2011-01-01

    We analyze the cost of access travel time variability for air travelers. Reliable access to airports is important since the cost of missing a flight is likely to be high. First, the determinants of the preferred arrival times at airports are analyzed. Second, the willingness to pay (WTP) for

  1. 5 CFR 551.425 - Time spent receiving medical attention.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Time spent receiving medical attention... Relation to Other Activities § 551.425 Time spent receiving medical attention. (a) Time spent waiting for and receiving medical attention for illness or injury shall be considered hours of work if: (1) The...

  2. Ocean acoustic tomography - Travel time biases

    Science.gov (United States)

    Spiesberger, J. L.

    1985-01-01

    The travel times of acoustic rays traced through a climatological sound-speed profile are compared with travel times computed through the same profile containing an eddy field. The accuracy of linearizing the relations between the travel time difference and the sound-speed deviation at long ranges is assessed using calculations made for two different eddy fields measured in the eastern Atlantic. Significant nonlinearities are found in some cases, and the relationships of the values of these nonlinearities to the range between source and receiver, to the anomaly size associated with the eddies, and to the positions of the eddies are studied. An analytical model of the nonlinearities is discussed.

  3. Inter-temporal variation in the travel time and travel cost parameters of transport models

    OpenAIRE

    Börjesson, Maria

    2012-01-01

    The parameters for travel time and travel cost are central in travel demand forecasting models. Since valuation of infrastructure investments requires prediction of travel demand for future evaluation years, inter-temporal variation of the travel time and travel cost parameters is a key issue in forecasting. Using two identical stated choice experiments conducted among Swedish drivers with an interval of 13 years, 1994 and 2007, this paper estimates the inter-temporal variation in travel time...

  4. Value of freeway travel time information

    OpenAIRE

    Soriguera Martí, Francesc

    2013-01-01

    This paper analyzes the value of highway travel time information systems. This is achieved by using notions of expected utility theory to develop a departure time selection and route choice model. The model assumes that every driver has a level of accepted lateness for his trip and some perceived knowledge of the travel times on the route. Only these two inputs support his decisions. The decision making process does not require the consideration of a complex cost function and does not involve...

  5. Multimodal Network Equilibrium with Stochastic Travel Times

    Directory of Open Access Journals (Sweden)

    M. Meng

    2014-01-01

    Full Text Available The private car, unlike public traffic modes (e.g., subway, trolley running along dedicated track-ways, is invariably subject to various uncertainties resulting in travel time variation. A multimodal network equilibrium model is formulated that explicitly considers stochastic link capacity variability in the road network. The travel time of combined-mode trips is accumulated based on the concept of the mean excess travel time (METT which is a summation of estimated buffer time and tardy time. The problem is characterized by an equivalent VI (variational inequality formulation where the mode choice is expressed in a hierarchical logit structure. Specifically, the supernetwork theory and expansion technique are used herein to represent the multimodal transportation network, which completely represents the combined-mode trips as constituting multiple modes within a trip. The method of successive weighted average is adopted for problem solutions. The model and solution method are further applied to study the trip distribution and METT variations caused by the different levels of the road conditions. Results of numerical examples show that travelers prefer to choose the combined travel mode as road capacity decreases. Travelers with different attitudes towards risk are shown to exhibit significant differences when making travel choice decisions.

  6. Highway travel time estimation with data fusion

    CERN Document Server

    Soriguera Martí, Francesc

    2016-01-01

    This monograph presents a simple, innovative approach for the measurement and short-term prediction of highway travel times based on the fusion of inductive loop detector and toll ticket data. The methodology is generic and not technologically captive, allowing it to be easily generalized for other equivalent types of data. The book shows how Bayesian analysis can be used to obtain fused estimates that are more reliable than the original inputs, overcoming some of the drawbacks of travel-time estimations based on unique data sources. The developed methodology adds value and obtains the maximum (in terms of travel time estimation) from the available data, without recurrent and costly requirements for additional data. The application of the algorithms to empirical testing in the AP-7 toll highway in Barcelona proves that it is possible to develop an accurate real-time, travel-time information system on closed-toll highways with the existing surveillance equipment, suggesting that highway operators might provide...

  7. Principles of valuing business travel time savings

    OpenAIRE

    Fowkes, A.S.

    2001-01-01

    OVERVIEW\\ud \\ud There are two approaches to valuing travel time savings to business people. The first is that which has formed the basis of UK policy for about 30 years, and which is set out in Section 2. This takes the value of travel time savings on employer’s business as equal to the gross wage rate plus an allowance for other costs that the employer saves. These might include such things as desk space, computer, tools, uniform, protective clothing, travel expenses. These were investigated...

  8. Freeway travel-time estimation and forecasting.

    Science.gov (United States)

    2012-09-01

    This project presents a microsimulation-based framework for generating short-term forecasts of travel time on freeway corridors. The microsimulation model that is developed (GTsim), replicates freeway capacity drop and relaxation phenomena critical f...

  9. Establishing monitoring programs for travel time reliability.

    Science.gov (United States)

    2014-01-01

    Within the second Strategic Highway Research Program (SHRP 2), Project L02 focused on creating a suite of methods by which transportation agencies could monitor and evaluate travel time reliability. Creation of the methods also produced an improved u...

  10. Public transport travel time and its variability

    OpenAIRE

    Mazloumi Shomali, Ehsan

    2017-01-01

    Executive Summary Public transport agencies around the world are constantly trying to improve the performance of their service, and to provide passengers with a more reliable service. Two major measures to evaluate the performance of a transit system include travel time and travel time variability. Information on these two measures provides operators with a capacity to identify the problematic locations in a transport system and improve operating plans. Likewise, users can benefit through...

  11. The value of business travel time savings

    OpenAIRE

    Fowkes, A.S.; Marks, P.; Nash, C.A.

    1986-01-01

    The value of time savings for business travellers forms a sizeable part of the benefits from trunk road, rail and air transport improvement schemes. It is therefore important to possess appropiate values to place on business travel time savings for evaluation purposes. The normal approach in practice is to adopt the wage rate of the workers in question plus an increment for overheads and non-wage payments. \\ud \\ud In this paper criticisms of this approach are discssed and the implications of ...

  12. SOCIAL INTEGRATION: TESTING ANTECEDENTS OF TIME SPENT ONLINE

    Directory of Open Access Journals (Sweden)

    Lily Suriani Mohd Arif

    2013-07-01

    Full Text Available The literature on the relationship of social integration and time spent onlineprovides conflicting evidence of the relationship of social integration with timespent online. The study identifies and highlightsthe controversy and attempts toclarify the relationship of social integration withtime spent online bydecomposing the construct social integration into its affective and behavioraldimensions . Thestudy tests antecedents and effects of time spent online in arandom sample of senior level undergraduate students at a public university inMalaysia. The findings indicated that while self-report measures of behavioralsocial integration did not predict time spent online, and, the affective socialintegration had an inverse relationship with time spent online.

  13. 5 CFR 550.1404 - Creditable travel time.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Creditable travel time. 550.1404 Section... ADMINISTRATION (GENERAL) Compensatory Time Off for Travel § 550.1404 Creditable travel time. (a) General. Subject... off for time in a travel status if— (1) The employee is required to travel away from the official duty...

  14. Geostatistical evaluation of travel time uncertainties

    International Nuclear Information System (INIS)

    Devary, J.L.

    1983-08-01

    Data on potentiometric head and hydraulic conductivity, gathered from the Wolfcamp Formation of the Permian System, have exhibited tremendous spatial variability as a result of heterogeneities in the media and the presence of petroleum and natural gas deposits. Geostatistical data analysis and error propagation techniques (kriging and conditional simulation) were applied to determine the effect of potentiometric head uncertainties on radionuclide travel paths and travel times through the Wolfcamp Formation. Blok-average kriging was utilized to remove measurement error from potentiometric head data. The travel time calculations have been enhanced by the use of an inverse technique to determine the relative hydraulic conductivity along travel paths. In this way, the spatial variability of the hydraulic conductivity corresponding to streamline convergence and divergence may be included in the analysis. 22 references, 11 figures, 1 table

  15. Contact Frequency, Travel Time, and Travel Costs for Patients with Rheumatoid Arthritis

    OpenAIRE

    Sørensen, Jan; Linde, Louise; Hetland, Merete Lund

    2014-01-01

    Objectives. To investigate travel time, and travel cost related to contacts with health care providers for patients with rheumatoid arthritis (RA) during a three-month period. Methods. Patient-reported travel time and travel cost were obtained from 2847 patients with RA. Eleven outpatient clinics across Denmark recruited patients to the study. Data collected included frequency, travel time and travel costs for contacts at rheumatology outpatient clinics, other outpatient clinics, general prac...

  16. Regular transport dynamics produce chaotic travel times.

    Science.gov (United States)

    Villalobos, Jorge; Muñoz, Víctor; Rogan, José; Zarama, Roberto; Johnson, Neil F; Toledo, Benjamín; Valdivia, Juan Alejandro

    2014-06-01

    In the hope of making passenger travel times shorter and more reliable, many cities are introducing dedicated bus lanes (e.g., Bogota, London, Miami). Here we show that chaotic travel times are actually a natural consequence of individual bus function, and hence of public transport systems more generally, i.e., chaotic dynamics emerge even when the route is empty and straight, stops and lights are equidistant and regular, and loading times are negligible. More generally, our findings provide a novel example of chaotic dynamics emerging from a single object following Newton's laws of motion in a regularized one-dimensional system.

  17. On the relationship between travel time and travel distance of commuters

    NARCIS (Netherlands)

    Rietveld, P.; Zwart, A.P.; Wee, van G.P.; Hoorn, van der T.

    1999-01-01

    This paper gives a detailed empirical analysis of the relationships between different indicators of costs of commuting trips by car: difference as the crow flies, shortest travel time according to route planner, corresponding travel distance, and reported travel time. Reported travel times are

  18. On the relationship between travel time and travel distance in the Netherlands

    NARCIS (Netherlands)

    Rietveld, P.; Zwart, B.; van Wee, B.; van der Hoorn, A.I.J.M.

    1999-01-01

    This paper gives a detailed empirical analysis of the relationships between different indicators of costs of commuting trips by car: difference as the crow flies, shortest travel time according to route planner, corresponding travel distance, and reported travel time. Reported travel times are

  19. A constant travel time budget? In search for explanations for an increase in average travel time

    NARCIS (Netherlands)

    Rietveld, P.; Wee, van B.

    2002-01-01

    Recent research suggests that during the past decades the average travel time of the Dutch population has probably increased. However, different datasources show different levels of increase. Possible causes of the increase in average travel time are presented here. Increased incomes have

  20. A microlevel analysis of residential context and travel time

    OpenAIRE

    Tim Schwanen; Martin Dijst; Frans M Dieleman

    2002-01-01

    The literature on the association between residential context and travel concentrates on distance traveled and modal choice, as these variables are the most important from an environmental perspective. Travel time has received less attention -- an unfortunate oversight in our view, as people's travel decisions are determined by time rather than by distance. By using data from the 1998 Netherlands National Travel Survey, we have considered travel time associated with trip purpose and transport...

  1. Effectiveness of different approaches to disseminating traveler information on travel time reliability. [supporting datasets

    Science.gov (United States)

    2013-11-30

    Travel time reliability information includes static data about traffic speeds or trip times that capture historic variations from day to day, and it can help individuals understand the level of variation in traffic. Unlike real-time travel time infor...

  2. Empirical Study of Travel Time Estimation and Reliability

    OpenAIRE

    Li, Ruimin; Chai, Huajun; Tang, Jin

    2013-01-01

    This paper explores the travel time distribution of different types of urban roads, the link and path average travel time, and variance estimation methods by analyzing the large-scale travel time dataset detected from automatic number plate readers installed throughout Beijing. The results show that the best-fitting travel time distribution for different road links in 15 min time intervals differs for different traffic congestion levels. The average travel time for all links on all days can b...

  3. Adolescent Depression and Time Spent with Parents and Siblings

    Science.gov (United States)

    Desha, Laura N.; Nicholson, Jan M.; Ziviani, Jenny M.

    2011-01-01

    This study examines adolescent depressive symptoms and the quantity and quality of time spent by adolescents with their parents and siblings. We use measures of the quality of relationships with parents and siblings as proxy indicators for the quality of time spent with these social partners. The study emphasizes the salience of parent…

  4. Travel Time Estimation on Urban Street Segment

    Directory of Open Access Journals (Sweden)

    Jelena Kajalić

    2018-02-01

    Full Text Available Level of service (LOS is used as the main indicator of transport quality on urban roads and it is estimated based on the travel speed. The main objective of this study is to determine which of the existing models for travel speed calculation is most suitable for local conditions. The study uses actual data gathered in travel time survey on urban streets, recorded by applying second by second GPS data. The survey is limited to traffic flow in saturated conditions. The RMSE method (Root Mean Square Error is used for research results comparison with relevant models: Akcelik, HCM (Highway Capacity Manual, Singapore model and modified BPR (the Bureau of Public Roads function (Dowling - Skabardonis. The lowest deviation in local conditions for urban streets with standardized intersection distance (400-500 m is demonstrated by Akcelik model. However, for streets with lower signal density (<1 signal/km the correlation between speed and degree of saturation is best presented by HCM and Singapore model. According to test results, Akcelik model was adopted for travel speed estimation which can be the basis for determining the level of service in urban streets with standardized intersection distance and coordinated signal timing under local conditions.

  5. Time Well Spent? Relating Television Use to Children’s Free-Time Activities

    Science.gov (United States)

    Vandewater, Elizabeth A.; Bickham, David S.; Lee, June H.

    2010-01-01

    OBJECTIVES This study assessed the claim that children’s television use interferes with time spent in more developmentally appropriate activities. METHODS Data came from the first wave of the Child Development Supplement, a nationally representative sample of children aged 0 to 12 in 1997 (N = 1712). Twenty-four-hour time-use diaries from 1 randomly chosen weekday and 1 randomly chosen weekend day were used to assess children’s time spent watching television, time spent with parents, time spent with siblings, time spent reading (or being read to), time spent doing homework, time spent in creative play, and time spent in active play. Ordinary least squares multiple regression was used to assess the relationship between children’s television use and time spent pursuing other activities. RESULTS Results indicated that time spent watching television both with and without parents or siblings was negatively related to time spent with parents or siblings, respectively, in other activities. Television viewing also was negatively related to time spent doing homework for 7- to 12-year-olds and negatively related to creative play, especially among very young children (younger than 5 years). There was no relationship between time spent watching television and time spent reading (or being read to) or to time spent in active play. CONCLUSIONS The results of this study are among the first to provide empirical support for the assumptions made by the American Academy of Pediatrics in their screen time recommendations. Time spent viewing television both with and without parents and siblings present was strongly negatively related to time spent interacting with parents or siblings. Television viewing was associated with decreased homework time and decreased time in creative play. Conversely, there was no support for the widespread belief that television interferes with time spent reading or in active play. PMID:16452327

  6. Bi-criteria travelling salesman subtour problem with time threshold

    Science.gov (United States)

    Kumar Thenepalle, Jayanth; Singamsetty, Purusotham

    2018-03-01

    This paper deals with the bi-criteria travelling salesman subtour problem with time threshold (BTSSP-T), which comes from the family of the travelling salesman problem (TSP) and is NP-hard in the strong sense. The problem arises in several application domains, mainly in routing and scheduling contexts. Here, the model focuses on two criteria: total travel distance and gains attained. The BTSSP-T aims to determine a subtour that starts and ends at the same city and visits a subset of cities at a minimum travel distance with maximum gains, such that the time spent on the tour does not exceed the predefined time threshold. A zero-one integer-programming problem is adopted to formulate this model with all practical constraints, and it includes a finite set of feasible solutions (one for each tour). Two algorithms, namely, the Lexi-Search Algorithm (LSA) and the Tabu Search (TS) algorithm have been developed to solve the BTSSP-T problem. The proposed LSA implicitly enumerates the feasible patterns and provides an efficient solution with backtracking, whereas the TS, which is metaheuristic, will give the better approximate solution. A numerical example is demonstrated in order to understand the search mechanism of the LSA. Numerical experiments are carried out in the MATLAB environment, on the different benchmark instances available in the TSPLIB domain as well as on randomly generated test instances. The experimental results show that the proposed LSA works better than the TS algorithm in terms of solution quality and, computationally, both LSA and TS are competitive.

  7. Implementation and testing of the travel time prediction system (TIPS)

    OpenAIRE

    PANT, Prahlad D; UNIVERSITY OF CINCINNATI

    2001-01-01

    RAPPORT DE RECHERCHE FINAL The Travel Time Prediction System (TIPS) is a portable automated system for predicting and displaying travel time for motorists in advance of and through freeway construction work zones,on a real-time basis

  8. Travel Time to Hospital for Childbirth: Comparing Calculated Versus Reported Travel Times in France.

    Science.gov (United States)

    Pilkington, Hugo; Prunet, Caroline; Blondel, Béatrice; Charreire, Hélène; Combier, Evelyne; Le Vaillant, Marc; Amat-Roze, Jeanne-Marie; Zeitlin, Jennifer

    2018-01-01

    Objectives Timely access to health care is critical in obstetrics. Yet obtaining reliable estimates of travel times to hospital for childbirth poses methodological challenges. We compared two measures of travel time, self-reported and calculated, to assess concordance and to identify determinants of long travel time to hospital for childbirth. Methods Data came from the 2010 French National Perinatal Survey, a national representative sample of births (N = 14 681). We compared both travel time measures by maternal, maternity unit and geographic characteristics in rural, peri-urban and urban areas. Logistic regression models were used to study factors associated with reported and calculated times ≥30 min. Cohen's kappa coefficients were also calculated to estimate the agreement between reported and calculated times according to women's characteristics. Results In urban areas, the proportion of women with travel times ≥30 min was higher when reported rather than calculated times were used (11.0 vs. 3.6%). Longer reported times were associated with non-French nationality [adjusted odds ratio (aOR) 1.3 (95% CI 1.0-1.7)] and inadequate prenatal care [aOR 1.5 (95% CI 1.2-2.0)], but not for calculated times. Concordance between the two measures was higher in peri-urban and rural areas (52.4 vs. 52.3% for rural areas). Delivery in a specialised level 2 or 3 maternity unit was a principal determinant of long reported and measured times in peri-urban and rural areas. Conclusions for Practice The level of agreement between reported and calculated times varies according to geographic context. Poor measurement of travel time in urban areas may mask problems in accessibility.

  9. Contact frequency, travel time, and travel costs for patients with rheumatoid arthritis

    DEFF Research Database (Denmark)

    Sørensen, Jan; Linde, Louise; Hetland, Merete Lund

    2014-01-01

    Objectives. To investigate travel time, and travel cost related to contacts with health care providers for patients with rheumatoid arthritis (RA) during a three-month period. Methods. Patient-reported travel time and travel cost were obtained from 2847 patients with RA. Eleven outpatient clinics...... across Denmark recruited patients to the study. Data collected included frequency, travel time and travel costs for contacts at rheumatology outpatient clinics, other outpatient clinics, general practitioners, privately practicing medical specialists, inpatient hospitals and accident and emergency...... and 13 € on travelling per contact, corresponding to a total of 4.6 hours and 56 € during the 3-month period. There was great variation in patient travel time and costs, but no statistically significant associations were found with clinical and sociodemographic characteristics. Conclusion. The results...

  10. Commuters’ valuation of travel time variability in Barcelona

    OpenAIRE

    Javier Asensio; Anna Matas

    2007-01-01

    The value given by commuters to the variability of travel times is empirically analysed using stated preference data from Barcelona (Spain). Respondents are asked to choose between alternatives that differ in terms of cost, average travel time, variability of travel times and departure time. Different specifications of a scheduling choice model are used to measure the influence of various socioeconomic characteristics. Our results show that travel time variability.

  11. Analysis of travel time reliability on Indiana interstates.

    Science.gov (United States)

    2009-09-15

    Travel-time reliability is a key performance measure in any transportation system. It is a : measure of quality of travel time experienced by transportation system users and reflects the efficiency : of the transportation system to serve citizens, bu...

  12. Incorporating travel time reliability into the Highway Capacity Manual.

    Science.gov (United States)

    2014-01-01

    This final report documents the activities performed during SHRP 2 Reliability Project L08: Incorporating Travel Time Reliability into the Highway Capacity Manual. It serves as a supplement to the proposed chapters for incorporating travel time relia...

  13. Value of Travel Time Reliability: A review of current evidence

    OpenAIRE

    Carlos Carrion; David Levinson

    2010-01-01

    Travel time reliability is a fundamental factor in travel behavior. It represents the temporal uncertainty experienced by users in their movement between any two nodes in a network. The importance of the time reliability depends on the penalties incurred by the users. In road networks, travelers consider the existence of a trip travel time uncertainty in different choice situations (departure time, route, mode, and others). In this paper, a systematic review of the current state of research i...

  14. Macroscopic travel time reliability diagrams for freeway networks

    NARCIS (Netherlands)

    Tu, H.; Li, H.; Van Lint, J.W.C.; Knoop, V.L.; Sun, L.

    2013-01-01

    Travel time reliability is considered to be one of the key indicators of transport system performance. Knowledge of the mechanisms of travel time unreliability enables the derivation of explanatory models with which travel time reliability can be predicted and utilized in traffic management.

  15. Travel Time Reliability for Urban Networks : Modelling and Empirics

    NARCIS (Netherlands)

    Zheng, F.; Liu, Xiaobo; van Zuylen, H.J.; Li, Jie; Lu, Chao

    2017-01-01

    The importance of travel time reliability in traffic management, control, and network design has received a lot of attention in the past decade. In this paper, a network travel time distribution model based on the Johnson curve system is proposed. The model is applied to field travel time data

  16. Urban travel time reliability at different traffic conditions

    NARCIS (Netherlands)

    Zheng, Fangfang; Li, Jie; van Zuylen, H.J.; Liu, Xiaobo; Yang, Hongtai

    2017-01-01

    The decision making of travelers for route choice and departure time choice depends on the expected travel time and its reliability. A common understanding of reliability is that it is related to several statistical properties of the travel time distribution, especially to the standard deviation

  17. Cooling-time determination of spent fuel

    International Nuclear Information System (INIS)

    Hsue, S.T.; Hatcher, C.R.; Kaieda, K.

    1979-01-01

    Two methods to determine the cooling time using data from high-resolution gamma-ray measurements are discussed; one is useful when the irradiation history information is available, the other when the irradiation history is not available. We have applied both methods and found that the cooling time can be determined to within an average of 3% and 4.1%, respectively

  18. 5 CFR 610.123 - Travel on official time.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Travel on official time. 610.123 Section... DUTY Weekly and Daily Scheduling of Work Work Schedules § 610.123 Travel on official time. Insofar as practicable travel during nonduty hours shall not be required of an employee. When it is essential that this...

  19. Predicting travel time variability for cost-benefit analysis

    NARCIS (Netherlands)

    Peer, S.; Koopmans, C.; Verhoef, E.T.

    2010-01-01

    Unreliable travel times cause substantial costs to travelers. Nevertheless, they are not taken into account in many cost-benefit-analyses (CBA), or only in very rough ways. This paper aims at providing simple rules on how variability can be predicted, based on travel time data from Dutch highways.

  20. Establishing monitoring programs for travel time reliability. [supporting datasets

    Science.gov (United States)

    2014-01-01

    The objective of this project was to develop system designs for programs to monitor travel time reliability and to prepare a guidebook that practitioners and others can use to design, build, operate, and maintain such systems. Generally, such travel ...

  1. Do Workplace Flexibility Policies Influence Time Spent in Domestic Labor?

    Science.gov (United States)

    Noonan, Mary C.; Estes, Sarah Beth; Glass, Jennifer L.

    2007-01-01

    Using data from a U.S. midwestern sample of mothers and fathers, the authors examine whether using workplace flexibility policies alters time spent in housework and child care. They hypothesize that an individual's policy use will lead to more time in domestic labor and that his or her spouse's policy use will lead to less time in domestic labor.…

  2. Floating / Travelling Gardens of (Postcolonial Time

    Directory of Open Access Journals (Sweden)

    Carmen Concilio

    2017-11-01

    Full Text Available This essay on travelling gardens of (postcolonial time opens with two iconic images of floating gardens in contemporary postcolonial literature: Will Phantom’s bio-garbage rafter, which saves him in the midst of a cyclone in Carpentaria (2008, by the Aboriginal author Alexis Wright, and Pi’s carnivore island-organism in Life of Pi (2001, which cannot save him from his shipwreck, by Canadian writer Yan Martel. These floating, hybrid gardens of the Anthropocene precede the real travelling gardens of both Michael Ondaatje’s The Cat’s Table (2011 and Amitav Ghosh’s Ibis Trilogy (2008-2015, two authors who both indirectly and directly tell the story of botanical gardens in Asia, and of plant and seed smuggling and transplantation (“displacement” also hinting at their historical and economic colonial implications. For, after all, botanical gardens imply a very specific version of care, Cura (Robert Pogue Harrison 2009, while embodying a precise, imperial scientific and economic project (Brockway 2002; Johnson 2011.

  3. Time Spent in Indirect Nursing Care

    Science.gov (United States)

    1983-09-01

    unable to recognize what needs to be done, or lacking motivation . Likewise, head nurses may spend too much time giving Cdirect care (14.5%). Perhaps more...of the head nurse time might be redirected to teaching, supervising, and motivating other staff members. Although the objective data are reliable, the...S7 9 1 a NO .06 P4 Z& V- N. 4 1 oe a ~~3 00 0I xI %A II I-~~~- Lai - E, zCk u atII C.p UA a 5 P44 d4. Ps4 .- U)2 co Ili L I ao r40 ey . 1a ,o 01 𔃾K

  4. Estimated time spent on preventive services by primary care physicians

    Directory of Open Access Journals (Sweden)

    Gradison Margaret

    2008-12-01

    Full Text Available Abstract Background Delivery of preventive health services in primary care is lacking. One of the main barriers is lack of time. We estimated the amount of time primary care physicians spend on important preventive health services. Methods We analyzed a large dataset of primary care (family and internal medicine visits using the National Ambulatory Medical Care Survey (2001–4; analyses were conducted 2007–8. Multiple linear regression was used to estimate the amount of time spent delivering each preventive service, controlling for demographic covariates. Results Preventive visits were longer than chronic care visits (M = 22.4, SD = 11.8, M = 18.9, SD = 9.2, respectively. New patients required more time from physicians. Services on which physicians spent relatively more time were prostate specific antigen (PSA, cholesterol, Papanicolaou (Pap smear, mammography, exercise counseling, and blood pressure. Physicians spent less time than recommended on two "A" rated ("good evidence" services, tobacco cessation and Pap smear (in preventive visits, and one "B" rated ("at least fair evidence" service, nutrition counseling. Physicians spent substantial time on two services that have an "I" rating ("inconclusive evidence of effectiveness", PSA and exercise counseling. Conclusion Even with limited time, physicians address many of the "A" rated services adequately. However, they may be spending less time than recommended for important services, especially smoking cessation, Pap smear, and nutrition counseling. Future research is needed to understand how physicians decide how to allocate their time to address preventive health.

  5. Photoprotection by sunscreen depends on time spent on application.

    Science.gov (United States)

    Heerfordt, Ida M; Torsnes, Linnea R; Philipsen, Peter A; Wulf, Hans Christian

    2018-03-01

    To be effective, sunscreens must be applied in a sufficient quantity and reapplication is recommended. No previous study has investigated whether time spent on sunscreen application is important for the achieved photoprotection. To determine whether time spent on sunscreen application is related to the amount of sunscreen used during a first and second application. Thirty-one volunteers wearing swimwear applied sunscreen twice in a laboratory environment. Time spent and the amount of sunscreen used during each application was measured. Subjects' body surface area accessible for sunscreen application (BSA) was estimated from their height, weight and swimwear worn. The average applied quantity of sunscreen after each application was calculated. Subjects spent on average 4 minutes and 15 seconds on the first application and approximately 85% of that time on the second application. There was a linear relationship between time spent on application and amount of sunscreen used during both the first and the second application (P applications. After the first application, subjects had applied a mean quantity of sunscreen of 0.71 mg/cm 2 on the BSA, and after the second application, a mean total quantity of 1.27 mg/cm 2 had been applied. We found that participants applied a constant amount of sunscreen per minute during both a first and a second application. Measurement of time spent on application of sunscreen on different body sites may be useful in investigating the distribution of sunscreen in real-life settings. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  6. Reviewing interval cancers: Time well spent?

    International Nuclear Information System (INIS)

    Gower-Thomas, Kate; Fielder, Hilary M.P.; Branston, Lucy; Greening, Sarah; Beer, Helen; Rogers, Cerilan

    2002-01-01

    OBJECTIVES: To categorize interval cancers, and thus identify false-negatives, following prevalent and incident screens in the Welsh breast screening programme. SETTING: Breast Test Wales (BTW) Llandudno, Cardiff and Swansea breast screening units. METHODS: Five hundred and sixty interval breast cancers identified following negative mammographic screening between 1989 and 1997 were reviewed by eight screening radiologists. The blind review was achieved by mixing the screening films of women who subsequently developed an interval cancer with screen negative films of women who did not develop cancer, in a ratio of 4:1. Another radiologist used patients' symptomatic films to record a reference against which the reviewers' reports of the screening films were compared. Interval cancers were categorized as 'true', 'occult', 'false-negative' or 'unclassified' interval cancers or interval cancers with minimal signs, based on the National Health Service breast screening programme (NHSBSP) guidelines. RESULTS: Of the classifiable interval films, 32% were false-negatives, 55% were true intervals and 12% occult. The proportion of false-negatives following incident screens was half that following prevalent screens (P = 0.004). Forty percent of the seed films were recalled by the panel. CONCLUSIONS: Low false-negative interval cancer rates following incident screens (18%) versus prevalent screens (36%) suggest that lower cancer detection rates at incident screens may have resulted from fewer cancers than expected being present, rather than from a failure to detect tumours. The panel method for categorizing interval cancers has significant flaws as the results vary markedly with different protocol and is no more accurate than other, quicker and more timely methods. Gower-Thomas, K. et al. (2002)

  7. Time Spent on the Internet and Adolescent Blood Pressure

    Science.gov (United States)

    Cassidy-Bushrow, Andrea E.; Johnson, Dayna A.; Peters, Rosalind M.; Burmeister, Charlotte; Joseph, Christine L. M.

    2015-01-01

    Internet use is nearly ubiquitous among adolescents. Growing evidence suggests heavy Internet use negatively impacts health, yet the relationship between time spent on the Internet and adolescent blood pressure (BP) is unknown. We examined the association between Internet use and elevated BP in a racially diverse cross-sectional sample of 331…

  8. Accuracy of Travel Time Estimation using Bluetooth Technology

    DEFF Research Database (Denmark)

    Araghi, Bahar Namaki; Skoven Pedersen, Kristian; Tørholm Christensen, Lars

    2012-01-01

    Short-term travel time information plays a critical role in Advanced Traffic Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS). In this context, the need for accurate and reliable travel time information sources is becoming increasingly important. Bluetooth Technology (BT......) has been used as a relatively new cost-effective source of travel time estimation. However, due to low sampling rate of BT compared to other sensor technologies, existence of outliers may significantly affect the accuracy and reliability of the travel time estimates obtained using BT. In this study......, the concept of outliers and corresponding impacts on travel time accuracy are discussed. Four different estimators named Min-BT, Max-BT, Med-BT and Avg-BT with different outlier detection logic are presented in this paper. These methods are used to estimate travel times using a BT derived dataset. In order...

  9. Time Travel: Separating Science Fact from Science Fiction.

    Science.gov (United States)

    Al-Khalili, Jim

    2003-01-01

    Suggests that the subject of time travel is the best topic to introduce ideas behind some of the most beautiful and fundamental theories about the nature of space and time. Explains the distinction between the two directions of time travel and how relativity theory forced the abandonment of Newtonian notions about the nature of time. (Author/KHR)

  10. Quantifying travel time variability in transportation networks.

    Science.gov (United States)

    2010-03-01

    Nonrecurring congestion creates significant delay on freeways in urban areas, lending importance : to the study of facility reliability. In locations where traffic detectors record and archive data, : approximate probability distributions for travel ...

  11. Multiple-Factor Based Sparse Urban Travel Time Prediction

    Directory of Open Access Journals (Sweden)

    Xinyan Zhu

    2018-02-01

    Full Text Available The prediction of travel time is challenging given the sparseness of real-time traffic data and the uncertainty of travel, because it is influenced by multiple factors on the congested urban road networks. In our paper, we propose a three-layer neural network from big probe vehicles data incorporating multi-factors to estimate travel time. The procedure includes the following three steps. First, we aggregate data according to the travel time of a single taxi traveling a target link on working days as traffic flows display similar traffic patterns over a weekly cycle. We then extract feature relationships between target and adjacent links at 30 min interval. About 224,830,178 records are extracted from probe vehicles. Second, we design a three-layer artificial neural network model. The number of neurons in input layer is eight, and the number of neurons in output layer is one. Finally, the trained neural network model is used for link travel time prediction. Different factors are included to examine their influence on the link travel time. Our model is verified using historical data from probe vehicles collected from May to July 2014 in Wuhan, China. The results show that we could obtain the link travel time prediction results using the designed artificial neural network model and detect the influence of different factors on link travel time.

  12. Online Learning Solutions for Freeway Travel Time Prediction

    NARCIS (Netherlands)

    Van Lint, J.W.C.

    2008-01-01

    Providing travel time information to travelers on available route alternatives in traffic networks is widely believed to yield positive effects on individual drive behavior and (route/departure time) choice behavior, as well as on collective traffic operations in terms of, for example, overall time

  13. The cost of travel time variability: three measures with properties

    DEFF Research Database (Denmark)

    Engelson, Leonid; Fosgerau, Mogens

    2016-01-01

    This paper explores the relationships between three types of measures of the cost of travel time variability: measures based on scheduling preferences and implicit departure time choice, Bernoulli type measures based on a univariate function of travel time, and mean-dispersion measures. We...

  14. Variability of Travel Times on New Jersey Highways

    Science.gov (United States)

    2011-06-01

    This report presents the results of a link and path travel time study conducted on selected New Jersey (NJ) highways to produce estimates of the corresponding variability of travel time (VTT) by departure time of the day and days of the week. The tra...

  15. Effectiveness of different approaches to disseminating traveler information on travel time reliability.

    Science.gov (United States)

    2014-01-01

    The second Strategic Highway Research Program (SHRP 2) Reliability program aims to improve trip time reliability by reducing the frequency and effects of events that cause travel times to fluctuate unpredictably. Congestion caused by unreliable, or n...

  16. The Role of Perspective in Mental Time Travel.

    Science.gov (United States)

    Ansuini, Caterina; Cavallo, Andrea; Pia, Lorenzo; Becchio, Cristina

    2016-01-01

    Recent years have seen accumulating evidence for the proposition that people process time by mapping it onto a linear spatial representation and automatically "project" themselves on an imagined mental time line. Here, we ask whether people can adopt the temporal perspective of another person when travelling through time. To elucidate similarities and differences between time travelling from one's own perspective or from the perspective of another person, we asked participants to mentally project themselves or someone else (i.e., a coexperimenter) to different time points. Three basic properties of mental time travel were manipulated: temporal location (i.e., where in time the travel originates: past, present, and future), motion direction (either backwards or forwards), and temporal duration (i.e., the distance to travel: one, three, or five years). We found that time travels originating in the present lasted longer in the self- than in the other-perspective. Moreover, for self-perspective, but not for other-perspective, time was differently scaled depending on where in time the travel originated. In contrast, when considering the direction and the duration of time travelling, no dissimilarities between the self- and the other-perspective emerged. These results suggest that self- and other-projection, despite some differences, share important similarities in structure.

  17. Reevaluation of time spent indoors used for exposure dose assessment

    International Nuclear Information System (INIS)

    Hirose, Katsumi; Fujimoto, Kenzo

    2016-01-01

    A time spent indoors of sixteen hours per day (indoor occupancy factor: 0.67) has been used to assess the radiation dose of residents who spend daily life in the area contaminated due to the nuclear accident in Japan. However, much longer time is considered to be spent indoors for recent modern life. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has been used an indoor occupancy factor of 0.8 since 1977 and a few reports suggested much higher indoor occupancy factors. Therefore it is important to reevaluate the indoor occupancy factor using current available survey data in Japan, such as 'NHK 2010 National Time Use Survey' and 'Survey on Time Use and Leisure Activities' of Statistics Bureau with certain assumption of time spent indoors in each daily activity. The total time spent indoors in a day is calculated to be 20.2 hours and its indoor occupancy factor is 0.84. Much lower indoor occupancy factors were derived from the survey data by Statistics Bureau for 10 to 14 and 15 to 19 years old groups and farmers who spend most of their time outdoors although present estimated indoor occupancy factor of 0.84 is still lower than those found in some of the relevant reports. A rounded indoor occupancy factor of 0.80 might be the appropriate conservative reference value to be used for the dose estimation of people who live in radioactively contaminated areas and for other relevant purposes of exposure assessment, taken into consideration the present results and values reported in United States Environmental Protection Agency (US EPA) and UNSCEAR. (author)

  18. Critical capacity, travel time delays and travel time distribution of rapid mass transit systems

    Science.gov (United States)

    Legara, Erika Fille; Monterola, Christopher; Lee, Kee Khoon; Hung, Gih Guang

    2014-07-01

    We set up a mechanistic agent-based model of a rapid mass transit system. Using empirical data from Singapore's unidentifiable smart fare card, we validate our model by reconstructing actual travel demand and duration of travel statistics. We subsequently use this model to investigate two phenomena that are known to significantly affect the dynamics within the RTS: (1) overloading in trains and (2) overcrowding in the RTS platform. We demonstrate that by varying the loading capacity of trains, a tipping point emerges at which an exponential increase in the duration of travel time delays is observed. We also probe the impact on the rail system dynamics of three types of passenger growth distribution across stations: (i) Dirac delta, (ii) uniform and (iii) geometric, which is reminiscent of the effect of land use on transport. Under the assumption of a fixed loading capacity, we demonstrate the dependence of a given origin-destination (OD) pair on the flow volume of commuters in station platforms.

  19. Intercity Travel Demand Analysis Model

    OpenAIRE

    Ming Lu; Hai Zhu; Xia Luo; Lei Lei

    2014-01-01

    It is well known that intercity travel is an important component of travel demand which belongs to short distance corridor travel. The conventional four-step method is no longer suitable for short distance corridor travel demand analysis for the time spent on urban traffic has a great impact on traveler's main mode choice. To solve this problem, the author studied the existing intercity travel demand analysis model, then improved it based on the study, and finally established a combined model...

  20. Backus-Gilbert inversion of travel time data

    Science.gov (United States)

    Johnson, L. E.

    1972-01-01

    Application of the Backus-Gilbert theory for geophysical inverse problems to the seismic body wave travel-time problem is described. In particular, it is shown how to generate earth models that fit travel-time data to within one standard error and having generated such models how to describe their degree of uniqueness. An example is given to illustrate the process.

  1. Collection and analysis of 2013-2014 travel time data.

    Science.gov (United States)

    2017-07-04

    This report documents the findings of Planning Study 27, Collection and Analysis of 2013-2014 Travel Time Data, which is a continuation of Planning Study 24, Analysis of Historical Travel Time Data. The main scope is to analyze newly acquired link-re...

  2. Use of videoconferencing in Wales to reduce carbon dioxide emissions, travel costs and time.

    Science.gov (United States)

    Lewis, Delyth; Tranter, Glynis; Axford, Alan T

    2009-01-01

    In September 2005 a telemedicine service was started to assist multidisciplinary teams in Wales to improve cancer services. In October 2006 and October 2007 users of videoconferencing equipment at one site completed questionnaires. During October 2006 a total of 18,000 km of car travel were avoided, equivalent to 1696 kg of CO(2) emission. During October 2007 a total of 20,800 km of car travel were avoided, equivalent to 2590 kg of CO(2) emission. We estimate that 48 trees would take a year to absorb that quantity of CO(2). The results of the surveys show that exploiting telemedicine makes better use of staff time, reduces the time spent travelling and assists in reducing climate change by limiting the emissions of CO(2).

  3. Wandering tales: evolutionary origins of mental time travel and language

    Science.gov (United States)

    Corballis, Michael C.

    2013-01-01

    A central component of mind wandering is mental time travel, the calling to mind of remembered past events and of imagined future ones. Mental time travel may also be critical to the evolution of language, which enables us to communicate about the non-present, sharing memories, plans, and ideas. Mental time travel is indexed in humans by hippocampal activity, and studies also suggest that the hippocampus in rats is active when the animals replay or pre play activity in a spatial environment, such as a maze. Mental time travel may have ancient origins, contrary to the view that it is unique to humans. Since mental time travel is also thought to underlie language, these findings suggest that language evolved gradually from pre-existing cognitive capacities, contrary to the view of Chomsky and others that language and symbolic thought emerged abruptly, in a single step, within the past 100,000 years. PMID:23908641

  4. Wandering Tales: Evolutionary origins of mental time travel and language

    Directory of Open Access Journals (Sweden)

    Michael Charles Corballis

    2013-07-01

    Full Text Available A central component of mind wandering is mental time travel, the calling to mind of remembered past events and of imagined future ones. Mental time travel may also be critical to the evolution of language, which enables us to communicate about the nonpresent, sharing memories, plans, and ideas. Mental time travel is indexed in humans by hippocampal activity, and studies also suggest that the hippocampus in rats is active when the animals replay or pre play activity in a spatial environment, such as a maze. Mental time travel may have ancient origins, contrary to the view that it is unique to humans. Since mental time travel is also thought to underlie language, these findings suggest that language evolved gradually from pre-existing cognitive capacities, contrary to the view of Chomsky and others that language and symbolic thought emerged abruptly, in a single step, within the past 100,000 years.

  5. Mode choice endogeneity in value of travel time estimation

    DEFF Research Database (Denmark)

    Mabit, Stefan Lindhard; Fosgerau, Mogens

    The current way to estimate value of travel time is to use a mode-specific sample and hence to estimate mode-specific value of travel times. This approach raises certain questions concerning how to generalise the values to a population. A problem would be if there is an uncontrolled sample...... selection mechanism. This is the case if there is correlation between mode choice and the value of travel time that is not controlled for by explanatory variables. What could confuse the estimated values is the difficulty to separate mode effects from user effect. An example would be the effect of income...... of travel time we use a stated choice dataset. These data include binary choice within mode for car and bus. The first approach is to use a probit model to model mode choice using instruments and then use this in the estimation of the value of travel time. The second approach is based on the use of a very...

  6. [Problematic Internet use, time spent online and personality traits].

    Science.gov (United States)

    Laconi, S; Andréoletti, A; Chauchard, E; Rodgers, R F; Chabrol, H

    2016-06-01

    Internet addiction or problematic Internet use is a recent and increasingly recognized disorder which has been consistently associated with many psychiatric disorders, adding to the documented negative consequences of problematic Internet use. However, very few studies have examined the relationship between problematic Internet use and personality traits and none in a French sample. Moreover, those which have evaluated this relationship have mainly been conducted on small samples. The main goal of our study was to explore the relationship between problematic Internet use, time spent online and personality traits in a French sample, taking into account the presence of depressive symptoms, and gender. A sample of 276 participants aged from 18 to 50 (M=28; SD=8.9) completed a questionnaire assessing problematic Internet use, time spent online, the presence of ten personality traits and depressive symptoms. Our results revealed significant differences between genders. Among men, problematic Internet use was associated with personality clusters A and B while in women no cluster or personality traits were associated. Time spent online was predicted by schizoid personality traits among men and avoidant personality traits among women. Our results indicate that cluster A (schizoid and schizotypal) and cluster B traits (borderline and antisocial) play a more important role in problematic Internet use than cluster C traits among men. Differences between men and women regarding the relationships between personality traits, time online and problematic Internet use may be related to differences in the activities engaged in by men and women online. We observed that communication websites use was more prevalent among women while erotic, gambling and shopping websites use was more prevalent among men suggesting that the characteristics of problematic Internet use may vary according to gender. Few studies have examined the relationship between problematic Internet use, time spent

  7. Valuation of travel time savings for intercity travel: The Madrid-Barcelona corridor

    DEFF Research Database (Denmark)

    Roman, Concepcion; Carlos Martin, Juan; Espino, Raquel

    2014-01-01

    We derive values of travel time savings (VOT) for the Madrid-Barcelona corridor, linking the two largest cities in Spain, based on the estimation of discrete choice models among the main public transport services in the corridor: air transport, high speed rail (HSR) and bus. The new HSR alternative...... (which started to operate in February 2008) competes directly with one of the densest airline domestic markets in the world, and its introduction produced substantial improvements in level of service, achieving reductions in travel time of more than 50% over the conventional train. A specifically...... to provide useful information to quantify users' benefits during the lifespan of a given project. We found, as expected, that HSR and air transport users exhibit substantially higher values for saving travel time than bus travellers. Also as expected, savings of waiting time are more valued than savings...

  8. Travel time data collection for measurement of advanced traveler information systems accuracy

    Science.gov (United States)

    2003-06-01

    The objective of this white paper is to recommend an approach to measuring ATIS travel time accuracy so that ITS planners might have the data they need to make cost effective decisions regarding deployment of surveillance technologies to support ATIS...

  9. Modeling, implementation, and validation of arterial travel time reliability : [summary].

    Science.gov (United States)

    2013-11-01

    Travel time reliability (TTR) has been proposed as : a better measure of a facilitys performance than : a statistical measure like peak hour demand. TTR : is based on more information about average traffic : flows and longer time periods, thus inc...

  10. How travellers’ schedule their trips under uncertain travel times

    DEFF Research Database (Denmark)

    Hjorth, Katrine

    Travel times play an important role when people decide where, when and how much to travel. But travel times are not always predictable from the traveller’s point of view: They may vary from day to day due to demand fluctuations, weather conditions, accidents and other unforeseen events that cause...... road capacity to decrease. We refer to this uncertainty as travel time variability (TTV). TTV is likely to affect how travellers schedule their trips, since it affects their probability of arriving late at their destination. We would like to account for TTV in traffic models and cost-benefit analyses......, but in practice there are limits to the kinds of behaviour that can be accommodated in such applications. For that reason, we are not solely interested in explaining travellers’ behaviour, but also in whether this behaviour can be approximated by behavioural models that are simple enough to be applied in traffic...

  11. [Travel times of patients to ambulatory care physicians in Germany].

    Science.gov (United States)

    Schang, Laura; Kopetsch, Thomas; Sundmacher, Leonie

    2017-12-01

    The time needed by patients to get to a doctor's office represents an important indicator of realised access to care. In Germany, findings on travel times are only available from surveys or for some regions. For the first time, this study examines nationwide and physician group-specific travel times in the ambulatory care sector in Germany and describes demographic, supply-side and spatial determinants of variations. Using a full review of patient consultations in the statutory health insurance system from 2009/2010 for 14 physician groups (approximately 518 million cases), case-related travel times by car between patients' places of residence and physician's practices were estimated at the municipal level. Physicians were reached in less than 30 min in 90.8% of cases for primary care physicians and up to 63% of cases for radiologists. Patients between 18 and under 30 years of age travel longer to get to the doctor than other age groups. The average travel time at the county level systematically differs between urban and rural planning areas. In the case of gynecologists, dermatologists and ophthalmologists, the average journey time decreases with increasing physician density at the county level, but remains approximately constant from a recognisable point of inflection. There is no association between primary care physician density and travel time at the district level. Spatial analyses show physician group-specific patterns of regional concentrations with an increased proportion of cases with very long travel times. Patients' travel times are influenced by supply- and demand-side determinants. Interactions between influential determinants should be analysed in depth to examine the extent to which the time travelled is an expression of regional under- or over-supply rather than an expression of patient preferences.

  12. A Dynamic Travel Time Estimation Model Based on Connected Vehicles

    Directory of Open Access Journals (Sweden)

    Daxin Tian

    2015-01-01

    Full Text Available With advances in connected vehicle technology, dynamic vehicle route guidance models gradually become indispensable equipment for drivers. Traditional route guidance models are designed to direct a vehicle along the shortest path from the origin to the destination without considering the dynamic traffic information. In this paper a dynamic travel time estimation model is presented which can collect and distribute traffic data based on the connected vehicles. To estimate the real-time travel time more accurately, a road link dynamic dividing algorithm is proposed. The efficiency of the model is confirmed by simulations, and the experiment results prove the effectiveness of the travel time estimation method.

  13. A Data Model for Determining Weather's Impact on Travel Time

    DEFF Research Database (Denmark)

    Andersen, Ove; Torp, Kristian

    2016-01-01

    Accurate estimating travel times in road networks is a complex task because travel times depends on factors such as the weather. In this paper, we present a generic model for integrating weather data with GPS data to improve the accuracy of the estimated travel times. First, we present a data model...... for storing and map-matching GPS data, and integrating this data with detailed weather data. The model is generic in the sense that it can be used anywhere GPS data and weather data is available. Next, we analyze the correlation between travel time and the weather classes dry, fog, rain, and snow along...... with winds impact on travel time. Using a data set of 1.6 billion GPS records collected from 10,560 vehicles, over a 5 year period from all of Denmark, we show that snow can increase the travel time up to 27% and strong headwind can increase the travel time with up to 19% (compared to dry calm weather...

  14. Wireless data collection system for real-time arterial travel time estimates.

    Science.gov (United States)

    2011-03-01

    This project pursued several objectives conducive to the implementation and testing of a Bluetooth (BT) based system to collect travel time data, including the deployment of a BT-based travel time data collection system to perform comprehensive testi...

  15. Influence of queue propagation and dissipation on route travel times

    DEFF Research Database (Denmark)

    Raovic, Nevena

    into account (Bliemer, 2008). Yperman (2007) indicates that there is a significant difference in queue-propagation and queue-dissipation between the LTM and DQM. This results in different route travel times, and can further affect route choice. In this paper, different approaches to represent queue propagation...... and dissipation through the CTM, LTM and DQM are studied. A simple network allows to show how these approaches influence route travel time. Furthermore, the possibility of changing the existing DQM is considered in order to more realistically represent queue propagation and dissipation, which would lead to more...... accurate route travel times....

  16. Faster than light motion does not imply time travel

    International Nuclear Information System (INIS)

    Andréka, Hajnal; Madarász, Judit X; Németi, István; Székely, Gergely; Stannett, Mike

    2014-01-01

    Seeing the many examples in the literature of causality violations based on faster than light (FTL) signals one naturally thinks that FTL motion leads inevitably to the possibility of time travel. We show that this logical inference is invalid by demonstrating a model, based on (3+1)-dimensional Minkowski spacetime, in which FTL motion is permitted (in every direction without any limitation on speed) yet which does not admit time travel. Moreover, the Principle of Relativity is true in this model in the sense that all observers are equivalent. In short, FTL motion does not imply time travel after all. (paper)

  17. Incorporating activity-travel time uncertainty and stochastic space-time prisms in multistate supernetworks for activity-travel scheduling

    NARCIS (Netherlands)

    Liao, F.; Rasouli, S.; Timmermans, H.J.P.

    2014-01-01

    Multistate supernetwork approach has been advanced recently to study multimodal, multi-activity travel behavior. The approach allows simultaneously modeling multiple choice facets pertaining to activity-travel scheduling behavior, subject to space-time constraints, in the context of full daily

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

    OpenAIRE

    Fu, Fengjie; Ma, Dongfang; Wang, Dianhai; Qian, Wei

    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...

  19. Quantum mechanics of time travel through post-selected teleportation

    International Nuclear Information System (INIS)

    Lloyd, Seth; Garcia-Patron, Raul; Maccone, Lorenzo; Giovannetti, Vittorio; Shikano, Yutaka

    2011-01-01

    This paper discusses the quantum mechanics of closed-timelike curves (CTCs) and of other potential methods for time travel. We analyze a specific proposal for such quantum time travel, the quantum description of CTCs based on post-selected teleportation (P-CTCs). We compare the theory of P-CTCs to previously proposed quantum theories of time travel: the theory is inequivalent to Deutsch's theory of CTCs, but it is consistent with path-integral approaches (which are the best suited for analyzing quantum-field theory in curved space-time). We derive the dynamical equations that a chronology-respecting system interacting with a CTC will experience. We discuss the possibility of time travel in the absence of general-relativistic closed-timelike curves, and investigate the implications of P-CTCs for enhancing the power of computation.

  20. Assessing the Predictability of Scheduled-Vehicle Travel Times

    DEFF Research Database (Denmark)

    Tiesyte, Dalia; Jensen, Christian Søndergaard

    2009-01-01

    One of the most desired and challenging services in collective transport systems is the real-time prediction of the near-future travel times of scheduled vehicles, especially public buses, thus improving the experience of the transportation users, who may be able to better schedule their travel......, and also enabling system operators to perform real-time monitoring. While travel-time prediction has been researched extensively during the past decade, the accuracies of existing techniques fall short of what is desired, and proposed mathematical prediction models are often not transferable to other...... systems because the properties of the travel-time-related data of vehicles are highly context-dependent, making the models difficult to fit. We propose a framework for evaluating various predictability types of the data independently of the model, and we also compare predictability analysis results...

  1. Estimating spatial travel times using automatic vehicle identification data

    Science.gov (United States)

    2001-01-01

    Prepared ca. 2001. The paper describes an algorithm that was developed for estimating reliable and accurate average roadway link travel times using Automatic Vehicle Identification (AVI) data. The algorithm presented is unique in two aspects. First, ...

  2. Application of travel time information for traffic management.

    Science.gov (United States)

    2012-03-01

    This report summarizes findings and implementations of probe vehicle data collection based on Bluetooth MAC address matching : technology. Probe vehicle travel time data are studied in the following field deployment case studies: analysis of traffic ...

  3. Measurement and evaluation of transit travel time reliability

    Science.gov (United States)

    2011-01-01

    Transportation system customers need consistency in their daily travel times to enable them to plan their daily : activities, whether that is a commuter on their way to work, a company setting up delivery schedules for justintime : manufacturin...

  4. Bluetooth-based travel time/speed measuring systems development.

    Science.gov (United States)

    2010-06-01

    Agencies in the Houston region have traditionally used toll tag readers to provide travel times on : freeways and High Occupancy Vehicle (HOV) lanes, but these systems require large amounts of costly and : physically invasive infrastructure. Bluetoot...

  5. Impact of data source on travel time reliability assessment.

    Science.gov (United States)

    2014-08-01

    Travel time reliability measures are becoming an increasingly important input to the mobility and : congestion management studies. In the case of Maryland State Highway Administration, reliability : measures are key elements in the agencys Annual ...

  6. Modeling, implementation, and validation of arterial travel time reliability.

    Science.gov (United States)

    2013-11-01

    Previous research funded by Florida Department of Transportation (FDOT) developed a method for estimating : travel time reliability for arterials. This method was not initially implemented or validated using field data. This : project evaluated and r...

  7. Innovative methods for calculation of freeway travel time using limited data : executive summary report.

    Science.gov (United States)

    2008-08-01

    ODOTs policy for Dynamic Message Sign : utilization requires travel time(s) to be displayed as : a default message. The current method of : calculating travel time involves a workstation : operator estimating the travel time based upon : observati...

  8. Bayesian Nonparametric Model for Estimating Multistate Travel Time Distribution

    Directory of Open Access Journals (Sweden)

    Emmanuel Kidando

    2017-01-01

    Full Text Available Multistate models, that is, models with more than two distributions, are preferred over single-state probability models in modeling the distribution of travel time. Literature review indicated that the finite multistate modeling of travel time using lognormal distribution is superior to other probability functions. In this study, we extend the finite multistate lognormal model of estimating the travel time distribution to unbounded lognormal distribution. In particular, a nonparametric Dirichlet Process Mixture Model (DPMM with stick-breaking process representation was used. The strength of the DPMM is that it can choose the number of components dynamically as part of the algorithm during parameter estimation. To reduce computational complexity, the modeling process was limited to a maximum of six components. Then, the Markov Chain Monte Carlo (MCMC sampling technique was employed to estimate the parameters’ posterior distribution. Speed data from nine links of a freeway corridor, aggregated on a 5-minute basis, were used to calculate the corridor travel time. The results demonstrated that this model offers significant flexibility in modeling to account for complex mixture distributions of the travel time without specifying the number of components. The DPMM modeling further revealed that freeway travel time is characterized by multistate or single-state models depending on the inclusion of onset and offset of congestion periods.

  9. Back or to the future? Preferences of time travelers

    Directory of Open Access Journals (Sweden)

    Ralph Hertwig

    2012-07-01

    Full Text Available Popular culture reflects whatever piques our imagination. Think of the myriad movies and books that take viewers and readers on an imaginary journey to the past or the future (e.g., Gladiator, The Time Machine. Despite the ubiquity of time travel as a theme in cultural expression, the factors that underlie people's preferences concerning the direction of time travel have gone unexplored. What determines whether a person would prefer to visit the (certain past or explore the (uncertain future? We identified three factors that markedly affect people's preference for (hypothetical travel to the past or the future, respectively. Those who think of themselves as courageous, those with a more conservative worldview, and---perhaps counterintuitively---those who are advanced in age prefer to travel into the future. We discuss implications of these initial results.

  10. Human mobility and time spent at destination: impact on spatial epidemic spreading.

    Science.gov (United States)

    Poletto, Chiara; Tizzoni, Michele; Colizza, Vittoria

    2013-12-07

    Host mobility plays a fundamental role in the spatial spread of infectious diseases. Previous theoretical works based on the integration of network theory into the metapopulation framework have shown that the heterogeneities that characterize real mobility networks favor the propagation of epidemics. Nevertheless, the studies conducted so far assumed the mobility process to be either Markovian (in which the memory of the origin of each traveler is lost) or non-Markovian with a fixed traveling time scale (in which individuals travel to a destination and come back at a constant rate). Available statistics however show that the time spent by travelers at destination is characterized by wide fluctuations, ranging from a single day up to several months. Such varying length of stay crucially affects the chance and duration of mixing events among hosts and may therefore have a strong impact on the spread of an emerging disease. Here, we present an analytical and a computational study of epidemic processes on a complex subpopulation network where travelers have memory of their origin and spend a heterogeneously distributed time interval at their destination. Through analytical calculations and numerical simulations we show that the heterogeneity of the length of stay alters the expression of the threshold between local outbreak and global invasion, and, moreover, it changes the epidemic behavior of the system in case of a global outbreak. Additionally, our theoretical framework allows us to study the effect of changes in the traveling behavior in response to the infection, by considering a scenario in which sick individuals do not leave their home location. Finally, we compare the results of our non-Markovian framework with those obtained with a classic Markovian approach and find relevant differences between the two, in the estimate of the epidemic invasion potential, as well as of the timing and the pattern of its spatial spread. These results highlight the importance of

  11. Validation and augmentation of Inrix arterial travel time data using independent sources : [research summary].

    Science.gov (United States)

    2015-02-01

    Although the freeway travel time data has been validated extensively in recent : years, the quality of arterial travel time data is not well known. This project : presents a comprehensive validation scheme for arterial travel time data based : on GPS...

  12. The IPERMOB System for Effective Real-Time Road Travel Time Measurement and Prediction

    OpenAIRE

    Martelli, Francesca; Renda, Maria Elena; Santi, Paolo

    2010-01-01

    Accurate, real-time measurement and estimation of road travel time is considered a central problem in the design of advanced Intelligent Transportation Systems. In particular, whether eective, real-time collection of travel time measurements in a urban area is possible is, to the best of our knowledge, still an open problem. In this paper, we introduce the IPERMOB system for efficient, real-time collection of travel time measurements in urban areas through vehicular networks. We demonstrate t...

  13. Modeling highway travel time distribution with conditional probability models

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira Neto, Francisco Moraes [ORNL; Chin, Shih-Miao [ORNL; Hwang, Ho-Ling [ORNL; Han, Lee [University of Tennessee, Knoxville (UTK)

    2014-01-01

    ABSTRACT Under the sponsorship of the Federal Highway Administration's Office of Freight Management and Operations, the American Transportation Research Institute (ATRI) has developed performance measures through the Freight Performance Measures (FPM) initiative. Under this program, travel speed information is derived from data collected using wireless based global positioning systems. These telemetric data systems are subscribed and used by trucking industry as an operations management tool. More than one telemetric operator submits their data dumps to ATRI on a regular basis. Each data transmission contains truck location, its travel time, and a clock time/date stamp. Data from the FPM program provides a unique opportunity for studying the upstream-downstream speed distributions at different locations, as well as different time of the day and day of the week. This research is focused on the stochastic nature of successive link travel speed data on the continental United States Interstates network. Specifically, a method to estimate route probability distributions of travel time is proposed. This method uses the concepts of convolution of probability distributions and bivariate, link-to-link, conditional probability to estimate the expected distributions for the route travel time. Major contribution of this study is the consideration of speed correlation between upstream and downstream contiguous Interstate segments through conditional probability. The established conditional probability distributions, between successive segments, can be used to provide travel time reliability measures. This study also suggests an adaptive method for calculating and updating route travel time distribution as new data or information is added. This methodology can be useful to estimate performance measures as required by the recent Moving Ahead for Progress in the 21st Century Act (MAP 21).

  14. Time Spent on the Internet and Adolescent Blood Pressure.

    Science.gov (United States)

    Cassidy-Bushrow, Andrea E; Johnson, Dayna A; Peters, Rosalind M; Burmeister, Charlotte; Joseph, Christine L M

    2015-10-01

    Internet use is nearly ubiquitous among adolescents. Growing evidence suggests heavy Internet use negatively impacts health, yet the relationship between time spent on the Internet and adolescent blood pressure (BP) is unknown. We examined the association between Internet use and elevated BP in a racially diverse cross-sectional sample of 331 healthy adolescents (ages 14-17 years). Heavy Internet use was defined as ≥ 2 hr/day, moderate use as Internet users had statistically significantly higher odds of elevated BP compared to light Internet users. School nurses can play an important role in preventing high BP through assessment of BP and other health behaviors including Internet use, and health teaching to individuals, student groups, faculty, and parents to increase awareness of the relationship between Internet use and health. © The Author(s) 2014.

  15. The meandering mind: vection and mental time travel.

    Directory of Open Access Journals (Sweden)

    Lynden K Miles

    Full Text Available BACKGROUND: The ability to travel mentally through time sets humans apart from many other species, yet little is known about this core cognitive capacity. In particular, what shapes the passage of the mind's journey through time? Guided by the viewpoint that higher cognitive activity can have a sensory-motor grounding, we explored the possibility that mental time travel is influenced by apparent movement through space. METHODOLOGY/PRINCIPAL FINDINGS: Participants performed a mundane vigilance task, during which they were expected to daydream, while viewing a display that elicited an illusion of self-motion (i.e., vection. Afterwards, the contents of their mind wandering experiences were probed. The results revealed that the direction of apparent motion influenced the temporal focus of mental time travel. While backward vection prompted thinking about the past, forward vection triggered a preponderance of future-oriented thoughts. CONCLUSIONS/SIGNIFICANCE: Consistent with recent evidence that traveling mentally through time entails associated movements in space, the current results demonstrate the converse relationship-apparent movement through space influenced the temporal locus of mental activity. Together, these findings corroborate the viewpoint that mental time travel may be grounded in the embodiment of spatiotemporal information in a bidirectional manner.

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

    Directory of Open Access Journals (Sweden)

    Fengjie Fu

    2015-01-01

    Full Text Available 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 time estimation value, and the Modified Buffer Time Index (MBIT was expressed as travel time variability; based on the characteristics of travel time change and MBIT along with different time windows, the time window was optimized dynamically for minimum MBIT, requiring that the travel time change be lower than the threshold value and traffic incidents can be detected real time; finally, travel times on Shandong Road in Qingdao were estimated every 10 s, 120 s, optimal time windows, and 480 s and the comparisons demonstrated that travel time estimation in optimal time windows can exactly and steadily reflect the real-time traffic. It verifies the effectiveness of the optimization method.

  17. Reliability of Bluetooth Technology for Travel Time Estimation

    DEFF Research Database (Denmark)

    Araghi, Bahar Namaki; Olesen, Jonas Hammershøj; Krishnan, Rajesh

    2015-01-01

    . However, their corresponding impacts on accuracy and reliability of estimated travel time have not been evaluated. In this study, a controlled field experiment is conducted to collect both Bluetooth and GPS data for 1000 trips to be used as the basis for evaluation. Data obtained by GPS logger is used...... to calculate actual travel time, referred to as ground truth, and to geo-code the Bluetooth detection events. In this setting, reliability is defined as the percentage of devices captured per trip during the experiment. It is found that, on average, Bluetooth-enabled devices will be detected 80% of the time......-range antennae detect Bluetooth-enabled devices in a closer location to the sensor, thus providing a more accurate travel time estimate. However, the smaller the size of the detection zone, the lower the penetration rate, which could itself influence the accuracy of estimates. Therefore, there has to be a trade...

  18. 41 CFR 301-52.14 - What must I do with any travel advance outstanding at the time I submit my travel claim?

    Science.gov (United States)

    2010-07-01

    ... travel advance outstanding at the time I submit my travel claim? 301-52.14 Section 301-52.14 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES... § 301-52.14 What must I do with any travel advance outstanding at the time I submit my travel claim? You...

  19. Issues in the valuation of travel time savings

    DEFF Research Database (Denmark)

    Gissel, Stine

    1998-01-01

    The subject of the paper is the valuation of travel time savings (emanating from investment in transport infrastructure). In the first part of the paper the question is approached within a microeconomic framework. It is discussed if and how the theory can give indications on the relative value...... of travel time elements and on the extrapolation of time values into the future. In the second part of the paper the same questions are investigated on the basis of the results of several empirical studies....

  20. Splitting Travel Time Based on AFC Data: Estimating Walking, Waiting, Transfer, and In-Vehicle Travel Times in Metro System

    Directory of Open Access Journals (Sweden)

    Yong-Sheng Zhang

    2015-01-01

    Full Text Available The walking, waiting, transfer, and delayed in-vehicle travel times mainly contribute to route’s travel time reliability in the metro system. The automatic fare collection (AFC system provides huge amounts of smart card records which can be used to estimate all these times distributions. A new estimation model based on Bayesian inference formulation is proposed in this paper by integrating the probability measurement of the OD pair with only one effective route, in which all kinds of times follow the truncated normal distributions. Then, Markov Chain Monte Carlo method is designed to estimate all parameters endogenously. Finally, based on AFC data in Guangzhou Metro, the estimations show that all parameters can be estimated endogenously and identifiably. Meanwhile, the truncated property of the travel time is significant and the threshold tested by the surveyed data is reliable. Furthermore, the superiority of the proposed model over the existing model in estimation and forecasting accuracy is also demonstrated.

  1. Freeway travel-time estimation and forecasting.

    Science.gov (United States)

    2013-03-01

    Real-time traffic information provided by GDOT has proven invaluable for commuters in the : Georgia freeway network. The increasing number of Variable Message Signs, addition of : services such as My-NaviGAtor, NaviGAtor-to-go etc. and the advancemen...

  2. Extremal inversion of lunar travel time data. [seismic velocity structure

    Science.gov (United States)

    Burkhard, N.; Jackson, D. D.

    1975-01-01

    The tau method, developed by Bessonova et al. (1974), of inversion of travel times is applied to lunar P-wave travel time data to find limits on the velocity structure of the moon. Tau is the singular solution to the Clairaut equation. Models with low-velocity zones, with low-velocity zones at differing depths, and without low-velocity zones, were found to be consistent with data and within the determined limits. Models with and without a discontinuity at about 25-km depth have been found which agree with all travel time data to within two standard deviations. In other words, the existence of the discontinuity and its size and location have not been uniquely resolved. Models with low-velocity channels are also possible.

  3. Similarity-Based Prediction of Travel Times for Vehicles Traveling on Known Routes

    DEFF Research Database (Denmark)

    Tiesyte, Dalia; Jensen, Christian Søndergaard

    2008-01-01

    , historical data in combination with real-time data may be used to predict the future travel times of vehicles more accurately, thus improving the experience of the users who rely on such information. We propose a Nearest-Neighbor Trajectory (NNT) technique that identifies the historical trajectory......The use of centralized, real-time position tracking is proliferating in the areas of logistics and public transportation. Real-time positions can be used to provide up-to-date information to a variety of users, and they can also be accumulated for uses in subsequent data analyses. In particular...... of vehicles that travel along known routes. In empirical studies with real data from buses, we evaluate how well the proposed distance functions are capable of predicting future vehicle movements. Second, we propose a main-memory index structure that enables incremental similarity search and that is capable...

  4. Valuation of travel time for international long-distance travel - results from the Fehmarn Belt stated choice experiment

    DEFF Research Database (Denmark)

    Mabit, Stefan Lindhard; Rich, Jeppe; Burge, Peter

    2013-01-01

    of travel time savings (VTTS). The final model, which was formulated as a nested logit model and included Box–Cox transformed travel time and cost attributes, revealed several interesting findings. Firstly, we found damping effects in both cost and time – most strongly in cost. Secondly, we found...... significant interactions among travel cost and time, and journey characteristics, such as distance and duration. This had direct impact on the VTTS, which was shown to decrease with distance and duration. Thirdly, we found that air travel implies a higher average VTTS, which is to be expected but rarely......The geographical scope of travel varies from short distances in urban areas to long distances across cities and countries. While urban travel has been widely analysed in the literature, travel over longer distances and particularly across countries, has received much less attention. While this may...

  5. Visualizations of Travel Time Performance Based on Vehicle Reidentification Data

    Energy Technology Data Exchange (ETDEWEB)

    Young, Stanley Ernest [National Renewable Energy Lab, 15013 Denver West Parkway, Golden, CO 80401; Sharifi, Elham [Center for Advanced Transportation Technology, University of Maryland, College Park, Technology Ventures Building, Suite 2200, 5000 College Avenue, College Park, MD 20742; Day, Christopher M. [Joint Transportation Research Program, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47906; Bullock, Darcy M. [Lyles School of Civil Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47906

    2017-01-01

    This paper provides a visual reference of the breadth of arterial performance phenomena based on travel time measures obtained from reidentification technology that has proliferated in the past 5 years. These graphical performance measures are revealed through overlay charts and statistical distribution as revealed through cumulative frequency diagrams (CFDs). With overlays of vehicle travel times from multiple days, dominant traffic patterns over a 24-h period are reinforced and reveal the traffic behavior induced primarily by the operation of traffic control at signalized intersections. A cumulative distribution function in the statistical literature provides a method for comparing traffic patterns from various time frames or locations in a compact visual format that provides intuitive feedback on arterial performance. The CFD may be accumulated hourly, by peak periods, or by time periods specific to signal timing plans that are in effect. Combined, overlay charts and CFDs provide visual tools with which to assess the quality and consistency of traffic movement for various periods throughout the day efficiently, without sacrificing detail, which is a typical byproduct of numeric-based performance measures. These methods are particularly effective for comparing before-and-after median travel times, as well as changes in interquartile range, to assess travel time reliability.

  6. Optimization of time and location dependent spent nuclear fuel storage capacity

    International Nuclear Information System (INIS)

    Macek, V.

    1977-01-01

    A linear spent fuel storage model is developed to identify cost-effective spent nuclear fuel storage strategies. The purpose of this model is to provide guidelines for the implementation of the optimal time-dependent spent fuel storage capacity expansion in view of the current economic and regulatory environment which has resulted in phase-out of the closed nuclear fuel cycle. Management alternatives of the spent fuel storage backlog, which is created by mismatch between spent fuel generation rate and spent fuel disposition capability, are represented by aggregate decision variables which describe the time dependent on-reactor-site and off-site spent fuel storage capacity additions, and the amount of spent fuel transferred to off-site storage facilities. Principal constraints of the model assure determination of cost optimal spent fuel storage expansion strategies, while spent fuel storage requirements are met at all times. A detailed physical and economic analysis of the essential components of the spent fuel storage problem, which precedes the model development, assures its realism. The effects of technological limitations on the on-site spent fuel storage expansion and timing of reinitiation of the spent fuel reprocessing on optimal spent fuel storage capacity expansion are investigated. The principal results of the study indicate that (a) expansion of storage capacity beyond that of currently planned facilities is necessary, and (b) economics of the post-reactor fuel cycle is extremely sensitive to the timing of reinitiation of spent fuel reprocessing. Postponement of reprocessing beyond mid-1982 may result in net negative economic liability of the back end of the nuclear fuel cycle

  7. Breast cancer stage at diagnosis: is travel time important?

    Science.gov (United States)

    Henry, Kevin A; Boscoe, Francis P; Johnson, Christopher J; Goldberg, Daniel W; Sherman, Recinda; Cockburn, Myles

    2011-12-01

    Recent studies have produced inconsistent results in their examination of the potential association between proximity to healthcare or mammography facilities and breast cancer stage at diagnosis. Using a multistate dataset, we re-examine this issue by investigating whether travel time to a patient's diagnosing facility or nearest mammography facility impacts breast cancer stage at diagnosis. We studied 161,619 women 40 years and older diagnosed with invasive breast cancer from ten state population based cancer registries in the United States. For each woman, we calculated travel time to their diagnosing facility and nearest mammography facility. Logistic multilevel models of late versus early stage were fitted, and odds ratios were calculated for travel times, controlling for age, race/ethnicity, census tract poverty, rural/urban residence, health insurance, and state random effects. Seventy-six percent of women in the study lived less than 20 min from their diagnosing facility, and 93 percent lived less than 20 min from the nearest mammography facility. Late stage at diagnosis was not associated with increasing travel time to diagnosing facility or nearest mammography facility. Diagnosis age under 50, Hispanic and Non-Hispanic Black race/ethnicity, high census tract poverty, and no health insurance were all significantly associated with late stage at diagnosis. Travel time to diagnosing facility or nearest mammography facility was not a determinant of late stage of breast cancer at diagnosis, and better geographic proximity did not assure more favorable stage distributions. Other factors beyond geographic proximity that can affect access should be evaluated more closely, including facility capacity, insurance acceptance, public transportation, and travel costs.

  8. Reducing employee travelling time through smart commuting

    International Nuclear Information System (INIS)

    Rahman, A N N A; Yusoff, Z M; Aziz, I S; Omar, D

    2014-01-01

    Extremely congested roads will definitely delay the arrival time of each trip.This certainly impacted the journey of employees. Tardiness at the workplace has become a perturbing issue for companies where traffic jams are the most common worker excuses. A depressing consequence on daily life and productivity of the employee occurs. The issues of commuting distance between workplace and resident area become the core point of this research. This research will emphasize the use of Geographical Information System (GIS) technique to explore the distance parameter to the employment area and will focus on the accessibility pattern of low-cost housing. The research methodology consists of interview sessions and a questionnaire to residents of low-cost housing areas in Melaka Tengah District in Malaysia. The combination of these processes will show the criteria from the selected parameter for each respondent from their resident area to the employment area. This will further help in the recommendation of several options for a better commute or improvement to the existing routes and public transportations system. Thus enhancing quality of life for employees and helping to reduce stress, decrease lateness, absenteeism and improving productivity in workplace

  9. Reducing employee travelling time through smart commuting

    Science.gov (United States)

    Rahman, A. N. N. A.; Yusoff, Z. M.; Aziz, I. S.; Omar, D.

    2014-02-01

    Extremely congested roads will definitely delay the arrival time of each trip.This certainly impacted the journey of employees. Tardiness at the workplace has become a perturbing issue for companies where traffic jams are the most common worker excuses. A depressing consequence on daily life and productivity of the employee occurs. The issues of commuting distance between workplace and resident area become the core point of this research. This research will emphasize the use of Geographical Information System (GIS) technique to explore the distance parameter to the employment area and will focus on the accessibility pattern of low-cost housing. The research methodology consists of interview sessions and a questionnaire to residents of low-cost housing areas in Melaka Tengah District in Malaysia. The combination of these processes will show the criteria from the selected parameter for each respondent from their resident area to the employment area. This will further help in the recommendation of several options for a better commute or improvement to the existing routes and public transportations system. Thus enhancing quality of life for employees and helping to reduce stress, decrease lateness, absenteeism and improving productivity in workplace.

  10. Time Spent in Home Production Activities by Married Couples and Single Adults with Children.

    Science.gov (United States)

    Douthitt, Robin A.

    1988-01-01

    A study found that, over time, married women employed full time have not decreased the time spent working in the home. Married men with young children have increased the time spent on home work. Single parents' time most closely resembled that of married women. (JOW)

  11. Bayesian Travel Time Inversion adopting Gaussian Process Regression

    Science.gov (United States)

    Mauerberger, S.; Holschneider, M.

    2017-12-01

    A major application in seismology is the determination of seismic velocity models. Travel time measurements are putting an integral constraint on the velocity between source and receiver. We provide insight into travel time inversion from a correlation-based Bayesian point of view. Therefore, the concept of Gaussian process regression is adopted to estimate a velocity model. The non-linear travel time integral is approximated by a 1st order Taylor expansion. A heuristic covariance describes correlations amongst observations and a priori model. That approach enables us to assess a proxy of the Bayesian posterior distribution at ordinary computational costs. No multi dimensional numeric integration nor excessive sampling is necessary. Instead of stacking the data, we suggest to progressively build the posterior distribution. Incorporating only a single evidence at a time accounts for the deficit of linearization. As a result, the most probable model is given by the posterior mean whereas uncertainties are described by the posterior covariance.As a proof of concept, a synthetic purely 1d model is addressed. Therefore a single source accompanied by multiple receivers is considered on top of a model comprising a discontinuity. We consider travel times of both phases - direct and reflected wave - corrupted by noise. Left and right of the interface are assumed independent where the squared exponential kernel serves as covariance.

  12. Investigating Unsaturated Zone Travel Times with Tritium and Stable Isotopes

    Science.gov (United States)

    Visser, A.; Thaw, M.; Van der Velde, Y.

    2017-12-01

    Travel times in the unsaturated zone are notoriously difficult to assess. Travel time tracers relying on the conservative transport of dissolved (noble) gases (tritium-helium, CFCs or SF6) are not applicable. Large water volume requirements of other cosmogenic radioactive isotopes (sulfur-35, sodium-22) preclude application in the unsaturated zone. Prior investigations have relied on models, introduced tracers, profiles of stable isotopes or tritium, or a combination of these techniques. Significant unsaturated zone travel times (UZTT) complicate the interpretation of stream water travel time tracers by ranked StorAge Selection (rSAS) functions. Close examination of rSAS functions in a sloping soil lysimeter[1] show the effect of the UZTT on the shape of the rSAS cumulative distribution function. We studied the UZTT at the Southern Sierra Critical Zone Observatory (SS-CZO) using profiles of tritium and stable isotopes (18O and 2H) in the unsaturated zone, supported by soil water content data. Tritium analyses require 100-500 mL of soil water and therefore large soil samples (1-5L), and elaborate laboratory procedures (oven drying, degassing and noble gas mass spectrometry). The high seasonal and interannual variability in precipitation of the Mediterranean climate, variable snow pack and high annual ET/P ratios lead to a dynamic hydrology in the deep unsaturated soils and regolith and highly variable travel time distributions. Variability of the tritium concentration in precipitation further complicates direct age estimates. Observed tritium profiles (>3 m deep) are interpreted in terms of advective and dispersive vertical transport of the input variability and radioactive decay of tritium. Significant unsaturated zone travel times corroborate previously observed low activities of short-lived cosmogenic radioactive nuclides in stream water. Under these conditions, incorporating the UZTT is critical to adequately reconstruct stream water travel time distributions. 1

  13. Time Spent on Social Network Sites and Psychological Well-Being: A Meta-Analysis.

    Science.gov (United States)

    Huang, Chiungjung

    2017-06-01

    This meta-analysis examines the relationship between time spent on social networking sites and psychological well-being factors, namely self-esteem, life satisfaction, loneliness, and depression. Sixty-one studies consisting of 67 independent samples involving 19,652 participants were identified. The mean correlation between time spent on social networking sites and psychological well-being was low at r = -0.07. The correlations between time spent on social networking sites and positive indicators (self-esteem and life satisfaction) were close to 0, whereas those between time spent on social networking sites and negative indicators (depression and loneliness) were weak. The effects of publication outlet, site on which users spent time, scale of time spent, and participant age and gender were not significant. As most included studies used student samples, future research should be conducted to examine this relationship for adults.

  14. Mind your travel ! Motivation, time use, and intent : Three factors of travel to be investigated

    OpenAIRE

    PAPON , Francis; Meissonnier , Joël

    2013-01-01

    The objective is to investigate the drivers of travel demand beyond the need to travel to destination; travellers may engage a trip for the sake of it, at least to some extent: travel includes a share of 'primary utility'. The paper focuses on two types of data and analysis: the primary utility of travel questions passed in the last French national travel survey, and eight dimensions of a trip proposed from a sociological analysis. The paper mixes these approaches and correlate survey answ...

  15. The Electric Traveling Salesman Problem with Time Windows

    DEFF Research Database (Denmark)

    Roberti, Roberto; Wen, Min

    2016-01-01

    To minimize greenhouse gas emissions, the logistic field has seen an increasing usage of electric vehicles. The resulting distribution planning problems present new computational challenges.We address a problem, called Electric Traveling Salesman Problem with Time Windows. We propose a mixed...

  16. A simple data fusion method for instantaneous travel time estimation

    NARCIS (Netherlands)

    Do, Michael; Pueboobpaphan, R.; Miska, Marc; Kuwahara, Masao; van Arem, Bart; Viegas, J.M.; Macario, R.

    2010-01-01

    Travel time is one of the most understandable parameters to describe traffic condition and an important input to many intelligent transportation systems applications. Direct measurement from Electronic Toll Collection (ETC) system is promising but the data arrives too late, only after the vehicles

  17. Seismic travel-time tomography for detailed global mantle structure

    NARCIS (Netherlands)

    Bijwaard, H.

    1999-01-01

    The object of this thesis is to use travel-time tomography to focus and enhance the existing global image of the Earth's mantle and crust. This image is still rather blurred with respect to the considerably sharper pictures commonly obtained in regional studies. The improvement is basically

  18. Seismic travel-time tomography for detailed global mantle structure

    NARCIS (Netherlands)

    Bijwaard, H.

    1999-01-01

    The object of this thesis is to use travel-time tomography to focus and enhance the existing global image of the Earth's mantle and crust. This image is still rather blurred with respect to the considerably sharper pictures commonly obtained in regional studies. The improvement is basically obtained

  19. Real-time traveler information market assessment white paper.

    Science.gov (United States)

    2010-02-22

    This report takes a multi-modal look at the lay of the land of the real-time traveler information : market in the United States. This includes identification and characterization of the gaps in the : domestic industry with respect to data cover...

  20. How to build a time machine: the real science of time travel

    CERN Document Server

    Clegg, Brian

    2013-01-01

    A pop science look at time travel technology, from Einstein to Ronald Mallett to present day experiments. Forget fiction: time travel is real.In How to Build a Time Machine, Brian Clegg provides an understanding of what time is and how it can be manipulated. He explores the fascinating world of physics and the remarkable possibilities of real time travel that emerge from quantum entanglement, superluminal speeds, neutron star cylinders and wormholes in space. With the fascinating paradoxes of time travel echoing in our minds will we realize that travel into the future might never be possible? Or will we realize there is no limit on what can be achieved, and take on this ultimate challenge? Only time will tell.

  1. DeepTravel: a Neural Network Based Travel Time Estimation Model with Auxiliary Supervision

    OpenAIRE

    Zhang, Hanyuan; Wu, Hao; Sun, Weiwei; Zheng, Baihua

    2018-01-01

    Estimating the travel time of a path is of great importance to smart urban mobility. Existing approaches are either based on estimating the time cost of each road segment which are not able to capture many cross-segment complex factors, or designed heuristically in a non-learning-based way which fail to utilize the existing abundant temporal labels of the data, i.e., the time stamp of each trajectory point. In this paper, we leverage on new development of deep neural networks and propose a no...

  2. ABSTRACT: CONTAMINANT TRAVEL TIMES FROM THE NEVADA TEST SITE TO YUCCA MOUNTAIN: SENSITIVITY TO POROSITY

    International Nuclear Information System (INIS)

    Karl F. Pohlmann; Jianting Zhu; Jenny B. Chapman; Charles E. Russell; Rosemary W. H. Carroll; David S. Shafer

    2008-01-01

    Yucca Mountain (YM), Nevada, has been proposed by the U.S. Department of Energy as a geologic repository for spent nuclear fuel and high-level radioactive waste. In this study, we investigate the potential for groundwater advective pathways from underground nuclear testing areas on the Nevada Test Site (NTS) to the YM area by estimating the timeframe for advective travel and its uncertainty resulting from porosity value uncertainty for hydrogeologic units (HGUs) in the region. We perform sensitivity analysis to determine the most influential HGUs on advective radionuclide travel times from the NTS to the YM area. Groundwater pathways and advective travel times are obtained using the particle tracking package MODPATH and flow results from the Death Valley Regional Flow System (DVRFS) model by the U.S. Geological Survey. Values and uncertainties of HGU porosities are quantified through evaluation of existing site porosity data and expert professional judgment and are incorporated through Monte Carlo simulations to estimate mean travel times and uncertainties. We base our simulations on two steady state flow scenarios for the purpose of long term prediction and monitoring. The first represents pre-pumping conditions prior to groundwater development in the area in 1912 (the initial stress period of the DVRFS model). The second simulates 1998 pumping (assuming steady state conditions resulting from pumping in the last stress period of the DVRFS model). Considering underground tests in a clustered region around Pahute Mesa on the NTS as initial particle positions, we track these particles forward using MODPATH to identify hydraulically downgradient groundwater discharge zones and to determine which flowpaths will intercept the YM area. Out of the 71 tests in the saturated zone, flowpaths of 23 intercept the YM area under the pre-pumping scenario. For the 1998 pumping scenario, flowpaths from 55 of the 71 tests intercept the YM area. The results illustrate that mean

  3. PTRACK: A particle tracking program for evaluation travel path/travel time uncertainties

    International Nuclear Information System (INIS)

    Thompson, B.M.; Campbell, J.E.; Longsine, D.E.

    1987-12-01

    PTRACK is a model which tracks the path of a radionuclide particle released from a nuclear waste repository into a ground-water flow system in a two-dimensional representation of stratified geologic medium. The code calculates the time required for the particle to travel from the release point (the edge of the disturbed zone) to the specified horizontal or vertical boundary (the accessible environment). The physical properties of the geologic setting and the ground-water flow system can be treated as fixed values or as random variables sampled from their respective probability distributions. In the latter case, PTRACK assigns a sampled value for each parameter and tracks a particle for this trial (realization) of the system. Repeated realizations allow the effects of parameter uncertainty on travel paths/travel times to be quantified. The code can also calculate partial correlation coefficients between dependent variables and independent variables, which are useful in identifying important independent variables. This documentation describes the mathematical basis for the model, the algorithms and solution techniques used, and the computer code design. It also contains a detailed user's manual. The implementation of PTRACK is verified with several systems for which solutions have been calculated by hand. The integration of PTRACK with a Latin hypercube sampling (LHS) code is also discussed, although other sampling methods can be employed in place of LHS. 11 refs., 14 figs., 22 tabs

  4. Heterogeneous Data Fusion Method to Estimate Travel Time Distributions in Congested Road Networks

    OpenAIRE

    Chaoyang Shi; Bi Yu Chen; William H. K. Lam; Qingquan Li

    2017-01-01

    Travel times in congested urban road networks are highly stochastic. Provision of travel time distribution information, including both mean and variance, can be very useful for travelers to make reliable path choice decisions to ensure higher probability of on-time arrival. To this end, a heterogeneous data fusion method is proposed to estimate travel time distributions by fusing heterogeneous data from point and interval detectors. In the proposed method, link travel time distributions are f...

  5. Real-time travel time prediction framework for departure time and route advice

    NARCIS (Netherlands)

    Calvert, S.C.; Snelder, M.; Bakri, T.; Heijligers, B.; Knoop, V.L.

    2015-01-01

    Heavily used urban networks remain a challenge for travel time prediction because traffic flow is rarely homogeneous and is also subject to a wide variety of disturbances. Various models, some of which use traffic flow theory and some of which are data driven, have been developed to predict traffic

  6. Estimation of Bimodal Urban Link Travel Time Distribution and Its Applications in Traffic Analysis

    Directory of Open Access Journals (Sweden)

    Yuxiong Ji

    2015-01-01

    Full Text Available Vehicles travelling on urban streets are heavily influenced by traffic signal controls, pedestrian crossings, and conflicting traffic from cross streets, which would result in bimodal travel time distributions, with one mode corresponding to travels without delays and the other travels with delays. A hierarchical Bayesian bimodal travel time model is proposed to capture the interrupted nature of urban traffic flows. The travel time distributions obtained from the proposed model are then considered to analyze traffic operations and estimate travel time distribution in real time. The advantage of the proposed bimodal model is demonstrated using empirical data, and the results are encouraging.

  7. Modelling travel and residence times in the eastern Irish Sea

    International Nuclear Information System (INIS)

    Dabrowski, T.; Hartnett, M.

    2008-01-01

    The Irish Sea, which lies between 51 deg. N-56 deg. N and 2 deg. 50'W-7 deg. W, provides a sheltered environment to exploit valuable fisheries resource. Anthropogenic activity is a real threat to its water quality. The majority of freshwater input down rivers flows into the eastern Irish Sea. The structure of the water circulation was not well understood during the planning of Sellafield nuclear plant outfall site in the eastern Irish Sea. A three-dimensional primitive equation numerical model was applied to the Irish Sea to simulate both barotropic and baroclinic circulation within the region. High accuracy was achieved with regard to the prediction of both tidal circulation and surface and nearbed water temperatures across the region. The model properly represented the Western Irish Sea Gyre, induced by thermal stratification and not known during planning Sellafield. Passive tracer simulations based on the developed hydrodynamic model were used to deliver residence times of the eastern Irish Sea region for various times of the year as well as travel times from the Sellafield outfall site to various locations within the Irish Sea. The results indicate a strong seasonal variability of travel times from Sellafield to the examined locations. Travel time to the Clyde Sea is the shortest for the autumnal tracer release (90 days); it takes almost a year for the tracer to arrive at the same location if it is released in January. Travel times from Sellafield to Dublin Bay fall within the range of 180-360 days. The average residence time of the entire eastern Irish Sea is around 7 months. The areas surrounding the Isle of Man are initially flushed due to a predominant northward flow; a backwater is formed in Liverpool Bay. Thus, elevated tracer concentrations are predicted in Liverpool Bay in the case of accidental spills at the Sellafield outfall site

  8. Mental time travel and the shaping of language.

    Science.gov (United States)

    Corballis, Michael C

    2009-01-01

    Episodic memory can be regarded as part of a more general system, unique to humans, for mental time travel, and the construction of future episodes. This allows more detailed planning than is afforded by the more general mechanisms of instinct, learning, and semantic memory. To be useful, episodic memory need not provide a complete or even a faithful record of past events, and may even be part of a process whereby we construct fictional accounts. The properties of language are aptly designed for the communication and sharing of episodes, and for the telling of stories; these properties include symbolic representation of the elements of real-world events, time markers, and combinatorial rules. Language and mental time travel probably co-evolved during the Pleistocene, when brain size increased dramatically.

  9. On the income elasticity of the value of travel time

    DEFF Research Database (Denmark)

    Börjesson, Maria; Fosgerau, Mogens; Algers, Staffan

    2012-01-01

    Transport infrastructure is long-term and in appraisal it is necessary to value travel time savings for future years. This requires knowing how the value of time (VTT) will develop over time as incomes grow. This paper investigates if the cross-sectional income elasticity of the VTT is equal...... to inter-temporal income elasticity. The study is based on two identical stated choice experiments conducted with a 13 year interval. Results indicate that the relationship between income and the VTT in the cross-section has remained unchanged over time. As a consequence, the inter-temporal income...... be expected to increase further over time....

  10. Investigating the distribution of the value of travel time savings

    DEFF Research Database (Denmark)

    Fosgerau, Mogens

    2006-01-01

    The distribution of the value of travel time savings (VTTS) is investigated employing various nonparametric techniques to a large dataset originating from a stated choice experiment. The data contain choices between a fast and more expensive alternative and a slow and less expensive alternative....... Increasing the implicit price of time leads to an increased share of respondents who decline to pay to save time. But a significant proportion of respondents, 13%, remain willing to pay to save time at the highest price of time in the design. This means that the right tail of the VTTS distribution...

  11. Time Spent, Workload, and Student and Faculty Perceptions in a Blended Learning Environment

    Science.gov (United States)

    Schumacher, Christie; Arif, Sally

    2016-01-01

    Objective. To evaluate student perception and time spent on asynchronous online lectures in a blended learning environment (BLE) and to assess faculty workload and perception. Methods. Students (n=427) time spent viewing online lectures was measured in three courses. Students and faculty members completed a survey to assess perceptions of a BLE. Faculty members recorded time spent creating BLEs. Results. Total time spent in the BLE was less than the allocated time for two of the three courses by 3-15%. Students preferred online lectures for their flexibility, students’ ability to apply information learned, and congruence with their learning styles. Faculty members reported the BLE facilitated higher levels of learning during class sessions but noted an increase in workload. Conclusion. A BLE increased faculty workload but was well received by students. Time spent viewing online lectures was less than what was allocated in two of the three courses. PMID:27667839

  12. Time machine tales the science fiction adventures and philosophical puzzles of time travel

    CERN Document Server

    Nahin, Paul J

    2017-01-01

    This book contains a broad overview of time travel in science fiction, along with a detailed examination of the philosophical implications of time travel. The emphasis of this book is now on the philosophical and on science fiction, rather than on physics, as in the author's earlier books on the subject. In that spirit there are, for example, no Tech Notes filled with algebra, integrals, and differential equations, as there are in the first and second editions of TIME MACHINES. Writing about time travel is, today, a respectable business. It hasn’t always been so. After all, time travel, prima facie, appears to violate a fundamental law of nature; every effect has a cause, with the cause occurring before the effect. Time travel to the past, however, seems to allow, indeed to demand, backwards causation, with an effect (the time traveler emerging into the past as he exits from his time machine) occurring before its cause (the time traveler pushing the start button on his machine’s control panel to start his...

  13. Teacher Time Spent on Student Health Issues and School Nurse Presence

    Science.gov (United States)

    Hill, Nina Jean; Hollis, Marianne

    2012-01-01

    Elementary school teacher time spent on student health issues and the relationship to school nurse services was the focus of this 2-year study. A cross-sectional design was used to survey traditional and exceptional (special needs) classroom teachers about the time they spent on health issues and their perception of school nurse presence. The…

  14. 48 CFR 852.271-72 - Time spent by counselee in counseling process.

    Science.gov (United States)

    2010-10-01

    ... counseling process. 852.271-72 Section 852.271-72 Federal Acquisition Regulations System DEPARTMENT OF... Clauses 852.271-72 Time spent by counselee in counseling process. As prescribed in 871.212, insert the following clause: Time Spent by Counselee in Counseling Process (APR 1984) The contractor agrees that no...

  15. The A-priori Traveling Salesman Problem with Time Windows

    DEFF Research Database (Denmark)

    Larsen, Allan; Madsen, Oli B.G.; Solomon, Marius M.

    2004-01-01

    seek to minimize lateness and examine the impact of this criterion choice on the distance traveled. Our focus on lateness is motivated by the problem faced by overnight mail service providers. We propose a real-time solution method that requires the vehicle, when idle, to wait at the current customer......In this paper we examine the traveling saleman problem with time windows for various degrees of dynamism. In contrast to the static problem, where the dispatcher can plan ahead, in the dynamic version, part or all of the necessary information becomes available only during the day of operation. We...... randomly generated data and on a real-world case study indicate that all policies proved capable of significantly reducing lateness. Our results also show that this can be accomplished with only small distance increases. The basic policy outperformed the other methods primarily when lateness and distance...

  16. Measuring the impact of efficient household travel decisions on potential travel time savings and accessibility gains

    Energy Technology Data Exchange (ETDEWEB)

    Recker, W.W.; McNally, M.G. [University of California, Irvine (United States). Institute of Transportation Studies, Department of Civil and Environmental Engineering; Chen, C. [Ming-Chuan University, Taiwan (China). Department of Tourism Industry

    2001-07-01

    Using the conceptual framework of time-space geography, this paper incorporates both spatio-temporal constraints and household interaction effects into a meaningful measure of the potential of a household to interact with the built environment. Within this context, personal accessibility is described as a measure of the potential ability of individuals within a household not only to reach activity opportunities, but to do so with sufficient time available for participation in those activities, subject to the spatio-temporal constraints imposed by their daily obligations and transportation supply environment. The incorporation of activity-based concepts in the measurement of accessibility as a product of travel time savings not only explicitly acknowledges a temporal dimension in assessing the potential for spatial interaction but also expands the applicability of accessibility consideration to such real-world policy options as the promotion of ride-sharing and trip chaining behaviors. An empirical application of the model system provides an indication of the potential of activity-based modeling approaches to assess the bounds on achievable improvements in accessibility and travel time based on daily household activity patterns. It also provides an assessment of roles for trip chaining and ride-sharing as potentially effective methods to facilitate transportation policy objectives. (author)

  17. Congestion relief by travel time minimization in near real time : Detroit area I-75 corridor study.

    Science.gov (United States)

    2008-12-01

    "This document summarizes the activities concerning the project: Congestion Relief by : Travel Time Minimization in Near Real Time -- Detroit Area I-75 Corridor Study since : the inception of the project (Nov. 22, 2006 through September 30, 2008). : ...

  18. Mental time travel: a case for evolutionary continuity.

    Science.gov (United States)

    Corballis, Michael C

    2013-01-01

    In humans, hippocampal activity responds to the imagining of past or future events. In rats, hippocampal activity is tied to particular locations in a maze, occurs after the animal has been in the maze, and sometimes corresponds to locations the animal did not actually visit. This suggests that mental time travel has neurophysiological underpinnings that go far back in evolution, and may not be, as some (including myself) have claimed, unique to humans. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Change of Measure between Light Travel Time and Euclidean Distances

    Directory of Open Access Journals (Sweden)

    Heymann Y.

    2013-04-01

    Full Text Available The problem of cosmological distances is approached using a method based on the propagation of light in an expanding Universe. From the chan ge of measure between Light Travel Time and Euclidean Distances, a formula is deri ved to compute distances as a function of redshift. This formula is identical to Matti g’s formula (with q 0 = 1 / 2 which is based on Friedmann’s equations of general relativi ty.

  20. Uncertainty analyses of unsaturated zone travel time at Yucca Mountain

    International Nuclear Information System (INIS)

    Nichols, W.E.; Freshley, M.D.

    1993-01-01

    Uncertainty analysis method can be applied to numerical models of ground-water flow to estimate the relative importance of physical and hydrologic input variables with respect to ground-water travel time. Monte Carlo numerical simulations of unsaturated flow in the Calico Hills nonwelded zeolitic (CHnz) layer at Yucca Mountain, Nevada, indicate that variability in recharge, and to a lesser extent in matrix porosity, explains most of the variability in predictions of water travel time through the unsaturated zone. Variations in saturated hydraulic conductivity and unsaturated curve-fitting parameters were not statistically significant in explaining variability in water travel time through the unsaturated CHnz unit. The results of this study suggest that the large uncertainty associated with recharge rate estimates for the Yucca Mountain site is of concern because the performance of the potential repository would be more sensitive to uncertainty in recharge than to any other parameter evaluated. These results are not exhaustive because of the limited site characterization data available and because of the preliminary nature of this study, which is limited to a single stratigraphic unit, one dimension, and does not account for fracture flow or other potential fast pathways at Yucca Mountain

  1. Travelling

    African Journals Online (AJOL)

    homes very soon becomes a misplaced sentiment. However well planned a journey may be and how- ever important and tiring the attendances at meet- ings are, at some stage of every day the traveller finds himself in an hotel room and loneliness starts closing in from all four walls. No matter how luxu- rious the hotel may ...

  2. Children's Experiences of Time when a Parent Travels for Work.

    Science.gov (United States)

    Zvonkovic, Anisa; Swenson, Andrea; Cornwell, Zoë

    2017-08-01

    This qualitative study focuses on different ways time is experienced by children in families who face time challenges due to a family member's job that required work travel. Data are from a family-level study that includes interviews of all family members over the age of 7. Using grounded theory methodology, this study illustrates ways in which job demands and family processes interact. Analysis centers on the 75 children's perspectives from 43 families. Holding together assessments of having enough time while wanting more time with their parents, children express emotion, generally unrecognized by parents, around the topic of family time. Children's experience of time with parents is rushed or calm, depending on the activities done in time and the gender of the parent with whom they spend time. Findings are interpreted through a feminist social constructionist lens.

  3. Travel time and concurrent-schedule choice: retrospective versus prospective control.

    OpenAIRE

    Davison, M; Elliffe, D

    2000-01-01

    Six pigeons were trained on concurrent variable-interval schedules in which two different travel times between alternatives, 4.5 and 0.5 s, were randomly arranged. In Part 1, the next travel time was signaled while the subjects were responding on each alternative. Generalized matching analyses of performance in the presence of the two travel-time signals showed significantly higher response and time sensitivity when the longer travel time was signaled compared to when the shorter time was sig...

  4. Time series analysis of travel trends in Vermont

    Science.gov (United States)

    Varna M. Ramaswamy; Walter F. Kuentzel

    1995-01-01

    Vermont's travel and tourism industry is not keeping pace with the nation-wide growth in the travel industry. While travel indicators such as domestic travel expenditures, tourism generated employment, payroll and tax receipts have been steadily increasing across the United States, these indicators in Vermont peaked in 1978 and have declined ever since. The state...

  5. Time spent in physical activity and sedentary behaviors on the working day: the American time use survey.

    Science.gov (United States)

    Tudor-Locke, Catrine; Leonardi, Claudia; Johnson, William D; Katzmarzyk, Peter T

    2011-12-01

    To determine time spent on the working day in sleep, work, sedentary behaviors, and light-, moderate-, and vigorous-intensity behaviors by occupation intensity. Data came from 30,758 working respondents to the 2003 to 2009 American Time Use Survey. Mean ± SEM time spent in work, sedentary behaviors, light-, moderate-, and vigorous-intensity activities, and sleep were computed by occupations classified as sedentary, light, moderate, and vigorous intensity. On average, approximately 32% of the 24-hour day was spent sleeping and approximately 31% was spent at work. Time spent in sedentary behaviors outside of work was higher, and light-intensity time was lower, with higher levels of intensity-defined occupation. Those employed in sedentary occupations were sedentary for approximately 11 hours per day, leaving little time to achieve recommended levels of physical activity for overall health.

  6. Using prospect theory to investigate the low value of travel time for small time changes

    DEFF Research Database (Denmark)

    Hjorth, Katrine; Fosgerau, Mogens

    A common finding in stated preference studies that measure the value of travel time (VTT), is that the measured per-minute VTT increases with the size of the time change considered, in conflict with standard neoclassical theory. The current paper tests prospect theory as a possible explanation......: More specifically, whether the phenomenon is generated by preferences being reference-dependent and exhibiting diminishing sensitivity for gains and losses, with a stronger degree of diminishing sensitivity for money than for travel time. We use stated preference data with trade-offs between travel...... time and money that pro- vide identification of the degrees of diminishing sensitivity for time and money gains and losses, thus enabling us to test and potentially falsify the prospect theory explanation. We apply a discrete choice model, in which choice depends on a reference-free value of travel...

  7. Developer’s time spent in a software project part using the SGD framework

    OpenAIRE

    Ciesluk, Simon

    2016-01-01

    Resource management is important for software projects to be successful. Time is one of these resources that needs to be managed. To do this you need to know how time resources are spent. Currently the existence of published material on time resources spent in a software project is almost none. In this thesis a research was conducted on how time resources are spent by an individual developer in a software project. The Self-Governance Developer framework was the tool used to gather these resou...

  8. Travelling waves in expanding spatially homogeneous space–times

    International Nuclear Information System (INIS)

    Alekseev, George

    2015-01-01

    Some classes of the so-called ‘travelling wave’ solutions of Einstein and Einstein–Maxwell equations in general relativity and of dynamical equations for massless bosonic fields in string gravity in four and higher dimensions are presented. Similarly to the well known plane-fronted waves with parallel rays (pp-waves), these travelling wave solutions may depend on arbitrary functions of a null coordinate which determine the arbitrary profiles and polarizations of the waves. However, in contrast with pp-waves, these waves do not admit the null Killing vector fields and can exist in some curved (expanding and spatially homogeneous) background space–times, where these waves propagate in certain directions without any scattering. Mathematically, some of these classes of solutions arise as the fixed points of Kramer–Neugebauer transformations for hyperbolic integrable reductions of the above mentioned field equations or, in other cases, after imposing the ansatz that these waves do not change the part of the spatial metric transverse to the direction of wave propagation. It is worth noting that the strikingly simple forms of all the solutions presented prospectively make possible the consideration of the nonlinear interaction of these waves with the background curvature and singularities, as well as the collision of such wave pulses with solitons or with each other in the backgrounds where such travelling waves may exist. (paper)

  9. A comparative analysis of short-range travel time prediction methods

    NARCIS (Netherlands)

    Huisken, Giovanni; van Berkum, Eric C.

    2003-01-01

    Increasing car mobility has lead to an increasing demand for traffic information. This contribution deals with information about travel times. When car drivers are provided with this type of information, the travel times should ideally be the times that they will encounter. As a result travel times

  10. Online travel time estimation in urban areas using the occupancy of long loop detectors

    NARCIS (Netherlands)

    Mak, W.K.; Viti, F.; Hoogendoorn, S.P.; Hegyi, A.

    2010-01-01

    Roads in the Netherlands are often heavily congested. Real-time travel time information can be a valuable instrument to reduce the impact of increasing traffic demand on travel time with advantages for traffic participants as well as for the traffic network managers. For urban roads travel time

  11. Innovative methods for calculation of freeway travel time using limited data : final report.

    Science.gov (United States)

    2008-01-01

    Description: Travel time estimations created by processing of simulated freeway loop detector data using proposed method have been compared with travel times reported from VISSIM model. An improved methodology was proposed to estimate freeway corrido...

  12. A travel time forecasting model based on change-point detection method

    Science.gov (United States)

    LI, Shupeng; GUANG, Xiaoping; QIAN, Yongsheng; ZENG, Junwei

    2017-06-01

    Travel time parameters obtained from road traffic sensors data play an important role in traffic management practice. A travel time forecasting model is proposed for urban road traffic sensors data based on the method of change-point detection in this paper. The first-order differential operation is used for preprocessing over the actual loop data; a change-point detection algorithm is designed to classify the sequence of large number of travel time data items into several patterns; then a travel time forecasting model is established based on autoregressive integrated moving average (ARIMA) model. By computer simulation, different control parameters are chosen for adaptive change point search for travel time series, which is divided into several sections of similar state.Then linear weight function is used to fit travel time sequence and to forecast travel time. The results show that the model has high accuracy in travel time forecasting.

  13. Construction and installation of travel time signs on I-35 in Austin.

    Science.gov (United States)

    2016-08-01

    Dynamic travel time signs (DTTS) provide current travel times to a specific destination via one or more : routes. These signs aid motorists in making route choice decisions en route. Through this project, three : DTTS were fabricated and installed on...

  14. Freeway travel time estimation using existing fixed traffic sensors : phase 2.

    Science.gov (United States)

    2015-03-01

    Travel time, one of the most important freeway performance metrics, can be easily estimated using the : data collected from fixed traffic sensors, avoiding the need to install additional travel time data collectors. : This project is aimed at fully u...

  15. DOTD support for UTC project : travel time estimation using bluetooth, [research project capsule].

    Science.gov (United States)

    2013-10-01

    Travel time estimates are useful tools for measuring congestion in an urban area. Current : practice involves using probe vehicles or video cameras to measure travel time, but this is a laborintensive and expensive means of obtaining the information....

  16. Arterial link travel time estimation using loop detector data : phase 1

    Science.gov (United States)

    1997-11-01

    The envisioned operational tests of Advanced Traveler Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS) in the Minneapolis/St. Paul area call for the provision of timely and reliable travel times over an entire rod network. Un...

  17. Completion of construction and installation of travel time signs on I-35 in Austin : project summary.

    Science.gov (United States)

    2015-08-31

    Drivers desire real-time information when : traveling in order to make route choice : decisions. One type of information that can be : provided is current (dynamic) travel times on : two possible routes that serve a common : destination. In this way,...

  18. Validation and augmentation of Inrix arterial travel time data using independent sources.

    Science.gov (United States)

    2015-02-01

    Travel time data is a key input to Intelligent Transportation Systems (ITS) applications. Advancement in vehicle : tracking and identification technologies and proliferation of location-aware and connected devices has made network-wide travel time da...

  19. Comparison of methods for measuring travel time at Florida freeways and arterials.

    Science.gov (United States)

    2014-07-01

    Travel time is an important performance measure used to assess the traffic operational quality of various types of highway : facilities. Previous research funded by the Florida Department of Transportation (FDOT) on travel time reliability developed,...

  20. Assessing segment- and corridor-based travel-time reliability on urban freeways : final report.

    Science.gov (United States)

    2016-09-01

    Travel time and its reliability are intuitive performance measures for freeway traffic operations. The objective of this project was to quantify segment-based and corridor-based travel time reliability measures on urban freeways. To achieve this obje...

  1. Vehicle routing with stochastic time-dependent travel times

    NARCIS (Netherlands)

    Lecluyse, C.; Woensel, van T.; Peremans, H.

    2009-01-01

    Assigning and scheduling vehicle routes in a stochastic time-dependent environment is a crucial management problem. The assumption that in a real-life environment everything goes according to an a priori determined static schedule is unrealistic. Our methodology builds on earlier work in which the

  2. Vehicle routing with stochastic time-dependent travel times

    NARCIS (Netherlands)

    Lecluyse, C.; Woensel, van T.; Peremans, H.

    2007-01-01

    Assigning and scheduling vehicle routes in a stochastic time-dependent environment is a crucial management problem. The assumption that in a real-life environment everything goes according to an a priori determined static schedule is unrealistic. Our methodology builds on earlier work in which the

  3. Evaluation of a real-time travel time prediction system in a freeway construction work zone : final report, March 2001.

    Science.gov (United States)

    2001-03-01

    A real-time travel time prediction system (TIPS) was evaluated in a construction work zone. TIPS includes changeable message signs (CMSs) displaying the travel time and distance to the end of the work zone to motorists. The travel times displayed by ...

  4. Evaluation of a real-time travel time prediction system in a freeway construction work zone : executive summary.

    Science.gov (United States)

    2001-03-01

    A real-time travel time prediction system (TIPS) was evaluated in a construction work : zone. TIPS includes changeable message signs (CMSs) displaying the travel time and : distance to the end of the work zone to motorists. The travel times displayed...

  5. Assessment and refinement of real-time travel time algorithms for use in practice : final report, October 2008.

    Science.gov (United States)

    2008-10-01

    The FHWA has strongly encouraged transportation departments to display travel times on their Dynamic Message Signs (DMS). The Oregon : Department of Transportation (ODOT) currently displays travel time estimates on three DMSs in the Portland metropol...

  6. Monitoring travel times in an urban network using video, GPS and Bluetooth

    NARCIS (Netherlands)

    Jie, L.; Van Zuylen, H.J.; Chunhua, L.; Shoufeng, L.

    2011-01-01

    The travel time is an important measure for the quality of traffic. This paper discusses a few methods to measure or estimate the travel time in urban road networks. First of all, it is important to know that urban travel times display a large variation, so that the measurement of a single (average)

  7. A methodological framework of travel time distribution estimation for urban signalized arterial roads

    NARCIS (Netherlands)

    Zheng, Fangfang; van Zuylen, H.J.; Liu, Xiaobo

    2017-01-01

    Urban travel times are rather variable as a result of a lot of stochastic factors both in traffic flows, signals, and other conditions on the infrastructure. However, the most common way both in literature and practice is to estimate or predict only expected travel times, not travel time

  8. Wireless data collection system for travel time estimation and traffic performance evaluation.

    Science.gov (United States)

    2010-09-01

    Having accurate and continually updated travel time and other performance data for the road and highway system has many benefits. From the perspective of the road users, having real-time updates on travel times will permit better travel and route pla...

  9. Trip-oriented travel time prediction (TOTTP) with historical vehicle trajectories

    Science.gov (United States)

    Xu, Tao; Li, Xiang; Claramunt, Christophe

    2018-06-01

    Accurate travel time prediction is undoubtedly of importance to both traffic managers and travelers. In highly-urbanized areas, trip-oriented travel time prediction (TOTTP) is valuable to travelers rather than traffic managers as the former usually expect to know the travel time of a trip which may cross over multiple road sections. There are two obstacles to the development of TOTTP, including traffic complexity and traffic data coverage.With large scale historical vehicle trajectory data and meteorology data, this research develops a BPNN-based approach through integrating multiple factors affecting trip travel time into a BPNN model to predict trip-oriented travel time for OD pairs in urban network. Results of experiments demonstrate that it helps discover the dominate trends of travel time changes daily and weekly, and the impact of weather conditions is non-trivial.

  10. The Regularity and Irregularity of Travel: an Analysis of the Consistency of Travel Times Associated with Subsistence, Maintenance and Discretionary Activities

    OpenAIRE

    Longden, Thomas

    2016-01-01

    Regular and irregular travel patterns coincide with different underlying purposes of travel and days of the week. Within this paper, it is shown that the balance between subsistence (i.e. work) and discretionary (i.e. leisure) activities is related to differences in travel patterns and explains consistency across years. Using eight years of time use diary entries this paper finds that travel time related to subsistence activities tends to be regular and stable. In contrast, travel time associ...

  11. Time and travel costs incurred by women attending antenatal tests: A costing study.

    Science.gov (United States)

    Verhoef, Talitha I; Daley, Rebecca; Vallejo-Torres, Laura; Chitty, Lyn S; Morris, Stephen

    2016-09-01

    to estimate the costs to women, their friends and family for different antenatal tests in the Down's syndrome (DS) screening pathway. questionnaire-based costing study. eight maternity clinics across the UK. pregnant women (n=574) attending an appointment for DS screening, NIPT or invasive testing between December 2013 and September 2014. using data collected from the questionnaires we calculated the total costs to women by multiplying the time spent at the hospital and travelling to and from it by the opportunity costs of the women and accompanying person and adding travel and childcare costs. Assumptions about the value of opportunity costs were tested in one-way sensitivity analyses. The main outcome measure was the mean cost to the women and friends/family for each test (DS screening, NIPT, and invasive testing). mean costs to women and their family/friend were £33.96 per visit, of which £22.47 were time costs, £9.15 were travel costs and £2.34 were childcare costs. Costs were lowest for NIPT (£22), £32 for DS screening (£44 if combined with NIPT), and highest for invasive testing (£60). Sensitivity analysis revealed that variations around the value of leisure time opportunity costs had the largest influence on the results. there are considerable costs to women, their friends and family when attending different tests in the DS screening pathway. when assessing the cost-effectiveness of changes to this pathway, costs to women should be considered. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Nonlinear time-dependent simulation of helix traveling wave tubes

    International Nuclear Information System (INIS)

    Peng Wei-Feng; Yang Zhong-Hai; Hu Yu-Lu; Li Jian-Qing; Lu Qi-Ru; Li Bin

    2011-01-01

    A one-dimensional nonlinear time-dependent theory for helix traveling wave tubes is studied. A generalized electromagnetic field is applied to the expression of the radio frequency field. To simulate the variations of the high frequency structure, such as the pitch taper and the effect of harmonics, the spatial average over a wavelength is substituted by a time average over a wave period in the equation of the radio frequency field. Under this assumption, the space charge field of the electron beam can be treated by a space charge wave model along with the space charge coefficient. The effects of the radio frequency and the space charge fields on the electrons are presented by the equations of the electron energy and the electron phase. The time-dependent simulation is compared with the frequency-domain simulation for a helix TWT, which validates the availability of this theory. (interdisciplinary physics and related areas of science and technology)

  13. Valuation of Travel Time Savings in Viewpoint of WTA

    Science.gov (United States)

    Shao, Chang-qiao; Liu, Yang; Liu, Xiao-ming

    2014-01-01

    In order to investigate the issues in measurement of value of travel time savings (VTTS), the willingness-to-accept (WTA) for the private car owner is studied by using surveyed data. It is convincing that trip purpose, trip length, time savings, cost savings, income, and allowance from employee have effects on the WTA. Moreover, influences of these variables are not the same for different trip purposes. For commuting trips, effects of income and allowance from employee are significant while time savings and cost savings are dominated for leisure and shopping trips. It is also found that WTA is much higher than expected which implies that there are a group of drivers who are not prone to switching to other trip modes other than passenger car. PMID:25530751

  14. Valuation of travel time savings in viewpoint of WTA.

    Science.gov (United States)

    Shao, Chang-Qiao; Liu, Yang; Liu, Xiao-Ming

    2014-01-01

    In order to investigate the issues in measurement of value of travel time savings (VTTS), the willingness-to-accept (WTA) for the private car owner is studied by using surveyed data. It is convincing that trip purpose, trip length, time savings, cost savings, income, and allowance from employee have effects on the WTA. Moreover, influences of these variables are not the same for different trip purposes. For commuting trips, effects of income and allowance from employee are significant while time savings and cost savings are dominated for leisure and shopping trips. It is also found that WTA is much higher than expected which implies that there are a group of drivers who are not prone to switching to other trip modes other than passenger car.

  15. Valuation of Travel Time Savings in Viewpoint of WTA

    Directory of Open Access Journals (Sweden)

    Chang-qiao Shao

    2014-01-01

    Full Text Available In order to investigate the issues in measurement of value of travel time savings (VTTS, the willingness-to-accept (WTA for the private car owner is studied by using surveyed data. It is convincing that trip purpose, trip length, time savings, cost savings, income, and allowance from employee have effects on the WTA. Moreover, influences of these variables are not the same for different trip purposes. For commuting trips, effects of income and allowance from employee are significant while time savings and cost savings are dominated for leisure and shopping trips. It is also found that WTA is much higher than expected which implies that there are a group of drivers who are not prone to switching to other trip modes other than passenger car.

  16. Uncertain travel times and activity schedules under conditions of space-time constraints and invariant choice heuristics

    NARCIS (Netherlands)

    Rasouli, S.; Timmermans, H.J.P.

    2014-01-01

    The aim of this paper is to assess the impact of uncertain travel times as reflected in travel time variability on the outcomes of individuals’ activity–travel scheduling decisions, assuming they are faced with fixed space–time constraints and apply the set of decision rules that they have developed

  17. Comparison of Travel-Time and Amplitude Measurements for Deep-Focusing Time-Distance Helioseismology

    Science.gov (United States)

    Pourabdian, Majid; Fournier, Damien; Gizon, Laurent

    2018-04-01

    The purpose of deep-focusing time-distance helioseismology is to construct seismic measurements that have a high sensitivity to the physical conditions at a desired target point in the solar interior. With this technique, pairs of points on the solar surface are chosen such that acoustic ray paths intersect at this target (focus) point. Considering acoustic waves in a homogeneous medium, we compare travel-time and amplitude measurements extracted from the deep-focusing cross-covariance functions. Using a single-scattering approximation, we find that the spatial sensitivity of deep-focusing travel times to sound-speed perturbations is zero at the target location and maximum in a surrounding shell. This is unlike the deep-focusing amplitude measurements, which have maximum sensitivity at the target point. We compare the signal-to-noise ratio for travel-time and amplitude measurements for different types of sound-speed perturbations, under the assumption that noise is solely due to the random excitation of the waves. We find that, for highly localized perturbations in sound speed, the signal-to-noise ratio is higher for amplitude measurements than for travel-time measurements. We conclude that amplitude measurements are a useful complement to travel-time measurements in time-distance helioseismology.

  18. NOTE ON TRAVEL TIME SHIFTS DUE TO AMPLITUDE MODULATION IN TIME-DISTANCE HELIOSEISMOLOGY MEASUREMENTS

    International Nuclear Information System (INIS)

    Nigam, R.; Kosovichev, A. G.

    2010-01-01

    Correct interpretation of acoustic travel times measured by time-distance helioseismology is essential to get an accurate understanding of the solar properties that are inferred from them. It has long been observed that sunspots suppress p-mode amplitude, but its implications on travel times have not been fully investigated so far. It has been found in test measurements using a 'masking' procedure, in which the solar Doppler signal in a localized quiet region of the Sun is artificially suppressed by a spatial function, and using numerical simulations that the amplitude modulations in combination with the phase-speed filtering may cause systematic shifts of acoustic travel times. To understand the properties of this procedure, we derive an analytical expression for the cross-covariance of a signal that has been modulated locally by a spatial function that has azimuthal symmetry and then filtered by a phase-speed filter typically used in time-distance helioseismology. Comparing this expression to the Gabor wavelet fitting formula without this effect, we find that there is a shift in the travel times that is introduced by the amplitude modulation. The analytical model presented in this paper can be useful also for interpretation of travel time measurements for the non-uniform distribution of oscillation amplitude due to observational effects.

  19. Evaluating effectiveness of real-time advanced traveler information systems using a small test vehicle fleet

    Science.gov (United States)

    1997-01-01

    ADVANCE was an in-vehicle advanced traveler information system (ATIS) providing route guidance in real time that operated in the northwestern portion and northwest suburbs of Chicago, Illinois. It used probe vehicles to generate dynamically travel ti...

  20. Using prospect theory to investigate the low marginal value of travel time for small time changes

    DEFF Research Database (Denmark)

    Hjorth, Katrine; Fosgerau, Mogens

    2012-01-01

    A common finding in stated preference studies that measure the value of travel time (VTT) is that the measured VTT increases with the size of the time change considered, in conflict with standard neoclassical economic theory. We present a new test of a possible explanation for the phenomenon...... that builds on the diminishing or constant sensitivity of the value functions in prospect theory.We use stated preference data with trade-offs between travel time and money that provide separate identification of the degrees of diminishing sensitivity for time and money gains and losses. This enables us...

  1. Heterogeneous Data Fusion Method to Estimate Travel Time Distributions in Congested Road Networks

    Directory of Open Access Journals (Sweden)

    Chaoyang Shi

    2017-12-01

    Full Text Available Travel times in congested urban road networks are highly stochastic. Provision of travel time distribution information, including both mean and variance, can be very useful for travelers to make reliable path choice decisions to ensure higher probability of on-time arrival. To this end, a heterogeneous data fusion method is proposed to estimate travel time distributions by fusing heterogeneous data from point and interval detectors. In the proposed method, link travel time distributions are first estimated from point detector observations. The travel time distributions of links without point detectors are imputed based on their spatial correlations with links that have point detectors. The estimated link travel time distributions are then fused with path travel time distributions obtained from the interval detectors using Dempster-Shafer evidence theory. Based on fused path travel time distribution, an optimization technique is further introduced to update link travel time distributions and their spatial correlations. A case study was performed using real-world data from Hong Kong and showed that the proposed method obtained accurate and robust estimations of link and path travel time distributions in congested road networks.

  2. Heterogeneous Data Fusion Method to Estimate Travel Time Distributions in Congested Road Networks.

    Science.gov (United States)

    Shi, Chaoyang; Chen, Bi Yu; Lam, William H K; Li, Qingquan

    2017-12-06

    Travel times in congested urban road networks are highly stochastic. Provision of travel time distribution information, including both mean and variance, can be very useful for travelers to make reliable path choice decisions to ensure higher probability of on-time arrival. To this end, a heterogeneous data fusion method is proposed to estimate travel time distributions by fusing heterogeneous data from point and interval detectors. In the proposed method, link travel time distributions are first estimated from point detector observations. The travel time distributions of links without point detectors are imputed based on their spatial correlations with links that have point detectors. The estimated link travel time distributions are then fused with path travel time distributions obtained from the interval detectors using Dempster-Shafer evidence theory. Based on fused path travel time distribution, an optimization technique is further introduced to update link travel time distributions and their spatial correlations. A case study was performed using real-world data from Hong Kong and showed that the proposed method obtained accurate and robust estimations of link and path travel time distributions in congested road networks.

  3. Time Spent Outdoors, Depressive Symptoms, and Variation by Race and Ethnicity.

    Science.gov (United States)

    Beyer, Kirsten M M; Szabo, Aniko; Nattinger, Ann B

    2016-09-01

    Numerous studies have explored neighborhood environmental correlates of mental illnesses, presuming that the time individuals spend in their environment can confer benefit or harm based on environmental characteristics. However, few population-based studies have directly examined the relationship between time spent outdoors and mental health, and little work has been done to explore how experiences differ by race and ethnicity. Though some have proposed "doses of outdoor time" to improve health, the absence of information about the benefits conferred by particular "doses," and expected baseline levels of outdoor time, are needed to inform the development of recommendations and interventions. This study examined the relationship between time spent outdoors and depression among a population-based sample of American adults, characterized current levels of time spent outdoors by race and ethnicity, and examined how the relationship between time spent outdoors and depression varies by race and ethnicity. Descriptive statistics and survey regression models were used to examine data from the National Health and Nutrition Examination Survey for 2009-2012. Findings provide evidence that time spent outdoors is associated with fewer depressive symptoms, but this benefit may not be equally distributed by race and ethnicity. Descriptive analyses also reveal differences in time spent outdoors among different racial and ethnic groups. Study findings support the notion that increasing time spent outdoors may result in mental health benefits. However, this study questions whether that benefit is experienced equally among different groups, particularly given differences in occupational experiences and environmental characteristics of neighborhoods. Copyright © 2016 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

  4. Using travel times to simulate multi-dimensional bioreactive transport in time-periodic flows.

    Science.gov (United States)

    Sanz-Prat, Alicia; Lu, Chuanhe; Finkel, Michael; Cirpka, Olaf A

    2016-04-01

    In travel-time models, the spatially explicit description of reactive transport is replaced by associating reactive-species concentrations with the travel time or groundwater age at all locations. These models have been shown adequate for reactive transport in river-bank filtration under steady-state flow conditions. Dynamic hydrological conditions, however, can lead to fluctuations of infiltration velocities, putting the validity of travel-time models into question. In transient flow, the local travel-time distributions change with time. We show that a modified version of travel-time based reactive transport models is valid if only the magnitude of the velocity fluctuates, whereas its spatial orientation remains constant. We simulate nonlinear, one-dimensional, bioreactive transport involving oxygen, nitrate, dissolved organic carbon, aerobic and denitrifying bacteria, considering periodic fluctuations of velocity. These fluctuations make the bioreactive system pulsate: The aerobic zone decreases at times of low velocity and increases at those of high velocity. For the case of diurnal fluctuations, the biomass concentrations cannot follow the hydrological fluctuations and a transition zone containing both aerobic and obligatory denitrifying bacteria is established, whereas a clear separation of the two types of bacteria prevails in the case of seasonal velocity fluctuations. We map the 1-D results to a heterogeneous, two-dimensional domain by means of the mean groundwater age for steady-state flow in both domains. The mapped results are compared to simulation results of spatially explicit, two-dimensional, advective-dispersive-bioreactive transport subject to the same relative fluctuations of velocity as in the one-dimensional model. The agreement between the mapped 1-D and the explicit 2-D results is excellent. We conclude that travel-time models of nonlinear bioreactive transport are adequate in systems of time-periodic flow if the flow direction does not change

  5. Time spent on home food preparation and indicators of healthy eating.

    Science.gov (United States)

    Monsivais, Pablo; Aggarwal, Anju; Drewnowski, Adam

    2014-12-01

    The amount of time spent on food preparation and cooking may have implications for diet quality and health. However, little is known about how food-related time use relates to food consumption and spending, either at restaurants or for food consumed at home. To quantitatively assess the associations among the amount of time habitually spent on food preparation and patterns of self-reported food consumption, food spending, and frequency of restaurant use. This was a cross-sectional study of 1,319 adults in a population-based survey conducted in 2008-2009. The sample was stratified into those who spent 2 hours/day on food preparation and cleanup. Descriptive statistics and multivariable regression models examined differences between time-use groups. Analyses were conducted in 2011-2013. Individuals who spent the least amount of time on food preparation tended to be working adults who placed a high priority on convenience. Greater amount of time spent on home food preparation was associated with indicators of higher diet quality, including significantly more frequent intake of vegetables, salads, fruits, and fruit juices. Spending food preparation was associated with significantly more money spent on food away from home and more frequent use of fast food restaurants compared to those who spent more time on food preparation. The findings indicate that time might be an essential ingredient in the production of healthier eating habits among adults. Further research should investigate the determinants of spending time on food preparation. Copyright © 2014 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

  6. Foreign travel report: Visits to UK, Belgium, Germany, and France to benchmark European spent fuel and waste management technology

    International Nuclear Information System (INIS)

    Ermold, L.F.; Knecht, D.A.

    1993-08-01

    The ICPP WINCO Spent Fuel and Waste Management Development Program recently was funded by DOE-EM to develop new technologies for immobilizing ICPP spent fuels, sodium-bearing liquid waste, and calcine to a form suitable for disposal. European organizations are heavily involved, in some cases on an industrial scale in areas of waste management, including spent fuel disposal and HLW vitrification. The purpose of this trip was to acquire first-hand European efforts in handling of spent reactor fuel and nuclear waste management, including their processing and technical capabilities as well as their future planning. Even though some differences exist in European and U.S. DOE waste compositions and regulations, many aspects of the European technologies may be applicable to the U.S. efforts, and several areas offer potential for technical collaboration

  7. Foreign travel report: Visits to UK, Belgium, Germany, and France to benchmark European spent fuel and waste management technology

    Energy Technology Data Exchange (ETDEWEB)

    Ermold, L.F.; Knecht, D.A.

    1993-08-01

    The ICPP WINCO Spent Fuel and Waste Management Development Program recently was funded by DOE-EM to develop new technologies for immobilizing ICPP spent fuels, sodium-bearing liquid waste, and calcine to a form suitable for disposal. European organizations are heavily involved, in some cases on an industrial scale in areas of waste management, including spent fuel disposal and HLW vitrification. The purpose of this trip was to acquire first-hand European efforts in handling of spent reactor fuel and nuclear waste management, including their processing and technical capabilities as well as their future planning. Even though some differences exist in European and U.S. DOE waste compositions and regulations, many aspects of the European technologies may be applicable to the U.S. efforts, and several areas offer potential for technical collaboration.

  8. Suburb-to-suburb intercity travel: Energy, time and dollar expenditures

    Science.gov (United States)

    Fels, M. F.

    1976-01-01

    The effect of adding suburb to terminal and terminal to suburb travel is examined. The energy consumed in entire trips was estimated. The total energy costs are compared with total travel times, and dollar costs to the traveler. Trips between origins in seven suburbs of Newark, New Jersey and destinations in two Washington, D. C. suburbs are analyzed.

  9. It takes longer than you think: librarian time spent on systematic review tasks*

    Science.gov (United States)

    Bullers, Krystal; Howard, Allison M.; Hanson, Ardis; Kearns, William D.; Orriola, John J.; Polo, Randall L.; Sakmar, Kristen A.

    2018-01-01

    Introduction The authors examined the time that medical librarians spent on specific tasks for systematic reviews (SRs): interview process, search strategy development, search strategy translation, documentation, deliverables, search methodology writing, and instruction. We also investigated relationships among the time spent on SR tasks, years of experience, and number of completed SRs to gain a better understanding of the time spent on SR tasks from time, staffing, and project management perspectives. Methods A confidential survey and study description were sent to medical library directors who were members of the Association of Academic Health Sciences Libraries as well as librarians serving members of the Association of American Medical Colleges or American Osteopathic Association. Results Of the 185 participants, 143 (77%) had worked on an SR within the last 5 years. The number of SRs conducted by participants during their careers ranged from 1 to 500, with a median of 5. The major component of time spent was on search strategy development and translation. Average aggregated time for standard tasks was 26.9 hours, with a median of 18.5 hours. Task time was unrelated to the number of SRs but was positively correlated with years of SR experience. Conclusion The time required to conduct the librarian’s discrete tasks in an SR varies substantially, and there are no standard time frames. Librarians with more SR experience spent more time on instruction and interviews; time spent on all other tasks varied widely. Librarians also can expect to spend a significant amount of their time on search strategy development, translation, and writing. PMID:29632442

  10. Travel Times for Screening Mammography: Impact of Geographic Expansion by a Large Academic Health System.

    Science.gov (United States)

    Rosenkrantz, Andrew B; Liang, Yu; Duszak, Richard; Recht, Michael P

    2017-09-01

    This study aims to assess the impact of off-campus facility expansion by a large academic health system on patient travel times for screening mammography. Screening mammograms performed from 2013 to 2015 and associated patient demographics were identified using the NYU Langone Medical Center Enterprise Data Warehouse. During this time, the system's number of mammography facilities increased from 6 to 19, reflecting expansion beyond Manhattan throughout the New York metropolitan region. Geocoding software was used to estimate driving times from patients' homes to imaging facilities. For 147,566 screening mammograms, the mean estimated patient travel time was 19.9 ± 15.2 minutes. With facility expansion, travel times declined significantly (P travel times between such subgroups. However, travel times to pre-expansion facilities remained stable (initial: 26.8 ± 18.9 minutes, final: 26.7 ± 18.6 minutes). Among women undergoing mammography before and after expansion, travel times were shorter for the postexpansion mammogram in only 6.3%, but this rate varied significantly (all P travel burden and reduce travel time variation among sociodemographic populations. Nonetheless, existing patients strongly tend to return to established facilities despite potentially shorter travel time locations, suggesting strong site loyalty. Variation in travel times likely relates to various factors other than facility proximity. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  11. Age at Menarche and Time Spent in Education: A Mendelian Randomization Study.

    Science.gov (United States)

    Gill, D; Del Greco M, F; Rawson, T M; Sivakumaran, P; Brown, A; Sheehan, N A; Minelli, C

    2017-09-01

    Menarche signifies the primary event in female puberty and is associated with changes in self-identity. It is not clear whether earlier puberty causes girls to spend less time in education. Observational studies on this topic are likely to be affected by confounding environmental factors. The Mendelian randomization (MR) approach addresses these issues by using genetic variants (such as single nucleotide polymorphisms, SNPs) as proxies for the risk factor of interest. We use this technique to explore whether there is a causal effect of age at menarche on time spent in education. Instruments and SNP-age at menarche estimates are identified from a Genome Wide Association Study (GWAS) meta-analysis of 182,416 women of European descent. The effects of instruments on time spent in education are estimated using a GWAS meta-analysis of 118,443 women performed by the Social Science Genetic Association Consortium (SSGAC). In our main analysis, we demonstrate a small but statistically significant causal effect of age at menarche on time spent in education: a 1 year increase in age at menarche is associated with 0.14 years (53 days) increase in time spent in education (95% CI 0.10-0.21 years, p = 3.5 × 10 -8 ). The causal effect is confirmed in sensitivity analyses. In identifying this positive causal effect of age at menarche on time spent in education, we offer further insight into the social effects of puberty in girls.

  12. Predicting Time Spent in Treatment in a Sample of Danish Survivors of Child Sexual Abuse.

    Science.gov (United States)

    Fletcher, Shelley; Elklit, Ask; Shevlin, Mark; Armour, Cherie

    2017-07-01

    The aim of this study was to identify significant predictors of length of time spent in treatment. In a convenience sample of 439 Danish survivors of child sexual abuse, predictors of time spent in treatment were examined. Assessments were conducted on a 6-month basis over a period of 18 months. A multinomial logistic regression analysis revealed that the experience of neglect in childhood and having experienced rape at any life stage were associated with less time in treatment. Higher educational attainment and being male were associated with staying in treatment for longer periods of time. These factors may be important for identifying those at risk of terminating treatment prematurely. It is hoped that a better understanding of the factors that predict time spent in treatment will help to improve treatment outcomes for individuals who are at risk of dropping out of treatment at an early stage.

  13. Time well spent? Assessing nursing-supply chain activities.

    Science.gov (United States)

    Ferenc, Jeff

    2010-02-01

    The amount of time nurses spend providing direct patient care seems to be continually eroding. So it's little wonder a survey conducted last year of critical care, OR nurses and nurse executives found that half of the 1600 respondents feel they spend too much time on supply chain duties. Most also said their supply chain duties impact patient safe ty and their ability to provide bedside care. Experts interviewed for this report believe it's time for supply chain leaders and nurses to develop a closer working partnership. Included are their recommendations to improve performance.

  14. Modelling travel time perception in transport mode choices

    NARCIS (Netherlands)

    Varotto, S.F.; Glerum, A.; Stathopoulos, A.; Bierlaire, M.; Longo, G.

    2015-01-01

    Travel behaviour models typically rely on data afflicted by errors, in perception (e.g., over/under-estimation by traveller) and measurement (e.g., software or researcher imputation error). Such errors are shown to have a relevant impact on model outputs. So far a comprehensive framework to deal

  15. Preferences for travel time variability – A study of Danish car drivers

    DEFF Research Database (Denmark)

    Hjorth, Katrine; Rich, Jeppe

    Travel time variability (TTV) is a measure of the extent of unpredictability in travel times. It is generally accepted that TTV has a negative effect on travellers’ wellbeing and overall utility of travelling, and valuation of variability is an important issue in transport demand modelling...... preferences, to exclude non-traders, and to avoid complicated issues related to scheduled public transport services. The survey uses customised Internet questionnaires, containing a series of questions related to the traveller’s most recent morning trip to work, e.g.: • Travel time experienced on this day......, • Number of stops along the way, their duration, and whether these stops involved restrictions on time of day, • Restrictions regarding departure time from home or arrival time at work, • How often such a trip was made within the last month and the range of experienced travel times, • What the traveller...

  16. Space-time accessibility under conditions of uncertain travel times: theory and numerical simulations

    NARCIS (Netherlands)

    Ettema, D.F.; Timmermans, H.J.P.

    2007-01-01

    Recently, several accessibility measures using the space–time prism concept have been suggested in the literature. These measures fail to take into account (i) the ability of individuals to adjust their activity–travel patterns in coping with constrained choice sets, (ii) uncertainty in the

  17. A queueing framework for routing problems with time-dependent travel times

    NARCIS (Netherlands)

    Woensel, van T.; Kerbache, L.; Peremans, H.; Vandaele, N.J.

    2007-01-01

    Assigning and scheduling vehicle routes in a dynamic environment is a crucial management problem. Despite numerous publications dealing with efficient scheduling methods for vehicle routing, very few addressed the inherent stochastic and dynamic nature of travel times. In this paper, a vehicle

  18. A Micro-simulation model of updating expected travel time in provision of travel information : A bayesian belief approach implemented in a multi-state supernetwork

    NARCIS (Netherlands)

    Parvaneh, Z.; Liao, F.; Arentze, T.A.; Timmermans, H.J.P.; Shakshuki, Elhadi; Yasar, Ansar

    2014-01-01

    This study introduces a model of individual belief updating of subjective travel times as a function of the provision of different types of travel information. Travel information includes real-time prescriptive or descriptive, and public or personal information. The model is embedded in a

  19. A study on the frequency of participation and time spent on sport in different organisational settings

    NARCIS (Netherlands)

    Borgers, J.; Breedveld, K.; Tienen-Raaphorst, A.; Thibaut, E.; Vandermeerschen, H.; Vos, S.B.; Scheerder, J.

    2016-01-01

    Research question: As a result of the expansion of opportunities for leisure-time sport participation (LTSP), the question arises if differing organisational settings relate to differences in participation behaviour. This paper compares participation frequency and time spent on sport between

  20. The impact of travel distance, travel time and waiting time on health-related quality of life of diabetes patients: An investigation in six European countries.

    Science.gov (United States)

    Konerding, Uwe; Bowen, Tom; Elkhuizen, Sylvia G; Faubel, Raquel; Forte, Paul; Karampli, Eleftheria; Mahdavi, Mahdi; Malmström, Tomi; Pavi, Elpida; Torkki, Paulus

    2017-04-01

    The effects of travel distance and travel time to the primary diabetes care provider and waiting time in the practice on health-related quality of life (HRQoL) of patients with type 2 diabetes are investigated. Survey data of 1313 persons with type 2 diabetes from six regions in England (274), Finland (163), Germany (254), Greece (165), the Netherlands (354), and Spain (103) were analyzed. Various multiple linear regression analyses with four different EQ-5D-3L indices (English, German, Dutch and Spanish index) as target variables, with travel distance, travel time, and waiting time in the practice as focal predictors and with control for study region, patient's gender, patient's age, patient's education, time since diagnosis, thoroughness of provider-patient communication were computed. Interactions of regions with the remaining five control variables and the three focal predictors were also tested. There are no interactions of regions with control variables or focal predictors. The indices decrease with increasing travel time to the provider and increasing waiting time in the provider's practice. HRQoL of patients with type 2 diabetes might be improved by decreasing travel time to the provider and waiting time in the provider's practice. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Application of travel time information for traffic management : technical summary.

    Science.gov (United States)

    2012-01-01

    Using conventional methods, it is extremely costly to measure detailed traffic characteristics in high quality spatial or temporal resolution. For analyzing travel characteristics on roadways, the floating car method, developed in the 1920s, has hist...

  2. Time spent in sedentary activities in a pediatric population in Pretoria Central, South Africa.

    Science.gov (United States)

    Goon, Daniel T; Nsibambi, Constance A; Chebet, Milton

    2016-12-01

    Scant information exist on screen time behavior of South Africa children and whether they do not meet the recommendation of American Association of Pediatrics (AAP) concerning screen time activity for children is only speculative. Therefore, the purpose of this study was to examine the time spent in sedentary activities, especially screen time of South African children with regard to gender. This cross-sectional study involved a random sample of 1136 school children (548 boys; 588 girls) aged 9-13 years attending public schools in Central Pretoria, South Africa. Questionnaire was used to collect data on the participants' sedentary behaviors. The prevalence estimates for sedentary time activity was based on the guidelines (i.e., <2 or ≥2 hours per day) of AAP. The mean age of the children was 11.1±1.4 years. Sedentary activity data were collected from 548 boys (48.2%) and 588 (51.8%) girls. The majority of children spent more than two hours per day (exceeding the AAP recommendation for sedentary activity) watching TV (3.0%), worked or played on the computer (25.4%), read (1.0%), played music (27.9%), played board games (14.7%), washing clothes (8.0%), floor sweeping (10.5%), art work (18.2%), and spent time on other unspecified activities (28.6%). Boys spent more time (2 hours, 3-4 hours) watching TV (38.3%; P=0.001), playing computer (31.8 %; P=0.024) and board games (17.4%; P=0.012) than girls. The corresponding figures for girls were 35.7%, 19.2% and 12.5% for TV, computer and board games, respectively. However, the proportion of those who spent more time playing music was higher among girls (32.7%) than boys (22.4%) (P=0.002). Overall, the time spent exceeding AAP recommendation (≥ 2 hours) was not statistically (P=0.427) different between boys and girls. The time spent in sedentary activities, particularly in screen time activity among urban primary school children in Pretoria Central is excessively higher than the recommendation (i.e., ≥2 hours per day

  3. Iterative Bayesian Estimation of Travel Times on Urban Arterials: Fusing Loop Detector and Probe Vehicle Data.

    Science.gov (United States)

    Liu, Kai; Cui, Meng-Ying; Cao, Peng; Wang, Jiang-Bo

    2016-01-01

    On urban arterials, travel time estimation is challenging especially from various data sources. Typically, fusing loop detector data and probe vehicle data to estimate travel time is a troublesome issue while considering the data issue of uncertain, imprecise and even conflicting. In this paper, we propose an improved data fusing methodology for link travel time estimation. Link travel times are simultaneously pre-estimated using loop detector data and probe vehicle data, based on which Bayesian fusion is then applied to fuse the estimated travel times. Next, Iterative Bayesian estimation is proposed to improve Bayesian fusion by incorporating two strategies: 1) substitution strategy which replaces the lower accurate travel time estimation from one sensor with the current fused travel time; and 2) specially-designed conditions for convergence which restrict the estimated travel time in a reasonable range. The estimation results show that, the proposed method outperforms probe vehicle data based method, loop detector based method and single Bayesian fusion, and the mean absolute percentage error is reduced to 4.8%. Additionally, iterative Bayesian estimation performs better for lighter traffic flows when the variability of travel time is practically higher than other periods.

  4. Recent developments in guided wave travel time tomography

    Energy Technology Data Exchange (ETDEWEB)

    Zon, Tim van; Volker, Arno [TNO, Stieltjesweg 1, P.O. box 155 2600 AD Delft (Netherlands)

    2014-02-18

    The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation is an interesting addition to the current method of periodic inspections. Guided wave tomography had been developed to create a map of the wall thickness using the travel times of guided waves. It can be used for both monitoring and for inspection of pipe-segments that are difficult to access, for instance at the location of pipe-supports. An important outcome of the tomography is the minimum remaining wall thickness, as this is critical in the scheduling of a replacement of the pipe-segment. In order to improve the sizing accuracy we have improved the tomography scheme. A number of major improvements have been realized allowing to extend the application envelope to pipes with a larger wall thickness and to larger distances between the transducer rings. Simulation results indicate that the sizing accuracy has improved and that is now possible to have a spacing of 8 meter between the source-ring and the receiver-ring. Additionally a reduction of the number of sensors required might be possible as well.

  5. Experimental Results of Guided Wave Travel Time Tomography

    Science.gov (United States)

    Volker, Arno; Mast, Arjan; Bloom, Joost

    2010-02-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Both economical and social requirements are pushing the industry to even higher levels of availability, reliability and safety of installations. The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation is an interesting addition to the current method of periodic inspections reducing uncertainty and extending inspection intervals. Guided wave travel time tomography is a promising method to monitor the wall thickness quantitatively over large areas. Obviously the robustness and reliability of such a monitoring system is of paramount importance. Laboratory experiments have been carried out on a 10″ pipe with a nominal wall thickness of 8 mm. Multiple, inline defects have been created with a realistic morphology. The depth of the defects was increased stepwise from 0.5 mm to 2 mm. Additionally the influences of the presence of liquid inside the pipe and surface roughness have been evaluated as well. Experimental results show that this method is capable of providing quantitative wall thickness information over a distance of 4 meter, with a sufficient accuracy such that results can be used for trending. The method has no problems imaging multiple defects.

  6. The independent relationship between trouble controlling Facebook use, time spent on the site and distress.

    Science.gov (United States)

    Muench, Fredrick; Hayes, Marie; Kuerbis, Alexis; Shao, Sijing

    2015-09-01

    There is an emerging literature base on the relationship between maladaptive traits and "addiction" to social networking sites. These studies have operationalized addiction as either spending excessive amounts of time on social networking sites (SNS) or trouble controlling SNS use, but have not assessed the unique contribution of each of these constructs on outcomes in the same models. Moreover, these studies have exclusively been conducted with younger people rather than a heterogeneous sample. This study examined the independent relationship of a brief Facebook addiction scale, time spent on Facebook, and Facebook checking on positive and negative social domains, while controlling for self-esteem and social desirability. Participants were recruited using e-mail, SNS posts and through Amazon's MTurk system. The sample included 489 respondents ages from 18 to approximately 70, who completed a 10-15 minute survey. Results indicate that neither time spent on Facebook nor Facebook checking was significantly associated with either self-esteem, fear of negative social evaluation or social comparison, while SNS addiction symptoms were each independently associated with Facebook usage. Neither time spent on Facebook nor SNS addiction symptoms were associated with positive social relationships. Overall results suggest that time on SNS and trouble controlling use should be considered independent constructs and that interventions should target underlying loss of control as the primary intervention target above ego syntonic time spent on the site.

  7. The independent relationship between trouble controlling Facebook use, time spent on the site and distress

    Science.gov (United States)

    Muench, Fredrick; Hayes, Marie; Kuerbis, Alexis; Shao, Sijing

    2015-01-01

    Background and Aims There is an emerging literature base on the relationship between maladaptive traits and “addiction” to social networking sites. These studies have operationalized addiction as either spending excessive amounts of time on social networking sites (SNS) or trouble controlling SNS use, but have not assessed the unique contribution of each of these constructs on outcomes in the same models. Moreover, these studies have exclusively been conducted with younger people rather than a heterogeneous sample. This study examined the independent relationship of a brief Facebook addiction scale, time spent on Facebook, and Facebook checking on positive and negative social domains, while controlling for self-esteem and social desirability. Methods Participants were recruited using e-mail, SNS posts and through Amazon’s MTurk system. The sample included 489 respondents ages from 18 to approximately 70, who completed a 10–15 minute survey. Results Results indicate that neither time spent on Facebook nor Facebook checking was significantly associated with either self-esteem, fear of negative social evaluation or social comparison, while SNS addiction symptoms were each independently associated with Facebook usage. Neither time spent on Facebook nor SNS addiction symptoms were associated with positive social relationships. Discussion Overall results suggest that time on SNS and trouble controlling use should be considered independent constructs and that interventions should target underlying loss of control as the primary intervention target above ego syntonic time spent on the site. PMID:26551906

  8. Numerical modeling for saturated-zone groundwater travel time analysis at Yucca Mountain

    International Nuclear Information System (INIS)

    Arnold, B.W.; Barr, G.E.

    1996-01-01

    A three-dimensional, site-scale numerical model of groundwater flow in the saturated zone at Yucca Mountain was constructed and linked to particle tracking simulations to produce an estimate of the distribution of groundwater travel times from the potential repository to the boundary of the accessible environment. This effort and associated modeling of groundwater travel times in the unsaturated zone were undertaken to aid in the evaluation of compliance of the site with 10CFR960. These regulations stipulate that pre-waste-emplacement groundwater travel time to the accessible environment shall exceed 1,000 years along any path of likely and significant radionuclide travel

  9. The effect of a new intercity expressway based on travel time reliability using electronic toll collection data

    OpenAIRE

    Yamazaki, H.; Uno, N.; Kurauchi, F.

    2012-01-01

    This study describes a method of evaluating the level of service of road networks, based on the average travel time and travel time reliability using electronic toll collection (ETC) data. The authors focused on the variance in travel time under normal circumstances, thus, traffic accidents were removed from the database, and any effect of individual vehicle preference was excluded. They evaluated the travel time distribution based on the average travel time from ETC data for each 15-min inte...

  10. Parent Perceptions of Time Spent Meaningfully by Young Adults with Pervasive Support Needs

    Science.gov (United States)

    Rossetti, Zachary; Lehr, Donna; Lederer, Leslie; Pelerin, Dana; Huang, Shuoxi

    2015-01-01

    This article describes a qualitative study that examined how 23 young adults with pervasive support needs and limited functional communication spent their time and how their parents (n = 23) and direct support professionals (DSPs; n = 2) defined meaningfulness in relation to the young adults' experiences. Data were collected through…

  11. Evaluation of daily time spent in transportation and traffic-influenced microenvironments by urban Canadians.

    Science.gov (United States)

    Matz, Carlyn J; Stieb, David M; Egyed, Marika; Brion, Orly; Johnson, Markey

    2018-01-01

    Exposure to traffic and traffic-related air pollution is associated with a wide array of health effects. Time spent in a vehicle, in active transportation, along roadsides, and in close proximity to traffic can substantially contribute to daily exposure to air pollutants. For this study, we evaluated daily time spent in transportation and traffic-influenced microenvironments by urban Canadians using the Canadian Human Activity Pattern Survey (CHAPS) 2 results. Approximately 4-7% of daily time was spent in on- or near-road locations, mainly associated with being in a vehicle and smaller contributions from active transportation. Indoor microenvironments can be impacted by traffic emissions, especially when located near major roadways. Over 60% of the target population reported living within one block of a roadway with moderate to heavy traffic, which was variable with income level and city, and confirmed based on elevated NO 2 exposure estimated using land use regression. Furthermore, over 55% of the target population ≤ 18 years reported attending a school or daycare in close proximity to moderate to heavy traffic, and little variation was observed based on income or city. The results underline the importance of traffic emissions as a major source of exposure in Canadian urban centers, given the time spent in traffic-influenced microenvironments.

  12. The Relationship between Motivation, Learning Approaches, Academic Performance and Time Spent

    Science.gov (United States)

    Everaert, Patricia; Opdecam, Evelien; Maussen, Sophie

    2017-01-01

    Previous literature calls for further investigation in terms of precedents and consequences of learning approaches (deep learning and surface learning). Motivation as precedent and time spent and academic performance as consequences are addressed in this paper. The study is administered in a first-year undergraduate course. Results show that the…

  13. Associations between Parental and Friend Social Support and Children's Physical Activity and Time Spent outside Playing.

    Science.gov (United States)

    Loucaides, Constantinos A; Tsangaridou, Niki

    2017-01-01

    The purpose of this study was to examine the structural validity of a parent and a child questionnaire that assessed parental and friends' influences on children's physical activity and investigate the associations between the derived factors, physical activity, and time spent outside. Children ( N = 154, mean age = 11.7) and 144 of their parents completed questionnaires assessing parental and friends' influences on children's physical activity. Children wore a pedometer for six days. Exploratory factor analyses revealed four factors for the parental and five for the child's questionnaire that explained 66.71% and 63.85% of the variance, respectively. Five factors were significantly associated with physical activity and five significantly associated with time spent outside. Higher correlations were revealed between "general friend support," "friends' activity norms," and physical activity ( r = 0.343 and 0.333 resp., p friend support" and time spent outside ( r = 0.460, p parental and friends' influences on physical activity from both parents and children may provide a more complete picture of influences. Parents and friends seem to influence children's physical activity behavior and time spent outside, but friends' influences may have a stronger impact on children's behaviors.

  14. Re-Examining Gender Differences in Video Game Play: Time Spent and Feelings of Success

    Science.gov (United States)

    Hamlen, Karla R.

    2010-01-01

    Research has shown that, among children, boys tend to play video games more than girls do. There are several theories addressing this phenomenon, including that stereotypes and lack of opportunity leave girls feeling inadequate with certain types of technology. No research has yet examined the interactive relationships between time spent playing…

  15. Time travel and warp drives a scientific guide to shortcuts through time and space

    CERN Document Server

    Everett, Allen

    2012-01-01

    Sci-fi makes it look so easy. Receive a distress call from Alpha Centauri? No problem: punch the warp drive and you're there in minutes. Facing a catastrophe that can't be averted? Just pop back in the timestream and stop it before it starts. But for those of us not lucky enough to live in a science-fictional universe, are these ideas merely flights of fancy—or could it really be possible to travel through time or take shortcuts between stars?Cutting-edge physics may not be able to answer those questions yet, but it does offer up some tantalizing possibilities. In Time Travel and W

  16. Approaching the Brachistochrone Using Inclined Planes--Striving for Shortest or Equal Travelling Times

    Science.gov (United States)

    Theilmann, Florian

    2017-01-01

    The classical "brachistochrone" problem asks for the path on which a mobile point M just driven by its own gravity will travel in the shortest possible time between two given points "A" and "B." The resulting curve, the cycloid, will also be the "tautochrone" curve, i.e. the travelling time of the mobile…

  17. Travelling Solitary Wave Solutions for Generalized Time-delayed Burgers-Fisher Equation

    International Nuclear Information System (INIS)

    Deng Xijun; Han Libo; Li Xi

    2009-01-01

    In this paper, travelling wave solutions for the generalized time-delayed Burgers-Fisher equation are studied. By using the first-integral method, which is based on the ring theory of commutative algebra, we obtain a class of travelling solitary wave solutions for the generalized time-delayed Burgers-Fisher equation. A minor error in the previous article is clarified. (general)

  18. Mental time travel : A conceptual overview of social psychological perspectives on a fundamental human capacity

    NARCIS (Netherlands)

    Epstude, K.; Peetz, J.

    Humans have the unique capacity to mentally travel through time, that is, to reflect on the past, anticipate the future, and construct alternate realities in their minds. The ability to mentally travel through time affects a variety of social psychological topics. Representations of events can

  19. Self-Efficacy Beliefs and Mental Time Travel Ability: Uncovering a Hidden Relationship in Educational Settings

    Science.gov (United States)

    Eren, Altay

    2009-01-01

    The aim of this study was threefold: first, it was to explore the profiles of student teachers' mental time travel ability; second, it was to examine the relationship between student teachers' mental time travel ability and self-efficacy beliefs; and third, it was to investigate the role of self-efficacy beliefs in relationship between the past…

  20. Does Involuntary Mental Time Travel Make Sense in Prospective Teachers' Feelings and Behaviors during Lessons?

    Science.gov (United States)

    Eren, Altay; Yesilbursa, Amanda

    2013-01-01

    This study examined the effects of involuntary mental time travel into the past and into the future on prospective teachers' feelings and behaviors during the period of a class hour. A total of 110 prospective teachers participated voluntarily in the study. The results of the present study showed that (a) the involuntary mental time travel into…

  1. METHOD OF ESTIMATING THE TRAVEL TIME OF NONINTERACTING SOLUTES THROUGH COMPACTED SOIL MATERIAL

    Science.gov (United States)

    The pollutant travel time through compacted soil material (i.e., when a pollutant introduced at the top first appears at the bottom) cannot be accurately predicted from the permeability (saturated hydraulic conductivity) alone. The travel time is also dependent on the effective p...

  2. A Simplified Network Model for Travel Time Reliability Analysis in a Road Network

    Directory of Open Access Journals (Sweden)

    Kenetsu Uchida

    2017-01-01

    Full Text Available This paper proposes a simplified network model which analyzes travel time reliability in a road network. A risk-averse driver is assumed in the simplified model. The risk-averse driver chooses a path by taking into account both a path travel time variance and a mean path travel time. The uncertainty addressed in this model is that of traffic flows (i.e., stochastic demand flows. In the simplified network model, the path travel time variance is not calculated by considering all travel time covariance between two links in the network. The path travel time variance is calculated by considering all travel time covariance between two adjacent links in the network. Numerical experiments are carried out to illustrate the applicability and validity of the proposed model. The experiments introduce the path choice behavior of a risk-neutral driver and several types of risk-averse drivers. It is shown that the mean link flows calculated by introducing the risk-neutral driver differ as a whole from those calculated by introducing several types of risk-averse drivers. It is also shown that the mean link flows calculated by the simplified network model are almost the same as the flows calculated by using the exact path travel time variance.

  3. Making Decisions with the Future in Mind: Developmental and Comparative Identification of Mental Time Travel

    Science.gov (United States)

    Suddendorf, T.; Busby, J.

    2005-01-01

    Mechanisms that produce behavior which increase future survival chances provide an adaptive advantage. The flexibility of human behavior is at least partly the result of one such mechanism, our ability to travel mentally in time and entertain potential future scenarios. We can study mental time travel in children using language. Current results…

  4. Complexity in the validation of ground-water travel time in fractured flow and transport systems

    International Nuclear Information System (INIS)

    Davies, P.B; Hunter, R.L.; Pickens, J.F.

    1991-02-01

    Ground-water travel time is a widely used concept in site assessment for radioactive waste disposal. While ground-water travel time was originally conceived to provide a simple performance measure for evaluating repository sites, its definition in many flow and transport environments is ambiguous. The US Department of Energy siting guidelines (10 CFR 960) define ground-water travel time as the time required for a unit volume of water to travel between two locations, calculated by dividing travel-path length by the quotient of average ground-water flux and effective porosity. Defining a meaningful effective porosity in a fractured porous material is a significant problem. Although the Waste Isolation Pilot Plant (WIPP) is not subject to specific requirements for ground-water travel time, travel times have been computed under a variety of model assumptions. Recently completed model analyses for WIPP illustrate the difficulties in applying a ground-water travel-time performance measure to flow and transport in fractured, fully saturated flow systems. 12 refs., 4 figs

  5. Complexity in the validation of ground-water travel time in fractured flow and transport systems

    International Nuclear Information System (INIS)

    Davies, P.B.; Hunter, R.L.; Pickens, J.F.

    1991-01-01

    Ground-water travel time is a widely used concept in site assessment for radioactive waste disposal. While ground-water travel time was originally conceived to provide a simple performance measure for evaluating repository sites, its definition in many flow and transport environments is ambiguous. The U.S. Department of Energy siting guidelines (10 CFR 960) define ground-water travel time as the time required for a unit volume of water to travel between two locations, calculated by dividing travel-path length by the quotient of average ground-water flux and effective porosity. Defining a meaningful effective porosity in a fractured porous material is a significant problem. Although the Waste Isolation Pilot Plant (WIPP) is not subject to specific requirements for ground-water travel time, travel times have been computed under a variety of model assumptions. Recently completed model analyses for WIPP illustrate the difficulties in applying a ground-water travel-time performance measure to flow and transport in fractured, fully saturated flow systems. Computer code used: SWIFT II (flow and transport code). 4 figs., 12 refs

  6. Improving The Accuracy Of Bluetooth Based Travel Time Estimation Using Low-Level Sensor Data

    DEFF Research Database (Denmark)

    Araghi, Bahar Namaki; Tørholm Christensen, Lars; Krishnan, Rajesh

    2013-01-01

    triggered by a single device. This could lead to location ambiguity and reduced accuracy of travel time estimation. Therefore, the accuracy of travel time estimations by Bluetooth Technology (BT) depends upon how location ambiguity is handled by the estimation method. The issue of multiple detection events...... in the context of travel time estimation by BT has been considered by various researchers. However, treatment of this issue has remained simplistic so far. Most previous studies simply used the first detection event (Enter-Enter) as the best estimate. No systematic analysis for exploring the most accurate method...... of estimating travel time using multiple detection events has been conducted. In this study different aspects of BT detection zone, including size and its impact on the accuracy of travel time estimation, are discussed. Moreover, four alternative methods are applied; namely, Enter-Enter, Leave-Leave, Peak...

  7. Evaluation Of Groundwater Pathways And Travel Times From The Nevada Test Site To The Potential Yucca Mountain Repository

    International Nuclear Information System (INIS)

    K.F. Pohlman; J. Zhu; M. Ye; J. Chapman; C. Russell; D.S. Shafer

    2006-01-01

    Yucca Mountain (YM), Nevada, has been recommended as a deep geological repository for the disposal of spent fuel and high-level radioactive waste. If YM is licensed as a repository by the Nuclear Regulatory Commission, it will be important to identify the potential for radionuclides to migrate from underground nuclear testing areas located on the Nevada Test Site (NTS) to the hydraulically downgradient repository area to ensure that monitoring does not incorrectly attribute repository failure to radionuclides originating from other sources. In this study, we use the Death Valley Regional Flow System (DVRFS) model developed by the U.S. Geological Survey to investigate potential groundwater migration pathways and associated travel times from the NTS to the proposed YM repository area. Using results from the calibrated DVRFS model and the particle tracking post-processing package MODPATH, we modeled three-dimensional groundwater advective pathways in the NTS and YM region. Our study focuses on evaluating the potential for groundwater pathways between the NTS and YM withdrawal area and whether travel times for advective flow along these pathways coincide with the prospective monitoring timeframe at the proposed repository. We include uncertainty in effective porosity, as this is a critical variable in the determination of time for radionuclides to travel from the NTS region to the YM withdrawal area. Uncertainty in porosity is quantified through evaluation of existing site data and expert judgment and is incorporated in the model through Monte Carlo simulation. Since porosity information is limited for this region, the uncertainty is quite large and this is reflected in the results as a large range in simulated groundwater travel times

  8. The impact of travel time on geographic distribution of dialysis patients.

    Science.gov (United States)

    Kashima, Saori; Matsumoto, Masatoshi; Ogawa, Takahiko; Eboshida, Akira; Takeuchi, Keisuke

    2012-01-01

    The geographic disparity of prevalence rates among dialysis patients is unclear. We evaluate the association between travel time to dialysis facilities and prevalence rates of dialysis patients living in 1,867 census areas of Hiroshima, Japan. Furthermore, we study the effects of geographic features (mainland or island) on the prevalence rates and assess if these effects modify the association between travel time and prevalence. The study subjects were all 7,374 people that were certified as the "renal disabled" by local governments in 2011. The travel time from each patient to the nearest available dialysis facility was calculated by incorporating both travel time and the capacity of all 98 facilities. The effect of travel time on the age- and sex-adjusted standard prevalence rate (SPR) and 95% confidence intervals (CIs) at each census area was evaluated in two-level Poisson regression models with 1,867 census areas (level 1) nested within 35 towns or cities (level 2). The results were adjusted for area-based parameters of socioeconomic status, urbanity, and land type. Furthermore, the SPR of dialysis patients was calculated in each specific subgroup of population for travel time, land type, and combination of land type and travel time. In the regression analysis, SPR decreased by 5.2% (95% CI: -7.9--2.3) per 10-min increase in travel time even after adjusting for potential confounders. The effect of travel time on prevalence was different in the mainland and island groups. There was no travel time-dependent SPR disparity on the islands. The SPR among remote residents (>30 min from facilities) in the mainland was lower (0.77, 95% CI: 0.71-0.85) than that of closer residents (≤ 30 min; 0.95, 95% CI: 0.92-0.97). The prevalence of dialysis patients was lower among remote residents. Geographic difficulties for commuting seem to decrease the prevalence rate.

  9. Particle tracking for unsaturated-zone groundwater travel time analysis at Yucca Mountain

    International Nuclear Information System (INIS)

    Arnold, B.W.; Skinner, L.H.; Zieman, N.B.

    1995-01-01

    A particle tracking code developed to link numerical modeling of groundwater flow in the unsaturated zone to the analysis of groundwater travel times was used to produce preliminary estimates of the distribution of groundwater-travel time from a potential repository at Yucca Mountain, Nevada to the water table. Compliance with 10CFR960 requires the demonstration that pre-waste-emplacement groundwater travel time from the disturbed zone to the accessible environment is expected to exceed 1,000 years along any path of likely and significant radionuclide travel. The use of multiple particles and multiple realizations of the geology and parameter distributions in the unsaturated zone allows a probabilistic analysis of groundwater travel times that may be applied for evaluating compliance

  10. Highway travel time information system based on cumulative count curves and new tracking technologies

    Energy Technology Data Exchange (ETDEWEB)

    Soriguera Marti, F.; Martinez-Diaz, M.; Perez Perez, I.

    2016-07-01

    Travel time is probably the most important indicator of the level of service of a highway, and it is also the most appreciated information for its users. Administrations and private companies make increasing efforts to improve its real time estimation. The appearance of new technologies makes the precise measurement of travel times easier than never before. However, direct measurements of travel time are, by nature, outdated in real time, and lack of the desired forecasting capabilities. This paper introduces a new methodology to improve the real time estimation of travel times by using the equipment usually present in most highways, i.e., loop detectors, in combination with Automatic Vehicle Identification or Tracking Technologies. One of the most important features of the method is the usage of cumulative counts at detectors as an input, avoiding the drawbacks of common spot-speed methodologies. Cumulative count curves have great potential for freeway travel time information systems, as they provide spatial measurements and thus allow the calculation of instantaneous travel times. In addition, they exhibit predictive capabilities. Nevertheless, they have not been used extensively mainly because of the error introduced by the accumulation of the detector drift. The proposed methodology solves this problem by correcting the deviations using direct travel time measurements. The method results highly beneficial for its accuracy as well as for its low implementation cost. (Author)

  11. Prospective and retrospective time perception are related to mental time travel: evidence from Alzheimer's disease.

    Science.gov (United States)

    El Haj, Mohamad; Moroni, Christine; Samson, Séverine; Fasotti, Luciano; Allain, Philippe

    2013-10-01

    Unlike prospective time perception paradigms, in which participants are aware that they have to estimate forthcoming time, little is known about retrospective time perception in normal aging and Alzheimer's disease (AD). Our paper addresses this shortcoming by comparing prospective and retrospective time estimation in younger adults, older adults, and AD patients. In four prospective tasks (lasting 30s, 60s, 90s, or 120s) participants were asked to read a series of numbers and to provide a verbal estimation of the reading time. In four other retrospective tasks, they were not informed about time judgment until they were asked to provide a verbal estimation of four elapsed time intervals (lasting 30s, 60s, 90s, or 120s). AD participants gave shorter verbal time estimations than older adults and younger participants did, suggesting that time is perceived to pass quickly in these patients. For all participants, the duration of the retrospective tasks was underestimated as compared to the prospective tasks and both estimations were shorter than the real time interval. Prospective time estimation was further correlated with mental time travel, as measured with the Remember/Know paradigm. Mental time travel was even higher correlated with retrospective time estimation. Our findings shed light on the relationship between time perception and the ability to mentally project oneself into time, two skills contributing to human memory functioning. Finally, time perception deficits, as observed in AD patients, can be interpreted in terms of dramatic changes occurring in frontal lobes and hippocampus. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. Some notes on the Timing of Geological Disposal of CANDU Spent Fuels

    International Nuclear Information System (INIS)

    Choi, Heui Joo; Kook, Dong Hak; Choi, Jong Won

    2010-01-01

    CANDU spent fuel is to be disposed of at repository finally rather than recycled because of its low fissile nuclide concentration. But the difficult situation of finding a repository site can not help introducing a interim storage in the short term. It is required to find an optimum timing of geological disposal of CANDU spent fuels related to the interim storage operation period. The major factors for determining the disposal starting time are considered as safety, economics, and public acceptance. Safety factor is compared in terms of the decay heat and non-proliferation. Economics factor is compared from the point of the operation cost, and public acceptance factor is reviewed from the point of retrievability and inter-generation ethics. This paper recommended the best solution for the disposal starting time by analyzing the above factors. It is concluded that the optimum timing for the CANDU spent fuel disposal is around 2041 and that the sooner disposal time, the better from the point of technical and safety aspects.

  13. Value of travel-time reliability : commuters' route-choice behavior in the Twin Cities.

    Science.gov (United States)

    2011-10-01

    Travel-time variability is a noteworthy factor in network performance. It measures the temporal uncertainty experienced by users in their : movement between any two nodes in a network. The importance of the time variance depends on the penalties incu...

  14. Improving value of travel time savings estimation for more effective transportation project evaluation.

    Science.gov (United States)

    2012-12-01

    Estimates of value of time (VOT) and value of travel time savings (VTTS) are critical elements in benefitcost : analyses of transportation projects and in developing congestion pricing policies. In addition, : differences in VTTS among various modes ...

  15. Short-term adaptations as a response to travel time: results of a stated adaptation experimentincreases

    NARCIS (Netherlands)

    Psarra, I.; Arentze, T.A.; Timmermans, H.J.P.

    2016-01-01

    This study focused on short-term dynamics of activity-travel behavior as a response to travel time increases. It is assumed that short-term changes are triggered by stress, which is defined as the deviation between an individual’s aspirations and his or her daily experiences. When stress exceeds a

  16. Perceptions of public transport travel time and their effect on choice-sets among car drivers

    NARCIS (Netherlands)

    N.J.A. van Exel (Job); P. Rietveld (Piet)

    2010-01-01

    textabstractCar drivers' perceptions of the quality of alternative travel modes have been identified as a barrier for including these alternatives in their choice sets. The present study investigated the accuracy of car drivers' perceptions of public transport (PT) travel time and the potential

  17. Behavioural decisions of travel-time ratios for work, maintenance and leisure activities in the Netherlands.

    NARCIS (Netherlands)

    Susilo, Y.S.; Dijst, M.J.

    2010-01-01

    Using the 2005 Dutch National Travel Survey data-set this paper investigates the influences of socio-demographics, journey patterns and built environment factors on the ratio of travel time and activity duration that an individual spends when engaging in work, daily shopping, non-daily shopping

  18. Bus Travel Time Deviation Analysis Using Automatic Vehicle Location Data and Structural Equation Modeling

    Directory of Open Access Journals (Sweden)

    Xiaolin Gong

    2015-01-01

    Full Text Available To investigate the influences of causes of unreliability and bus schedule recovery phenomenon on microscopic segment-level travel time variance, this study adopts Structural Equation Modeling (SEM to specify, estimate, and measure the theoretical proposed models. The SEM model establishes and verifies hypotheses for interrelationships among travel time deviations, departure delays, segment lengths, dwell times, and number of traffic signals and access connections. The finally accepted model demonstrates excellent fitness. Most of the hypotheses are supported by the sample dataset from bus Automatic Vehicle Location system. The SEM model confirms the bus schedule recovery phenomenon. The departure delays at bus terminals and upstream travel time deviations indeed have negative impacts on travel time fluctuation of buses en route. Meanwhile, the segment length directly and negatively impacts travel time variability and inversely positively contributes to the schedule recovery process; this exogenous variable also indirectly and positively influences travel times through the existence of signalized intersections and access connections. This study offers a rational approach to analyzing travel time deviation feature. The SEM model structure and estimation results facilitate the understanding of bus service performance characteristics and provide several implications for bus service planning, management, and operation.

  19. Parsimonious wave-equation travel-time inversion for refraction waves

    KAUST Repository

    Fu, Lei

    2017-02-14

    We present a parsimonious wave-equation travel-time inversion technique for refraction waves. A dense virtual refraction dataset can be generated from just two reciprocal shot gathers for the sources at the endpoints of the survey line, with N geophones evenly deployed along the line. These two reciprocal shots contain approximately 2N refraction travel times, which can be spawned into O(N2) refraction travel times by an interferometric transformation. Then, these virtual refraction travel times are used with a source wavelet to create N virtual refraction shot gathers, which are the input data for wave-equation travel-time inversion. Numerical results show that the parsimonious wave-equation travel-time tomogram has about the same accuracy as the tomogram computed by standard wave-equation travel-time inversion. The most significant benefit is that a reciprocal survey is far less time consuming than the standard refraction survey where a source is excited at each geophone location.

  20. Valuing long-haul and metropolitan freight travel time and reliability

    Science.gov (United States)

    2000-12-01

    Most evaluations and economic assessments of transportation proposal and policies in Australia omit a valuation of time spent in transit for individual items or loads of freight. Knowledge of delays and the practical value of reliability can be usefu...

  1. Commuting to work: RN travel time to employment in rural and urban areas.

    Science.gov (United States)

    Rosenberg, Marie-Claire; Corcoran, Sean P; Kovner, Christine; Brewer, Carol

    2011-02-01

    To investigate the variation in average daily travel time to work among registered nurses (RNs) living in urban, suburban, and rural areas. We examine how travel time varies across RN characteristics, job setting, and availability of local employment opportunities. Descriptive statistics and linear regression using a 5% sample from the 2000 Census and a longitudinal survey of newly licensed RNs (NLRN). Travel time for NLRN respondents was estimated using geographic information systems (GIS) software. In the NLRN, rural nurses and those living in small towns had significantly longer average commute times. Young married RNs and RNs with children also tended to have longer commute times, as did RNs employed by hospitals. The findings indicate that travel time to work varies significantly across locale types. Further research is needed to understand whether and to what extent lengthy commute times impact RN workforce needs in rural and urban areas.

  2. Impact of connected vehicle guidance information on network-wide average travel time

    Directory of Open Access Journals (Sweden)

    Jiangfeng Wang

    2016-12-01

    Full Text Available With the emergence of connected vehicle technologies, the potential positive impact of connected vehicle guidance on mobility has become a research hotspot by data exchange among vehicles, infrastructure, and mobile devices. This study is focused on micro-modeling and quantitatively evaluating the impact of connected vehicle guidance on network-wide travel time by introducing various affecting factors. To evaluate the benefits of connected vehicle guidance, a simulation architecture based on one engine is proposed representing the connected vehicle–enabled virtual world, and connected vehicle route guidance scenario is established through the development of communication agent and intelligent transportation systems agents using connected vehicle application programming interface considering the communication properties, such as path loss and transmission power. The impact of connected vehicle guidance on network-wide travel time is analyzed by comparing with non-connected vehicle guidance in response to different market penetration rate, following rate, and congestion level. The simulation results explore that average network-wide travel time in connected vehicle guidance shows a significant reduction versus that in non–connected vehicle guidance. Average network-wide travel time in connected vehicle guidance have an increase of 42.23% comparing to that in non-connected vehicle guidance, and average travel time variability (represented by the coefficient of variance increases as the travel time increases. Other vital findings include that higher penetration rate and following rate generate bigger savings of average network-wide travel time. The savings of average network-wide travel time increase from 17% to 38% according to different congestion levels, and savings of average travel time in more serious congestion have a more obvious improvement for the same penetration rate or following rate.

  3. The influence of travel time on breast cancer characteristics, receipt of primary therapy, and surveillance mammography.

    Science.gov (United States)

    Onega, Tracy; Cook, Andrea; Kirlin, Beth; Shi, Xun; Alford-Teaster, Jennifer; Tuzzio, Leah; Buist, Diana S M

    2011-08-01

    Travel time has been shown to influence some aspects of cancer characteristics at diagnosis and care for women with breast cancer, but important gaps remain in our understanding of its impact. We examined the influence of travel time to the nearest radiology facility on breast cancer characteristics, treatment, and surveillance for women with early-stage invasive breast cancer. We included 1,012 women with invasive breast cancer (stages I and II) who had access to care within an integrated health care delivery system in western Washington State. The travel times to the nearest radiology facility were calculated for all the U.S. Census blocks within the study area and assigned to women based on residence at diagnosis. We collected cancer characteristics, primary and adjuvant therapies, and surveillance mammography for at least 2.5 years post diagnosis and used multivariable analyses to test the associations of travel time. The majority of women (68.6%) lived within 20 min of the nearest radiology facility, had stage I disease (72.7%), received breast conserving therapy (68.7%), and had annual surveillance mammography the first 2 years after treatment (73.7%). The travel time was not significantly associated with the stage or surveillance mammography after adjusting for covariates. Primary therapy was significantly related to travel time, with greater travel time (>30 min vs. ≤ 10 min) associated with a higher likelihood of mastectomy compared to breast conserving surgery (RR = 1.53; 95% CI, 1.16-2.01). The travel time was not associated with the stage at diagnosis or surveillance mammography receipt. The travel time does seem to influence the type of primary therapy among women with breast cancer, suggesting that women may prefer low frequency services, such as mastectomy, if geographic access to a radiology facility is limited.

  4. Simple Kinematic Pathway Approach (KPA) to Catchment-scale Travel Time and Water Age Distributions

    Science.gov (United States)

    Soltani, S. S.; Cvetkovic, V.; Destouni, G.

    2017-12-01

    The distribution of catchment-scale water travel times is strongly influenced by morphological dispersion and is partitioned between hillslope and larger, regional scales. We explore whether hillslope travel times are predictable using a simple semi-analytical "kinematic pathway approach" (KPA) that accounts for dispersion on two levels of morphological and macro-dispersion. The study gives new insights to shallow (hillslope) and deep (regional) groundwater travel times by comparing numerical simulations of travel time distributions, referred to as "dynamic model", with corresponding KPA computations for three different real catchment case studies in Sweden. KPA uses basic structural and hydrological data to compute transient water travel time (forward mode) and age (backward mode) distributions at the catchment outlet. Longitudinal and morphological dispersion components are reflected in KPA computations by assuming an effective Peclet number and topographically driven pathway length distributions, respectively. Numerical simulations of advective travel times are obtained by means of particle tracking using the fully-integrated flow model MIKE SHE. The comparison of computed cumulative distribution functions of travel times shows significant influence of morphological dispersion and groundwater recharge rate on the compatibility of the "kinematic pathway" and "dynamic" models. Zones of high recharge rate in "dynamic" models are associated with topographically driven groundwater flow paths to adjacent discharge zones, e.g. rivers and lakes, through relatively shallow pathway compartments. These zones exhibit more compatible behavior between "dynamic" and "kinematic pathway" models than the zones of low recharge rate. Interestingly, the travel time distributions of hillslope compartments remain almost unchanged with increasing recharge rates in the "dynamic" models. This robust "dynamic" model behavior suggests that flow path lengths and travel times in shallow

  5. Effects of travel time delay on multi-faceted activity scheduling under space-time constraints : a simulation study

    NARCIS (Netherlands)

    Rasouli, S.; Timmermans, H.J.P.

    2014-01-01

    This paper presents the results of a study, which simulates the effects of travel time delay on adaptations of planned activity-travel schedules. The activity generation and scheduling engine of the Albatross model system is applied to a fraction of the synthetic population of the Rotterdam region,

  6. Screen time and passive school travel as independent predictors of cardiorespiratory fitness in youth.

    Science.gov (United States)

    Sandercock, Gavin R H; Ogunleye, Ayodele A

    2012-05-01

    The most prevalent sedentary behaviours in children and adolescents are engagement with small screen media (screen-time) and passive travel (by motorised vehicle). The objective of this research was to assess the independence of these behaviours from one another and from physical activity as predictors of cardiorespiratory fitness in youth. We measured cardiorespiratory fitness in n=6819 10-16 year olds (53% male) who self-reported their physical activity (7-day recall) school travel and screen time habits. Travel was classified as active (walking, cycling) or passive; screen time as 4 h. The multivariate odds of being fit were higher in active travel (Boys: OR 1.32, 95% CI: 1.09-1.59; Girls: OR 1.46, 1.15-1.84) than in passive travel groups. Boys reporting low screen time were more likely to be fit than those reporting >4 h (OR 2.11, 95% CI: 1.68-2.63) as were girls (OR 1.66, 95% CI: 1.24-2.20). These odds remained significant after additionally controlling for physical activity. Passive travel and high screen time are independently associated with poor cardiorespiratory fitness in youth, and this relationship is independent of physical activity levels. A lifestyle involving high screen time and habitual passive school travel appears incompatible with healthful levels of cardiorespiratory fitness in youth. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. Time travels in archaeology. Between Hollywood films and historical re-enactment?

    Directory of Open Access Journals (Sweden)

    Dawid Kobialka

    2017-01-01

    Full Text Available One of the recently most popular ways of experiencing the past is time travelling. It is ‘an experience and social practice in the present that evokes a past (or future reality’ (Holtorf 2009: 33. In this article, I mainly discuss the political aspect of time travelling. I focus on cinema as a medium which closely links archaeology with the time travel phenomenon. Two Oscars galas, of 2010 and 2012, are scrutinised as case studies. The text is a political intervention to start dreaming dangerously, to contribute as an archaeologist to the critique of the utopia of capitalism (see also Hernando 2005: 75.

  8. Trip Travel Time Forecasting Based on Selective Forgetting Extreme Learning Machine

    Directory of Open Access Journals (Sweden)

    Zhiming Gui

    2014-01-01

    Full Text Available Travel time estimation on road networks is a valuable traffic metric. In this paper, we propose a machine learning based method for trip travel time estimation in road networks. The method uses the historical trip information extracted from taxis trace data as the training data. An optimized online sequential extreme machine, selective forgetting extreme learning machine, is adopted to make the prediction. Its selective forgetting learning ability enables the prediction algorithm to adapt to trip conditions changes well. Experimental results using real-life taxis trace data show that the forecasting model provides an effective and practical way for the travel time forecasting.

  9. Tile Drainage Density Reduces Groundwater Travel Times and Compromises Riparian Buffer Effectiveness.

    Science.gov (United States)

    Schilling, Keith E; Wolter, Calvin F; Isenhart, Thomas M; Schultz, Richard C

    2015-11-01

    Strategies to reduce nitrate-nitrogen (nitrate) pollution delivered to streams often seek to increase groundwater residence time to achieve measureable results, yet the effects of tile drainage on residence time have not been well documented. In this study, we used a geographic information system groundwater travel time model to quantify the effects of artificial subsurface drainage on groundwater travel times in the 7443-ha Bear Creek watershed in north-central Iowa. Our objectives were to evaluate how mean groundwater travel times changed with increasing drainage intensity and to assess how tile drainage density reduces groundwater contributions to riparian buffers. Results indicate that mean groundwater travel times are reduced with increasing degrees of tile drainage. Mean groundwater travel times decreased from 5.6 to 1.1 yr, with drainage densities ranging from 0.005 m (7.6 mi) to 0.04 m (62 mi), respectively. Model simulations indicate that mean travel times with tile drainage are more than 150 times faster than those that existed before settlement. With intensive drainage, less than 2% of the groundwater in the basin appears to flow through a perennial stream buffer, thereby reducing the effectiveness of this practice to reduce stream nitrate loads. Hence, strategies, such as reconnecting tile drainage to buffers, are promising because they increase groundwater residence times in tile-drained watersheds. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  10. Factors influencing modes of transport and travel time for obstetric care: a mixed methods study in Zambia and Uganda.

    Science.gov (United States)

    Sacks, Emma; Vail, Daniel; Austin-Evelyn, Katherine; Greeson, Dana; Atuyambe, Lynn M; Macwan'gi, Mubiana; Kruk, Margaret E; Grépin, Karen A

    2016-04-01

    Transportation is an important barrier to accessing obstetric care for many pregnant and postpartum women in low-resource settings, particularly in rural areas. However, little is known about how pregnant women travel to health facilities in these settings. We conducted 1633 exit surveys with women who had a recent facility delivery and 48 focus group discussions with women who had either a home or a facility birth in the past year in eight districts in Uganda and Zambia. Quantitative data were analysed using univariate statistics, and qualitative data were analysed using thematic content analysis techniques. On average, women spent 62-68 min travelling to a clinic for delivery. Very different patterns in modes of transport were observed in the two countries: 91% of Ugandan women employed motorized forms of transportation, while only 57% of women in Zambia did. Motorcycle taxis were the most commonly used in Uganda, while cars, trucks and taxis were the most commonly used mode of transportation in Zambia. Lower-income women were less likely to use motorized modes of transportation: in Zambia, women in the poorest quintile took 94 min to travel to a health facility, compared with 34 for the wealthiest quintile; this difference between quintiles was ∼50 min in Uganda. Focus group discussions confirmed that transport is a major challenge due to a number of factors we categorized as the 'three A's:' affordability, accessibility and adequacy of transport options. Women reported that all of these factors had influenced their decision not to deliver in a health facility. The two countries had markedly different patterns of transportation for obstetric care, and modes of transport and travel times varied dramatically by wealth quintile, which policymakers need to take into account when designing obstetric transport interventions. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  11. Travel Cost Inference from Sparse, Spatio-Temporally Correlated Time Series Using Markov Models

    DEFF Research Database (Denmark)

    Yang, Bin; Guo, Chenjuan; Jensen, Christian S.

    2013-01-01

    of such time series offers insight into the underlying system and enables prediction of system behavior. While the techniques presented in the paper apply more generally, we consider the case of transportation systems and aim to predict travel cost from GPS tracking data from probe vehicles. Specifically, each...... road segment has an associated travel-cost time series, which is derived from GPS data. We use spatio-temporal hidden Markov models (STHMM) to model correlations among different traffic time series. We provide algorithms that are able to learn the parameters of an STHMM while contending...... with the sparsity, spatio-temporal correlation, and heterogeneity of the time series. Using the resulting STHMM, near future travel costs in the transportation network, e.g., travel time or greenhouse gas emissions, can be inferred, enabling a variety of routing services, e.g., eco-routing. Empirical studies...

  12. Effect of Automobile Travel Time Between Patients' Homes and Ophthalmologists' Offices on Screening for Diabetic Retinopathy.

    Science.gov (United States)

    Macon, Céline; Carrier, Hélène; Janczewski, Aurélie; Verger, Pierre; Casanova, Ludovic

    2018-01-01

    The accessibility of ophthalmologists appears to influence the quality of screening for diabetic retinopathy (DR). The principal objective of this study was to analyze the effect of automobile travel time to the closest ophthalmologist on the time to DR screening. This historical cohort study used reimbursement databases from the principal national health insurance fund. Patients were included if they had been reimbursed at least thrice for oral antidiabetic medications in the 12 months before the study start date. Patients were followed up from January 1, 2008, for 4 years. The expected event was a DR screening by an ocular fundus examination. The automobile travel time to the nearest ophthalmologist was calculated by the distance between communes, estimated by appropriate software. A Kaplan-Meier curve and a multivariate Cox model were used to model the effect of travel time on the time until DR screening. A sensitivity analysis of travel time described the results of the Cox model. At the start of 2008, 6,573 patients living in 328 different municipalities were included. The multivariate model found that patients living 60 min or more away from an ophthalmologist had a lower instantaneous probability of DR screening than those living travel time. Increased automobile travel time for patients with diabetes to the nearest ophthalmologist was associated with a longer time to DR screening.

  13. Developing corridor-level truck travel time estimates and other freight performance measures from archived ITS data.

    Science.gov (United States)

    2009-08-01

    The objectives of this research were to retrospectively study the feasibility for using truck transponder data to produce freight corridor performance measures (travel times) and real-time traveler information. To support this analysis, weigh-in-moti...

  14. Evaluation of Effective Factors on Travel Time in Optimization of Bus Stops Placement Using Genetic Algorithm

    Science.gov (United States)

    Bargegol, Iraj; Ghorbanzadeh, Mahyar; Ghasedi, Meisam; Rastbod, Mohammad

    2017-10-01

    In congested cities, locating and proper designing of bus stops according to the unequal distribution of passengers is crucial issue economically and functionally, since this subject plays an important role in the use of bus system by passengers. Location of bus stops is a complicated subject; by reducing distances between stops, walking time decreases, but the total travel time may increase. In this paper, a specified corridor in the city of Rasht in north of Iran is studied. Firstly, a new formula is presented to calculate the travel time, by which the number of stops and consequently, the travel time can be optimized. An intended corridor with specified number of stops and distances between them is addressed, the related formulas to travel time are created, and its travel time is calculated. Then the corridor is modelled using a meta-heuristic method in order that the placement and the optimal distances of bus stops for that are determined. It was found that alighting and boarding time along with bus capacity are the most effective factors affecting travel time. Consequently, it is better to have more concentration on indicated factors for improving the efficiency of bus system.

  15. Dynamic Bus Travel Time Prediction Models on Road with Multiple Bus Routes

    Science.gov (United States)

    Bai, Cong; Peng, Zhong-Ren; Lu, Qing-Chang; Sun, Jian

    2015-01-01

    Accurate and real-time travel time information for buses can help passengers better plan their trips and minimize waiting times. A dynamic travel time prediction model for buses addressing the cases on road with multiple bus routes is proposed in this paper, based on support vector machines (SVMs) and Kalman filtering-based algorithm. In the proposed model, the well-trained SVM model predicts the baseline bus travel times from the historical bus trip data; the Kalman filtering-based dynamic algorithm can adjust bus travel times with the latest bus operation information and the estimated baseline travel times. The performance of the proposed dynamic model is validated with the real-world data on road with multiple bus routes in Shenzhen, China. The results show that the proposed dynamic model is feasible and applicable for bus travel time prediction and has the best prediction performance among all the five models proposed in the study in terms of prediction accuracy on road with multiple bus routes. PMID:26294903

  16. Dynamic Bus Travel Time Prediction Models on Road with Multiple Bus Routes.

    Science.gov (United States)

    Bai, Cong; Peng, Zhong-Ren; Lu, Qing-Chang; Sun, Jian

    2015-01-01

    Accurate and real-time travel time information for buses can help passengers better plan their trips and minimize waiting times. A dynamic travel time prediction model for buses addressing the cases on road with multiple bus routes is proposed in this paper, based on support vector machines (SVMs) and Kalman filtering-based algorithm. In the proposed model, the well-trained SVM model predicts the baseline bus travel times from the historical bus trip data; the Kalman filtering-based dynamic algorithm can adjust bus travel times with the latest bus operation information and the estimated baseline travel times. The performance of the proposed dynamic model is validated with the real-world data on road with multiple bus routes in Shenzhen, China. The results show that the proposed dynamic model is feasible and applicable for bus travel time prediction and has the best prediction performance among all the five models proposed in the study in terms of prediction accuracy on road with multiple bus routes.

  17. CONSIDERING TRAVEL TIME RELIABILITY AND SAFETY FOR EVALUATION OF CONGESTION RELIEF SCHEMES ON EXPRESSWAY SEGMENTS

    Directory of Open Access Journals (Sweden)

    Babak MEHRAN

    2009-01-01

    Full Text Available Evaluation of the efficiency of congestion relief schemes on expressways has generally been based on average travel time analysis. However, road authorities are much more interested in knowing the possible impacts of improvement schemes on safety and travel time reliability prior to implementing them in real conditions. A methodology is presented to estimate travel time reliability based on modeling travel time variations as a function of demand, capacity and weather conditions. For a subject expressway segment, patterns of demand and capacity were generated for each 5-minute interval over a year by using the Monte-Carlo simulation technique, and accidents were generated randomly according to traffic conditions. A whole year analysis was performed by comparing demand and available capacity for each scenario and shockwave analysis was used to estimate the queue length at each time interval. Travel times were estimated from refined speed-flow relationships and buffer time index was estimated as a measure of travel time reliability. it was shown that the estimated reliability measures and predicted number of accidents are very close to observed values through empirical data. After validation, the methodology was applied to assess the impact of two alternative congestion relief schemes on a subject expressway segment. one alternative was to open the hard shoulder to traffic during the peak period, while the other was to reduce the peak period demand by 15%. The extent of improvements in travel conditions and safety, likewise the reduction in road users' costs after implementing each improvement scheme were estimated. it was shown that both strategies can result in up to 23% reduction in the number of occurred accidents and significant improvements in travel time reliability. Finally, the advantages and challenging issues of selecting each improvement scheme were discussed.

  18. Analysis of Modal Travel Time Variability Due to Mesoscale Ocean Structure

    National Research Council Canada - National Science Library

    Smith, Amy

    1997-01-01

    .... First, for an open ocean environment away from strong boundary currents, the effects of randomly phased linear baroclinic Rossby waves on acoustic travel time are shown to produce a variable overall...

  19. Comparison of methods for measuring travel time at Florida freeways and arterials : [summary].

    Science.gov (United States)

    2014-07-01

    In this project, University of Florida researchers : collected field data along several highways to : evaluate travel time measurements from several : sources: STEWARD, BlueTOAD, INRIX, and HERE. : STEWARD (Statewide Transportation Engineering : Ware...

  20. Incorporating travel-time reliability into the congestion management process : a primer.

    Science.gov (United States)

    2015-02-01

    This primer explains the value of incorporating travel-time reliability into the Congestion Management Process (CMP) : and identifies the most current tools available to assist with this effort. It draws from applied research and best practices : fro...

  1. Freeway travel time estimation using existing fixed traffic sensors : phase 1.

    Science.gov (United States)

    2013-08-01

    Freeway travel time is one of the most useful pieces of information for road users and an : important measure of effectiveness (MOE) for traffic engineers and policy makers. In the Greater : St. Louis area, Gateway Guide, the St. Louis Transportation...

  2. Correlates of time spent walking and cycling to and from work: baseline results from the commuting and health in Cambridge study

    Directory of Open Access Journals (Sweden)

    Panter Jenna

    2011-11-01

    Full Text Available Abstract Purpose Environmental perceptions and psychological measures appear to be associated with walking and cycling behaviour; however, their influence is still unclear. We assessed these associations using baseline data from a quasi-experimental cohort study of the effects of major transport infrastructural developments in Cambridge, UK. Methods Postal surveys were sent to adults who travel to work in Cambridge (n = 1582. Questions asked about travel modes and time spent travelling to and from work in the last week, perceptions of the route, psychological measures regarding car use and socio-demographic characteristics. Participants were classified into one of two categories according to time spent walking for commuting ('no walking' or 'some walking' and one of three categories for cycling ('no cycling', '1-149 min/wk' and ' ≥ 150 min/wk'. Results Of the 1164 respondents (68% female, mean (SD age: 42.3 (11.4 years 30% reported any walking and 53% reported any cycling to or from work. In multiple regression models, short distance to work and not having access to a car showed strong positive associations with both walking and cycling. Furthermore, those who reported that it was pleasant to walk were more likely to walk to or from work (OR = 4.18, 95% CI 3.02 to 5.78 and those who reported that it was convenient to cycle on the route between home and work were more likely to do so (1-149 min/wk: OR = 4.60, 95% CI 2.88 to 7.34; ≥ 150 min/wk: OR = 3.14, 95% CI 2.11 to 4.66. Positive attitudes in favour of car use were positively associated with time spent walking to or from work but negatively associated with cycling to or from work. Strong perceived behavioural control for car use was negatively associated with walking. Conclusions In this relatively affluent sample of commuters, a range of individual and household characteristics, perceptions of the route environment and psychological measures relating to car use were associated with

  3. IYL Blog: Astronomers travel in time and space with light

    Science.gov (United States)

    Mather, John C.

    2015-01-01

    As an astronomer, I use light to travel through the universe, and to look back in time to when the universe was young. So do you! All of us see things as they were when the light was emitted, not as they are now. The farthest thing you can easily see without a telescope is the Andromeda Nebula, which is a galaxy like the Milky Way, about 2.5 million light years away. You see it as it was 2.5 million years ago, and we really don't know what it looks like today; the disk will have rotated a bit, new stars will have been born, there could have been all kinds of exploding stars, and the black hole in the middle could be lighting up. People may be skeptical of the Big Bang theory, even though we have a TV show named for it, but we (I should say Penzias and Wilson) measured its heat radiation 51 years ago at Bell Telephone Labs in New Jersey. Their discovery marks the beginning of the era of cosmology as a measurement science rather than speculation. Penzias and Wilson received the Nobel Prize in 1978 for their finding, which had been predicted in 1948 by Alpher and Herman. By the way, heat radiation is just another form of light - we call it radiation because we can't see it, but it's exactly the same phenomenon of electromagnetic waves, and the only difference is the wavelength. In the old days of analog television, if you tuned your TV in between channels, about 1% of the snow that you could see came from the Big Bang. So when we look at the heat radiation of the early universe, we really are gazing right at what seems to us a cosmic fireball, which surrounds us completely. It's a bit of an illusion; if you can imagine what astronomers in other galaxies would see, they would also feel surrounded by the fireball, and they would also think they were in the middle. So from a mathematical version of imagination, we conclude that there is no observable center and no edge of our universe, and that the heat of the fireball fills the entire universe uniformly. Astronomers are

  4. Variation in Patients' Travel Times among Imaging Examination Types at a Large Academic Health System.

    Science.gov (United States)

    Rosenkrantz, Andrew B; Liang, Yu; Duszak, Richard; Recht, Michael P

    2017-08-01

    Patients' willingness to travel farther distances for certain imaging services may reflect their perceptions of the degree of differentiation of such services. We compare patients' travel times for a range of imaging examinations performed across a large academic health system. We searched the NYU Langone Medical Center Enterprise Data Warehouse to identify 442,990 adult outpatient imaging examinations performed over a recent 3.5-year period. Geocoding software was used to estimate typical driving times from patients' residences to imaging facilities. Variation in travel times was assessed among examination types. The mean expected travel time was 29.2 ± 20.6 minutes, but this varied significantly (p travel times were shortest for ultrasound (26.8 ± 18.9) and longest for positron emission tomography-computed tomography (31.9 ± 21.5). For magnetic resonance imaging, travel times were shortest for musculoskeletal extremity (26.4 ± 19.2) and spine (28.6 ± 21.0) examinations and longest for prostate (35.9 ± 25.6) and breast (32.4 ± 22.3) examinations. For computed tomography, travel times were shortest for a range of screening examinations [colonography (25.5 ± 20.8), coronary artery calcium scoring (26.1 ± 19.2), and lung cancer screening (26.4 ± 14.9)] and longest for angiography (32.0 ± 22.6). For ultrasound, travel times were shortest for aortic aneurysm screening (22.3 ± 18.4) and longest for breast (30.1 ± 19.2) examinations. Overall, men (29.9 ± 21.6) had longer (p travel times than women (27.8 ± 20.3); this difference persisted for each modality individually (p ≤ 0.006). Patients' willingness to travel longer times for certain imaging examination types (particularly breast and prostate imaging) supports the role of specialized services in combating potential commoditization of imaging services. Disparities in travel times by gender warrant further investigation. Copyright

  5. APPLICATION OF TRAVEL TIME RELIABILITY FOR PERFORMANCE ORIENTED OPERATIONAL PLANNING OF EXPRESSWAYS

    Science.gov (United States)

    Mehran, Babak; Nakamura, Hideki

    Evaluation of impacts of congestion improvement scheme s on travel time reliability is very significant for road authorities since travel time reliability repr esents operational performance of expressway segments. In this paper, a methodology is presented to estimate travel tim e reliability prior to implementation of congestion relief schemes based on travel time variation modeling as a function of demand, capacity, weather conditions and road accident s. For subject expressway segmen ts, traffic conditions are modeled over a whole year considering demand and capacity as random variables. Patterns of demand and capacity are generated for each five minute interval by appl ying Monte-Carlo simulation technique, and accidents are randomly generated based on a model that links acci dent rate to traffic conditions. A whole year analysis is performed by comparing de mand and available capacity for each scenario and queue length is estimated through shockwave analysis for each time in terval. Travel times are estimated from refined speed-flow relationships developed for intercity expressways and buffer time index is estimated consequently as a measure of travel time reliability. For validation, estimated reliability indices are compared with measured values from empirical data, and it is shown that the proposed method is suitable for operational evaluation and planning purposes.

  6. A simple method to assess unsaturated zone time lag in the travel time from ground surface to receptor.

    Science.gov (United States)

    Sousa, Marcelo R; Jones, Jon P; Frind, Emil O; Rudolph, David L

    2013-01-01

    In contaminant travel from ground surface to groundwater receptors, the time taken in travelling through the unsaturated zone is known as the unsaturated zone time lag. Depending on the situation, this time lag may or may not be significant within the context of the overall problem. A method is presented for assessing the importance of the unsaturated zone in the travel time from source to receptor in terms of estimates of both the absolute and the relative advective times. A choice of different techniques for both unsaturated and saturated travel time estimation is provided. This method may be useful for practitioners to decide whether to incorporate unsaturated processes in conceptual and numerical models and can also be used to roughly estimate the total travel time between points near ground surface and a groundwater receptor. This method was applied to a field site located in a glacial aquifer system in Ontario, Canada. Advective travel times were estimated using techniques with different levels of sophistication. The application of the proposed method indicates that the time lag in the unsaturated zone is significant at this field site and should be taken into account. For this case, sophisticated and simplified techniques lead to similar assessments when the same knowledge of the hydraulic conductivity field is assumed. When there is significant uncertainty regarding the hydraulic conductivity, simplified calculations did not lead to a conclusive decision. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. A Kind of Urban Road Travel Time Forecasting Model with Loop Detectors

    OpenAIRE

    Zhu, Guangyu; Wang, Li; Zhang, Peng; Song, Kang

    2016-01-01

    Urban road travel time is an important parameter to reflect the traffic flow state. Besides, it is one of the important parameters for the traffic management department to formulate guidance measures, provide traffic information service, and improve the efficiency of the detectors group. Therefore, it is crucial to improve the forecast accuracy of travel time in traffic management practice. Based on the analysis of the change-point and the ARIMA model, this paper constructs a model for the ma...

  8. Leisure and the Opportunity Cost of Travel Time in Recreation Demand Analysis: A Re-Examination

    OpenAIRE

    Amoako-Tuffour, Joe; Martınez-Espineira, Roberto

    2008-01-01

    Using count data models that account for zero-truncation, overdispersion, and endogenous stratification, this paper estimates the value of access to recreational parks. The focus is on the valuation of the opportunity cost of travel time within the cost of the trip and its effects on estimated consumer surplus. The fraction of hourly earnings that corresponds to the opportunity cost of travel time is endogenously estimated as a function of visitor characteristics, rather than fixed exogenousl...

  9. Racial disparities in travel time to radiotherapy facilities in the Atlanta metropolitan area.

    Science.gov (United States)

    Peipins, Lucy A; Graham, Shannon; Young, Randall; Lewis, Brian; Flanagan, Barry

    2013-07-01

    Low-income women with breast cancer who rely on public transportation may have difficulty in completing recommended radiation therapy due to inadequate access to radiation facilities. Using a geographic information system (GIS) and network analysis we quantified spatial accessibility to radiation treatment facilities in the Atlanta, Georgia metropolitan area. We built a transportation network model that included all bus and rail routes and stops, system transfers and walk and wait times experienced by public transportation system travelers. We also built a private transportation network to model travel times by automobile. We calculated travel times to radiation therapy facilities via public and private transportation from a population-weighted center of each census tract located within the study area. We broadly grouped the tracts by low, medium and high household access to a private vehicle and by race. Facility service areas were created using the network model to map the extent of areal coverage at specified travel times (30, 45 and 60 min) for both public and private modes of transportation. The median public transportation travel time to the nearest radiotherapy facility was 56 min vs. approximately 8 min by private vehicle. We found that majority black census tracts had longer public transportation travel times than white tracts across all categories of vehicle access and that 39% of women in the study area had longer than 1 h of public transportation travel time to the nearest facility. In addition, service area analyses identified locations where the travel time barriers are the greatest. Spatial inaccessibility, especially for women who must use public transportation, is one of the barriers they face in receiving optimal treatment. Published by Elsevier Ltd.

  10. Time Spent by Calliphora Spp. Blowflies on Standard Traps Baited with Liver and Ammonia

    Directory of Open Access Journals (Sweden)

    Florica Morariu

    2010-10-01

    Full Text Available The larvae of blowflies from the Calliphoridae family cause fly strikes in sheep and other species of economic importance. Impaired wool, decrease of ewe fertility, and even death can occur in heavy infestations. This paper describes the Calliphora spp. blowflies’ behavior on and around a trap baited with liver and ammonia before they entered in. More than half of Calliphora spp. blowflies (50.88% stayed a medium time (eight to fourteen seconds on the standard trap, while only 1.79% of them spent a longer time (26 to 30 seconds before entering the trap.

  11. Uncertainty and Sensitivity of Contaminant Travel Times from the Upgradient Nevada Test Site to the Yucca Mountain Area

    Energy Technology Data Exchange (ETDEWEB)

    J. Zhu; K. Pohlmann; J. Chapman; C. Russell; R.W.H. Carroll; D. Shafer

    2009-09-10

    Yucca Mountain (YM), Nevada, has been proposed by the U.S. Department of Energy as the nation’s first permanent geologic repository for spent nuclear fuel and highlevel radioactive waste. In this study, the potential for groundwater advective pathways from underground nuclear testing areas on the Nevada Test Site (NTS) to intercept the subsurface of the proposed land withdrawal area for the repository is investigated. The timeframe for advective travel and its uncertainty for possible radionuclide movement along these flow pathways is estimated as a result of effective-porosity value uncertainty for the hydrogeologic units (HGUs) along the flow paths. Furthermore, sensitivity analysis is conducted to determine the most influential HGUs on the advective radionuclide travel times from the NTS to the YM area. Groundwater pathways are obtained using the particle tracking package MODPATH and flow results from the Death Valley regional groundwater flow system (DVRFS) model developed by the U.S. Geological Survey (USGS). Effectiveporosity values for HGUs along these pathways are one of several parameters that determine possible radionuclide travel times between the NTS and proposed YM withdrawal areas. Values and uncertainties of HGU porosities are quantified through evaluation of existing site effective-porosity data and expert professional judgment and are incorporated in the model through Monte Carlo simulations to estimate mean travel times and uncertainties. The simulations are based on two steady-state flow scenarios, the pre-pumping (the initial stress period of the DVRFS model), and the 1998 pumping (assuming steady-state conditions resulting from pumping in the last stress period of the DVRFS model) scenarios for the purpose of long-term prediction and monitoring. The pumping scenario accounts for groundwater withdrawal activities in the Amargosa Desert and other areas downgradient of YM. Considering each detonation in a clustered region around Pahute Mesa (in

  12. Uncertainty and Sensitivity of Contaminant Travel Times from the Upgradient Nevada Test Site to the Yucca Mountain Area

    International Nuclear Information System (INIS)

    Zhu, J.; Pohlmann, K.; Chapman, J.; Russell, C.; Carroll, R.W.H.; Shafer, D.

    2009-01-01

    Yucca Mountain (YM), Nevada, has been proposed by the U.S. Department of Energy as the nation's first permanent geologic repository for spent nuclear fuel and high-level radioactive waste. In this study, the potential for groundwater advective pathways from underground nuclear testing areas on the Nevada Test Site (NTS) to intercept the subsurface of the proposed land withdrawal area for the repository is investigated. The timeframe for advective travel and its uncertainty for possible radionuclide movement along these flow pathways is estimated as a result of effective-porosity value uncertainty for the hydrogeologic units (HGUs) along the flow paths. Furthermore, sensitivity analysis is conducted to determine the most influential HGUs on the advective radionuclide travel times from the NTS to the YM area. Groundwater pathways are obtained using the particle tracking package MODPATH and flow results from the Death Valley regional groundwater flow system (DVRFS) model developed by the U.S. Geological Survey (USGS). Effective porosity values for HGUs along these pathways are one of several parameters that determine possible radionuclide travel times between the NTS and proposed YM withdrawal areas. Values and uncertainties of HGU porosities are quantified through evaluation of existing site effective-porosity data and expert professional judgment and are incorporated in the model through Monte Carlo simulations to estimate mean travel times and uncertainties. The simulations are based on two steady-state flow scenarios, the pre-pumping (the initial stress period of the DVRFS model), and the 1998 pumping (assuming steady-state conditions resulting from pumping in the last stress period of the DVRFS model) scenarios for the purpose of long-term prediction and monitoring. The pumping scenario accounts for groundwater withdrawal activities in the Amargosa Desert and other areas downgradient of YM. Considering each detonation in a clustered region around Pahute Mesa (in

  13. The Optimization of Passengers’ Travel Time under Express-Slow Mode Based on Suburban Line

    Directory of Open Access Journals (Sweden)

    Xiaobing Ding

    2016-01-01

    Full Text Available The suburban line connects the suburbs and the city centre; it is of huge advantage to attempt the express-slow mode. The passengers’ average travel time is the key factor to reflect the level of rail transport services, especially under the express-slow mode. So it is important to study the passengers’ average travel time under express-slow, which can get benefit on the optimization of operation scheme. First analyze the main factor that affects passengers’ travel time and then mine the dynamic interactive relationship among the factors. Second, a new passengers’ travel time evolution algorithm is proposed after studying the stop schedule and the proportion of express/slow train, and then membrane computing theory algorithm is introduced to solve the model. Finally, Shanghai Metro Line 22 is set as an example to apply the optimization model to calculate the total passengers’ travel time; the result shows that the total average travel time under the express-slow mode can save 1 minute and 38 seconds; the social influence and value of it are very huge. The proposed calculation model is of great help for the decision of stop schedule and provides theoretical and methodological support to determine the proportion of express/slow trains, improves the service level, and enriches and complements the rail transit operation scheme optimization theory system.

  14. Flow modelling to estimate suspended sediment travel times for two Canadian Deltas

    Directory of Open Access Journals (Sweden)

    S. R. Fassnacht

    2000-01-01

    Full Text Available The approximate travel times for suspended sediment transport through two multi-channel networks are estimated using flow modelling. The focus is on the movement of high sediment concentrations that travel rapidly downstream. Since suspended sediment transport through river confluences and bifurcation movement is poorly understood, it is assumed that the sediment moves at approximately the average channel velocity during periods of high sediment load movement. Calibration of the flow model is discussed, with an emphasis on the incorporation of cross-section data, that are not referenced to a datum, using a continuous water surface profile. Various flow regimes are examined for the Mackenzie and the Slave River Deltas in the Northwest Territories, Canada, and a significant variation in travel times is illustrated. One set of continuous daily sediment measurements throughout the Mackenzie Delta is used to demonstrate that the travel time estimates are reasonable. Keywords: suspended sediment; multi-channel river systems; flow modelling; sediment transport

  15. Model-based Integration of Past & Future in TimeTravel

    DEFF Research Database (Denmark)

    Khalefa, Mohamed E.; Fischer, Ulrike; Pedersen, Torben Bach

    2012-01-01

    We demonstrate TimeTravel, an efficient DBMS system for seamless integrated querying of past and (forecasted) future values of time series, allowing the user to view past and future values as one joint time series. This functionality is important for advanced application domain like energy....... The main idea is to compactly represent time series as models. By using models, the TimeTravel system answers queries approximately on past and future data with error guarantees (absolute error and confidence) one order of magnitude faster than when accessing the time series directly. In addition...... it to answer approximate and exact queries. TimeTravel is implemented into PostgreSQL, thus achieving complete user transparency at the query level. In the demo, we show the easy building of a hierarchical model index for a real-world time series and the effect of varying the error guarantees on the speed up...

  16. Estimating Travel Time in Bank Filtration Systems from a Numerical Model Based on DTS Measurements.

    Science.gov (United States)

    des Tombe, Bas F; Bakker, Mark; Schaars, Frans; van der Made, Kees-Jan

    2018-03-01

    An approach is presented to determine the seasonal variations in travel time in a bank filtration system using a passive heat tracer test. The temperature in the aquifer varies seasonally because of temperature variations of the infiltrating surface water and at the soil surface. Temperature was measured with distributed temperature sensing along fiber optic cables that were inserted vertically into the aquifer with direct push equipment. The approach was applied to a bank filtration system consisting of a sequence of alternating, elongated recharge basins and rows of recovery wells. A SEAWAT model was developed to simulate coupled flow and heat transport. The model of a two-dimensional vertical cross section is able to simulate the temperature of the water at the well and the measured vertical temperature profiles reasonably well. MODPATH was used to compute flowpaths and the travel time distribution. At the study site, temporal variation of the pumping discharge was the dominant factor influencing the travel time distribution. For an equivalent system with a constant pumping rate, variations in the travel time distribution are caused by variations in the temperature-dependent viscosity. As a result, travel times increase in the winter, when a larger fraction of the water travels through the warmer, lower part of the aquifer, and decrease in the summer, when the upper part of the aquifer is warmer. © 2017 The Authors. Groundwater published by Wiley Periodicals, Inc. on behalf of National Ground Water Association.

  17. Time-use and well-being impacts of travel-to-work and travel-for-work

    OpenAIRE

    Wheatley, D; Bickerton, C

    2016-01-01

    This article contributes to understanding of the complex patterns of travel-to-work and travel-for-work which \\ud increasingly characterize highly skilled employment, using 2015 data from a UK Midlands study comprising an online survey and follow-up interviews. Travel-to-work essentially lengthens the working day, and is difficult to use productively, especially when commuting by car. Travel-for-work, by contrast, results in intense schedules \\ud especially when requiring overnight stays. Own...

  18. Existence and Stability of Traveling Waves for Degenerate Reaction-Diffusion Equation with Time Delay

    Science.gov (United States)

    Huang, Rui; Jin, Chunhua; Mei, Ming; Yin, Jingxue

    2018-01-01

    This paper deals with the existence and stability of traveling wave solutions for a degenerate reaction-diffusion equation with time delay. The degeneracy of spatial diffusion together with the effect of time delay causes us the essential difficulty for the existence of the traveling waves and their stabilities. In order to treat this case, we first show the existence of smooth- and sharp-type traveling wave solutions in the case of c≥c^* for the degenerate reaction-diffusion equation without delay, where c^*>0 is the critical wave speed of smooth traveling waves. Then, as a small perturbation, we obtain the existence of the smooth non-critical traveling waves for the degenerate diffusion equation with small time delay τ >0 . Furthermore, we prove the global existence and uniqueness of C^{α ,β } -solution to the time-delayed degenerate reaction-diffusion equation via compactness analysis. Finally, by the weighted energy method, we prove that the smooth non-critical traveling wave is globally stable in the weighted L^1 -space. The exponential convergence rate is also derived.

  19. Existence and Stability of Traveling Waves for Degenerate Reaction-Diffusion Equation with Time Delay

    Science.gov (United States)

    Huang, Rui; Jin, Chunhua; Mei, Ming; Yin, Jingxue

    2018-06-01

    This paper deals with the existence and stability of traveling wave solutions for a degenerate reaction-diffusion equation with time delay. The degeneracy of spatial diffusion together with the effect of time delay causes us the essential difficulty for the existence of the traveling waves and their stabilities. In order to treat this case, we first show the existence of smooth- and sharp-type traveling wave solutions in the case of c≥c^* for the degenerate reaction-diffusion equation without delay, where c^*>0 is the critical wave speed of smooth traveling waves. Then, as a small perturbation, we obtain the existence of the smooth non-critical traveling waves for the degenerate diffusion equation with small time delay τ >0. Furthermore, we prove the global existence and uniqueness of C^{α ,β }-solution to the time-delayed degenerate reaction-diffusion equation via compactness analysis. Finally, by the weighted energy method, we prove that the smooth non-critical traveling wave is globally stable in the weighted L^1-space. The exponential convergence rate is also derived.

  20. Penanganan Fuzzy Time Window pada Travelling Salesman Problem (TSP dengan Penerapan Algoritma Genetika

    Directory of Open Access Journals (Sweden)

    Gusti Eka Yuliastuti

    2017-03-01

    Full Text Available The route of the travel tour packages offered by travel agents is not considered optimum, so the level of satisfaction the tourist is not maximal. Selection of the route of the travel packages included in the traveling salesman problem (TSP. The problem that occurs is uncertain tourists visiting destinations at the best destinations timing hereinafter be referred to as the fuzzy time window problem. Therefore, the authors apply the genetic algorithm to solve the problem. Based on test results obtained optimum solution with the fitness value of 1.3291, a population size of 100, the number of generations of 1000, a combination of CR=0,4 and MR=0.6.

  1. Psychological, interpersonal, and clinical factors predicting time spent on physical activity among Mexican patients with hypertension.

    Science.gov (United States)

    Ybarra Sagarduy, José Luis; Camacho Mata, Dacia Yurima; Moral de la Rubia, José; Piña López, Julio Alfonso; Yunes Zárraga, José Luis Masud

    2018-01-01

    It is widely known that physical activity is the key to the optimal management and clinical control of hypertension. This research was conducted to identify factors that can predict the time spent on physical activity among Mexican adults with hypertension. This cross-sectional study was conducted among 182 Mexican patients with hypertension, who completed a set of self-administered questionnaires related to personality, social support, and medical adherence and health care behaviors, body mass index, and time since the disease diagnosis. Several path analyses were performed in order to test the predictors of the study behavior. Lower tolerance to frustration, more tolerance to ambiguity, more effective social support, and less time since the disease diagnosis predicted more time spent on physical activity, accounting for 13.3% of the total variance. The final model shows a good fit to the sample data ( p BS =0.235, χ 2 / gl =1.519, Jöreskog and Sörbom's Goodness of Fit Index =0.987, adjusted modality =0.962, Bollen's Incremental Fit Index =0.981, Bentler-Bonett Normed Fit Index =0.946, standardized root mean square residual =0.053). The performance of physical activity in patients with hypertension depends on a complex set of interactions between personal, interpersonal, and clinical variables. Understanding how these factors interact might enhance the design of interdisciplinary intervention programs so that quality of life of patients with hypertension improves and they might be able to manage and control their disease well.

  2. Narrative time in video games and films: from loop to travel in time

    Directory of Open Access Journals (Sweden)

    Lluís Anyó

    2015-09-01

    Full Text Available Within the broad framework of audiovisual theories, this paper deals with the analysis of narrative time in video games. Starting with the concept of participation time, which is taken from the interactive media, the now classic concepts of the narratology of film studies are applied to clarify the main mutual influences between the two media in relation to narrative time. Unlike the cinema, the narrative character of video games is not always clear. Generally, video games are always games and often also stories. Certainly, the playable character of these stories confers on them a few specific characteristics that need to be explored. Two aspects of narrative time are relevant here. Firstly, the loop as an elementary control structure of computer programming and as a characteristic narrative form of time structure in video games, and secondly, the paradox of travel in time in the discrepancy between the time order at the level of the story and at the level of the narrative.

  3. Exploring the acceptable travel time concept in the US and European contexts. Results from Berkeley, CA and Delft, The Netherlands

    NARCIS (Netherlands)

    Milakis, D.; van Wee, G.P.

    2016-01-01

    “Do people consider an acceptable travel time?” We raised this question in Milakis, Cervero, and van Wee (2015) to explore the validity of the acceptable travel time concept as a possible factor in the travel and destination decision-making process. Results from interviews with 20 subjects in

  4. Role of Travel Time Information on Day-to-Day Route Choice Behavior Based on Real-World Experiments

    NARCIS (Netherlands)

    van Essen, Mariska; Thomas, Tom; Chorus, Caspar; van Berkum, Eric C.

    2016-01-01

    It is widely believed that travel time information leads to reductions in traffic congestion and thereby improves network efficiency. An important research topic within travel behavior research is therefore how car drivers choose their routes, specifically when they receive travel time information.

  5. A Quantitative Analysis of the Relationship Between Radiation Therapy Use and Travel Time.

    Science.gov (United States)

    Liu, Emma; Santibáñez, Pablo; Puterman, Martin L; Weber, Leah; Ma, Xiang; Sauré, Antoine; Olivotto, Ivo A; Halperin, Ross; French, John; Tyldesley, Scott

    2015-11-01

    To model and quantify the relationship between radiation therapy (RT) use and travel time to RT services. Population-based registries and databases were used to identify both incident cancer patient and patients receiving RT within 1 year of diagnosis (RT1y) in British Columbia, Canada, between 1992 and 2011. The effects of age, gender, diagnosis year, income, prevailing wait time, and travel duration for RT on RT1y were assessed. Significant factors from univariate analyses were included in a multivariable logistic regression model. The shape of the travel time-RT1y curve was represented by generalized additive and segmented regression models. Analyses were conducted for breast, lung, and genitourinary cancer separately and for all cancer sites combined. After adjustment for age, gender, diagnosis year, income, and prevailing wait times, increasing travel time to the closest RT facility had a negative impact RT1y. The shape of the travel time-RT1y curve varied with cancer type. For breast cancer, the odds of RT1y were constant for the first 2 driving hours and decreased at 17% per hour thereafter. For lung cancer, the odds of RT1y decreased by 16% after 20 minutes and then decreased at 6% per hour. Genitourinary cancer RT1y was relatively independent of travel time. For all cancer sites combined, the odds of RT1y were constant within the first 2 driving hours and decreased at 7% per hour thereafter. Travel time to receive RT has a different impact on RT1y for different tumor sites. The results provide evidence-based insights for the configuration of catchment areas for new and existing cancer centers providing RT. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  6. Dynamic Travel Time Prediction Models for Buses Using Only GPS Data

    Directory of Open Access Journals (Sweden)

    Wei Fan

    2015-01-01

    Full Text Available Providing real-time and accurate travel time information of transit vehicles can be very helpful as it assists passengers in planning their trips to minimize waiting times. The purpose of this research is to develop and compare dynamic travel time prediction models which can provide accurate prediction of bus travel time in order to give real-time information at a given downstream bus stop using only global positioning system (GPS data. Historical Average (HA, Kalman Filtering (KF and Artificial Neural Network (ANN models are considered and developed in this paper. A case has been studied by making use of the three models. Promising results are obtained from the case study, indicating that the models can be used to implement an Advanced Public Transport System. The implementation of this system could assist transit operators in improving the reliability of bus services, thus attracting more travelers to transit vehicles and helping relieve congestion. The performances of the three models were assessed and compared with each other under two criteria: overall prediction accuracy and robustness. It was shown that the ANN outperformed the other two models in both aspects. In conclusion, it is shown that bus travel time information can be reasonably provided using only arrival and departure time information at stops even in the absence of traffic-stream data.

  7. How do passion for video games and needs frustration explain time spent gaming?

    Science.gov (United States)

    Mills, Devin J; Milyavskaya, Marina; Mettler, Jessica; Heath, Nancy L; Derevensky, Jeffrey L

    2018-04-01

    Research applying self-determination theory and the dualistic model of passion (DMP) has shown video games may satisfy basic psychological needs (i.e., competence, autonomy, and relatedness) and be identified as a passion. The DMP distinguishes between healthy or harmonious passion and problematic or obsessive passion (OP), with the latter reflecting an overreliance towards one's passion to obtain needs satisfaction. The experience of daily obstructions to needs satisfaction, or needs frustration (NF), may facilitate such an overreliance. This study explored how NF and both types of passion explain the amount of time that university students spend gaming. The overall association between NF and time spent gaming was not significant. However, for video game users with low levels of OP for gaming, there was a significant negative association between NF and time spent gaming. Additionally, evidence of a mutually reinforcing association between NF and OP for gaming indicates that a vicious cycle exists, whereby a strong OP for gaming predicts and is reinforced by greater NF. The theoretical implications are discussed. © 2018 The British Psychological Society.

  8. Perinatal outcomes and travel time from home to hospital: Welsh data from 1995 to 2009.

    Science.gov (United States)

    Paranjothy, Shantini; Watkins, W John; Rolfe, Kim; Adappa, Roshan; Gong, Yi; Dunstan, Frank; Kotecha, Sailesh

    2014-12-01

    To study the association between travel time from home to hospital and birth outcomes. For all registrable births to women resident in Wales (1995-2009), we calculated the travel time between the mother's residence and the postcode-based location for both the birth hospital and all hospitals with maternity services that were open. Using logistic regression, we obtained odds ratios for the association between travel time and each birth outcome, adjusted for confounders. In our analysis of 412 827 singleton births, for every 15-min increase in travel time to the birth hospital, there was an increased risk of early (n = 609; OR: 1.13; 95%CI: 1.07, 1.20) and late neonatal death (n = 251; OR: 1.15; 95%CI: 1.05, 1.26). Results for intrapartum stillbirth were inconclusive (n = 135; OR: 1.13; 95%CI: 0.98, 1.30). For the above-combined (n = 995) results, we get OR: 1.15, 95%CI: 1.09, 1.20. No association was found with travel time to the nearest hospital (OR: 1.01; 95%CI: 0.90, 1.13 per 15-min increase in travel time) for the composite outcome of intrapartum stillbirth and neonatal deaths. Longer travel time to the birth hospital was associated with increased risk of neonatal deaths, but there was no strong evidence of association with the geographical location of maternity services. ©2014 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  9. Time travel in the homogeneous Som-Raychaudhuri Universe

    International Nuclear Information System (INIS)

    Paiva, F.M.; Reboucas, M.J.; Teixeira, A.F.F.

    1987-01-01

    Properties of the rotating Som-Raychaudhuri homogeneous space-time are investigated: time-like and null geodesics, causality features, horizons and invariant characterization. An integral representation of its five isometries is also discussed. (author) [pt

  10. Urban Link Travel Time Prediction Based on a Gradient Boosting Method Considering Spatiotemporal Correlations

    Directory of Open Access Journals (Sweden)

    Faming Zhang

    2016-11-01

    Full Text Available The prediction of travel times is challenging because of the sparseness of real-time traffic data and the intrinsic uncertainty of travel on congested urban road networks. We propose a new gradient–boosted regression tree method to accurately predict travel times. This model accounts for spatiotemporal correlations extracted from historical and real-time traffic data for adjacent and target links. This method can deliver high prediction accuracy by combining simple regression trees with poor performance. It corrects the error found in existing models for improved prediction accuracy. Our spatiotemporal gradient–boosted regression tree model was verified in experiments. The training data were obtained from big data reflecting historic traffic conditions collected by probe vehicles in Wuhan from January to May 2014. Real-time data were extracted from 11 weeks of GPS records collected in Wuhan from 5 May 2014 to 20 July 2014. Based on these data, we predicted link travel time for the period from 21 July 2014 to 25 July 2014. Experiments showed that our proposed spatiotemporal gradient–boosted regression tree model obtained better results than gradient boosting, random forest, or autoregressive integrated moving average approaches. Furthermore, these results indicate the advantages of our model for urban link travel time prediction.

  11. Road Short-Term Travel Time Prediction Method Based on Flow Spatial Distribution and the Relations

    Directory of Open Access Journals (Sweden)

    Mingjun Deng

    2016-01-01

    Full Text Available There are many short-term road travel time forecasting studies based on time series, but indeed, road travel time not only relies on the historical travel time series, but also depends on the road and its adjacent sections history flow. However, few studies have considered that. This paper is based on the correlation of flow spatial distribution and the road travel time series, applying nearest neighbor and nonparametric regression method to build a forecasting model. In aspect of spatial nearest neighbor search, three different space distances are defined. In addition, two forecasting functions are introduced: one combines the forecasting value by mean weight and the other uses the reciprocal of nearest neighbors distance as combined weight. Three different distances are applied in nearest neighbor search, which apply to the two forecasting functions. For travel time series, the nearest neighbor and nonparametric regression are applied too. Then minimizing forecast error variance is utilized as an objective to establish the combination model. The empirical results show that the combination model can improve the forecast performance obviously. Besides, the experimental results of the evaluation for the computational complexity show that the proposed method can satisfy the real-time requirement.

  12. 78 FR 26649 - Agency Information Collection Activities: Trusted Traveler Programs

    Science.gov (United States)

    2013-05-07

    ... keepers from the collection of information (total capital/startup costs and operations and maintenance... to the traveler is less time spent in line waiting to be processed. These Trusted Traveler programs... reflect a revised estimated time to complete the Global Entry application. The burden hours also reflect...

  13. A Quantitative Analysis of the Relationship Between Radiation Therapy Use and Travel Time

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Emma; Santibáñez, Pablo [British Columbia Cancer Agency, Vancouver, British Columbia (Canada); Puterman, Martin L. [Sauder School of Business, University of British Columbia, Vancouver, British Columbia (Canada); Weber, Leah; Ma, Xiang [British Columbia Cancer Agency, Vancouver, British Columbia (Canada); Sauré, Antoine [Sauder School of Business, University of British Columbia, Vancouver, British Columbia (Canada); Olivotto, Ivo A.; Halperin, Ross; French, John [British Columbia Cancer Agency, Vancouver, British Columbia (Canada); Tyldesley, Scott, E-mail: styldesl@bccancer.bc.ca [British Columbia Cancer Agency, Vancouver, British Columbia (Canada)

    2015-11-01

    Purpose: To model and quantify the relationship between radiation therapy (RT) use and travel time to RT services. Methods and Materials: Population-based registries and databases were used to identify both incident cancer patient and patients receiving RT within 1 year of diagnosis (RT1y) in British Columbia, Canada, between 1992 and 2011. The effects of age, gender, diagnosis year, income, prevailing wait time, and travel duration for RT on RT1y were assessed. Significant factors from univariate analyses were included in a multivariable logistic regression model. The shape of the travel time–RT1y curve was represented by generalized additive and segmented regression models. Analyses were conducted for breast, lung, and genitourinary cancer separately and for all cancer sites combined. Results: After adjustment for age, gender, diagnosis year, income, and prevailing wait times, increasing travel time to the closest RT facility had a negative impact RT1y. The shape of the travel time–RT1y curve varied with cancer type. For breast cancer, the odds of RT1y were constant for the first 2 driving hours and decreased at 17% per hour thereafter. For lung cancer, the odds of RT1y decreased by 16% after 20 minutes and then decreased at 6% per hour. Genitourinary cancer RT1y was relatively independent of travel time. For all cancer sites combined, the odds of RT1y were constant within the first 2 driving hours and decreased at 7% per hour thereafter. Conclusions: Travel time to receive RT has a different impact on RT1y for different tumor sites. The results provide evidence-based insights for the configuration of catchment areas for new and existing cancer centers providing RT.

  14. A Quantitative Analysis of the Relationship Between Radiation Therapy Use and Travel Time

    International Nuclear Information System (INIS)

    Liu, Emma; Santibáñez, Pablo; Puterman, Martin L.; Weber, Leah; Ma, Xiang; Sauré, Antoine; Olivotto, Ivo A.; Halperin, Ross; French, John; Tyldesley, Scott

    2015-01-01

    Purpose: To model and quantify the relationship between radiation therapy (RT) use and travel time to RT services. Methods and Materials: Population-based registries and databases were used to identify both incident cancer patient and patients receiving RT within 1 year of diagnosis (RT1y) in British Columbia, Canada, between 1992 and 2011. The effects of age, gender, diagnosis year, income, prevailing wait time, and travel duration for RT on RT1y were assessed. Significant factors from univariate analyses were included in a multivariable logistic regression model. The shape of the travel time–RT1y curve was represented by generalized additive and segmented regression models. Analyses were conducted for breast, lung, and genitourinary cancer separately and for all cancer sites combined. Results: After adjustment for age, gender, diagnosis year, income, and prevailing wait times, increasing travel time to the closest RT facility had a negative impact RT1y. The shape of the travel time–RT1y curve varied with cancer type. For breast cancer, the odds of RT1y were constant for the first 2 driving hours and decreased at 17% per hour thereafter. For lung cancer, the odds of RT1y decreased by 16% after 20 minutes and then decreased at 6% per hour. Genitourinary cancer RT1y was relatively independent of travel time. For all cancer sites combined, the odds of RT1y were constant within the first 2 driving hours and decreased at 7% per hour thereafter. Conclusions: Travel time to receive RT has a different impact on RT1y for different tumor sites. The results provide evidence-based insights for the configuration of catchment areas for new and existing cancer centers providing RT.

  15. [Travel time and distances to Norwegian out-of-hours casualty clinics].

    Science.gov (United States)

    Raknes, Guttorm; Morken, Tone; Hunskår, Steinar

    2014-11-01

    Geographical factors have an impact on the utilisation of out-of-hours services. In this study we have investigated the travel distance to out-of-hours casualty clinics in Norwegian municipalities in 2011 and the number of municipalities covered by the proposed recommendations for secondary on-call arrangements due to long distances. We estimated the average maximum travel times and distances in Norwegian municipalities using a postcode-based method. Separate analyses were performed for municipalities with a single, permanently located casualty clinic. Altogether 417 out of 430 municipalities were included. We present the median value of the maximum travel times and distances for the included municipalities. The median maximum average travel distance for the municipalities was 19 km. The median maximum average travel time was 22 minutes. In 40 of the municipalities (10 %) the median maximum average travel time exceeded 60 minutes, and in 97 municipalities (23 %) the median maximum average travel time exceeded 40 minutes. The population of these groups comprised 2 % and 5 % of the country's total population respectively. For municipalities with permanent emergency facilities(N = 316), the median average flight time 16 minutes and median average distance 13 km.. In many municipalities, the inhabitants have a long average journey to out-of-hours emergency health services, but seen as a whole, the inhabitants of these municipalities account for a very small proportion of the Norwegian population. The results indicate that the proposed recommendations for secondary on-call duty based on long distances apply to only a small number of inhabitants. The recommendations should therefore be adjusted and reformulated to become more relevant.

  16. Associations between maternal employment and time spent in nutrition-related behaviours among German children and mothers.

    Science.gov (United States)

    Möser, Anke; Chen, Susan E; Jilcott, Stephanie B; Nayga, Rodolfo M

    2012-07-01

    To examine associations between maternal employment and time spent engaging in nutrition-related behaviours among mothers and children using a nationally representative sample of households in West and East Germany. A cross-sectional analysis was performed using time-use data for a sample of mother-child dyads. Associations between maternal employment and time spent in nutrition-related activities such as eating at home, eating away from home and food preparation were estimated using a double-hurdle model. German Time Budget Survey 2001/02. The overall sample included 1071 households with a child between 10 and 17 years of age. The time-use data were collected for a 3 d period of observation (two weekdays and one weekend day). Maternal employment was associated with the time children spent on nutrition-related behaviours. In households with employed mothers, children spent more time eating alone at home and less time eating meals with their mothers. Moreover, employed mothers spent less time on meal preparation compared with non-employed mothers. There were regional differences in time spent on nutrition-related behaviours, such that East German children were more likely to eat at home alone than West German children. Maternal employment was associated with less time spent eating with children and preparing food, which may be related to the increasing childhood obesity rates in Germany. Future national surveys that collect both time-use data and health outcomes could yield further insight into mechanisms by which maternal time use might be associated with health outcomes among children.

  17. HELIOSEISMIC SIGNATURE OF CHROMOSPHERIC DOWNFLOWS IN ACOUSTIC TRAVEL-TIME MEASUREMENTS FROM HINODE

    International Nuclear Information System (INIS)

    Nagashima, Kaori; Sekii, Takashi; Kosovichev, Alexander G.; Zhao Junwei; Tarbell, Theodore D.

    2009-01-01

    We report on a signature of chromospheric downflows in two emerging flux regions detected by time-distance helioseismology analysis. We use both chromospheric intensity oscillation data in the Ca II H line and photospheric Dopplergrams in the Fe I 557.6 nm line obtained by Hinode/SOT for our analyses. By cross-correlating the Ca II oscillation signals, we have detected a travel-time anomaly in the plage regions; outward travel times are shorter than inward travel times by 0.5-1 minute. However, such an anomaly is absent in the Fe I data. These results can be interpreted as evidence of downflows in the lower chromosphere. The downflow speed is estimated to be below 10 km s -1 . This result demonstrates a new possibility of studying chromospheric flows by time-distance analysis.

  18. Ground-water travel time calculations for the potential nuclear repository site at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Younker, J.L.; Wilson, W.E.; Sinnock, S.

    1986-01-01

    In support of the US Department of Energy Nevada Nuclear Waste Storage Investigations Project, ground-water travel times were calculated for flow paths in both the saturated and unsaturated zones at Yucca Mountain, a potential site for a high-level radioactive waste repository in southern Nevada. The calculations were made through a combined effort by Science Applications International Corporation, Sandia National Laboratories, and the US Geological Survey. Travel times in the unsaturated zone were estimated by dividing the flow path length by the ground-water velocity, where velocities were obtained by dividing the vertical flux by the effective porosity of the rock types along assumed vertical flow paths. Saturated zone velocities were obtained by dividing the product of the bulk hydraulic conductivity and hydraulic gradient by the effective porosity. Total travel time over an EPA-established 5-km flow path was then calculated to be the sum of the travel times in the two parts of the flow path. Estimates of ground water fluxes and travel times are critical for evaluating the favorability of the Yucca Mountain site because they provide the basis for estimating the potential for radionuclides to reach the accessible environment within certain time limits

  19. Investigation of Bicycle Travel Time Estimation Using Bluetooth Sensors for Low Sampling Rates

    Directory of Open Access Journals (Sweden)

    Zhenyu Mei

    2014-10-01

    Full Text Available Filtering the data for bicycle travel time using Bluetooth sensors is crucial to the estimation of link travel times on a corridor. The current paper describes an adaptive filtering algorithm for estimating bicycle travel times using Bluetooth data, with consideration of low sampling rates. The data for bicycle travel time using Bluetooth sensors has two characteristics. First, the bicycle flow contains stable and unstable conditions. Second, the collected data have low sampling rates (less than 1%. To avoid erroneous inference, filters are introduced to “purify” multiple time series. The valid data are identified within a dynamically varying validity window with the use of a robust data-filtering procedure. The size of the validity window varies based on the number of preceding sampling intervals without a Bluetooth record. Applications of the proposed algorithm to the dataset from Genshan East Road and Moganshan Road in Hangzhou demonstrate its ability to track typical variations in bicycle travel time efficiently, while suppressing high frequency noise signals.

  20. Development of a measurement approach to assess time children participate in organized sport, active travel, outdoor active play, and curriculum-based physical activity.

    Science.gov (United States)

    Borghese, Michael M; Janssen, Ian

    2018-03-22

    Children participate in four main types of physical activity: organized sport, active travel, outdoor active play, and curriculum-based physical activity. The objective of this study was to develop a valid approach that can be used to concurrently measure time spent in each of these types of physical activity. Two samples (sample 1: n = 50; sample 2: n = 83) of children aged 10-13 wore an accelerometer and a GPS watch continuously over 7 days. They also completed a log where they recorded the start and end times of organized sport sessions. Sample 1 also completed an outdoor time log where they recorded the times they went outdoors and a description of the outdoor activity. Sample 2 also completed a curriculum log where they recorded times they participated in physical activity (e.g., physical education) during class time. We describe the development of a measurement approach that can be used to concurrently assess the time children spend participating in specific types of physical activity. The approach uses a combination of data from accelerometers, GPS, and activity logs and relies on merging and then processing these data using several manual (e.g., data checks and cleaning) and automated (e.g., algorithms) procedures. In the new measurement approach time spent in organized sport is estimated using the activity log. Time spent in active travel is estimated using an existing algorithm that uses GPS data. Time spent in outdoor active play is estimated using an algorithm (with a sensitivity and specificity of 85%) that was developed using data collected in sample 1 and which uses all of the data sources. Time spent in curriculum-based physical activity is estimated using an algorithm (with a sensitivity of 78% and specificity of 92%) that was developed using data collected in sample 2 and which uses accelerometer data collected during class time. There was evidence of excellent intra- and inter-rater reliability of the estimates for all of these types of

  1. A pilot study into the perception of unreliability of travel times using in-depth interviews

    NARCIS (Netherlands)

    Tseng, Y.-Y.; Verhoef, E.; de Jong, G.; Kouwenhoven, M.; van der Hoorn, T.

    2009-01-01

    Transport investments normally reduce travel times, but may also reduce unreliability. Conventional time gains can be evaluated in cost benefit analysis using standard values of time. For valuing reliability gains, however, no standard measures are readily available. The Dutch Ministry of Transport

  2. Birth weight and time spent in outdoor physical activity during adolescence.

    Science.gov (United States)

    Gopinath, Bamini; Hardy, Louise L; Baur, Louise A; Burlutsky, George; Mitchell, Paul

    2013-03-01

    We investigated the association between birth parameters (weight, length, and head circumference) and time spent in physical activity (outdoor and indoor) and screen time (TV viewing, computer, and videogame usage) among adolescents. A longitudinal cohort study surveyed 1794 children in 2004-2005 (median age = 12.7 yr), and 752 were resurveyed 5 yr later in 2009-2010 (age = 17-18 yr). Adolescents completed detailed activity questionnaires. Parents extracted birth parameter data from their child's health record booklet. After adjusting for age, sex, ethnicity, gestational age, parental education, home ownership, exposure to passive smoking, and body mass index, 12-yr-old children in the highest compared with the lowest quartile of birth weight spent on average approximately 56 and 62 min more in total (Ptrend = 0.02) and outdoor physical activity (Ptrend = 0.02) per week, respectively. Similarly, 12-yr-old children in the high (>4000 g) versus very low (adolescence. Hence, this could be part of the underlying mechanism between prenatal influences and future disease risk and could have possible clinical implications.

  3. Automated methods for real-time analysis of spent-fuel measurement data

    International Nuclear Information System (INIS)

    Bosler, G.E.; Rinard, P.M.; Klosterbuer, S.F.; Painter, J.

    1988-01-01

    Software has been developed for ''real-time'' analysis of neutron and gamma data from GRAND-1/fork measurements on spent-fuel assemblies. Three modules compose the software package. The modules are linked through a database system of files. The first module is part of a general data-base processing code. This module prepares input data files with inventory and correction-factor information for the second module. The second module, called OLAF, operates on a computer attached to the GRAND-1 electronics unit. In this second module, neutron and gamma data from spent-fuel assemblies are analyzed to verify consistency in the facility operator declarations for exposure (burnup) and cooling time. From the analysis, potential discrepancies in the measurement data are questioned while equipment is still installed at the facility and is available for additional measurements. During the measurements, data are written to an output file, called a results file, which can be processed by the third module of the software package. In the third module, printed reports summarizing the data and results are prepared, and neutron and gamma data are written to files that are process by the Deming curve-fitting code

  4. Time spent sitting during and outside working hours in bus drivers: A pilot study.

    Science.gov (United States)

    Varela-Mato, Veronica; Yates, Thomas; Stensel, David J; Biddle, Stuart J H; Clemes, Stacy A

    2016-06-01

    This cross-sectional pilot study objectively measured sedentary and non-sedentary time in a sample of bus drivers from the East Midlands, United Kingdom. Participants wore an activPAL3 inclinometer for 7 days and completed a daily diary. Driver's blood pressure, heart rate, waist circumference and body composition were measured objectively at the outset. The proportions of time spent sedentary and non-sedentary were calculated during waking hours on workdays and non-workdays and during working-hours and non-working-hours on workdays. 28 (85% of those enrolled into the study) provided valid objective monitoring data (89.3% male, [median ± IQR] age: 45.2 ± 12.8 years, BMI 28.1 ± 5.8 kg/m(2)). A greater proportion of time was spent sitting on workdays than non-workdays (75% [724 ± 112 min/day] vs. 62% [528 ± 151 min/day]; p working-hours than non-working-hours (83% [417 ± 88 min/day] vs. 68% [307 ± 64 min/day]; p less than 3% of their overall time stepping. Bus drivers accumulate high levels of sitting time during working-hours and outside working-hours. Interventions are urgently needed in this at-risk group, which should focus on reducing sitting and increasing movement during breaks and increasing physical activity during leisure time to improve cardiovascular health.

  5. Relationship of Near-Crash/Crash Risk to Time Spent on a Cell Phone While Driving.

    Science.gov (United States)

    Farmer, Charles M; Klauer, Sheila G; McClafferty, Julie A; Guo, Feng

    2015-01-01

    The objective of this study was to examine in a naturalistic driving setting the dose-response relationship between cell phone usage while driving and risk of a crash or near crash. How is the increasing use of cell phones by drivers associated with overall near-crash/crash risk (i.e., during driving times both on and off the phone)? Day-to-day driving behavior of 105 volunteer subjects was monitored over a period of 1 year. A random sample was selected comprised of 4 trips from each month that each driver was in the study, and in-vehicle video was used to classify driver behavior. The proportion of driving time spent using a cell phone was estimated for each 3-month period and correlated with overall crash and near-crash rates for each period. Thus, it was possible to test whether changes in an individual driver's cell phone use over time were associated with changes in overall near-crash/crash risk. Drivers in the study spent 11.7% of their driving time interacting with a cell phone, primarily talking on the phone (6.5%) or simply holding the phone in their hand or lap (3.7%). The risk of a near-crash/crash event was approximately 17% higher when the driver was interacting with a cell phone, due primarily to actions of reaching for/answering/dialing, which nearly triples risk (relative risk = 2.84). However, the amount of driving time spent interacting with a cell phone did not affect a driver's overall near-crash/crash risk. Vehicle speeds within 6 s of the beginning of each call on average were 5-6 mph lower than speeds at other times. Results of this naturalistic driving study are consistent with the observation that increasing cell phone use in the general driving population has not led to increased crash rates. Although cell phone use can be distracting and crashes have occurred during this distraction, overall crash rates appear unaffected by changes in the rate of cell phone use, even for individual drivers. Drivers compensate somewhat for the distraction

  6. Effective time management: surgery, research, service, travel, fitness, and family.

    Science.gov (United States)

    Porta, C Rees; Anderson, Michael R; Steele, Scott R

    2013-12-01

    Over 1,500 years ago, the St. Benedictine Monks used planning and strict schedules to increase their productivity. Since then, surgeons have developed several different strategies to manage our time effectively. Finding a balance among career, family, and hobbies is essential for maintaining satisfaction and optimizing productivity. Several recurring themes throughout the medical literature offer potential solutions to help maximize the little time surgeons possess. In this article, we will explore some of the methods and strategies available to help surgeons minimize waste and make the most of the most precious commodity we have-our time.

  7. Pn seismic wave travel time at the Semipalatinsk Test Site - Borovoe seismic station trace

    International Nuclear Information System (INIS)

    An, V.A.; Kaazik, P.B.; Ovchinnikov, V.M.

    2001-01-01

    This paper preparation involved 160 explosions at the Degelen Site conducted in 1961-1989 and 89 explosions at the Balapan Site conducted in 1968-1989. Pn wave travel time was tied to the sea level in accordance with velocity characteristics of the explosion hypocenter medium; and to average epicentral distance for every site basing on their local travel time curves of Pn wave relative to Borovoe station. Maximum amplitude of mean-year travel times variations is 0.3-0.5 s as at the Nevada Test Site - Borovoe trace and Mirniy (Antarctica). However, the linear trend in contrast to previous traces has negative sign (0.08 s for Degelen and 0.1 s for Balapan). Thus, Pn wave velocity increases with calendar time. (author)

  8. Modelling perception updating of travel times in the context of departure time choice under ITS

    NARCIS (Netherlands)

    Ettema, D.F.; Timmermans, H.J.P.; Arentze, T.A.

    2004-01-01

    Traffic information is increasingly regarded as a tool to achieve a more efficient use of the road network. As traffic information is often applied in the context of routitine trips, the question arises how travellers integrate traffic information with the knowledge of travel conditions gained

  9. Time-Of-Travel Tool Protects Drinking Water

    Science.gov (United States)

    The Lower Susquehanna Source Water Protection (SWP) Partnership utilizes the Incident Command Tool for Drinking Water Protection (ICWater) to support the Pennsylvania Department of Environmental Protection (PADEP) with real-time spill tracking information.

  10. Branch-and-cut-and-price for the traveling salesman problem with time windows

    DEFF Research Database (Denmark)

    Røpke, Stefan; Madsen, Oli B.G.

    In the traveling salesman problem with time windows (TSPTW) one is given a depot and a set of nodes to be visited by a salesman. The salesman starts his trip at the depot and must visit all nodes while respecting time windows at the nodes. The objective of the problem is to minimize the total...... distance traveled by the salesman. The TSPTW is formulated as a set-partitioning problem which is solved by using combined cut and column generation. The pricing sub problem in the column generation procedure is a shortest path problem with time window constraints and 2-cycle elimination. A standard column...

  11. Exploring heterogeneity in travel time expenditure of aging populations in the Netherlands : results of a CHAID analysis

    NARCIS (Netherlands)

    Yang, D.; Timmermans, H.J.P.; Grigolon, A.B.

    2013-01-01

    The aim of this paper is to contribute to the increasing literature on travel behavior and time use of the elderly. The Dutch National Travel Survey, administered in 2009, was used as a data source. First, various facets of activity-travel patterns of the elderly were compared against overall sample

  12. Determination of burnup, cooling time and initial enrichment of PWR spent fuel by use of gamma-ray activity ratios

    International Nuclear Information System (INIS)

    Min, D.K.; Park, H.J.; Park, K.J.; Ro, S.G.; Park, H.S.

    1999-01-01

    The Korea Atomic Energy Institute has been developing the algorithms for sequential determination of cooling time, initial enrichment and burnup of the PWR spent fuel assembly by use of gamma ratio measurements, i.e. 134 Cs/ 137 Cs, 154 Eu/ 137 Cs and 106 Ru 137 Cs/( 134 Cs) 2 . Calculations were performed by applying the ORIGEN-S code. This method has advantages over combination techniques of neutron and gamma measurement, because of its simplicity and insensitivity to the measurement geometry. For verifying the algorithms an experiment for determining the cooling time, initial enrichment and burnup of the two PWR spent fuel rods was conducted by use of high-resolution gamma detector (HPGe) system only. This paper describes the method used and interim results of the experiment. This method can be applied for spent fuel characterization, burnup credit and safeguards of the spent fuel management facility

  13. Being (un)moved by mental time travel

    NARCIS (Netherlands)

    Stins, J.F.; Habets, L.; Jongeling, R.; Canal Bruland, R.

    Mental imagery of events in the past or future, and of unpleasant or pleasant events, has been found to lead to spontaneous backward/forward bodily motions. Both time and emotion are represented along a spatial continuum, and activation of these representations seems to be simulated in spontaneous

  14. Assessment of Smolt Condition for Travel Time Analysis Project, 1987-1997 Project Review.

    Energy Technology Data Exchange (ETDEWEB)

    Schrock, Robin M.; Hans, Karen M.; Beeman, John W. [US Geological Survey, Western Fisheries Research Center, Columbia River Research Laboratory, Cook, WA

    1997-12-01

    The assessment of Smolt Condition for Travel Time Analysis Project (Bonneville Power Administration Project 87-401) monitored attributes of salmonid smolt physiology in the Columbia and Snake River basins from 1987 to 1997, under the Northwest Power Planning Council Fish and Wildlife Program, in cooperation with the Smolt Monitoring Program of the Fish Passage Center. The primary goal of the project was to investigate the physiological development of juvenile salmonids related to migration rates. The assumption was made that the level of smolt development, interacting with environmental factos such as flow, would be reflected in travel times. The Fish Passage Center applied the physiological measurements of smolt condition to Water Budget management, to regulate flows so as to decrease travel time and increase survival.

  15. Between-mode-differences in the value of travel time: Self-selection or strategic behaviour?

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Hjorth, Katrine; Lyk-Jensen, Stéphanie Vincent

    2010-01-01

    Using stated preference survey data, we measure the value of travel time for several transport modes. We find, like many before us, that the value of travel time varies across modes in the opposite direction of what would be the consequence of differences in comfort. We examine three candidate...... causes for the observed differences: Comfort effects, self-selection and strategic behaviour of respondents. Using experiments with both the current and an alternative mode we find that the differences in the value of travel time are consistent with self-selection and comfort effects. Moreover......, respondents having bus as the current or the alternative mode seem not to value comfort differently across modes. Strategic behaviour seems to play no role....

  16. Application of Google-based Data for Travel Time Analysis: Kaunas City Case Study

    Directory of Open Access Journals (Sweden)

    Vytautas Dumbliauskas

    2017-12-01

    Full Text Available Recently, new traffic data sources have emerged raising new challenges and opportunities when applying novel methodologies. The purpose of this research is to analyse car travel time data collected from smartphones by Google Company. Geographic information system (GIS tools and Python programming language were employed in this study to establish the initial framework as well as to automatically extract, analyse, and visualize data. The analysis resulted in the calculation of travel time fluctuation during the day, calculation of travel time variability and estimation of origin-destination (OD skim matrices. Furthermore, we accomplished the accessibility analysis and provided recommendations for further research.

  17. Uncertainty and sensitivity results for pre-waste-emplacement groundwater travel time

    International Nuclear Information System (INIS)

    Kaplan, P.G.

    1992-01-01

    In this paper uncertainty and sensitivity analyses for pre-waste-emplacement groundwater travel time conducted. Although preliminary, a numbed of interesting results were obtained. Uncertainty in the ground water travel time statistics, as measured by the coefficient of variation, increases and then decrease as the modeled system transitions from matrix-dominated to fracture-dominated flow. The uncertainty analysis also suggests that the median, as opposed to the mean, may be a better indicator of performance with respect to the regulatory criterion. The sensitivity analysis shows a strong correlation between an effective fracture property, fracture porosity, and failure to meet the regulatory pre-waste-emplacement groundwater travel time criterion of 1,000 years

  18. Effect of the time spent by the photon in the absorbed state on the time-dependent transfer of radiation

    International Nuclear Information System (INIS)

    Rao, D.M.; Rangarajan, K.E.; Peraiah, A.

    1990-01-01

    The time-dependent transfer equation is derived for a two-level atomic model which takes both bound-bound and bound-free transitions into account. A numerical scheme is proposed for solving the monochromatic time-dependent transfer equation when the time spent by the photon in the absorbed state is significant. The method can be easily extended to solve the problem of time-dependent line formation of the bound-free continuum. It is used here to study three types of boundary conditions of the incident radiation incident on a scattering atmosphere. The quantitative results show that the relaxation of the radiation field depends on the optical depth of the medium and on the ray's angle of emergence. 21 refs

  19. On Throughput Maximization in Constant Travel-Time Robotic Cells

    OpenAIRE

    Milind Dawande; Chelliah Sriskandarajah; Suresh Sethi

    2002-01-01

    We consider the problem of scheduling operations in bufferless robotic cells that produce identical parts. The objective is to find a cyclic sequence of robot moves that minimizes the long-run average time to produce a part or, equivalently, maximizes the throughput rate. The robot can be moved in simple cycles that produce one unit or, in more complicated cycles, that produce multiple units. Because one-unit cycles are the easiest to understand, implement, and control, they are widely used i...

  20. "I can see clearly now": The effect of cue imageability on mental time travel

    DEFF Research Database (Denmark)

    Rasmussen, Katrine Willemoes; Berntsen, Dorthe

    2014-01-01

    Mental time travel (MTT) is the ability to mentally project oneself backward or forward in time, in order to remember an event from one’s personal past or to imagine a possible event in one’s personal future. Recent work has suggested that, although past and future MTT may rely on shared...

  1. Access to destinations : arterial data acquisition and network-wide travel time estimation (phase II).

    Science.gov (United States)

    2010-03-01

    The objectives of this project were to (a) produce historic estimates of travel times on Twin-Cities arterials : for 1995 and 2005, and (b) develop an initial architecture and database that could, in the future, produce timely : estimates of arterial...

  2. Measuring cross-border travel times for freight : Otay Mesa international border crossing.

    Science.gov (United States)

    2010-09-01

    Cross border movement of people and goods is a vital part of the North American economy. Accurate real-time data on travel times along the US-Mexico border can help generate a range of tangible benefits covering improved operations and security, lowe...

  3. Incorporating space-time constraints and activity-travel time profiles in a multi-state supernetwork approach to individual activity-travel scheduling

    NARCIS (Netherlands)

    Liao, F.; Arentze, T.A.; Timmermans, H.J.P.

    2013-01-01

    Activity-travel scheduling is at the core of many activity-based models that predict short-term effects of travel information systems and travel demand management. Multi-state supernetworks have been advanced to represent in an integral fashion the multi-dimensional nature of activity-travel

  4. Preliminary study of visual perspective in mental time travel in schizophrenia.

    Science.gov (United States)

    Wang, Ya; Wang, Yi; Zhao, Qing; Cui, Ji-Fang; Hong, Xiao-Hong; Chan, Raymond Ck

    2017-10-01

    This study explored specificity and visual perspective of mental time travel in schizophrenia. Fifteen patients with schizophrenia and 18 controls were recruited. Participants were asked to recall or imagine specific events according to cue words. Results showed that schizophrenia patients generated fewer specific events than controls, the recalled events were more specific than imagined events. Schizophrenia adopted less field perspective and more observer perspective than controls. These results suggested that patients with schizophrenia were impaired in mental time travel both in specificity and visual perspective. Further studies are needed to identify the underlying mechanisms. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. LHC 2008 talks Peut-on voyager dans le temps? (Is time travel possible?)

    CERN Multimedia

    2008-01-01

    Scientific magazines (and sometimes even scientists themselves) regularly talk about the possibility of travelling through time. It has also been the subject of many science-fiction novels. We will first discuss what we mean when we talk about time travel, then explain what contemporary physics has to say about it. Thursday, 12 June 2008 at 8.00 p.m. Peut-on voyager dans le temps ? Etienne Klein Physicist at CEA and Doctor of Philosophy of Science The Globe, first floor No specialist knowledge required. Entrance free. http://www.cern.ch/globe

  6. Mental time travel to the future might be reduced in sleep.

    Science.gov (United States)

    Speth, Jana; Schloerscheidt, Astrid M; Speth, Clemens

    2017-02-01

    We present a quantitative study of mental time travel to the future in sleep. Three independent, blind judges analysed a total of 563 physiology-monitored mentation reports from sleep onset, REM sleep, non-REM sleep, and waking. The linguistic tool for the mentation report analysis is based on established grammatical and cognitive-semantic theories and has been validated in previous studies. Our data indicate that REM and non-REM sleep must be characterized by a reduction in mental time travel to the future, which would support earlier physiological evidence at the level of brain function. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. The role of ground-water travel time in suitability and licensing

    International Nuclear Information System (INIS)

    Murphy, M.R.

    1995-01-01

    This paper examines the Department of Energy (DOE) guidelines and Nuclear Regulatory Commission (NRC) licensing criteria pertaining to groundwater travel time, and their impact on obtaining a license for Yucca Mountain. DOE will be able to obtain a license for Yucca Mountain even if it is determined that there are some fast pathways along which groundwater travel time to the accessible environment is less than 1000 years. However, this will require DOE to gather and analyze a significant amount of firm data, rather than relying primarily on conservative assumptions and bounding calculations

  8. Reliable Rescue Routing Optimization for Urban Emergency Logistics under Travel Time Uncertainty

    Directory of Open Access Journals (Sweden)

    Qiuping Li

    2018-02-01

    Full Text Available The reliability of rescue routes is critical for urban emergency logistics during disasters. However, studies on reliable rescue routing under stochastic networks are still rare. This paper proposes a multiobjective rescue routing model for urban emergency logistics under travel time reliability. A hybrid metaheuristic integrating ant colony optimization (ACO and tabu search (TS was designed to solve the model. An experiment optimizing rescue routing plans under a real urban storm event, was carried out to validate the proposed model. The experimental results showed how our approach can improve rescue efficiency with high travel time reliability.

  9. Visuospatial asymmetries and emotional valence influence mental time travel.

    Science.gov (United States)

    Thomas, Nicole A; Takarangi, Melanie K T

    2018-06-01

    Spatial information is tightly intertwined with temporal and valence-based information. Namely, "past" is represented on the left, and "future" on the right, along a horizontal mental timeline. Similarly, right is associated with positive, whereas left is negative. We developed a novel task to examine the effects of emotional valence and temporal distance on mental representations of time. We compared positivity biases, where positive events are positioned closer to now, and right hemisphere emotion biases, where negative events are positioned to the left. When the entire life span was used, a positivity bias emerged; positive events were closer to now. When timeline length was reduced, positivity and right hemisphere emotion biases were consistent for past events. In contrast, positive and negative events were equidistant from now in the future condition, suggesting positivity and right hemisphere emotion biases opposed one another, leading events to be positioned at a similar distance. We then reversed the timeline by moving past to the right and future to the left. Positivity biases in the past condition were eliminated, and negative events were placed slightly closer to now in the future condition. We conclude that an underlying left-to-right mental representation of time is necessary for positivity biases to emerge for past events; however, our mental representations of future events are inconsistent with positivity biases. These findings point to an important difference in the way in which we represent the past and the future on our mental timeline. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  10. Time spent in housework and leisure: links with parents' physiological recovery from work.

    Science.gov (United States)

    Saxbe, Darby E; Repetti, Rena L; Graesch, Anthony P

    2011-04-01

    Spouses' balancing of housework and leisure activities at home may affect their recovery from work. This paper reports on a study of everyday family life in which 30 dual-earner couples were tracked around their homes by researchers who recorded their locations and activities every 10 min. For women, the most frequently pursued activities at home were housework, communication, and leisure; husbands spent the most time in leisure activities, followed by communication and housework. Spouses differed in their total time at home and their proportion of time devoted to leisure and housework activities, with wives observed more often in housework and husbands observed more often in leisure activities. Both wives and husbands who devoted more time to housework had higher levels of evening cortisol and weaker afternoon-to-evening recovery. For wives, husbands' increased housework time also predicted stronger evening cortisol recovery. When both spouses' activities were entered in the same model, leisure predicted husbands' evening cortisol, such that husbands who apportioned more time to leisure, and whose wives apportioned less time to leisure, showed stronger after-work recovery. These results suggest that the division of labor within couples may have implications for physical health.

  11. Effect of travel distance and time to radiotherapy on likelihood of receiving mastectomy.

    Science.gov (United States)

    Goyal, Sharad; Chandwani, Sheenu; Haffty, Bruce G; Demissie, Kitaw

    2015-04-01

    Breast-conserving surgery (BCS) followed by adjuvant radiation therapy (RT) is the standard of care for women with early-stage breast cancer as an alternative to mastectomy. The purpose of this study was to examine the relationship between receipt of mastectomy and travel distance and time to RT facility in New Jersey (NJ). Data were collected from a cohort of 634 NJ women diagnosed with early-stage breast cancer. In patients receiving RT, the precise RT facility was used, whereas in patients not receiving RT, surgeons were contacted to determine the location of RT referral. Travel distance and time to RT facility from the patients' residential address were modeled separately using multiple binomial regression to examine their association with choice of surgery while adjusting for clinical and sociodemographic factors. Overall, 58.5 % patients underwent BCS with median travel distance to the radiation facility of 4.8 miles (vs. 6.6 miles for mastectomy) and median travel time of 12.0 min (vs. 15.0 min for mastectomy). Patients residing > 9.2 miles compared with ≤ 9.2 miles from radiation facility were 44 % more likely to receive mastectomy. Additionally, patients requiring > 19 min compared with ≤ 19 min of travel time were 36 % more likely to receive mastectomy. These data found that travel distance and time from RT facility act as barriers to undergoing BCS in women with early-stage breast cancer. Despite being in an urban region, a significant number of women in NJ with early-stage breast cancer did not receive BCS.

  12. Time spent for activation of non-profit studies in oncology in Italy.

    Directory of Open Access Journals (Sweden)

    Gianfranco De Feo

    Full Text Available AIM: The aim of this paper is to describe the time spent to activate oncological non-profit clinical trials promoted in Italy by the National Cancer Institute of Naples, following the implementation of recent European laws. METHODOLOGY: Data about the process of activation of 5 non-profit multicentre clinical trials were prospectively collected through a web-based system. The impact of European guidelines was assessed by comparing the efficiency of the process between applications started before and after the decree introducing in Italy the Clinical Trial Application form (MD-CTA. Outcomes of the descriptive analyses were the time to EC opinion, the time to administrative agreement signature after a positive EC opinion, and the cumulative percentage of submissions that came to closure (either positive or negative within four subsequent time cohorts. PRINCIPAL FINDINGS: From March 2007 to October 2009, 202 applications were submitted to 107 centres. Forty-four (59% applications of those submitted before were successful, compared to 71 (55% of those submitted after MD-CTA. Most of the failures were due to missing EC response (27% and 22% or administrative reasons (10% and 16%, before and after, respectively; very few (4% and 7% were due to EC refusal. The impact of the MD-CTA on time to EC opinion looked positive (median 4.1 vs 2.4 months, before and after, respectively but a subgroup analysis revealed that the impact was limited to a comparison biased by the selection of EC. After a positive EC opinion, there was no difference before and after MD-CTA in the time to administrative agreement signature (median 3.6 and 3.8 months, respectively. A trend to shortening time to closure of the whole submission process over the time was evident, with 58% of the applications coming to closure within 6 months from submission in the most recent cohort. CONCLUSIONS: In our experience there is reassuring evidence of a trend toward shortening the time spent to

  13. Electron and VLF travel time differences for wave-particle interactions at L=4: Pt. 2

    International Nuclear Information System (INIS)

    Rash, J.P.S.; Scourfield, M.W.J.; Dougherty, M.K.

    1984-01-01

    The cyclotron resonance or gyroresonance interaction has been widely invoked as a generation mechanism for discrete VLF emissions and plasmaspheric hiss. This interaction involves electrons and VLF waves travelling in opposite directions along a geomagnetic field line. We examine, for an interaction region in the equatorial plane at L=4, the energy of the resonant electrons as a function of VLF wave frequency and ambient equatorial electron density. Then for two different spatial configurations of the interaction and two standard plasma distribution models we examine the difference in travel times to a ground-based observer in the Southern hemisphere for the electrons and waves taking part in the interaction. This difference in travel times is shown as a function of VLF wave frequency and equatorial electron density. The results, and their significance for observations of auroral electrons and VLF at Sanae, Antarctica, are discussed and compared with similar results for the Cerenkov interaction discussed in an earlier paper

  14. Estimating time and travel costs incurred in clinic based screening: flexible sigmoidoscopy screening for colorectal cancer.

    Science.gov (United States)

    Frew, E; Wolstenholme, J L; Atkin, W; Whynes, D K

    1999-01-01

    To identify the characteristics of mode of travel to screening clinics; to estimate the time and travel costs incurred in attending; to investigate whether such costs are likely to bias screening compliance. Twelve centres in the trial of flexible sigmoidoscopy screening for colorectal cancer, drawn from across Great Britain. Analysis of 3525 questionnaires completed by screening subjects while attending clinics. Information supplied included sociodemographic characteristics, modes of travel, expenses, activities foregone owing to attendance, and details of companions. More than 80% of subjects arrived at the clinics by car, and about two thirds were accompanied. On average, the clinic visit involved a 14.4 mile (22.8 km) round trip, requiring 130 minutes. Mean travel costs amounted to 6.10 Pounds per subject. The mean gross direct non-medical and indirect cost per subject amounted to 16.90 Pounds, and the mean overall gross cost per attendance was 22.40 Pounds. Compared with the Great Britain population as a whole, non-manual classes were more strongly represented, and the self employed less strongly represented, among the attendees. In relation to direct medical costs, the time and travel costs of clinic based screening can be substantial, may influence the overall cost effectiveness of a screening programme, and may deter potential subjects from attending.

  15. Data Mining Techniques to Estimate Plutonium, Initial Enrichment, Burnup, and Cooling Time in Spent Fuel Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Trellue, Holly Renee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Fugate, Michael Lynn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tobin, Stephen Joesph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-19

    The Next Generation Safeguards Initiative (NGSI), Office of Nonproliferation and Arms Control (NPAC), National Nuclear Security Administration (NNSA) of the U.S. Department of Energy (DOE) has sponsored a multi-laboratory, university, international partner collaboration to (1) detect replaced or missing pins from spent fuel assemblies (SFA) to confirm item integrity and deter diversion, (2) determine plutonium mass and related plutonium and uranium fissile mass parameters in SFAs, and (3) verify initial enrichment (IE), burnup (BU), and cooling time (CT) of facility declaration for SFAs. A wide variety of nondestructive assay (NDA) techniques were researched to achieve these goals [Veal, 2010 and Humphrey, 2012]. In addition, the project includes two related activities with facility-specific benefits: (1) determination of heat content and (2) determination of reactivity (multiplication). In this research, a subset of 11 integrated NDA techniques was researched using data mining solutions at Los Alamos National Laboratory (LANL) for their ability to achieve the above goals.

  16. Achieving the timely receipt of foreign research reactor spent nuclear fuel at the Savannah River site

    International Nuclear Information System (INIS)

    Brizes, C.M.; Clark, W.D; Thomas, J.; Andes, T.

    1998-01-01

    The May 1996 Record of Decision on a Proposed Nuclear Weapons Nonproliferation Policy Concerning Foreign Research Reactor Spent Nuclear Fuel states that the United States will accept spent nuclear fuel containing uranium of U.S.-origin from foreign research reactors through the year 2009. The best information available indicates that approximately 13,000 assemblies of Material Test Reactor (MTR) spent nuclear fuel from 29 countries are expected to be shipped to the Savannah River Site during the 13 years of the program. As of July 1998, 1,371 spent nuclear fuel assemblies from 12 foreign research reactors have been received at the SRS. That is, after more than two years of the FRR program (approximately 15 percent of the program time), 11 percent of the total assemblies have been received at SRS. Current projections show that most of the assemblies can be received by 2009, however if some of the eligible, non-participating countries decide to rejoin the program, a bottleneck would occur at the end of the program. Also adding to the potential for the bottleneck is a trend of shipments being moved out in the timeline. The Savannah River Site is working to be proactive in avoiding a bottleneck at the end of the program, but cooperation is required from all program participants to be successful. Activities currently in progress include inventory/information questionnaires, verifying fuel against cask(s) certificate of compliance (C. of C.), and collecting Appendix A information well in advance of shipping the SNF. The inventory/information sheets have been distributed to a select number of reactor facilities in the past, but work is in progress to refine the process. Information requested in the questionnaire includes inventory numbers, preferred shipping dates, and cask preferences. This information allows for improved shipment planning and helps to ensure that we are working to meet the needs of the reactor facilities. Current plans are to send the questionnaires to

  17. Long time storage containers for spent fuels and vitrified wastes: synthesis of the studies

    International Nuclear Information System (INIS)

    Beziat, A.

    2004-01-01

    This report presents a synthesis of the studies relatives to the containers devoted to the long time spent fuels storage and vitrified wastes packages. These studies were realized in the framework of the axis 3 of the law of 1991 on the radioactive wastes management. The first part is devoted to the presentation of the studies. The container sizing studies which constitute the first containment barrier are then presented. The material choice and the closed system are also detailed. The studies were validate by the realization of containers models and an associated demonstration program is proposed. A synthesis of the technical and economical studies allowed to determine the components and operation costs. (A.L.B.)

  18. Novel S-35 Intrinsic Tracer Method for Determining Groundwater Travel Time near Managed Aquifer Recharge Facilities

    Science.gov (United States)

    Urióstegui, S. H.; Bibby, R. K.; Esser, B. K.; Clark, J. F.

    2013-12-01

    Identifying groundwater travel times near managed aquifer recharge (MAR) facilities is a high priority for protecting public and environmental health. For MAR facilities in California that incorporate tertiary wastewater into their surface-spreading recharge practices, the target subsurface residence time is >9 months to allow for the natural inactivation and degradation of potential contaminants (less time is needed for full advanced treated water). Established intrinsic groundwater tracer techniques such as tritium/helium-3 dating are unable to resolve timescales of method using a naturally occurring radioisotope of sulfur, sulfur-35 (S-35). After its production in the atmosphere by cosmic ray interaction with argon, S-35 enters the hydrologic cycle as dissolved sulfate through precipitation The short half-life of S-35 (3 months) is ideal for investigating recharge and transport of MAR groundwater on the method, however, has not been applied to MAR operations because of the difficulty in measuring S-35 with sufficient sensitivity in high-sulfate waters. We have developed a new method and have applied it at two southern California MAR facilities where groundwater travel times have previously been characterized using deliberate tracers: 1) Rio Hondo Spreading Grounds in Los Angeles County, and 2) Orange County Groundwater Recharge Facilities in Orange County. Reasonable S-35 travel times of method also identified seasonal patterns in subsurface travel times, which may not be revealed by a deliberate tracer study that is dependent on the hydrologic conditions during the tracer injection period.

  19. Protective effect of time spent walking on risk of stroke in older men.

    Science.gov (United States)

    Jefferis, Barbara J; Whincup, Peter H; Papacosta, Olia; Wannamethee, S Goya

    2014-01-01

    Older adults have the highest risks of stroke and the lowest physical activity levels. It is important to quantify how walking (the predominant form of physical activity in older age) is associated with stroke. A total of 4252 men from a UK population-based cohort reported usual physical activity (regular walking, cycling, recreational activity, and sport) in 1998 to 2000. Nurses took fasting blood samples and made anthropometric measurements. Among 3435 ambulatory men free from cardiovascular disease and heart failure in 1998 to 2000, 195 first strokes occurred during 11-year follow-up. Men walked a median of 7 (interquartile range, 3-12) hours/wk; walking more hours was associated with lower heart rate, D-dimer, and higher forced expiratory volume in 1 second. Compared with men walking 0 to 3 hours/wk, men walking 4 to 7, 8 to 14, 15 to 21, and >22 hours had age- and region-adjusted hazard ratios (95% confidence intervals) for stroke of 0.89 (0.60-1.31), 0.63 (0.40-1.00), 0.68 (0.35-1.32), and 0.36 (0.14-0.91), respectively, P (trend)=0.006. Hazard ratios were somewhat attenuated by adjustment for established and novel risk markers (inflammatory and hemostatic markers and cardiac function [N-terminal pro-brain natriuretic peptide]) and walking pace, but linear trends remained. There was little evidence for a dose-response relationship between walking pace and stroke; comparing average pace or faster to a baseline of slow pace, the hazard ratio for stroke was 0.65 (95% confidence interval, 0.44-0.97), which was fully mediated by time spent walking. Time spent walking was associated with reduced risk of onset of stroke in dose-response fashion, independent of walking pace. Walking could form an important part of stroke-prevention strategies in older people.

  20. Connected Traveler

    Energy Technology Data Exchange (ETDEWEB)

    2016-06-01

    The Connected Traveler framework seeks to boost the energy efficiency of personal travel and the overall transportation system by maximizing the accuracy of predicted traveler behavior in response to real-time feedback and incentives. It is anticipated that this approach will establish a feedback loop that 'learns' traveler preferences and customizes incentives to meet or exceed energy efficiency targets by empowering individual travelers with information needed to make energy-efficient choices and reducing the complexity required to validate transportation system energy savings. This handout provides an overview of NREL's Connected Traveler project, including graphics, milestones, and contact information.

  1. Use of Low-Level Sensor Data to Improve the Accuracy of Bluetooth-Based Travel Time Estimation

    DEFF Research Database (Denmark)

    Araghi, Bahar Namaki; Christensen, Lars Tørholm; Krishnan, Rajesh

    2013-01-01

    by a single device. The latter situation could lead to location ambiguity and could reduce the accuracy of travel time estimation. Therefore, the accuracy of travel time estimation by Bluetooth technology depends on how location ambiguity is handled by the estimation method. The issue of multiple detection...... events in the context of travel time estimation by Bluetooth technology has been considered by various researchers. However, treatment of this issue has been simplistic. Most previous studies have used the first detection event (enter-enter) as the best estimate. No systematic analysis has been conducted...... to explore the most accurate method of travel time estimation with multiple detection events. In this study, different aspects of the Bluetooth detection zone, including size and impact on the accuracy of travel time estimation, were discussed. Four methods were applied to estimate travel time: enter...

  2. Measurement of informal care: an empirical study into the valid measurement of time spent on informal caregiving.

    NARCIS (Netherlands)

    Berg, Bernard van den; Spauwen, Pol

    2006-01-01

    The incorporation of informal care into economic evaluations of health care is troublesome. The debate focuses on the valuation of time spent on informal caregiving, while time measurement, a related and may be even a more important issue, tends to be neglected. Valid time measurement is a necessary

  3. Commuters’ attitudes and norms related to travel time and punctuality: A psychographic segmentation to reduce congestion

    DEFF Research Database (Denmark)

    Haustein, Sonja; Thorhauge, Mikkel; Cherchi, Elisabetta

    2018-01-01

    three distinct commuter segments: (1) Unhurried timely commuters, who find it very important to arrive on time but less important to have a short travel time; (2) Self-determined commuters, who find it less important to arrive on lime and depend less on others for their transport choices; and (3) Busy...... commuters, who find it both important to arrive on time and to have a short travel time. Comparing the segments based on background variables shows that Self-determined commuters are younger and work more often on flextime, while Unhurried timely commuters have longer distances to work and commute more...... often by public transport. Results of a discrete departure time choice model, estimated based on data from a stated preference experiment, confirm the criterion validity of the segmentation. A scenario simulating a toll ring illustrates that mainly Self-determined commuters would change their departure...

  4. Time Spent With Children and Working Parents’ Willingness to Medicate ADHD-Like Behaviors

    Directory of Open Access Journals (Sweden)

    Bora Pajo

    2013-11-01

    Full Text Available How much time parents spend with their children is likely to influence their judgments of children’s behaviors and the behaviors themselves. In the diagnosis of children with attention-deficit/hyperactivity disorder (ADHD, parents are key informants and decide whether their children should receive medication. This exploratory study investigates the relationship between working parents’ willingness to medicate ADHD-like behaviors and the time they can spend with their children during a regular workday. The participants (409 parents of 5- to 17- year-old children reporting having no child with emotional or behavioral problems and 87 reporting having such a child were drawn from a population-based telephone survey of parents stratified by race and ethnicity in two urban Florida counties. Path analysis models, controlling for selected sociodemographic and household variables, showed that spending more time with one’s children during a regular workday and self-identifying as African American were negatively related to willingness to medicate among parents of children with problems. Among parents reporting no children with problems, only the number of children in the household and the parent-type household showed relationships to willingness to medicate, while mothers were more likely than fathers to spend more time with children. These observed relationships were of moderate effect but underscore the importance to initiate studies using valid measures of quantity and quality of parental time spent with ADHD children, and to query parents on these points when assessing the information they provide to clinicians.

  5. A methodology for rearranging transit stops for enhancing transit users generalized travel time

    Directory of Open Access Journals (Sweden)

    Mohammad Nurul Hassan

    2017-02-01

    Full Text Available This study develops a methodology to consolidate transit stops. It develops a mathematical model and a program which takes stop consolidation decision(s according to users generalized travel time savings and desired accessibility. The model iterates until the users generalized travel time savings are maximized. The study tests this mathematical model in different hypothetical scenarios. Six factors (distance between stops, passenger activity, average cruising speed, maximum walking distance, service frequency, and percentage of decreased passengers with multiple levels were set to build the scenarios. Three responses (percentage of consolidated stops, percentages of travel time and operating time savings were observed. The findings showed that the distance between the stops the passenger activity, and the probable demand change (or the percentage of decreased passengers are the most influential factors. The frequency of service was found to be influential as well. The average cruising speed has very little influence on the response variables. Finally, the model is tested on two routes (route 900 and 930 of Al Ain City public bus service. It shows that 22 and 32 out of 98 and 126 stops can be consolidated in route 900 and 930 respectively. This can save considerable amounts of users travel and operating times. In monetary values, the savings are about $329,827 and $491,094 per year for routes 900 and 930, respectively.

  6. Travel medicine

    Science.gov (United States)

    Aw, Brian; Boraston, Suni; Botten, David; Cherniwchan, Darin; Fazal, Hyder; Kelton, Timothy; Libman, Michael; Saldanha, Colin; Scappatura, Philip; Stowe, Brian

    2014-01-01

    Abstract Objective To define the practice of travel medicine, provide the basics of a comprehensive pretravel consultation for international travelers, and assist in identifying patients who might require referral to travel medicine professionals. Sources of information Guidelines and recommendations on travel medicine and travel-related illnesses by national and international travel health authorities were reviewed. MEDLINE and EMBASE searches for related literature were also performed. Main message Travel medicine is a highly dynamic specialty that focuses on pretravel preventive care. A comprehensive risk assessment for each individual traveler is essential in order to accurately evaluate traveler-, itinerary-, and destination-specific risks, and to advise on the most appropriate risk management interventions to promote health and prevent adverse health outcomes during travel. Vaccinations might also be required and should be personalized according to the individual traveler’s immunization history, travel itinerary, and the amount of time available before departure. Conclusion A traveler’s health and safety depends on a practitioner’s level of expertise in providing pretravel counseling and vaccinations, if required. Those who advise travelers are encouraged to be aware of the extent of this responsibility and to refer all high-risk travelers to travel medicine professionals whenever possible. PMID:25500599

  7. Monostable traveling waves for a time-periodic and delayed nonlocal reaction-diffusion equation

    Science.gov (United States)

    Li, Panxiao; Wu, Shi-Liang

    2018-04-01

    This paper is concerned with a time-periodic and delayed nonlocal reaction-diffusion population model with monostable nonlinearity. Under quasi-monotone or non-quasi-monotone assumptions, it is known that there exists a critical wave speed c_*>0 such that a periodic traveling wave exists if and only if the wave speed is above c_*. In this paper, we first prove the uniqueness of non-critical periodic traveling waves regardless of whether the model is quasi-monotone or not. Further, in the quasi-monotone case, we establish the exponential stability of non-critical periodic traveling fronts. Finally, we illustrate the main results by discussing two types of death and birth functions arising from population biology.

  8. Is the travel time of private roads too short, too long, or just right?

    NARCIS (Netherlands)

    van den Berg, V.A.C.; Verhoef, E.T.

    2012-01-01

    We consider price and service-quality setting in oligopolistic markets for congestible services, applied to the case of private roads. Previous studies show that parallel competitors set a volume/capacity ratio (and thereby a travel time or service quality) that is socially optimal if they take the

  9. Travel Time Model for Right-Turning Vehicles of Secondary Street at Unsignalized Intersections

    Directory of Open Access Journals (Sweden)

    Feng Yu-Qin

    2013-01-01

    Full Text Available The travel time of right-turning vehicles on secondary street at unsignalized intersection is discussed in this paper. Under the assumption that the major-street through vehicles’ headway follows Erlang distribution and secondary-street right-turning vehicles’ headway follows Poisson distribution. The right-turning vehicles travel time model is established on the basis of gap theory and M/G/1 queue theory. Comparison is done with the common model based on the assumption that the major-street vehicles’ headway follows Poisson distribution. An intersection is selected to verify each model. The results show that the model established in this paper has stronger applicability, and its most relative error is less than 15%. In addition, the sensitivity analysis has been done. The results show that right-turning flow rate and major-street flow rate have a significant impact on the travel time. Hence, the methodology for travel time of right-turning vehicles at unsignalized intersection proposed in this paper is effective and applicable.

  10. Assessment of Smolt Condition for Travel Time Analysis, 1993-1994 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Schrock, Robin M; Beeman, John W; VanderKooi, Scott P [US Geological Survey, Western Fisheries Research Center, Columbia River Research Laboratory, Cook, WA

    1999-02-01

    The assessment of smolt condition for travel time analysis (ASCTTA) project provided information on the level of smoltification in Columbia River hatchery and wild salmonid stocks to the Fish Passage Center (FPC), for the primary purpose of in-river management of flows.

  11. Estimating Reaction Rate Coefficients Within a Travel-Time Modeling Framework

    Energy Technology Data Exchange (ETDEWEB)

    Gong, R [Georgia Institute of Technology; Lu, C [Georgia Institute of Technology; Luo, Jian [Georgia Institute of Technology; Wu, Wei-min [Stanford University; Cheng, H. [Stanford University; Criddle, Craig [Stanford University; Kitanidis, Peter K. [Stanford University; Gu, Baohua [ORNL; Watson, David B [ORNL; Jardine, Philip M [ORNL; Brooks, Scott C [ORNL

    2011-03-01

    A generalized, efficient, and practical approach based on the travel-time modeling framework is developed to estimate in situ reaction rate coefficients for groundwater remediation in heterogeneous aquifers. The required information for this approach can be obtained by conducting tracer tests with injection of a mixture of conservative and reactive tracers and measurements of both breakthrough curves (BTCs). The conservative BTC is used to infer the travel-time distribution from the injection point to the observation point. For advection-dominant reactive transport with well-mixed reactive species and a constant travel-time distribution, the reactive BTC is obtained by integrating the solutions to advective-reactive transport over the entire travel-time distribution, and then is used in optimization to determine the in situ reaction rate coefficients. By directly working on the conservative and reactive BTCs, this approach avoids costly aquifer characterization and improves the estimation for transport in heterogeneous aquifers which may not be sufficiently described by traditional mechanistic transport models with constant transport parameters. Simplified schemes are proposed for reactive transport with zero-, first-, nth-order, and Michaelis-Menten reactions. The proposed approach is validated by a reactive transport case in a two-dimensional synthetic heterogeneous aquifer and a field-scale bioremediation experiment conducted at Oak Ridge, Tennessee. The field application indicates that ethanol degradation for U(VI)-bioremediation is better approximated by zero-order reaction kinetics than first-order reaction kinetics.

  12. Obtaining local reflectivity at two-way travel time by filtering acoustic reflection data

    NARCIS (Netherlands)

    Slob, E.C.; Zhang, L.; Wapenaar, C.P.A.; Mihai Popovici, A.; Fomel, S.

    2017-01-01

    A modified implementation of Marchenko redatuming leads to a filter that removes internal multiples from reflection data. It produces local reflectivity at two-way travel time. The method creates new primary reflections resulting from emitted events that eliminate internal multiples. We call these

  13. Involuntary Mental Time Travel and Its Effect on Prospective Teachers' Situational Intrinsic Motivations

    Science.gov (United States)

    Eren, Altay

    2010-01-01

    Recent cognitive psychological research has argued that involuntary mental time travel is an important individual difference variable that has the potential to affect an individual's motivation. However, this issue has not been empirically investigated in educational settings such as teacher education. Therefore, this study aimed to explore the…

  14. Modeling Travel Time Reliability of Road Network Considering Connected Vehicle Guidance Characteristics Indexes

    Directory of Open Access Journals (Sweden)

    Jiangfeng Wang

    2017-01-01

    Full Text Available Travel time reliability (TTR is one of the important indexes for effectively evaluating the performance of road network, and TTR can effectively be improved using the real-time traffic guidance information. Compared with traditional traffic guidance, connected vehicle (CV guidance can provide travelers with more timely and accurate travel information, which can further improve the travel efficiency of road network. Five CV characteristics indexes are selected as explanatory variables including the Congestion Level (CL, Penetration Rate (PR, Compliance Rate (CR, release Delay Time (DT, and Following Rate (FR. Based on the five explanatory variables, a TTR model is proposed using the multilogistic regression method, and the prediction accuracy and the impact of characteristics indexes on TTR are analyzed using a CV guidance scenario. The simulation results indicate that 80% of the RMSE is concentrated within the interval of 0 to 0.0412. The correlation analysis of characteristics indexes shows that the influence of CL, PR, CR, and DT on the TTR is significant. PR and CR have a positive effect on TTR, and the average improvement rate is about 77.03% and 73.20% with the increase of PR and CR, respectively, while CL and DT have a negative effect on TTR, and TTR decreases by 31.21% with the increase of DT from 0 to 180 s.

  15. Analyzing the effects of geological and parameter uncertainty on prediction of groundwater head and travel time

    DEFF Research Database (Denmark)

    He, X.; Sonneborg, T.O.; Jørgensen, F.

    2013-01-01

    in three scenarios involving simulation of groundwater head distribution and travel time. The first scenario implied 100 stochastic geological models all assigning the same hydraulic parameters for the same geological units. In the second scenario the same 100 geological models were subjected to model...

  16. The effect of centralization of health care services on travel time and its equality.

    Science.gov (United States)

    Kobayashi, Daisuke; Otsubo, Tetsuya; Imanaka, Yuichi

    2015-03-01

    To analyze the regional variations in travel time between patient residences and medical facilities for the treatment of ischemic heart disease and breast cancer, and to simulate the effects of health care services centralization on travel time and equality of access. We used medical insurance claims data for inpatients and outpatients for the two target diseases that had been filed between September 2008 and May 2009 in Kyoto Prefecture, Japan. Using a geographical information system, patient travel times were calculated based on the driving distance between patient residences and hospitals via highways and toll roads. Locations of residences and hospital locations were identified using postal codes. We then conducted a simulation analysis of centralization of health care services to designated regional core hospitals. The simulated changes in potential spatial access to care were examined. Inequalities in access to care were examined using Gini coefficients, which ranged from 0.4109 to 0.4574. Simulations of health care services centralization showed reduced travel time for most patients and overall improvements in equality of access, except in breast cancer outpatients. Our findings may contribute to the decision-making process in policies aimed at improving the potential spatial access to health care services. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  17. Parsimonious wave-equation travel-time inversion for refraction waves

    KAUST Repository

    Fu, Lei; Hanafy, Sherif M.; Schuster, Gerard T.

    2017-01-01

    We present a parsimonious wave-equation travel-time inversion technique for refraction waves. A dense virtual refraction dataset can be generated from just two reciprocal shot gathers for the sources at the endpoints of the survey line, with N

  18. Compensation for the distortion in satellite laser range predictions due to varying pulse travel times

    Science.gov (United States)

    Paunonen, Matti

    1993-01-01

    A method for compensating for the effect of the varying travel time of a transmitted laser pulse to a satellite is described. The 'observed minus predicted' range differences then appear to be linear, which makes data screening or use in range gating more effective.

  19. Fire behavior simulation in Mediterranean forests using the minimum travel time algorithm

    Science.gov (United States)

    Kostas Kalabokidis; Palaiologos Palaiologou; Mark A. Finney

    2014-01-01

    Recent large wildfires in Greece exemplify the need for pre-fire burn probability assessment and possible landscape fire flow estimation to enhance fire planning and resource allocation. The Minimum Travel Time (MTT) algorithm, incorporated as FlamMap's version five module, provide valuable fire behavior functions, while enabling multi-core utilization for the...

  20. Molecular detection of Plasmodium knowlesi in a Dutch traveler by real-time PCR.

    Science.gov (United States)

    Link, Lonneke; Bart, Aldert; Verhaar, Nienke; van Gool, Tom; Pronk, Marjolijn; Scharnhorst, Volkher

    2012-07-01

    Plasmodium knowlesi infection with low parasitemia presents a diagnostic challenge, as rapid diagnostic tests are often negative and identification to the species level by microscopy is difficult. P. knowlesi malaria in a traveler is described, and real-time PCR is demonstrated to support fast and reliable diagnosis and identification to the species level.

  1. Psychological, interpersonal, and clinical factors predicting time spent on physical activity among Mexican patients with hypertension

    Directory of Open Access Journals (Sweden)

    Ybarra Sagarduy JL

    2018-01-01

    Full Text Available José Luis Ybarra Sagarduy,1 Dacia Yurima Camacho Mata,1 José Moral de la Rubia,2 Julio Alfonso Piña López,3 José Luis Masud Yunes Zárraga4 1Unit of Social Work and Human Development, Autonomous University of Tamaulipas, Ciudad Victoria, 2School of Psychology, Autonomous University of Nuevo Leon, Monterrey, 3Independent Researcher, Hermosillo, 4Institute of Health and Safety Services for State Workers, Clinic for the Study and Prevention of the Chilhood Obesity, Ciudad Victoria, Mexico Background: It is widely known that physical activity is the key to the optimal management and clinical control of hypertension.Purpose: This research was conducted to identify factors that can predict the time spent on physical activity among Mexican adults with hypertension.Methods: This cross-sectional study was conducted among 182 Mexican patients with hypertension, who completed a set of self-administered questionnaires related to personality, social support, and medical adherence and health care behaviors, body mass index, and time since the disease diagnosis. Several path analyses were performed in order to test the predictors of the study behavior.Results: Lower tolerance to frustration, more tolerance to ambiguity, more effective social support, and less time since the disease diagnosis predicted more time spent on physical activity, accounting for 13.3% of the total variance. The final model shows a good fit to the sample data (pBS =0.235, χ2/gl =1.519, Jöreskog and Sörbom’s Goodness of Fit Index =0.987, adjusted modality =0.962, Bollen’s Incremental Fit Index =0.981, Bentler-Bonett Normed Fit Index =0.946, standardized root mean square residual =0.053.Conclusion: The performance of physical activity in patients with hypertension depends on a complex set of interactions between personal, interpersonal, and clinical variables. Understanding how these factors interact might enhance the design of interdisciplinary intervention programs so

  2. The nitrate response of a lowland catchment and groundwater travel times

    Science.gov (United States)

    van der Velde, Ype; Rozemeijer, Joachim; de Rooij, Gerrit; van Geer, Frans

    2010-05-01

    Intensive agriculture in lowland catchments causes eutrophication of downstream waters. To determine effective measures to reduce the nutrient loads from upstream lowland catchments, we need to understand the origin of long-term and daily variations in surface water nutrient concentrations. Surface water concentrations are often linked to travel time distributions of water passing through the saturated and unsaturated soil of the contributing catchment. This distribution represents the contact time over which sorption, desorption and degradation takes place. However, travel time distributions are strongly influenced by processes like tube drain flow, overland flow and the dynamics of draining ditches and streams and therefore exhibit strong daily and seasonal variations. The study we will present is situated in the 6.6 km2 Hupsel brook catchment in The Netherlands. In this catchment nitrate and chloride concentrations have been intensively monitored for the past 26 years under steadily decreasing agricultural inputs. We described the complicated dynamics of subsurface water fluxes as streams, ditches and tube drains locally switch between active or passive depending on the ambient groundwater level by a groundwater model with high spatial and temporal resolutions. A transient particle tracking approach is used to derive a unique catchment-scale travel time distribution for each day during the 26 year model period. These transient travel time distributions are not smooth distributions, but distributions that are strongly spiked reflecting the contribution of past rainfall events to the current discharge. We will show that a catchment-scale mass response function approach that only describes catchment-scale mixing and degradation suffices to accurately reproduce observed chloride and nitrate surface water concentrations as long as the mass response functions include the dynamics of travel time distributions caused by the highly variable connectivity of the surface

  3. Travelling wave solutions for some time-delayed equations through factorizations

    International Nuclear Information System (INIS)

    Fahmy, E.S.

    2008-01-01

    In this work, we use factorization method to find explicit particular travelling wave solutions for the following important nonlinear second-order partial differential equations: The generalized time-delayed Burgers-Huxley, time-delayed convective Fishers, and the generalized time-delayed Burgers-Fisher. Using the particular solutions for these equations we find the general solutions, two-parameter solution, as special cases

  4. Viruses as groundwater tracers: using ecohydrology to characterize short travel times in aquifers

    Science.gov (United States)

    Hunt, Randall J.; Borchardt, Mark A.; Bradbury, Kenneth R.

    2014-01-01

    Viruses are attractive tracers of short (population over time; therefore, the virus snapshot shed in the fecal wastes of an infected population at a specific point in time can serve as a marker for tracking virus and groundwater movement. The virus tracing approach and an example application are described to illustrate their ability to characterize travel times in high-groundwater velocity settings, and provide insight unavailable from standard hydrogeologic approaches. Although characterization of preferential flowpaths does not usually characterize the majority of other travel times occurring in the groundwater system (e.g., center of plume mass; tail of the breakthrough curve), virus approaches can trace very short times of transport, and thus can fill an important gap in our current hydrogeology toolbox.

  5. Negotiating on location, timing, duration, and participant in agent-mediated joint activity-travel scheduling

    Science.gov (United States)

    Ma, Huiye; Ronald, Nicole; Arentze, Theo A.; Timmermans, Harry J. P.

    2013-10-01

    Agent-based simulation has become an important modeling approach in activity-travel analysis. Social activities account for a large amount of travel and have an important effect on activity-travel scheduling. Participants in joint activities usually have various options regarding location, participants, and timing and take different approaches to make their decisions. In this context, joint activity participation requires negotiation among agents involved, so that conflicts among the agents can be addressed. Existing mechanisms do not fully provide a solution when utility functions of agents are nonlinear and non-monotonic. Considering activity-travel scheduling in time and space as an application, we propose a novel negotiation approach, which takes into account these properties, such as continuous and discrete issues, and nonlinear and non-monotonic utility functions, by defining a concession strategy and a search mechanism. The results of experiments show that agents having these properties can negotiate efficiently. Furthermore, the negotiation procedure affects individuals’ choices of location, timing, duration, and participants.

  6. Efficient data analysis and travel time picking methods for crosshole GPR experiments

    DEFF Research Database (Denmark)

    Keskinen, Johanna; Moreau, Julien; Nielsen, Lars

    2013-01-01

    to the source position, and the vertical axis to the travel time. Using OpendTect (dGB Earth Sciences), this data cube is then displayed and inspected in a 3D environment, which allows for effective and efficient data analysis. Quality control and data editing of the individual transmitter gathers can be rapidly......-attribute analyses. We believe that this approach to 3D representation and analysis of GPR crosshole data greatly improves consistency in travel time picking and reduces the time needed for the picking process. Moreover, the approach is well suited for generation of high quality input data for tomographic inversion...... methods. Future time-lapse GPR studies of different types of chalk aim at characterizing the flow characteristics of these economically important lithologies. In the framework of the current study, we have collected new crosshole GPR data from a site located in a former quarry in Eastern Denmark, where...

  7. Interactive, open source, travel time scenario modelling: tools to facilitate participation in health service access analysis.

    Science.gov (United States)

    Fisher, Rohan; Lassa, Jonatan

    2017-04-18

    Modelling travel time to services has become a common public health tool for planning service provision but the usefulness of these analyses is constrained by the availability of accurate input data and limitations inherent in the assumptions and parameterisation. This is particularly an issue in the developing world where access to basic data is limited and travel is often complex and multi-modal. Improving the accuracy and relevance in this context requires greater accessibility to, and flexibility in, travel time modelling tools to facilitate the incorporation of local knowledge and the rapid exploration of multiple travel scenarios. The aim of this work was to develop simple open source, adaptable, interactive travel time modelling tools to allow greater access to and participation in service access analysis. Described are three interconnected applications designed to reduce some of the barriers to the more wide-spread use of GIS analysis of service access and allow for complex spatial and temporal variations in service availability. These applications are an open source GIS tool-kit and two geo-simulation models. The development of these tools was guided by health service issues from a developing world context but they present a general approach to enabling greater access to and flexibility in health access modelling. The tools demonstrate a method that substantially simplifies the process for conducting travel time assessments and demonstrate a dynamic, interactive approach in an open source GIS format. In addition this paper provides examples from empirical experience where these tools have informed better policy and planning. Travel and health service access is complex and cannot be reduced to a few static modeled outputs. The approaches described in this paper use a unique set of tools to explore this complexity, promote discussion and build understanding with the goal of producing better planning outcomes. The accessible, flexible, interactive and

  8. Time spent with friends in adolescence relates to less neural sensitivity to later peer rejection.

    Science.gov (United States)

    Masten, Carrie L; Telzer, Eva H; Fuligni, Andrew J; Lieberman, Matthew D; Eisenberger, Naomi I

    2012-01-01

    Involvement with friends carries many advantages for adolescents, including protection from the detrimental effects of being rejected by peers. However, little is known about the mechanisms through which friendships may serve their protective role at this age, or the potential benefit of these friendships as adolescents transition to adulthood. As such, this investigation tested whether friend involvement during adolescence related to less neural sensitivity to social threats during young adulthood. Twenty-one adolescents reported the amount of time they spent with friends outside of school using a daily diary. Two years later they underwent an fMRI scan, during which they were ostensibly excluded from an online ball-tossing game by two same-age peers. Findings from region of interest and whole brain analyses revealed that spending more time with friends during adolescence related to less activity in the dorsal anterior cingulate cortex and anterior insula--regions previously linked with negative affect and pain processing--during an experience of peer rejection 2 years later. These findings are consistent with the notion that positive relationships during adolescence may relate to individuals being less sensitive to negative social experiences later on.

  9. Robotic Spent Fuel Monitoring – It is time to improve old approaches and old techniques!

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, Stephen Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dasari, Venkateswara Rao [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Trellue, Holly Renee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-12-13

    This report describes various approaches and techniques associated with robotic spent fuel monitoring. The purpose of this description is to improve the quality of measured signatures, reduce the inspection burden on the IAEA, and to provide frequent verification.

  10. Grey Literature Searching for Health Sciences Systematic Reviews: A Prospective Study of Time Spent and Resources Utilized.

    Science.gov (United States)

    Saleh, Ahlam A; Ratajeski, Melissa A; Bertolet, Marnie

    To identify estimates of time taken to search grey literature in support of health sciences systematic reviews and to identify searcher or systematic review characteristics that may impact resource selection or time spent searching. A survey was electronically distributed to searchers embarking on a new systematic review. Characteristics of the searcher and systematic review were collected along with time spent searching and what resources were searched. Time and resources were tabulated and resources were categorized as grey or non-grey. Data was analyzed using Kruskal-Wallis tests. Out of 81 original respondents, 21% followed through with completion of the surveys in their entirety. The median time spent searching all resources was 471 minutes, and of those a median of 85 minutes were spent searching grey literature. The median number of resources used in a systematic review search was four and the median number of grey literature sources searched was two. The amount of time spent searching was influenced by whether the systematic review was grant funded. Additionally, the number of resources searched was impacted by institution type and whether systematic review training was received. This study characterized the amount of time for conducting systematic review searches including searching the grey literature, in addition to the number and types of resources used. This may aid searchers in planning their time, along with providing benchmark information for future studies. This paper contributes by quantifying current grey literature search patterns and associating them with searcher and review characteristics. Further discussion and research into the search approach for grey literature in support of systematic reviews is encouraged.

  11. Travel time on arterials and rural highways : state-of-the-practice synthesis on rural data collection technology.

    Science.gov (United States)

    2013-04-01

    "Travel time to a destination is a key piece of information that motorists want and need, and is vital for good decision-making by travelers. Technology now makes it feasible to provide drivers with real-time information about how long it takes to re...

  12. Urban Freight Management with Stochastic Time-Dependent Travel Times and Application to Large-Scale Transportation Networks

    Directory of Open Access Journals (Sweden)

    Shichao Sun

    2015-01-01

    Full Text Available This paper addressed the vehicle routing problem (VRP in large-scale urban transportation networks with stochastic time-dependent (STD travel times. The subproblem which is how to find the optimal path connecting any pair of customer nodes in a STD network was solved through a robust approach without requiring the probability distributions of link travel times. Based on that, the proposed STD-VRP model can be converted into solving a normal time-dependent VRP (TD-VRP, and algorithms for such TD-VRPs can also be introduced to obtain the solution. Numerical experiments were conducted to address STD-VRPTW of practical sizes on a real world urban network, demonstrated here on the road network of Shenzhen, China. The stochastic time-dependent link travel times of the network were calibrated by historical floating car data. A route construction algorithm was applied to solve the STD problem in 4 delivery scenarios efficiently. The computational results showed that the proposed STD-VRPTW model can improve the level of customer service by satisfying the time-window constraint under any circumstances. The improvement can be very significant especially for large-scale network delivery tasks with no more increase in cost and environmental impacts.

  13. Water Travel Time Distributions in Permafrost-affected Catchments: Challenges, Progress and Implications

    Science.gov (United States)

    Smith, A. A.; Piovano, T. I.; Tetzlaff, D.; Ala-aho, P. O. A.; Wookey, P. A.; Soulsby, C.

    2017-12-01

    Characterising the travel times of water has been a major research focus in catchment science over the past decade. Use of isotopes to quantify the temporal dynamics of the transformation of precipitation into runoff has revealed fundamental new insights into catchment flow paths and mixing processes that influence biogeochemical transport. However, permafrost-affected catchments have received little attention, despite their global importance in terms of rapid environmental change. Such places have limited access for data collection during critical periods (e.g. early phases of snowmelt), temporal and spatially variable freeze-thaw cycles, and the development of the active layer has a time variant influence on catchment hydrology. All of these characteristics make the application of traditional transit time estimation approaches challenging. This contribution describes an isotope-based study undertaken to provide a preliminary assessment of travel times at SikSik Creek in the Canadian Arctic. We adopted a model-data fusion approach to estimate the volumes and isotopic characteristics of snowpack and meltwater. Using sampling in the spring/summer we characterise the isotopic composition of summer rainfall, melt from residual snow, soil water and stream water. In addition, soil moisture dynamics and the temporal evolution of the active layer profile were also monitored. Transit times were estimated for soil and stream water compositions using lumped convolution integral models and temporally variable inputs including snowmelt, ice thaw, and summer rainfall. Comparing transit time estimates using a variety of inputs reveals transit time is best estimated using all available inflows (i.e. snowmelt, ice thaw, and rainfall). Early spring transit times are short, dominated by snowmelt and ice thaw and limited catchment storage when soils are predominantly frozen. However, significant and increasing mixing with water in the active layer during the summer results in more

  14. Efficient Constraint Handling in Electromagnetism-Like Algorithm for Traveling Salesman Problem with Time Windows

    Science.gov (United States)

    Yurtkuran, Alkın

    2014-01-01

    The traveling salesman problem with time windows (TSPTW) is a variant of the traveling salesman problem in which each customer should be visited within a given time window. In this paper, we propose an electromagnetism-like algorithm (EMA) that uses a new constraint handling technique to minimize the travel cost in TSPTW problems. The EMA utilizes the attraction-repulsion mechanism between charged particles in a multidimensional space for global optimization. This paper investigates the problem-specific constraint handling capability of the EMA framework using a new variable bounding strategy, in which real-coded particle's boundary constraints associated with the corresponding time windows of customers, is introduced and combined with the penalty approach to eliminate infeasibilities regarding time window violations. The performance of the proposed algorithm and the effectiveness of the constraint handling technique have been studied extensively, comparing it to that of state-of-the-art metaheuristics using several sets of benchmark problems reported in the literature. The results of the numerical experiments show that the EMA generates feasible and near-optimal results within shorter computational times compared to the test algorithms. PMID:24723834

  15. Efficient Constraint Handling in Electromagnetism-Like Algorithm for Traveling Salesman Problem with Time Windows

    Directory of Open Access Journals (Sweden)

    Alkın Yurtkuran

    2014-01-01

    Full Text Available The traveling salesman problem with time windows (TSPTW is a variant of the traveling salesman problem in which each customer should be visited within a given time window. In this paper, we propose an electromagnetism-like algorithm (EMA that uses a new constraint handling technique to minimize the travel cost in TSPTW problems. The EMA utilizes the attraction-repulsion mechanism between charged particles in a multidimensional space for global optimization. This paper investigates the problem-specific constraint handling capability of the EMA framework using a new variable bounding strategy, in which real-coded particle’s boundary constraints associated with the corresponding time windows of customers, is introduced and combined with the penalty approach to eliminate infeasibilities regarding time window violations. The performance of the proposed algorithm and the effectiveness of the constraint handling technique have been studied extensively, comparing it to that of state-of-the-art metaheuristics using several sets of benchmark problems reported in the literature. The results of the numerical experiments show that the EMA generates feasible and near-optimal results within shorter computational times compared to the test algorithms.

  16. DETERMINANT FACTORS OF TIME SPENT ON FACEBOOK: BRAND COMMUNITY ENGAGEMENT AND USAGE TYPES

    OpenAIRE

    ULUSU, Yard. Doç. Dr. Yeşim

    2010-01-01

    Online  social  networks  have  integrated  into  the  computer  mediated  communication  (CMC) environment  in  the  past  few  years.  Social  Networks  such  as  Facebook,  Myspace,  Bebo  and  Twitter  are  web‐based services that allow people to create a public profile, share the connection with other users, and view and traverse  their  list  of  connections  in  common  network.  The  aim  of  this  study  is  to  find  factors  affecting  the amount  of  time  users  spent  on  Facebo...

  17. Teen worker safety training: methods used, lessons taught, and time spent.

    Science.gov (United States)

    Zierold, Kristina M

    2015-05-01

    Safety training is strongly endorsed as one way to prevent teens from performing dangerous tasks at work. The objective of this mixed methods study was to characterize the safety training that teenagers receive on the job. From 2010 through 2012, focus groups and a cross-sectional survey were conducted with working teens. The top methods of safety training reported were safety videos (42 percent) and safety lectures (25 percent). The top lessons reported by teens were "how to do my job" and "ways to spot hazards." Males, who were more likely to do dangerous tasks, received less safety training than females. Although most teens are getting safety training, it is inadequate. Lessons addressing safety behaviors are missing, training methods used are minimal, and the time spent is insignificant. More research is needed to understand what training methods and lessons should be used, and the appropriate safety training length for effectively preventing injury in working teens. In addition, more research evaluating the impact of high-quality safety training compared to poor safety training is needed to determine the best training programs for teens. © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  18. Energy beyond food: foraging theory informs time spent in thermals by a large soaring bird.

    Directory of Open Access Journals (Sweden)

    Emily L C Shepard

    Full Text Available Current understanding of how animals search for and exploit food resources is based on microeconomic models. Although widely used to examine feeding, such constructs should inform other energy-harvesting situations where theoretical assumptions are met. In fact, some animals extract non-food forms of energy from the environment, such as birds that soar in updraughts. This study examined whether the gains in potential energy (altitude followed efficiency-maximising predictions in the world's heaviest soaring bird, the Andean condor (Vultur gryphus. Animal-attached technology was used to record condor flight paths in three-dimensions. Tracks showed that time spent in patchy thermals was broadly consistent with a strategy to maximise the rate of potential energy gain. However, the rate of climb just prior to leaving a thermal increased with thermal strength and exit altitude. This suggests higher rates of energetic gain may not be advantageous where the resulting gain in altitude would lead to a reduction in the ability to search the ground for food. Consequently, soaring behaviour appeared to be modulated by the need to reconcile differing potential energy and food energy distributions. We suggest that foraging constructs may provide insight into the exploitation of non-food energy forms, and that non-food energy distributions may be more important in informing patterns of movement and residency over a range of scales than previously considered.

  19. Estimating the Value of Life, Injury, and Travel Time Saved Using a Stated Preference Framework.

    Science.gov (United States)

    Niroomand, Naghmeh; Jenkins, Glenn P

    2016-06-01

    The incidence of fatality over the period 2010-2014 from automobile accidents in North Cyprus is 2.75 times greater than the average for the EU. With the prospect of North Cyprus entering the EU, many investments will need to be undertaken to improve road safety in order to reach EU benchmarks. The objective of this study is to provide local estimates of the value of a statistical life and injury along with the value of time savings. These are among the parameter values needed for the evaluation of the change in the expected incidence of automotive accidents and time savings brought about by such projects. In this study we conducted a stated choice experiment to identify the preferences and tradeoffs of automobile drivers in North Cyprus for improved travel times, travel costs, and safety. The choice of route was examined using mixed logit models to obtain the marginal utilities associated with each attribute of the routes that consumers choose. These estimates were used to assess the individuals' willingness to pay (WTP) to avoid fatalities and injuries and to save travel time. We then used the results to obtain community-wide estimates of the value of a statistical life (VSL) saved, the value of injury (VI) prevented, and the value per hour of travel time saved. The estimates for the VSL range from €315,293 to €1,117,856 and the estimates of VI from € 5,603 to € 28,186. These values are consistent, after adjusting for differences in incomes, with the median results of similar studies done for EU countries. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. 41 CFR 301-71.306 - Are there exceptions to collecting an advance at the time the employee files a travel claim?

    Science.gov (United States)

    2010-07-01

    ... collecting an advance at the time the employee files a travel claim? 301-71.306 Section 301-71.306 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES...-71.306 Are there exceptions to collecting an advance at the time the employee files a travel claim...

  1. Time's up. descriptive epidemiology of multi-morbidity and time spent on health related activity by older Australians: a time use survey.

    Directory of Open Access Journals (Sweden)

    Tanisha Jowsey

    Full Text Available Most Western health systems remain single illness orientated despite the growing prevalence of multi-morbidity. Identifying how much time people with multiple chronic conditions spend managing their health will help policy makers and health service providers make decisions about areas of patient need for support. This article presents findings from an Australian study concerning the time spent on health related activity by older adults (aged 50 years and over, most of whom had multiple chronic conditions. A recall questionnaire was developed, piloted, and adjusted. Sampling was undertaken through three bodies; the Lung Foundation Australia (COPD sub-sample, National Diabetes Services Scheme (Diabetes sub-sample and National Seniors Australia (Seniors sub-sample. Questionnaires were mailed out during 2011 to 10,600 older adults living in Australia. 2540 survey responses were received and analysed. Descriptive analyses were completed to obtain median values for the hours spent on each activity per month. The mean number of chronic conditions was 3.7 in the COPD sub-sample, 3.4 in the Diabetes sub-sample and 2.0 in the NSA sub-sample. The study identified a clear trend of increased time use associated with increased number of chronic conditions. Median monthly time use was 5-16 hours per month overall for our three sub-samples. For respondents in the top decile with five or more chronic conditions the median time use was equivalent to two to three hours per day, and if exercise is included in the calculations, respondents spent from between five and eight hours per day: an amount similar to full-time work. Multi-morbidity imposes considerable time burdens on patients. Ageing is associated with increasing rates of multi-morbidity. Many older adults are facing high demands on their time to manage their health in the face of decreasing energy and mobility. Their time use must be considered in health service delivery and health system reform.

  2. Determinants of Children's Use of and Time Spent in Fast-Food and Full-Service Restaurants

    Science.gov (United States)

    McIntosh, Alex; Kubena, Karen S.; Tolle, Glen; Dean, Wesley; Kim, Mi-Jeong; Jan, Jie-Sheng; Anding, Jenna

    2011-01-01

    Objective: Identify parental and children's determinants of children's use of and time spent in fast-food (FF) and full-service (FS) restaurants. Design: Analysis of cross-sectional data. Setting: Parents were interviewed by phone; children were interviewed in their homes. Participants: Parents and children ages 9-11 or 13-15 from 312 families…

  3. Associations between Parental and Friend Social Support and Children’s Physical Activity and Time Spent outside Playing

    Directory of Open Access Journals (Sweden)

    Constantinos A. Loucaides

    2017-01-01

    Full Text Available The purpose of this study was to examine the structural validity of a parent and a child questionnaire that assessed parental and friends’ influences on children’s physical activity and investigate the associations between the derived factors, physical activity, and time spent outside. Children (N=154, mean age = 11.7 and 144 of their parents completed questionnaires assessing parental and friends’ influences on children’s physical activity. Children wore a pedometer for six days. Exploratory factor analyses revealed four factors for the parental and five for the child’s questionnaire that explained 66.71% and 63.85% of the variance, respectively. Five factors were significantly associated with physical activity and five significantly associated with time spent outside. Higher correlations were revealed between “general friend support,” “friends’ activity norms,” and physical activity (r=0.343 and 0.333 resp., p<0.001 and between “general friend support” and time spent outside (r=0.460, p<0.001. Obtaining information relating to parental and friends’ influences on physical activity from both parents and children may provide a more complete picture of influences. Parents and friends seem to influence children’s physical activity behavior and time spent outside, but friends’ influences may have a stronger impact on children’s behaviors.

  4. Is time spent playing video games associated with mental health, cognitive and social skills in young children?

    NARCIS (Netherlands)

    Kovess-Masfety, V.; Keyes, K.M.; Hamilton, A.; Hanson, G.; Bitfoi, A.; Golitz, D.; Koç, C.; Kuijpers, R.C.W.M.; Lesinskiene, S.; Mihova, Z.; Otten, R.; Fermanian, C.; Pez, O.

    2016-01-01

    Video games are one of the favourite leisure activities of children; the influence on child health is usually perceived to be negative. The present study assessed the association between the amount of time spent playing video games and children mental health as well as cognitive and social skills.

  5. Efficient evaluation of shortest travel-time path queries through spatial mashups

    KAUST Repository

    Zhang, Detian; Chow, Chi-Yin; Liu, An; Zhang, Xiangliang; Ding, Qingzhu; Li, Qing

    2017-01-01

    In the real world, the route/path with the shortest travel time in a road network is more meaningful than that with the shortest network distance for location-based services (LBS). However, not every LBS provider has adequate resources to compute/estimate travel time for routes by themselves. A cost-effective way for LBS providers to estimate travel time for routes is to issue external route requests to Web mapping services (e.g., Google Maps, Bing Maps, and MapQuest Maps). Due to the high cost of processing such external route requests and the usage limits of Web mapping services, we take the advantage of direction sharing, parallel requesting and waypoints supported by Web mapping services to reduce the number of external route requests and the query response time for shortest travel-time route queries in this paper. We first give the definition of sharing ability to reflect the possibility of sharing the direction information of a route with others, and find out the queries that their query routes are independent with each other for parallel processing. Then, we model the problem of selecting the optimal waypoints for an external route request as finding the longest simple path in a weighted complete digraph. As it is a MAX SNP-hard problem, we propose a greedy algorithm with performance guarantee to find the best set of waypoints in an external route request. We evaluate the performance of our approach using a real Web mapping service, a real road network, real and synthetic data sets. Experimental results show the efficiency, scalability, and applicability of our approach.

  6. Efficient evaluation of shortest travel-time path queries through spatial mashups

    KAUST Repository

    Zhang, Detian

    2017-01-07

    In the real world, the route/path with the shortest travel time in a road network is more meaningful than that with the shortest network distance for location-based services (LBS). However, not every LBS provider has adequate resources to compute/estimate travel time for routes by themselves. A cost-effective way for LBS providers to estimate travel time for routes is to issue external route requests to Web mapping services (e.g., Google Maps, Bing Maps, and MapQuest Maps). Due to the high cost of processing such external route requests and the usage limits of Web mapping services, we take the advantage of direction sharing, parallel requesting and waypoints supported by Web mapping services to reduce the number of external route requests and the query response time for shortest travel-time route queries in this paper. We first give the definition of sharing ability to reflect the possibility of sharing the direction information of a route with others, and find out the queries that their query routes are independent with each other for parallel processing. Then, we model the problem of selecting the optimal waypoints for an external route request as finding the longest simple path in a weighted complete digraph. As it is a MAX SNP-hard problem, we propose a greedy algorithm with performance guarantee to find the best set of waypoints in an external route request. We evaluate the performance of our approach using a real Web mapping service, a real road network, real and synthetic data sets. Experimental results show the efficiency, scalability, and applicability of our approach.

  7. Time of travel of solutes in Buffalo Bayou and selected tributaries, Houston, Texas, August 1999

    Science.gov (United States)

    East, Jeffery W.; Schaer, Jasper D.

    2000-01-01

    The U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency, conducted a time-of-travel study in the Buffalo Bayou watershed during low flow in August 1999. The study was done as part of the U.S. Environmental Protection Agency Environmental Monitoring for Public Access and Community Tracking (EMPACT) program. The EMPACT program was designed for the U.S. Environmental Protection Agency to work with communities to “make timely, accurate, and understandable environmental information available to millions of people in the largest metropolitan areas across the country.” (U.S. Environmental Protection Agency, 2000). Buffalo Bayou, located in Houston, Texas, was chosen as a pilot project because it is a frequently used recreational water source, it has many water-treatment facilities located along its stream segments, and it has a history of water-quality problems (Houston-Galveston Area Council, 2000). One component of the pilot project is to develop a water-quality simulation model that can be used to assess the effects of noncompliance events on Buffalo Bayou. Because accurate estimates of time of travel during low flow are required to develop the model, the time of travel of solutes in Buffalo Bayou and selected tributaries was determined using dye tracing methods. The study was conducted during low flow in a 38.7-mile reach of Buffalo Bayou, a 9.6-mile reach of Whiteoak Bayou, a 5.9-mile reach of Mason Creek, and a 6.6-mile reach of Bear Creek. Efforts to determine the time of travel in a 7.5-mile reach of Horsepen Creek were unsuccessful. This report explains the approach used to conduct the study and presents the results of the study

  8. Maternal Time Use and Nurturing: Analysis of the Association Between Breastfeeding Practice and Time Spent Interacting with Baby.

    Science.gov (United States)

    Smith, Julie P; Forrester, Robert

    2017-06-01

    Breastfeeding supports child development through complex mechanisms that are not well understood. Numerous studies have compared how well breastfeeding and nonbreastfeeding mothers interact with their child, but few examine how much interaction occurs. Our study of weekly time use among 156 mothers of infants aged 3-9 months investigated whether lactating mothers spend more time providing emotional support or cognitive stimulation of their infants than nonbreastfeeding mothers, and whether the amount of such interactive time is associated with breastfeeding intensity. Mothers were recruited via mother's and baby groups, infant health clinics, and childcare services, and used an electronic device to record their 24-hour time use for 7 days. Sociodemographic and feeding status data were collected by questionnaire. Statistical analysis using linear mixed modeling and residual maximum likelihood analysis compared maternal time use for those giving "some breastfeeding" and those "not breastfeeding." Analysis was also conducted for more detailed feeding subgroups. Breastfeeding and nonbreastfeeding mothers had broadly similar socioeconomic and demographic characteristics. Breastfeeding was found to be associated with more mother-child interaction time, a difference only partially explained by weekly maternal employment hours or other interactive care activities such as play or reading. This study presents data suggesting that lactating mothers spent significantly more hours weekly on milk feeding and on carrying, holding, or soothing their infant than nonlactating mothers; and on providing childcare. Understanding the mechanisms by which child mental health and development benefits from breastfeeding may have important implications for policies and intervention strategies, and could be usefully informed by suitably designed time use studies.

  9. Stability of Intelligent Transportation Network Dynamics: A Daily Path Flow Adjustment considering Travel Time Differentiation

    Directory of Open Access Journals (Sweden)

    Ming-Chorng Hwang

    2015-01-01

    Full Text Available A theoretic formulation on how traffic time information distributed by ITS operations influences the trajectory of network flows is presented in this paper. The interactions between users and ITS operator are decomposed into three parts: (i travel time induced path flow dynamics (PFDTT; (ii demand induced path flow dynamics (PFDD; and (iii predicted travel time dynamics for an origin-destination (OD pair (PTTDOD. PFDTT describes the collective results of user’s daily route selection by pairwise comparison of path travel time provided by ITS services. The other two components, PTTDOD and PFDD, are concentrated on the evolutions of system variables which are predicted and observed, respectively, by ITS operators to act as a benchmark in guiding the target system towards an expected status faster. In addition to the delivered modelings, the stability theorem of the equilibrium solution in the sense of Lyapunov stability is also provided. A Lyapunov function is developed and employed to the proof of stability theorem to show the asymptotic behavior of the aimed system. The information of network flow dynamics plays a key role in traffic control policy-making. The evaluation of ITS-based strategies will not be reasonable without a well-established modeling of network flow evolutions.

  10. Transport device of spent fuel

    International Nuclear Information System (INIS)

    Watanabe, Takashi.

    1976-01-01

    Object: To provide a transport device of spent fuel particularly used in a fast breeder, which can enhance accessibility to travelling mechanism portions and exchangeability thereof to facilitate maintenance in the event of failure. Structure: On a travelling floor, which has a function to shield radioactive rays, extending in a direction of transporting spent fuel and being formed with a break passing through in a direction wall thickness, a travelling body is moved along the break. The travelling body has a support rod member mounted thereon, and the support rod member is moved within the break, the support rod member having a fuel support pocket suspended therefrom. (Furukawa, Y.)

  11. Ranking of septic tank and drainfield sites using travel time to the groundwater table

    International Nuclear Information System (INIS)

    Langkopf, B.S.; McCord, J.T.

    1994-09-01

    The Environmental Restoration Program at Sandia National Laboratories, New Mexico (SNL/NM) is tasked with performing assessments and cleanup of waste sites that belong to SNL. SNL's waste sites are divided into several activities. Septic Tanks and Drainfields (STD) is an activity that includes 23 different sites at SNL/NM. All these sites may have released hazardous wastes into the soil from drains or sewers of buildings. The STD sites must be assessed and, if necessary, remediated according to the Resource Conservation and Recovery Act (RCRA) Corrective Action process. A modeling study has been completed to help prioritize the sites for future field investigation based on the risk that each site may pose to human health and the environment. Two of the influences on the risk to human health and environment are addressed in this study--the fluid disposal volume and groundwater depth. These two parameters, as well as several others, were used as input into a computer model to calculate groundwater travel time to the water table. The computer model was based on Darcy's Law and a simple mass balance. To account for uncertainty in the input parameters, a Monte Carlo approach was used to determine the travel times; 1,000 realizations were completed to determine the travel time for each site. The range assigned to each of the input parameters was sampled according to an assigned statistical distribution using the Latin Hypercube Method to arrive at input for the calculations. The groundwater travel times resulting from these calculations were used to rank the sites for future field investigation

  12. [Travel time and participation in breast cancer screening in a region with high population dispersion].

    Science.gov (United States)

    Borda, Alfredo; Sanz, Belén; Otero, Laura; Blasco, Teresa; García-Gómez, Francisco J; de Andrés, Fuencisla

    2011-01-01

    To analyze the association between travel time and participation in a breast cancer screening program adjusted for contextual variables in the province of Segovia (Spain). We performed an ecological study using the following data sources: the Breast Cancer Early Detection Program of the Primary Care Management of Segovia, the Population and Housing Census for 2001 and the municipal register for 2006-2007. The study period comprised January 2006 to December 2007. Dependent variables consisted of the municipal participation rate and the desired level of municipal participation (greater than or equal to 70%). The key independent variable was travel time from the municipality to the mammography unit. Covariables consisted of the municipalities' demographic and socioeconomic factors. We performed univariate and multivariate Poisson regression analyses of the participation rate, and logistic regression of the desired participation level. The sample was composed of 178 municipalities. The mean participation rate was 75.2%. The desired level of participation (≥ 70%) was achieved in 119 municipalities (67%). In the multivariate Poisson and logistic regression analyses, longer travel time was associated with a lower participation rate and with lower participation after adjustment was made for geographic density, age, socioeconomic status and dependency ratio, with a relative risk index of 0.88 (95% CI: 0.81-0.96) and an odds ratio of 0.22 (95% CI: 0.1-0.47), respectively. Travel time to the mammography unit may help to explain participation in breast cancer screening programs. Copyright © 2010 SESPAS. Published by Elsevier Espana. All rights reserved.

  13. Travel Time Estimation Using Freeway Point Detector Data Based on Evolving Fuzzy Neural Inference System.

    Science.gov (United States)

    Tang, Jinjun; Zou, Yajie; Ash, John; Zhang, Shen; Liu, Fang; Wang, Yinhai

    2016-01-01

    Travel time is an important measurement used to evaluate the extent of congestion within road networks. This paper presents a new method to estimate the travel time based on an evolving fuzzy neural inference system. The input variables in the system are traffic flow data (volume, occupancy, and speed) collected from loop detectors located at points both upstream and downstream of a given link, and the output variable is the link travel time. A first order Takagi-Sugeno fuzzy rule set is used to complete the inference. For training the evolving fuzzy neural network (EFNN), two learning processes are proposed: (1) a K-means method is employed to partition input samples into different clusters, and a Gaussian fuzzy membership function is designed for each cluster to measure the membership degree of samples to the cluster centers. As the number of input samples increases, the cluster centers are modified and membership functions are also updated; (2) a weighted recursive least squares estimator is used to optimize the parameters of the linear functions in the Takagi-Sugeno type fuzzy rules. Testing datasets consisting of actual and simulated data are used to test the proposed method. Three common criteria including mean absolute error (MAE), root mean square error (RMSE), and mean absolute relative error (MARE) are utilized to evaluate the estimation performance. Estimation results demonstrate the accuracy and effectiveness of the EFNN method through comparison with existing methods including: multiple linear regression (MLR), instantaneous model (IM), linear model (LM), neural network (NN), and cumulative plots (CP).

  14. Seismic Travel Time Tomography in Modeling Low Velocity Anomalies between the Boreholes

    Science.gov (United States)

    Octova, A.; Sule, R.

    2018-04-01

    Travel time cross-hole seismic tomography is applied to describing the structure of the subsurface. The sources are placed at one borehole and some receivers are placed in the others. First arrival travel time data that received by each receiver is used as the input data in seismic tomography method. This research is devided into three steps. The first step is reconstructing the synthetic model based on field parameters. Field parameters are divided into 24 receivers and 45 receivers. The second step is applying inversion process for the field data that consists of five pairs bore holes. The last step is testing quality of tomogram with resolution test. Data processing using FAST software produces an explicit shape and resemble the initial model reconstruction of synthetic model with 45 receivers. The tomography processing in field data indicates cavities in several place between the bore holes. Cavities are identified on BH2A-BH1, BH4A-BH2A and BH4A-BH5 with elongated and rounded structure. In resolution tests using a checker-board, anomalies still can be identified up to 2 meter x 2 meter size. Travel time cross-hole seismic tomography analysis proves this mothod is very good to describing subsurface structure and boundary layer. Size and anomalies position can be recognized and interpreted easily.

  15. Chinese and Australians showed difference in mental time travel in emotion and content but not specificity

    Directory of Open Access Journals (Sweden)

    Xing-jie eChen

    2015-06-01

    Full Text Available Mental time travel refers to the ability to recall episodic past and imagine future events. The present study aimed to investigate cultural differences in mental time travel between Chinese and Australian university students. A total of 231 students (108 Chinese & 123 Australians participated in the study. Their mental time travel abilities were measured by the Sentence Completion for Events from the Past Test (SCEPT and the Sentence Completion for Events in the Future Test (SCEFT. Results showed that there were no cultural differences in the number of specific events generated for the past or future. Significant differences between the Chinese and Australian participants were found mainly in the emotional valence and content of the events generated. Both Chinese and Australian participants generated more specific positive events compared to negative events when thinking about the future and Chinese participants were more positive about their past than Australian participants when recalled specific events. For content, Chinese participants recalled more events about their interpersonal relationships, while Australian participants imagined more about personal future achievements. These findings shed some lights on cultural differences in episodic past and future thinking.

  16. Deficits in episodic memory and mental time travel in patients with post-traumatic stress disorder.

    Science.gov (United States)

    Zlomuzica, Armin; Woud, Marcella L; Machulska, Alla; Kleimt, Katharina; Dietrich, Lisa; Wolf, Oliver T; Assion, Hans-Joerg; Huston, Joseph P; De Souza Silva, Maria A; Dere, Ekrem; Margraf, Jürgen

    2018-04-20

    Post-traumatic stress disorder (PTSD) is characterized by impairments in mnestic functions, especially in the domain of episodic memory. These alterations might affect different aspects of episodic memory functioning. Here we tested PTSD patients and healthy controls (matched for age, sex and education) in a newly developed virtual reality episodic memory test (VR-EMT), a test for mental time travel, episodic future thinking, and prospective memory (M3xT). In a cross-validation experiment, their performance was further evaluated in the Rivermead Behavioral Memory Test (RBMT). PTSD patients demonstrated impairments in episodic memory formation and mental time travel and showed difficulties in utilizing information from episodic memory to solve problems. Diminished attention and concentration in PTSD did not account for performance deficits in these tasks but higher levels of negative arousal were found in PTSD patients. Furthermore, performance in the VR-EMT and RBMT in PTSD patients correlated negatively with self-reported measures of stress and depression. Our results suggest that deficits in episodic memory formation and mental time travel in PTSD lead to difficulties in utilizing the content of episodic memories for solving problems in the present or to plan future behavior. Clinical implications of these findings and suggestions for cognitive-behavioral treatment of PTSD are discussed. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Travel-time source-specific station correction improves location accuracy

    Science.gov (United States)

    Giuntini, Alessandra; Materni, Valerio; Chiappini, Stefano; Carluccio, Roberto; Console, Rodolfo; Chiappini, Massimo

    2013-04-01

    Accurate earthquake locations are crucial for investigating seismogenic processes, as well as for applications like verifying compliance to the Comprehensive Test Ban Treaty (CTBT). Earthquake location accuracy is related to the degree of knowledge about the 3-D structure of seismic wave velocity in the Earth. It is well known that modeling errors of calculated travel times may have the effect of shifting the computed epicenters far from the real locations by a distance even larger than the size of the statistical error ellipses, regardless of the accuracy in picking seismic phase arrivals. The consequences of large mislocations of seismic events in the context of the CTBT verification is particularly critical in order to trigger a possible On Site Inspection (OSI). In fact, the Treaty establishes that an OSI area cannot be larger than 1000 km2, and its larger linear dimension cannot be larger than 50 km. Moreover, depth accuracy is crucial for the application of the depth event screening criterion. In the present study, we develop a method of source-specific travel times corrections based on a set of well located events recorded by dense national seismic networks in seismically active regions. The applications concern seismic sequences recorded in Japan, Iran and Italy. We show that mislocations of the order of 10-20 km affecting the epicenters, as well as larger mislocations in hypocentral depths, calculated from a global seismic network and using the standard IASPEI91 travel times can be effectively removed by applying source-specific station corrections.

  18. Travel time to maternity care and its effect on utilization in rural Ghana: a multilevel analysis.

    Science.gov (United States)

    Masters, Samuel H; Burstein, Roy; Amofah, George; Abaogye, Patrick; Kumar, Santosh; Hanlon, Michael

    2013-09-01

    Rates of neonatal and maternal mortality are high in Ghana. In-facility delivery and other maternal services could reduce this burden, yet utilization rates of key maternal services are relatively low, especially in rural areas. We tested a theoretical implication that travel time negatively affects the use of in-facility delivery and other maternal services. Empirically, we used geospatial techniques to estimate travel times between populations and health facilities. To account for uncertainty in Ghana Demographic and Health Survey cluster locations, we adopted a novel approach of treating the location selection as an imputation problem. We estimated a multilevel random-intercept logistic regression model. For rural households, we found that travel time had a significant effect on the likelihood of in-facility delivery and antenatal care visits, holding constant education, wealth, maternal age, facility capacity, female autonomy, and the season of birth. In contrast, a facility's capacity to provide sophisticated maternity care had no detectable effect on utilization. As the Ghanaian health network expands, our results suggest that increasing the availability of basic obstetric services and improving transport infrastructure may be important interventions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. The effect of the development of an emergency transfer system on the travel time to tertiary care centres in Japan

    Directory of Open Access Journals (Sweden)

    Arima Hideaki

    2006-06-01

    Full Text Available Abstract Background In Japan, the emergency medical system is categorized into three levels: primary, secondary, and tertiary, depending on the severity of the condition of the patient. Tertiary care centres accept patients who require 24-h monitoring. In this research, the average travel times (minutes from the centroids of all municipalities in Japan to the nearest tertiary care centre were estimated, using the geographic information system. The systems affecting travel time to tertiary care centres were also examined. Regression analysis was performed to determine the factors affecting the travel time to tertiary care centres, using selected variables representing road conditions and the emergency transfer system. Linear regression analysis was performed to identify specific benchmarks that would be effective in reducing the average travel time to tertiary care centres in prefectures with travel times longer than the average 57 min. Results The mean travel time was 57 min, the range was 83 min, and the standard deviation was 20.4. As a result of multiple regression analysis, average coverage area per tertiary care centre, kilometres of highway road per square kilometre, and population were selected as variables with impact on the average travel time. Based on results from linear regression analysis, benchmarks for the emergency transfer system that would effectively reduce travel time to the mean value of 57 min were identified: 26% pavement ratio of roads (percentage of paved road to general roads, and three tertiary care centres and 108 ambulances. Conclusion Regional gaps in the travel time to tertiary care centres were identified in Japan. The systems we should focus on to reducing travel time were identified. Further reduction of travel time to tertiary care centres can be effectively achieved by improving these specific systems. Linear regression analysis showed that a 26% pavement ratio and three tertiary care centres are beneficial to

  20. Characterizing Global Flood Wave Travel Times to Optimize the Utility of Near Real-Time Satellite Remote Sensing Products

    Science.gov (United States)

    Allen, G. H.; David, C. H.; Andreadis, K. M.; Emery, C. M.; Famiglietti, J. S.

    2017-12-01

    Earth observing satellites provide valuable near real-time (NRT) information about flood occurrence and magnitude worldwide. This NRT information can be used in early flood warning systems and other flood management applications to save lives and mitigate flood damage. However, these NRT products are only useful to early flood warning systems if they are quickly made available, with sufficient time for flood mitigation actions to be implemented. More specifically, NRT data latency, or the time period between the satellite observation and when the user has access to the information, must be less than the time it takes a flood to travel from the flood observation location to a given downstream point of interest. Yet the paradigm that "lower latency is always better" may not necessarily hold true in river systems due to tradeoffs between data latency and data quality. Further, the existence of statistical breaks in the global distribution of flood wave travel time (i.e. a jagged statistical distribution) would represent preferable latencies for river-observation NRT remote sensing products. Here we present a global analysis of flood wave velocity (i.e. flow celerity) and travel time. We apply a simple kinematic wave model to a global hydrography dataset and calculate flow wave celerity and travel time during bankfull flow conditions. Bankfull flow corresponds to the condition of maximum celerity and thus we present the "worst-case scenario" minimum flow wave travel time. We conduct a similar analysis with respect to the time it takes flood waves to reach the next downstream city, as well as the next downstream reservoir. Finally, we conduct these same analyses, but with regards to the technical capabilities of the planned Surface Water and Ocean Topography (SWOT) satellite mission, which is anticipated to provide waterbody elevation and extent measurements at an unprecedented spatial and temporal resolution. We validate these results with discharge records from paired

  1. Speedometer app videos to provide real-world velocity-time graph data 1: rail travel

    Science.gov (United States)

    King, Julien

    2018-03-01

    The use of modern rail travel as a source of real-life velocity-time data to aid in the teaching of velocity and acceleration is discussed. A technique for using GPS speedometer apps to produce videos of velocity and time figures during a rail journey is described. The technique is applied to a UK rail journey, demonstrating how students can use its results to produce a velocity-time graph from which acceleration and deceleration figures can be calculated. These are compared with theoretical maximum figures, calculated from the train’s technical specification.

  2. Value of travel-time reliability : commuters' route-choice behavior in the Twin Cities, phase 2.

    Science.gov (United States)

    2012-04-01

    Travel-time variability is a noteworthy factor in network performance. It measures the temporal uncertainty : experienced by users in their movement between any two nodes in a network. The importance : of the time variance depends on the penalties in...

  3. 41 CFR 302-3.512 - How many times are we required to pay for an employee's return travel?

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 4 2010-07-01 2010-07-01 false How many times are we required to pay for an employee's return travel? 302-3.512 Section 302-3.512 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES RELOCATION ALLOWANCES 3-RELOCATION...

  4. The impact of the use of intraoperative radiotherapy on costs, travel time and distance for women with breast cancer in the Mexico City Metropolitan Area.

    Science.gov (United States)

    Bargallo-Rocha, Juan Enrique; Soto-Perez-de-Celis, Enrique; Picó-Guzmán, Francisco Javier; Quintero-Rodríguez, Carlos Eduardo; Almog, David; Santiago-Concha, Gabriel; Flores-Balcazar, Christian Haydee; Corona, Jaime; Vazquez-Romo, Rafael; Villarreal-Garza, Cynthia; Mohar, Alejandro

    2017-11-01

    The low availability and poor access to external beam radiotherapy (EBRT) in developing countries makes it hard for women with breast cancer to receive breast conservation. We studied the effect of providing intraoperative radiotherapy (IORT) on the travel time, distance, and costs of in the Mexico City Metropolitan Area (MCMA). Sixty-nine patients treated between January 2013 and September 2014 were analyzed. Travel distance and transit time was calculated using Google Maps. The time and distance patients living in the MCMA treated with IORT would have spent if they had received EBRT was calculated. Cost analysis for each modality was performed. 71% (n = 49) lived in the MCMA. Sixteen (33%) received additional EBRT and 33 (66%) received IORT only. Mean driving distance and transit time of those 33 women was 132.6 km (SD 25.7) and 66 min (SD 32.9). Patients from the MCMA receiving IORT alone avoided 990 visits, 43 700 km and 65 400 min in transit. IORT led to a 12% reduction in costs per patient. By reducing costs and time needed for patients to receive radiotherapy, IORT could potentially enhance access to breast conservation in resource-limited developing countries. © 2017 Wiley Periodicals, Inc.

  5. Sensitivity studies of unsaturated groundwater flow modeling for groundwater travel time calculations at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Altman, S.J.; Ho, C.K.; Arnold, B.W.; McKenna, S.A.

    1995-01-01

    Unsaturated flow has been modeled through four cross-sections at Yucca Mountain, Nevada, for the purpose of determining groundwater particle travel times from the potential repository to the water table. This work will be combined with the results of flow modeling in the saturated zone for the purpose of evaluating the suitability of the potential repository under the criteria of 10CFR960. One criterion states, in part, that the groundwater travel time (GWTT) from the repository to the accessible environment must exceed 1,000 years along the fastest path of likely and significant radionuclide travel. Sensitivity analyses have been conducted for one geostatistical realization of one cross-section for the purpose of (1) evaluating the importance of hydrological parameters having some uncertainty and (2) examining conceptual models of flow by altering the numerical implementation of the conceptual model (dual permeability (DK) and the equivalent continuum model (ECM). Results of comparisons of the ECM and DK model are also presented in Ho et al

  6. Predicting Flow Breakdown Probability and Duration in Stochastic Network Models: Impact on Travel Time Reliability

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Jing [ORNL; Mahmassani, Hani S. [Northwestern University, Evanston

    2011-01-01

    This paper proposes a methodology to produce random flow breakdown endogenously in a mesoscopic operational model, by capturing breakdown probability and duration. Based on previous research findings that probability of flow breakdown can be represented as a function of flow rate and the duration can be characterized by a hazard model. By generating random flow breakdown at various levels and capturing the traffic characteristics at the onset of the breakdown, the stochastic network simulation model provides a tool for evaluating travel time variability. The proposed model can be used for (1) providing reliability related traveler information; (2) designing ITS (intelligent transportation systems) strategies to improve reliability; and (3) evaluating reliability-related performance measures of the system.

  7. Travel time and attrition from VHA care among women veterans: how far is too far?

    Science.gov (United States)

    Friedman, Sarah A; Frayne, Susan M; Berg, Eric; Hamilton, Alison B; Washington, Donna L; Saechao, Fay; Maisel, Natalya C; Lin, Julia Y; Hoggatt, Katherine J; Phibbs, Ciaran S

    2015-04-01

    Travel time, an access barrier, may contribute to attrition of women veterans from Veterans Health Administration (VHA) care. We examined whether travel time influences attrition: (a) among women veterans overall, (b) among new versus established patients, and (c) among rural versus urban patients. This retrospective cohort study used logistic regression to estimate the association between drive time and attrition, overall and for new/established and rural/urban patients. In total, 266,301 women veteran VHA outpatients in the Fiscal year 2009. An "attriter" did not return for VHA care during the second through third years after her first 2009 visit (T0). Drive time (log minutes) was between the patient's residence and her regular source of VHA care. "New" patients had no VHA visits within 3 years before T0. Models included age, service-connected disability, health status, and utilization as covariates. Overall, longer drive times were associated with higher odds of attrition: drive time adjusted odds ratio=1.11 (99% confidence interval, 1.09-1.14). The relationship between drive time and attrition was stronger among new patients but was not modified by rurality. Attrition among women veterans is sensitive to longer drive time. Linking new patients to VHA services designed to reduce distance barriers (telemedicine, community-based clinics, mobile clinics) may reduce attrition among women new to VHA.

  8. Groundwater travel time uncertainty analysis. Sensitivity of results to model geometry, and correlations and cross correlations among input parameters

    International Nuclear Information System (INIS)

    Clifton, P.M.

    1985-03-01

    This study examines the sensitivity of the travel time distribution predicted by a reference case model to (1) scale of representation of the model parameters, (2) size of the model domain, (3) correlation range of log-transmissivity, and (4) cross correlations between transmissivity and effective thickness. The basis for the reference model is the preliminary stochastic travel time model previously documented by the Basalt Waste Isolation Project. Results of this study show the following. The variability of the predicted travel times can be adequately represented when the ratio between the size of the zones used to represent the model parameters and the log-transmissivity correlation range is less than about one-fifth. The size of the model domain and the types of boundary conditions can have a strong impact on the distribution of travel times. Longer log-transmissivity correlation ranges cause larger variability in the predicted travel times. Positive cross correlation between transmissivity and effective thickness causes a decrease in the travel time variability. These results demonstrate the need for a sound conceptual model prior to conducting a stochastic travel time analysis

  9. Basic Investigations of Dynamic Travel Time Estimation Model for Traffic Signals Control Using Information from Optical Beacons

    Science.gov (United States)

    Okutani, Iwao; Mitsui, Tatsuro; Nakada, Yusuke

    In this paper put forward are neuron-type models, i.e., neural network model, wavelet neuron model and three layered wavelet neuron model(WV3), for estimating traveling time between signalized intersections in order to facilitate adaptive setting of traffic signal parameters such as green time and offset. Model validation tests using simulated data reveal that compared to other models, WV3 model works very fast in learning process and can produce more accurate estimates of travel time. Also, it is exhibited that up-link information obtainable from optical beacons, i.e., travel time observed during the former cycle time in this case, makes a crucial input variable to the models in that there isn't any substantial difference between the change of estimated and simulated travel time with the change of green time or offset when up-link information is employed as input while there appears big discrepancy between them when not employed.

  10. Heart rate biofeedback fails to enhance children's ability to identify time spent in moderate to vigorous physical activity.

    Science.gov (United States)

    Conley, Marguerite M; Gastin, Paul B; Brown, Helen; Shaw, Christine

    2011-03-01

    Physical activity recommendations for children in several countries advise that all young people should accumulate at least 60 min of moderate to vigorous physical activity every day. Perceiving physical activity intensity, however, can be a difficult task for children and it is not clear whether children can identify their levels of moderate to vigorous physical activity in accordance with the recommended guidelines. This study aimed to (1) explore whether children can identify time spent in moderate to vigorous physical activity; and (2) investigate whether heart rate biofeedback would improve children's ability to estimate time spent in moderate to vigorous physical activity. Thirty seven children (15 boys and 22 girls, mean age 12.6 years) wore data recording Polar E600 heart rate monitors during eight physical education lessons. At the end of each lesson children's estimated time in zone was compared to their actual time in zone. During a six lesson Intervention phase, one class was assigned to a biofeedback group whilst the other class acted as the control group and received no heart rate biofeedback. Post-Intervention, students in the biofeedback group were no better than the control group at estimating time spent in zone (mean relative error of estimation biofeedback group: Pre-Intervention 41±32% to Post-Intervention 28±26%; control group: Pre-Intervention 40±39% to Post-Intervention 31±37%). Thus it seems that identifying time spent in moderate to vigorous physical activity remains a complex task for children aged 11-13 even with the help of heart rate biofeedback. Copyright © 2010 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  11. Impact of a University-Based Outpatient Telemedicine Program on Time Savings, Travel Costs, and Environmental Pollutants.

    Science.gov (United States)

    Dullet, Navjit W; Geraghty, Estella M; Kaufman, Taylor; Kissee, Jamie L; King, Jesse; Dharmar, Madan; Smith, Anthony C; Marcin, James P

    2017-04-01

    The objective of this study was to estimate travel-related and environmental savings resulting from the use of telemedicine for outpatient specialty consultations with a university telemedicine program. The study was designed to retrospectively analyze the telemedicine consultation database at the University of California Davis Health System (UCDHS) between July 1996 and December 2013. Travel distances and travel times were calculated between the patient home, the telemedicine clinic, and the UCDHS in-person clinic. Travel cost savings and environmental impact were calculated by determining differences in mileage reimbursement rate and emissions between those incurred in attending telemedicine appointments and those that would have been incurred if a visit to the hub site had been necessary. There were 19,246 consultations identified among 11,281 unique patients. Telemedicine visits resulted in a total travel distance savings of 5,345,602 miles, a total travel time savings of 4,708,891 minutes or 8.96 years, and a total direct travel cost savings of $2,882,056. The mean per-consultation round-trip distance savings were 278 miles, average travel time savings were 245 minutes, and average cost savings were $156. Telemedicine consultations resulted in a total emissions savings of 1969 metric tons of CO 2 , 50 metric tons of CO, 3.7 metric tons of NO x , and 5.5 metric tons of volatile organic compounds. This study demonstrates the positive impact of a health system's outpatient telemedicine program on patient travel time, patient travel costs, and environmental pollutants. Copyright © 2017 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  12. The Effects of Employment Status and Daily Stressors on Time Spent on Daily Household Chores in Middle-Aged and Older Adults

    Science.gov (United States)

    Wong, Jen D.; Almeida, David M.

    2013-01-01

    Purpose of the study: This study examines how employment status (worker vs. retiree) and life course influences (age, gender, and marital status) are associated with time spent on daily household chores. Second, this study assesses whether the associations between daily stressors and time spent on daily household chores differ as a function of…

  13. Temporal Dissociation of Neocortical and Hippocampal Contributions to Mental Time Travel Using Intracranial Recordings in Humans.

    Science.gov (United States)

    Schurr, Roey; Nitzan, Mor; Eliahou, Ruth; Spinelli, Laurent; Seeck, Margitta; Blanke, Olaf; Arzy, Shahar

    2018-01-01

    In mental time travel (MTT) one is "traveling" back-and-forth in time, remembering, and imagining events. Despite intensive research regarding memory processes in the hippocampus, it was only recently shown that the hippocampus plays an essential role in encoding the temporal order of events remembered, and therefore plays an important role in MTT. Does it also encode the temporal relations of these events to the remembering self? We asked patients undergoing pre-surgical evaluation with depth electrodes penetrating the temporal lobes bilaterally toward the hippocampus to project themselves in time to a past, future, or present time-point, and then make judgments regarding various events. Classification analysis of intracranial evoked potentials revealed clear temporal dissociation in the left hemisphere between lateral-temporal electrodes, activated at ~100-300 ms, and hippocampal electrodes, activated at ~400-600 ms. This dissociation may suggest a division of labor in the temporal lobe during self-projection in time, hinting toward the different roles of the lateral-temporal cortex and the hippocampus in MTT and the temporal organization of the related events with respect to the experiencing self.

  14. Inpatient child mortality by travel time to hospital in a rural area of Tanzania.

    Science.gov (United States)

    Manongi, Rachel; Mtei, Frank; Mtove, George; Nadjm, Behzad; Muro, Florida; Alegana, Victor; Noor, Abdisalan M; Todd, Jim; Reyburn, Hugh

    2014-05-01

    To investigate the association, if any, between child mortality and distance to the nearest hospital. The study was based on data from a 1-year study of the cause of illness in febrile paediatric admissions to a district hospital in north-east Tanzania. All villages in the catchment population were geolocated, and travel times were estimated from availability of local transport. Using bands of travel time to hospital, we compared admission rates, inpatient case fatality rates and child mortality rates in the catchment population using inpatient deaths as the numerator. Three thousand hundred and eleven children under the age of 5 years were included of whom 4.6% died; 2307 were admitted from time between admission and death. Assuming uniform mortality in the catchment population, the predicted number of deaths not benefiting from hospital admission prior to death increased by 21.4% per hour of travel time to hospital. If the same admission and death rates that were found at <3 h from the hospital applied to the whole catchment population and if hospital care conferred a 30% survival benefit compared to home care, then 10.3% of childhood deaths due to febrile illness in the catchment population would have been averted. The mortality impact of poor access to hospital care in areas of high paediatric mortality is likely to be substantial although uncertainty over the mortality benefit of inpatient care is the largest constraint in making an accurate estimate. © 2014 The Authors Tropical Medicine & International Health Published by John Wiley & Sons Ltd.

  15. High-burnup/low-cooling-time fuel carrying capacity of the GA-4 and GA-9 spent fuel shipping casks

    International Nuclear Information System (INIS)

    Boshoven, J.K.; Hopf, J.E.

    1994-01-01

    In response to utilities' projected needs to ship higher burnup spent fuel, General Atomics (GA) has performed shielding and thermal analysis for the GA-4 and GA-9 legal weight shipping casks to determine the minimum cooling times for various burnup levels for fully loaded GA-4 and GA-9 casks and reduced payloads for the casks. Tables are provided in the paper which show the minimum cooling time for a given burnup and payload for each of the casks. The analyses show that the GA-4 and GA-9 casks can carry at least as many high-burnup and/or short-cooling-time spent fuel assemblies as present day shipping casks. In addition, the GA casks are able to carry at least twice as many assemblies as the present day shipping casks if the spent fuel burnup levels and/or cooling times are open-quotes coolerclose quotes or open-quotes as coolclose quotes as their design basis fuels. The increased shipping capacity for these more common open-quotes coolerclose quotes assemblies allows fewer shipments and therefore increases the efficiency and lowers predicted risks of the transport system

  16. A method for generating an illusion of backwards time travel using immersive virtual reality-an exploratory study.

    Science.gov (United States)

    Friedman, Doron; Pizarro, Rodrigo; Or-Berkers, Keren; Neyret, Solène; Pan, Xueni; Slater, Mel

    2014-01-01

    We introduce a new method, based on immersive virtual reality (IVR), to give people the illusion of having traveled backwards through time to relive a sequence of events in which they can intervene and change history. The participant had played an important part in events with a tragic outcome-deaths of strangers-by having to choose between saving 5 people or 1. We consider whether the ability to go back through time, and intervene, to possibly avoid all deaths, has an impact on how the participant views such moral dilemmas, and also whether this experience leads to a re-evaluation of past unfortunate events in their own lives. We carried out an exploratory study where in the "Time Travel" condition 16 participants relived these events three times, seeing incarnations of their past selves carrying out the actions that they had previously carried out. In a "Repetition" condition another 16 participants replayed the same situation three times, without any notion of time travel. Our results suggest that those in the Time Travel condition did achieve an illusion of "time travel" provided that they also experienced an illusion of presence in the virtual environment, body ownership, and agency over the virtual body that substituted their own. Time travel produced an increase in guilt feelings about the events that had occurred, and an increase in support of utilitarian behavior as the solution to the moral dilemma. Time travel also produced an increase in implicit morality as judged by an implicit association test. The time travel illusion was associated with a reduction of regret associated with bad decisions in their own lives. The results show that when participants have a third action that they can take to solve the moral dilemma (that does not immediately involve choosing between the 1 and the 5) then they tend to take this option, even though it is useless in solving the dilemma, and actually results in the deaths of a greater number.

  17. New Applications of Cosmogenic Radioactive Isotopes to Study Water Travel Times

    Science.gov (United States)

    Visser, A.; Thaw, M.; Deinhart, A.; Bibby, R. K.; Esser, B.

    2017-12-01

    The travel time of water moving through a landscape influences nutrient dynamics and biogeochemical cycles. Constraining water travel times helps to understand the functioning of the critical zone. Water travel times cannot be observed directly but can be constrained by measurements of cosmogenic radioactive isotopes. We studied a small (4.6 km2) subalpine (1660-2117 m) catchment in a Mediterranean climate (8 °C, 1200 mm/yr) in the California Sierra Nevada to assess subsurface water storage dynamics and investigate flow paths and flow velocities. We analyzed a combination of three cosmogenic radioactive isotopes with half-lives varying from 87 days (sulfur-35), 2.6 years (sodium-22) to 12.3 years (tritium) in precipitation and stream samples. Water stable isotopes and solute chemistry aided the interpretation of the cosmogenic isotopes. Tritium samples (1L) are analyzed by noble gas mass spectrometry after helium-3 accumulation. Samples for sulfur-35 and sodium-22 are collected by processing 20-1000 L of water through an anion and cation exchange column in-situ. Sulfur-35 is analyzed by liquid scintillation counting after chemical purification and precipitation. Sodium-22 is analyzed by gamma counting after eluting the cations into a 4L Marinelli beaker. Monthly collected precipitation samples show variability of deposition rate for tritium and sulfur-35. Sodium-22 levels in cumulative yearly precipitation samples are consistent with recent studies in the US and Japan. The observed variability of deposition rates complicates direct use as decaying age tracers. The level and variability of tritium in monthly stream samples indicate a mean residence time on the order of 10 years and only small contributions of younger water during high flow conditions. Sulfur-35 and sodium-22 concentrations were critically interpreted considering possible uptake by vegetation and cation exchange. Detections of sodium-22 confirm a small fraction of younger (water. Low concentrations

  18. Expression for time travel based on diffusive wave theory: applicability and considerations

    Science.gov (United States)

    Aguilera, J. C.; Escauriaza, C. R.; Passalacqua, P.; Gironas, J. A.

    2017-12-01

    Prediction of hydrological response is of utmost importance when dealing with urban planning, risk assessment, or water resources management issues. With the advent of climate change, special care must be taken with respect to variations in rainfall and runoff due to rising temperature averages. Nowadays, while typical workstations have adequate power to run distributed routing hydrological models, it is still not enough for modeling on-the-fly, a crucial ability in a natural disaster context, where rapid decisions must be made. Semi-distributed time travel models, which compute a watershed's hydrograph without explicitly solving the full shallow water equations, appear as an attractive approach to rainfall-runoff modeling since, like fully distributed models, also superimpose a grid on the watershed, and compute runoff based on cell parameter values. These models are heavily dependent on the travel time expression for an individual cell. Many models make use of expressions based on kinematic wave theory, which is not applicable in cases where watershed storage is important, such as mild slopes. This work presents a new expression for concentration times in overland flow, based on diffusive wave theory, which considers not only the effects of storage but also the effects on upstream contribution. Setting upstream contribution equal to zero gives an expression consistent with previous work on diffusive wave theory; on the other hand, neglecting storage effects (i.e.: diffusion,) is shown to be equivalent to kinematic wave theory, currently used in many spatially distributed time travel models. The newly found expression is shown to be dependent on plane discretization, particularly when dealing with very non-kinematic cases. This is shown to be the result of upstream contribution, which gets larger downstream, versus plane length. This result also provides some light on the limits on applicability of the expression: when a certain kinematic threshold is reached, the

  19. Associations between Parental and Friend Social Support and Children’s Physical Activity and Time Spent outside Playing

    OpenAIRE

    Constantinos A. Loucaides; Niki Tsangaridou

    2017-01-01

    The purpose of this study was to examine the structural validity of a parent and a child questionnaire that assessed parental and friends' influences on children's physical activity and investigate the associations between the derived factors, physical activity, and time spent outside. Children (N = 154, mean age = 11.7) and 144 of their parents completed questionnaires assessing parental and friends' influences on children's physical activity. Children wore a pedometer for six days. Explorat...

  20. Comparison of the Amount of Time Spent on Computer Games and Aggressive Behavior in Male Middle School Students of Tehran

    OpenAIRE

    Mehrangiz Shoaa Kazemi; Zahra Shahabinezhad

    2016-01-01

    Background and Objectives: Modern technologies have a prominent role in adolescent's daily life. These technologies include specific cultural and moral patterns, which could be highly effective on adolescents. This research aimed at comparing the amount of time spent on computer games and aggressive behavior in male middle school students of Tehran. Materials and Methods: This study had a descriptive design. The study population included all male students of middle school of Tehran, and th...

  1. An assessment of travel time for spills management - using HEC-RAS water quality analysis

    Energy Technology Data Exchange (ETDEWEB)

    Disley, Tom; Gharabaghi, Bahram; Perdikaris, John [University of Guelph, Guelph, (Canada); Singh, Amanjot; Dougherty, Jennifer [Credit Valley Conservation Authority, Mississauga, (Canada)

    2010-07-01

    In order to mitigate the detrimental effects that contaminants such as petrochemical and chemical spills may have on the environment it is critical to understand their transport. This paper presented an assessment of travel time for spills management using HEC-RAS water quality analysis on the Credit River Watershed. It is a 1000 km2 area of urban and rural landscapes drained by 90 km of the main Credit River. The study focused on the mixing characteristics of 5 stream reaches in the Credit River watershed. Dye tracing was done under three different flow conditions to obtain a longitudinal dispersion coefficient, which is a necessary parameter for predicting and modelling time concentration curves downstream of a spill. The longitudinal dispersion coefficient was input into the US Army Corp of Engineers, Hydrologic Engineering Centers River Analysis System (HEC RAS) to predict time concentration curves. The HEC RAS model produced average travel time close to those measured in the field after final calibration was completed.

  2. Retrieval-travel-time model for free-fall-flow-rack automated storage and retrieval system

    Science.gov (United States)

    Metahri, Dhiyaeddine; Hachemi, Khalid

    2018-03-01

    Automated storage and retrieval systems (AS/RSs) are material handling systems that are frequently used in manufacturing and distribution centers. The modelling of the retrieval-travel time of an AS/RS (expected product delivery time) is practically important, because it allows us to evaluate and improve the system throughput. The free-fall-flow-rack AS/RS has emerged as a new technology for drug distribution. This system is a new variation of flow-rack AS/RS that uses an operator or a single machine for storage operations, and uses a combination between the free-fall movement and a transport conveyor for retrieval operations. The main contribution of this paper is to develop an analytical model of the expected retrieval-travel time for the free-fall flow-rack under a dedicated storage assignment policy. The proposed model, which is based on a continuous approach, is compared for accuracy, via simulation, with discrete model. The obtained results show that the maximum deviation between the continuous model and the simulation is less than 5%, which shows the accuracy of our model to estimate the retrieval time. The analytical model is useful to optimise the dimensions of the rack, assess the system throughput, and evaluate different storage policies.

  3. An assessment of travel time for spills management - using HEC-RAS water quality analysis

    International Nuclear Information System (INIS)

    Disley, Tom; Gharabaghi, Bahram; Perdikaris, John; Singh, Amanjot; Dougherty, Jennifer

    2010-01-01

    In order to mitigate the detrimental effects that contaminants such as petrochemical and chemical spills may have on the environment it is critical to understand their transport. This paper presented an assessment of travel time for spills management using HEC-RAS water quality analysis on the Credit River Watershed. It is a 1000 km2 area of urban and rural landscapes drained by 90 km of the main Credit River. The study focused on the mixing characteristics of 5 stream reaches in the Credit River watershed. Dye tracing was done under three different flow conditions to obtain a longitudinal dispersion coefficient, which is a necessary parameter for predicting and modelling time concentration curves downstream of a spill. The longitudinal dispersion coefficient was input into the US Army Corp of Engineers, Hydrologic Engineering Centers River Analysis System (HEC RAS) to predict time concentration curves. The HEC RAS model produced average travel time close to those measured in the field after final calibration was completed.

  4. Travel Time Estimation Using Freeway Point Detector Data Based on Evolving Fuzzy Neural Inference System.

    Directory of Open Access Journals (Sweden)

    Jinjun Tang

    Full Text Available Travel time is an important measurement used to evaluate the extent of congestion within road networks. This paper presents a new method to estimate the travel time based on an evolving fuzzy neural inference system. The input variables in the system are traffic flow data (volume, occupancy, and speed collected from loop detectors located at points both upstream and downstream of a given link, and the output variable is the link travel time. A first order Takagi-Sugeno fuzzy rule set is used to complete the inference. For training the evolving fuzzy neural network (EFNN, two learning processes are proposed: (1 a K-means method is employed to partition input samples into different clusters, and a Gaussian fuzzy membership function is designed for each cluster to measure the membership degree of samples to the cluster centers. As the number of input samples increases, the cluster centers are modified and membership functions are also updated; (2 a weighted recursive least squares estimator is used to optimize the parameters of the linear functions in the Takagi-Sugeno type fuzzy rules. Testing datasets consisting of actual and simulated data are used to test the proposed method. Three common criteria including mean absolute error (MAE, root mean square error (RMSE, and mean absolute relative error (MARE are utilized to evaluate the estimation performance. Estimation results demonstrate the accuracy and effectiveness of the EFNN method through comparison with existing methods including: multiple linear regression (MLR, instantaneous model (IM, linear model (LM, neural network (NN, and cumulative plots (CP.

  5. Travel time tomography with local image regularization by sparsity constrained dictionary learning

    Science.gov (United States)

    Bianco, M.; Gerstoft, P.

    2017-12-01

    We propose a regularization approach for 2D seismic travel time tomography which models small rectangular groups of slowness pixels, within an overall or `global' slowness image, as sparse linear combinations of atoms from a dictionary. The groups of slowness pixels are referred to as patches and a dictionary corresponds to a collection of functions or `atoms' describing the slowness in each patch. These functions could for example be wavelets.The patch regularization is incorporated into the global slowness image. The global image models the broad features, while the local patch images incorporate prior information from the dictionary. Further, high resolution slowness within patches is permitted if the travel times from the global estimates support it. The proposed approach is formulated as an algorithm, which is repeated until convergence is achieved: 1) From travel times, find the global slowness image with a minimum energy constraint on the pixel variance relative to a reference. 2) Find the patch level solutions to fit the global estimate as a sparse linear combination of dictionary atoms.3) Update the reference as the weighted average of the patch level solutions.This approach relies on the redundancy of the patches in the seismic image. Redundancy means that the patches are repetitions of a finite number of patterns, which are described by the dictionary atoms. Redundancy in the earth's structure was demonstrated in previous works in seismics where dictionaries of wavelet functions regularized inversion. We further exploit redundancy of the patches by using dictionary learning algorithms, a form of unsupervised machine learning, to estimate optimal dictionaries from the data in parallel with the inversion. We demonstrate our approach on densely, but irregularly sampled synthetic seismic images.

  6. Effect of percolation rate on water-travel time in deep, partially saturated zones

    International Nuclear Information System (INIS)

    Peters, R.R.; Gauthier, J.H.; Dudley, A.L.

    1986-02-01

    The Nevada Nuclear Waste Storage Investigations (NNWSI) project is investigating Yucca Mountain, Nye county, Nevada, as a prospective site for a radioactive-waste repository. The Yucca Mountain site is unique among those currently being investigated by the US Department of Energy (DOE) in that the prospective repository location is in the unsaturated zone, approximately 300 m above the water table. The rock units at Yucca Mountain can be grouped into three types: (1) vitric tuffs with high matrix conductivity and few fractures; (2) zeolitized tuffs with low matrix conductivity and few fractures; and (3) densely welded tuffs with low matrix conductivities and many fractures. The prospective repository zone is in densely welded tuff; the units between it and the water table are of types 1 and 2. Current percolation rates through Yucca Mountain, and those that are currently postulated under future climatic conditions, are thought to be of the order of the saturated matrix conductivity of some of the units. Although it is probable that there is now little or no water movement in fracture, it is necessary to investigate the potential for fracture flow, especially that which could be initiated under future climatic conditions. Significant fracture flow, if present, could reduce the water travel time between the repository and the water table. A composite-porosity, continuum model was developed to model flow in a fractured, porous medium. Simulations using data from the Yucca Mountain site and this model in the one-dimensional code TOSPAC indicate that current estimates of the percolation rate result in water movement confined to the matrix and that the water-travel time from the repository to the water table is on the order of hundreds of thousands of years. this result is sensitive to the percolation rate; an increase in percolation rate of a factor of 10 many initiate water movement in the fractures, reducing the travel time significantly

  7. Imaging the Mediterranean upper mantle by p- wave travel time tomography

    Directory of Open Access Journals (Sweden)

    A. Morelli

    1997-06-01

    Full Text Available Travel times of P-waves in the Euro-Mediterranean region show strong and consistent lateral variations, which can be associated to structural heterogeneity in the underlying crust and mantle. We analyze regional and tele- seismic data from the International Seismological Centre data base to construct a three-dimensional velocity model of the upper mantle. We parameterize the model by a 3D grid of nodes -with approximately 50 km spacing -with a linear interpolation law, which constitutes a three-dimensional continuous representation of P-wave velocity. We construct summary travel time residuals between pairs of cells of the Earth's surface, both inside our study area and -with a broader spacing -on the whole globe. We account for lower mantle heterogeneity outside the modeled region by using empirical corrections to teleseismic travel times. The tomo- graphic images show generai agreement with other seismological studies of this area, with apparently higher detail attained in some locations. The signature of past and present lithospheric subduction, connected to Euro- African convergence, is a prominent feature. Active subduction under the Tyrrhenian and Hellenic arcs is clearly imaged as high-velocity bodies spanning the whole upper mantle. A clear variation of the lithospheric structure beneath the Northem and Southern Apennines is observed, with the boundary running in correspon- dence of the Ortona-Roccamonfina tectonic lineament. The western section of the Alps appears to have better developed roots than the eastern, possibly reflecting à difference in past subduction of the Tethyan lithosphere and subsequent continental collision.

  8. Changes in time spent walking and the risk of incident dementia in older Japanese people: the Ohsaki Cohort 2006 Study.

    Science.gov (United States)

    Tomata, Yasutake; Zhang, Shu; Sugiyama, Kemmyo; Kaiho, Yu; Sugawara, Yumi; Tsuji, Ichiro

    2017-09-01

    the impact of long-term changes in physical activity during adulthood in the context of primary prevention of dementia has not been addressed previously. to study the relationship between changes in time spent walking after middle age and incident dementia in older Japanese individuals. we conducted a cohort study of 6,909 disability-free Japanese individuals aged ≥65 years who lived in Ohsaki City, Japan. In both 1994 and 2006, the individual amount of time spent walking per day was assessed using a self-reported questionnaire (dementia were retrieved from the public Long-term Care Insurance (LTCI) Database, in which participants were followed up for 5.7 years (between April 2007 and November 2012). The Cox model was used for estimating the multivariate-adjusted hazard ratios (HRs) of incident dementia. the 5.7-year incidence of dementia was 9.2%. Compared with persons who remained in the lowest category of time spent walking (dementia: the multivariate-adjusted HR (95% confidence intervals) was 0.72 (0.53 and 0.97). these results suggest that maintaining a higher level of physical activity after middle age may be a key strategy for prevention of dementia in older age. © The Author 2017. Published by Oxford University Press on behalf of the British Geriatrics Society.All rights reserved. For permissions, please email: journals.permissions@oup.com

  9. Groundwater travel time uncertainty analysis: Sensitivity of results to model geometry, and correlations and cross correlations among input parameters

    International Nuclear Information System (INIS)

    Clifton, P.M.

    1984-12-01

    The deep basalt formations beneath the Hanford Site are being investigated for the Department of Energy (DOE) to assess their suitability as a host medium for a high level nuclear waste repository. Predicted performance of the proposed repository is an important part of the investigation. One of the performance measures being used to gauge the suitability of the host medium is pre-waste-emplacement groundwater travel times to the accessible environment. Many deterministic analyses of groundwater travel times have been completed by Rockwell and other independent organizations. Recently, Rockwell has completed a preliminary stochastic analysis of groundwater travel times. This document presents analyses that show the sensitivity of the results from the previous stochastic travel time study to: (1) scale of representation of model parameters, (2) size of the model domain, (3) correlation range of log-transmissivity, and (4) cross-correlation between transmissivity and effective thickness. 40 refs., 29 figs., 6 tabs

  10. Analyses of Sea Surface Height, Bottom Pressure and Acoustic Travel Time in the Japan/East Sea

    National Research Council Canada - National Science Library

    Xu, Yongsheng

    2006-01-01

    ...) was deployed in the southwestern JES for two years, from June 1999 to July 2001. The PIESs recorded hourly vertical acoustic travel time and pressure, which are respectively good proxies of baroclinic and barotropic sea level variability...

  11. The impact of real-time and predictive traffic information on travelers' behavior on the I-4 corridor. Final report.

    Science.gov (United States)

    2003-07-01

    Real time and predicted traffic information plays a key role in the successful implementation of advanced traveler information systems (ATIS) and advance traffic management systems (ATMS). Traffic information is essentially valuable to both transport...

  12. Breast Intensity-Modulated Radiation Therapy Reduces Time Spent With Acute Dermatitis for Women of All Breast Sizes During Radiation

    International Nuclear Information System (INIS)

    Freedman, Gary M.; Li Tianyu; Nicolaou, Nicos; Chen Yan; Ma, Charlie C.-M.; Anderson, Penny R.

    2009-01-01

    Purpose: To study the time spent with radiation-induced dermatitis during a course of radiation therapy for breast cancer in women treated with conventional or intensity-modulated radiation therapy (IMRT). Methods and Materials: The study population consisted of 804 consecutive women with early-stage breast cancer treated with breast-conserving surgery and radiation from 2001 to 2006. All patients were treated with whole-breast radiation followed by a boost to the tumor bed. Whole-breast radiation consisted of conventional wedged photon tangents (n = 405) earlier in the study period and mostly of photon IMRT (n = 399) in later years. All patients had acute dermatitis graded each week of treatment. Results: The breakdown of the cases of maximum acute dermatitis by grade was as follows: 3%, Grade 0; 34%, Grade 1; 61%, Grade 2; and 2%, Grade 3. The breakdown of cases of maximum toxicity by technique was as follows: 48%, Grade 0/1, and 52%, Grade 2/3, for IMRT; and 25%, Grade 0/1, and 75%, Grade 2/3, for conventional radiation therapy (p < 0.0001). The IMRT patients spent 82% of weeks during treatment with Grade 0/1 dermatitis and 18% with Grade 2/3 dermatitis, compared with 29% and 71% of patients, respectively, treated with conventional radiation (p < 0.0001). Furthermore, the time spent with Grade 2/3 toxicity was decreased in IMRT patients with small (p = 0.0015), medium (p < 0.0001), and large (p < 0.0001) breasts. Conclusions: Breast IMRT is associated with a significant decrease both in the time spent during treatment with Grade 2/3 dermatitis and in the maximum severity of dermatitis compared with that associated with conventional radiation, regardless of breast size.

  13. Eye movements discriminate fatigue due to chronotypical factors and time spent on task--a double dissociation.

    Directory of Open Access Journals (Sweden)

    Dario Cazzoli

    Full Text Available Systematic differences in circadian rhythmicity are thought to be a substantial factor determining inter-individual differences in fatigue and cognitive performance. The synchronicity effect (when time of testing coincides with the respective circadian peak period seems to play an important role. Eye movements have been shown to be a reliable indicator of fatigue due to sleep deprivation or time spent on cognitive tasks. However, eye movements have not been used so far to investigate the circadian synchronicity effect and the resulting differences in fatigue. The aim of the present study was to assess how different oculomotor parameters in a free visual exploration task are influenced by: a fatigue due to chronotypical factors (being a 'morning type' or an 'evening type'; b fatigue due to the time spent on task. Eighteen healthy participants performed a free visual exploration task of naturalistic pictures while their eye movements were recorded. The task was performed twice, once at their optimal and once at their non-optimal time of the day. Moreover, participants rated their subjective fatigue. The non-optimal time of the day triggered a significant and stable increase in the mean visual fixation duration during the free visual exploration task for both chronotypes. The increase in the mean visual fixation duration correlated with the difference in subjectively perceived fatigue at optimal and non-optimal times of the day. Conversely, the mean saccadic speed significantly and progressively decreased throughout the duration of the task, but was not influenced by the optimal or non-optimal time of the day for both chronotypes. The results suggest that different oculomotor parameters are discriminative for fatigue due to different sources. A decrease in saccadic speed seems to reflect fatigue due to time spent on task, whereas an increase in mean fixation duration a lack of synchronicity between chronotype and time of the day.

  14. Using nonparametrics to specify a model to measure the value of travel time

    DEFF Research Database (Denmark)

    Fosgerau, Mogens

    2007-01-01

    Using a range of nonparametric methods, the paper examines the specification of a model to evaluate the willingness-to-pay (WTP) for travel time changes from binomial choice data from a simple time-cost trading experiment. The analysis favours a model with random WTP as the only source...... of randomness over a model with fixed WTP which is linear in time and cost and has an additive random error term. Results further indicate that the distribution of log WTP can be described as a sum of a linear index fixing the location of the log WTP distribution and an independent random variable representing...... unobserved heterogeneity. This formulation is useful for parametric modelling. The index indicates that the WTP varies systematically with income and other individual characteristics. The WTP varies also with the time difference presented in the experiment which is in contradiction of standard utility theory....

  15. 41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?

    Science.gov (United States)

    2010-07-01

    ... departure/arrival dates and times on my travel claim? 301-11.10 Section 301-11.10 Public Contracts and... dates and times on my travel claim? You must record the date of departure from, and arrival at, the... visited. You do not have to record departure/arrival times, but you must annotate your travel claim when...

  16. Remote sensing of temperature and wind using acoustic travel-time measurements

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Manuela; Fischer, Gabi; Raabe, Armin; Weisse, Frank [Leipzig Univ. (Germany). Inst. fuer Meteorologie; Ziemann, Astrid [Technische Univ. Dresden (Germany). Professur fuer Meteorologie

    2013-04-15

    A remote sensing technique to detect area-averaged temperature and flow properties within an area under investigation, utilizing acoustic travel-time measurements, is introduced. This technique uses the dependency of the speed of acoustic signals on the meteorological parameters temperature and wind along the propagation path. The method itself is scalable: It is applicable for investigation areas with an extent of some hundred square metres as well as for small-scale areas in the range of one square metre. Moreover, an arrangement of the acoustic transducers at several height levels makes it possible to determine profiles and gradients of the meteorological quantities. With the help of two examples the potential of this remote sensing technique for simultaneously measuring averaged temperature and flow fields is demonstrated. A comparison of time histories of temperature and wind values derived from acoustic travel-time measurements with point measurements shows a qualitative agreement whereas calculated root-mean-square errors differ for the two example applications. They amount to 1.4 K and 0.3 m/s for transducer distances of 60 m and 0.4 K and 0.2 m/s for transducer distances in the range of one metre. (orig.)

  17. Prescribed journeys through life: Cultural differences in mental time travel between Middle Easterners and Scandinavians.

    Science.gov (United States)

    Ottsen, Christina Lundsgaard; Berntsen, Dorthe

    2015-12-01

    Mental time travel is the ability to remember past events and imagine future events. Here, 124 Middle Easterners and 128 Scandinavians generated important past and future events. These different societies present a unique opportunity to examine effects of culture. Findings indicate stronger influence of normative schemas and greater use of mental time travel to teach, inform and direct behaviour in the Middle East compared with Scandinavia. The Middle Easterners generated more events that corresponded to their cultural life script and that contained religious words, whereas the Scandinavians reported events with a more positive mood impact. Effects of gender were mainly found in the Middle East. Main effects of time orientation largely replicated recent findings showing that simulation of future and past events are not necessarily parallel processes. In accordance with the notion that future simulations rely on schema-based construction, important future events showed a higher overlap with life script events than past events in both cultures. In general, cross-cultural discrepancies were larger in future compared with past events. Notably, the high focus in the Middle East on sharing future events to give cultural guidance is consistent with the increased adherence to normative scripts found in this culture. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. PolyWaTT: A polynomial water travel time estimator based on Derivative Dynamic Time Warping and Perceptually Important Points

    Science.gov (United States)

    Claure, Yuri Navarro; Matsubara, Edson Takashi; Padovani, Carlos; Prati, Ronaldo Cristiano

    2018-03-01

    Traditional methods for estimating timing parameters in hydrological science require a rigorous study of the relations of flow resistance, slope, flow regime, watershed size, water velocity, and other local variables. These studies are mostly based on empirical observations, where the timing parameter is estimated using empirically derived formulas. The application of these studies to other locations is not always direct. The locations in which equations are used should have comparable characteristics to the locations from which such equations have been derived. To overcome this barrier, in this work, we developed a data-driven approach to estimate timing parameters such as travel time. Our proposal estimates timing parameters using historical data of the location without the need of adapting or using empirical formulas from other locations. The proposal only uses one variable measured at two different locations on the same river (for instance, two river-level measurements, one upstream and the other downstream on the same river). The recorded data from each location generates two time series. Our method aligns these two time series using derivative dynamic time warping (DDTW) and perceptually important points (PIP). Using data from timing parameters, a polynomial function generalizes the data by inducing a polynomial water travel time estimator, called PolyWaTT. To evaluate the potential of our proposal, we applied PolyWaTT to three different watersheds: a floodplain ecosystem located in the part of Brazil known as Pantanal, the world's largest tropical wetland area; and the Missouri River and the Pearl River, in United States of America. We compared our proposal with empirical formulas and a data-driven state-of-the-art method. The experimental results demonstrate that PolyWaTT showed a lower mean absolute error than all other methods tested in this study, and for longer distances the mean absolute error achieved by PolyWaTT is three times smaller than empirical

  19. Providing Advanced and Real-Time Travel/Traffic Information to Tourists

    Science.gov (United States)

    1998-10-01

    Advanced traveler information systems (ATIS) analyze and communicate information that can enhance travel efficiency, alleviate congestion, and increase safety. In Texas, tourists (i.e., tripmakers unacquainted with the state) constitute an important ...

  20. Effects of spatial attention on mental time travel in patients with neglect.

    Science.gov (United States)

    Anelli, Filomena; Avanzi, Stefano; Arzy, Shahar; Mancuso, Mauro; Frassinetti, Francesca

    2018-04-01

    Numerous studies agree that time is represented in spatial terms in the brain. Here we investigate how a deficit in orienting attention in space influences the ability to mentally travel in time, that is to recall the past and anticipate the future. Right brain-damaged patients, with (RBD-N+) and without neglect (RBD-N-), and healthy controls (HC) were subjected to a Mental Time Travel (MTT) task. Participants were asked to project themselves in time to past, present or future (i.e., self-projection) and, for each self-projection, to judge whether events were located relatively in the past or the future (i.e., self-reference). The MTT-task was performed before and after a manipulation, through prismatic adaptation (PA), inducing a leftward shift of spatial attention. Before PA, RBD-N+ were slower for future than for past events, whereas RBD-N- and HC responded similarly to past and future events. A leftward shift of spatial attention by PA reduced the difference in past/future processing in RBD-N+ and fastened RBD-N- and HC's response to past events. Assuming that time concepts, such as past/future, are coded with a left-to-right order on a mental time line (MTL), a recursive search of future-events can explain neglect patients' performance. Improvement of the spatial deficit following PA reduces the recursive search of future events on the rightmost part of the MTL, facilitating exploration of past events on the leftmost part of the MTL, finally favoring the correct location of past and future events. In addition, the study of the anatomical correlates of the temporal deficit in mental time travel through voxel-based lesion-symptom mapping showed a correlation with a lesion located in the insula and in the thalamus. These findings provide new insights about the inter-relations of space and time, and can pave the way to a procedure to rehabilitate a deficit in these cognitive domains. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. THE DECISION MAKING OF BUSINESS TRAVELLERS IN SELECTING ONLINE TRAVEL PORTALS FOR TRAVEL BOOKING: AN EMPIRICAL STUDY OF DELHI NATIONAL CAPITAL REGION, INDIA

    Directory of Open Access Journals (Sweden)

    Bivek DATTA

    2018-05-01

    Full Text Available The purpose of this paper is to understand the decision making pattern of the Business Travellers in Delhi National Capital Region in India while booking their trips through Online Travel Portals. The study revolves around purchase decision pattern of Business Travellers by investigating their travel decision making style in selecting online travel portals for their trip booking. The authors have adopted the quantitative methodology to achieve the objective of the study. The study is confined purely to the Business Travellers who book their travel through online travel portals. The data was collected through a structured questionnaire. 300 Business Travellers were interviewed at the departure lounge of Indira Gandhi International Airport, New Delhi, India out of which 150 questionnaires were incomplete in many respects and could not be used and only 150 questionnaires were usable resulting in the response rate of 50%. The Analytical Hierarchy process method was adopted to analyze the relative weights assigned by Business Travellers. The present study identifies through literature review the nine fundamental values of internet purchase i.e. product quality, cost, time to receive the product, convenience, time spent, confidentiality, shopping enjoyment, security and environmental impact. The research findings indicate that business travellers value confidentiality, security and product quality the most while choosing the Online Travel Portal to book their trip. The study is primarily centered on the consumer typology approach to study the decision making patterns of business travellers whereas there are other variables such as lifestyle, personality, attitude which can also be investigated. The study is only restricted to Business Travellers decision making pattern pertaining to their travel booking whereas a study can also be undertaken on leisure travellers decision making pattern. The study is restricted to only Delhi National Capital Region

  2. Negotiating on location, timing, duration, and participant in agent-mediated joint activity-travel scheduling

    NARCIS (Netherlands)

    Ma, Huiye; Ronald, N.A.; Arentze, T.A.; Timmermans, H.J.P.

    2013-01-01

    Agent-based simulation has become an important modeling approach in activity-travel analysis. Social activities account for a large amount of travel and have an important effect on activity-travel scheduling. Participants in joint activities usually have various options regarding location,

  3. Time-dependent variation of the neutron multiplication factor in spent fuel storage

    Energy Technology Data Exchange (ETDEWEB)

    Leotlela, M.J. [Univ. of the Witwatersrand, Johannesburg (South Africa). School of Physics; Eskom, Johannesburg (South Africa). Regulations and Licensing, Koeberg Operating Unit; Olifant, T. [Cape Town Univ. (South Africa). Dept. of Electrical Engineering and Nuclear Power Studies; Koeberg Nuclear Power Station, Cape Town (South Africa). Operating Dept.; Petr, I. [Univ. of the Witwatersrand, Johannesburg (South Africa). School of Physics

    2017-12-15

    After spent fuel assemblies have been discharged from the reactor, reactivity will fluctuate as the cooling period progresses because of changes in the number density of fissile nuclides and neutron absorber nuclides. The purpose of this project was (1) to quantify the contribution of each individual nuclide to the reactivity of the fissile system, (2) to identify nuclides that are responsible for the fluctuation in reactivity, and (3) to determine the effect of the number of nuclides on reactivity. This paper will present the results of the study of the behaviour of the k{sub eff} with respect to variation in the duration of the cooling period during storage.

  4. Catching the tail: Empirical identification of the distribution of the value of travel time

    DEFF Research Database (Denmark)

    Börjesson, Maria; Fosgerau, Mogens; Algers, Staffan

    2012-01-01

    Recent methodological advances in discrete choice analysis in combination with certain stated choice experiments have allowed researchers to check empirically the identification of the distribution of latent variables such as the value of travel time (VTT). Lack of identification is likely...... to be common and the consequences are severe. E.g., the Danish value of time study found the 15% right tail of the VTT distribution to be unidentified, making it impossible to estimate the mean VTT without resorting to strong assumptions with equally strong impact on the resulting estimate. This paper analyses...... data generated from a similar choice experiment undertaken in Sweden during 2007–2008 in which the range of tradeoff values between time and money was significantly increased relative to the Danish experiment. The results show that this change allowed empirical identification of effectively the entire...

  5. Back-in-time and faster-than-light travel in general relativity

    CERN Document Server

    Krasnikov, Serguei

    2018-01-01

    For the past 20 years causality violations and superluminal motion have been the object of intensive study as physical and geometrical phenomena. This book compiles the results of its author and also reviews other work in the field. In particular, the following popular questions are addressed:  Is causality protected by quantum divergence at the relevant Cauchy horizon?  How much "exotic matter" would it take to create a time machine or a warp drive?  What is the difference between a "discovered" time machine and a created one?  Why does a time traveler fail to kill their grandfather?  How should we define the speed of gravity and what is its magnitude?

  6. Neural activity in the medial temporal lobe reveals the fidelity of mental time travel.

    Science.gov (United States)

    Kragel, James E; Morton, Neal W; Polyn, Sean M

    2015-02-18

    Neural circuitry in the medial temporal lobe (MTL) is critically involved in mental time travel, which involves the vivid retrieval of the details of past experience. Neuroscientific theories propose that the MTL supports memory of the past by retrieving previously encoded episodic information, as well as by reactivating a temporal code specifying the position of a particular event within an episode. However, the neural computations supporting these abilities are underspecified. To test hypotheses regarding the computational mechanisms supported by different MTL subregions during mental time travel, we developed a computational model that linked a blood oxygenation level-dependent signal to cognitive operations, allowing us to predict human performance in a memory search task. Activity in the posterior MTL, including parahippocampal cortex, reflected how strongly one reactivates the temporal context of a retrieved memory, allowing the model to predict whether the next memory will correspond to a nearby moment in the study episode. A signal in the anterior MTL, including perirhinal cortex, indicated the successful retrieval of list items, without providing information regarding temporal organization. A hippocampal signal reflected both processes, consistent with theories that this region binds item and context information together to form episodic memories. These findings provide evidence for modern theories that describe complementary roles of the hippocampus and surrounding parahippocampal and perirhinal cortices during the retrieval of episodic memories, shaping how humans revisit the past. Copyright © 2015 the authors 0270-6474/15/352914-13$15.00/0.

  7. Approximate solutions for radial travel time and capture zone in unconfined aquifers.

    Science.gov (United States)

    Zhou, Yangxiao; Haitjema, Henk

    2012-01-01

    Radial time-of-travel (TOT) capture zones have been evaluated for unconfined aquifers with and without recharge. The solutions of travel time for unconfined aquifers are rather complex and have been replaced with much simpler approximate solutions without significant loss of accuracy in most practical cases. The current "volumetric method" for calculating the radius of a TOT capture zone assumes no recharge and a constant aquifer thickness. It was found that for unconfined aquifers without recharge, the volumetric method leads to a smaller and less protective wellhead protection zone when ignoring drawdowns. However, if the saturated thickness near the well is used in the volumetric method a larger more protective TOT capture zone is obtained. The same is true when the volumetric method is used in the presence of recharge. However, for that case it leads to unreasonableness over the prediction of a TOT capture zone of 5 years or more. © 2011, The Author(s). Ground Water © 2011, National Ground Water Association.

  8. Effect of percolation rate on water-travel time in deep, partially saturated zones

    International Nuclear Information System (INIS)

    Peters, R.R.; Gauthier, J.H.; Dudley, A.L.

    1986-01-01

    The Nevada Nuclear Waste Storage Investigations (NNWSI) project is investigating Yucca Mountain, Nye County, Nevada, as a prospective site for a radioactive-waste repository. The Yucca Mountain site is unique among those currently being investigated by the US Department of Energy (DOE) in that the prospective repository location is in the unsaturated zone, approximately 300 m above the water table. A composite-porosity, continuum model was developed to model flow in a fractured, porous medium. Simulations using data from the Yucca Mountain site and this model in the one-dimensional code TOSPAC indicate that current estimates of the percolation rate result in water movement confined to the matrix and that the water-travel time from the repository to the water table in on the order of hundreds of thousands of years. This result is sensitive to the percolation rate; an increase in percolation rate of a factor of 10 may initiate water movement in the fractures, reducing the travel time significantly

  9. HELIOSEISMIC HOLOGRAPHY OF SIMULATED SUNSPOTS: MAGNETIC AND THERMAL CONTRIBUTIONS TO TRAVEL TIMES

    Energy Technology Data Exchange (ETDEWEB)

    Felipe, T. [Departamento de Astrofísica, Universidad de La Laguna, E-38205 La Laguna, Tenerife (Spain); Braun, D. C.; Crouch, A. D. [NorthWest Research Associates, Colorado Research Associates, Boulder, CO 80301 (United States); Birch, A. C., E-mail: tobias@iac.es [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

    2016-10-01

    Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level in the simulations) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it would suggest a path toward inversions for sunspot structure.

  10. Effect of illegal on-street parking on travel times in urban environment

    Energy Technology Data Exchange (ETDEWEB)

    Morillo Carbonell, C.; Magin Campos Cacheda, J.

    2016-07-01

    The aim of this paper is to evaluate the effect of the on-street illegal parking on the commercial travel time of the vehicles in the area. The effect of the illegal parking in the travel time of the vehicles in the zone is analyzed in an urban scenario in order to quantify the negative impact that illegal parking implies to this, by itself, congested areas. To achieve the objective of the paper, a 3x3 street model has been designed and evaluated for different situations. In this sense, based on a traffic microsimulation model a bunch of scenarios have been considered in function of parameters referred to intensity of vehicles, illegal on street parking level and location of the illegals. Based on the scenarios mentioned, it has been analyzed the effect that the different parameters have on the commercial speed of the vehicles in order to have a first set of information that permits how to act to reduce the effect of illegal on street parking. The results obtained in this article will be able to be used in next steps in order to define direct and indirect reduction strategies referred to illegal on street parking effect. (Author)

  11. Dissolved Organic Carbon 14C in Southern Nevada Groundwater and Implications for Groundwater Travel Times

    Energy Technology Data Exchange (ETDEWEB)

    Hershey, Ronald L. [Nevada University, Reno, NV (United States). Desert Research Institute; Fereday, Wyall [Nevada University, Reno, NV (United States). Desert Research Institute; Thomas, James M [Nevada University, Reno, NV (United States). Desert Research Institute

    2016-08-01

    Dissolved inorganic carbon (DIC) carbon-14 (14C) ages must be corrected for complex chemical and physical reactions and processes that change the amount of 14C in groundwater as it flows from recharge to downgradient areas. Because of these reactions, DIC 14C can produce unrealistically old ages and long groundwater travel times that may, or may not, agree with travel times estimated by other methods. Dissolved organic carbon (DOC) 14C ages are often younger than DIC 14C ages because there are few chemical reactions or physical processes that change the amount of DOC 14C in groundwater. However, there are several issues that create uncertainty in DOC 14C groundwater ages including limited knowledge of the initial (A0) DOC 14C in groundwater recharge and potential changes in DOC composition as water moves through an aquifer. This study examines these issues by quantifying A0 DOC 14C in recharge areas of southern Nevada groundwater flow systems and by evaluating changes in DOC composition as water flows from recharge areas to downgradient areas. The effect of these processes on DOC 14C groundwater ages is evaluated and DOC and DIC 14C ages are then compared along several southern Nevada groundwater flow paths. Twenty-seven groundwater samples were collected from springs and wells in southern Nevada in upgradient, midgradient, and downgradient locations. DOC 14C for upgradient samples ranged from 96 to 120 percent modern carbon (pmc) with an average of 106 pmc, verifying modern DOC 14C ages in recharge areas, which decreases uncertainty in DOC 14C A0 values, groundwater ages, and travel times. The HPLC spectra of groundwater along a flow path in the Spring Mountains show the same general pattern indicating that the DOC compound composition does not change along this flow path

  12. How accessible are coral reefs to people? A global assessment based on travel time.

    Science.gov (United States)

    Maire, Eva; Cinner, Joshua; Velez, Laure; Huchery, Cindy; Mora, Camilo; Dagata, Stephanie; Vigliola, Laurent; Wantiez, Laurent; Kulbicki, Michel; Mouillot, David

    2016-04-01

    The depletion of natural resources has become a major issue in many parts of the world, with the most accessible resources being most at risk. In the terrestrial realm, resource depletion has classically been related to accessibility through road networks. In contrast, in the marine realm, the impact on living resources is often framed into the Malthusian theory of human density around ecosystems. Here, we develop a new framework to estimate the accessibility of global coral reefs using potential travel time from the nearest human settlement or market. We show that 58% of coral reefs are located travel time from the market is a strong predictor of fish biomass on coral reefs. We also highlight a relative deficit of protection on coral reef areas near people, with disproportional protection on reefs far from people. This suggests that conservation efforts are targeting low-conflict reefs or places that may already be receiving de facto protection due to their isolation. Our global assessment of accessibility in the marine realm is a critical step to better understand the interplay between humans and resources. © 2016 John Wiley & Sons Ltd/CNRS.

  13. HELIOSEISMIC HOLOGRAPHY OF SIMULATED SUNSPOTS: MAGNETIC AND THERMAL CONTRIBUTIONS TO TRAVEL TIMES

    International Nuclear Information System (INIS)

    Felipe, T.; Braun, D. C.; Crouch, A. D.; Birch, A. C.

    2016-01-01

    Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level in the simulations) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it would suggest a path toward inversions for sunspot structure.

  14. Multinomial model and zero-inflated gamma model to study time spent on leisure time physical activity: an example of ELSA-Brasil.

    Science.gov (United States)

    Nobre, Aline Araújo; Carvalho, Marilia Sá; Griep, Rosane Härter; Fonseca, Maria de Jesus Mendes da; Melo, Enirtes Caetano Prates; Santos, Itamar de Souza; Chor, Dora

    2017-08-17

    To compare two methodological approaches: the multinomial model and the zero-inflated gamma model, evaluating the factors associated with the practice and amount of time spent on leisure time physical activity. Data collected from 14,823 baseline participants in the Longitudinal Study of Adult Health (ELSA-Brasil - Estudo Longitudinal de Saúde do Adulto ) have been analysed. Regular leisure time physical activity has been measured using the leisure time physical activity module of the International Physical Activity Questionnaire. The explanatory variables considered were gender, age, education level, and annual per capita family income. The main advantage of the zero-inflated gamma model over the multinomial model is that it estimates mean time (minutes per week) spent on leisure time physical activity. For example, on average, men spent 28 minutes/week longer on leisure time physical activity than women did. The most sedentary groups were young women with low education level and income. The zero-inflated gamma model, which is rarely used in epidemiological studies, can give more appropriate answers in several situations. In our case, we have obtained important information on the main determinants of the duration of leisure time physical activity. This information can help guide efforts towards the most vulnerable groups since physical inactivity is associated with different diseases and even premature death.

  15. Multinomial model and zero-inflated gamma model to study time spent on leisure time physical activity: an example of ELSA-Brasil

    Directory of Open Access Journals (Sweden)

    Aline Araújo Nobre

    2017-08-01

    Full Text Available ABSTRACT OBJECTIVE To compare two methodological approaches: the multinomial model and the zero-inflated gamma model, evaluating the factors associated with the practice and amount of time spent on leisure time physical activity. METHODS Data collected from 14,823 baseline participants in the Longitudinal Study of Adult Health (ELSA-Brasil – Estudo Longitudinal de Saúde do Adulto have been analysed. Regular leisure time physical activity has been measured using the leisure time physical activity module of the International Physical Activity Questionnaire. The explanatory variables considered were gender, age, education level, and annual per capita family income. RESULTS The main advantage of the zero-inflated gamma model over the multinomial model is that it estimates mean time (minutes per week spent on leisure time physical activity. For example, on average, men spent 28 minutes/week longer on leisure time physical activity than women did. The most sedentary groups were young women with low education level and income CONCLUSIONS The zero-inflated gamma model, which is rarely used in epidemiological studies, can give more appropriate answers in several situations. In our case, we have obtained important information on the main determinants of the duration of leisure time physical activity. This information can help guide efforts towards the most vulnerable groups since physical inactivity is associated with different diseases and even premature death.

  16. Frequency Dependence of Helioseismic Measurements of the Center-to-Limb Effect and Flow-induced Travel-time Shifts

    Science.gov (United States)

    Chen, Ruizhu; Zhao, Junwei

    2018-02-01

    Time–distance helioseismology measures acoustic travel times to infer the structure and flow field of the solar interior; however, both the mean travel times and the travel-time shifts suffer systematic center-to-limb variations, which complicate the interpretation and inversions of the time–distance measurements. In particular, the center-to-limb variation in travel-time shifts (CtoL effect) has a significant impact on the inference of the Sun’s meridional circulation, and needs to be removed from the helioseismic measurements, although the observational properties and the physical cause of the CtoL effect have yet to be investigated. In this study, we measure the CtoL effect in the frequency domain using Doppler-velocity data from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager, and study its properties as a function of disk-centric distance, travel distance, and frequency of acoustic waves. It is found that the CtoL effect has a significant frequency dependence—it reverses sign at a frequency around 5.4 mHz and reaches maximum at around 4.0 mHz before the sign reversal. The tendency of frequency dependence varies with disk-centric distance in a way that both the sign-reversal frequency and the maximum-value frequency decrease closer to the limb. The variation tendency does not change with travel distance, but the variation magnitude is approximately proportional to travel distance. For comparison, the flow-induced travel-time shifts show little frequency dependence. These observational properties provide more clues on the nature of the CtoL effect, and also possibly lead to new ways of effect-removal for a more robust determination of the deep meridional flow.

  17. Intercity Travel Demand Analysis Model

    Directory of Open Access Journals (Sweden)

    Ming Lu

    2014-01-01

    Full Text Available It is well known that intercity travel is an important component of travel demand which belongs to short distance corridor travel. The conventional four-step method is no longer suitable for short distance corridor travel demand analysis for the time spent on urban traffic has a great impact on traveler's main mode choice. To solve this problem, the author studied the existing intercity travel demand analysis model, then improved it based on the study, and finally established a combined model of main mode choice and access mode choice. At last, an integrated multilevel nested logit model structure system was built. The model system includes trip generation, destination choice, and mode-route choice based on multinomial logit model, and it achieved linkage and feedback of each part through logsum variable. This model was applied in Shenzhen intercity railway passenger demand forecast in 2010 as a case study. As a result, the forecast results were consistent with the actuality. The model's correctness and feasibility were verified.

  18. Bridging Numerical and Analytical Models of Transient Travel Time Distributions: Challenges and Opportunities

    Science.gov (United States)

    Danesh Yazdi, M.; Klaus, J.; Condon, L. E.; Maxwell, R. M.

    2017-12-01

    Recent advancements in analytical solutions to quantify water and solute time-variant travel time distributions (TTDs) and the related StorAge Selection (SAS) functions synthesize catchment complexity into a simplified, lumped representation. While these analytical approaches are easy and efficient in application, they require high frequency hydrochemical data for parameter estimation. Alternatively, integrated hydrologic models coupled to Lagrangian particle-tracking approaches can directly simulate age under different catchment geometries and complexity at a greater computational expense. Here, we compare and contrast the two approaches by exploring the influence of the spatial distribution of subsurface heterogeneity, interactions between distinct flow domains, diversity of flow pathways, and recharge rate on the shape of TTDs and the relating SAS functions. To this end, we use a parallel three-dimensional variably saturated groundwater model, ParFlow, to solve for the velocity fields in the subsurface. A particle-tracking model, SLIM, is then implemented to determine the age distributions at every real time and domain location, facilitating a direct characterization of the SAS functions as opposed to analytical approaches requiring calibration of such functions. Steady-state results reveal that the assumption of random age sampling scheme might only hold in the saturated region of homogeneous catchments resulting in an exponential TTD. This assumption is however violated when the vadose zone is included as the underlying SAS function gives a higher preference to older ages. The dynamical variability of the true SAS functions is also shown to be largely masked by the smooth analytical SAS functions. As the variability of subsurface spatial heterogeneity increases, the shape of TTD approaches a power-law distribution function, including a broader distribution of shorter and longer travel times. We further found that larger (smaller) magnitude of effective

  19. 41 CFR 302-3.219 - Is there a limit on how many times I may receive reimbursement for tour renewal travel?

    Science.gov (United States)

    2010-07-01

    ... many times I may receive reimbursement for tour renewal travel? 302-3.219 Section 302-3.219 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES RELOCATION....219 Is there a limit on how many times I may receive reimbursement for tour renewal travel? (a) If you...

  20. 41 CFR 302-4.204 - If my spouse does not accompany me but travels unaccompanied at a different time, what per diem...

    Science.gov (United States)

    2010-07-01

    ... accompany me but travels unaccompanied at a different time, what per diem rate will he/she receive? 302-4.204 Section 302-4.204 Public Contracts and Property Management Federal Travel Regulation System... my spouse does not accompany me but travels unaccompanied at a different time, what per diem rate...