Murphy, Simon J
2015-01-01
We present the latest developments to the phase modulation method for finding binaries among pulsating stars. We demonstrate how the orbital elements of a pulsating binary star can be obtained analytically, that is, without converting time delays to radial velocities by numerical differentiation. Using the time delays directly offers greater precision, and allows the parameters of much smaller orbits to be derived. The method is applied to KIC9651065, KIC10990452, and KIC8264492, and a set of the orbital parameters is obtained for each system. Radial velocity curves for these stars are deduced from the orbital elements thus obtained.
Confined Quantum Time of Arrivals
Galapon, E A; Galapon, Eric A.; Bahague, Ricardo T.
2003-01-01
We show that the non-self-adjoint free time of arrival operator in free space defines a class of compact, self-adjoint, and canonical operators for a spatially confined particle. We analytically and numerically study the qualitative behaviors of these operators, and demonstrate that their eigenfunctions and eigenvalues are consistent with the interpretation that they are time of arrival operators.
HELCATS Prediction of Planetary CME arrival times
Boakes, Peter; Moestl, Christian; Davies, Jackie; Harrison, Richard; Byrne, Jason; Barnes, David; Isavnin, Alexey; Kilpua, Emilia; Rollett, Tanja
2015-04-01
We present the first results of CME arrival time prediction at different planetary locations and their comparison to the in situ data within the HELCATS project. The EU FP7 HELCATS (Heliospheric Cataloguing, Analysis & Techniques Service) is a European effort to consolidate the exploitation of the maturing field of heliospheric imaging. HELCATS aims to catalogue solar wind transients, observed by the NASA STEREO Heliospheric Imager (HI) instruments, and validate different methods for the determination of their kinematic properties. This validation includes comparison with arrivals at Earth, and elsewhere in the heliosphere, as well as onsets at the Sun (http://www.helcats-fp7.eu/). A preliminary catalogue of manually identified CMEs, with over 1000 separate events, has been created from observations made by the STEREO/HI instruments covering the years 2007-2013. Initial speeds and directions of each CME have been derived through fitting the time elongation profile to the state of the art Self-Similar Expansion Fitting (SSEF) geometric technique (Davies et al., 2012). The technique assumes that, in the plane corresponding to the position angle of interest, CMEs can be modelled as circles subtending a fixed angular width to Sun-center and propagating anti-sunward in a fixed direction at a constant speed (we use an angular width of 30 degrees in our initial results). The model has advantages over previous geometric models (e.g. harmonic mean or fixed phi) as it allows one to predict whether a CME will 'hit' a specific heliospheric location, as well as to what degree (e.g. direct assault or glancing blow). We use correction formulae (Möstl and Davies, 2013) to convert CME speeds, direction and launch time to speed and arrival time at any in situ location. From the preliminary CME dataset, we derive arrival times for over 400 Earth-directed CMEs, and for over 100 Mercury-, Venus-, Mars- and Saturn-directed CMEs predicted to impact each planet. We present statistics of
Confined Quantum Time of Arrival for Vanishing Potential
Galapon, E A; Caballar, R F; Bahague, Ricardo; Caballar, Roland F.; Galapon, Eric A.
2005-01-01
We give full account of our recent report in [E.A. Galapon, R. Caballar, R. Bahague {\\it Phys. Rev. Let.} {\\bf 93} 180406 (2004)] where it is shown that formulating the free quantum time of arrival problem in a segment of the real line suggests rephrasing the quantum time of arrival problem to finding a complete set of states that evolve to unitarily arrive at a given point at a definite time. For a spatially confined particle, here it is shown explicitly that the problem admits a solution in the form of an eigenvalue problem of a class of compact and self-adjoint time of arrival operators derived by a quantization of the classical time of arrival. The eigenfunctions of these operators are numerically demonstrated to unitarilly arrive at the origin at their respective eigenvalues.
Theory of Confined Quantum Time of Arrivals
Galapon, E A
2005-01-01
We extend the concept of confined quantum time of arrival operators, first developed for the free particle [E.A. Galapon, R. Caballar, R. Bahague {\\it Phys. Rev. Let.} {\\bf 93} 180406 (2004)], to arbitrary potentials.
CONSTRUCTION OF CONTINUOUS TIME MARKOVIAN ARRIVAL PROCESSES
Institute of Scientific and Technical Information of China (English)
Qi-Ming HE
2010-01-01
Markovian arrival processes were introduced by Neuts in 1979(Neuts 1979)and have been used extensively in the stochastic modeling of queueing,inventory,reliability,risk,and telecommunications systems.In this paper,we introduce a constructive approach to define continuous time Markovian arrival processes.The construction is based on Poisson processes,and is simple and intuitive.Such a construction makes it easy to interpret the parameters of Markovian arrival processes.The construction also makes it possible to establish rigorously basic equations,such as Kolmogorov differential equations,for Markovian arrival processes,using only elementary properties of exponential distributions and Poisson processes.In addition,the approach can be used to construct continuous time Markov chains with a finite number of states
Managing customer arrivals with time windows
DEFF Research Database (Denmark)
Chen, Gang; Jiang, Liping
2016-01-01
Due to increasing container traffic and mega-ships, many seaports face challenges of huge amounts of truck arrivals and congestion problem at terminal gates, which affect port efficiency and generate serious air pollution. To solve this congestion problem, we propose a solution of managing truck...... arrivals with time windows based on the truck-vessel service relationship, specifically trucks delivering containers for the same vessel share one common time window. Time windows can be optimized with different strategies. In this paper, we first propose a framework for installing this solution...
Quantum arrival time measurement and backflow effect
Muga, J G; Leavens, C R
1999-01-01
The current density for a freely evolving state without negative momentum components can temporarily be negative. The operational arrival time distribution, defined by the absorption rate of an ideal detector, is calculated for a model detector and compared with recently proposed distributions. Counterintuitive features of the backflow regime are discussed.
Scheduling jobs that arrive over time
Energy Technology Data Exchange (ETDEWEB)
Phillips, C. [Sandia National Labs., Albuquerque, NM (United States); Stein, C. [Dartmouth Coll., Hanover, NH (United States); Wein, J. [Polytechnic Univ., Brooklyn, NY (United States). Dept. of Computer Science
1995-04-06
A natural and basic problem in scheduling theory is to provide good average quality of service to a stream of jobs that arrive over time. In this paper we consider the problem of scheduling n jobs that are released over time in order to minimize the average completion time of the set of jobs. In contrast to the problem of minimizing average completion time when all jobs are available at time 0, all the problems that we consider are NP-hard, and essentially nothing was known about constructing good approximations in polynomial time. We give the first constant-factor approximation algorithms for several variants of the single and parallel machine model. Many of the algorithms are based on interesting algorithmic and structural relationships between preemptive and nonpreemptive schedules and linear programming relaxations of both. Many of the algorithms generalize to the minimization of average weighted completion time as well.
Discrete time queues with phase dependent arrivals
Daigle, J. N.; Lee, Y.; Magalhaes, M. N.
1994-02-01
The queueing behavior of many communication systems is well modeled by a queueing system in which time is slotted, and the number of entities that arrive during a slot is dependent upon the state of a discrete time, discrete state Markov chain. Techniques for analyzing such systems have appeared in the literature from time to time, but distributions have been presented in only rare instances. In this paper, we present the probability generating function (PGF) for joint and marginal buffer occupancy distributions of statistical time division multiplexing systems in this class. We discuss inversion of the PGF using discrete Fourier transforms, and also discuss a simple technique for obtaining moments of the queue length distribution. Numerical results, including queue length distributions for some special cases, are presented.
True Time API Link (real time arrival info)
Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This link will take you to the site where you can create an account to access Port Authority's real time arrival information. To request access to Port Authority's...
Modelling tourists arrival using time varying parameter
Suciptawati, P.; Sukarsa, K. G.; Kencana, Eka N.
2017-06-01
The importance of tourism and its related sectors to support economic development and poverty reduction in many countries increase researchers’ attentions to study and model tourists’ arrival. This work is aimed to demonstrate time varying parameter (TVP) technique to model the arrival of Korean’s tourists to Bali. The number of Korean tourists whom visiting Bali for period January 2010 to December 2015 were used to model the number of Korean’s tourists to Bali (KOR) as dependent variable. The predictors are the exchange rate of Won to IDR (WON), the inflation rate in Korea (INFKR), and the inflation rate in Indonesia (INFID). Observing tourists visit to Bali tend to fluctuate by their nationality, then the model was built by applying TVP and its parameters were approximated using Kalman Filter algorithm. The results showed all of predictor variables (WON, INFKR, INFID) significantly affect KOR. For in-sample and out-of-sample forecast with ARIMA’s forecasted values for the predictors, TVP model gave mean absolute percentage error (MAPE) as much as 11.24 percent and 12.86 percent, respectively.
Quantum arrival-time distributions from intensity functions
DEFF Research Database (Denmark)
Wlodarz, Joachim
2002-01-01
The quantum time-of-arrival problem is discussed within the standard formulation of nonrelativistic quantum mechanics with parametric time. It is shown that a general class of arrival-time probability distributions results from the assumption that the arrival process of a quantum particle...
Time of arrival based location estimation for cooperative relay networks
Çelebi, Hasari Burak
2010-09-01
In this paper, we investigate the performance of a cooperative relay network performing location estimation through time of arrival (TOA). We derive Cramer-Rao lower bound (CRLB) for the location estimates using the relay network. The analysis is extended to obtain average CRLB considering the signal fluctuations in both relay and direct links. The effects of the channel fading of both relay and direct links and amplification factor and location of the relay node on average CRLB are investigated. Simulation results show that the channel fading of both relay and direct links and amplification factor and location of relay node affect the accuracy of TOA based location estimation. ©2010 IEEE.
Sojourn time distributions in a Markovian G-queue with batch arrival and batch removal
1999-01-01
We consider a single server Markovian queue with two types of customers; positive and negative, where positive customers arrive in batches and arrivals of negative customers remove positive customers in batches. Only positive customers form a queue and negative customers just reduce the system congestion by removing positive ones upon their arrivals. We derive the LSTs of sojourn time distributions for a single server Markovian queue with positive customers and negative custom...
Localization of a noisy broadband surface target using time differences of multipath arrivals.
Gebbie, John; Siderius, Martin; McCargar, Reid; Allen, John S; Pusey, Grant
2013-07-01
Previous studies [Tiemann et al., J. Acoust. Soc. Am. 120, 2355-2365 (2006)] have reported the localization of marine mammals in 3-D from their clicks using multipath arrivals. Bathymetric variations were advantageously used to predict multipath arrival times with a raytracer. These arrivals are directly discernible from the time series for impulsive sources, such as whale clicks, but extension of the method to continuous broadband sources presents additional complications. By pulse compressing noise emitted from a small boat using two hydrophones, the hyperbolic direct-arrival ambiguity can be refined in both range and bearing. Acoustic-derived results are validated with target GPS measurements.
Confined Quantum Time of Arrival for Vanishing Potential
2005-01-01
We give full account of our recent report in [E.A. Galapon, R. Caballar, R. Bahague {\\it Phys. Rev. Let.} {\\bf 93} 180406 (2004)] where it is shown that formulating the free quantum time of arrival problem in a segment of the real line suggests rephrasing the quantum time of arrival problem to finding a complete set of states that evolve to unitarily arrive at a given point at a definite time. For a spatially confined particle, here it is shown explicitly that the problem admits a solution in...
Estimated time of arrival and debiasing the time saving bias.
Eriksson, Gabriella; Patten, Christopher J D; Svenson, Ola; Eriksson, Lars
2015-01-01
The time saving bias predicts that the time saved when increasing speed from a high speed is overestimated, and underestimated when increasing speed from a slow speed. In a questionnaire, time saving judgements were investigated when information of estimated time to arrival was provided. In an active driving task, an alternative meter indicating the inverted speed was used to debias judgements. The simulated task was to first drive a distance at a given speed, and then drive the same distance again at the speed the driver judged was required to gain exactly 3 min in travel time compared with the first drive. A control group performed the same task with a speedometer and saved less than the targeted 3 min when increasing speed from a high speed, and more than 3 min when increasing from a low speed. Participants in the alternative meter condition were closer to the target. The two studies corroborate a time saving bias and show that biased intuitive judgements can be debiased by displaying the inverted speed. Practitioner Summary: Previous studies have shown a cognitive bias in judgements of the time saved by increasing speed. This simulator study aims to improve driver judgements by introducing a speedometer indicating the inverted speed in active driving. The results show that the bias can be reduced by presenting the inverted speed and this finding can be used when designing in-car information systems.
Method and device for signal time of arrival determination
Bellusci, G.; Janssen, G.J.M.
2010-01-01
A method for determining a time-of-arrival of an input signal, includes receiving the input signal; generating a first time dependent signal with a first time dependence from the received 5 input signal; generating a second time dependent signal with a second time dependence from the received input
Sojourn time distributions in a Markovian G-queue with batch arrival and batch removal
Directory of Open Access Journals (Sweden)
Yang Woo Shin
1999-01-01
Full Text Available We consider a single server Markovian queue with two types of customers; positive and negative, where positive customers arrive in batches and arrivals of negative customers remove positive customers in batches. Only positive customers form a queue and negative customers just reduce the system congestion by removing positive ones upon their arrivals. We derive the LSTs of sojourn time distributions for a single server Markovian queue with positive customers and negative customers by using the first passage time arguments for Markov chains.
The time of arrival concept in quantum mechanics
Muga, J G; Palao, J P
1998-01-01
The concept and the formalization of the arrival time in quantum mechanics are discussed. Different approaches based on trajectories, quantization rules, time operators, phase space techniques, renewal equations or operational procedures are reviewed or proposed. Open questions and loose ends are pointed out.
Spectral information for detection of acoustic time to arrival
DEFF Research Database (Denmark)
Gordon, Michael S.; Russo, Frank A.; MacDonald, Ewen
2013-01-01
The exponential increase of intensity for an approaching sound source provides salient information for a listener to make judgments of time to arrival (TTA). Specifically, a listener will experience a greater rate of increasing intensity for higher than for lower frequencies during a sound source......’s approach. To examine the relative importance of this spectral information, listeners were asked to make judgments about the arrival times of nine 1-octave-band sound sources (the bands were consecutive, nonoverlapping single octaves, ranging from 40–80 Hz to ~10–20 kHz). As is typical in TTA tasks...
Static Behaviors of Confined Time-Arrival Operators
2003-01-01
We show that the quantization of the classical Time-of-Arrival (TOA) for arbitrary position X still leadsto a class of self-adjoint TOA-operator for a confined particle. The spectrum of the TOA-operator isstudied for different cases.
Time of arrival estimation in pulsar-based navigation systems
Kabakchiev, Chr.; Behar, V.; Buist, P.; Garvanov, I.; Kabakchieva, D.; Bentum, M.J.
2015-01-01
This paper focuses on the Time of Arrival (TOA) estimation problem related to new application of pulsar signals for airplane-based navigation. The aim of the paper is to propose and evaluate a possible algorithm for TOA estimation that consists of epoch folding, filtering, CFAR detection, crosscorre
Institute of Scientific and Technical Information of China (English)
HE Xiao-bo; ZHOU Hui-lan
2005-01-01
The arrival times of first teleseismic phases are difficult to be measured precisely because of slowly and gradually changed onsets and weak amplitudes. The arrival times measured manually are usually behind the real ones. In this paper, using the ratio method of fixed scale wavelet transformations improved by us, the arrival times for the first arrival phases (such as P and PKIKP) at the teleseismic and far-teleseimic distances were measured. The results are reasonable and reliable based on the analysis and discussion of the reliabilifies and errors.
Sistem Deteksi Petir Multistation Dengan Metode Time of Arrival
Directory of Open Access Journals (Sweden)
Dasrinal Tessal
2015-03-01
Full Text Available This study was done at ligtning detection system in Padang. The systems was consist of 3 electric field sensors with synchronous satelite GPS. Time of arrival and sensors coordinate was taken from each sensors. This data was used to calculate ligtning location by Time of Arrival Linear Spherical method. Then the distances between lighting and sensor can be calculated. The distances will compared with electric field waveforms recorded at lightning sensor to testing validity our results. After validity, lightning current peak can be calculated. 8 of 20 data sample are valid with lowest lightning current peak is -1,001 kA dan highest value is -2,661 kA.
Empirical estimation of the arrival time of ICME Shocks
Shaltout, Mosalam
Empirical estimation of the arrival time of ICME Shocks Mosalam Shaltout1 ,M.Youssef 1and R.Mawad2 1 National Research Institute of Astronomy and Geophysics (NRIAG) ,Helwan -Cairo-Egypt Email: mosalamshaltout@hotmail.com 2 Faculty of Science-Monifiia University-Physics Department-Shiben Al-Koum -Monifiia-Egypt We are got the Data of the SSC events from Preliminary Reports of the ISGI (Institut de Physique du Globe, France) .Also we are selected the same CME interval 1996-2005 from SOHO/LASCO/C2.We have estimated the arrival time of ICME shocks during solar cycle 23rd (1996-2005), we take the Sudden storm commencement SSC as a indicator of the arrival of CMEs at the Earth's Magnetosphere (ICME).Under our model ,we selected 203 ICME shock-SSC associated events, we got an imperial relation between CME velocity and their travel time, from which we obtained high correlation between them, R=0.75.
Space-time properties of free-motion time-of-arrival eigenfunctions
Muga, J G; Palao, J P
1998-01-01
The properties of the time-of-arrival operator for free motion introduced by Aharonov and Bohm and of its self-adjoint variants are studied. The domains of applicability of the different approaches are clarified. It is shown that the arrival time of the eigenstates is not sharply defined. However, strongly peaked real-space (normalized) wave packets constructed with narrow Gaussian envelopes centred on one of the eigenstates provide an arbitrarily sharp arrival time.
Li, Xinya; Deng, Zhiqun Daniel; Rauchenstein, Lynn T.; Carlson, Thomas J.
2016-04-01
Locating the position of fixed or mobile sources (i.e., transmitters) based on measurements obtained from sensors (i.e., receivers) is an important research area that is attracting much interest. In this paper, we review several representative localization algorithms that use time of arrivals (TOAs) and time difference of arrivals (TDOAs) to achieve high signal source position estimation accuracy when a transmitter is in the line-of-sight of a receiver. Circular (TOA) and hyperbolic (TDOA) position estimation approaches both use nonlinear equations that relate the known locations of receivers and unknown locations of transmitters. Estimation of the location of transmitters using the standard nonlinear equations may not be very accurate because of receiver location errors, receiver measurement errors, and computational efficiency challenges that result in high computational burdens. Least squares and maximum likelihood based algorithms have become the most popular computational approaches to transmitter location estimation. In this paper, we summarize the computational characteristics and position estimation accuracies of various positioning algorithms. By improving methods for estimating the time-of-arrival of transmissions at receivers and transmitter location estimation algorithms, transmitter location estimation may be applied across a range of applications and technologies such as radar, sonar, the Global Positioning System, wireless sensor networks, underwater animal tracking, mobile communications, and multimedia.
Refraction Static Correction without Picking First Arrival Times
Directory of Open Access Journals (Sweden)
Chien-Ying Wang
2009-01-01
Full Text Available A concept of differential delay time is proposed for refraction static correction without picking first arrival times in the CDP reflection data processing. This new method is a modification of the ABCD method; it uses cross-correlation to measure the first arrival time difference between signals received at stations B and C, instead of directly computing them from their picked times. By taking advantage of multiple-fold CDP data, we apply the "line-up trace" measurement of cross-correlations, which may alleviate the effect of data imperfections. The problem of refractor velocity variation has also been solved to a certain extent, which allows for a reliable delay time to be adequately estimated for each station and consequently the static correction value. A synthetic model and a real case with a severe weathered layer problem have been tested to evaluate the method. Stable and man age able computation processes have been explored to attain the maximum performance. The results are quite satisfactory. It should be possible to apply this method in rough areas with complicated refraction static problem, even in 3D cases.
Arrival time distribution of muons in extensive air showers
Energy Technology Data Exchange (ETDEWEB)
Villiers, E.J. de; Walt, D.J. van der; Urk, G. van; Grieder, P.K.F.
1986-06-01
The longitudinal structure of the muon disc has been studied up to distances of 60 m from the shower axis by measuring the relative arrival times between single muons in extensive air showers with particle numbers of 1 x 10/sup 5/ to 2 x 10/sup 7/. A rather constant thickness of the shower disc was found up to 60 m from the shower axis. The longitudinal distribution up to 30 m from the shower axis is not in agreement with the results from a shower model with a fairly high multiplicity rule for secondary particle formation in hadron interactions.
Probability distribution of arrival times in quantum mechanics
Delgado, V
1998-01-01
In a previous paper [Phys. Rev. A, in press] we introduced a self-adjoint operator $\\hat {{\\cal T}}(X)$ whose eigenstates can be used to define consistently a probability distribution of the time of arrival at a given spatial point. In the present work we show that the probability distribution previously proposed can be well understood on classical grounds in the sense that it is given by the expectation value of a certain positive definite operator $\\hat J^{(+)}(X)$ which is nothing but a straightforward quantum version of the modulus of the classical current. For quantum states highly localized in momentum space about a certain momentum $p_0 \
Accurate determination of phase arrival times using autoregressive likelihood estimation
Directory of Open Access Journals (Sweden)
G. Kvaerna
1994-06-01
Full Text Available We have investigated the potential automatic use of an onset picker based on autoregressive likelihood estimation. Both a single component version and a three component version of this method have been tested on data from events located in the Khibiny Massif of the Kola peninsula, recorded at the Apatity array, the Apatity three component station and the ARCESS array. Using this method, we have been able to estimate onset times to an accuracy (standard deviation of about 0.05 s for P-phases and 0.15 0.20 s for S phases. These accuracies are as good as for analyst picks, and are considerably better than the accuracies of the current onset procedure used for processing of regional array data at NORSAR. In another application, we have developed a generic procedure to reestimate the onsets of all types of first arriving P phases. By again applying the autoregressive likelihood technique, we have obtained automatic onset times of a quality such that 70% of the automatic picks are within 0.1 s of the best manual pick. For the onset time procedure currently used at NORSAR, the corresponding number is 28%. Clearly, automatic reestimation of first arriving P onsets using the autoregressive likelihood technique has the potential of significantly reducing the retiming efforts of the analyst.
Prediction of shock arrival times from CME and flare data
Núñez, Marlon; Nieves-Chinchilla, Teresa; Pulkkinen, Antti
2016-08-01
This paper presents the Shock Arrival Model (SARM) for predicting shock arrival times for distances from 0.72 AU to 8.7 AU by using coronal mass ejections (CME) and flare data. SARM is an aerodynamic drag model described by a differential equation that has been calibrated with a data set of 120 shocks observed from 1997 to 2010 by minimizing the mean absolute error (MAE), normalized to 1 AU. SARM should be used with CME data (radial, earthward, or plane-of-sky speeds) and flare data (peak flux, duration, and location). In the case of 1 AU, the MAE and the median of absolute errors were 7.0 h and 5.0 h, respectively, using the available CME/flare data. The best results for 1 AU (an MAE of 5.8 h) were obtained using both CME data, either radial or cone model-estimated speeds, and flare data. For the prediction of shock arrivals at distances from 0.72 AU to 8.7 AU, the normalized MAE and the median were 7.1 h and 5.1 h, respectively, using the available CME/flare data. SARM was also calibrated to be used with CME data alone or flare data alone, obtaining normalized MAE errors of 8.9 h and 8.6 h, respectively, for all shock events. The model verification was carried out with an additional data set of 20 shocks observed from 2010 to 2012 with radial CME speeds to compare SARM with the empirical ESA model and the numerical MHD-based ENLIL model. The results show that the ENLIL's MAE was lower than the SARM's MAE, which was lower than the ESA's MAE. The SARM's best results were obtained when both flare and true CME speeds were used.
Energy Technology Data Exchange (ETDEWEB)
Li, Xinya [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Deng, Zhiqun Daniel [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Rauchenstein, Lynn T. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Carlson, Thomas J. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
2016-04-01
Locating the position of fixed or mobile sources (i.e., transmitters) based on received measurements from sensors is an important research area that is attracting much research interest. In this paper, we present localization algorithms using time of arrivals (TOA) and time difference of arrivals (TDOA) to achieve high accuracy under line-of-sight conditions. The circular (TOA) and hyperbolic (TDOA) location systems both use nonlinear equations that relate the locations of the sensors and tracked objects. These nonlinear equations can develop accuracy challenges because of the existence of measurement errors and efficiency challenges that lead to high computational burdens. Least squares-based and maximum likelihood-based algorithms have become the most popular categories of location estimators. We also summarize the advantages and disadvantages of various positioning algorithms. By improving measurement techniques and localization algorithms, localization applications can be extended into the signal-processing-related domains of radar, sonar, the Global Positioning System, wireless sensor networks, underwater animal tracking, mobile communications, and multimedia.
Time-of-arrival distribution for arbitrary potentials and Wigner's time-energy uncertainty relation
Baute, A D; Palao, J P; Muga, J G; Egusquiza, I L
2000-01-01
A realization of the concept of "crossing state" invoked, but not implemented, by Wigner, allows to advance in two important aspects of the time of arrival in quantum mechanics: (i) For free motion, we find that the limitations described by Aharonov et al. in Phys. Rev. A 57, 4130 (1998) for the time-of-arrival uncertainty at low energies for certain mesurement models are in fact already present in the intrinsic time-of-arrival distribution of Kijowski; (ii) We have also found a covariant generalization of this distribution for arbitrary potentials and positions.
Traffic Incident Clearance Time and Arrival Time Prediction Based on Hazard Models
Directory of Open Access Journals (Sweden)
Yang beibei Ji
2014-01-01
Full Text Available Accurate prediction of incident duration is not only important information of Traffic Incident Management System, but also an effective input for travel time prediction. In this paper, the hazard based prediction models are developed for both incident clearance time and arrival time. The data are obtained from the Queensland Department of Transport and Main Roads’ STREAMS Incident Management System (SIMS for one year ending in November 2010. The best fitting distributions are drawn for both clearance and arrival time for 3 types of incident: crash, stationary vehicle, and hazard. The results show that Gamma, Log-logistic, and Weibull are the best fit for crash, stationary vehicle, and hazard incident, respectively. The obvious impact factors are given for crash clearance time and arrival time. The quantitative influences for crash and hazard incident are presented for both clearance and arrival. The model accuracy is analyzed at the end.
Measuring pulse times of arrival from broadband pulsar observations
Liu, K; Cognard, I; Stappers, B W; Verbiest, J P W; Lee, K J; Champion, D J; Kramer, M; Freire, P C C; Karuppusamy, R
2014-01-01
In recent years, instrumentation enabling pulsar observations with unprecedentedly high fractional bandwidth has been under development which can be used to substantially improve the precision of pulsar timing experiments. The traditional template-matching method used to calculate pulse times-of-arrival (ToAs), may not function effectively on these broadband data due to a variety of effects such as diffractive scintillation in the interstellar medium, profile variation as a function of frequency, dispersion measure (DM) evolution and so forth. In this paper, we describe the channelised Discrete Fourier Transform method that can greatly mitigate the influence of the aforementioned effects when measuring ToAs from broadband timing data. The method is tested on simulated data, and its potential in improving timing precision is shown. We further apply the method to PSR J1909$-$3744 data collected at the Nan\\c{c}ay Radio Telescope with the Nan\\c{c}ay Ultimate Pulsar Processing Instrument. We demonstrate a removal ...
Challenges of modeling solar disturbances' arrival times at the Earth
Institute of Scientific and Technical Information of China (English)
S. T. WU; Ai-Hua WANG; C. D. FRY; XueShang FENG; Chin-Chun WU; Murray DRYER
2008-01-01
In recent years remarkable advances have been made in the development of phys-ics based models of various parts of the solar-terrestrial system (see JASTP special issues, October, November 2004; February 2007). In this paper, we focus our dis-cussions in a specific region of the Sun to the Earth's environment (i.e. 1 AU). It is well-known that geomagnetic storms are caused by solar eruptions. The conse-quences of these storms include particle acceleration, solar wind impact on the Earth's magnetosphere and ionosphere, UV-EUV radiation effects on the lower at-mosphere, etc. One of the main challenges is to predict the arrival time at 1 AU of the solar disturbance. The prospects look good for an accurate, real-time forecast scheme built on the acquisition of solar, heliosphere and the near-Earth data and large-scale models. However, the accuracy of these models still needs improve-ment. We will discuss the present status of the models and challenges to improve the simulation models.
Challenges of modeling solar disturbances’ arrival times at the Earth
Institute of Scientific and Technical Information of China (English)
C.; D.; FRY; Chin-Chun; WU; Murray; DRYER
2008-01-01
In recent years remarkable advances have been made in the development of phys-ics based models of various parts of the solar-terrestrial system (see JASTP special issues, October, November 2004; February 2007). In this paper, we focus our dis-cussions in a specific region of the Sun to the Earth’s environment (i.e. 1 AU). It is well-known that geomagnetic storms are caused by solar eruptions. The conse-quences of these storms include particle acceleration, solar wind impact on the Earth’s magnetosphere and ionosphere, UV-EUV radiation effects on the lower at-mosphere, etc. One of the main challenges is to predict the arrival time at 1 AU of the solar disturbance. The prospects look good for an accurate, real-time forecast scheme built on the acquisition of solar, heliosphere and the near-Earth data and large-scale models. However, the accuracy of these models still needs improve-ment. We will discuss the present status of the models and challenges to improve the simulation models.
Semi-coherent time of arrival estimation using regression.
Apartsin, Alexander; Cooper, Leon N; Intrator, Nathan
2012-08-01
Time of arrival (ToA) estimation is essential for many types of remote sensing applications including radar, sonar, and underground exploration. The standard method for ToA estimation employs a matched filter for computing the maximum likelihood estimator (MLE) for ToA. The accuracy of the MLE decreases rapidly whenever the amount of noise in a received signal rises above a certain threshold. This well-known threshold effect is unavoidable in several important applications due to various limitations on the power and the spectrum of a narrowband source pulse. A measurement performed in the presence of the threshold effect employs a receiver which operates in the semi-coherent state. Therefore, the conventional methods assuming a coherent state receiver should be adapted to the semi-coherent case. In this paper, a biosonar-inspired method for the semi-coherent ToA estimation is described. The method abandons the exploration of an echo signal by a single matched filter in favor of the analysis by multiple phase-shifted unmatched filters. Each phase-shifted unmatched filter gives rise to a biased ToA estimator. The described method uses regression for combining these estimators into a single unbiased ToA estimator that outperform the MLE in the presence of the threshold effect.
Hrabe, J.; Lewis, D. P.
2004-03-01
A fairly general theoretical model for pulsed arterial spin labeling perfusion methods has been available for some time but analytical solutions were derived for only a small number of arterial blood input functions. These mostly assumed a sudden and simultaneous arrival of the tagged blood into the imaged region. More general cases had to be handled numerically. We present analytical solutions for two more realistic arterial input functions. They both allow the arrival times of the molecules of tagged arterial blood to be statistically distributed. We consider cases of (1) a uniform distribution on a finite time interval and (2) a normal distribution characterized by its mean and standard deviation. These models are physiologically meaningful because the statistical nature of the arrival times reflects the distribution of velocities and path lengths that the blood water molecules undertake from the tagging region to the imaged region. The model parameters can be estimated from the measured dependency of the perfusion signal on the tag inversion time.
Time-dependent solution for the manufacturing line with unreliable machine and batched arrivals
Kempa, W. M.; Paprocka, I.; Grabowik, C.; Kalinowski, K.
2015-11-01
Time-dependent queue-size distribution in a finite-buffer manufacturing line with unreliable machine is investigated. Successive jobs arrive in batches (groups) with sizes being generally distributed random variables, and are being processed individually with exponential service times. Applying the approach based on the memory less property of exponential distribution and the total probability law, a system of integral equations for the transient queue- size distribution conditioned by the initial level of buffer saturation is derived. The solution of the corresponding system written for Laplace transforms is found via linear-algebraic approach.
Institute of Scientific and Technical Information of China (English)
Zhao Haijun; Ma Yan; Huang Xiaohong; Su Yujie
2008-01-01
Predicting heartbeat message arrival time is crucial for the quality of failure detection service over internet. However, internet dynamic characteristics make it very difficult to understand message behavior and accurately predict heartbeat arrival time. To solve this problem, a novel black-box model is proposed to predict the next heartbeat arrival time. Heartbeat arrival time is modeled as auto-regressive process, heartbeat sending time is modeled as exogenous variable, the model's coefficients are estimated based on the sliding window of observations and this result is used to predict the next heartbeat arrival time. Simulation shows that this adaptive auto-regressive exogenous (ARX) model can accurately capture heartbeat arrival dynamics and minimize prediction error in different network environments.
A Fast-Time Simulation Tool for Analysis of Airport Arrival Traffic
Erzberger, Heinz; Meyn, Larry A.; Neuman, Frank
2004-01-01
The basic objective of arrival sequencing in air traffic control automation is to match traffic demand and airport capacity while minimizing delays. The performance of an automated arrival scheduling system, such as the Traffic Management Advisor developed by NASA for the FAA, can be studied by a fast-time simulation that does not involve running expensive and time-consuming real-time simulations. The fast-time simulation models runway configurations, the characteristics of arrival traffic, deviations from predicted arrival times, as well as the arrival sequencing and scheduling algorithm. This report reviews the development of the fast-time simulation method used originally by NASA in the design of the sequencing and scheduling algorithm for the Traffic Management Advisor. The utility of this method of simulation is demonstrated by examining the effect on delays of altering arrival schedules at a hub airport.
Community assembly in experimental grasslands: suitable environment or timely arrival?
Ejrnaes, Rasmus; Bruun, Hans Henrik; Graae, Bente J
2006-05-01
It is hard to defend the view that biotic communities represent a simple and predictable response to the abiotic environment. Biota and the abiotic environment interact, and the environment of an individual certainly includes its neighbors and visitors in the community. The complexity of community assembly calls forth a quest for general principles, yet current results and theories on assembly rules differ widely. Using a grassland microcosm as a model system, we manipulated fertility, disturbance by defoliation, soil/microclimate, and arrival order of species belonging to two groups differing in functional attributes. We analyzed the outcome of community assembly dynamics in terms of species richness, invasibility, and species composition. The analyses revealed strong environmental control over species richness and invasibility. Species composition was mainly determined by the arrival order of species, indicating that historical contingency may change the outcome of community assembly. The probability for multiple equilibria appeared to increase with productivity and environmental stability. The importance of arrival order offers an explanation of the difficulties in predicting local occurrences of species in the field. In our experiment, variation in fertility and disturbance was controlling colonization with predictable effects on emergent community properties such as species richness. The key mechanism is suggested to be asymmetric competition, and our results show that this mechanism is relatively insensitive to the species through which it works. While our analyses indicate a positive and significant correlation between richness and invasibility, the significance disappears after accounting for the effect of the environment. The importance of arrival order (historical contingency) and environmental control supports the assumption of the unified neutral theory that different species within a trophic level can be considered functionally equivalent when it comes
Comparing seismic tomographic images from automatically- and manually-detected arrival times
Spallarossa, Daniele; Scafidi, Davide; Turino, Chiara; Ferretti, Gabriele; Viganò, Alfio
2013-04-01
In this work we compare local earthquake tomographic images obtained using arrival times detected by an automatic picking procedure and by an expert seismologist. For this purpose we select a reference dataset composed of 476 earthquakes occurred in the Trentino region (north-eastern Italy) in the period 1994-2007. Local magnitudes are comprised between 0.8 and 5.3. Original recordings are mainly from the Provincia Autonoma di Trento (PAT), and from other networks operating in the surrounding areas (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - INOGS; Istituto Nazionale di Geofisica e Vulcanologia - INGV; others available via the European Integrated Data Archive). The automatic picking of P and S phases is performed through a picker engine based on the Akaike information criterion (AIC). In particular, the proposed automatic phase picker includes: (i) envelope calculation, (ii) band-pass filtering, (iii) Akaike information criterion (AIC) detector for both P- and S-arrivals, (iv) checking for impulsive arrivals, (v) evaluation of expected S onset on the basis of a preliminary location derived from the P-arrival times, and (vi) quality assessment. Simultaneously, careful manual inspection by expert seismologists is applied to the same waveform dataset, to obtain manually-repicked phase readings. Both automatic and manual procedures generate a comparable amount of readings (about 6000 P- and 5000 S-phases). These data are used for the determination of two similar 3-D propagation models for the Trentino region, applying the SIMULPS code. In order to quantitatively estimate the difference of these two models we measure their discrepancies in terms of velocity at all grid points. The small differences observed among tomographic results allow us to demonstrate that the automatic picking engine adopted in this test can be used for reprocessing large amount of seismic recordings with the aim of perform a local tomographic study with an accuracy
Transition from discrete to continuous time of arrival distribution for a quantum particle
Galapon, E A; Egusquiza, I; Muga, J G; Egusquiza, Inigo; Galapon, Eric A.
2005-01-01
We show that the Kijowski distribution for time of arrivals in the entire real line is the limiting distribution of the time of arrival distribution in a confining box as its length increases to infinity. The dynamics of the confined time of arrival eigenfunctions is also numerically investigated and demonstrated that the eigenfunctions evolve to have point supports at the arrival point at their respective eigenvalues in the limit of arbitrarilly large confining lengths, giving insight into the ideal physical content of the Kijowsky distribution.
Timing the Random and Anomalous Arrival of Particles in a Geiger Counter with GPS Devices
Blanco, F.; La Rocca, P.; Riggi, F.; Riggi, S.
2008-01-01
The properties of the arrival time distribution of particles in a detector have been studied by the use of a small Geiger counter, with a GPS device to tag the event time. The experiment is intended to check the basic properties of the random arrival time distribution between successive events and to simulate the investigations carried out by…
van der Spoel, Sjoerd; Amrit, Chintan Amrit; van Hillegersberg, Jos
2017-01-01
Distribution centres (DCs) are the hubs connecting transport streams in the supply chain. The synchronisation of coming and going cargo at a DC requires reliable arrival times. To achieve this, a reliable method to predict arrival times is needed. A literature review was performed to find the factor
Spoel, van der Sjoerd; Amrit, Chintan; Hillegersberg, van Jos
2015-01-01
Distribution centres (DCs) are the hubs connecting transport streams in the supply chain. The synchronisation of coming and going cargo at a DC requires reliable arrival times. To achieve this, a reliable method to predict arrival times is needed. A literature review was performed to find the factor
León-Jiménez, C; Ruiz-Sandoval, J L; Chiquete, E; Vega-Arroyo, M; Arauz, A; Murillo-Bonilla, L M; Ochoa-Guzmán, A; Carrillo-Loza, K; Ramos-Moreno, A; Barinagarrementeria, F; Cantú-Brito, C
2014-05-01
Information regarding hospital arrival times after acute ischaemic stroke (AIS) has mainly been gathered from countries with specialised stroke units. Little data from emerging nations is available. We aim to identify factors associated with achieving hospital arrival times of less than 1, 3, and 6 hours, and analyse how arrival times are related to functional outcomes after AIS. We analysed data from patients with AIS included in the PREMIER study (Primer Registro Mexicano de Isquemia Cerebral) which defined time from symptom onset to hospital arrival. The functional prognosis at 30 days and at 3, 6, and 12 months was evaluated using the modified Rankin Scale. Among 1096 patients with AIS, 61 (6%) arrived in <1 hour, 250 (23%) in <3 hours, and 464 (42%) in <6 hours. The factors associated with very early (<1 hour) arrival were family history of ischemic heart disease and personal history of migraines; in <3 hours: age 40-69 years, family history of hypertension, personal history of dyslipidaemia and ischaemic heart disease, and care in a private hospital; in <6 hours: migraine, previous stroke, ischaemic heart disease, care in a private hospital, and family history of hypertension. Delayed hospital arrival was associated with lacunar stroke and alcoholism. Only 2.4% of patients underwent thrombolysis. Regardless of whether or not thrombolysis was performed, arrival time in <3 hours was associated with lower mortality at 3 and 6 months, and with fewer in-hospital complications. A high percentage of patients had short hospital arrival times; however, less than 3% underwent thrombolysis. Although many factors were associated with early hospital arrival, it is a priority to identify in-hospital barriers to performing thrombolysis. Copyright © 2013 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.
Distribution of EAS arrival times according to data of the EAS-1000 prototype array
Fomin, Yu A; Kulikov, G V; Solovyeva, V I; Sulakov, V P; Vedeneev, O V; Zotov, M Yu; Fomin, Yu. A.
2002-01-01
We have analysed arrival times of extensive air showers (EAS) registered with the EAS-1000 prototype array during the period from August, 1997 till February, 1999. Our analysis has revealed that though the vast majority of samples of consecutive time intervals between EAS arrival times obey the exponential distribution, there are sequences of showers that have another distribution and thus violate the homogeneity hypothesis. The search for correlation between such events and clusters of showers and events with big delays between arrival times was also carried out.
Behera, H S; Sahu, Sabyasachi; Bhoi, Sourav Kumar
2011-01-01
CPU being considered a primary computer resource, its scheduling is central to operating-system design. A thorough performance evaluation of various scheduling algorithms manifests that Round Robin Algorithm is considered as optimal in time shared environment because the static time is equally shared among the processes. We have proposed an efficient technique in the process scheduling algorithm by using dynamic time quantum in Round Robin. Our approach is based on the calculation of time quantum twice in single round robin cycle. Taking into consideration the arrival time, we implement the algorithm. Experimental analysis shows better performance of this improved algorithm over the Round Robin algorithm and the Shortest Remaining Burst Round Robin algorithm. It minimizes the overall number of context switches, average waiting time and average turn-around time. Consequently the throughput and CPU utilization is better.
Particle detection and non-detection in a quantum time of arrival measurement
Energy Technology Data Exchange (ETDEWEB)
Sombillo, Denny Lane B., E-mail: dsombillo@nip.upd.edu.ph; Galapon, Eric A.
2016-01-15
The standard time-of-arrival distribution cannot reproduce both the temporal and the spatial profile of the modulus squared of the time-evolved wave function for an arbitrary initial state. In particular, the time-of-arrival distribution gives a non-vanishing probability even if the wave function is zero at a given point for all values of time. This poses a problem in the standard formulation of quantum mechanics where one quantizes a classical observable and uses its spectral resolution to calculate the corresponding distribution. In this work, we show that the modulus squared of the time-evolved wave function is in fact contained in one of the degenerate eigenfunctions of the quantized time-of-arrival operator. This generalizes our understanding of quantum arrival phenomenon where particle detection is not a necessary requirement, thereby providing a direct link between time-of-arrival quantization and the outcomes of the two-slit experiment. -- Highlights: •The time-evolved position density is contained in the standard TOA distribution. •Particle may quantum mechanically arrive at a given point without being detected. •The eigenstates of the standard TOA operator are linked to the two-slit experiment.
A review of the decoherent histories approach to the arrival time problem in quantum theory
Yearsley, James M
2010-01-01
We review recent progress in understanding the arrival time problem in quantum mechanics, from the point of view of the decoherent histories approach to quantum theory. We begin by discussing the arrival time problem, focussing in particular on the role of the probability current in the expected classical solution. After a brief introduction to decoherent histories we review the use of complex potentials in the construction of appropriate class operators. We then discuss the arrival time problem for a particle coupled to an environment, and review how the arrival time probability can be expressed in terms of a POVM in this case. We turn finally to the question of decoherence of the corresponding histories, and we show that this can be achieved for simple states in the case of a free particle, and for general states for a particle coupled to an environment.
A fire management simulation model using stochastic arrival times
Eric L. Smith
1987-01-01
Fire management simulation models are used to predict the impact of changes in the fire management program on fire outcomes. As with all models, the goal is to abstract reality without seriously distorting relationships between variables of interest. One important variable of fire organization performance is the length of time it takes to get suppression units to the...
Arrival Times of Gravitational Radiation Peaks for Binary Inspiral
Price, Richard H
2016-01-01
Modeling of gravitational waves (GWs) from binary black hole inspiral brings together early post-Newtonian waveforms and late quasinormal ringing waveforms. Attempts to bridge the two limits without recourse to numerical relativity involve predicting the time of the peak GW amplitude. This prediction will require solving the question of why the peak of the "source," i.e., the peak of the binary angular velocity, does not correspond to the peak of the GW amplitude. We show here that this offset can be understood as due to the existence two distinct components of the radiation: the "direct" radiation analogous to that in flat spacetime, and "scattered" radiation associated with curved spacetime. The time dependence of these two components, and of their relative phases determines the location of the peak amplitude. We use a highly simplified model to clarify the twocomponent nature of the source, then demonstrate that the explanation is valid also for an extreme mass ratio binary inspiral.
Timing the arrival at 2340m altitude for aerobic performance
DEFF Research Database (Denmark)
Schuler, B; Thomsen, JJ; Gassmann, M
2007-01-01
This study tested the hypothesis that maximal oxygen uptake (VO2max) and performance increase upon altitude acclimatization at moderate altitude. Eight elite cyclists were studied at sea level, and after 1 (Day 1), 7 (Day 7), 14 (Day 14) and 21 (Day 21) days of exposure to 2340 m. Capillary blood...... samples were taken on these days before performing two consecutive maximal exercise trials. Acclimatization reased hemoglobin concentration and arterial oxygen content. On Day 1, VO2max and time to exhaustion (at 80% of sea-level maximal power output) decreased by 12.8% (P
A Fast-Time Study of Aircraft Reordering in Arrival Sequencing and Scheduling
Carr, Greg; Neuman, Frank; Tobias, Leonard (Technical Monitor)
1998-01-01
In order to ensure that the safe capacity of the terminal area is not exceeded, Air Traffic Management ATM often places restrictions on arriving flights transitioning from en route airspace to terminal airspace. This restriction of arrival traffic is commonly referred to as arrival flow management, and includes techniques such as metering, vectoring, fix-load balancing, and the imposition of miles-in-trail separations. These restrictions are enacted without regard for the relative priority which airlines may be placing on individual flights based on factors such as crew criticality, passenger connectivity, critical turn times, gate availability, on-time performance, fuel status, or runway preference. The development of new arrival flow management techniques which take into consideration priorities expressed by air carriers will likely reduce the economic impact of ATM restrictions on the airlines and lead to increased airline economic efficiency by allowing airlines to have greater control over their individual arrival banks of aircraft. NASA and the Federal Aviation Administration (FAA) have designed and developed a suite of software decision support tools (DSTs) collectively known as the Center TRACON Automation System (CTAS). One of these tools, the Traffic Management Advisor (TMA) is currently being used at the Fort Worth Air Route Traffic Control Center to perform arrival flow management of traffic into the Dallas/Fort Worth airport (DFW). The TMA is a time-based strategic planning tool that assists Traffic Management Coordinators (TMCs) and En Route Air Traffic Controllers in efficiently balancing arrival demand with airport capacity. The primary algorithm in the TMA is a real-time scheduler which generates efficient landing sequences and landing times for arrivals within about 200 no a. from touchdown. This scheduler will sequence aircraft so that they arrive in a first- come - first-served (FCFS) order. While FCFS sequencing establishes a fair order based
Tsunami arrival time detection system applicable to discontinuous time series data with outliers
Lee, Jun-Whan; Park, Sun-Cheon; Lee, Duk Kee; Lee, Jong Ho
2016-12-01
Timely detection of tsunamis with water level records is a critical but logistically challenging task because of outliers and gaps. Since tsunami detection algorithms require several hours of past data, outliers could cause false alarms, and gaps can stop the tsunami detection algorithm even after the recording is restarted. In order to avoid such false alarms and time delays, we propose the Tsunami Arrival time Detection System (TADS), which can be applied to discontinuous time series data with outliers. TADS consists of three algorithms, outlier removal, gap filling, and tsunami detection, which are designed to update whenever new data are acquired. After calibrating the thresholds and parameters for the Ulleung-do surge gauge located in the East Sea (Sea of Japan), Korea, the performance of TADS was discussed based on a 1-year dataset with historical tsunamis and synthetic tsunamis. The results show that the overall performance of TADS is effective in detecting a tsunami signal superimposed on both outliers and gaps.
Time-of-arrival distributions from position-momentum and energy-time joint measurements
Baute, A D; Muga, J G; Sala-Mayato, R
2000-01-01
The position-momentum quasi-distribution obtained from an Arthurs and Kelly joint measurement model is used to obtain indirectly an ``operational'' time-of-arrival (TOA) distribution following a quantization procedure proposed by Kocha\\'nski and Wódkiewicz [Phys. Rev. A 60, 2689 (1999)]. This TOA distribution is not time covariant. The procedure is generalized by using other phase-space quasi-distributions, and sufficient conditions are provided for time covariance that limit the possible phase-space quasi-distributions essentially to the Wigner function, which, however, provides a non-positive TOA quasi-distribution. These problems are remedied with a different quantization procedure which, on the other hand, does not guarantee normalization. Finally an Arthurs and Kelly measurement model for TOA and energy (valid also for arbitrary conjugate variables when one of the variables is bounded from below) is worked out. The marginal TOA distribution so obtained, a distorted version of Kijowski's distribution, is...
Scaling Behavior of the First Arrival Time of a Random-Walking Magnetic Domain
Energy Technology Data Exchange (ETDEWEB)
Im, M.-Y.; Lee, S.-H.; Kim, D.-H.; Fischer, P.; Shin, S.-C.
2008-02-04
We report a universal scaling behavior of the first arrival time of a traveling magnetic domain wall into a finite space-time observation window of a magneto-optical microscope enabling direct visualization of a Barkhausen avalanche in real time. The first arrival time of the traveling magnetic domain wall exhibits a nontrivial fluctuation and its statistical distribution is described by universal power-law scaling with scaling exponents of 1.34 {+-} 0.07 for CoCr and CoCrPt films, despite their quite different domain evolution patterns. Numerical simulation of the first arrival time with an assumption that the magnetic domain wall traveled as a random walker well matches our experimentally observed scaling behavior, providing an experimental support for the random-walking model of traveling magnetic domain walls.
An Exact Solution of the Gamma Ray Burst Arrival Time Analysis Problem
Indian Academy of Sciences (India)
S. Sinha
2002-03-01
An analytical solution of the GRB arrival time analysis is presented. The errors in the position of the GRB resulting from timing and position errors of different satellites are calculated. A simple method of cross-correlating gamma ray burst time-histories is discussed.
Uncertainty in Bus Arrival Time Predictions: Treating Heteroscedasticity With a Metamodel Approach
DEFF Research Database (Denmark)
O'Sullivan, Aidan; Pereira, Francisco Camara; Zhao, Jinhua
2016-01-01
Arrival time predictions for the next available bus or train are a key component of modern traveler information systems (TISs). A great deal of research has been conducted within the intelligent transportation system community in developing an assortment of different algorithms that seek to incre......Arrival time predictions for the next available bus or train are a key component of modern traveler information systems (TISs). A great deal of research has been conducted within the intelligent transportation system community in developing an assortment of different algorithms that seek...... sources. In this paper, we tackle the issue of uncertainty in bus arrival time predictions using an alternative approach. Rather than endeavor to develop a superior method for prediction, we take existing predictions from a TIS and treat the algorithm generating them as a black box. The presence...
Improvements of the shock arrival times at the Earth model STOA
Liu, H -L
2015-01-01
Prediction of the shocks' arrival times (SATs) at the Earth is very important for space weather forecast. There is a well-known SAT model, STOA, which is widely used in the space weather forecast. However, the shock transit time from STOA model usually has a relative large error compared to the real measurements. In addition, STOA tends to yield too much `yes' prediction, which causes a large number of false alarms. Therefore, in this work, we work on the modification of STOA model. First, we give a new method to calculate the shock transit time by modifying the way to use the solar wind speed in STOA model. Second, we develop new criteria for deciding whether the shock will arrive at the Earth with the help of the sunspot numbers and the angle distances of the flare events. It is shown that our work can improve the SATs prediction significantly, especially the prediction of flare events without shocks arriving at the Earth.
Canonical pairs, Spatially Confined Motion and the Quantum Time of Arrival Problem
Galapon, E A
2000-01-01
It has always been believed that no self-adjoint and canonical time of arrival operator can be constructed within the confines of standard quantum mechanics. In this Letter we demonstrate the otherwise. We do so by pointing out that there is no a priori reason in demanding that canonical pairs form a system of imprimitivities. We then proceed to show that a class of self-adjoint and canonical time of arrival (TOA) operators can be constructed for a spatially confined free particle. And then discuss the relatiobship between the non-self-adjointess of the TOA operator for the unconfined particle and the self-adjointness of the confined one.
Li, Quan-Lin
2010-01-01
In this paper, we provide a novel matrix-analytic approach for studying doubly exponential solution of randomized load balancing models (also known as the supermarket models) with Markovian arrival processes (MAPs) and PH service times. We describe the supermarket model as a system of differential vector equations, and obtain a close-form solution: doubly exponential structure, for the fixed point of the system of differential vector equations. Based on this, we show that the fixed point is decomposited into two groups of information under a product form: the arrival information and the service information, and indicate that the doubly exponential solution to the fixed point is not always unique for more general supermarket models. Furthermore, we analyze the exponential convergence of the current location of the supermarket model to its fixed point, and study the Lipschitz condition in the Kurtz Theorem under MAP arrivals and PH service times. This paper gains a new understanding how the workload probing can...
Managing truck arrivals with time windows to alleviate gate congestion at container terminals
DEFF Research Database (Denmark)
Chen, G.; Govindan, Kannan; Yang, Z.
2013-01-01
Long truck queues at gates often limit the efficiency of a container terminal and generate serious air pollution. To reduce the gate congestion, this paper proposes a method called'vessel dependent time windows (VDTWs)' to control truck arrivals, which involves partitioning truck entries into gro......Long truck queues at gates often limit the efficiency of a container terminal and generate serious air pollution. To reduce the gate congestion, this paper proposes a method called'vessel dependent time windows (VDTWs)' to control truck arrivals, which involves partitioning truck entries...... in the system. A conventional Genetic Algorithm (GA), a multi-society GA, and a hybrid algorithm using GA and Simulated Annealing are used to solve the optimization problem. A case study based on a real container terminal in China is performed, which shows the VDTWs method can flatten the truck arrivals...
Takahashi, Ryuichi
2017-01-01
In this study we demonstrate that general relativity predicts arrival time differences between gravitational wave (GW) and electromagnetic (EM) signals caused by the wave effects in gravitational lensing. The GW signals can arrive earlier than the EM signals in some cases if the GW/EM signals have passed through a lens, even if both signals were emitted simultaneously by a source. GW wavelengths are much larger than EM wavelengths; therefore, the propagation of the GWs does not follow the laws of geometrical optics, including the Shapiro time delay, if the lens mass is less than approximately 105 M⊙(f/Hz)‑1, where f is the GW frequency. The arrival time difference can reach ∼0.1 s (f/Hz)‑1 if the signals have passed by a lens of mass ∼8000 M⊙(f/Hz)‑1 with the impact parameter smaller than the Einstein radius; therefore, it is more prominent for lower GW frequencies. For example, when a distant supermassive black hole binary (SMBHB) in a galactic center is lensed by an intervening galaxy, the time lag becomes of the order of 10 days. Future pulsar timing arrays including the Square Kilometre Array and X-ray detectors may detect several time lags by measuring the orbital phase differences between the GW/EM signals in the SMBHBs. Gravitational lensing imprints a characteristic modulation on a chirp waveform; therefore, we can deduce whether a measured arrival time lag arises from intrinsic source properties or gravitational lensing. Determination of arrival time differences would be extremely useful in multimessenger observations and tests of general relativity.
First arrival time picking for microseismic data based on shearlet transform
Cheng, Yao; Li, Yue; Zhang, Chao
2017-03-01
Automatic identification and first arrival time picking of microseismic data play an important role in microseismic monitoring technology, and it is the precondition for real-time microseismic hypocenter location. This paper presents a novel first arrival time picking method based on shearlet transform (ST), which aims to get satisfactory results in low signal-to-noise ratio data. The ST is used to decompose noisy microseismic data. By the coefficient differences between the signal and noise at fine scales, the signal points can be preliminarily selected from the noise. To further improve the accuracy of the signal recognition, a correction to the selected signal points is made by utilizing the scale correlation between adjacent scales. The realization of the correction depends on the distances between the signal points at one scale and those at its adjacent scale. After the correction, the moment of the first identified signal point is the first arrival time. This proposed method can produce a superior performance in the accuracy of the first arrival time picking, compared with the other methods, as demonstrated using synthetic and field microseismic data. The actual picking performance of the method is further verified by receiver operating characteristic curves.
Wahl, Michael; Leifgen, Matthias; Berlin, Michael; Röhlicke, Tino; Rahn, Hans-Jürgen; Benson, Oliver
2011-04-01
We report the implementation of a quantum random number generator based on photon arrival times. Due to fast and high resolution timing we are able to generate the highest bitrate of any current generator based on photon arrival times. Bias in the raw data due to the exponential distribution of the arrival times is removed by postprocessing which is directly integrated in the field programmable logic of the timing electronics.
Borcea, Liliana; Tsogka, Chrysoula
2016-01-01
We study detection and imaging of small reflectors in heavy clutter, using an array of transducers that emits and receives sound waves. Heavy clutter means that multiple scattering of the waves in the heterogeneous host medium is strong and overwhelms the arrivals from the small reflectors. Building on the adaptive time-frequency filter of [1], we propose a robust method for detecting the direction of arrival of the direct echoes from the small reflectors, and suppressing the unwanted clutter backscatter. This improves the resolution of imaging. We illustrate the performance of the method with realistic numerical simulations in a non-destructive testing setup.
Correlations between pulsed X-ray flux and radio arrival time in the Vela pulsar
Lommen, A N; Gwinn, C; Arzoumanian, Z; Harding, A; Strickman, M S; Dodson, R; McCulloch, P; Moffett, D
2007-01-01
We report the results of simultaneous observations of the Vela pulsar in X-rays and radio from the RXTE satellite and the Mount Pleasant Radio Observatory in Tasmania. We sought correlations between the Vela's X-ray and radio flux densities and radio arrival times on a pulse by pulse basis. We found significantly higher flux density in Vela's main X-ray peak during radio pulses that arrived early. This excess flux shifts to the 'trough' following the 2nd X-ray peak during radio pulses that arrive later. We suggest that the mechanism producing the radio pulses is intimately connected to the mechanism producing X-rays. Current models using resonant absorption in the outer magnetosphere as a cause of the radio emission, and less directly of the X-ray emission, are explored as a possible explanation for the correlation.
Correlation between X-ray Lightcurve Shape and Radio Arrival Time in the Vela Pulsar
Lommen, A; Gwinn, C; Arzoumanian, Z; Harding, A; Strickman, M S; Dodson, R; McCulloch, P; Moffett, D
2006-01-01
We report the results of simultaneous observations of the Vela pulsar in X-rays and radio from the RXTE satellite and the Mount Pleasant Radio Observatory in Tasmania. We sought correlations between the Vela's X-ray emission and radio arrival times on a pulse by pulse basis. At a confidence level of 99.8% we have found significantly higher flux density in Vela's main X-ray peak during radio pulses that arrived early. This excess flux shifts to the 'trough' following the 2nd X-ray peak during radio pulses that arrive later. Our results suggest that the mechanism producing the radio pulses is intimately connected to the mechanism producing X-rays. Current models using resonant absorption of radio emission in the outer magnetosphere as a cause of the X-ray emission are explored as a possible explanation for the correlation.
Refinement of arrival-time picks using a cross-correlation based workflow
Akram, Jubran; Eaton, David W.
2016-12-01
We propose a new iterative workflow based on cross-correlation for improved arrival-time picking on microseismic data. In this workflow, signal-to-noise ratio (S/N) and polarity weighted stacking are used to minimize the effect of S/N and polarity fluctuations on the pilot waveform computation. We use an exhaustive search technique for polarity estimation through stack power maximization. We use pseudo-synthetic and real microseismic data from western Canada in order to demonstrate the effectiveness of proposed workflow relative to Akaike information criterion (AIC) and a previously published cross-correlation based method. The pseudo-synthetic microseismic waveforms are obtained by introducing Gaussian noise and polarity fluctuations into waveforms from a high S/N microseismic event. We find that the cross-correlation based approaches yield more accurate arrival-time picks as compared to AIC for low S/N waveforms. AIC is not affected by waveform polarities as it works on individual receiver levels whereas the accuracy of existing cross-correlation method decreases in spite of using envelope correlation. We show that our proposed workflow yields better and consistent arrival-time picks regardless of waveform amplitude and polarity variations within the receiver array. After refinement, the initial arrival-time picks are located closer to the best estimated manual picks.
Takahashi, Ryuichi
2016-01-01
In this study, we demonstrate that general relativity predicts arrival time differences between gravitational wave (GW) and electromagnetic (EM) signals caused by the wave effects in gravitational lensing. The GW signals can arrive $earlier$ than the EM signals in some cases if the GW/EM signals have passed through a lens, even if both signals were emitted simultaneously by a source. GW wavelengths are much larger than EM wavelengths; therefore, the propagation of the GWs does not follow the laws of geometrical optics, including the Shapiro time delay, if the lens mass is less than approximately $10^5 {\\rm M}_\\odot (f/{\\rm Hz})^{-1}$, where $f$ is the GW frequency. The arrival time difference can reach $\\sim 0.1 \\, {\\rm s} \\, (f/{\\rm Hz})^{-1}$; therefore, it is more prominent for lower GW frequencies. Gravitational lensing imprints a characteristic modulation on a chirp waveform; therefore, we can deduce whether a measured arrival time lag arises from intrinsic source properties or gravitational lensing. Det...
Design of a Normal Conducting Cavity for Arrival Time Stabilization at FLASH
Fakhari, M.; Pfeiffer, S.; Schlarb, H.; Rossbach, J.
2016-01-01
The long range longitudinal wakefield calculation results are reported to investigate the cavity performance for multibeam operation up to 3 MHz bunch repetition rate. The results declare that the influence of the long range wakefield on the arrival time jitter is less than 1 fs.
Galapon, E A
2001-01-01
We raise the problem of constructing quantum observables that have classical counterparts without quantization. Specifically we seek to define and motivate a solution to the quantum-classical correspondence problem independent from quantization and discuss the general insufficiency of prescriptive quantization, particularly the Weyl quantization. We demonstrate our points by constructing time of arrival operators without quantization and from these recover their classical counterparts.
Directory of Open Access Journals (Sweden)
Moon Ho Lee
2008-01-01
Full Text Available A multiserver queueing model that does not have a buffer but has batch arrival of customers is considered. In contrast to the standard batch arrival, in which the entire batch arrives at the system during a single epoch, we assume that the customers of a batch (flow arrive individually in exponentially distributed times. The service time is exponentially distributed. Flows arrive according to a stationary Poisson arrival process. The flow size distribution is geometric. The number of flows that can be simultaneously admitted to the system is under control. The loss of any customer from an admitted flow, with a fixed probability, implies termination of the flow arrival. Analysis of the sojourn time and loss probability of an arbitrary flow is performed.
A New Prediction Method for the Arrival Time of Interplanetary Shocks
Feng, Xueshang; Zhao, Xinhua
2006-10-01
Solar transient activities such as solar flares, disappearing filaments, and coronal mass ejections (CMEs) are solar manifestations of interplanetary (IP) disturbances. Forecasting the arrival time at the near Earth space of the associated interplanetary shocks following these solar disturbances is an important aspect in space weather forecasting because the shock arrival usually marks the geomagnetic storm sudden commencement (SSC) when the IMF Bz component is appropriately southward and/or the solar wind dynamic pressure behind the shock is sufficiently large. Combining the analytical study for the propagation of the blast wave from a point source in a moving, steady-state, medium with variable density (wei, 1982; wei and dryer 1991) with the energy estimation method in the ISPM model (smith and dryer 1990, 1995), we present a new shock propagation model (called SPM below) for predicting the arrival time of interplanetary shocks at Earth. The duration of the X-ray flare, the initial shock speed and the total energy of the transient event are used for predicting the arrival of the associated shocks in our model. Especially, the background speed, i.e., the convection effect of the solar wind is considered in this model. Applying this model to 165 solar events during the periods of January 1979 to October 1989 and February 1997 to August 2002, we found that our model could be practically equivalent to the prevalent models of STOA, ISPM and HAFv.2 in forecasting the shock arrival time. The absolute error in the transit time in our model is not larger than those of the other three models for the same sample events. Also, the prediction test shows that the relative error of our model is ≤10% for 27.88% of all events, ≤30% for 71.52%, and ≤50% for 85.46%, which is comparable to the relative errors of the other models. These results might demonstrate a potential capability of our model in terms of real-time forecasting.
High-speed quantum-random number generation by continuous measurement of arrival time of photons
Yan, Qiurong; Zhao, Baosheng; Hua, Zhang; Liao, Qinghong; Yang, Hao
2015-07-01
We demonstrate a novel high speed and multi-bit optical quantum random number generator by continuously measuring arrival time of photons with a common starting point. To obtain the unbiased and post-processing free random bits, the measured photon arrival time is converted into the sum of integral multiple of a fixed period and a phase time. Theoretical and experimental results show that the phase time is an independent and uniform random variable. A random bit extraction method by encoding the phase time is proposed. An experimental setup has been built and the unbiased random bit generation rate could reach 128 Mb/s, with random bit generation efficiency of 8 bits per detected photon. The random numbers passed all tests in the statistical test suite.
Directory of Open Access Journals (Sweden)
Syed Asif Ali Shah
2012-01-01
Full Text Available Flow time analysis is a powerful concept to analyze the flow time of any arriving customer in any system at any instant. A load management mechanism can be employed very effectively in any queueing system by utilizing a system which provides probability of dual service rate. In this paper, we develop and demonstrate the flow and service processes transition diagram to determine the flow time of a customer in a load management late arrival state dependent finite discrete time queueing system with dual service rate where customers are hypogeometrically distributed. We compute the probability mass function of each starting state and total probability mass function. The obtained analytical results are validated with simulation results for varying values of arrival and service probabilities.
An Arrival and Departure Time Predictor for Scheduling Communication in Opportunistic IoT
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Riccardo Pozza
2016-11-01
Full Text Available In this article, an Arrival and Departure Time Predictor (ADTP for scheduling communication in opportunistic Internet of Things (IoT is presented. The proposed algorithm learns about temporal patterns of encounters between IoT devices and predicts future arrival and departure times, therefore future contact durations. By relying on such predictions, a neighbour discovery scheduler is proposed, capable of jointly optimizing discovery latency and power consumption in order to maximize communication time when contacts are expected with high probability and, at the same time, saving power when contacts are expected with low probability. A comprehensive performance evaluation with different sets of synthetic and real world traces shows that ADTP performs favourably with respect to previous state of the art. This prediction framework opens opportunities for transmission planners and schedulers optimizing not only neighbour discovery, but the entire communication process.
An Arrival and Departure Time Predictor for Scheduling Communication in Opportunistic IoT.
Pozza, Riccardo; Georgoulas, Stylianos; Moessner, Klaus; Nati, Michele; Gluhak, Alexander; Krco, Srdjan
2016-11-04
In this article, an Arrival and Departure Time Predictor (ADTP) for scheduling communication in opportunistic Internet of Things (IoT) is presented. The proposed algorithm learns about temporal patterns of encounters between IoT devices and predicts future arrival and departure times, therefore future contact durations. By relying on such predictions, a neighbour discovery scheduler is proposed, capable of jointly optimizing discovery latency and power consumption in order to maximize communication time when contacts are expected with high probability and, at the same time, saving power when contacts are expected with low probability. A comprehensive performance evaluation with different sets of synthetic and real world traces shows that ADTP performs favourably with respect to previous state of the art. This prediction framework opens opportunities for transmission planners and schedulers optimizing not only neighbour discovery, but the entire communication process.
The NANOGrav Nine-Year Data Set: Excess Noise in Millisecond Pulsar Arrival Times
Lam, M T; Chatterjee, S; Arzoumanian, Z; Crowter, K; Demorest, P B; Dolch, T; Ellis, J A; Ferdman, R D; Fonseca, E; Gonzalez, M E; Jones, G; Jones, M L; Levin, L; Madison, D R; McLaughlin, M A; Nice, D J; Pennucci, T T; Ransom, S M; Shannon, R M; Siemens, X; Stairs, I H; Stovall, K; Swiggum, J K; Zhu, W W
2016-01-01
Gravitational wave astronomy using a pulsar timing array requires high-quality millisecond pulsars, correctable interstellar propagation delays, and high-precision measurements of pulse times of arrival. Here we identify noise in timing residuals that exceeds that predicted for arrival time estimation for millisecond pulsars observed by the North American Nanohertz Observatory for Gravitational Waves. We characterize the excess noise using variance and structure function analyses. We find that 26 out of 37 pulsars show inconsistencies with a white-noise-only model based on the short timescale analysis of each pulsar and we demonstrate that the excess noise has a red power spectrum for 15 pulsars. We also decompose the excess noise into chromatic (radio-frequency-dependent) and achromatic components. Associating the achromatic red-noise component with spin noise and including additional power-spectrum-based estimates from the literature, we estimate a scaling law in terms of spin parameters (frequency and freq...
A Detailed Study on the Equal Arrival Time Surface Effect in Gamma-Ray Burst Afterglows
Institute of Scientific and Technical Information of China (English)
Yong-Feng Huang; Ye Lu; Anna Yuen Lam Wong; Kwong Sang Cheng
2007-01-01
Due to the relativistic motion of gamma-ray burst remnant and its deceleration in the circumburst medium,the equal arrival time surfaces at any moment are not spherical,rather,they are distorted ellipsoids.This will leave some imprints in the afterglows.We study the effect of equal arrival time surfaces numerically for various circumstances,i.e., isotropic fireballs,collimated jets,density jumps and energy injection events.For each case,a direct comparison is made between including and not including the effect.For isotropic fireballs and jets viewed on axis,the effect slightly hardens the spectra and postpones the peak time of the afterglows,but does not change the shapes of the spectra and light curves significantly.In the cases of a density jump or an energy injection,the effect smears out the variations in the afterglows markedly.
Breaking the fixed-arrival-time restriction in reaching movements of neural prosthetic devices.
Srinivasan, Lakshminarayan; da Silva, Marco
2011-06-01
We routinely generate reaching arm movements to function independently. For paralyzed users of upper extremity neural prosthetic devices, flexible, high-performance reaching algorithms will be critical to restoring quality-of-life. Previously, algorithms called real-time reach state equations (RSE) were developed to integrate the user's plan and execution-related neural activity to drive reaching movements to arbitrary targets. Preliminary validation under restricted conditions suggested that RSE might yield dramatic performance improvements. Unfortunately, real-world applications of RSE have been impeded because the RSE assumes a fixed, known arrival time. Recent animal-based prototypes attempted to break the fixed-arrival-time assumption by proposing a standard model (SM) that instead restricted the user's movements to a fixed, known set of targets. Here, we leverage general purpose filter design (GPFD) to break both of these critical restrictions, freeing the paralyzed user to make reaching movements to arbitrary target sets with various arrival times and definitive stopping. In silico validation predicts that the new approach, GPFD-RSE, outperforms the SM while offering greater flexibility. We demonstrate the GPFD-RSE against SM in the simulated control of an overactuated 3-D virtual robotic arm with a real-time inverse kinematics engine.
Two-Step Time of Arrival Estimation for Pulse-Based Ultra-Wideband Systems
Directory of Open Access Journals (Sweden)
H. Vincent Poor
2008-05-01
Full Text Available In cooperative localization systems, wireless nodes need to exchange accurate position-related information such as time-of-arrival (TOA and angle-of-arrival (AOA, in order to obtain accurate location information. One alternative for providing accurate position-related information is to use ultra-wideband (UWB signals. The high time resolution of UWB signals presents a potential for very accurate positioning based on TOA estimation. However, it is challenging to realize very accurate positioning systems in practical scenarios, due to both complexity/cost constraints and adverse channel conditions such as multipath propagation. In this paper, a two-step TOA estimation algorithm is proposed for UWB systems in order to provide accurate TOA estimation under practical constraints. In order to speed up the estimation process, the first step estimates a coarse TOA of the received signal based on received signal energy. Then, in the second step, the arrival time of the first signal path is estimated by considering a hypothesis testing approach. The proposed scheme uses low-rate correlation outputs and is able to perform accurate TOA estimation in reasonable time intervals. The simulation results are presented to analyze the performance of the estimator.
Dead on Arrival: Adapting Games to Finish at a Given Time or Location
von Öhsen, Arne; Loviscach, Jörn
Casual and other games often serve as time-killing applications, be it on the commuter train or in the back seat of a shared car. When one arrives at the destination, the game has to be interrupted or aborted, which is annoying or even frustrating. Hence, we propose to continuously adapt the game’s level of difficulty to the estimated remaining time to arrival. This can be preset as a number of minutes or can continuously be estimated from the player’s position in relation to a predefined destination. Our dungeon-style prototype is based on an automated engine for content placement and can also make use of GPS data. We report on preliminary results from user tests.
AIMBAT: A Python/Matplotlib Tool for Measuring Teleseismic Arrival Times
Lou, X.; van der Lee, S.; Lloyd, S.
2013-12-01
Python is an open-source, platform-independent, and object-oriented scripting language. It became more popular in the seismologist community since the appearance of ObsPy (Beyreuther et al. 2010, Megies et al. 2011), which provides a powerful framework for seismic data access and processing. This study introduces a new Python-based tool named AIMBAT (Automated and Interactive Measurement of Body-wave Arrival Times) for measuring teleseismic body-wave arrival times on large-scale seismic event data (Lou et al. 2013). Compared to ObsPy, AIMBAT is a lighter tool that is more focused on a particular aspect of seismic data processing. It originates from the widely used MCCC (Multi-Channel Cross-Correlation) method developed by VanDecar and Crosson (1990). On top of the original MCCC procedure, AIMBAT is automated in initial phase picking and is interactive in quality control. The core cross-correlation function is implemented in Fortran to boost up performance in addition to Python. The GUI (graphical user interface) of AIMBAT depends on Matplotlib's GUI-neutral widgets and event-handling API. A number of sorting and (de)selecting options are designed to facilitate the quality control of seismograms. By using AIMBAT, both relative and absolute teleseismic body-wave arrival times are measured. AIMBAT significantly improves efficiency and quality of the measurements. User interaction is needed only to pick the target phase arrival and to set a time window on the array stack. The package is easy to install and use, open-source, and is publicly available. Graphical user interface of AIMBAT.
Li,Quan-Lin; Lui, John C. S.
2010-01-01
In this paper, we provide a novel matrix-analytic approach for studying doubly exponential solutions of randomized load balancing models (also known as supermarket models) with Markovian arrival processes (MAPs) and phase-type (PH) service times. We describe the supermarket model as a system of differential vector equations by means of density dependent jump Markov processes, and obtain a closed-form solution with a doubly exponential structure to the fixed point of the system of differential...
Li, Quan-Lin; Lui, John C. S.
2010-01-01
In this paper, we provide a novel matrix-analytic approach for studying doubly exponential solutions of randomized load balancing models (also known as supermarket models) with Markovian arrival processes (MAPs) and phase-type (PH) service times. We describe the supermarket model as a system of differential vector equations by means of density dependent jump Markov processes, and obtain a closed-form solution with a doubly exponential structure to the fixed point of the system of differential...
Punctuality of Intercity Trains and Passengers’ Perspective towards Arrival Time Delay
Directory of Open Access Journals (Sweden)
Nur Sabahiah Abdul Sukor
2013-02-01
Full Text Available Systematic railway scheduling is important to encourage the public to choose rail transit system as their preferred transportation mode. However, the punctuality of trains still becomes the main problem in railway operation service in Malaysia. The purpose of this study is to determine the punctuality and arrival time of Keretapi Tanah Melayu Berhad’s (KTMB intercity trains at Kluang Railway Station. The study was conducted at Kluang Railway Station by using observation and survey methods. The observation study was focused on several types of intercity trains where the arrival times of the trains were recorded and compared with the train schedule. Next, the survey was aimed to obtain passengers’ perspective towards the punctuality of the trains. As a result from the observation, the average arrival time delay for all observed trains was around 10 min. In addition, most of the passengers responded that the punctuality of the intercity trains was poor and this punctuality issue has to be improved. The results obtained from this study are useful to enhance the train services.
Energy Technology Data Exchange (ETDEWEB)
Roussel-Dupre, R.; Symbalisty, E.; Fox, C.; and Vanderlinde, O.
2009-08-01
The location of a radiating source can be determined by time-tagging the arrival of the radiated signal at a network of spatially distributed sensors. The accuracy of this approach depends strongly on the particular time-tagging algorithm employed at each of the sensors. If different techniques are used across the network, then the time tags must be referenced to a common fiducial for maximum location accuracy. In this report we derive the time corrections needed to temporally align leading-edge, time-tagging techniques with peak-picking algorithms. We focus on broadband radio frequency (RF) sources, an ionospheric propagation channel, and narrowband receivers, but the final results can be generalized to apply to any source, propagation environment, and sensor. Our analytic results are checked against numerical simulations for a number of representative cases and agree with the specific leading-edge algorithm studied independently by Kim and Eng (1995) and Pongratz (2005 and 2007).
Petzoldt, Tibor
2016-10-01
Crashes at railway level crossings are a key problem for railway operations. It has been suggested that a potential explanation for such crashes might lie in a so-called size speed bias, which describes the phenomenon that observers underestimate the speed of larger objects, such as aircraft or trains. While there is some evidence that this size speed bias indeed exists, it is somewhat at odds with another well researched phenomenon, the size arrival effect. When asked to judge the time it takes an approaching object to arrive at a predefined position (time to arrival, TTA), observers tend to provide lower estimates for larger objects. In that case, road users' crossing decisions when confronted with larger vehicles should be rather conservative, which has been confirmed in multiple studies on gap acceptance. The aim of the experiment reported in this paper was to clarify the relationship between size speed bias and size arrival effect. Employing a relative judgment task, both speed and TTA estimates were assessed for virtual depictions of a train and a truck, using a car as a reference to compare against. The results confirmed the size speed bias for the speed judgments, with both train and truck being perceived as travelling slower than the car. A comparable bias was also present in the TTA estimates for the truck. In contrast, no size arrival effect could be found for the train or the truck, neither in the speed nor the TTA judgments. This finding is inconsistent with the fact that crossing behaviour when confronted with larger vehicles appears to be consistently more conservative. This discrepancy might be interpreted as an indication that factors other than perceived speed or TTA play an important role for the differences in gap acceptance between different types of vehicles.
Congestion Behavior under Uncertainty on Morning Commute with Preferred Arrival Time Interval
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LingLing Xiao
2014-01-01
Full Text Available This paper extends the bottleneck model to study congestion behavior of morning commute with flexible work schedule. The proposed model assumes a stochastic bottleneck capacity which follows a uniform distribution and homogeneous commuters who have the same preferred arrival time interval. The commuters are fully aware of the stochastic properties of travel time and schedule delay distributions at all departure times that emerge from day-to-day capacity variations. The commuters’ departure time choice follows user equilibrium (UE principle in terms of the expected trip cost. Analytical and numerical solutions of this model are provided. The equilibrium departure time patterns are examined which show that the stochastic capacity increases the mean trip cost and lengthens the rush hour. The adoption of flexitime results in less congestion and more efficient use of bottleneck capacity than fixed-time work schedule. The longer the flexi-time interval is, the more uniformly distributed the departure times are.
Anderson, R. E.; Frey, R. L.; Lewis, J. R.
1980-01-01
Position surveillance using one active ranging/communication satellite and the time-of-arrival of signals from an independent satellite was shown to be feasible and practical. A towboat on the Mississippi River was equipped with a tone-code ranging transponder and a receiver tuned to the timing signals of the GOES satellite. A similar transponder was located at the office of the towing company. Tone-code ranging interrogations were transmitted from the General Electric Earth Station Laboratory through ATS-6 to the towboat and to the ground truth transponder office. Their automatic responses included digital transmissions of time-of-arrival measurements derived from the GOES signals. The Earth Station Laboratory determined ranges from the satellites to the towboat and computed position fixes. The ATS-6 lines-of-position were more precise than 0.1 NMi, 1 sigma, and the GOES lines-of-position were more precise than 1.6 NMi, 1 sigma. High quality voice communications were accomplished with the transponders using a nondirectional antenna on the towboat. The simple and effective surveillance technique merits further evaluation using operational maritime satellites.
Ready...go: Amplitude of the FMRI signal encodes expectation of cue arrival time.
Directory of Open Access Journals (Sweden)
Xu Cui
2009-08-01
Full Text Available What happens when the brain awaits a signal of uncertain arrival time, as when a sprinter waits for the starting pistol? And what happens just after the starting pistol fires? Using functional magnetic resonance imaging (fMRI, we have discovered a novel correlate of temporal expectations in several brain regions, most prominently in the supplementary motor area (SMA. Contrary to expectations, we found little fMRI activity during the waiting period; however, a large signal appears after the "go" signal, the amplitude of which reflects learned expectations about the distribution of possible waiting times. Specifically, the amplitude of the fMRI signal appears to encode a cumulative conditional probability, also known as the cumulative hazard function. The fMRI signal loses its dependence on waiting time in a "countdown" condition in which the arrival time of the go cue is known in advance, suggesting that the signal encodes temporal probabilities rather than simply elapsed time. The dependence of the signal on temporal expectation is present in "no-go" conditions, demonstrating that the effect is not a consequence of motor output. Finally, the encoding is not dependent on modality, operating in the same manner with auditory or visual signals. This finding extends our understanding of the relationship between temporal expectancy and measurable neural signals.
Ready...go: Amplitude of the FMRI signal encodes expectation of cue arrival time.
Cui, Xu; Stetson, Chess; Montague, P Read; Eagleman, David M
2009-08-01
What happens when the brain awaits a signal of uncertain arrival time, as when a sprinter waits for the starting pistol? And what happens just after the starting pistol fires? Using functional magnetic resonance imaging (fMRI), we have discovered a novel correlate of temporal expectations in several brain regions, most prominently in the supplementary motor area (SMA). Contrary to expectations, we found little fMRI activity during the waiting period; however, a large signal appears after the "go" signal, the amplitude of which reflects learned expectations about the distribution of possible waiting times. Specifically, the amplitude of the fMRI signal appears to encode a cumulative conditional probability, also known as the cumulative hazard function. The fMRI signal loses its dependence on waiting time in a "countdown" condition in which the arrival time of the go cue is known in advance, suggesting that the signal encodes temporal probabilities rather than simply elapsed time. The dependence of the signal on temporal expectation is present in "no-go" conditions, demonstrating that the effect is not a consequence of motor output. Finally, the encoding is not dependent on modality, operating in the same manner with auditory or visual signals. This finding extends our understanding of the relationship between temporal expectancy and measurable neural signals.
The Effect of Integration Policies on the Time until Regular Employment of Newly Arrived Immigrants:
DEFF Research Database (Denmark)
Clausen, Jens; Heinesen, Eskil; Hummelgaard, Hans
We analyse the effect of active labour-market programmes on the hazard rate into regular employment for newly arrived immigrants using the timing-of-events duration model. We take account of language course participation and progression in destination country language skills. We use rich...... administrative data from Denmark. We find substantial lock-in effects of participation in active labour-market programmes. Post programme effects on the hazard rate to regular employment are significantly positive for wage subsidy programmes, but not for other types of programmes. For language course...... participants, improvement in language proficiency has significant and substantial positive effects on the hazard rate to employment....
Precise and accurate train run data: Approximation of actual arrival and departure times
DEFF Research Database (Denmark)
Richter, Troels; Landex, Alex; Andersen, Jonas Lohmann Elkjær
trains have come to a halt nor when trains have set in motion again. Thus the measurements are inaccurate and do not express the experience of the passengers. A commonly accepted method to make this measurement possible is to construct a correction function to the track circuit based measurement....... This function estimates the inaccuracy or bias of the measurement and thus which offset is needed to approximate the actual arrival and departure times. The development of such a function is described in this paper. The development is based on international best practices combined with what is technically...
The Effect of Integration Policies on the Time until Regular Employment of Newly Arrived Immigrants:
DEFF Research Database (Denmark)
Clausen, Jens; Heinesen, Eskil; Hummelgaard, Hans
We analyse the effect of active labour-market programmes on the hazard rate into regular employment for newly arrived immigrants using the timing-of-events duration model. We take account of language course participation and progression in destination country language skills. We use rich...... administrative data from Denmark. We find substantial lock-in effects of participation in active labour-market programmes. Post programme effects on the hazard rate to regular employment are significantly positive for wage subsidy programmes, but not for other types of programmes. For language course...... participants, improvement in language proficiency has significant and substantial positive effects on the hazard rate to employment....
Statistical Properties of Inter-arrival Times Distribution in Social Tagging Systems
Capocci, Andrea; Servedio, Vito D P; Loreto, Vittorio
2012-01-01
Folksonomies provide a rich source of data to study social patterns taking place on the World Wide Web. Here we study the temporal patterns of users' tagging activity. We show that the statistical properties of inter-arrival times between subsequent tagging events cannot be explained without taking into account correlation in users' behaviors. This shows that social interaction in collaborative tagging communities shapes the evolution of folksonomies. A consensus formation process involving the usage of a small number of tags for a given resources is observed through a numerical and analytical analysis of some well-known folksonomy datasets.
Prediction of the Critical Curvature for LX-17 with the Time of Arrival Data from DNS
Energy Technology Data Exchange (ETDEWEB)
Yao, Jin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fried, Laurence E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Moss, William C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2017-01-10
We extract the detonation shock front velocity, curvature and acceleration from time of arrival data measured at grid points from direct numerical simulations of a 50mm rate-stick lit by a disk-source, with the ignition and growth reaction model and a JWL equation of state calibrated for LX-17. We compute the quasi-steady (D, κ) relation based on the extracted properties and predicted the critical curvatures of LX-17. We also proposed an explicit formula that contains the failure turning point, obtained from optimization for the (D, κ) relation of LX-17.
A PERISHABLE INVENTORY SYSTEM WITH SERVICE FACILITIES, MAP ARRIVALS AND PH - SERVICE TIMES
Institute of Scientific and Technical Information of China (English)
Paul MANUEL; B.SIVAKUMAR; G.ARIVARIGNAN
2007-01-01
We consider a continuous review perishable (s,S) inventory system with a service facility consisting of a waiting hall of finite capacity and a single server.We assume two types of customers,ordinary and negative,arrive according to a Markovian Arrival Process (MAP).An ordinary customer joins the queue and a negative customer instead of joining the queue removes one ordinary customer from the queue.The removal rule adopted in this paper is RCE (removal of a customer from the end).The individual customer's unit demand is satisfied after a random time of service which is assumed to have a phase-type distribution.The life time of each item and the lead time of the reorders have been assumed to be independent exponential distributions.The joint probability distribution of the number of customers in the system and the inventory level is obtained for the steady state case.Various stationary system performance measures are computed and the total expected cost rate is calculated.The results are illustrated numerically.
Sanders, Geoff; Sinclair, Kamila
2011-12-01
We report two Internet studies that investigated sex differences in the accuracy and precision of judging time to arrival. We used accuracy to mean the ability to match the actual time to arrival and precision to mean the consistency with which each participant made their judgments. Our task was presented as a computer game in which a toy UFO moved obliquely towards the participant through a virtual three-dimensional space on route to a docking station. The UFO disappeared before docking and participants pressed their space bar at the precise moment they thought the UFO would have docked. Study 1 showed it was possible to conduct quantitative studies of spatiotemporal judgments in virtual reality via the Internet and confirmed reports that men are more accurate because women underestimate, but found no difference in precision measured as intra-participant variation. Study 2 repeated Study 1 with five additional presentations of one condition to provide a better measure of precision. Again, men were more accurate than women but there were no sex differences in precision. However, within the coincidence-anticipation timing (CAT) literature, of those studies that report sex differences, a majority found that males are both more accurate and more precise than females. Noting that many CAT studies report no sex differences, we discuss appropriate interpretations of such null findings. While acknowledging that CAT performance may be influenced by experience we suggest that the sex difference may have originated among our ancestors with the evolutionary selection of men for hunting and women for gathering.
Energy Technology Data Exchange (ETDEWEB)
Cho, Seung Hyun; Kwon, Hyu Sang; Ahn, Bong Young; Lee, Seung Seok [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)
2008-12-15
Guided wave technology is advantageous for fast inspection of pipe wall thinning since the guided wave propagates long distance. In this investigation, the method to evaluate gradual wall thinning in a pipe based on the arrival time delay with magnetostrictive patch transducers is presented. Low frequency A0 Lamb waves were generated and measured by the present transducer and it was applied to arrival time delay measurement experiments on a test pipe having gradual wall thinnings artificially manufactured. From experiments, consistent results that wall thinning increases the arrival time delay of A0 waves were obtained. Consequently, the feasibility of the magnetostrictive patch transducers to evaluate wall thinning was verified
CME Arrival-time Validation of Real-time WSA-ENLIL+Cone Simulations at the CCMC/SWRC
Wold, A. M.; Mays, M. L.; Taktakishvili, A.; Jian, L.; Odstrcil, D.; MacNeice, P. J.
2016-12-01
The Wang-Sheeley-Arge (WSA)-ENLIL+Cone model is used extensively in space weather operations worldwide to model CME propagation, as such it is important to assess its performance. We present validation results of the WSA-ENLIL+Cone model installed at the Community Coordinated Modeling Center (CCMC) and executed in real-time by the CCMC/Space Weather Research Center (SWRC). The SWRC is a CCMC sub-team that provides space weather services to NASA robotic mission operators and science campaigns, and also prototypes new forecasting models and techniques. CCMC/SWRC uses the WSA-ENLIL+Cone model to predict CME arrivals at NASA missions throughout the inner heliosphere. In this work we compare model predicted CME arrival-times to in-situ ICME shock observations near Earth (ACE, Wind), STEREO-A and B for simulations completed between March 2010 - July 2016 (over 1500 runs). We report hit, miss, false alarm, and correct rejection statistics for all three spacecraft. For hits we compute the bias, RMSE, and average absolute CME arrival time error, and the dependence of these errors on CME input parameters. We compare the predicted geomagnetic storm strength (Kp index) to the CME arrival time error for Earth-directed CMEs. The predicted Kp index is computed using the WSA-ENLIL+Cone plasma parameters at Earth with a modified Newell et al. (2007) coupling function. We also explore the impact of the multi-spacecraft observations on the CME parameters used initialize the model by comparing model validation results before and after the STEREO-B communication loss (since September 2014) and STEREO-A side-lobe operations (August 2014-December 2015). This model validation exercise has significance for future space weather mission planning such as L5 missions.
FINITE-TIME RUIN PROBABILITY WITH NQD DOMINATED VARYING-TAILED CLAIMS AND NLOD INTER-ARRIVAL TIMES
Institute of Scientific and Technical Information of China (English)
Jingzhi LI; Kaiyong WANG; Yuebao WANG
2009-01-01
In 2007, Chen and Ng investigated infinite-time ruin probability with constant interest force and negatively quadrant dependent and extended regularly varying-tailed claims. Following this work, the authors obtain a weakly asymptotic equivalent formula for the finite-time and infinite-time ruin probability with constant interest force, negatively quadrant dependent, and dominated varying-tailed claims and negatively lower orthant dependent inter-arrival times. In particular, when the claims are consistently varying-tailed, an asymptotic equivalent formula is presented.
Determination of the arrival time of ICME Shock to Earth's Magnetosphere
Shaltout, Mosalam; Mahrous, Ayman; Shaltout, Mosalam; Youssef, Mohamed; Ramy Mawad, Rr.
. We are estimated the arrival time of ICME shock to the Earth's magnetosphere during the solar cycle 23rd , for the period 1996-2005, by using certain temporal and spatial conditions. We selected the Data of the SSC events from Preliminary Reports of the ISGI (Institut de Physique du Globe, France). While the associated CMES during the same period are selected from SOHO/LASCO/C2. We construct a numerical model to estimate the arrival time of the CME reached the Earth's magnetosphere. According to our model, we found high correlation between CMEs and their shocks (R = 75%). In addition , we studied the characteristics of the CMEs which reached to Earth's magnetosphere. Also we examined the relation between the logarithms of the halo CME energy and the duration of the associated intense geomagnetic storms(Dst < -100nT ). We found a significant correlation (R = 0.82) between the length of the duration of the intense geomagnetic storms and the related halo CME energies. This means that the halo CMEs events is the main source of the energy transfer processes into the Earth's magnetosphere.
The NANOGrav Nine-Year Data Set: Noise Budget for Pulsar Arrival Times on Intraday Timescales
Lam, M T; Chatterjee, S; Arzoumanian, Z; Crowter, K; Demorest, P B; Dolch, T; Ellis, J A; Ferdman, R D; Fonseca, E F; Gonzalez, M E; Jones, G; Jones, M L; Levin, L; Madison, D R; McLaughlin, M A; Nice, D J; Pennucci, T T; Ransom, S M; Siemens, X; Stairs, I H; Stovall, K; Swiggum, J K; Zhu, W W
2015-01-01
The use of pulsars as astrophysical clocks for gravitational wave experiments demands the highest possible timing precision. Pulse times of arrival (TOAs) are limited by stochastic processes that occur in the pulsar itself, along the line of sight through the interstellar medium, and in the measurement process. On timescales of seconds to hours, the TOA variance exceeds that from template-fitting errors due to additive noise. We assess contributions to the total variance from two additional effects: amplitude and phase jitter intrinsic to single pulses and changes in the interstellar impulse response from scattering. The three effects have different dependencies on time, frequency, and pulse signal-to-noise ratio. We use data on 37 pulsars from the North American Nanohertz Observatory for Gravitational Waves to assess the individual contributions to the overall intraday noise budget for each pulsar. We detect jitter in 22 pulsars and estimate the average value of RMS jitter in our pulsars to be $\\sim 1\\%$ of ...
Kerr, Matthew; Johnston, Simon; Shannon, Ryan
2015-01-01
In a search for periodic variation in the arrival times of pulses from 151 young, energetic pulsars, we have identified seven cases of modulation consistent with one or two harmonics of a single fundamental with time-scale 0.5-1.5 yr. We use simulations to show that these modulations are statistically significant and of high quality (sinusoidal) even when contaminated by the strong stochastic timing noise common to young pulsars. Although planetary companions could induce such modulation, the large implied masses and 2:1 mean motion resonances challenge such an explanation. Instead, the modulation is likely to be intrinsic to the pulsar, arising from quasi-periodic switching between stable magnetospheric states, and we propose that precession of the neutron star may regulate this switching.
Institute of Scientific and Technical Information of China (English)
He Wen; Ma Zhenyu; Wang Xingli
2005-01-01
The effect of vibratory stress relief (VSR) is usually evaluated with the indirect method of observing the change of amplitude frequency response characteristics of structures. A new kind of evaluating method of VSR based on the ultrasonic time-of-arrival method (UTM), which can obtain the residual stress directly through measuring the propagation time of ultrasonic wave in the material, is presented. At first, the principle of the measuring method of residual stress based on UTM is analyzed. Then the measuring system of the method is described, which is in virtue of ultrasonic flaw detector and high-sampling-rate digital oscillograph. And a set of calibration system that contains a piece of standard specimen is also introduced. Experimental results prove the relation between the residual stress and the propagation time of ultrasonic in workpieces. Finally, the measuring and calibration systems are applied in evaluating the effect of VSR. The final test results show that the method is effective.
Energy Technology Data Exchange (ETDEWEB)
Thompson, C.B.; McArthur, R.D. [Univ. and Community College System of Nevada, Las Vegas, NV (United States); Hutchinson, S.W. [Mead Johnson Nutritional Group, Evansville, IN (United States)
1994-09-01
As part of the U.S. Department of Energy`s Off-Site Radiation Exposure Review Project, the time of fallout arrival and the H+12 exposure rate were estimated for populated locations in Arizona, California, Nevada, and Utah that were affected by fallout from one or more nuclear tests at the Nevada Test Site. Estimates of exposure rate were derived from measured values recorded before and after each test by fallout monitors in the field. The estimate for a given location was obtained by retrieving from a data base all measurements made in the vicinity, decay-correcting them to H+12, and calculating an average. Estimates were also derived from maps produced after most events that show isopleths of exposure rate and time of fallout arrival. Both sets of isopleths on these maps were digitized, and kriging was used to interpolate values at the nodes of a 10-km grid covering the pattern. The values at any location within the grid were then estimated from the values at the surrounding grid nodes. Estimates of dispersion (standard deviation) were also calculated. The Town Data Base contains the estimates for all combinations of location and nuclear event for which the estimated mean H+12 exposure rate was greater than three times background. A listing of the data base is included as an appendix. The information was used by other project task groups to estimate the radiation dose that off-site populations and individuals may have received as a result of exposure to fallout from Nevada nuclear tests.
Kendall, William L.; Hines, James E.; Nichols, James D.; Grant, Evan H. Campbell
2013-01-01
Occupancy statistical models that account for imperfect detection have proved very useful in several areas of ecology, including species distribution and spatial dynamics, disease ecology, and ecological responses to climate change. These models are based on the collection of multiple samples at each of a number of sites within a given season, during which it is assumed the species is either absent or present and available for detection while each sample is taken. However, for some species, individuals are only present or available for detection seasonally. We present a statistical model that relaxes the closure assumption within a season by permitting staggered entry and exit times for the species of interest at each site. Based on simulation, our open model eliminates bias in occupancy estimators and in some cases increases precision. The power to detect the violation of closure is high if detection probability is reasonably high. In addition to providing more robust estimation of occupancy, this model permits comparison of phenology across sites, species, or years, by modeling variation in arrival or departure probabilities. In a comparison of four species of amphibians in Maryland we found that two toad species arrived at breeding sites later in the season than a salamander and frog species, and departed from sites earlier.
High Bandwidth Pickup Design for Bunch Arrival-time Monitors for Free-Electron Laser
Angelovski, Aleksandar; Hansli, Matthias; Penirschke, Andreas; Schnepp, Sascha M; Bousonville, Michael; Schlarb, Holger; Bock, Marie Kristin; Weiland, Thomas; Jakoby, Rolf
2012-01-01
In this paper, we present the design and realization of high bandwidth pickup electrodes with a cutoff frequency above 40 GHz. The proposed cone-shaped pickups are part of a bunch arrival-time monitor (BAM) designed for high (> 500 pC) and low (20 pC) bunch charge operation mode providing for a time resolution of less than 10 fs for both operation modes. The proposed design has a fast voltage response, low ringing, and a resonance-free spectrum. For assessing the influence of manufacturing tolerances on the performance of the pickups, an extensive tolerance study has been performed via numerical simulations. A non-hermetic model of the pickups was built for measurement and validation purposes. The measurement and simulation results are in good agreement and demonstrate the capability of the proposed pickup system to meet the given specifications.
High bandwidth pickup design for bunch arrival-time monitors for free-electron laser
Directory of Open Access Journals (Sweden)
Aleksandar Angelovski
2012-11-01
Full Text Available In this paper, we present the design and realization of high bandwidth pickup electrodes with a cutoff frequency above 40 GHz. The proposed cone-shaped pickups are part of a bunch arrival-time monitor designed for high (>500 pC and low (20 pC bunch charge operation mode providing for a time resolution of less than 10 fs for both operation modes. The proposed design has a fast voltage response, low ringing, and a resonance-free spectrum. For assessing the influence of manufacturing tolerances on the performance of the pickups, an extensive tolerance study has been performed via numerical simulations. A nonhermetic model of the pickups was built for measurement and validation purposes. The measurement and simulation results are in good agreement and demonstrate the capability of the proposed pickup system to meet the given specifications.
Seismicity and arrival-time residuals from the Victoria Earthquake of June 9, 1980
Energy Technology Data Exchange (ETDEWEB)
Wong, V.; Frez, J.
1981-01-01
Hypocenter distribution in space and time of the aftershock activity from the Victoria Earthquake of June 9, 1980 was studied. It was concluded that the main event excited aftershocks in several pre-existing nests at the northwest end of the Cerro Prieto Fault, but no significant activity occurred at the immediate neighborhood of the main event. The depth of the aftershocks increases with the distance from the northwest end of the fault and this feature might be related with the higher temperatures and the spreading center located between the ends of the Imperial and Cerro Prieto Faults. The significance of the arrival-times residuals for local and regional stations is discussed both for P and S-waves and the importance of obtaining station corrections is emphasized. The non-uniqueness in determining a structure which minimizes the residuals is illustrated. Two different structures which satisfy the local data are presented.
Real Time Metrics and Analysis of Integrated Arrival, Departure, and Surface Operations
Sharma, Shivanjli; Fergus, John
2017-01-01
A real time dashboard was developed in order to inform and present users notifications and integrated information regarding airport surface operations. The dashboard is a supplement to capabilities and tools that incorporate arrival, departure, and surface air-traffic operations concepts in a NextGen environment. As trajectory-based departure scheduling and collaborative decision making tools are introduced in order to reduce delays and uncertainties in taxi and climb operations across the National Airspace System, users across a number of roles benefit from a real time system that enables common situational awareness. In addition to shared situational awareness the dashboard offers the ability to compute real time metrics and analysis to inform users about capacity, predictability, and efficiency of the system as a whole. This paper describes the architecture of the real time dashboard as well as an initial set of metrics computed on operational data. The potential impact of the real time dashboard is studied at the site identified for initial deployment and demonstration in 2017; Charlotte-Douglas International Airport. Analysis and metrics computed in real time illustrate the opportunity to provide common situational awareness and inform users of metrics across delay, throughput, taxi time, and airport capacity. In addition, common awareness of delays and the impact of takeoff and departure restrictions stemming from traffic flow management initiatives are explored. The potential of the real time tool to inform the predictability and efficiency of using a trajectory-based departure scheduling system is also discussed.
Becker, Peter H; Dittmann, Tobias; Ludwigs, Jan-Dieter; Limmer, Bente; Ludwig, Sonja C; Bauch, Christina; Braasch, Alexander; Wendeln, Helmut
2008-08-26
In long-lived vertebrates, individuals generally visit potential breeding areas or populations during one or more seasons before reproducing for the first time. During these years of prospecting, they select a future breeding site, colony, or mate and improve various skills and their physical condition to meet the requirements of reproduction. One precondition of successful reproduction is arrival in time on the breeding grounds. Here, we study the intricate links among the date of initial spring arrival, body mass, sex, and the age of first breeding in the common tern Sterna hirundo, a long-lived migratory colonial seabird. The study is based on a unique, individual-based, long-term dataset of sexed birds, marked with transponders, which allow recording their individual arrival, overall attendance, and clutch initiation remotely and automatically year by year over the entire lifetime at the natal colony site. We show that the seasonal date of initial arrival at the breeding grounds predicts the individual age at first reproduction, which mostly occurs years later. Late first-time arrivals remain delayed birds throughout subsequent years. Our findings reveal that timing of arrival at the site of reproduction and timing of reproduction itself are coherent parameters of individual quality, which are linked with the prospects of the breeding career and may have consequences for fitness.
Pickup design for high bandwidth bunch arrival-time monitors in free-electron lasers
Energy Technology Data Exchange (ETDEWEB)
Angelovski, Aleksandar; Penirschke, Andreas; Jakoby, Rolf [TU Darmstadt (Germany). Institut fuer Mikrowellentechnik und Photonik; Kuhl, Alexander; Schnepp, Sascha [TU Darmstadt (Germany). Graduate School of Computational Engineering; Bock, Marie Kristin; Bousonville, Michael; Schlarb, Holger [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Weiland, Thomas [TU Darmstadt (Germany). Institut fuer Theorie Elektromagnetischer Felder
2012-07-01
The increased demands for low bunch charge operation mode in the free-electron lasers (FELs) require an upgrade of the existing synchronization equipment. As a part of the laser-based synchronization system, the bunch arrival-time monitors (BAMs) should have a sub-10 femtosecond precision for high and low bunch charge operation. In order to fulfill the resolution demands for both modes of operation, the bandwidth of such a BAM should be increased up to a cutoff frequency of 40 GHz. In this talk, we present the design and the realization of high bandwidth cone-shaped pickup electrodes as a part of the BAM for the FEL in Hamburg (FLASH) and the European X-ray free-electron laser (European XFEL). The proposed pickup was simulated with CST STUDIO SUITE, and a non-hermetic model was built up for radio frequency (rf) measurements.
Cuff-less blood pressure measurement using pulse arrival time and a Kalman filter
Zhang, Qiang; Chen, Xianxiang; Fang, Zhen; Xue, Yongjiao; Zhan, Qingyuan; Yang, Ting; Xia, Shanhong
2017-02-01
The present study designs an algorithm to increase the accuracy of continuous blood pressure (BP) estimation. Pulse arrival time (PAT) has been widely used for continuous BP estimation. However, because of motion artifact and physiological activities, PAT-based methods are often troubled with low BP estimation accuracy. This paper used a signal quality modified Kalman filter to track blood pressure changes. A Kalman filter guarantees that BP estimation value is optimal in the sense of minimizing the mean square error. We propose a joint signal quality indice to adjust the measurement noise covariance, pushing the Kalman filter to weigh more heavily on measurements from cleaner data. Twenty 2 h physiological data segments selected from the MIMIC II database were used to evaluate the performance. Compared with straightforward use of the PAT-based linear regression model, the proposed model achieved higher measurement accuracy. Due to low computation complexity, the proposed algorithm can be easily transplanted into wearable sensor devices.
Directory of Open Access Journals (Sweden)
Fawad Zaman
2012-07-01
Full Text Available In this study, we propose a method based on Particle Swarm Optimization for estimating Direction of Arrival of sources impinging on uniform linear array in the presence of noise. Mean Square Error is used as a fitness function which is optimum in nature and avoids any ambiguity among the angles that are supplement to each others. Multiple sources have been taken in the far field of the sensors array. In Case-I the sources are assumed to be far away from each other whereas, in case-II they are assumed to be close enough to each other. The reliability and effectiveness of this proposed algorithm is tested on the bases of comprehensive statistical analysis. The proposed algorithm require single snapshot and can be applied in real time situation.
Time-limited polling systems with batch arrivals and phase-type service times
Al Hanbali, A.M.; Haan, de R.; Boucherie, R.J.; Ommeren, van J.K.
2012-01-01
In this paper, we develop a general framework to analyze polling systems with either the autonomous-server or the time-limited service discipline. According to the autonomous-server discipline, the server continues servicing a queue for a certain period of time. According to the time-limited service
41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?
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...
A Bayesian parameter estimation approach to pulsar time-of-arrival analysis
Messenger, C; Demorest, P; Ransom, S
2011-01-01
The increasing sensitivities of pulsar timing arrays to ultra-low frequency (nHz) gravitational waves promises to achieve direct gravitational wave detection within the next 5-10 years. While there are many parallel efforts being made in the improvement of telescope sensitivity, the detection of stable millisecond pulsars and the improvement of the timing software, there are reasons to believe that the methods used to accurately determine the time-of-arrival (TOA) of pulses from radio pulsars can be improved upon. More specifically, the determination of the uncertainties on these TOAs, which strongly affect the ability to detect GWs through pulsar timing, may be unreliable. We propose two Bayesian methods for the generation of pulsar TOAs starting from pulsar "search-mode" data and pre-folded data. These methods are applied to simulated toy-model examples and in this initial work we focus on the issue of uncertainties in the folding period. The final results of our analysis are expressed in the form of poster...
Rapid estimation of earthquake magnitude from the arrival time of the peak high‐frequency amplitude
Noda, Shunta; Yamamoto, Shunroku; Ellsworth, William L.
2016-01-01
We propose a simple approach to measure earthquake magnitude M using the time difference (Top) between the body‐wave onset and the arrival time of the peak high‐frequency amplitude in an accelerogram. Measured in this manner, we find that Mw is proportional to 2logTop for earthquakes 5≤Mw≤7, which is the theoretical proportionality if Top is proportional to source dimension and stress drop is scale invariant. Using high‐frequency (>2 Hz) data, the root mean square (rms) residual between Mw and MTop(M estimated from Top) is approximately 0.5 magnitude units. The rms residuals of the high‐frequency data in passbands between 2 and 16 Hz are uniformly smaller than those obtained from the lower‐frequency data. Top depends weakly on epicentral distance, and this dependence can be ignored for distances earthquake produces a final magnitude estimate of M 9.0 at 120 s after the origin time. We conclude that Top of high‐frequency (>2 Hz) accelerograms has value in the context of earthquake early warning for extremely large events.
Energy Technology Data Exchange (ETDEWEB)
Kramme, Johanna [Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen (Germany); Univ. Bremen (Germany). Faculty of Physics and Electronics; Gregori, Johannes [mediri GmbH, Heidelberg (Germany); Diehl, Volker [Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen (Germany); ZEMODI (Zentrum fuer morderne Diagnostik), Bremen (Germany); Madai, Vince I.; Sobesky, Jan [Charite-Universitaetsmedizin Berlin (Germany). Center for Stroke Research Berlin (CSB); Charite-Universitaetsmedizin Berlin (Germany). Dept. of Neurology; Samson-Himmelstjerna, Frederico C. von [Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen (Germany); Charite-Universitaetsmedizin Berlin (Germany). Center for Stroke Research Berlin (CSB); Charite-Universitaetsmedizin Berlin (Germany). Dept. of Neurology; Lentschig, Markus [ZEMODI (Zentrum fuer morderne Diagnostik), Bremen (Germany); Guenther, Matthias [Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen (Germany); Univ. Bremen (Germany). Faculty of Physics and Electronics; mediri GmbH, Heidelberg (Germany)
2015-07-01
The improvement in Arterial Spin Labeling (ASL) perfusion quantification, especially for delayed bolus arrival times (BAT), with an acquisition redistribution scheme mitigating the T1 decay of the label in multi-TI ASL measurements is investigated. A multi inflow time (TI) 3D-GRASE sequence is presented which adapts the distribution of acquisitions accordingly, by keeping the scan time constant. The MR sequence increases the number of averages at long TIs and decreases their number at short TIs and thus compensating the T1 decay of the label. The improvement of perfusion quantification is evaluated in simulations as well as in-vivo in healthy volunteers and patients with prolonged BATs due to age or steno-occlusive disease. The improvement in perfusion quantification depends on BAT. At healthy BATs the differences are small, but become larger for longer BATs typically found in certain diseases. The relative error of perfusion is improved up to 30% at BATs > 1500 ms in comparison to the standard acquisition scheme. This adapted acquisition scheme improves the perfusion measurement in comparison to standard multi-TI ASL implementations. It provides relevant benefit in clinical conditions that cause prolonged BATs and is therefore of high clinical relevance for neuroimaging of steno-occlusive diseases.
Wavepacket approach to particle diffraction by thin targets: Quantum trajectories and arrival times
Efthymiopoulos, C; Contopoulos, G
2011-01-01
We develop a wavepacket approach to the diffraction of charged particles by a thin material target and we use the de Broglie-Bohm quantum trajectories to study various phenomena in this context. We find the form of the separator, i.e.the limit between the domains of prevalence of the ingoing and outgoing quantum flow. The structure of the quantum-mechanical currents in the neighborhood of the separator implies the formation of an array of \\emph{quantum vortices} (nodal point - X point complexes). We show how the deformation of the separatior near Bragg angles explains the emergence of a diffraction pattern by the de Broglie - Bohm trajectories. We calculate the arrival time distributions for particles scattered at different angles. The predictions of the de Broglie - Bohm theory for $\\Delta T$ turn to be different from estimates of the same quantity using other theories on time observables like the sum-over-histories or the Kijowski approach. We propose an experimental setup aiming to test such predictions. F...
Energy Technology Data Exchange (ETDEWEB)
Vasco, D.W.; Ferretti, Alessandro; Novali, Fabrizio
2008-05-01
Transient pressure variations within a reservoir can be treated as a propagating front and analyzed using an asymptotic formulation. From this perspective one can define a pressure 'arrival time' and formulate solutions along trajectories, in the manner of ray theory. We combine this methodology and a technique for mapping overburden deformation into reservoir volume change as a means to estimate reservoir flow properties, such as permeability. Given the entire 'travel time' or phase field, obtained from the deformation data, we can construct the trajectories directly, there-by linearizing the inverse problem. A numerical study indicates that, using this approach, we can infer large-scale variations in flow properties. In an application to Interferometric Synthetic Aperture (InSAR) observations associated with a CO{sub 2} injection at the Krechba field, Algeria, we image pressure propagation to the northwest. An inversion for flow properties indicates a linear trend of high permeability. The high permeability correlates with a northwest trending fault on the flank of the anticline which defines the field.
1991-03-01
FORTRAN for the VAX computer with the only supported output device being the Imagen laserprinter con- nected to the VAX machine. The new processing...interference effects described earlier. It is unfortunate that the A and C arrivals were not more stable, as a direct visual comparison might yield...outputs provide visual indications of the process and statistical processing of these outputs yields much additional information. For instance, the arrival
Directory of Open Access Journals (Sweden)
Richard Leigh
Full Text Available PURPOSE: To determine if applying an arrival time correction (ATC to dynamic susceptibility contrast (DSC based permeability imaging will improve its ability to identify contrast leakage in stroke patients for whom the shape of the measured curve may be very different due to hypoperfusion. MATERIALS AND METHODS: A technique described in brain tumor patients was adapted to incorporate a correction for delayed contrast delivery due to perfusion deficits. This technique was applied to the MRIs of 9 stroke patients known to have blood-brain barrier (BBB disruption on T1 post contrast imaging. Regions of BBB damage were compared with normal tissue from the contralateral hemisphere. Receiver operating characteristic (ROC analysis was performed to compare the detection of BBB damage before and after ATC. RESULTS: ATC improved the area under the curve (AUC of the ROC from 0.53 to 0.70. The sensitivity improved from 0.51 to 0.67 and the specificity improved from 0.57 to 0.66. Visual inspection of the ROC curve revealed that the performance of the uncorrected analysis was worse than random guess at some thresholds. CONCLUSIONS: The ability of DSC permeability imaging to identify contrast enhancing tissue in stroke patients improved considerably when an ATC was applied. Using DSC permeability imaging in stroke patients without an ATC may lead to false identification of BBB disruption.
Fossil and genomic evidence constrains the timing of bison arrival in North America
Froese, Duane; Stiller, Mathias; Heintzman, Peter D.; Reyes, Alberto V.; Zazula, Grant D.; Soares, André E. R.; Meyer, Matthias; Hall, Elizabeth; Jensen, Britta J. L.; Arnold, Lee J.; MacPhee, Ross D. E.; Shapiro, Beth
2017-03-01
The arrival of bison in North America marks one of the most successful large-mammal dispersals from Asia within the last million years, yet the timing and nature of this event remain poorly determined. Here, we used a combined paleontological and paleogenomic approach to provide a robust timeline for the entry and subsequent evolution of bison within North America. We characterized two fossil-rich localities in Canada’s Yukon and identified the oldest well-constrained bison fossil in North America, a 130,000-y-old steppe bison, Bison cf. priscus. We extracted and sequenced mitochondrial genomes from both this bison and from the remains of a recently discovered, ˜120,000-y-old giant long-horned bison, Bison latifrons, from Snowmass, Colorado. We analyzed these and 44 other bison mitogenomes with ages that span the Late Pleistocene, and identified two waves of bison dispersal into North America from Asia, the earliest of which occurred ˜195-135 thousand y ago and preceded the morphological diversification of North American bison, and the second of which occurred during the Late Pleistocene, ˜45-21 thousand y ago. This chronological arc establishes that bison first entered North America during the sea level lowstand accompanying marine isotope stage 6, rejecting earlier records of bison in North America. After their invasion, bison rapidly colonized North America during the last interglaciation, spreading from Alaska through continental North America; they have been continuously resident since then.
Energy Technology Data Exchange (ETDEWEB)
Choi, Young Chul; Park, Tae Jin [KAERI, Daejeon (Korea, Republic of)
2016-05-15
Source localization in a dispersive medium has been carried out based on the time-of-arrival-differences (TOADs) method: a triangulation method and a circle intersection technique. Recent signal processing advances have led to calculation TOAD using a joint time-frequency analysis of the signal, where a short-time Fourier transform(STFT) and wavelet transform can be included as popular algorithms. The time-frequency analysis method is able to provide various information and more reliable results such as seismic-attenuation estimation, dispersive characteristics, a wave mode analysis, and temporal energy distribution of signals compared with previous methods. These algorithms, however, have their own limitations for signal processing. In this paper, the effective use of proposed algorithm in detecting crack wave arrival time and source localization in rock masses suggest that the evaluation and real-time monitoring on the intensity of damages related to the tunnels or other underground facilities is possible. Calculation of variances resulted from moving windows as a function of their size differentiates the signature from noise and from crack signal, which lead us to determine the crack wave arrival time. Then, the source localization is determined to be where the variance of crack wave velocities from real and virtual crack localization becomes a minimum. To validate our algorithm, we have performed experiments at the tunnel, which resulted in successful determination of the wave arrival time and crack localization.
Tsai, Christina; Hung, Serena
2016-04-01
To more precisely describe particle movement in surface water, both the random particle arrival process at the receiving water and the stochastic particle movement in the receiving water should be carefully considered in sediment transport modeling. In this study, a stochastic framework is developed for a probabilistic description of discrete particle transport through a probability density function of sediment concentrations and transport rates. In order to more realistically describe the particle arrivals into receiving waters at random times and with a probabilistic particle number in each arrival, the continuous-time batch Markovian arrival process is introduced. The particle tracking model (PTM) composed of physically based stochastic differential equations (SDEs) for particle trajectory is then used to depict the random movement of particles in the receiving water. Particle deposition and entrainment processes are considered in the model. It is expected that the particle concentrations in the receiving water and particle transport rates can be mathematically expressed as a stochastic process. Compared with deterministic modeling, the proposed approach has the advantage of capturing any randomly selected scenarios (or realizations) of flow and sediment properties. Availability of a more sophisticated stochastic process for random particle arrival processes can assist in quantifying the probabilistic characteristics of sediment transport rates and concentrations. In addition, for a given turbidity threshold, the risk of exceeding a pre-established water quality standard can be quantified as needed.
Directory of Open Access Journals (Sweden)
M. Owens
2004-01-01
Full Text Available Three existing models of Interplanetary Coronal Mass Ejection (ICME transit between the Sun and the Earth are compared to coronagraph and in situ observations: all three models are found to perform with a similar level of accuracy (i.e. an average error between observed and predicted 1AU transit times of approximately 11h. To improve long-term space weather prediction, factors influencing CME transit are investigated. Both the removal of the plane of sky projection (as suffered by coronagraph derived speeds of Earth directed CMEs and the use of observed values of solar wind speed, fail to significantly improve transit time prediction. However, a correlation is found to exist between the late/early arrival of an ICME and the width of the preceding sheath region, suggesting that the error is a geometrical effect that can only be removed by a more accurate determination of a CME trajectory and expansion. The correlation between magnetic field intensity and speed of ejecta at 1AU is also investigated. It is found to be weak in the body of the ICME, but strong in the sheath, if the upstream solar wind conditions are taken into account.
Key words. Solar physics, astronomy and astrophysics (flares and mass ejections – Interplanetary physics (interplanetary magnetic fields; sources of the solar wind
Arzoumanian, Z; Burke-Spolaor, S; Chamberlin, S; Chatterjee, S; Christy, B; Cordes, J M; Cornish, N; Crowter, K; Demorest, P B; Dolch, T; Ellis, J A; Ferdman, R D; Fonseca, E; Garver-Daniels, N; Gonzalez, M E; Jenet, F A; Jones, G; Jones, M; Kaspi, V M; Koop, M; Lazio, T J W; Lam, M T; Levin, L; Lommen, A N; Lorimer, D R; Luo, J; Lynch, R S; Madison, D; McLaughlin, M A; McWilliams, S T; Nice, D J; Palliyaguru, N; Pennucci, T T; Ransom, S M; Siemens, X; Stairs, I H; Stinebring, D R; Stovall, K; Swiggum, J K; Vallisneri, M; van Haasteren, R; Wang, Y; Zhu, W
2015-01-01
We present high-precision timing observations spanning up to nine years for 37 millisecond pulsars monitored with the Green Bank and Arecibo radio telescopes as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project. We describe the observational and instrumental setups used to collect the data, and methodology applied for calculating pulse times of arrival; these include novel methods for measuring instrumental offsets and characterizing low signal-to-noise ratio timing results. The time of arrival data are fit to a physical timing model for each source, including terms that characterize time-variable dispersion measure and frequency-dependent pulse shape evolution. In conjunction with the timing model fit, we have performed a Bayesian analysis of a parameterized timing noise model for each source, and detect evidence for time-correlated "red" signals in 10 of the pulsars. Subsequent papers in this series will present further analysis of this data set aimed at detecting o...
Design and Performance Evaluation on Ultra-Wideband Time-Of-Arrival 3D Tracking System
Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Dusl, John
2012-01-01
A three-dimensional (3D) Ultra-Wideband (UWB) Time--of-Arrival (TOA) tracking system has been studied at NASA Johnson Space Center (JSC) to provide the tracking capability inside the International Space Station (ISS) modules for various applications. One of applications is to locate and report the location where crew experienced possible high level of carbon-dioxide and felt upset. In order to accurately locate those places in a multipath intensive environment like ISS modules, it requires a robust real-time location system (RTLS) which can provide the required accuracy and update rate. A 3D UWB TOA tracking system with two-way ranging has been proposed and studied. The designed system will be tested in the Wireless Habitat Testbed which simulates the ISS module environment. In this presentation, we discuss the 3D TOA tracking algorithm and the performance evaluation based on different tracking baseline configurations. The simulation results show that two configurations of the tracking baseline are feasible. With 100 picoseconds standard deviation (STD) of TOA estimates, the average tracking error 0.2392 feet (about 7 centimeters) can be achieved for configuration Twisted Rectangle while the average tracking error 0.9183 feet (about 28 centimeters) can be achieved for configuration Slightly-Twisted Top Rectangle . The tracking accuracy can be further improved with the improvement of the STD of TOA estimates. With 10 picoseconds STD of TOA estimates, the average tracking error 0.0239 feet (less than 1 centimeter) can be achieved for configuration "Twisted Rectangle".
Time of Arrival Estimation in Probability-Controlled Generalized CDMA Systems
Directory of Open Access Journals (Sweden)
Hagit Messer
2007-11-01
Full Text Available In recent years, more and more wireless communications systems are required to provide also a positioning measurement. In code division multiple access (CDMA communication systems, the positioning accuracy is significantly degraded by the multiple access interference (MAI caused by other users in the system. This MAI is commonly managed by a power control mechanism, and yet, MAI has a major effect on positioning accuracy. Probability control is a recently introduced interference management mechanism. In this mechanism, a user with excess power chooses not to transmit some of its symbols. The information in the nontransmitted symbols is recovered by an error-correcting code (ECC, while all other users receive a more reliable data during these quiet periods. Previous research had shown that the implementation of a probability control mechanism can significantly reduce the MAI. In this paper, we show that probability control also improves the positioning accuracy. We focus on time-of-arrival (TOA based positioning systems. We analyze the TOA estimation performance in a generalized CDMA system, in which the probability control mechanism is employed, where the transmitted signal is noncontinuous with a symbol transmission probability smaller than 1. The accuracy of the TOA estimation is determined using appropriate modifications of the Cramer-Rao bound on the delay estimation. Keeping the average transmission power constant, we show that the TOA accuracy of each user does not depend on its transmission probability, while being a nondecreasing function of the transmission probability of any other user. Therefore, a generalized, noncontinuous CDMA system with a probability control mechanism can always achieve better positioning performance, for all users in the network, than a conventional, continuous, CDMA system.
Lee, Moon Ho; Dudin, Alexander; Shaban, Alexy; Pokhrel, Subash Shree; Ma, Wen Ping
Formulae required for accurate approximate calculation of transition probabilities of embedded Markov chain for single-server queues of the GI/M/1, GI/M/1/K, M/G/1, M/G/1/K type with heavy-tail lognormal distribution of inter-arrival or service time are given.
Institute of Scientific and Technical Information of China (English)
Taikun Shi; Jianzhong Zhang; Zhonglai Huang; Changkun Jin
2015-01-01
In order to improve the efficiency of 3D near-surface velocity model building, we develop a layer-stripping method using seismic first-arrival times. The velocity model within a Common Mid-Point (CMP) gather is assumed to be stratified into thin layers, and the velocity of each layer var-ies linearly with depth. The thickness and velocity of the top layer are estimated using minimum-offset first-arrival data in a CMP gather. Then the top layer is stripped and the second layer becomes a new top layer. After removing the effect of the top layer from the former first-arrival data, the new first-arrival data are obtained and then used to estimate the parameters of the second layer. In this manner, the velocity model, being regarded as that at a CMP location, is built layer-by-layer from the top to the bottom. A 3D near-surface velocity model is then formed using the velocity models at all CMP locations. The tests on synthetic and observed seismic data show that the layer-stripping method can be used to build good near-surface velocity models for static correction, and its computation speed is ap-proximately hundred times faster than that of grid tomography.
MIN Htwe, Y. M.
2016-12-01
Myanmar has suffered many times from earthquake disasters and four times from tsunamis according to historical data. The purpose of this study is to estimate the tsunami arrival time and maximum tsunami wave amplitude for the Rakhine coast of Myanmar using the TUNAMI F1 model. In this study I calculate the tsunami arrival time and maximum tsunami wave amplitude based on a tsunamigenic earthquake source of moment magnitude 8.5 in the Arakan subduction zone off the west-coast of Myanmar, using the TUNAMI F1 model, selecting eight points on Rakhine coast. The model result indicates that the tsunami waves would first hit Kyaukpyu on the Rakhine coast about 0.05 minutes after the onset of a magnitude 8.5 earthquake, and the maximum tsunami wave amplitude would be 2.37 meters.
Martin, Stephanie L.-O.; Carek, Andrew M.; Kim, Chang-Sei; Ashouri, Hazar; Inan, Omer T.; Hahn, Jin-Oh; Mukkamala, Ramakrishna
2016-12-01
Pulse transit time (PTT) is being widely pursued for cuff-less blood pressure (BP) monitoring. Most efforts have employed the time delay between ECG and finger photoplethysmography (PPG) waveforms as a convenient surrogate of PTT. However, these conventional pulse arrival time (PAT) measurements include the pre-ejection period (PEP) and the time delay through small, muscular arteries and may thus be an unreliable marker of BP. We assessed a bathroom weighing scale-like system for convenient measurement of ballistocardiography and foot PPG waveforms – and thus PTT through larger, more elastic arteries – in terms of its ability to improve tracking of BP in individual subjects. We measured “scale PTT”, conventional PAT, and cuff BP in humans during interventions that increased BP but changed PEP and smooth muscle contraction differently. Scale PTT tracked the diastolic BP changes well, with correlation coefficient of ‑0.80 ± 0.02 (mean ± SE) and root-mean-squared-error of 7.6 ± 0.5 mmHg after a best-case calibration. Conventional PAT was significantly inferior in tracking these changes, with correlation coefficient of ‑0.60 ± 0.04 and root-mean-squared-error of 14.6 ± 1.5 mmHg (p < 0.05). Scale PTT also tracked the systolic BP changes better than conventional PAT but not to an acceptable level. With further development, scale PTT may permit reliable, convenient measurement of BP.
Batch arrival retrial queue with delay time and additional multi-optional repair
Directory of Open Access Journals (Sweden)
D. Sumitha
2016-12-01
Full Text Available This paper deals with MX/G/1 retrial queue with unreliable server and multi-optional repair. It is assumed that the server is subject to active breakdowns and the repair of the failed server starts after a random amount of time. Restoration of the failed server is done with two phases, first essential and second multi optional. After completion of the repair the server continues the interrupted service and it is not allowed to accept new customers until the interrupted customer leaves the system. The retrial, service, delay and repair times are arbitrarily distributed. The model is analysed using the supplementary variable technique and the probability generating function of system size at random epoch and stochastic decomposition are obtained. Performance measures and reliability indices to predict the behaviour of the system are derived.
DEFF Research Database (Denmark)
Clausen, Jens; Heinesen, Eskil; Hummelgaard, Hans
2009-01-01
We analyse the effect of active labour-market programmes on the hazard rate into regular employment for newly arrived immigrants using the timing-of-events duration model. We take account of language course participation and progression in destination country language skills. We use rich administ......We analyse the effect of active labour-market programmes on the hazard rate into regular employment for newly arrived immigrants using the timing-of-events duration model. We take account of language course participation and progression in destination country language skills. We use rich...... administrative data from Denmark. We find substantial lock-in effects of participation in active labour-market programmes. Post programme effects on the hazard rate to regular employment are significantly positive for wage subsidy programmes, but not for other types of programmes. For language course...... participants, improvement in language proficiency has significant and substantial positive effects on the hazard rate to employment....
Directory of Open Access Journals (Sweden)
Yogesh Tiwari
2014-01-01
Full Text Available Background: Emergency Department (ED of tertiary health care institute in India is mostly overcrowded, over utilized and inappropriately staffed. The challenges of overcrowded EDs and ill-managed patient flow and admission processes result in excessively long waits for patients. Aim: The objective of the present study was to analyze the patient flow system by assessing the arrival and waiting time distribution of patients in an Emergency out Patient Department (EOPD. Materials and Methods: This short cross-sectional descriptive study was conducted in the EOPD of a Tertiary level health care Institution in North India in the month of May, 2011. The data was obtained from 591 patients, who were present in the EOPD during the month of May, 2011. The waiting time, inter arrival time between two consecutive patients were calculated in addition to the daily census data (discharge rate, admission rate and transfer out rates etc. of the emergency. Results: Arrival time pattern of patients in the EOPD was highly stochastic with the peak arrival hours to be "9.00-12.00 h" in which around 26.3% patients arrived in the EOPD. The primary waiting areas of patients included patients "under observation" (29.6%; "waiting for routine diagnostic tests" (16.4% and "waiting for discharge" (14.6%. Around 71% patients were waiting due to reasons within emergency complex. Conclusion: The patient flow of the ED could only be addressed by multifaceted, multidisciplinary and hospital wide approach.
Li, Xi-Bing; Wang, Ze-Wei; Dong, Long-Jun
2016-01-12
Microseismic monitoring systems using local location techniques tend to be timely, automatic and stable. One basic requirement of these systems is the automatic picking of arrival times. However, arrival times generated by automated techniques always contain large picking errors (LPEs), which may make the location solution unreliable and cause the integrated system to be unstable. To overcome the LPE issue, we propose the virtual field optimization method (VFOM) for locating single-point sources. In contrast to existing approaches, the VFOM optimizes a continuous and virtually established objective function to search the space for the common intersection of the hyperboloids, which is determined by sensor pairs other than the least residual between the model-calculated and measured arrivals. The results of numerical examples and in-site blasts show that the VFOM can obtain more precise and stable solutions than traditional methods when the input data contain LPEs. Furthermore, we discuss the impact of LPEs on objective functions to determine the LPE-tolerant mechanism, velocity sensitivity and stopping criteria of the VFOM. The proposed method is also capable of locating acoustic sources using passive techniques such as passive sonar detection and acoustic emission.
Energy Technology Data Exchange (ETDEWEB)
Arzoumanian, Zaven [Center for Research and Exploration in Space Science and Technology and X-Ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States); Brazier, Adam; Chatterjee, Shami; Cordes, James M.; Dolch, Timothy [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Burke-Spolaor, Sarah; Demorest, Paul B. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Chamberlin, Sydney [Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States); Christy, Brian [Department of Physics and Astronomy, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA 17604 (United States); Cornish, Neil [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Crowter, Kathryn; Fonseca, Emmanuel; Gonzalez, Marjorie E. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Ellis, Justin A. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr. Pasadena CA 91109 (United States); Ferdman, Robert D.; Kaspi, Victoria M. [Department of Physics, McGill University, 3600 rue Universite, Montreal, QC H3A 2T8 (Canada); Garver-Daniels, Nathan; Jones, Megan L. [Department of Physics, West Virginia University, P.O. Box 6315, Morgantown, WV 26505 (United States); Jenet, Fredrick A. [Center for Gravitational Wave Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States); Jones, Glenn, E-mail: pdemores@nrao.edu [Department of Physics, Columbia University, 550 W. 120th St. New York, NY 10027 (United States); Collaboration: NANOGrav Collaboration; and others
2015-11-01
We present high-precision timing observations spanning up to nine years for 37 millisecond pulsars monitored with the Green Bank and Arecibo radio telescopes as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project. We describe the observational and instrumental setups used to collect the data, and methodology applied for calculating pulse times of arrival; these include novel methods for measuring instrumental offsets and characterizing low signal-to-noise ratio timing results. The time of arrival data are fit to a physical timing model for each source, including terms that characterize time-variable dispersion measure and frequency-dependent pulse shape evolution. In conjunction with the timing model fit, we have performed a Bayesian analysis of a parameterized timing noise model for each source, and detect evidence for excess low-frequency, or “red,” timing noise in 10 of the pulsars. For 5 of these cases this is likely due to interstellar medium propagation effects rather than intrisic spin variations. Subsequent papers in this series will present further analysis of this data set aimed at detecting or limiting the presence of nanohertz-frequency gravitational wave signals.
On the objectivity of time derivatives
Directory of Open Access Journals (Sweden)
Matolcsi, Tamas
2008-02-01
Full Text Available A four-dimensional treatment of nonrelativistic space-time gives a natural frame to deal with objective time derivatives. In this framework some well known objective time derivatives of continuum mechanics appear as Lie-derivatives. Their coordinatized forms depends on the tensorial properties of the relevant physical quantities.
Mainz, Roland; Rossi, Giulio Maria; Cirmi, Giovanni; Yang, Yudong; Muecke, Oliver D.; Kärtner, Franz
2017-01-01
We introduce a simple all-inline variation of a balanced optical cross-correlator (BOC) that allows to measure the arrival time difference (ATD), over the full Nyquist bandwidth, with increased common-mode rejection and long-term stability. An FPGA-based signal processing unit allows for real-time signal normalization and enables locking to any setpoint with an unprecedented accuracy of 0.07% within an increased ATD range of more than 400 fs, resulting in attosecond resolution locking. The se...
Connecting speeds, directions and arrival times of 22 coronal mass ejections from the sun to 1 AU
Energy Technology Data Exchange (ETDEWEB)
Möstl, C.; Veronig, A. M.; Rollett, T.; Temmer, M.; Peinhart, V. [Kanzelhöhe Observatory-IGAM, Institute of Physics, University of Graz (Austria); Amla, K.; Hall, J. R.; Liewer, P. C.; De Jong, E. M. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA (United States); Colaninno, R. C. [Space Sciences Division, Naval Research Laboratory, Washington, DC (United States); Davies, J. A.; Harrison, R. A. [RAL Space, Harwell Oxford, Didcot (United Kingdom); Lugaz, N.; Farrugia, C. J.; Galvin, A. B. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH (United States); Liu, Y. D. [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing (China); Luhmann, J. G. [Space Science Laboratory, University of California, Berkeley, CA (United States); Vršnak, B., E-mail: christian.moestl@uni-graz.at [Hvar Observatory, Faculty of Geodesy, University of Zagreb, Kačićeva 26, HR-10000, Zagreb (Croatia)
2014-06-01
Forecasting the in situ properties of coronal mass ejections (CMEs) from remote images is expected to strongly enhance predictions of space weather and is of general interest for studying the interaction of CMEs with planetary environments. We study the feasibility of using a single heliospheric imager (HI) instrument, imaging the solar wind density from the Sun to 1 AU, for connecting remote images to in situ observations of CMEs. We compare the predictions of speed and arrival time for 22 CMEs (in 2008-2012) to the corresponding interplanetary coronal mass ejection (ICME) parameters at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). The list consists of front- and backsided, slow and fast CMEs (up to 2700 km s{sup –1}). We track the CMEs to 34.9 ± 7.1 deg elongation from the Sun with J maps constructed using the SATPLOT tool, resulting in prediction lead times of –26.4 ± 15.3 hr. The geometrical models we use assume different CME front shapes (fixed-Φ, harmonic mean, self-similar expansion) and constant CME speed and direction. We find no significant superiority in the predictive capability of any of the three methods. The absolute difference between predicted and observed ICME arrival times is 8.1 ± 6.3 hr (rms value of 10.9 hr). Speeds are consistent to within 284 ± 288 km s{sup –1}. Empirical corrections to the predictions enhance their performance for the arrival times to 6.1 ± 5.0 hr (rms value of 7.9 hr), and for the speeds to 53 ± 50 km s{sup –1}. These results are important for Solar Orbiter and a space weather mission positioned away from the Sun-Earth line.
DEFF Research Database (Denmark)
Clausen, Jens; Heinesen, Eskil; Hummelgaard, Hans
2009-01-01
We analyse the effect of active labour-market programmes on the hazard rate into regular employment for newly arrived immigrants using the timing-of-events duration model. We take account of language course participation and progression in destination country language skills. We use rich...... administrative data from Denmark. We find substantial lock-in effects of participation in active labour-market programmes. Post programme effects on the hazard rate to regular employment are significantly positive for wage subsidy programmes, but not for other types of programmes. For language course...... participants, improvement in language proficiency has significant and substantial positive effects on the hazard rate to employment....
Repeatable timing of northward departure, arrival and breeding in Black-tailed Godwits
Lourenço, P.M.; Kentie, R.; Schroeder, J.; Groen, N.M.; Hooijmeijer, J.C.E.W.; Piersma, T.
2011-01-01
When early breeding is advantageous, migrants underway to the breeding areas may be time stressed. The timing of sequential events such as migration and breeding is expected to be correlated because of a "domino effect", and would be of particular biological importance if timings are repeatable with
Repeatable timing of northward departure, arrival and breeding in Black-tailed Godwits
Lourenço, P.M.; Kentie, R.; Schroeder, J.; Groen, N.M.; Hooijmeijer, J.C.E.W.; Piersma, T.
2011-01-01
When early breeding is advantageous, migrants underway to the breeding areas may be time stressed. The timing of sequential events such as migration and breeding is expected to be correlated because of a "domino effect", and would be of particular biological importance if timings are repeatable
Energy Technology Data Exchange (ETDEWEB)
Penirschke, Andreas; Angelovski, Aleksandar; Jakoby, Rolf [TU Darmstadt, Institut fuer Mikrowellentechnik und Photonik, Merckstr. 25, 64283 Darmstadt (Germany); Sydlo, Cezary; Bousonville, Michael; Czwalinna, Marie Kristin; Schlarb, Holger [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kuhl, Alexander [University of Hamburg, Physics Department, Accelerator Physics Group (Germany); Weiland, Thomas [Technische Univ. Darmstadt (Germany). Inst. fuer Theorie Elektromagnetischer Felder
2013-07-01
High gain Free-Electron Lasers can generate ultra short X-ray pulses in the femtosecond range. For a stable operation of the FEL, the precise knowledge of the bunch arrival time is crucial. A novel high bandwidth Bunch Arrival time Monitor was recently installed at FLASH to allow a low charge operation mode with a sub-10 fs resolution for bunch charges of 20 pC or more. The BAM is equipped with cone shaped pickups for the precise measurement of both, the high and low bunch charge operation mode. For the extension of FLASH facility to FLASH II new pickups for the high bandwidth BAMs need to be developed. The new BAM needs to maximize the voltage level of the beam induced signal for low charge operation mode in order to provide sufficient signal strength for the subsequent electronics. In this talk, we present concepts to improve the signal strength at the electro-optic modulators for low charge operation at FLASH II and XFEL.
Shi, Tong; Wan, Linfeng; Cheng, Xin; Ding, Mingde; Zhang, Jie
2015-01-01
Accurately predicting the arrival of coronal mass ejections (CMEs) at the Earth based on remote images is of critical significance in the study of space weather. In this paper, we make a statistical study of 21 Earth directed CMEs, exploring in particular the relationship between CME initial speeds and transit times. The initial speed of a CME is obtained by fitting the CME with the Graduated Cylindrical Shell model and is thus free of projection effects. We then use the drag force model to fit results of the transit time versus the initial speed. By adopting different drag regimes, i.e., the viscous, aerodynamics, and hybrid regimes, we get similar results, with the least mean estimation error of the hybrid model of 12.9 hours. CMEs with a propagation angle (the angle between the propagation direction and the Sun-Earth line) larger than its half angular width arrive at the Earth with an angular deviation caused by factors other than the radial solar wind drag. The drag force model cannot be well applied to s...
Yaghoubian, Arezou; De Virgilio, Christian; Destro, Laura; Kaji, Amy H; Putnam, Brant; Neville, Angela L
2010-10-01
In the 80-hour work week era, optimal distribution of the residency workforce is critical. Little data exist as to whether current hours of hospital staffing parallel trends in trauma activity. The purpose of this study was to determine peak periods of trauma volume, severity, need for operative intervention, and mortality and determine if there are differences in mortality based on time period of arrival. We performed a retrospective analysis of the 17,167 patients admitted to our academic Level I trauma center between 2000 and 2007. Each admission was plotted against time of arrival and trends noted. A significant increase in activity occurred between 1700 and 0100 hours. Compared with other shifts, this shift had a disproportionately higher number of patients with penetrating injuries, need for operative intervention, Injury Severity Score (ISS) greater than 15, and death (P hours. In an era of optimizing resident training within the constraints of an 80-hour work week, strong consideration should be made for deploying personnel to match these findings.
IEEE 802.15.4 ZigBee-Based Time-of-Arrival Estimation for Wireless Sensor Networks.
Cheon, Jeonghyeon; Hwang, Hyunsu; Kim, Dongsun; Jung, Yunho
2016-02-05
Precise time-of-arrival (TOA) estimation is one of the most important techniques in RF-based positioning systems that use wireless sensor networks (WSNs). Because the accuracy of TOA estimation is proportional to the RF signal bandwidth, using broad bandwidth is the most fundamental approach for achieving higher accuracy. Hence, ultra-wide-band (UWB) systems with a bandwidth of 500 MHz are commonly used. However, wireless systems with broad bandwidth suffer from the disadvantages of high complexity and high power consumption. Therefore, it is difficult to employ such systems in various WSN applications. In this paper, we present a precise time-of-arrival (TOA) estimation algorithm using an IEEE 802.15.4 ZigBee system with a narrow bandwidth of 2 MHz. In order to overcome the lack of bandwidth, the proposed algorithm estimates the fractional TOA within the sampling interval. Simulation results show that the proposed TOA estimation algorithm provides an accuracy of 0.5 m at a signal-to-noise ratio (SNR) of 8 dB and achieves an SNR gain of 5 dB as compared with the existing algorithm. In addition, experimental results indicate that the proposed algorithm provides accurate TOA estimation in a real indoor environment.
Energy Technology Data Exchange (ETDEWEB)
Matsubara, Susumu; Uchida, Chiharu; Sato, Sei; Ishida, Junichi; Masuya, Ryozo [Hiroshima Teishin Hospital (Japan); Makiguchi, Mako [Radiation Effects Research Foundation, Hiroshima (Japan); Kanamori, Isao [Gifu Coll. of Medical Technology (Japan)
2001-10-01
Hepatic arterial dominant phase in helical dynamic CT was optimized by measuring the arrival time of contrast media (ATCM) with time-density curve (TDC). Subjects were 1005 patients (577 males and 428 females) and 98 nodules diagnosed as advanced hepatocellular carcinoma (HCC). The CT was done with Toshiba 4MHU X-vision SP, ultrasonography with Toshiba SSH-160A and automatic infusion of the contrast medium, iopamidol or iohexol, with Nemotokyorindo Autoenhance A-50. ATCM was found correlated with pulse rate and with arterial diameter, and significantly different between the sex. Elevation slope of TDC was suggested to be made constant by a defined infusion time of the dose corrected by body weight. Fluctuation of TDC among patients , when normalized by ATCM, was found smaller and the TDC was suggested to be useful for better imaging of HCC of less than 10 mm diameter. (K.H.)
Optimizing Time Windows For Managing Export Container Arrivals At Chinese Container Terminals
DEFF Research Database (Denmark)
Chen, Gang; Yang, Zhongzhen
2010-01-01
waiting time, fuel consumption associated with truck idling, storage time of the containerized cargos and yard fee. Secondly, to minimize the total cost, a heuristic is developed based on a genetic algorithm to find a near optimal time window arrangement. The optimized solution involves the position......Management of truck transport in a port area is important for Chinese container ports as heavy traffic congestion not only limits the terminal capacity but also generates serious air pollution. This paper explores an effective way to manage the truck traffic of export containers based on a time...... and the length of each time window. Finally, the model and the heuristic are tested using real data from a Chinese container terminal, and the result indicates that optimization of the time window can effectively flatten the peak traffic of export container trucks - one of the primary causes of road traffic...
Optimizing Time Windows For Managing Export Container Arrivals At Chinese Container Terminals
DEFF Research Database (Denmark)
Chen, Gang; Yang, Zhongzhen
2010-01-01
window management programme that is widely used in Chinese terminals to facilitate terminal and truck delivery operations. Firstly, the arrangement of time windows is assumed to follow the principle of minimizing transport costs. A cost function is defined that includes the costs of truck and driver...... waiting time, fuel consumption associated with truck idling, storage time of the containerized cargos and yard fee. Secondly, to minimize the total cost, a heuristic is developed based on a genetic algorithm to find a near optimal time window arrangement. The optimized solution involves the position...
Encoding M classical bits in the arrival time of dense-coded photons
Hegazy, Salem F; Obayya, Salah S A
2016-01-01
We present a scheme to encode M extra classical bits to a dense-coded pair of photons. By tuning the delay of an entangled pair of photons to one of 2^M time-bins and then applying one of the quantum dense coding protocols, a receiver equipped with a synchronized clock of reference is able to decode M bits (via classical time-bin encoding) + 2 bits (via quantum dense coding). This protocol, yet simple, does not dispense several special features of the used programmable delay apparatus to maintain the coherence of the two-photon state. While this type of time-domain encoding may be thought to be ideally of boundless photonic capacity (by increasing the number of available time-bins), errors due to the environmental noise and the imperfect devices and channel evolve with the number of time-bins.
Energy Technology Data Exchange (ETDEWEB)
Arsene, N.; Rebel, H.; Sima, O. [Institute of Space Science (ISS), Bucharest-Magurele, P.O. Box MG-23 (Romania) and Physics Department, University of Bucharest, Bucharest-Magurele (Romania); Karlsruhe Institute of Technology, Karlsruhe (Germany); Physics Department, University of Bucharest, Bucharest-Magurele (Romania)
2012-11-20
In this paper we study the possibility to discriminate the mass of the primary cosmic ray by observing the muon arrival times in ground detectors. We analyzed extensive air showers (EAS) induced by proton and iron nuclei with the same energy 8 Multiplication-Sign 10{sup 17} eV simulated with CORSIKA, and analyzed the muon arrival times at ground measured by the infill array detectors of the Pierre Auger Observatory (PAO). From the arrival times of the core and of the muons the atmospheric depth of muon generation locus is evaluated. The results suggest a potential mass discrimination on the basis of muon arrival times and of the reconstructed atmospheric depth of muon production. An analysis of a larger set of CORSIKA simulations carried out for primary energies above 10{sup 18} eV is in progress.
Lin, Mo; Li, Rui; Li, Jilin
2007-11-01
This paper deals with several key points including parameter estimation such as frequency of arrival (FOA), time of arrival (TOA) estimation algorithm and signal processing techniques in Medium-altitude Earth Orbit Local User Terminals (MEOLUT) based on Cospas-Sarsat Medium-altitude Earth Orbit Search and Rescue system (MEOSAR). Based on an analytical description of distress beacon, improved TOA and FOA estimation methods have been proposed. An improved FOA estimation method which integrates bi-FOA measurement, FFT method, Rife algorithm and Gaussian window is proposed to improve the accuracy of FOA estimation. In addition, TPD algorithm and signal correlation techniques are used to achieve a high performance of TOA estimation. Parameter estimation problems are solved by proposed FOA/TOA methods under quite poor Carrier-to-Noise (C/N0). A number of simulations are done to show the improvements. FOA and TOA estimation error are lower than 0.1Hz and 11μs respectively which is very high system requirement for MEOSAR system MEOLUT.
Directory of Open Access Journals (Sweden)
Syed Asif AliShah
2011-10-01
Full Text Available Load balancing is an efficient technique used to maximize throughput, optimal resource utilization, minimized response time and avoiding congestion. This can be achieved by distributing the workload evenly across two or more network stations, nodes or buffers, links, central processing units, hard drives, or other resources. In this paper, we have modeled and developed a load balancing approach in a discrete-time domain to analyze and evaluate the system of finite network buffers using an early arrival system. Our approach of modeling such a system consists of two steps. The first step is the determination of all system-state stages and their corresponding transition probabilities. Next, we compute various performance measures by utilizing the system state transition probabilities for its steady-state behavior.
Mainz, Roland E; Rossi, Giulio Maria; Cirmi, Giovanni; Yang, Yudong; Mücke, Oliver D; Kärtner, Franz X
2017-02-20
We introduce a simple all-inline variation of a balanced optical cross-correlator (BOC) that allows to measure the arrival time difference (ATD), over the full Nyquist bandwidth, with increased common-mode rejection and long-term stability. An FPGA-based signal processing unit allows for real-time signal normalization and enables locking to any setpoint with an unprecedented accuracy of 0.07 % within an increased ATD range of more than 400 fs, resulting in attosecond resolution locking. The setup precision is verified with an out-of-loop measurement to be less than 80 as residual jitter paving the way for highly demanding applications such as parametric waveform synthesizers.
The Option Value in Timing Derivative Trades
Drost, Feico; van der Heijden, T.G.E.; Werker, Bas
2015-01-01
Risk-neutral traders executing derivative trades on behalf of portfolio managers maximize their expected profit compared to trading at pre-determined times by timing trades, using the quickly changing risk exposures of derivative baskets. The optimal order submission strategy is a sequence of stop o
Smolt Condition and Timing of Arrival at Lower Granite Reservoir, 1988 Annual Report.
Energy Technology Data Exchange (ETDEWEB)
Buettner, Edwin W.; Nelson, William R.
1989-10-01
This project monitored the daily passage of smelts during the 1988 spring outmigration at two migrant traps; one each on the Snake and Clear-water rivers. Due to the low runoff year, chinook salmon catch at the Snake River trap was very low. Steelhead trout catch was higher than normal, probably due to trap modifications and because the trap was moved to the east side of the river. Chinook salmon and steelhead trout catch at the Clearwater River trap was similar to 1987. Total cumulative recovery of PIT tagged fish at the three dams, with PIT tag detection systems was: 55% for chinook salmon, 73% for hatchery steelhead trout, and 75% for wild steelhead trout. Travel time through Lower Granite Reservoir for PIT tagged chinook salmon and steelhead trout, marked at the head of the reservoir, was affected by discharge. Statistical analysis showed that as discharge increased from 40 kcfs to 80 kcfs, chinook salmon travel time decreased three fold, and steelhead trout travel time decreased two fold. There was a statistical difference between estimates of travel time through Lower Granite Reservoir for PIT tagged and freeze branded steelhead trout, but not for chinook salmon. These differences may be related to the estimation techniques used for PIT tagged and freeze branded groups, rather than real differences in travel time.
Smolt Condition and Timing of Arrival at Lower Granite Reservoir, 1987 Annual Report.
Energy Technology Data Exchange (ETDEWEB)
Buettner, Edwin W.; Nelson, V. Lance
1990-01-01
This project monitored the daily passage of smolts during the 1988 spring outmigration at two migrant traps; one each on the Snake and Clearwater rivers. Due to the low runoff year, chinook salmon catch at the Snake River trap was very low. Steelhead trout catch was higher than normal, probably due to trap modifications and because the trap was moved to the east side of the river. Chinook salmon and steelhead trout catch at the Clearwater River trap was similar to 1987. Total cumulative recovery of PIT tagged fish at the three dams, with PIT tag detection systems was: 55% for chinook salmon, 73% for hatchery steelhead trout, and 75% for wild steelhead trout. Travel time through Lower Granite Reservoir for PIT tagged chinook salmon and steelhead trout, marked at the head of the reservoir, was affected by discharge. Statistical analysis showed that as discharge increased from 40 kcfs to 80 kcfs, chinook salmon travel time decreased three fold, and steelhead trout travel time decreased two fold. There was a statistical difference between estimates of travel time through Lower Granite Reservoir for PIT tagged and freeze branded steelhead trout, but not for chinook salmon. These differences may be related to the estimation techniques used for PIT tagged and freeze branded groups, rather than real differences in travel time. 10 figs, 15 tabs.
Energy Technology Data Exchange (ETDEWEB)
Nie, You-Qi; Zhang, Jun, E-mail: zhangjun@ustc.edu.cn; Pan, Jian-Wei [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Hong-Fei; Wang, Jian [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Zhen; Ma, Xiongfeng [Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084 (China)
2014-02-03
We present a practical high-speed quantum random number generator, where the timing of single-photon detection relative to an external time reference is measured as the raw data. The bias of the raw data can be substantially reduced compared with the previous realizations. The raw random bit rate of our generator can reach 109 Mbps. We develop a model for the generator and evaluate the min-entropy of the raw data. Toeplitz matrix hashing is applied for randomness extraction, after which the final random bits are able to pass the standard randomness tests.
Nie, You-Qi; Zhang, Hong-Fei; Zhang, Zhen; Wang, Jian; Ma, Xiongfeng; Zhang, Jun; Pan, Jian-Wei
2014-02-01
We present a practical high-speed quantum random number generator, where the timing of single-photon detection relative to an external time reference is measured as the raw data. The bias of the raw data can be substantially reduced compared with the previous realizations. The raw random bit rate of our generator can reach 109 Mbps. We develop a model for the generator and evaluate the min-entropy of the raw data. Toeplitz matrix hashing is applied for randomness extraction, after which the final random bits are able to pass the standard randomness tests.
OPTIMIZING TIME WINDOWS FOR MANAGING ARRIVALS OF EXPORT CONTAINERS AT CHINESE CONTAINER TERMINALS
DEFF Research Database (Denmark)
Chen, Gang; Yang, Zhongzhen
2009-01-01
window management programme that is widely used in Chinese terminals to facilitate the terminal operations and the truck delivery operations. Firstly, the arrangement of time windows is assumed to follow the principle of minimizing the transport costs. A cost function is defined that includes the cost...
Underwater Localization by combining Time-of-Flight and Direction-of-Arrival
Kleunen, van Wouter A.P.; Blom, Koen C.H.; Meratnia, Nirvana; Kokkeler, André B.J.; Havinga, Paul J.M.; Smit, Gerard J.M.
2014-01-01
In this paper we present a combined ToF and DoA localization approach suitable for shallow underwater monitoring applications such as harbor monitoring. Our localization approach combines one-way ranging and DoA estimation to calculate both position and time-synchronization of the blind-node. We wil
ANALYSIS OF THE MACRO EXPERIMENT DATA TO COMPARE PARTICLE ARRIVAL TIMES UNDER GRAN SASSO
Directory of Open Access Journals (Sweden)
Francesco Ronga
2013-12-01
Full Text Available The claim of a neutrino velocity different from the speed of the light, made in September 2011 by the Opera experiment, suggested the study of the time delays between TeV underground muons in the Gran Sasso laboratory using the old data of the MACRO experiment, ended in 2000. This study can also give hints on new physics in the particle cascade produced by the interaction of a cosmic ray with the atmosphere.
DEFF Research Database (Denmark)
Hermansen, Cecilie; Møldrup, Per; Karup, Dan;
to give rapid and accurate predictions of soil functional properties related to texture and organic matter, such as water retention and compaction. We evaluated visNIR spectroscopy as a rapid and indirect method for predicting selected BTC tracer mass arrival times (TMATs) and the volumetric contents...... and volumetric contents of clay and mineral fines were correlated to spectral data with partial least squares regression on a calibration set (133 samples) and then tested on a validation set (44 samples). We obtained accurate visNIR predictions of the 5% TMAT and volumetric contents of clay and mineral fines....... VisNIR predictions of later TMATs of 10, 15, 20, 25, 30, 40 and 50% showed decreasing accuracy with increasing TMAT, which probably reflect decreasing correlation with soil texture....
Modeling inter-signal arrival times for accurate detection of CAN bus signal injection attacks
Energy Technology Data Exchange (ETDEWEB)
Moore, Michael Roy [ORNL; Bridges, Robert A [ORNL; Combs, Frank L [ORNL; Starr, Michael S [ORNL; Prowell, Stacy J [ORNL
2017-01-01
Modern vehicles rely on hundreds of on-board electronic control units (ECUs) communicating over in-vehicle networks. As external interfaces to the car control networks (such as the on-board diagnostic (OBD) port, auxiliary media ports, etc.) become common, and vehicle-to-vehicle / vehicle-to-infrastructure technology is in the near future, the attack surface for vehicles grows, exposing control networks to potentially life-critical attacks. This paper addresses the need for securing the CAN bus by detecting anomalous traffic patterns via unusual refresh rates of certain commands. While previous works have identified signal frequency as an important feature for CAN bus intrusion detection, this paper provides the first such algorithm with experiments on five attack scenarios. Our data-driven anomaly detection algorithm requires only five seconds of training time (on normal data) and achieves true positive / false discovery rates of 0.9998/0.00298, respectively (micro-averaged across the five experimental tests).
Tynell, Lena Lyngholt; Wimmelmann, Camilla Lawaetz; Jervelund, Signe Smith
2017-01-01
Objective: In most European countries, immigrants do not systematically learn about the host countries' healthcare system when arriving. This study investigated how newly arrived immigrants perceived the information they received about the Danish healthcare system. Methods: Immigrants attending a language school in Copenhagen in 2012 received…
Tynell, Lena Lyngholt; Wimmelmann, Camilla Lawaetz; Jervelund, Signe Smith
2017-01-01
Objective: In most European countries, immigrants do not systematically learn about the host countries' healthcare system when arriving. This study investigated how newly arrived immigrants perceived the information they received about the Danish healthcare system. Methods: Immigrants attending a language school in Copenhagen in 2012 received…
Ferdinandy, Bence; Abel, Daniel; Vicsek, Tamas; 10.1016/j.physa.2011.10.010
2012-01-01
Collective motion is abundant in nature, producing a vast amount of phenomena which have been studied in recent years, including the landing of flocks of birds. We investigate the collective decision making scenario where a flock of birds decides the optimal time of landing in the absence of a global leader. We introduce a simple phenomenological model in the spirit of the statistical mechanics-based self-propelled particles (SPP-s) approach to interpret this process. We expect that our model is applicable to a larger class of spatiotemporal decision making situations than just the landing of flocks (which process is used as a paradigmatic case). In the model birds are only influenced by observable variables, like position and velocity. Heterogeneity is introduced in the flock in terms of a depletion time after which a bird feels increasing bias to move towards the ground. Our model demonstrates a possible mechanism by which animals in a large group can arrive at an egalitarian decision about the time of swit...
Connecting speeds, directions and arrival times of 22 coronal mass ejections from the Sun to 1 AU
Möstl, C; Hall, J R; Liewer, P C; De Jong, E M; Colaninno, R C; Veronig, A M; Rollett, T; Temmer, M; Peinhart, V; Davies, J A; Lugaz, N; Liu, Y D; Farrugia, C J; Luhmann, J G; Vršnak, B; Harrison, R A; Galvin, A B
2014-01-01
Forecasting the in situ properties of coronal mass ejections (CMEs) from remote images is expected to strongly enhance predictions of space weather, and is of general interest for studying the interaction of CMEs with planetary environments. We study the feasibility of using a single heliospheric imager (HI) instrument, imaging the solar wind density from the Sun to 1 AU, for connecting remote images to in situ observations of CMEs. We compare the predictions of speed and arrival time for 22 CMEs (in 2008-2012) to the corresponding interplanetary coronal mass ejection (ICME) parameters at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). The list consists of front- and backsided, slow and fast CMEs (up to $2700 \\: km \\: s^{-1}$). We track the CMEs to $34.9 \\pm 7.1$ degrees elongation from the Sun with J-maps constructed using the SATPLOT tool, resulting in prediction lead times of $-26.4 \\pm 15.3$ hours. The geometrical models we use assume different CME front shapes (Fixed-$\\Phi$, Harmonic Mean, S...
Simulation-based validation and arrival-time correction for Patlak analyses of Perfusion-CT scans
Bredno, Jörg; Hom, Jason; Schneider, Thomas; Wintermark, Max
2009-02-01
Blood-brain-barrier (BBB) breakdown is a hypothesized mechanism for hemorrhagic transformation in acute stroke. The Patlak analysis of a Perfusion Computed Tomography (PCT) scan measures the BBB permeability, but the method yields higher estimates when applied to the first pass of the contrast bolus compared to a delayed phase. We present a numerical phantom that simulates vascular and parenchymal time-attenuation curves to determine the validity of permeability measurements obtained with different acquisition protocols. A network of tubes represents the major cerebral arteries ipsi- and contralateral to an ischemic event. These tubes branch off into smaller segments that represent capillary beds. Blood flow in the phantom is freely defined and simulated as non-Newtonian tubular flow. Diffusion of contrast in the vessels and permeation through vessel walls is part of the simulation. The phantom allows us to compare the results of a permeability measurement to the simulated vessel wall status. A Patlak analysis reliably detects areas with BBB breakdown for acquisitions of 240s duration, whereas results obtained from the first pass are biased in areas of reduced blood flow. Compensating for differences in contrast arrival times reduces this bias and gives good estimates of BBB permeability for PCT acquisitions of 90-150s duration.
Higher time derivatives, stability and Fermi Statistics
Lopez-Sarrion, Justo
2011-01-01
We show that statistics is crucial for the instability problem derived from higher time derivatives. In fact, and contrary to previous statements, we check that when dealing with Fermi systems, the Hamiltonian is well bounded and the quantum states are normalizable. Although, ghost states are still present, they do not affect unitarity under certain conditions. We first analyze a quantum oscillator involving Grassman variables and then we generalize it to a Dirac field. Finally, we discuss some physical implications
Energy Technology Data Exchange (ETDEWEB)
Ma, Jian; Casey, Cameron P.; Zheng, Xueyun; Ibrahim, Yehia M.; Wilkins, Christopher S.; Renslow, Ryan S.; Thomas, Dennis G.; Payne, Samuel H.; Monroe, Matthew E.; Smith, Richard D.; Teeguarden, Justin G.; Baker, Erin M.; Metz, Thomas O.
2017-05-15
Motivation: Drift tube ion mobility spectrometry (DTIMS) is increasingly implemented in high throughput omics workflows, and new informatics approaches are necessary for processing the associated data. To automatically extract arrival times for molecules measured by DTIMS coupled with mass spectrometry and compute their associated collisional cross sections (CCS) we created the PNNL Ion Mobility Cross Section Extractor (PIXiE). The primary application presented for this algorithm is the extraction of information necessary to create a reference library containing accu-rate masses, DTIMS arrival times and CCSs for use in high throughput omics analyses. Results: We demonstrate the utility of this approach by automatically extracting arrival times and calculating the associated CCSs for a set of endogenous metabolites and xenobiotics. The PIXiE-generated CCS values were identical to those calculated by hand and within error of those calcu-lated using commercially available instrument vendor software.
Directory of Open Access Journals (Sweden)
B.Sridevi
2012-06-01
Full Text Available The rapid growth of wireless communication and its persistent use influences all walks of life. Mobile WiMAX IEEE 802.16e standard enabled convergence of mobile and ﬁxed broadband networks through a common wide-area radio-access technology and ﬂexible network architecture. It aims to provide seamless support to its users but an inevitable is that the long delay which occurs during the handoff management in every network process. This paper proposes a Dynamic Interval based Processing Algorithm to separate ping-pong users from the pool of users and to process them separately thus reducing the overhead of network re-entry process. Incoming users are divided into three categories like new user, old user and ping pong user. New user should undergo all the phases of network entry process, old user is provided with authentication key which leads to skipping of steps in generation of keys. Proposed algorithm deals with identifying the ping pong users by calculating the inter arrival duration and rate with same base station. When assured authenticated ping-pong users enter the network next time within the allotted time they will be provided with last used Traffic Encryption Key (TEK thus bypassing key generation phase . It is observed that the proposed work performs the authentication phase and cancels the key generation phase which leads to minimum network entry delay and it saves to the maximum of 80% processing time. The network model was developed using Network Simulator and the algorithm was implemented in MATLAB GUIDE which gets connected to the database developed in MYSQL.This approach is justified through its timing analysis result which proves the efficient swift in the handoff processes.
Muehlsteff, J; Aubert, X A; Morren, G
2008-01-01
There is an unmet need for cuff-less blood pressure (BP) monitoring especially, in personal healthcare applications. The pulse arrival time (PAT) approach might offer a suitable solution to enable comfortable BP monitoring even at beat-level. However, the methodology is based on hemodynamic surrogate measures, which are sensitive to patient activities such as posture changes, not necessarily related to blood pressure variations. In this paper, we analyze the impact of posture on the PAT measure and related hemodynamic parameters such as the pre-ejection period in well-defined procedures. Additionally, the PAT of a monitored subject is investigated in an unsupervised scenario illustrating the complexity of such a measurement. Our results show the failure of blood pressure inference based on simple calibration strategies using the PAT measure only. We discuss opportunities to compensate for the observed effects towards the realization of wearable cuff-less blood pressure monitoring. These findings emphasize the importance of accessing context information in personal healthcare applications, where vital sign monitoring is typically unsupervised.
D'Alessandro, Antonino; Mangano, Giorgio; D'Anna, Giuseppe; Scudero, Salvatore
2016-12-01
Simultaneous inversion of P- and S-wave arrival times, collected during a 3-years Ocean Bottom Seismometer with Hydrophone (OBS/H) monitoring campaign, yields 1D P- and S-wave velocity models for the Ionian lithosphere (Central Mediterranean). The 1D model highlights the presence, in the Ionian upper mantle, of two layers characterized by high seismic P-wave velocity (S1 and S2, 6.3-6.7 and 7.5 km/s, respectively). These two layers, with thicknesses of about 3.3 km and 5 km, respectively, and ranging from ∼8 to ∼16 km in depth, are characterized by low S-wave velocity (S1 = 3.05-3.2 km/s, S2 = 3.85 km/s) and high values of VP/VS (S1 = 2.06-2.09, S2 = 1.95). This is a characteristic feature, often encountered in passive margins and is generally interpreted as partly serpentinized peridotite. The VP, VS and VP/VS values of S1 are consistent with 55-65% of serpentinization of the upper mantle, while the S2 ones are consistent with 15-25% of serpentinization. This research provides a crucial hint about the debated nature of the Ionian crust, suggesting its oceanic structure.
Time-delay and fractional derivatives
Tenreiro Machado JA
2011-01-01
This paper proposes the calculation of fractional algorithms based on time-delay systems. The study starts by analyzing the memory properties of fractional operators and their relation with time delay. Based on the Fourier analysis an approximation of fractional derivatives through time-delayed samples is developed. Furthermore, the parameters of the proposed approximation are estimated by means of genetic algorithms. The results demonstrate the feasibility of the new perspective.
Zhu, Jun; Assmann, R W.; Dohlus, M.; Dorda, U.; Marchetti, Barbara
2016-01-01
The generation of ultra-short electron bunches with ultra-small bunch arrival-time jitter is of vital importance for Laser-plasma wake field acceleration (LWFA) with external injection. We study the production of 100-MeV electron bunches with bunch durations of sub-femtosecond (fs) and bunch arrival-time jitters of less than 10 fs, in an S-band photoinjector by using a weak magnetic chicane with a slit collimator .The beam dynamics inside the chicane is simulated by using tw...
Quasi-Birth-and-Death Processes with Rational Arrival Process Components
DEFF Research Database (Denmark)
Bean, Nigel G.; Nielsen, Bo Friis
to develop an analytic method for such a process, that parallels the analysis of a traditional QBD. We demonstrate the analysis by considering a queue where the arrival process and the sequence of service times are derived from two different RAPs that are not just Markovian Arrival processes. We also......In this paper we introduce the concept of a Quasi-Birth-and-Death process (QBD) with Rational Arrival Process components. We use the physical interpretation of a Rational Arrival Process (RAP), developed by Asmussen and Bladt, to consider such a Markov process. We exploit this interpretation...... introduce an element of correlation between the arrival process and the sequence of service times....
Zheng, Yali; Poon, Carmen C Y; Yan, Bryan P; Lau, James Y W
2016-09-01
Ambulatory blood pressure monitoring (ABPM) has become an essential tool in the diagnosis and management of hypertension. Current standard ABPM devices use an oscillometric cuff-based method which can cause physical discomfort to the patients with repeated inflations and deflations, especially during nighttime leading to sleep disturbance. The ability to measure ambulatory BP accurately and comfortably without a cuff would be attractive. This study validated the accuracy of a cuff-less approach for ABPM using pulse arrival time (PAT) measurements on both healthy and hypertensive subjects for potential use in hypertensive management, which is the first of its kind. The wearable cuff-less device was evaluated against a standard cuff-based device on 24 subjects of which 15 have known hypertension. BP measurements were taken from each subject over a 24-h period by the cuff-less and cuff-based devices every 15 to 30 minutes during daily activities. Mean BP of each subject during daytime, nighttime and over 24-h were calculated. Agreement between mean nighttime systolic BP (SBP) and diastolic (DBP) measured by the two devices evaluated using Bland-Altman plot were -1.4 ± 6.6 and 0.4 ± 6.7 mmHg, respectively. Receiver operator characteristics (ROC) statistics was used to assess the diagnostic accuracy of the cuff-less approach in the detection of BP above the hypertension threshold during nighttime (>120/70 mmHg). The area under ROC curves were 0.975/0.79 for nighttime. The results suggest that PAT-based approach is accurate and promising for ABPM without the issue of sleep disturbances associated with cuff-based devices.
Real-time cosmography with redshift derivatives
Martins, C. J. A. P.; Martinelli, M.; Calabrese, E.; Ramos, M. P. L. P.
2016-08-01
The drift in the redshift of objects passively following the cosmological expansion has long been recognized as a key model-independent probe of cosmology. Here, we study the cosmological relevance of measurements of time or redshift derivatives of this drift, arguing that the combination of first and second redshift derivatives is a powerful test of the Λ CDM cosmological model. In particular, the latter can be obtained numerically from a set of measurements of the drift at different redshifts. We show that, in the low-redshift limit, a measurement of the derivative of the drift can provide a constraint on the jerk parameter, which is j =1 for flat Λ CDM , while generically j ≠1 for other models. We emphasize that such a measurement is well within the reach of the ELT-HIRES and SKA Phase 2 array surveys.
Real-time cosmography with redshift derivatives
Martins, C J A P; Calabrese, E; Ramos, M P L P
2016-01-01
The drift in the redshift of objects passively following the cosmological expansion has long been recognized as a key model-independent probe of cosmology. Here, we study the cosmological relevance of measurements of time or redshift derivatives of this drift, arguing that the combination of first and second redshift derivatives is a powerful test of the $\\Lambda$CDM cosmological model. In particular, the latter can be obtained numerically from a set of measurements of the drift at different redshifts. We show that, in the low-redshift limit, a measurement of the derivative of the drift can provide a constraint on the jerk parameter, which is $j=1$ for flat $\\Lambda$CDM, while generically $j\
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
A time-of-arrival(TOA) system based on GPS technology for locating VHF radiation sources from lightning has been developed and used in observation sites in the northern Shandong Province,China.The 3D images of the lightning progression have been obtained successfully for the first time in China.The 3D-channel evolutions of typical negative CG,positive CG and IC lightning flashes have been discussed together with the data of fast electric field change.It was found that significant differences existed between the negative and positive CG lightning flashes in terms of the initiation and propagation of the radiation sources.The preliminary breakdown of a negative CG lightning flash propagated at a speed about 5.2×104 m/s.The stepped leader of negative CG lightning flashes was trigged by negative initial breakdown.Thereafter,it propagated downward at a speed of 1.3×105 m/s.The initial process of the positive CG lightning flashes was also a propagation process of negative streamer.These streamers propagated dominantly horizontally in the positive charge region and accumulated positive charges at the origin of the lightning,and as a consequence,initiated downward positive streamers.A new type of lightning discharge that was triggered by a narrow bipolar pulse(NBP) is discussed in this study.The NBP was originated at altitude of about 10.5 km in the upper positive charge region.As a distinct difference from normal IC flash,its channels extended horizontally all around and produced a lot of radiation sources.The source power of the NBP could approach 16.7 kW,which is much greater than that of normal lightning discharge ranging between 100 mW and 500 W.The 3D propagation of this new type of lightning discharge was observed and obtained for the first time in China.The possible initiation mechanism of this new type of light-ning is discussed here.
Directory of Open Access Journals (Sweden)
Marina Gradišer
2015-01-01
Full Text Available The aim of our study was to determine whether diabetic ST segment elevation myocardial infarction (STEMI patients arrive in the emergency room (ER later than non-diabetics, compare the differences in pain quality and quantity between those groups, and measure differences in the outcome after an index hospitalization. A total of 266 patients with first presentation of STEMI were included in our study during a period of two years, 62 with diabetes and 204 without diabetes type 2. Pain intensity and quality at admission were measured using a McGill short form questionnaire. Diabetic patients did not arrive significantly later than non-diabetic (χ2; p = 0.105. Most diabetic patients described their pain as “slight” or “none” (χ2; p < 0.01, while most non-diabetic patients graded their pain as “moderate” or “severe” (χ2; p < 0.01. The quality of pain tended to be more distinct in non-diabetic patients, while diabetic patients reported mainly shortness of breath (χ2; p < 0.01. Diabetic patients were more likely to suffer a multi-vessel disease (χ2; p < 0.01, especially in the late arrival group. Therefore, cautious evaluation of diabetic patients and adequate education of target population could improve overall survival while well-organized care like a primary PCI Network program could significantly reduce CV mortality.
Kakimoto, F.; Tsuchimoto, I.; Enoki, T.; Suga, K.; Nishi, K.
1985-01-01
Detection of air showers with primary energies above 10 to the 19th power eV with sufficient statistics is extremely important in an astrophysical aspect related to the Greisen cut off and the origin of such high energy cosmic rays. Recently, a method is proposed to observe such giant air showers by measuring the arrival time distributions of air-shower particles at large core distances with a mini array. Experiments to measure the arrival time distributions of muons were started in 1981 and those of electrons in early 1983 in the Akeno air-shower array (930 gcm cm squared atmospheric depth, 900m above sea level). During the time of observation, the detection area of the Akeno array was expanded from 1 sq km to sq km in 1982 and to 20 sq km in 1984. Now the arrival time distribution of electrons and muons can be measured for showers with primary energies above 1019eV at large core distances.
Leon, J Diaz; Knecht, A; Miller, M L; Robertson, R G H; Schubert, A G
2011-01-01
We report results of air monitoring started due to the recent natural catastrophe on March 11, 2011 in Japan and the severe ensuing damage to the Fukushima nuclear reactor complex. On March 17-18, 2011 we detected the first arrival of the airborne fission products 131-I, 132-I, 132-Te, 134-Cs, and 137-Cs in Seattle, WA, USA, by identifying their characteristic gamma rays using a germanium detector. The highest detected activity to date is <~32 mBq/m^3 of 131-I.
Directory of Open Access Journals (Sweden)
Aleksandar Angelovski
2015-01-01
Full Text Available An evaluation of the cone-shaped pickup performance as a part of the high bandwidth bunch arrival-time monitors (BAMs for a low charge sub-10 fs arrival-time measurements is presented. Three sets of pickups are installed at the free electron laser FLASH at Deutsches Elektronen-Synchrotron, the quasi-cw SRF accelerator ELBE at the Helmholtz-Zentrum Dresden-Rossendorf and the SwissFEL injector test facility at Paul Scherrer Institute. Measurements and simulations are in good agreement and the pickups fulfill the design specifications. Utilizing the high bandwidth BAM with the cone-shaped pickups, an improvement of the signal slope by a factor of 10 is demonstrated at ELBE compared to the BAM with a low bandwidth.
Möstl, C; Lugaz, N; Farrugia, C J; Davies, J A; Temmer, M; Veronig, A M; Harrison, R; Crothers, S; Luhmann, J G; Galvin, A B; Zhang, T L; Baumjohann, W; Biernat, H K
2011-01-01
A goal of the NASA STEREO mission is to study the feasibility of forecasting the direction, arrival time and internal structure of solar coronal mass ejections (CMEs) from a vantage point outside the Sun-Earth line. Through a case study, we discuss the arrival time calculation of interplanetary CMEs (ICMEs) in the ecliptic plane using data from STEREO/SECCHI at large elongations from the Sun in combination with different geometric assumptions about the ICME front shape (Fixed-\\Phi (FP): a point and harmonic Mean (HM): a circle). These forecasting techniques use single-spacecraft imaging data and are based on the assumptions of constant velocity and direction. We show that for the slow (350 km/s) ICME on 2009 February 13-18, observed at quadrature by the two STEREO spacecraft, the results for the arrival time given by the HM approximation are more accurate by 12 hours than those for FP in comparison to in situ observations of solar wind plasma and magnetic field parameters by STEREO/IMPACT/PLASTIC, and by 6 ho...
Energy Technology Data Exchange (ETDEWEB)
Hess, Phillip; Zhang, Jie, E-mail: phess4@gmu.edu [School of Physics, Astronomy and Computational Sciences, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States)
2014-09-01
We present a detailed study of the complete evolution of a coronal mass ejection (CME). We have tracked the evolution of both the ejecta and its shock, and further fit the evolution of the fronts to a simple but physics-based analytical model. This study focuses on the CME initiated on the Sun on 2012 July 12 and arriving at the Earth on 2012 July 14. Shock and ejecta fronts were observed by white light images, as well as in situ by the Advanced Composition Explorer satellite. We find that the propagation of the two fronts is not completely dependent upon one another, but can each be modeled in the heliosphere with a drag model that assumes the dominant force of affecting CME evolution to be the aerodynamic drag force of the ambient solar wind. Results indicate that the CME ejecta front undergoes a more rapid deceleration than the shock front within 50 R {sub ☉} and therefore the propagation of the two fronts is not completely coupled in the heliosphere. Using the graduated cylindrical shell model, as well as data from time-elongation stack plots and in situ signatures, we show that the drag model can accurately describe the behavior of each front, but is more effective with the ejecta. We also show that without the in situ data, based on measurements out to 80 R {sub ☉} combined with the general values for drag model parameters, the arrival of both the shock and ejecta can be predicted within four hours of arrival.
Castellaro, Marco; Peruzzo, Denis; Mehndiratta, Amit; Pillonetto, Gianluigi; Petersen, Esben Thade; Golay, Xavier; Chappell, Michael A; Bertoldo, Alessandra
2015-12-01
QUASAR arterial spin labeling (ASL) permits the application of deconvolution approaches for the absolute quantification of cerebral perfusion. Currently, oscillation index regularized singular value decomposition (oSVD) combined with edge-detection (ED) is the most commonly used method. Its major drawbacks are nonphysiological oscillations in the impulse response function and underestimation of perfusion. The aim of this work is to introduce a novel method to overcome these limitations. A system identification method, stable spline (SS), was extended to address ASL peculiarities such as the delay in arrival of the arterial blood in the tissue. The proposed framework was compared with oSVD + ED in both simulated and real data. SS was used to investigate the validity of using a voxel-wise tissue T1 value instead of using a single global value (of blood T1 ). SS outperformed oSVD + ED in 79.9% of simulations. When applied to real data, SS exhibited a physiologically realistic range for perfusion and a higher mean value with respect to oSVD + ED (55.5 ± 9.5 SS, 34.9 ± 5.2 oSVD + ED mL/100 g/min). SS can represent an alternative to oSVD + ED for the quantification of QUASAR ASL data. Analysis of the retrieved impulse response function revealed that using a voxel wise tissue T1 might be suboptimal. © 2014 Wiley Periodicals, Inc.
Zhu, J.; Assmann, R. W.; Dohlus, M.; Dorda, U.; Marchetti, B.
2016-05-01
The generation of ultrashort electron bunches with ultrasmall bunch arrival-time jitter is of vital importance for laser-plasma wakefield acceleration with external injection. We study the production of 100-MeV electron bunches with bunch durations of subfemtosecond (fs) and bunch arrival-time jitters of less than 10 fs, in an S-band photoinjector by using a weak magnetic chicane with a slit collimator. The beam dynamics inside the chicane is simulated by using two codes with different self-force models. The first code separates the self-force into a three-dimensional (3D) quasistatic space-charge model and a one-dimensional coherent synchrotron radiation (CSR) model, while the other one starts from the first principle with a so-called 3D sub-bunch method. The simulations indicate that the CSR effect dominates the horizontal emittance growth and the 1D CSR model underestimates the final bunch duration and emittance because of the very large transverse-to-longitudinal aspect ratio of the sub-fs bunch. Particularly, the CSR effect is also strongly affected by the vertical bunch size. Due to the coupling between the horizontal and longitudinal phase spaces, the bunch duration at the entrance of the last dipole magnet of the chicane is still significantly longer than that at the exit of the chicane, which considerably mitigates the impact of space charge and CSR effects on the beam quality. Exploiting this effect, a bunch charge of up to 4.8 pC in a sub-fs bunch could be simulated. In addition, we analytically and numerically investigate the impact of different jitter sources on the bunch arrival-time jitter downstream of the chicane, and define the tolerance budgets assuming realistic values of the stability of the linac for different bunch charges and compression schemes.
Directory of Open Access Journals (Sweden)
J. Zhu
2016-05-01
Full Text Available The generation of ultrashort electron bunches with ultrasmall bunch arrival-time jitter is of vital importance for laser-plasma wakefield acceleration with external injection. We study the production of 100-MeV electron bunches with bunch durations of subfemtosecond (fs and bunch arrival-time jitters of less than 10 fs, in an S-band photoinjector by using a weak magnetic chicane with a slit collimator. The beam dynamics inside the chicane is simulated by using two codes with different self-force models. The first code separates the self-force into a three-dimensional (3D quasistatic space-charge model and a one-dimensional coherent synchrotron radiation (CSR model, while the other one starts from the first principle with a so-called 3D sub-bunch method. The simulations indicate that the CSR effect dominates the horizontal emittance growth and the 1D CSR model underestimates the final bunch duration and emittance because of the very large transverse-to-longitudinal aspect ratio of the sub-fs bunch. Particularly, the CSR effect is also strongly affected by the vertical bunch size. Due to the coupling between the horizontal and longitudinal phase spaces, the bunch duration at the entrance of the last dipole magnet of the chicane is still significantly longer than that at the exit of the chicane, which considerably mitigates the impact of space charge and CSR effects on the beam quality. Exploiting this effect, a bunch charge of up to 4.8 pC in a sub-fs bunch could be simulated. In addition, we analytically and numerically investigate the impact of different jitter sources on the bunch arrival-time jitter downstream of the chicane, and define the tolerance budgets assuming realistic values of the stability of the linac for different bunch charges and compression schemes.
Arrival Metering Precision Study
Prevot, Thomas; Mercer, Joey; Homola, Jeffrey; Hunt, Sarah; Gomez, Ashley; Bienert, Nancy; Omar, Faisal; Kraut, Joshua; Brasil, Connie; Wu, Minghong, G.
2015-01-01
This paper describes the background, method and results of the Arrival Metering Precision Study (AMPS) conducted in the Airspace Operations Laboratory at NASA Ames Research Center in May 2014. The simulation study measured delivery accuracy, flight efficiency, controller workload, and acceptability of time-based metering operations to a meter fix at the terminal area boundary for different resolution levels of metering delay times displayed to the air traffic controllers and different levels of airspeed information made available to the Time-Based Flow Management (TBFM) system computing the delay. The results show that the resolution of the delay countdown timer (DCT) on the controllers display has a significant impact on the delivery accuracy at the meter fix. Using the 10 seconds rounded and 1 minute rounded DCT resolutions resulted in more accurate delivery than 1 minute truncated and were preferred by the controllers. Using the speeds the controllers entered into the fourth line of the data tag to update the delay computation in TBFM in high and low altitude sectors increased air traffic control efficiency and reduced fuel burn for arriving aircraft during time based metering.
2015-01-01
As a follow-up to a recent study in the spin-0 case [J. Bunao and E. A. Galapon, Ann. Phys. 353, 83-106 (2015)], we construct a one-particle Time of Arrival (TOA) operator conjugate to a Hamiltonian describing a free relativistic spin-1/2 particle in one spatial dimension. Upon transformation in a representation where the Hamiltonian is diagonal, it turns out that the constructed operator consists of an operator term $\\mathcal{\\hat{T}}$ whose action is the same as in the spin-0 case, and anot...
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NAUWELAERS, B.
2010-05-01
Full Text Available This paper introduces the technology Time of Arrival (TOA based on chirp pulses (according to IEEE 802.15.4a as a means to perform localization in Wireless Sensor Networks (WSN's active at 2.4 GHz. Advantages and disadvantages of the technology are discussed and act as a guideline for improving localization accuracy. Tests concerning TOA are performed by means of the location engine of Nanotron. Adapting this engine leads to improved localization results. It is shown that TOA measurements are susceptible to reflections and dynamic environments.
Lourenco, Pedro M.; Kentie, Rosemarie; Schroeder, Julia; Groen, Niko M.; Piersma, Theunis; Bairlein, F.; Hooijmeijer, Jos C.E.W.
2011-01-01
When early breeding is advantageous, migrants underway to the breeding areas may be time stressed. The timing of sequential events such as migration and breeding is expected to be correlated because of a "domino effect", and would be of particular biological importance if timings are repeatable
Ma, Jian; Casey, Cameron P; Zheng, Xueyun; Ibrahim, Yehia M; Wilkins, Christopher S; Renslow, Ryan S; Thomas, Dennis G; Payne, Samuel H; Monroe, Matthew E; Smith, Richard D; Teeguarden, Justin G; Baker, Erin S; Metz, Thomas O
2017-09-01
Drift tube ion mobility spectrometry coupled with mass spectrometry (DTIMS-MS) is increasingly implemented in high throughput omics workflows, and new informatics approaches are necessary for processing the associated data. To automatically extract arrival times for molecules measured by DTIMS at multiple electric fields and compute their associated collisional cross sections (CCS), we created the PNNL Ion Mobility Cross Section Extractor (PIXiE). The primary application presented for this algorithm is the extraction of data that can then be used to create a reference library of experimental CCS values for use in high throughput omics analyses. We demonstrate the utility of this approach by automatically extracting arrival times and calculating the associated CCSs for a set of endogenous metabolites and xenobiotics. The PIXiE-generated CCS values were within error of those calculated using commercially available instrument vendor software. PIXiE is an open-source tool, freely available on Github. The documentation, source code of the software, and a GUI can be found at https://github.com/PNNL-Comp-Mass-Spec/PIXiE and the source code of the backend workflow library used by PIXiE can be found at https://github.com/PNNL-Comp-Mass-Spec/IMS-Informed-Library . erin.baker@pnnl.gov or thomas.metz@pnnl.gov. Supplementary data are available at Bioinformatics online.
Energy Technology Data Exchange (ETDEWEB)
Chavez, Marcus Alexander; Willis, Michael David; Covert, Timothy Todd
2014-09-01
The miniaturization of explosive components has driven the need for a corresponding miniaturization of the current diagnostic techniques available to measure the explosive phenomena. Laser interferometry and the use of spectrally coated optical windows have proven to be an essential interrogation technique to acquire particle velocity time history data in one- dimensional gas gun and relatively large-scale explosive experiments. A new diagnostic technique described herein allows for experimental measurement of apparent particle velocity time histories in microscale explosive configurations and can be applied to shocks/non-shocks in inert materials. The diagnostic, Embedded Fiber Optic Sensors (EFOS), has been tested in challenging microscopic experimental configurations that give confidence in the technique's ability to measure the apparent particle velocity time histories of an explosive with pressure outputs in the tenths of kilobars to several kilobars. Embedded Fiber Optic Sensors also allow for several measurements to be acquired in a single experiment because they are microscopic, thus reducing the number of experiments necessary. The future of EFOS technology will focus on further miniaturization, material selection appropriate for the operating pressure regime, and extensive hydrocode and optical analysis to transform apparent particle velocity time histories into true particle velocity time histories as well as the more meaningful pressure time histories.
Kakimoto, F.; Tsuchimoto, I.; Enoki, T.; Suga, K.; Nishi, K.
1985-01-01
The arrival time distributions of muons with energies above 1.0GeV and 0.5GeV have been measured in the Akeno air-shower array to study the longitudinal development of muons in air showers with primary energies in the range 10 to the 17th power to 10 to the 18th power ev. The average rise times of muons with energies above 1.0GeV at large core distances are consistent with those expected from very high multiplicity models and, on the contrary, with those expected from the low multiplicity models at small core distances. This implies that the longitudinal development at atmospheric depth smaller than 500 cm square is very fast and that at larger atmospheric depths is rather slow.
Wang, Lin; Huang, Tianyi; Li, Xiang; 10.1103/PhysRevE.86.032901
2012-01-01
With a simple phenomenological metapopulation model, which characterizes the invasion process of an influenza pandemic from a source to a subpopulation at risk, we compare the efficiency of inter- and intra-population interventions in delaying the arrival of an influenza pandemic. We take travel restriction and patient isolation as examples, since in reality they are typical control measures implemented at the inter- and intra-population levels, respectively. We find that the intra-population interventions, e.g., patient isolation, perform better than the inter-population strategies such as travel restriction if the response time is small. However, intra-population strategies are sensitive to the increase of the response time, which might be inevitable due to socioeconomic reasons in practice and will largely discount the efficiency.
Wang, Lin; Zhang, Yan; Huang, Tianyi; Li, Xiang
2012-09-01
With a simple phenomenological metapopulation model, which characterizes the invasion process of an influenza pandemic from a source to a subpopulation at risk, we compare the efficiency of inter- and intrapopulation interventions in delaying the arrival of an influenza pandemic. We take travel restriction and patient isolation as examples, since in reality they are typical control measures implemented at the inter- and intrapopulation levels, respectively. We find that the intrapopulation interventions, e.g., patient isolation, perform better than the interpopulation strategies such as travel restriction if the response time is small. However, intrapopulation strategies are sensitive to the increase of the response time, which might be inevitable due to socioeconomic reasons in practice and will largely discount the efficiency.
Directory of Open Access Journals (Sweden)
María Inés Zaldívar Ovalle
2014-11-01
Full Text Available In the context of the Relación, by Francisco de Borja y Aragón, this paper will report on the exploratory travels —named Arrival and Conquests— of Spanish encomenderos and soldiers between 1615 and 1621. In this context, the present study highlights some of the difficulties Esquilache faced in the exercise of power as head of the Viceroyalty of Peru. We focus our attention on the specific event named Spanish Government. The reasons discussed this time, are closely related to the battle between soldiers and trustees to obtain personal profit. The latter was a current struggle, dating from the origins of the viceroyalty. However, at the time of the events, such conflicts had worsened due to a complex political and economic situation.
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R. Tondi
2004-06-01
Full Text Available We performed an analysis of refraction data recorded in Italy since 1968 in the frame of the numerous deep seismic sounding and wide-angle reflection/refraction projects. The aims of this study are to construct a parametric database including the recording geometric information relative to each profile, the phase pickings and the results of some kinematic analyses performed on the data, and to define a reference 1D velocity model for the Italian territory from all the available refraction data. As concerns the first goal, for each seismic section we picked the P-wave first-arrival-times, evaluated the uncertainties of the arrival-times pickings and determined from each travel time-offset curve the 1D velocity model. The study was performed on 419 seismic sections. Picking was carried out manually by an algorithm which includes the computation of three picking functions and the picking- error estimation. For each of the travel time-offset curves a 1D velocity model has been calculated. Actually, the 1D velocity-depth functions were estimated in three different ways which assume: a constant velocitygradient model, a varying velocity-gradient model and a layered model. As regards the second objective of this work, a mean 1D velocity model for the Italian crust was defined and compared with those used for earthquake hypocentre locations and seismic tomographic studies by different institutions operating in the Italian area, to assess the significance of the model obtained. This model can be used in future works as input for a next joint tomographic inversion of active and passive seismic data.
Girish, B. S.; Pandey, Deepak; Ramachandran, Hema
2017-08-01
We present a compact, inexpensive multichannel module, APODAS (Avalanche Photodiode Output Data Acquisition System), capable of detecting 0.8 billion photons per second and providing real-time recording on a computer hard-disk, of channel- and time-tagged information of the arrival of upto 0.4 billion photons per second. Built around a Virtex-5 Field Programmable Gate Array (FPGA) unit, APODAS offers a temporal resolution of 5 nanoseconds with zero deadtime in data acquisition, utilising an efficient scheme for time and channel tagging and employing Gigabit ethernet for the transfer of data. Analysis tools have been developed on a Linux platform for multi-fold coincidence studies and time-delayed intensity interferometry. As illustrative examples, the second-order intensity correlation function ( g 2) of light from two commonly used sources in quantum optics —a coherent laser source and a dilute atomic vapour emitting spontaneously, constituting a thermal source— are presented. With easy reconfigurability and with no restriction on the total record length, APODAS can be readily used for studies over various time scales. This is demonstrated by using APODAS to reveal Rabi oscillations on nanosecond time scales in the emission of ultracold atoms, on the one hand, and, on the other hand, to measure the second-order correlation function on the millisecond time scales from tailored light sources. The efficient and versatile performance of APODAS promises its utility in diverse fields, like quantum optics, quantum communication, nuclear physics, astrophysics and biology.
Lloyd, S. M.; van der Lee, S.; Assumpcao, M.; Rocha, M. P.; Vandecar, J. C.
2010-12-01
We combine receiver function constraints on crustal thickness, Rayleigh wave group velocities, regional S wave trains, and teleseismic S delays to jointly invert for the S-velocity structure of central South America. Previous studies using the teleseismic delay times have outlined 1) a long, strong high-velocity anomaly typical of subducting oceanic lithosphere beneath the central part of the Central Andes, and 2) a deeper, uppermost lower-mantle high-velocity anomalie beneath southeastern Brazil. Using the other above data sets, which constrain the upper mantle between the two regions, we connect the two tomographic models through the mentioned joint inversion of the combined data sets. We investigate whether the lower-mantle high velocity anomaly beneath southeastern Brazil is possibly the extension of the the high-velocity anomaly representing the subducting Nazca Plate between the Central Andes and whether any portion of the deep slab may be relatively flat around the mid-mantle transition region, allowing it to reach to beneath the continent's opposing, passive margin within the top 1000 km of the mantle. This reach could in turn lead to interesting mantle and passive-margin dynamics through the cycling of deeply subducted water. We will conclude with a comparison with North America, where past subduction at shallow dip angles (during the Laramide) may have led to flat slab segments in the transition zone. Thermo-kinetic modeling has shown that the same chunk of oceanic lithosphere was involved in both cases of "flatness", having slowed the slab's progression into the lower mantle and facilitating slab deformation within the transition zone.
Wang, Minggang
2016-01-01
Understanding of aboveground (AG) and belowground (BG) herbivore interactions has substantially advanced over the last decades. AG and BG herbivores are spatially separated, but can interact via their shared host plant. Foliar damage by AG herbivores can cause changes in root growth or root chemistr
Rucker, Dale F.; Ferré, Ty P. A.
2004-08-01
A MATLAB program was developed to invert first arrival travel time picks from zero offset profiling borehole ground penetrating radar traces to obtain the electromagnetic wave propagation velocities in soil. Zero-offset profiling refers to a mode of operation wherein the centers of the bistatic antennae being lowered to the same depth below ground for each measurement. The inversion uses a simulated annealing optimization routine, whereby the model attempts to reduce the root mean square error between the measured and modeled travel time by perturbing the velocity in a ray tracing routine. Measurement uncertainty is incorporated through the presentation of the ensemble mean and standard deviation from the results of a Monte Carlo simulation. The program features a pre-processor to modify or delete travel time information from the profile before inversion and post-processing through presentation of the ensemble statistics of the water contents inferred from the velocity profile. The program includes a novel application of a graphical user interface to animate the velocity fitting routine.
MARKOVIAN QUEUES WITH CORRELATED ARRIVAL PROCESSES
Hunter, Jeffrey J.
2007-01-01
In an attempt to examine the effect of dependencies in the arrival process on the steady state queue length process in single server queueing models with exponential service time distribution, four different models for the arrival process, each with marginally distributed exponential inter-arrivals to the queueing system, are considered. Two of these models are based upon the upper and lower bounding joint distribution functions given by the Fréchet bounds for bivariate distributions with spe...
Rawles, Christopher; Thurber, Clifford
2015-08-01
We present a simple, fast, and robust method for automatic detection of P- and S-wave arrivals using a nearest neighbours-based approach. The nearest neighbour algorithm is one of the most popular time-series classification methods in the data mining community and has been applied to time-series problems in many different domains. Specifically, our method is based on the non-parametric time-series classification method developed by Nikolov. Instead of building a model by estimating parameters from the data, the method uses the data itself to define the model. Potential phase arrivals are identified based on their similarity to a set of reference data consisting of positive and negative sets, where the positive set contains examples of analyst identified P- or S-wave onsets and the negative set contains examples that do not contain P waves or S waves. Similarity is defined as the square of the Euclidean distance between vectors representing the scaled absolute values of the amplitudes of the observed signal and a given reference example in time windows of the same length. For both P waves and S waves, a single pass is done through the bandpassed data, producing a score function defined as the ratio of the sum of similarity to positive examples over the sum of similarity to negative examples for each window. A phase arrival is chosen as the centre position of the window that maximizes the score function. The method is tested on two local earthquake data sets, consisting of 98 known events from the Parkfield region in central California and 32 known events from the Alpine Fault region on the South Island of New Zealand. For P-wave picks, using a reference set containing two picks from the Parkfield data set, 98 per cent of Parkfield and 94 per cent of Alpine Fault picks are determined within 0.1 s of the analyst pick. For S-wave picks, 94 per cent and 91 per cent of picks are determined within 0.2 s of the analyst picks for the Parkfield and Alpine Fault data set
National Oceanic and Atmospheric Administration, Department of Commerce — The Vessel Arrival Info is a spreadsheet that gets filled out during the initial stage of the debriefing process by the debriefer. It contains vessel name, trip...
Time of arrival estimation based on improved teager-kaiser operator%基于改进Teager-Kaiser算子的来波时间估计
Institute of Scientific and Technical Information of China (English)
刘立红; 冷文; 王安国
2014-01-01
Teager-Kaiser (TK)算子对噪声比较敏感,当噪声存在时,TK算法对信号到达时间(time of Arrival,TOA)的估计精度比较低,结合多径信道特点,对TK算子进行了改进.改进算法通过对相关曲线进行高次方累积,增大相关曲线中TOA点对应的输出值,从而降低噪声对输出信号的影响,提高了TOA的估计精度,同时根据TOA点所对应相关曲线的位置特性,限定信号数据范围,不仅可以有效地降低改进算法的计算复杂度,还可以进一步提高TOA的估计精度.对多径信道模型的仿真结果表明,该改进算法对TOA估计的精度明显优于TK算法,特别是在噪声比较严重的情况下,TOA估计精度得到很大的提高.
Directory of Open Access Journals (Sweden)
Xiaoli Wang
Full Text Available Serfling-type periodic regression models have been widely used to identify and analyse epidemic of influenza. In these approaches, the baseline is traditionally determined using cleaned historical non-epidemic data. However, we found that the previous exclusion of epidemic seasons was empirical, since year-year variations in the seasonal pattern of activity had been ignored. Therefore, excluding fixed 'epidemic' months did not seem reasonable. We made some adjustments in the rule of epidemic-period removal to avoid potentially subjective definition of the start and end of epidemic periods. We fitted the baseline iteratively. Firstly, we established a Serfling regression model based on the actual observations without any removals. After that, instead of manually excluding a predefined 'epidemic' period (the traditional method, we excluded observations which exceeded a calculated boundary. We then established Serfling regression once more using the cleaned data and excluded observations which exceeded a calculated boundary. We repeated this process until the R2 value stopped to increase. In addition, the definitions of the onset of influenza epidemic were heterogeneous, which might make it impossible to accurately evaluate the performance of alternative approaches. We then used this modified model to detect the peak timing of influenza instead of the onset of epidemic and compared this model with traditional Serfling models using observed weekly case counts of influenza-like illness (ILIs, in terms of sensitivity, specificity and lead time. A better performance was observed. In summary, we provide an adjusted Serfling model which may have improved performance over traditional models in early warning at arrival of peak timing of influenza.
Wang, Xiaoli; Wu, Shuangsheng; MacIntyre, C Raina; Zhang, Hongbin; Shi, Weixian; Peng, Xiaomin; Duan, Wei; Yang, Peng; Zhang, Yi; Wang, Quanyi
2015-01-01
Serfling-type periodic regression models have been widely used to identify and analyse epidemic of influenza. In these approaches, the baseline is traditionally determined using cleaned historical non-epidemic data. However, we found that the previous exclusion of epidemic seasons was empirical, since year-year variations in the seasonal pattern of activity had been ignored. Therefore, excluding fixed 'epidemic' months did not seem reasonable. We made some adjustments in the rule of epidemic-period removal to avoid potentially subjective definition of the start and end of epidemic periods. We fitted the baseline iteratively. Firstly, we established a Serfling regression model based on the actual observations without any removals. After that, instead of manually excluding a predefined 'epidemic' period (the traditional method), we excluded observations which exceeded a calculated boundary. We then established Serfling regression once more using the cleaned data and excluded observations which exceeded a calculated boundary. We repeated this process until the R2 value stopped to increase. In addition, the definitions of the onset of influenza epidemic were heterogeneous, which might make it impossible to accurately evaluate the performance of alternative approaches. We then used this modified model to detect the peak timing of influenza instead of the onset of epidemic and compared this model with traditional Serfling models using observed weekly case counts of influenza-like illness (ILIs), in terms of sensitivity, specificity and lead time. A better performance was observed. In summary, we provide an adjusted Serfling model which may have improved performance over traditional models in early warning at arrival of peak timing of influenza.
Morgenstern, Uwe; Daughney, Christopher J.; Stewart, Michael K.; McDonnell, Jeffrey J.
2013-04-01
, most of the water inflows into the lake are not yet fully representing the nitrate loading in their sub-catchments from current land use practises. These water inflows are still 'diluted' by pristine old water, but over time, the full amount of nitrate load will arrive at the lake. With the age distribution parameters, it is possible to predict the increase in nitrate load to the lake via the groundwater discharges. All sub-catchments have different mean transit times. The mean transit times are not necessarily correlated with observable hydrogeologic properties like hydraulic conductivity and catchment size. Without such age tracer data, it is therefore difficult to predict mean transit times (lag times, memory) of water transfer through catchments. References: Stewart, M.K., Morgenstern, U., McDonnell, J.J., Pfister, L. (2012). The 'hidden streamflow' challenge in catchment hydrology: A call to action for streamwater transit time analysis. Hydrol. Process. 26,2061-2066, Invited commentary. DOI: 10.1002/hyp.9262 Morgenstern, U., Stewart, M.K., and Stenger, R. (2010) Dating of streamwater using tritium in a post nuclear bomb pulse world: continuous variation of mean transit time with streamflow, Hydrol. Earth Syst. Sci, 14, 2289-2301
WAKUI, NORITAKA; TAKAYAMA, RYUJI; KAMIYAMA, NAOHISA; KOBAYASHI, KOJIRO; MATSUI, DAIGO; MATSUKIYO, YASUSHI; KANEKAWA, TAKENORI; IKEHARA, TAKASHI; ISHII, KOJI; SUMINO, YASUKIYO
2013-01-01
It is considered difficult to make a definitive diagnosis of focal nodular hyperplasia (FNH) of <3 cm when using conventional diagnostic imaging modalities. Typical FNH imaging findings are: i) central scar formation, ii) nutrient vessels extending radially from the center and iii) the presence of Kupffer cells. In a clinical setting, identification of a spoke-wheel pattern formed by nutrient vessels extending radially is a key feature in the diagnosis of FNH. In this study, we investigated the detection rate of spoke-wheel patterns of FNH <3 cm using arrival time parametric imaging (At-PI) technology with Sonazoid-enhanced ultrasonography (US). Five patients with FNH <3 cm who had undergone Sonazoid-enhanced US at the Toho University Omori Medical Center between February 2008 and March 2009 were included in the study. The mean tumor diameter was 20.2±7.2 mm. Lesions were enhanced with 0.5 ml Sonazoid US contrast agent and a video of the procedure was saved and used for At-PI analysis of contrast agent dynamics in FNH. Three ultrasonographic specialists examined the images and made a diagnosis of FNH based on the findings of spoke-wheel patterns. Similarly, micro-flow imaging (MFI) was performed to evaluate the contrast agent dynamics in FNH. Using MFI, FNH was diagnosed in 3 of the 5 cases by the three specialists, whereas At-PI enabled the identification of spoke-wheel patterns in all 5 cases. At-PI using Sonazoid-enhanced US is superior for detecting spoke-wheel patterns of FNH <3 cm. PMID:23837029
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M.V.Rama Sundari
2011-09-01
Full Text Available Communication network models play a predominant role in performance evaluation of many communication systems. The packet arrival processes for data networks are not matching with the Poisson processes due to the nature of bursty and time dependent arrivals. In this paper, a three node communication network model with non homogeneous Poisson arrivals having dynamic bandwidth allocation under modified phase type transmission is introduced for performance evaluation and monitoring of several tele and satellite communications. The system performance measures of the network are derived explicitly. The sensitivity analysis reveals the dynamic bandwidth allocation strategy and non homogeneous Poisson arrivals can reduce the burstyness in buffers and delay in transmission. This model also includes some of the earlier models as particular cases for specific and limiting of parameters.
Inferring time derivatives including cell growth rates using Gaussian processes
Swain, Peter S.; Stevenson, Keiran; Leary, Allen; Montano-Gutierrez, Luis F.; Clark, Ivan B. N.; Vogel, Jackie; Pilizota, Teuta
2016-12-01
Often the time derivative of a measured variable is of as much interest as the variable itself. For a growing population of biological cells, for example, the population's growth rate is typically more important than its size. Here we introduce a non-parametric method to infer first and second time derivatives as a function of time from time-series data. Our approach is based on Gaussian processes and applies to a wide range of data. In tests, the method is at least as accurate as others, but has several advantages: it estimates errors both in the inference and in any summary statistics, such as lag times, and allows interpolation with the corresponding error estimation. As illustrations, we infer growth rates of microbial cells, the rate of assembly of an amyloid fibril and both the speed and acceleration of two separating spindle pole bodies. Our algorithm should thus be broadly applicable.
Zhang, H.; Fang, H.; Yao, H.; Maceira, M.; van der Hilst, R. D.
2014-12-01
Recently, Zhang et al. (2014, Pure and Appiled Geophysics) have developed a joint inversion code incorporating body-wave arrival times and surface-wave dispersion data. The joint inversion code was based on the regional-scale version of the double-difference tomography algorithm tomoDD. The surface-wave inversion part uses the propagator matrix solver in the algorithm DISPER80 (Saito, 1988) for forward calculation of dispersion curves from layered velocity models and the related sensitivities. The application of the joint inversion code to the SAFOD site in central California shows that the fault structure is better imaged in the new model, which is able to fit both the body-wave and surface-wave observations adequately. Here we present a new joint inversion method that solves the model in the wavelet domain constrained by sparsity regularization. Compared to the previous method, it has the following advantages: (1) The method is both data- and model-adaptive. For the velocity model, it can be represented by different wavelet coefficients at different scales, which are generally sparse. By constraining the model wavelet coefficients to be sparse, the inversion in the wavelet domain can inherently adapt to the data distribution so that the model has higher spatial resolution in the good data coverage zone. Fang and Zhang (2014, Geophysical Journal International) have showed the superior performance of the wavelet-based double-difference seismic tomography method compared to the conventional method. (2) For the surface wave inversion, the joint inversion code takes advantage of the recent development of direct inversion of surface wave dispersion data for 3-D variations of shear wave velocity without the intermediate step of phase or group velocity maps (Fang et al., 2014, Geophysical Journal International). A fast marching method is used to compute, at each period, surface wave traveltimes and ray paths between sources and receivers. We will test the new joint
Hoffman, Adam J.; Lee, John C.
2016-02-01
A new time-dependent Method of Characteristics (MOC) formulation for nuclear reactor kinetics was developed utilizing angular flux time-derivative propagation. This method avoids the requirement of storing the angular flux at previous points in time to represent a discretized time derivative; instead, an equation for the angular flux time derivative along 1D spatial characteristics is derived and solved concurrently with the 1D transport characteristic equation. This approach allows the angular flux time derivative to be recast principally in terms of the neutron source time derivatives, which are approximated to high-order accuracy using the backward differentiation formula (BDF). This approach, called Source Derivative Propagation (SDP), drastically reduces the memory requirements of time-dependent MOC relative to methods that require storing the angular flux. An SDP method was developed for 2D and 3D applications and implemented in the computer code DeCART in 2D. DeCART was used to model two reactor transient benchmarks: a modified TWIGL problem and a C5G7 transient. The SDP method accurately and efficiently replicated the solution of the conventional time-dependent MOC method using two orders of magnitude less memory.
On algebraic time-derivative estimation and deadbeat state reconstruction
DEFF Research Database (Denmark)
Reger, Johann; Jouffroy, Jerome
2009-01-01
This paper places into perspective the so-called algebraic time-derivative estimation method recently introduced by Fliess and co-authors with standard results from linear statespace theory for control systems. In particular, it is shown that the algebraic method can essentially be seen...
Maximilien Brice
2003-01-01
Each of the two coils for the LHCb magnet comprises 15 individual monolayer 'pancakes' of identical trapezoidal racetrack shape, and is bent at 45 degrees on the two transverse sides. Each pancake consists of eight turns of conductor, wound from a single length (approx. 290 m) of extruded aluminium. The coils have arrived at CERN; one of them is seen here being unloaded above the LHCb experimental cavern.
Deriving the time-independent Schrödinger equation
Gorard, Jonathan
2016-11-01
A discussion of the physical meaning of the Schrödinger wave equation can not only constitute an exciting introduction to some of the more abstract ideas of quantum mechanics, but serves more generally as a useful demonstration of the application of mathematics to modern physics. This frontline uses physical concepts and mathematical techniques that would be accessible to a sufficiently interested secondary school student, in order to derive the simplest, one-dimensional case of the time-independent Schrödinger equation: the derivation relies only upon aspects of Newtonian/wave mechanics, quantum theory, complex numbers and calculus that would be covered in an advanced secondary school syllabus.
Time-derivative preconditioning method for multicomponent flow
Housman, Jeffrey Allen
A time-derivative preconditioned system of equations suitable for the numerical simulation of single component and multicomponent inviscid flows at all speeds is formulated. The system is shown to be hyperbolic in time and remain well-posed at low Mach numbers, allowing an efficient time marching solution strategy to be utilized from transonic to incompressible flow speeds. For multicomponent flow at low speed, a preconditioned nonconservative discretization scheme is described which preserves pressure and velocity equilibrium across fluid interfaces, handles sharp liquid/gas interfaces with large density ratios, while remaining well-conditioned for time marching methods. The method is then extended to transonic and supersonic flows using a hybrid conservative/nonconservative formulation which retains the pressure/velocity equilibrium property and converges to the correct weak solution when shocks are present. In order to apply the proposed model to complex flow applications, the overset grid methodology is used where the equations are transformed to a nonorthogonal curvilinear coordinate system and discretized on structured body-fitted curvilinear grids. The multicomponent model and its extension to homogeneous multiphase mixtures is discussed and the hyperbolicity of the governing equations is demonstrated. Low Mach number perturbation analysis is then performed on the system of equations and a local time-derivative preconditioning matrix is derived allowing time marching numerical methods to remain efficient at low speeds. Next, a particular time marching numerical method is presented along with three discretization schemes for the convective terms. These include a conservative preconditioned Roe type method, a nonconservative preconditioned Split Coefficient Matrix (SCM) method, and hybrid formulation which combines the conservative and nonconservative schemes using a simple switching function. A characteristic boundary treatment which includes time-derivative
Force-Time Curve Comparison Between Weightlifting Derivatives.
Suchomel, Timothy J; Sole, Christopher J
2016-08-24
The force production characteristics of three weightlifting derivatives were examined by comparing the force-time curves of each exercise. Sixteen resistance-trained men performed repetitions of the hang power clean (HPC), jump shrug (JS), and hang high pull (HHP) on a force platform at several relative loads. Relative peak force (PFRel), relative impulse (IMPRel), peak rate of force development (PRFD), and time normalized force-time curves of each exercise were compared. The JS produced greater PFRel compared to the HPC (p force-time profiles were similar during the first 75-80% of the movement; however, the JS produced markedly different force-time characteristics in the final 20-25% of the movement. The JS produced superior force production characteristics, namely PFRel, IMPRel, and PRFD, as well as a unique force-time profile, compared to the HPC and HHP across several loads.
A time-dependent method of characteristics formulation with time derivative propagation
Hoffman, Adam J.
We developed a new time-dependent neutron transport method for nuclear reactor kinetics using method of characteristics (MOC) with angular flux time derivative propagation. In contrast to conventional time integration methods which use local finite difference approximations to treat the time derivative, the new method solves for the spatially-dependent angular flux time derivative by propagation along characteristics in space. This results in the angular flux time derivative being recast in terms of the neutron source time derivatives, and thus the new method is called Source Derivative Propagation (SDP). We developed three SDP methods using different approximations, and they require much less memory than the conventional methods. For SDP, we approximate the source derivatives using backward differences. This is analogous to the backward differentiation formula (BDF), and our results confirmed that the high-order SDP approximations reproduced the high-order angular flux derivative approximation of equivalent order BDF. We assessed SDP by comparison to conventional time-dependent MOC methods. This included both a reference method (RBDC) which stored the angular flux and a popular approximate method (IBDC). We performed error analysis for SDP, RBDC, and IBDC. This informed the refinement of the SDP methods, and clarified when SDP will be accurate. We tested SDP using the computer code DeCART, which was used to model three transients based on the TWIGL and C5G7 benchmarks. A fine time step reference solution was generated using RBDC. The SDP methods converged to the reference when the time step was refined and the BDF order increased. In addition, we observed that SDP accurately replicated the RBDC solution when the same time step and BDF order was used. This indicates that the propagated angular flux time derivative of SDP reproduced the RBDC angular flux derivative. SDP was much more accurate than the IBDC. We assessed the efficiency of SDP by comparing the run-time
Schleinitz, Katja; Petzoldt, Tibor; Krems, Josef F; Gehlert, Tina
2016-07-01
Given their potential to reach higher speed levels than conventional bicycles, the growing market share of e-bikes has been the reason for increased concerns regarding road safety. Previous studies have shown a clear relationship between object approach speed and an observers' judgment of when the object would reach a predefined position (i.e., time to arrival, TTA), with higher speed resulting in longer TTA estimates. Since TTA estimates have been linked to road users' decisions of whether or not to cross or turn in front of approaching vehicles, the higher potential speeds of e-bikes might result in an increased risk for traffic conflicts. The goal of the two experiments presented in this paper was to examine the influence of speed and a variety of other factors on TTA estimation for conventional bicycles and for e-bikes. In both experiments, participants from two age groups (20-45 years old and 65 years or older) watched video sequences of bicycles approaching at different speeds (15-25km/h) and were asked to judge the TTA at the moment the video was stopped. The results of both experiments showed that an increase in bicycle approach speed resulted in longer TTA estimates (measured as the proportion of estimated TTA relative to actual TTA) for both bicycle types (ηp(2)Exp.1=.489, ηp(2)Exp.2=.705). Compared to younger observers, older observers provided shorter estimates throughout (Exp. I: MDiff=0.35, CI [0.197, 0.509], ηp(2)=.332, Exp. II: MDiff=0.50, CI [.317, 0.682], ηp(2)=.420). In Experiment I, TTA estimates for the conventional bicycle were significantly shorter than for the e-bike (MDiff=0.03, CI [.007, 0.044], ηp(2)=.154), as were the estimates for the elder cyclist compared to the younger one (MDiff=0.05, CI [.025, 0.066], ηp(2)=.323). We hypothesized that the cause for this effect might lie in the seemingly reduced pedaling effort for the e-bike as a result of the motor assistance it provides. Experiment II was able to show that a high pedaling
公交到站时间实时预测信息发布技术研究%Bus Arrival Time Forecasting and Real-time Information Publication Technology
Institute of Scientific and Technical Information of China (English)
左忠义; 汪磊
2013-01-01
This paper proposes an effective bus arrival time forecasting algorithm based on historical records and modified by real time status. The algorithm takes into account of the offline and online prediction, which is able to reduce the complexity of calculation on server. Based on GPS real time information of bus status, the real-time bus status is obtained on the Finite state machine model on the server with the application of the Java EE, JSP, MySQL Database. A centralized, enterprise-level, mobile device oriented and request response based comprehensive system Android operating system technics is established to release the bus arrival time prediction and send the predicted information of bus status to user' s mobile device At the last section, the system is tested at No. 18 Bus line of Lushun District, Dalian, China, which demonstrates that the algorithm performs well on the system.%本文提出并采用一种离线预测与在线预测相结合的、基于历史数据并根据在线数据修正的、能减少服务器运算复杂性的较高性能的计算机模型和公交车到站时间预测算法.并以公交车实时GPS运行信息为运算依据,应用Java EE、JSP开发、MySQL数据库和Android手机操作系统开发等技术,在服务器端以公交车有限状态机模型来掌握公交车的实时信息,开发了一个集中式、企业级、手机平台上的、基于请求与响应的综合系统,能够向乘客手机客户端发送目标线路上车辆到站情况的预测信息,提高出行效率.最后基于大连市旅顺口区18路公交车运行数据进行了系统测试,结果表明,以该算法为基础的系统具有良好的性能.
基于到达时间差直方图的信号分选算法研究%A Signal Sorting Algorithm Based on Time Difference of Arrival.Histogram
Institute of Scientific and Technical Information of China (English)
杨翔; 顾洪宇
2015-01-01
The Time Difference Of Arrival (TDOA) histogram is effective for pulse train de-interleaving in radar detection. The performance of TDOA-histogram based pulse sorting algorithm depends on several parameters in the histogram, such as the Pulse Repetition Interval (PRI) detection threshold and the box length, which are set posteriorly in traditional TDOA-histogram based algorithm. In this paper, the explicit expressions of detection threshold for various PRI modes (i.e. stable, jitter, and stagger) are derived, and the relationship among these parameters are revealed. Consequently, a signal sorting algorithm is proposed, and its performance is validated by simulation in complex signal environment.%到达时间差(TDOA)直方图分析是电子支援侦察雷达信号主分选的基础；相关信号分选算法的性能与TDOA直方图脉冲重复间隔(PRI)检测门限的设定密切相关。为揭示PRI检测门限与TDOA直方图参数之间的关系，解决传统PRI检测门限依靠经验设定、无法灵活调整的问题，该文从分析TDOA直方图与脉冲序列的统计性质入手，推导了直方图稳定PRI、抖动PRI和参差PRI检测门限的解析表达式，提出了基于TDOA直方图PRI检测的信号分选算法，并通过仿真验证了算法的有效性。
Pradhan, Prabhakar; Sahay, Peeyush; Almabadi, Huda M.
2016-01-01
Considering the complex reflection amplitude R=|R|exp(i{\\theta}) of a light wave, real delay time {\\tau}_r (i.e., sojourn or Wigner delay time), which is the energy derivative of the real phase ({\\tau}_r =d{\\theta}/cdk), and complex delay time {\\tau}_i , which is the energy derivative of the reflection coefficient ({\\tau}_i=d{\\theta}_i/cdk, |R|=r^1/2=exp(-{\\theta}_i)), have the same statistical form and a mirror image with a shift in time in weak disorder and short length regime. Real delay t...
Mathieu, Julie; Bootsma, Reinoud J; Berthelon, Catherine; Montagne, Gilles
2017-02-01
Using a fixed-base driving simulator we compared the effects of the size and type of traffic vehicles (i.e., normal-sized or double-sized cars or motorcycles) approaching an intersection in two different tasks. In the perceptual judgment task, passively moving participants estimated when a traffic vehicle would reach the intersection for actual arrival times (ATs) of 1, 2, or 3s. In line with earlier findings, ATs were generally underestimated, the more so the longer the actual AT. Results revealed that vehicle size affected judgments in particular for the larger actual ATs (2 and 3s), with double-sized vehicles then being judged as arriving earlier than normal-sized vehicles. Vehicle type, on the other hand, affected judgments at the smaller actual ATs (1 and 2s), with cars then being judged as arriving earlier than motorcycles. In the behavioral task participants actively drove the simulator to cross the intersection by passing through a gap in a train of traffic. Analyses of the speed variations observed during the active intersection-crossing task revealed that the size and type of vehicles in the traffic train did not affect driving behavior in the same way as in the AT judgment task. First, effects were considerably smaller, affecting driving behavior only marginally. Second, effects were opposite to expectations based on AT judgments: driver approach speeds were smaller (rather than larger) when confronted with double-sized vehicles as compared to their normal-sized counterparts and when confronted with cars as compared to motorcycles. Finally, the temporality of the effects was different on the two tasks: vehicle size affected driver approach speed in the final stages of approach rather than early on, while vehicle type affected driver approach speed early on rather than later. Overall, we conclude that the active control of approach to the intersection is not based on successive judgments of traffic vehicle arrival times. These results thereby question the
Arrival first queueing networks with applications in kanban production systems
Boucherie, Richard J.; Chao, Xiuli; Miyazawa, Masakiyo
2003-01-01
In this paper, we introduce a new class of queueing networks called arrival first networks. We characterise its transition rates and derive the relationship between arrival rules, linear partial balance equations, and product form stationary distributions. This model is motivated by production syste
Arrival first queueing networks with applications in kanban production systems
Boucherie, R.J.; Chao, X.; Miyazawa, M.
2001-01-01
In this paper we introduce a new class of queueing networks called {\\it arrival first networks}. We characterise its transition rates and derive the relationship between arrival rules, linear partial balance equations, and product form stationary distributions. This model is motivated by production
Arrival first queueing networks with applications in kanban production systems
Boucherie, Richardus J.; Chao, X.; Miyazawa, M.
2003-01-01
In this paper, we introduce a new class of queueing networks called arrival first networks. We characterise its transition rates and derive the relationship between arrival rules, linear partial balance equations, and product form stationary distributions. This model is motivated by production
Arrival first queueing networks with applications in kanban production systems
Boucherie, Richardus J.; Chao, X.; Miyazawa, M.
2001-01-01
In this paper we introduce a new class of queueing networks called {\\it arrival first networks}. We characterise its transition rates and derive the relationship between arrival rules, linear partial balance equations, and product form stationary distributions. This model is motivated by production
Time derivatives of the spectrum: Relaxing the stationarity assumption
Prieto, G. A.; Thomson, D. J.; Vernon, F. L.
2005-12-01
Spectrum analysis of seismic waveforms has played a significant role towards the understanding of multiple aspects of Earth structure and earthquake source physics. In recent years the multitaper spectrum estimation approach (Thomson, 1982) has been applied to geophysical problems providing not only reliable estimates of the spectrum, but also estimates of spectral uncertainties (Thomson and Chave, 1991). However, these improved spectral estimates were developed under the assumption of local stationarity and provide an incomplete description of the observed process. It is obvious that due to the intrinsic attenuation of the Earth, the amplitudes, and thus the frequency contents are changing with time as waves pass through a seismic station. There have been incredible improvements in different techniques to analyze non-stationary signals, including wavelet decomposition, Wigner-Ville spectrum and the dual-frequency spectrum. We apply one of the recently developed techniques, the Quadratic Inverse Theory (Thomson, 1990, 1994), combined with the multitaper technique to look at the time derivatives of the spectrum. If the spectrum is reasonably white in a certain bandwidth, using QI theory, we can estimate the derivatives of the spectrum at each frequency. We test synthetic signals to corroborate the approach and apply it the records of small earthquakes at local distances. This is a first approach to try and combine the classical spectrum analysis without the assumption of stationarity that is generally taken.
Deriving time discounting correction factors for TTO tariffs.
Attema, Arthur E; Brouwer, Werner B F
2014-04-01
The Time Trade-off (TTO) method is a popular method for valuing health state utilities and is frequently used in economic evaluations. However, this method produces utilities that are distorted by several biases. One important bias entails the failure to incorporate time discounting. This paper aims to measure time discounting for health outcomes in a sample representative for the general population. In particular, we estimate TTO scores alongside time discounting in order to derive a set of correction factors that can be employed to correct raw TTO scores for the downward bias caused by time discounting. We find substantial positive correction factors, which are increasing with the severity of the health state. Furthermore, higher discounting is found when using more severe health states in the discounting elicitation task. More research is needed to further develop discount rate elicitation procedures and test their validity, especially in general public samples. Moreover, future research should investigate the correction of TTO values for other biases as well, such as loss aversion, and to develop a criterion to test the external validity of TTO scores.
Angle of arrival estimation using spectral interferometry
Energy Technology Data Exchange (ETDEWEB)
Barber, Z.W.; Harrington, C.; Thiel, C.W.; Babbitt, W.R. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Krishna Mohan, R., E-mail: krishna@spectrum.montana.ed [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States)
2010-09-15
We have developed a correlative signal processing concept based on a Mach-Zehnder interferometer and spatial-spectral (S2) materials that enables direct mapping of RF spectral phase as well as power spectral recording. This configuration can be used for precise frequency resolved time delay estimation between signals received by a phased antenna array system that in turn could be utilized to estimate the angle of arrival. We present an analytical theoretical model and a proof-of-principle demonstration of the concept of time difference of arrival estimation with a cryogenically cooled Tm:YAG crystal that operates on microwave signals modulated onto a stabilized optical carrier at 793 nm.
Polymer quantization, stability and higher-order time derivative terms
Cumsille, Patricio; Ossandon, Sebastian; Reyes, Camilo
2015-01-01
The stability of higher-order time derivative theories using the polymer extension of quantum mechanics is studied. First, we focus on the well-known Pais-Uhlenbeck model and by casting the theory into the sum of two decoupled harmonic oscillators we show that the energy spectrum is composed with positive and negative energy parts. The Schrodinger quantization of the model with creation and annihilations operators leads to a theory with unbounded Hamiltonian that can be interpreted in terms of normal particles and Lee-Wick-like particles responsible for the instability. We investigate whether the fundamental discreetness implicit in the polymer quantization can regularize the effects of the negative energies introduced by the Lee-Wick-like particles which are associated to a high-energy scale. Precisely, we show that the polymer quantization leads to a positive defined Hamiltonian whose stability is improved as the number of Lee-Wick-like particles grows.
Delay and Its Time-Derivative Dependent Bounded Real Lemma for Linear Time-Delay Systems
Institute of Scientific and Technical Information of China (English)
JIANGXiefu; XUWenli
2004-01-01
Based on an appropriate Lyapunov-Krasovskii functional, this paper deals with the problem of the bounded real lemma for linear continuous-time systems with state delay. The system under consideration involves state time-varying time-delay. A sufficient condition for the system to possess a H∞-norm that is less than a prescribed level, is presented in a Linear matrix inequality(LMI) form which is dependent on both the size of timedelay and the size of its time-derivative. Due to that fewercross terms should be bounded, our result is less conservative. Finally, an example is presented to demonstrate the effectiveness of our result.
Queues and risk models with simultaneous arrivals
Badila, E.S.; Boxma, O.J.; Resing, J.A.C.; Winands, E.M.M.
2014-01-01
We focus on a particular connection between queueing and risk models in a multidimensional setting. We first consider the joint workload process in a queueing model with parallel queues and simultaneous arrivals at the queues. For the case that the service times are ordered (from largest in the firs
Tourist Arrivals to Sabah by Using Fuzzy Forecasting
Directory of Open Access Journals (Sweden)
Tarmudi Zamali
2014-01-01
Full Text Available The aim of this paper is to investigate the existing tourist trend arrival in Sabah based on fuzzy approach. It focuses on the latest 12 years (2002 – 2013 visitors arrival based on their nationality for forecasting purposes. Based on Sabah Tourism Board’s data, the tourist arrival continue to grow annually but with an inconsistent number of arrival. This can be seen from the trend of tourist arrival from 2011 to 2012. There is an increase in the number of arrival but only at 1.1 % compared to the other years which are in the rank of 10 – 18% increase in number of arrival per year. Therefore, the purpose of this study is to predict the number of tourist arrival to Sabah. The study employs the modification of Fuzzy Delphi Method (FDM and utilizes the flexibility of triangular fuzzy numbers (TFNs as well as fuzzy averaging to deal with the yearly inconsistency numbers of visitor’s arrival. Then, the trio levels of alpha (α-cut was used via linguistic variables to assess the confidence of decision made and to overcome the uncertainty of the input data sets. The analysis was carried out using fully data sets obtained from the official website of Sabah tourism board. Results show that our proposed forecasting approach offers a new dimension technique as compared to the traditional statistical method. It also derived more confident decision and precision forecast for Sabah tourism authority planning purposes.
Directory of Open Access Journals (Sweden)
Rehab F. Khalaf
2011-01-01
Full Text Available We study a queuing system which is equipped with a stand-by server in addition to the main server. The stand-by server provides service to customers only during the period of absence of the main server when either the main server is on a vacation or it is in the state of repairs due to a sudden failure from time to time. The service times, vacation times, and repair times are assumed to follow general arbitrary distributions while the stand-by service times follow exponential distribution. Supplementary variables technique has been used to obtain steady state results in explicit and closed form in terms of the probability generating functions for the number of customers in the queue, the average number of customers, and the average waiting time in the queue while the MathCad software has been used to illustrate the numerical results in this work.
Forecasting tourist arrivals in South Africa
Directory of Open Access Journals (Sweden)
Andrea Saayman
2010-12-01
Full Text Available Purpose: The aim of this paper is to model and forecast tourism to South Africa from the country's main intercontinental tourism markets. These include Great Britain, Germany, the Netherlands, the United States of America and France. Problem investigated: Tourism to South Africa has grown substantially since the first democratic elections in 1994. It is currently the third largest industry in the country and a vital source of foreign exchange earnings. Tourist arrivals continue to grow annually, and have shown some resilience to a number of emerging market crises, including the terrorist attacks in the USA. Business success, marketing decisions, government's investment policy as well as macroeconomic policy are influenced by the accuracy of tourism forecasts, since the tourism product comprises a number of services that cannot be accumulated. Accurate forecasts of tourism demand are paramount to ensure the availability of such services when demanded. In addition, the seasonal nature of tourism leads to a pattern of excess capacity followed by shortage in capacity. Method: Since univariate time series modelling has proved to be a very successful method for forecasting tourist arrivals, it is also the method employed in this paper. The naïve model is tested against a standard ARIMA model, as well as the Holt-Winters exponential smoothing and seasonal-non-seasonal ARIMA models. Forecasting accuracy is assessed using the mean absolute percentage error, root mean square error and Theill's U of the various models. Monthly tourist arrivals from 1994 to 2006 are used in the analysis, and arrivals are forecasted for 2007. Findings: The results show that seasonal ARIMA models deliver the most accurate predictions of arrivals over three time horizons, namely three months, six months and 12 months. Value: This paper is the first tourist arrivals forecast using South African data for the country as a whole, and therefore it forms an interesting case study
Strategic Arrivals Recommendation Tool Project
National Aeronautics and Space Administration — During the conduct of a NASA Research Announcement (NRA) in 2012 and 2013, the Mosaic ATM team first developed the Strategic Arrivals Recommendation Tool concept, or...
Time-fractional derivatives in relaxation processes: a tutorial survey
Mainardi, Francesco
2008-01-01
The aim of this tutorial survey is to revisit the basic theory of relaxation processes governed by linear differential equations of fractional order. The fractional derivatives are intended both in the Rieamann-Liouville sense and in the Caputo sense. After giving a necessary outline of the classical theory of linear viscoelasticity, we contrast these two types of fractional derivatives in their ability to take into account initial conditions in the constitutive equations of fractional order. We also provide historical notes on the origins of the Caputo derivative and on the use of fractional calculus in viscoelasticity.
Institute of Scientific and Technical Information of China (English)
章涵; 王道洪; 吕伟涛; 孟青; 张义军
2012-01-01
Single-station-based three-dimensional lightning channel imaging system,which uses the differential time of arrival of thunder,has been developed.The system consists of a small-size microphone array,a data collection and storage system.The microphone array is consisted of four microphones which work at a frequency range from 15 to 20 kHz.Thunder signals recorded by different microphones are processed by the cross-correlation analysis to obtain the differential time of arrival at different microphones,and the direction the thunder propagation is calculated by using the least square method.The distance from the thunder source to the array is determined by the time interval between the arrival of the electromagnetic signal and the thunder.Then the three-dimensional thunder sources are obtained by combining the direction and distance of thunder.The thunder signal of a rocket-triggered lightning comparing with 8 return strokes was recorded by this system,and the lightning channel imaging results have been compared with the photographs observed by a high-speed camera.The thunder source and photograph are found to agree fairly well,which indicates that the system developed in this study is feasible and can be used as a convenient lightning channel 3D imaging tool.%利用麦克风阵列采集雷声信号,设计了一套由麦克风阵列和便携式数据采集存储设备组成的单站闪电通道三维定位系统,采用CCF相关函数法计算了雷声脉冲信号到达不同麦克风的时间差,通过最小二乘法获得声源的方向角和仰角信息,并结合声源与麦克风阵列的距离定位声源的三维位置。对一次包括8次回击的人工触发闪电过程进行了观测,得到多个声源点的三维定位信息。系统的定位结果与高速摄像的观测结果具有较好的一致性,定位方法合理、可行,为进一步研发便携式闪电通道三维定位系统奠定了基础。
Directory of Open Access Journals (Sweden)
S. M. P. McKenna-Lawlor
2012-02-01
Full Text Available The performance of the Hakamada Akasofu-Fry, version 2 (HAFv.2 numerical model, which provides predictions of solar shock arrival times at Earth, was subjected to a statistical study to investigate those solar/interplanetary circumstances under which the model performed well/poorly during key phases (rise/maximum/decay of solar cycle 23. In addition to analyzing elements of the overall data set (584 selected events associated with particular cycle phases, subsets were formed such that those events making up a particular sub-set showed common characteristics. The statistical significance of the results obtained using the various sets/subsets was generally very low and these results were not significant as compared with the hit by chance rate (50%. This implies a low level of confidence in the predictions of the model with no compelling result encouraging its use. However, the data suggested that the success rates of HAFv.2 were higher when the background solar wind speed at the time of shock initiation was relatively fast. Thus, in scenarios where the background solar wind speed is elevated and the calculated success rate significantly exceeds the rate by chance, the forecasts could provide potential value to the customer. With the composite statistics available for solar cycle 23, the calculated success rate at high solar wind speed, although clearly above 50%, was indicative rather than conclusive. The RMS error estimated for shock arrival times for every cycle phase and for the composite sample was in each case significantly better than would be expected for a random data set. Also, the parameter "Probability of Detection, yes" (PODy which presents the Proportion of Yes observations that were correctly forecast (i.e. the ratio between the shocks correctly predicted and all the shocks observed, yielded values for the rise/maximum/decay phases of the cycle and using the composite sample of 0.85, 0.64, 0.79 and 0.77, respectively. The statistical
Chalmé-Calvet, Raphaël; de Naurois, Mathieu; Tavernet, Jean-Paul
2015-01-01
In 2012, the High Energy Stereoscopic System (H.E.S.S.) was expanded by a fifth telescope (CT5). With an effective mirror diameter of 28m, CT5 is able to detect the Cherenkov light of very faint gamma-ray air showers, thereby significantly lowering the energy threshold of this telescope compared to the other four telescopes. Extracting as much information as possible from the recorded shower image is crucial for background rejection and to reach an energy threshold of a few tens of GeV. The camera of CT5 is conceived to register the time of the charge pulse maximum with respect to the beginning of the 16 ns integration window of each pixel. This information can be utilised to improve the event reconstruction. It also helps to reduce the background contamination at low energies. We present new techniques for background rejection based on CT5 timing information and evaluate their performance.
Energy Technology Data Exchange (ETDEWEB)
Rucci, A.; Vasco, D.W.; Novali, F.
2010-04-01
Deformation in the overburden proves useful in deducing spatial and temporal changes in the volume of a producing reservoir. Based upon these changes we estimate diffusive travel times associated with the transient flow due to production, and then, as the solution of a linear inverse problem, the effective permeability of the reservoir. An advantage an approach based upon travel times, as opposed to one based upon the amplitude of surface deformation, is that it is much less sensitive to the exact geomechanical properties of the reservoir and overburden. Inequalities constrain the inversion, under the assumption that the fluid production only results in pore volume decreases within the reservoir. We apply the formulation to satellite-based estimates of deformation in the material overlying a thin gas production zone at the Krechba field in Algeria. The peak displacement after three years of gas production is approximately 0.5 cm, overlying the eastern margin of the anticlinal structure defining the gas field. Using data from 15 irregularly-spaced images of range change, we calculate the diffusive travel times associated with the startup of a gas production well. The inequality constraints are incorporated into the estimates of model parameter resolution and covariance, improving the resolution by roughly 30 to 40%.
Cancellation of spurious arrivals in Green's function extraction and the generalized optical theorem
Snieder, R.; Van Wijk, K.; Haney, M.; Calvert, R.
2008-01-01
The extraction of the Green's function by cross correlation of waves recorded at two receivers nowadays finds much application. We show that for an arbitrary small scatterer, the cross terms of scattered waves give an unphysical wave with an arrival time that is independent of the source position. This constitutes an apparent inconsistency because theory predicts that such spurious arrivals do not arise, after integration over a complete source aperture. This puzzling inconsistency can be resolved for an arbitrary scatterer by integrating the contribution of all sources in the stationary phase approximation to show that the stationary phase contributions to the source integral cancel the spurious arrival by virtue of the generalized optical theorem. This work constitutes an alternative derivation of this theorem. When the source aperture is incomplete, the spurious arrival is not canceled and could be misinterpreted to be part of the Green's function. We give an example of how spurious arrivals provide information about the medium complementary to that given by the direct and scattered waves; the spurious waves can thus potentially be used to better constrain the medium. ?? 2008 The American Physical Society.
Directory of Open Access Journals (Sweden)
José Miguel Gil-García
2017-09-01
Full Text Available Safety and performance of the turbo-engine in an aircraft is directly affected by the health of its blades. In recent years, several improvements to the sensors have taken place to monitor the blades in a non-intrusive way. The parameters that are usually measured are the distance between the blade tip and the casing, and the passing time at a given point. Simultaneously, several techniques have been developed that allow for the inference—from those parameters and under certain conditions—of the amplitude and frequency of the blade vibration. These measurements are carried out on engines set on a rig, before being installed in an airplane. In order to incorporate these methods during the regular operation of the engine, signal processing that allows for the monitoring of those parameters at all times should be developed. This article introduces an architecture, based on a trifurcated optic sensor and a hardware processor, that fulfills this need. The proposed architecture is scalable and allows several sensors to be simultaneously monitored at different points around a bladed disk. Furthermore, the results obtained by the electronic system will be compared with the results obtained by the validation of the optic sensor.
A Derivation of a Microscopic Entropy and Time Irreversibility From the Discreteness of Time
Directory of Open Access Journals (Sweden)
Roland Riek
2014-06-01
Full Text Available The basic microsopic physical laws are time reversible. In contrast, the second law of thermodynamics, which is a macroscopic physical representation of the world, is able to describe irreversible processes in an isolated system through the change of entropy ΔS > 0. It is the attempt of the present manuscript to bridge the microscopic physical world with its macrosocpic one with an alternative approach than the statistical mechanics theory of Gibbs and Boltzmann. It is proposed that time is discrete with constant step size. Its consequence is the presence of time irreversibility at the microscopic level if the present force is of complex nature (F(r ≠ const. In order to compare this discrete time irreversible mechamics (for simplicity a “classical”, single particle in a one dimensional space is selected with its classical Newton analog, time reversibility is reintroduced by scaling the time steps for any given time step n by the variable sn leading to the Nosé-Hoover Lagrangian. The corresponding Nos´e-Hoover Hamiltonian comprises a term Ndf kB T ln sn (kB the Boltzmann constant, T the temperature, and Ndf the number of degrees of freedom which is defined as the microscopic entropy Sn at time point n multiplied by T. Upon ensemble averaging this microscopic entropy Sn in equilibrium for a system which does not have fast changing forces approximates its macroscopic counterpart known from thermodynamics. The presented derivation with the resulting analogy between the ensemble averaged microscopic entropy and its thermodynamic analog suggests that the original description of the entropy by Boltzmann and Gibbs is just an ensemble averaging of the time scaling variable sn which is in equilibrium close to 1, but that the entropy
Energy Technology Data Exchange (ETDEWEB)
Imam, Neena [ORNL; Barhen, Jacob [ORNL
2009-01-01
For real-time acoustic source localization applications, one of the primary challenges is the considerable growth in computational complexity associated with the emergence of ever larger, active or passive, distributed sensor networks. These sensors rely heavily on battery-operated system components to achieve highly functional automation in signal and information processing. In order to keep communication requirements minimal, it is desirable to perform as much processing on the receiver platforms as possible. However, the complexity of the calculations needed to achieve accurate source localization increases dramatically with the size of sensor arrays, resulting in substantial growth of computational requirements that cannot be readily met with standard hardware. One option to meet this challenge builds upon the emergence of digital optical-core devices. The objective of this work was to explore the implementation of key building block algorithms used in underwater source localization on the optical-core digital processing platform recently introduced by Lenslet Inc. This demonstration of considerably faster signal processing capability should be of substantial significance to the design and innovation of future generations of distributed sensor networks.
Directory of Open Access Journals (Sweden)
E. Bernal
2002-10-01
Full Text Available Las personas que ocupan una lista de espera sufren a menudo un riesgo adicional derivado del tiempo que pasa hasta que obtienen tratamiento; sin embargo, en otras ocasiones, las personas en lista no tienen necesidad del tratamiento por el que esperan. Ambos argumentos, contrastables con evidencias empíricas, serían suficientes para afirmar que debe llegar la gestión a las listas de espera dejando a un lado políticas más o menos oportunistas. Por políticas oportunistas se entiende mantener la mala información sobre listas o su "maquillaje", utilizar programas de autoconcertación sin más horizonte que llegar a final de año sin lista de más de seis meses, etcétera. El panorama no es del todo oscuro. Algunas iniciativas de gestión (incluso de Política con mayúscula se van abriendo paso y pueden entrar en la agenda de los próximos años. Así, cabe destacar la aplicación de tiempos de atención garantizada o la priorización de las listas en función de criterios explícitos. En todo caso, conviene recordar que, con la excepción de las colas producidas en las salas de espera de los centros de salud y aquéllas que se producen en las puertas de urgencias, el resto de colas del sistema están mediadas por la decisión de un médico. Así que una estrategia ineludible para gestionar las listas de espera consiste en atenuar los problemas derivados de la incertidumbre (o ignorancia con respecto al diagnóstico o al pronóstico de los pacientes.Individuals on the waiting list frequently suffer an additional risk caused by the mean time until they receive treatment; however, other individuals do not need the treatment for which they are waiting. Both arguments, which can be contrasted with empirical evidence, would be sufficient to affirm that waiting list management should be implemented, leaving aside policies that are more of less opportunistic. Opportunistic policies are understood as those providing misinformation on waiting lists or
Institute of Scientific and Technical Information of China (English)
周鹏飞; 李丕安
2013-01-01
Slot allocation of export containers in a container terminal yard has great effect on the reshuffle ratio and vessel handling efficiency. In order to make reasonable slot allocation, by considering the stochastic characteristic of container arrival and leaving time, a two-level dynamic stochastic programming model is developed. By this model, the objectives are to minimize the reshuffles when loading a ship and the storage cranes' travel distance when fetching containers. Then, after analyzing the characteristics of the problem, a heuristic algorithm is presented to solve the problem by designing priority rules for bay and stack selection. Numerical experiment results show that, with the information about container arrival or leaving, the proposed method can improve container storage slot allocation.%集装箱码头堆场出口箱箱位分配是翻箱率和装船效率的关键.为合理分配堆场出口箱箱位,考虑集装箱进出场时间的随机不确定性,建立了出口箱位随机双层规划模型,分别优化堆场预期翻箱量和龙门吊取箱时的行车成本.根据双层规划模型分别优选堆场贝和栈的特点及较优解特征,设计了求解模型的启发式算法.实验结果表明,上述方法能有效地利用集装箱不确定进出场信息改善堆场箱位分配的合理性,提高作业效率.
Reading the Arrivals of Harpalus
Directory of Open Access Journals (Sweden)
Alex Gottesman
2015-02-01
Full Text Available Harpalus’ two arrivals in Athens, first with armed force and then as a suppliant, were both intended to provoke war between Athens and Alexander, the first through fear, the second through appeal to Athenian traditions of protecting suppliants.
Deriving dynamic marketing effectiveness from econometric time series models
C. Horváth (Csilla); Ph.H.B.F. Franses (Philip Hans)
2003-01-01
textabstractTo understand the relevance of marketing efforts, it has become standard practice to estimate the long-run and short-run effects of the marketing-mix, using, say, weekly scanner data. A common vehicle for this purpose is an econometric time series model. Issues that are addressed in the
Institute of Scientific and Technical Information of China (English)
孙微; 李世勇; 田乃硕
2007-01-01
In this paper, we discuss the queue Mξ/G/1 with different arrival rates on the multiple adaptive vacations and setup times. We derive the probability generating function (p.g.f.)of the steady-state queue length by the method of embedded Markov chain and the Laplace-Stieltjes transform (LST)of the steady-state waiting time (FCFS). From the results, we obtain the conclusion that the steady-state queue length and waiting time have the property of stochastic decomposition. And we also get the LST of busy period and give several special cases. Many discussed models as to Mξ/G/1 are special cases of the model.%本文研究具有不同到达率的带有启动时间的多级适应性休假Mξ/G/1排队模型,应用嵌入马尔可夫链方法推导出了稳态队长和等待时间(先到先服务规则)分布,并验证了稳态队长和稳态等待时间具有随机分解性,而且给出了忙期分布.许多关于Mξ/G/1的排队模型都可以看作是此模型的特例.
Isoperimetric problems on time scales with nabla derivatives
Almeida, Ricardo; Torres, Delfim F. M.
2008-01-01
We prove a necessary optimality condition for isoperimetric problems under nabla-differentiable curves. As a consequence, the recent results of [M.R. Caputo, A unified view of ostensibly disparate isoperimetric variational problems, Appl. Math. Lett. (2008), doi:10.1016/j.aml.2008.04.004], that put together seemingly dissimilar optimal control problems in economics and physics, are extended to a generic time scale. We end with an illustrative example of application of our main result to a dyn...
Queues with Dropping Functions and General Arrival Processes.
Chydzinski, Andrzej; Mrozowski, Pawel
2016-01-01
In a queueing system with the dropping function the arriving customer can be denied service (dropped) with the probability that is a function of the queue length at the time of arrival of this customer. The potential applicability of such mechanism is very wide due to the fact that by choosing the shape of this function one can easily manipulate several performance characteristics of the queueing system. In this paper we carry out analysis of the queueing system with the dropping function and a very general model of arrival process--the model which includes batch arrivals and the interarrival time autocorrelation, and allows for fitting the actual shape of the interarrival time distribution and its moments. For such a system we obtain formulas for the distribution of the queue length and the overall customer loss ratio. The analytical results are accompanied with numerical examples computed for several dropping functions.
Pricing multi-asset financial derivatives with time-dependent parameters—Lie algebraic approach
Directory of Open Access Journals (Sweden)
C. F. Lo
2002-01-01
Full Text Available We present a Lie algebraic technique for the valuation of multi-asset financial derivatives with time-dependent parameters. Exploiting the dynamical symmetry of the pricing partial differential equations of the financial derivatives, the new method enables us to derive analytical closed-form pricing formulae very straightforwardly. We believe that this new approach will provide an efficient and easy-to-use method for the valuation of financial derivatives.
Drought in Africa caused delayed arrival of European songbirds.
Tøttrup, A P; Klaassen, R H G; Kristensen, M W; Strandberg, R; Vardanis, Y; Lindström, Å; Rahbek, C; Alerstam, T; Thorup, K
2012-12-01
Despite an overall advancement in breeding area arrival, one of the latest spring arrivals in northwest Europe since 1950 of several trans-Saharan songbird species occurred in 2011. Year-round tracking of red-backed shrikes and thrush nightingales revealed that the cause of the delay was a prolongation of stopover time during spring migration at the Horn of Africa, which was affected by extreme drought. Our results help to establish a direct link at the individual level between changes in local climate during migration and arrival and breeding condition in Europe thousands of kilometers further north.
A discrete single server queue with Markovian arrivals and phase type group services
Directory of Open Access Journals (Sweden)
Attahiru Sule Alfa
1995-01-01
Full Text Available We consider a single-server discrete queueing system in which arrivals occur according to a Markovian arrival process. Service is provided in groups of size no more than M customers. The service times are assumed to follow a discrete phase type distribution, whose representation may depend on the group size. Under a probabilistic service rule, which depends on the number of customers waiting in the queue, this system is studied as a Markov process. This type of queueing system is encountered in the operations of an automatic storage retrieval system. The steady-state probability vector is shown to be of (modified matrix-geometric type. Efficient algorithmic procedures for the computation of the rate matrix, steady-state probability vector, and some important system performance measures are developed. The steady-state waiting time distribution is derived explicitly. Some numerical examples are presented.
Healthcare system information at language schools for newly arrived immigrants
DEFF Research Database (Denmark)
Tynell, Lena Lyngholt; Wimmelmann, Camilla Lawaetz; Jervelund, Signe Smith
2017-01-01
Objective: In most European countries, immigrants do not systematically learn about the host countries’ healthcare system when arriving. This study investigated how newly arrived immigrants perceived the information they received about the Danish healthcare system. Method: Immigrants attending...... a language school in Copenhagen in 2012 received either a course or written information on the Danish healthcare system and subsequently evaluated this quantitatively. Results: The evaluation revealed a positive appraisal of the course/information provided. Conclusion: In times of austerity, incorporating...
Ryabinkin, Ilya G; Nagesh, Jayashree; Izmaylov, Artur F
2015-11-05
We have developed a numerical differentiation scheme that eliminates evaluation of overlap determinants in calculating the time-derivative nonadiabatic couplings (TDNACs). Evaluation of these determinants was the bottleneck in previous implementations of mixed quantum-classical methods using numerical differentiation of electronic wave functions in the Slater determinant representation. The central idea of our approach is, first, to reduce the analytic time derivatives of Slater determinants to time derivatives of molecular orbitals and then to apply a finite-difference formula. Benchmark calculations prove the efficiency of the proposed scheme showing impressive several-order-of-magnitude speedups of the TDNAC calculation step for midsize molecules.
HETEROGENEOUS INFORMATION ARRIVAL AND R&D OPTION PRICING
Institute of Scientific and Technical Information of China (English)
薛明皋; 李楚霖
2003-01-01
The paper models the arrival of heterogeneous information during R&D stagesas a doubly stochastic Poisson process(DSPP). The new product market introduction isthought of as option on an option(a compound option). This paper derives an analyticapproximation valuation formula for the R&D option, and demonstrates that the accountsfor heterogeneous information arrival may reduce the pricing biases. This way, the gapbetween real option theory and the practice of decision making with respect to investmentin R&D is diminished.
Institute of Scientific and Technical Information of China (English)
Zhang Min-Min; Wang Can-Jun; Mei Dong-Cheng
2011-01-01
The effects of the time delay on the upper bound of the time derivative of information entropy are investigated in a time-delayed dynamical system driven by correlated noise.Using the Markov approximation of the stochastic delay differential equations and the Schwartz inequality principle,we obtain an analytical expression for the upper bound UB(t) of the time derivative of the information entropy.The results show that there is a critical value of T (delay time),and UB(t) presents opposite behaviours on difference sides of the critical value.For the case of the weak additive noise,T can induce a reentrance transition.Delay time T also causes a reversal behaviour in UB(t)-λ plot,where λ denotes the decree of the correlation between the two noises.
Method reduces computer time for smoothing functions and derivatives through ninth order polynomials
Glauz, R. D.; Wilgus, C. A.
1969-01-01
Analysis presented is an efficient technique to adjust previously calculated orthogonal polynomial coefficients for an odd number of equally spaced data points. The adjusting technique derivation is for a ninth order polynomial. It reduces computer time for smoothing functions.
Directory of Open Access Journals (Sweden)
Andreea Sterian
2010-01-01
accuracy some significant quantities corresponding to the dynamic system. For fast phenomena, such significant quantities are represented by the derivatives of the received signals. In case of advanced computer modeling, the received signal should be filtered and converted into a time series corresponding to the estimated values for the dynamic system through a sampling procedure. This paper will show that present-day methods for computing in a robust manner the first derivative of a received signal (using an oscillating system working on a limited time interval and a supplementary differentiation method can be extended to the robust computation of higher order derivatives of the received signal by using a specific set of second-order oscillating systems (working also on limited time intervals so as estimative values for higher-order derivatives are to be directly generated (avoiding the necessity of additional differentiation or amplifying procedures, which represent a source of supplementary errors in present-day methods.
Institute of Scientific and Technical Information of China (English)
谢胜东; 胡爱群; 黄毅; 姜禹
2013-01-01
为了提高单目标定位的精度，以到达时间差为物理量，提出了一种两步最小二乘定位算法（TSLS）．TSLS 首先基于普通线性最小二乘估计模型，采用线性纠正最小二乘定位算法（LCLS）获得目标节点位置的估计值；然后计算出目标节点到达不同基站的距离差，并用该距离差来近似实际距离差；最后基于约束总体最小二乘估计模型，利用约束总体最小二乘定位算法（CTLS）对目标节点位置进行二次估计．由于 TSLS 本质上是通过减少 CTLS 的矩阵误差来提高 CTLS 的性能，因此可以看成是一种增强型 CTLS 算法．仿真分析表明，TSLS 算法的总体性能要优于 CTLS算法和 LCLS 算法．%In order to improve the localization precision for a single object,a two-step least square localization algorithm (TSLS)is proposed based on the time difference of arrival.The object loca-tion is first estimated by the line correct least square algorithm (LCLS)based on the common least square estimation model.Then the distance difference from the object to different base stations is computed based on the estimated location.Finally,the location is estimated by the constrained total least square algorithm (CTLS)based on the constrained total least square model,in which the dis-tance difference is approximated not by the measurement but by the calculation.Essentially,TSLS improves the performance of CTLS by reducing the errors in the matrix of CTLS,so it can be seen as an enhanced CTLS algorithm.Simulation results show that the performance of the TSLS is better than that of the CTLS and LCLS.
A derivation of a microscopic entropy and time irreversibility from the discreteness of time
Riek, Roland
2014-01-01
All of the basic microsopic physical laws are time reversible. In contrast, the second law of thermodynamics, which is a macroscopic physical representation of the world, is able to describe irreversible processes in an isolated system through the change of entropy S larger than 0. It is the attempt of the present manuscript to bridge the microscopic physical world with its macrosocpic one with an alternative approach than the statistical mechanics theory of Gibbs and Boltzmann. It is proposed that time is discrete with constant step size. Its consequence is the presence of time irreversibility at the microscopic level if the present force is of complex nature (i.e. not const). In order to compare this discrete time irreversible mechamics (for simplicity a classical, single particle in a one dimensional space is selected) with its classical Newton analog, time reversibility is reintroduced by scaling the time steps for any given time step n by the variable sn leading to the Nose-Hoover Lagrangian. The corresp...
Saxena, R. K.; Mathai, A. M.; Haubold, H. J.
2015-10-01
This paper deals with the investigation of the computational solutions of an unified fractional reaction-diffusion equation, which is obtained from the standard diffusion equation by replacing the time derivative of first order by the generalized fractional time-derivative defined by Hilfer (2000), the space derivative of second order by the Riesz-Feller fractional derivative and adding the function ϕ (x, t) which is a nonlinear function governing reaction. The solution is derived by the application of the Laplace and Fourier transforms in a compact and closed form in terms of the H-function. The main result obtained in this paper provides an elegant extension of the fundamental solution for the space-time fractional diffusion equation obtained earlier by Mainardi et al. (2001, 2005) and a result very recently given by Tomovski et al. (2011). Computational representation of the fundamental solution is also obtained explicitly. Fractional order moments of the distribution are deduced. At the end, mild extensions of the derived results associated with a finite number of Riesz-Feller space fractional derivatives are also discussed.
Liquid Argon Barrel Cryostat Arrived
Pailler, P
Last week the first of three cryostats for the ATLAS liquid argon calorimeter arrived at CERN. It had travelled for 46 days over several thousand kilometers from Japan to CERN. During three years it has been fabricated by Kawasaki Heavy Industries Ltd. at Harima, close to Kobe, under contract from Brookhaven National Laboratory (BNL) of the U.S.. This cryostat consists of two concentric cylinders made of aluminium: the outer vacuum vessel with a diameter of 5.5 m and a length of 7 m, and the inner cold vessel which will contain the electromagnetic barrel calorimeter immersed in liquid argon. The total weight will be 270 tons including the detectors and the liquid argon. The cryostat is now located in building 180 where it will be equipped with 64 feed-throughs which serve for the passage of 122,880 electrical lines which will carry the signals of the calorimeter. After integration of the calorimeter, the solenoidal magnet of ATLAS will be integrated in the vacuum vessel. A final cold test of the cryostat inc...
Analytical Solutions of the Space-Time Fractional Derivative of Advection Dispersion Equation
Directory of Open Access Journals (Sweden)
Abdon Atangana
2013-01-01
Full Text Available Fractional advection-dispersion equations are used in groundwater hydrology to model the transport of passive tracers carried by fluid flow in porous medium. A space-time fractional advection-dispersion equation (FADE is a generalization of the classical ADE in which the first-order space derivative is replaced with Caputo or Riemann-Liouville derivative of order , and the second-order space derivative is replaced with the Caputo or the Riemann-Liouville fractional derivative of order . We derive the solution of the new equation in terms of Mittag-Leffler functions using Laplace transfrom. Some examples are given. The results from comparison let no doubt that the FADE is better in prediction than ADE.
Groundwater similarity across a watershed derived from time-warped and flow-corrected time series
Rinderer, M.; McGlynn, B. L.; van Meerveld, H. J.
2017-05-01
Information about catchment-scale groundwater dynamics is necessary to understand how catchments store and release water and why water quantity and quality varies in streams. However, groundwater level monitoring is often restricted to a limited number of sites. Knowledge of the factors that determine similarity between monitoring sites can be used to predict catchment-scale groundwater storage and connectivity of different runoff source areas. We used distance-based and correlation-based similarity measures to quantify the spatial and temporal differences in shallow groundwater similarity for 51 monitoring sites in a Swiss prealpine catchment. The 41 months long time series were preprocessed using Dynamic Time-Warping and a Flow-corrected Time Transformation to account for small timing differences and bias toward low-flow periods. The mean distance-based groundwater similarity was correlated to topographic indices, such as upslope contributing area, topographic wetness index, and local slope. Correlation-based similarity was less related to landscape position but instead revealed differences between seasons. Analysis of variance and partial Mantel tests showed that landscape position, represented by the topographic wetness index, explained 52% of the variability in mean distance-based groundwater similarity, while spatial distance, represented by the Euclidean distance, explained only 5%. The variability in distance-based similarity and correlation-based similarity between groundwater and streamflow time series was significantly larger for midslope locations than for other landscape positions. This suggests that groundwater dynamics at these midslope sites, which are important to understand runoff source areas and hydrological connectivity at the catchment scale, are most difficult to predict.
The time derivative of the kilohertz quasi-periodic oscillations in 4U 1636-53
Sanna, Andrea; Belloni, Tomaso; Altamirano, Diego
2012-01-01
We analysed all archival RXTE observations of the neutron-star low-mass X-ray binary 4U 1636-53 up to May 2010. In 528 out of 1280 observations we detected kilohertz quasi-periodic oscillations (kHz QPOs), with ~ 65% of these detections corresponding to the so-called lower kHz QPO. Using this QPO we measured, for the first time, the rate at which the QPO frequency changes as a function of QPO frequency. For this we used the spread of the QPO frequency over groups of 10 consecutive measurements, sampling timescales between 320 and 1600 s, and the time derivative of the QPO frequency over timescales of 32 to 160 s. We found that: (i) Both the QPO-frequency spread and the QPO time derivative decrease by a factor ~ 3 as the QPO frequency increases. (ii) The average value of the QPO time derivative decreases by a factor of ~ 2 as the timescale over which the derivative is measured increases from less than 64 s to 160 s. (iii) The relation between the absolute value of the QPO time derivative and the QPO frequency ...
The supermarket model with arrival rate tending to one
Brightwell, Graham
2012-01-01
In the supermarket model, there are $n$ queues, each with a single server. Customers arrive in a Poisson process with arrival rate $\\lambda n$, where $\\lambda = \\lambda (n) \\in (0,1)$. Upon arrival, a customer selects $d=d(n)$ servers uniformly at random, and joins the queue of a least-loaded server amongst those chosen. Service times are independent exponentially distributed random variables with mean~1. In this paper, we analyse the behaviour of the supermarket model in a regime where $\\lambda(n)$ tends to~1, and $d(n)$ tends to infinity, as $n \\to \\infty$. For suitable triples $(n,d,\\lambda)$, we identify a subset ${\\cal N}$ of the state space where the process remains for a long time in equilibrium. We further show that the process is rapidly mixing when started in ${\\cal N}$, and give bounds on the speed of mixing for more general initial conditions.
Space-time fractional diffusion equation using a derivative with nonsingular and regular kernel
Gómez-Aguilar, J. F.
2017-01-01
In this paper, using the fractional operators with Mittag-Leffler kernel in Caputo and Riemann-Liouville sense the space-time fractional diffusion equation is modified, the fractional equation will be examined separately; with fractional spatial derivative and fractional temporal derivative. For the study cases, the order considered is 0 < β , γ ≤ 1 respectively. In this alternative representation we introduce the appropriate fractional dimensional parameters which characterize consistently the existence of the fractional space-time derivatives into the fractional diffusion equation, these parameters related to equation results in a fractal space-time geometry provide a new family of solutions for the diffusive processes. The proposed mathematical representation can be useful to understand electrochemical phenomena, propagation of energy in dissipative systems, viscoelastic materials, material heterogeneities and media with different scales.
Directory of Open Access Journals (Sweden)
Alessandra Soler Bastos
2012-09-01
Full Text Available OBJETIVO: Caracterizar o perfil das pessoas com infarto agudo do miocárdio (IAM atendidas em um serviço de emergência e verificar o tempo de chegada (delta T. Identificar como o paciente foi transportado e correlacionar o delta T com o tratamento e prognóstico do mesmo. MÉTODOS: Pesquisa transversal, incluindo 52 pacientes admitidos na Unidade de Emergência de um Hospital de Ensino com diagnóstico de IAM, no período de julho a dezembro de 2010. A coleta de dados foi realizada por meio do prontuário e entrevista. RESULTADOS: A maioria dos pacientes era do gênero masculino, com idade média de 62,35 ± 14,66 anos, casada, poucos anos de estudo, histórico familiar de doença cardíaca, hipertensão arterial, dislipidemia e sedentarismo. Os sintomas apresentados foram dor no tórax, região epigástrica ou desconforto torácico associado à dispneia e/ou sudorese súbita. A maioria dos pacientes foi transportada por ambulância e submetida a cateterismo cardíaco, seguido de angioplastia. O delta T encontrado foi 9h54min ± 18h9min. A letalidade global do estudo foi de 3,85%. CONCLUSÃO: O reconhecimento dos sinais e sintomas do IAM pelo paciente foi fator determinante para a procura de atendimento especializado e aqueles com menor delta T apresentaram melhor prognóstico.OBJECTIVES: To characterize the profile of patients with acute myocardial infarction (AMI treated at the emergency department and to verify the time of arrival of each patient (ΔT. Identify how the patient was transported and to correlate Delta-T (ΔT with the treatment and the prognosis of each patient. METHODS: Cross-sectional survey involving 52 patients with AMI admitted to the Emergency Department of a Teaching Hospital took part in the study from July to December 2010. Data collection was performed using medical records and interviews. RESULTS: The majority of the patients were male with a mean age of 62.35 ± 14.66 years. The participants were married, with low
8 CFR 232.3 - Arriving aliens.
2010-01-01
... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Arriving aliens. 232.3 Section 232.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS DETENTION OF ALIENS FOR PHYSICAL AND MENTAL EXAMINATION § 232.3 Arriving aliens. When a district director has reasonable grounds...
Fluctuations in airport arrival and departure traffic: A network analysis
Institute of Scientific and Technical Information of China (English)
Li Shan-Mei; Xu Xiao-Hao; Meng Ling-Hang
2012-01-01
Air traffic is a typical complex system,in which movements of traffic components (pilots,controllers,equipment,and environment),especially airport arrival and departure traffic,form complicated spatial and temporal dynamics.The fluctuations of airport arrival and departure traffic are studied from the point of view of networks as the special correlation between different airports.Our collected flow volume data on the time-dependent activity of US airport arrival and departure traffic indicate that the coupling between the average flux and the fluctuation of an individual airport obeys a certain scaling law with a wide variety of scaling exponents between 1/2 and 1.These scaling phenomena can explain the interaction between the airport internal dynamics (e.g.queuing at airports,a ground delay program and following flying traffic) and a change in the external (network-wide) traffic demand (e.g.an increase in traffic during peak hours every day),allowing us to further understand the mechanisms governing the collective behaviour of the transportation system.We separate internal dynamics from external fluctuations using a scaling law which is helpful for us to systematically determine the origin of fluctuations in airport arrival and departure traffic,uncovering the collective dynamics.Hot spot features are observed in airport traffic data as the dynamical inhomogeneity in the fluxes of individual airports.The intrinsic characteristics of airport arrival and departure traffic under severe weather is discussed as well.
Age at Arrival and Life Chances Among Childhood Immigrants.
Hermansen, Are Skeie
2017-02-01
This study examines the causal relationship between childhood immigrants' age at arrival and their life chances as adults. I analyze panel data on siblings from Norwegian administrative registries, which enables me to disentangle the effect of age at arrival on adult socioeconomic outcomes from all fixed family-level conditions and endowments shared by siblings. Results from sibling fixed-effects models reveal a progressively stronger adverse influence of immigration at later stages of childhood on completed education, employment, adult earnings, occupational attainment, and social welfare assistance. The persistence of these relationships within families indicates that experiences related to the timing of childhood immigration have causal effects on later-life outcomes. These age-at-arrival effects are considerably stronger among children who arrive from geographically distant and economically less-developed origin regions than among children originating from developed countries. The age-at-arrival effects vary less by parental education and child gender. On the whole, the findings indicate that childhood immigration after an early-life formative period tends to constrain later human capital formation and economic opportunities over the life course.
Determining surface wave arrival angle anomalies
Larson, Erik W. F.; Ekström, Göran
2002-06-01
A new method for measuring arrival angles of teleseismic Love and Rayleigh waves is developed. The new method utilizes estimates of surface wave dispersion to create a phase-matched filter to isolate the Love or Rayleigh wave in three-component recordings. The polarization of the filtered wave group is determined in the time domain by application of a variation of the complex polarization method of Vidale [1986]. Orientation, linearity, and ellipticity of particle motion are estimated in several frequency bands to determine the frequency-dependent polarization. The method employs an iterative scheme, by which a predicted Love wave, based on the estimated dispersion and polarization, is subtracted from the three-component data prior to the estimation of Rayleigh wave polarization, and vice versa. The method is applied to an extensive set of Global Seismographic Network data covering the years 1989-1998. Between 4244 and 15,075 measurements are collected for fundamental mode Love and Rayleigh waves at nine different periods (37 to 150 s). Measurement uncertainties are estimated using the statistics of observations for pairwise similar paths and are generally of the order of 15-50% of the total signal, depending on the period and the wave type. Large and azimuthally invariant angle anomalies are documented for several stations and are consistent with misorientation of the horizontal seismometers. Two schemes are employed to determine the misorientations: (1) an azimuthally weighted average at each station, and (2) a joint inversion for seismometer misorientation and globally heterogeneous phase velocities. The determined corrections are robust and correlate well with those reported in earlier studies. Azimuthally varying arrival angle anomalies are shown to agree qualitatively with predictions of wave refraction calculated for recent phase velocity maps, which explain up to 30% of the variance in the new measurements.
SCHEDULING WITH REJECTION AND NON-IDENTICAL JOB ARRIVALS
Institute of Scientific and Technical Information of China (English)
Zhigang CAO; Yuzhong ZHANG
2007-01-01
In this paper, we address the scheduling problem with rejection and non-identical job arrivals, in which we may choose not to process certain jobs and each rejected job incurs a penalty.Our goal is to minimize the sum of the total penalties of the rejected jobs and the maximum completion time of the processed ones. For the off-line variant, we prove its NP-hardness and present a PTAS, and for the on-line special case with two job arrivals, we design a best possible algorithm with competitive ratio (√5+1)/2.
Tsunami Arrival Detection with High Frequency (HF Radar
Directory of Open Access Journals (Sweden)
Donald Barrick
2012-05-01
Full Text Available Quantitative real-time observations of a tsunami have been limited to deep-water, pressure-sensor observations of changes in the sea surface elevation and observations of sea level fluctuations at the coast, which are essentially point measurements. Constrained by these data, models have been used for predictions and warning of the arrival of a tsunami, but to date no system exists for local detection of an actual incoming wave with a significant warning capability. Networks of coastal high frequency (HF-radars are now routinely observing surface currents in many countries. We report here on an empirical method for the detection of the initial arrival of a tsunami, and demonstrate its use with results from data measured by fourteen HF radar sites in Japan and USA following the magnitude 9.0 earthquake off Sendai, Japan, on 11 March 2011. The distance offshore at which the tsunami can be detected, and hence the warning time provided, depends on the bathymetry: the wider the shallow continental shelf, the greater this time. We compare arrival times at the radars with those measured by neighboring tide gauges. Arrival times measured by the radars preceded those at neighboring tide gauges by an average of 19 min (Japan and 15 min (USA The initial water-height increase due to the tsunami as measured by the tide gauges was moderate, ranging from 0.3 to 2 m. Thus it appears possible to detect even moderate tsunamis using this method. Larger tsunamis could obviously be detected further from the coast. We find that tsunami arrival within the radar coverage area can be announced 8 min (i.e., twice the radar spectral time resolution after its first appearance. This can provide advance warning of the tsunami approach to the coastline locations.
Dependence of time derivative of horizontal geomagnetic field on sunspot number and aa index
National Research Council Canada - National Science Library
Falayi, Elijah O; Rabiu, Babatunde A
2013-01-01
This work investigated an interrelationship between the monthly means of time derivatives of horizontal geomagnetic field, dH/dt, sunspot number, R z , and aa index for the period of substorms (from −90 to −1800 nT...
Detection of shrimp-derived components in food by real-time fluorescent PCR.
Cao, Jijuan; Yu, Bing; Ma, Lidan; Zheng, Qiuyue; Zhao, Xin; Xu, Junyi
2011-10-01
Crustaceans such as shrimp and crabs and their products are important allergens in food, and allergic reactions due to the consumption of shrimp and crabs are frequently reported. However, the chemical properties of shrimp-derived allergens, except for Pen a I, are still unclear. Therefore, it is important to establish a more sensitive and specific method for detecting the composition of foods containing shrimp. In the present study, we developed a real-time fluorescent PCR to identify the specific shrimp-derived components in food. The primers and TaqMan probes for real-time fluorescent PCR were designed based on 16S rRNA genes through comparing a large number of nucleic acid sequences from different species of shrimp that have been published by the National Center for Biotechnology Information. In total, 56 kinds of samples, including different kinds of shrimp, crab, fish, shellfish, and octopus, were subjected to detection by real-time PCR. The results indicated that real-time fluorescent PCR could successfully identify the shrimp-derived components. In order to explore the effect of food processing on detection sensitivity, fish powder containing shrimp powder was treated by heating at 133°C for 30 min. The limit of detection of shrimp-derived components in fish powder was 0.05% (wt/wt).
DIRECTIONAL DERIVATIVE OF VECTOR FIELD AND REGULAR CURVES ON TIME SCALES
Institute of Scientific and Technical Information of China (English)
Emin (O)zyilmaz
2006-01-01
The general idea in this paper is to study curves of the parametric equations where the parameter varies in a so-called time scale, which may be an arbitrary closed subset of the set of all real numbers. We introduce the directional derivative according to the vector fields.
Does the generalized second law hold in the form of time derivative expression?
Shimomura, T; Mishima, T; Ishihara, H
2000-01-01
We investigate whether the generalized second law is valid, using two dimensional black hole spacetime, irrespective of models. A time derivative form of the generalized second law is formulated and it is shown that the law might become invalid. The way to resolve this difficulty is also presented and discussed.
Tenreiro Machado, J. A.; Galhano, Alexandra M.; Oliveira, Anabela M.; Tar, József K.
2010-03-01
This study addresses the optimization of rational fraction approximations for the discrete-time calculation of fractional derivatives. The article starts by analyzing the standard techniques based on Taylor series and Padé expansions. In a second phase the paper re-evaluates the problem in an optimization perspective by tacking advantage of the flexibility of the genetic algorithms.
A Simple Derivation of Time Dilation and Length Contraction in Special Relativity
Behroozi, Fred
2014-01-01
Undergraduate physics majors typically begin their study of modern physics with special relativity. It is here that physics students first encounter the counterintuitive concepts of time dilation and length contraction. Unfortunately, the derivations of these results are often cloaked in several layers of analysis that render them rather…
A Simple Derivation of Time Dilation and Length Contraction in Special Relativity
Behroozi, Fred
2014-01-01
Undergraduate physics majors typically begin their study of modern physics with special relativity. It is here that physics students first encounter the counterintuitive concepts of time dilation and length contraction. Unfortunately, the derivations of these results are often cloaked in several layers of analysis that render them rather…
Path integrals for actions that are not quadratic in their time derivatives
Cahill, Kevin
2015-01-01
The standard way to construct a path integral is to use a Legendre transformation to find the hamiltonian, to repeatedly insert complete sets of states into the time-evolution operator, and then to integrate over the momenta. This procedure is simple when the action is quadratic in its time derivatives, but in most other cases Legendre's transformation is intractable, and the hamiltonian is unknown. This paper shows how to make path integrals without using the hamiltonian.
Space-Time Fractional Diffusion-Advection Equation with Caputo Derivative
Directory of Open Access Journals (Sweden)
José Francisco Gómez Aguilar
2014-01-01
Full Text Available An alternative construction for the space-time fractional diffusion-advection equation for the sedimentation phenomena is presented. The order of the derivative is considered as 0<β, γ≤1 for the space and time domain, respectively. The fractional derivative of Caputo type is considered. In the spatial case we obtain the fractional solution for the underdamped, undamped, and overdamped case. In the temporal case we show that the concentration has amplitude which exhibits an algebraic decay at asymptotically large times and also shows numerical simulations where both derivatives are taken in simultaneous form. In order that the equation preserves the physical units of the system two auxiliary parameters σx and σt are introduced characterizing the existence of fractional space and time components, respectively. A physical relation between these parameters is reported and the solutions in space-time are given in terms of the Mittag-Leffler function depending on the parameters β and γ. The generalization of the fractional diffusion-advection equation in space-time exhibits anomalous behavior.
Multiserver queue with semi-Markovian batch arrivals with application to the MPEG frame sequence
Takagi, Hideaki; Wu, De-An
2002-07-01
We consider a queueing system consisting of multiple identical servers and a common queue. The service time follows an exponential distribution and the arrival process is governed by a semi-Markov process (SMP). The motivation to study the queueing system with SMP arrivals lies in that it can model the auto-correlated traffic on the high speed network generated by a real time communication, for example, the MPEG-encoded VBR video. Our analysis is based on the theory of piecewise Markov process. We first derive the distributions of the queue size and the waiting time. When the sojourn time of SMP follows an exponential distribution all the unknown constants contained in the generating function of queue size can be determined through the zeros of the denominator for this generating function. Based on the result of the analysis, we propose a model to evaluate the waiting time of MPEG video traffic on an ATM network with multiple channels. Here, the SMP corresponds to the exact MPEG sequence of frames. Finally, a numerical example using a real video data is shown.
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
The best time for feasting on hairy crab is only for a short period of time in autumn,so don’t miss out on this unparalleled delicacy. Zen has prepared a variety of dishes made from the crab. Gift boxes and gift vouchers are also available for your friends and family.
DEFF Research Database (Denmark)
Zhou, H. W.; Yi, H. Y.; Mishnaevsky, Leon
2016-01-01
A modeling approach to time-dependent property of Glass Fiber Reinforced Polymers (GFRP) composites is of special interest for quantitative description of long-term behavior. An electronic creep machine is employed to investigate the time-dependent deformation of four specimens of dog......-bond-shaped GFRP composites at various stress level. A negative exponent function based on structural changes is introduced to describe the damage evolution of material properties in the process of creep test. Accordingly, a new creep constitutive equation, referred to fractional derivative Maxwell model...... by the fractional derivative Maxwell model proposed in the paper are in a good agreement with the experimental data. It is shown that the new creep constitutive model proposed in the paper needs few parameters to represent various time-dependent behaviors....
Evaluation of deriving fire cycle of forested landscape based on time-since-fire distribution
Institute of Scientific and Technical Information of China (English)
ZHANG Quan-fa; Kurt S. Pregitzer; JIANG Ming-xi; CHEN Wen-jun
2006-01-01
Estimation of fire cycle has been conducted by using the negative exponential function as an approximation of time-since-fire distribution of a landscape assumed .to be homogeneous with respect to fire spread processes. The authors imposed predefined fire cycles on a virtual landscape of 100 cell ×100 cell, and obtained a mosaic composing of patches with different stand ages (i.e. time since fire). Graphical and statistical methods (Van Wagner 1978; Reed et al. 1998) were employed to derive fire cycle from the virtual landscape. By comparing the predefined and the derived fire cycles, the two methods and tested the effects of sample size and hazard of burning (i.e., stand's susceptibility to fire in relation to its stand age) were evaluated on fire cycle deviation. The simulation results indicated a minimum sample size of 10 times of the annual burnt area would be required for partitioning time-since-fire distribution into homogeneous epochs indicating temporal change in fire cycle. Statistically, there was significant difference among the imposed and the derived fire cycle, regardless of sample sizes with or without consideration of hazard of burning. Both methods underestimated the more recent fire cycle without significant difference between them. The results imply that deviation of fire cycle based on time-since-fire distribution warrants cautious interpretation, especially when a landscape is spatially partitioned into small units and temporal changes in fire cycle are involved.
Efficient algorithms for optimal arrival scheduling and air traffic flow management
Saraf, Aditya
search for optimal trajectories to be flown by each aircraft so that the flows commanded by the outer control-module are achieved. The two-level control system is tested in a dynamic simulation. Furthermore, as a component of the Eulerian part of this two-level system, we present a method for deriving an aggregate airspace-model in real-time, without depending on online integration of aircraft trajectories. This method uses a baseline Eulerian airspace-model, which is derived offline using historical track-data. In real-time, parameters of this model are adapted depending on the differences between the baseline-model and the real-world. This book-keeping based model-derivation indirectly retains some trajectory information. Hence, it serves as an excellent trade-off between Eulerian and trajectory-based modeling approaches. Most importantly, as a vital improvement over previous approaches, we take into consideration the control-dependent nature of the Eulerian-model while computing optimal flow-control decisions. As a proof of concept, we derive a baseline model for the Fort-Worth center and adapt it to predict sector-counts for another set of air traffic data. We also demonstrate the use of this model in a simulation-based optimization scheme for regulating the arrival flow at the Dallas Fort-Worth airport. An application to optimal re-routing strategy computation is also presented.
Estimation for Traffic Arrival Rate and Service Rate of Primary Users in Cognitive Radio Networks
Institute of Scientific and Technical Information of China (English)
Xiaolong Yang; Xuezhi Tan∗
2015-01-01
In order to estimate the traffic arrival rate and service rate parameters of primary users in cognitive radio networks, a hidden Markov model estimation algorithm ( HMM⁃EA) is proposed, which can provide better estimation performance than the energy detection estimation algorithm ( ED⁃EA ) . Firstly, spectrum usage behaviors of primary users are described by establishing a preemptive priority queue model, by which a real state transition probability matrix is derived. Secondly, cooperative detection is utilized to detect the real state of primary users and emission matrix is derived by considering both detection and false alarm probability. Then, a hidden Markov model is built based on the previous two steps, and evaluated through the forward⁃backward algorithm. Finally, the simulations results verify that the HMM⁃EA algorithm outperforms the ED⁃EA in terms of convergence performance, and therefore the secondary user is able to access the unused channel with the least busy probability in real time.
Zhou, H. W.; Yi, H. Y.; Mishnaevsky, L.; Wang, R.; Duan, Z. Q.; Chen, Q.
2016-08-01
A modeling approach to time-dependent property of Glass Fiber Reinforced Polymers (GFRP) composites is of special interest for quantitative description of long-term behavior. An electronic creep machine is employed to investigate the time-dependent deformation of four specimens of dog-bond-shaped GFRP composites at various stress level. A negative exponent function based on structural changes is introduced to describe the damage evolution of material properties in the process of creep test. Accordingly, a new creep constitutive equation, referred to fractional derivative Maxwell model, is suggested to characterize the time-dependent behavior of GFRP composites by replacing Newtonian dashpot with the Abel dashpot in the classical Maxwell model. The analytic solution for the fractional derivative Maxwell model is given and the relative parameters are determined. The results estimated by the fractional derivative Maxwell model proposed in the paper are in a good agreement with the experimental data. It is shown that the new creep constitutive model proposed in the paper needs few parameters to represent various time-dependent behaviors.
Queuing model of a traffic bottleneck with bimodal arrival rate
Woelki, Marko
2016-06-01
This paper revisits the problem of tuning the density in a traffic bottleneck by reduction of the arrival rate when the queue length exceeds a certain threshold, studied recently for variants of totally asymmetric simple exclusion process (TASEP) and Burgers equation. In the present approach, a simple finite queuing system is considered and its contrasting “phase diagram” is derived. One can observe one jammed region, one low-density region and one region where the queue length is equilibrated around the threshold. Despite the simplicity of the model the physics is in accordance with the previous approach: The density is tuned at the threshold if the exit rate lies in between the two arrival rates.
Directory of Open Access Journals (Sweden)
Abdon Atangana
2014-01-01
Full Text Available The notion of uncertainty in groundwater hydrology is of great importance as it is known to result in misleading output when neglected or not properly accounted for. In this paper we examine this effect in groundwater flow models. To achieve this, we first introduce the uncertainties functions u as function of time and space. The function u accounts for the lack of knowledge or variability of the geological formations in which flow occur (aquifer in time and space. We next make use of Riemann-Liouville fractional derivatives that were introduced by Kobelev and Romano in 2000 and its approximation to modify the standard version of groundwater flow equation. Some properties of the modified Riemann-Liouville fractional derivative approximation are presented. The classical model for groundwater flow, in the case of density-independent flow in a uniform homogeneous aquifer is reformulated by replacing the classical derivative by the Riemann-Liouville fractional derivatives approximations. The modified equation is solved via the technique of green function and the variational iteration method.
Approximate self-similar solutions to a nonlinear diffusion equation with time-fractional derivative
Płociniczak, Łukasz; Okrasińska, Hanna
2013-10-01
In this paper, we consider a fractional nonlinear problem for anomalous diffusion. The diffusion coefficient we use is of power type, and hence the investigated problem generalizes the porous-medium equation. A generalization is made by introducing a fractional time derivative. We look for self-similar solutions for which the fractional setting introduces other than classical space-time scaling. The resulting similarity equations are of nonlinear integro-differential type. We approximate these equations by an expansion of the integral operator and by looking for solutions in a power function form. Our method can be easily adapted to solve various problems in self-similar diffusion. The approximations obtained give very good results in numerical analysis. Their simplicity allows for easy use in applications, as our fitting with experimental data shows. Moreover, our derivation justifies theoretically some previously used empirical models for anomalous diffusion.
Observability and confidence of stability and control derivatives determined in real time
Noriega, Alfonso
Stability and control derivatives of an aircraft were estimated from real flight test data in real time. A higher language block diagram library was developed for this purpose. Parameter identification techniques and requirements were used to detect and rate maneuvers present in the data. These ratings were used to blend newly calculated derivatives with previously known values by means of a Kalman filter. The Kalman filter output was used to identify the health of control surfaces actuators. Statistical and measured data were used to predict the probability that an actuator failure has occurred at any given time during the flight. Sweeps of all the tuning parameters of the system were performed, and it was demonstrated that these tuning parameters can be used to obtain the desired performance based on requirements.
Quantum-like picture for intrinsic, classical, arrival distributions
Energy Technology Data Exchange (ETDEWEB)
Torres-Vega, Gabino [Physics Department, Cinvestav, Apdo. postal 14-740, 07000 Mexico D.F. (Mexico)], E-mail: gabino@fis.cinvestav.mx
2009-11-20
We introduce a marginal, quantum-like picture for the arrival of classical quantities in which the representation vectors are the quantities that evolve and probability densities remain static. The representation functions can be seen as probe functions which are the evolution of delta functions with support on a curve in phase space, the time fronts. This procedure provides a classical analog as well as a clear physical interpretation of the 'time eigenstates' used in quantum systems.
Derivation and application of time step model in solidification process simulation
2007-01-01
The heat transfer during the casting solidification process includes the heat radiation of the high temperature casting and the mold, the heat convection between the casting and the mold, and the heat conduction inside the casting and from the casting to the mold. In this paper, a formula of time step in simulation of solidification is derived, considering the heat radiation, convection and conduction based on the conservation of energy. The different heat transfer conditions between the conv...
Gencoglu, Muharrem Tuncay; Baskonus, Haci Mehmet; Bulut, Hasan
2017-01-01
The main aim of this manuscript is to obtain numerical solutions for the nonlinear model of interpersonal relationships with time fractional derivative. The variational iteration method is theoretically implemented and numerically conducted only to yield the desired solutions. Numerical simulations of desired solutions are plotted by using Wolfram Mathematica 9. The authors would like to thank the reviewers for their comments that help improve the manuscript.
Phase difference of arrival geolocation
Energy Technology Data Exchange (ETDEWEB)
Mason, John J.; Romero, Louis (
2017-05-16
Geolocation is performed by receiving, at a plurality of non-earthbound platforms each moving in a known manner within a spatial coordinate system, a radio frequency (RF) signal transmitted from a transmitter at an unknown location on earth within the spatial coordinate system. For each of the platforms, a phase change of the received frequency carrier is measured over the same duration of time. The measured phase changes are combined to determine the transmitter location.
Separation Assurance and Scheduling Coordination in the Arrival Environment
Aweiss, Arwa S.; Cone, Andrew C.; Holladay, Joshua J.; Munoz, Epifanio; Lewis, Timothy A.
2016-01-01
Separation assurance (SA) automation has been proposed as either a ground-based or airborne paradigm. The arrival environment is complex because aircraft are being sequenced and spaced to the arrival fix. This paper examines the effect of the allocation of the SA and scheduling functions on the performance of the system. Two coordination configurations between an SA and an arrival management system are tested using both ground and airborne implementations. All configurations have a conflict detection and resolution (CD&R) system and either an integrated or separated scheduler. Performance metrics are presented for the ground and airborne systems based on arrival traffic headed to Dallas/ Fort Worth International airport. The total delay, time-spacing conformance, and schedule conformance are used to measure efficiency. The goal of the analysis is to use the metrics to identify performance differences between the configurations that are based on different function allocations. A surveillance range limitation of 100 nmi and a time delay for sharing updated trajectory intent of 30 seconds were implemented for the airborne system. Overall, these results indicate that the surveillance range and the sharing of trajectories and aircraft schedules are important factors in determining the efficiency of an airborne arrival management system. These parameters are not relevant to the ground-based system as modeled for this study because it has instantaneous access to all aircraft trajectories and intent. Creating a schedule external to the CD&R and the scheduling conformance system was seen to reduce total delays for the airborne system, and had a minor effect on the ground-based system. The effect of an external scheduler on other metrics was mixed.
Does pet arrival trigger prosocial behaviors in individuals with autism?
Directory of Open Access Journals (Sweden)
Marine Grandgeorge
Full Text Available Alteration of social interactions especially prosocial behaviors--an important aspect of development--is one of the characteristics of autistic disorders. Numerous strategies or therapies are used to improve communication skills or at least to reduce social impairments. Animal-assisted therapies are used widely but their relevant benefits have never been scientifically evaluated. In the present study, we evaluated the association between the presence or the arrival of pets in families with an individual with autism and the changes in his or her prosocial behaviors. Of 260 individuals with autism--on the basis of presence or absence of pets--two groups of 12 individuals and two groups of 8 individuals were assigned to: study 1 (pet arrival after age of 5 versus no pet and study 2 (pet versus no pet, respectively. Evaluation of social impairment was assessed at two time periods using the 36-items ADI-R algorithm and a parental questionnaire about their child-pet relationships. The results showed that 2 of the 36 items changed positively between the age of 4 to 5 (t(0 and time of assessment (t(1 in the pet arrival group (study 1: "offering to share" and "offering comfort". Interestingly, these two items reflect prosocial behaviors. There seemed to be no significant changes in any item for the three other groups. The interactions between individuals with autism and their pets were more--qualitatively and quantitatively--reported in the situation of pet arrival than pet presence since birth. These findings open further lines of research on the impact of pet's presence or arrival in families with an individual with autism. Given the potential ability of individuals with autism to develop prosocial behaviors, related studies are needed to better understand the mechanisms involved in the development of such child-pet relationship.
Does pet arrival trigger prosocial behaviors in individuals with autism?
Grandgeorge, Marine; Tordjman, Sylvie; Lazartigues, Alain; Lemonnier, Eric; Deleau, Michel; Hausberger, Martine
2012-01-01
Alteration of social interactions especially prosocial behaviors--an important aspect of development--is one of the characteristics of autistic disorders. Numerous strategies or therapies are used to improve communication skills or at least to reduce social impairments. Animal-assisted therapies are used widely but their relevant benefits have never been scientifically evaluated. In the present study, we evaluated the association between the presence or the arrival of pets in families with an individual with autism and the changes in his or her prosocial behaviors. Of 260 individuals with autism--on the basis of presence or absence of pets--two groups of 12 individuals and two groups of 8 individuals were assigned to: study 1 (pet arrival after age of 5 versus no pet) and study 2 (pet versus no pet), respectively. Evaluation of social impairment was assessed at two time periods using the 36-items ADI-R algorithm and a parental questionnaire about their child-pet relationships. The results showed that 2 of the 36 items changed positively between the age of 4 to 5 (t(0)) and time of assessment (t(1)) in the pet arrival group (study 1): "offering to share" and "offering comfort". Interestingly, these two items reflect prosocial behaviors. There seemed to be no significant changes in any item for the three other groups. The interactions between individuals with autism and their pets were more--qualitatively and quantitatively--reported in the situation of pet arrival than pet presence since birth. These findings open further lines of research on the impact of pet's presence or arrival in families with an individual with autism. Given the potential ability of individuals with autism to develop prosocial behaviors, related studies are needed to better understand the mechanisms involved in the development of such child-pet relationship.
14 CFR 93.27 - Sale and lease of Arrival Authorizations.
2010-01-01
..., and request that the buyer/lessee and the seller/lessor submit to the FAA the information (such as... purchase an Arrival Authorization at O'Hare. The Carrier may submit information in writing or via the FAA's... information in writing to the FAA: (1) Arrival Authorization number and time; (2) Frequency; (3) Planned...
Factors Associated with Early Hospital Arrival in Patients with Acute Ischemic Stroke.
Song, Dongbeom; Tanaka, Eijirou; Lee, Kijeong; Sato, Shoichiro; Koga, Masatoshi; Kim, Young Dae; Nagatsuka, Kazuyuki; Toyoda, Kazunori; Heo, Ji Hoe
2015-05-01
Factors associated with early arrival may vary according to the characteristics of the hospital. We investigated the factors associated with early hospital arrival in two different stroke centers located in Korea and Japan. Consecutive patients with ischemic stroke arrived hospital within 48 hours of onset between January 2011 and December 2012 were identified and the clinical and time variables were retrieved from the prospective stroke registries of Severance Hospital of Yonsei University Health System (YUHS; Seoul, Korea) and National Cerebral and Cardiovascular Center (NCVC; Osaka, Japan). Subjects were dichotomized into early (time from onset to arrival ≤4.5 hours) and late (>4.5 hours) arrival groups. Univariate and multivariate analyses were performed to evaluate factors associated with early hospital arrival. A total of 1,966 subjects (992 from YUHS; 974 from NCVC) were included in this study. The median time from onset to arrival was 6.1 hours [interquartile range, 1.7-17.8 hours]. In multivariate analysis, the factors associated with early arrival were atrial fibrillation (Odds ratio [OR], 1.505; 95% confidence interval [CI], [1.168-1.939]), higher initial National Institute of Health Stroke Scale scores (OR, 1.037; 95% CI [1.023-1.051]), onset during daytime (OR, 2.799; 95% CI [2.173-3.605]), and transport by an emergency medical service (OR, 2.127; 95% CI [1.700-2.661]). These factors were consistently associated with early arrival in both hospitals. Despite differences between the hospitals, there were common factors related to early arrival. Efforts to identify and modify these factors may promote early hospital arrival and improve stroke outcome.
Investigation of the 16-year and 18-year ZTD Time Series Derived from GPS Data Processing
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Bałdysz Zofia
2015-08-01
Full Text Available The GPS system can play an important role in activities related to the monitoring of climate. Long time series, coherent strategy, and very high quality of tropospheric parameter Zenith Tropospheric Delay (ZTD estimated on the basis of GPS data analysis allows to investigate its usefulness for climate research as a direct GPS product. This paper presents results of analysis of 16-year time series derived from EUREF Permanent Network (EPN reprocessing performed by the Military University of Technology. For 58 stations Lomb-Scargle periodograms were performed in order to obtain information about the oscillations in ZTD time series. Seasonal components and linear trend were estimated using Least Square Estimation (LSE and Mann-Kendall trend test was used to confirm the presence of a linear trend designated by LSE method. In order to verify the impact of the length of time series on trend value, comparison between 16 and 18 years were performed
Using Time Series Segmentation for Deriving Vegetation Phenology Indices from MODIS NDVI Data
Energy Technology Data Exchange (ETDEWEB)
Chandola, Varun [ORNL; Vatsavai, Raju [ORNL; Hui, Dafeng [ORNL; Gu, Lianhong [ORNL; Bhaduri, Budhendra L [ORNL
2010-01-01
Characterizing vegetation phenology is a highly significant problem, due to its importance in regulating ecosystem carbon cycling, interacting with climate changes, and decision-making of croplands managements. While ground based sensors, such as the AmeriFlux sensors, can provide measurements at high temporal resolution (every hour) and can be used to accurately calculate vegetation phenology indices, they are limited to only a few sites. Remote sensing data, such as the Normalized Difference Vegetation Index (NDVI), collected using the MODerate Resolution Imaging Spectroradiometer (MODIS), can provide global coverage, though at a much coarser temporal resolution (16 days). In this study we use data mining based time series segmentation methods to derive phenology indices from NDVI data, and compare it with the phenology indices derived from the AmeriFlux data using a widely used model fitting approach. Results show a significant correlation (as high as 0.60) between the indices derived from these two different data sources. This study demonstrates that data driven methods can be effectively employed to provide realistic estimates of vegetation phenology indices using periodic time series data and has the potential to be used at large spatial scales and for long-term remote sensing data.
A CATASTROPHIC-CUM-RESTORATIVE QUEUING SYSTEM WITH CORRELATED BATCH ARRIVALS AND VARIABLE CAPACITY
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Rakesh Kumar
2008-07-01
Full Text Available In this paper, we study a catastrophic-cum-restorative queuing system with correlated batch arrivals and service in batches of variable sizes. We perform the transient analysis of the queuing model. We obtain the Laplace Transform of the probability generating function of system size. Finally, some particular cases of the model have been derived and discussed. Keywords: Queue length, Catastrophes, Correlated batch arrivals, Broadband services, Variable service capacity, and Restoration.
Anaïs Schaeffer
2012-01-01
In 1970, CERN and ESO signed a collaboration agreement for the construction of the Observatory’s first telescope. That same year, ESO’s Telescope Division and Sky Atlas laboratory settled on the CERN site in Meyrin. Let’s turn back to the beginnings of this lasting and fruitful alliance. Martin Cullum, ESO physicist from 1973 to 2009 In 1974, when I attended my first international conference on behalf of ESO, the first thing people asked was: “Where are you from?” “ESO,” I would say. The response: ‘'What on Earth is ESO?” Nowadays, people I meet seem to know more about ESO than I do! It is clear that ESO profited enormously from its sojourn at CERN. The wise decision of the ESO Director General at the time, Adriaan Blaauw, to move to Geneva allowed ESO to build up its technical expertise to be able to build world-beating projects like the VLT, which has undoubtedly been the most exciting scientif...
Research Of Airborne Precision Spacing to Improve Airport Arrival Operations
Barmore, Bryan E.; Baxley, Brian T.; Murdoch, Jennifer L.
2011-01-01
In September 2004, the European Organization for the Safety of Air Navigation (EUROCONTROL) and the United States Federal Aviation Administration (FAA) signed a Memorandum of Cooperation to mutually develop, modify, test, and evaluate systems, procedures, facilities, and devices to meet the need for safe and efficient air navigation and air traffic control in the future. In the United States and Europe, these efforts are defined within the architectures of the Next Generation Air Transportation System (NextGen) Program and Single European Sky Air Traffic Management Research (SESAR) Program respectively. Both programs have identified Airborne Spacing as a critical component, with Automatic Dependent Surveillance Broadcast (ADS-B) as a key enabler. Increased interest in reducing airport community noise and the escalating cost of aviation fuel has led to the use of Continuous Descent Arrival (CDA) procedures to reduce noise, emissions, and fuel usage compared to current procedures. To provide these operational enhancements, arrival flight paths into terminal areas are planned around continuous vertical descents that are closer to an optimum trajectory than those in use today. The profiles are designed to be near-idle descents from cruise altitude to the Final Approach Fix (FAF) and are typically without any level segments. By staying higher and faster than conventional arrivals, CDAs also save flight time for the aircraft operator. The drawback is that the variation of optimized trajectories for different types and weights of aircraft requires the Air Traffic Controller to provide more airspace around an aircraft on a CDA than on a conventional arrival procedure. This additional space decreases the throughput rate of the destination airport. Airborne self-spacing concepts have been developed to increase the throughput at high-demand airports by managing the inter-arrival spacing to be more precise and consistent using on-board guidance. It has been proposed that the
Storm time equatorial magnetospheric ion temperature derived from TWINS ENA flux
Katus, R. M.; Keesee, A. M.; Scime, E.; Liemohn, M. W.
2017-04-01
The plasma sheet plays an integral role in the transport of energy from the magnetotail to the ring current. We present a comprehensive study of the equatorial magnetospheric ion temperatures derived from Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) energetic neutral atom (ENA) measurements during moderate to intense (Dstpeak Los Alamos National Laboratory magnetospheric plasma analyzer. The ion temperatures are analyzed as a function of storm time, local time, and L shell. We perform a normalized superposed epoch analysis of 48 geomagnetic storms and examine the spatial and temporal evolution of the plasma as a function of storm phase. This analysis illustrates the spatial and temporal variation of the ions from the plasma sheet into the inner magnetosphere. We find that the ion temperature increases approaching the storm peak. This enhancement has the largest magnetic local time extent near 12 RE distance downtail.
Analysis of electric vehicle's trip cost without late arrival
Leng, Jun-Qiang; Zhao, Lin
2017-03-01
In this paper, we use a car-following model to study each electric vehicle's trip cost and the corresponding total trip cost without late arrival. The numerical result show that the electricity cost has significant effects on each electric vehicle's trip cost and the corresponding total trip costs and that the effects are dependent on its time headway at the origin, but the electricity cost has no prominent effects on the minimum value of the system's total trip cost.
Directory of Open Access Journals (Sweden)
R. R. Ilma
2012-01-01
Full Text Available A correlation of the ionospheric electric field and the time derivative of the magnetic field was noticed over thirty years ago and has yet to be explained. Here we report on another set of examples during the superstorm of November 2004. The electric field in the equatorial ionosphere, measured with the Jicamarca incoherent scatter radar, exhibited a 3 mV/m electric field pulse that was not seen in the interplanetary medium. It was, however, accompanied by a correlation with the time derivative of the magnetic field measured at two points in Peru. Our inclination was to assume that the field was inductive. However, the time scale of the pulse was too short for the magnetic field to penetrate the crust of the Earth. This means that the area threaded by ∂B/∂t was too small to create the observed electric field by induction. We suggest that the effect was caused by a modulation of the ring current location relative to the Earth due to the electric field. This electric field is required, as the magnetic field lines are considered frozen into the plasma in the magnetosphere. The closer location of the ring current to the Earth in turn increased the magnetic field at the surface.
Feedlot Processing and Arrival Cattle Management.
Noffsinger, Tom; Lukasiewicz, Kip; Hyder, LeeAnn
2015-11-01
Acclimating newly arrived cattle in a feedlot setting can increase cattle confidence, reduce stress, improve immune function, and increase cattle well-being. Understanding cattle instincts and using low-stress handling techniques teaches cattle to trust their caregivers and work efficiently for them throughout the feeding period. These techniques should be applied with newly arrived cattle when they are unloaded, moved from the holding pen to the home pen, and handled inside the home pen. Low-stress handling during processing and a sound processing protocol based on cattle history and proper risk assessment can improve cattle health from the start of the feeding period.
2014-01-01
Time derivative estimation of signals plays a very important role in several fields, such as signal processing and control engineering, just to name a few of them. For that purpose, a non-asymptotic algebraic procedure for the approximate estimation of the system states is used in this work. The method is based on results from differential algebra and furnishes some general formulae for the time derivatives of a measurable signal in which two algebraic derivative estimators run simultaneously...
Young, E. V.; Muto, A.; Babcock, E.
2016-12-01
Monitoring the mass balance of alpine glaciers is important because alpine glaciers presently account for about half of the cryospheric contribution to the global sea-level rise. Mass balance measurements of alpine glaciers have predominantly relied upon glaciological and hydrological methods. However, these methods can be logistically costly and have potential extrapolation errors. Remote sensing approaches, such as gravimetric methods using data from GRACE satellite missions, have provided monthly mass-balance estimates of aggregates of alpine glaciers but their spatial resolution is far too large for studying a single glacier. On the other hand, ground-based time-lapse microgravity geophysical measurements can potentially circumvent some of the disadvantages of the glaciological and hydrological methods. It may detect the change in a single glacier's mass and its spatial distribution. We conducted ground-based time-lapse microgravity surveys on Wolverine Glacier, Alaska, in May and August of 2016, using a Scintrex CG-5 Autograv gravimeter. We collected data at seventy-nine individual stations on the glacier, roughly five stations per square kilometer. We included repeat-station and base-station measurements made at least twice a day for instrumental drift control. The uncertainty of our gravity measurements is better than 0.03 mGal, which is about 0.7 meters water equivalent of surface mass balance. Our summer-time mass balance of Wolverine Glacier determined from the time-lapse gravity measurements is independent of that derived from the stake-network or stream-gauge measurements, and could provide spatial insight into the mass balance process on Wolverine Glacier and similar glaciers.
Directory of Open Access Journals (Sweden)
S. Das
2013-12-01
Full Text Available In this article, optimal homotopy-analysis method is used to obtain approximate analytic solution of the time-fractional diffusion equation with a given initial condition. The fractional derivatives are considered in the Caputo sense. Unlike usual Homotopy analysis method, this method contains at the most three convergence control parameters which describe the faster convergence of the solution. Effects of parameters on the convergence of the approximate series solution by minimizing the averaged residual error with the proper choices of parameters are calculated numerically and presented through graphs and tables for different particular cases.
Design Principles and Algorithms for Air Traffic Arrival Scheduling
Erzberger, Heinz; Itoh, Eri
2014-01-01
This report presents design principles and algorithms for building a real-time scheduler of arrival aircraft based on a first-come-first-served (FCFS) scheduling protocol. The algorithms provide the conceptual and computational foundation for the Traffic Management Advisor (TMA) of the Center/terminal radar approach control facilities (TRACON) automation system, which comprises a set of decision support tools for managing arrival traffic at major airports in the United States. The primary objective of the scheduler is to assign arrival aircraft to a favorable landing runway and schedule them to land at times that minimize delays. A further objective of the scheduler is to allocate delays between high-altitude airspace far away from the airport and low-altitude airspace near the airport. A method of delay allocation is described that minimizes the average operating cost in the presence of errors in controlling aircraft to a specified landing time. This report is a revision of an earlier paper first presented as part of an Advisory Group for Aerospace Research and Development (AGARD) lecture series in September 1995. The authors, during vigorous discussions over the details of this paper, felt it was important to the air-trafficmanagement (ATM) community to revise and extend the original 1995 paper, providing more detail and clarity and thereby allowing future researchers to understand this foundational work as the basis for the TMA's scheduling algorithms.
Analysis of sequencing and scheduling methods for arrival traffic
Neuman, Frank; Erzberger, Heinz
1990-01-01
The air traffic control subsystem that performs scheduling is discussed. The function of the scheduling algorithms is to plan automatically the most efficient landing order and to assign optimally spaced landing times to all arrivals. Several important scheduling algorithms are described and the statistical performance of the scheduling algorithms is examined. Scheduling brings order to an arrival sequence for aircraft. First-come-first-served scheduling (FCFS) establishes a fair order, based on estimated times of arrival, and determines proper separations. Because of the randomness of the traffic, gaps will remain in the scheduled sequence of aircraft. These gaps are filled, or partially filled, by time-advancing the leading aircraft after a gap while still preserving the FCFS order. Tightly scheduled groups of aircraft remain with a mix of heavy and large aircraft. Separation requirements differ for different types of aircraft trailing each other. Advantage is taken of this fact through mild reordering of the traffic, thus shortening the groups and reducing average delays. Actual delays for different samples with the same statistical parameters vary widely, especially for heavy traffic.
A space-time hybrid hourly rainfall model for derived flood frequency analysis
Directory of Open Access Journals (Sweden)
U. Haberlandt
2008-12-01
Full Text Available For derived flood frequency analysis based on hydrological modelling long continuous precipitation time series with high temporal resolution are needed. Often, the observation network with recording rainfall gauges is poor, especially regarding the limited length of the available rainfall time series. Stochastic precipitation synthesis is a good alternative either to extend or to regionalise rainfall series to provide adequate input for long-term rainfall-runoff modelling with subsequent estimation of design floods. Here, a new two step procedure for stochastic synthesis of continuous hourly space-time rainfall is proposed and tested for the extension of short observed precipitation time series.
First, a single-site alternating renewal model is presented to simulate independent hourly precipitation time series for several locations. The alternating renewal model describes wet spell durations, dry spell durations and wet spell intensities using univariate frequency distributions separately for two seasons. The dependence between wet spell intensity and duration is accounted for by 2-copulas. For disaggregation of the wet spells into hourly intensities a predefined profile is used. In the second step a multi-site resampling procedure is applied on the synthetic point rainfall event series to reproduce the spatial dependence structure of rainfall. Resampling is carried out successively on all synthetic event series using simulated annealing with an objective function considering three bivariate spatial rainfall characteristics. In a case study synthetic precipitation is generated for some locations with short observation records in two mesoscale catchments of the Bode river basin located in northern Germany. The synthetic rainfall data are then applied for derived flood frequency analysis using the hydrological model HEC-HMS. The results show good performance in reproducing average and extreme rainfall characteristics as well as in
Directory of Open Access Journals (Sweden)
Ram K. Saxena
2014-08-01
Full Text Available This paper deals with the investigation of the computational solutions of a unified fractional reaction-diffusion equation, which is obtained from the standard diffusion equation by replacing the time derivative of first order by the generalized Riemann–Liouville fractional derivative defined by others and the space derivative of second order by the Riesz–Feller fractional derivative and adding a function ɸ(x, t. The solution is derived by the application of the Laplace and Fourier transforms in a compact and closed form in terms of Mittag–Leffler functions. The main result obtained in this paper provides an elegant extension of the fundamental solution for the space-time fractional diffusion equation obtained by others and the result very recently given by others. At the end, extensions of the derived results, associated with a finite number of Riesz–Feller space fractional derivatives, are also investigated.
Institute of Scientific and Technical Information of China (English)
余玅妙; 唐应辉; 付永红; 刘强国
2011-01-01
Applying the supplementary variable technique and embedded Markov chain method based on the iteration of conditional probability matrix, we studied a discrete-time GI/D-MSP/1 /N queuing system with negative customer arrival and RCH killing policy. Three kinds of queue length distributions, namely the queue length distribution at positive customer pre-arrival, arbitrary and outside observer's observation epochs, are obtained. Furthermore, we also considered the waiting time distribution of the accessible positive customer. Finally, we presented several numerical examples under some special cases to demonstrate the correctness of the theoretical analysis of this algorithm.%综合运用补充变量方法和基于条件概率矩阵迭代的嵌入Markov链方法研究了具有负顾客到达和RCH移除策略的离散时间GI/D-MSP/1/N排队系统.获得了稳态情形下正顾客到达前夕,任意时隙分点以及外部观测时刻的三种队长分布.并进一步讨论了可入系统正顾客的等待时间分布.最后通过几个特殊情形下的数值算例验证了计算方法理论分析的正确性.
Clustering Time-Series Gene Expression Data Using Smoothing Spline Derivatives
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S. Déjean
2007-06-01
Full Text Available Microarray data acquired during time-course experiments allow the temporal variations in gene expression to be monitored. An original postprandial fasting experiment was conducted in the mouse and the expression of 200 genes was monitored with a dedicated macroarray at 11 time points between 0 and 72 hours of fasting. The aim of this study was to provide a relevant clustering of gene expression temporal profiles. This was achieved by focusing on the shapes of the curves rather than on the absolute level of expression. Actually, we combined spline smoothing and first derivative computation with hierarchical and partitioning clustering. A heuristic approach was proposed to tune the spline smoothing parameter using both statistical and biological considerations. Clusters are illustrated a posteriori through principal component analysis and heatmap visualization. Most results were found to be in agreement with the literature on the effects of fasting on the mouse liver and provide promising directions for future biological investigations.
Interception modeling with vegetation time series derived from Landsat TM data
Polo, M. J.; Díaz-Gutiérrez, A.; González-Dugo, M. P.
2011-11-01
Rainfall interception by the vegetation may constitute a significant fraction in the water budget at local and watershed scales, especially in Mediterranean areas. Different approaches can be found to model locally the interception fraction, but a distributed analysis requires time series of vegetation along the watershed for the study period, which includes both type of vegetation and ground cover fraction. In heterogeneous watersheds, remote sensing is usually the only viable alternative to characterize medium to large size areas, but the high number of scenes necessary to capture the temporal variability during long periods, together with the sometimes extreme scarcity of data during the wet season, make it necessary to deal with a limited number of images and interpolate vegetation maps between consecutive dates. This work presents an interception model for heterogeneous watersheds which combines an interception continuous simulation derived from Gash model and their derivations, and a time series of vegetation cover fraction and type from Landsat TM data and vegetation inventories. A mountainous watershed in Southern Spain where a physical hydrological modelling had been previously calibrated was selected for this study. The dominant species distribution and their relevant characteristics regarding the interception process were analyzed from literature and digital cartography; the evolution of the vegetation cover fraction along the watershed during the study period (2002-2005) was produced by the application of a NDVI analysis on the available scenes of Landsat TM images. This model was further calibrated by field data collected in selected areas in the watershed.
Tran, Hai Nguyen; You, Sheng-Jie; Chao, Huan-Ping
2016-02-01
The mechanism and capacity of adsorption of cadmium (Cd) on orange peel (OP)-derived biochar at various pyrolysis temperatures (400, 500, 600, 700 and 800°C) and heating times (2 and 6 h) were investigated. Biochar was characterized using proximate analysis, point of zero charge (PZC) analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Equilibrium and kinetic experiments of Cd adsorption on biochar were performed. The results indicated that the pH value at PZC of biochar approached 9.5. Equilibrium can be reached rapidly (within 1 min) in kinetic experiments and a removal rate of 80.6-96.9% can be generated. The results fitted the pseudo-second-order model closely. The adsorption capacity was estimated using the Langmuir model. The adsorption capacity of Cd on biochar was independent of the pyrolysis temperature and heating time (p>0.01). The maximum adsorption capacity of Cd was 114.69 (mg g(-1)). The adsorption of Cd on biochar was regarded as chemisorption. The primary adsorption mechanisms were regarded as Cπ-cation interactions and surface precipitation. Cadmium can react with calcite to form the precipitation of (Ca,Cd)CO3 on the surface of biochar. The OP-derived biochar can be considered a favourable alternative and a new green adsorbent for removing Cd(2+) ions from an aqueous solution.
FORECASTING TOURIST ARRIVALS TO LANGKAWI ISLAND MALAYSIA
National Research Council Canada - National Science Library
Kamarul Ariffin MANSOR; Wan Irham ISHAK
2015-01-01
..., food and services industries and their best shape. This study focuses on tourist arrivals in Langkawi Island as one of the major tourist attractions situated in the northerly region of Peninsular Malaysia. Importantly, this paper attempts to measure and compare the performance of forecasting with Exponential Smoothing, ARIMA and ARFIMA models using the R software package.
Christmas Card Arrives 93 Years Late
Institute of Scientific and Technical Information of China (English)
马加芬
2008-01-01
A postcard featuring a color drawing of Santa Claus and a young girl was mailed in 1914, but its jour- ney was slower than Christmas. It just arrived in northwest Kansas. The Christmas card was dated Dec. 23, 1914, and mailed to Ethel Martin of Oberlin, apparently from her cousins in Alma, Neb.
The arrival of the CLOUD chamber
CERN AVC
2009-01-01
The team from the CLOUD experiment - the world’s first experiment using a high-energy particle accelerator to study the climate - were on cloud nine after the arrival of their new three-metre diameter cloud chamber. This marks the end of three years’ R&D; and design, and the start of preparations for data taking later this year.
A finite capacity queue with Markovian arrivals and two servers with group services
Directory of Open Access Journals (Sweden)
S. Chakravarthy
1994-01-01
Full Text Available In this paper we consider a finite capacity queuing system in which arrivals are governed by a Markovian arrival process. The system is attended by two exponential servers, who offer services in groups of varying sizes. The service rates may depend on the number of customers in service. Using Markov theory, we study this finite capacity queuing model in detail by obtaining numerically stable expressions for (a the steady-state queue length densities at arrivals and at arbitrary time points; (b the Laplace-Stieltjes transform of the stationary waiting time distribution of an admitted customer at points of arrivals. The stationary waiting time distribution is shown to be of phase type when the interarrival times are of phase type. Efficient algorithmic procedures for computing the steady-state queue length densities and other system performance measures are discussed. A conjecture on the nature of the mean waiting time is proposed. Some illustrative numerical examples are presented.
Directory of Open Access Journals (Sweden)
Sri Handayani
2010-06-01
Full Text Available The aim of this research is to determine the optimum time of reaction and concentration of hydroxide ion on chalcone, 4-methoxychalcone and 3,4-dimethoxychalcone synthesis. Chalcone and its derivatives were synthesized by dissolving KOH in ethanol followed by dropwise addition of acetophenone and benzaldehyde. Then, the mixture was stirred for several hours. Three benzaldehydes has been used, i.e : benzaldehyde, p-anysaldehyde and veratraldehyde. The time of reaction was varied for, 12, 18, 24, 30 and 36 hours. Furthermore, on the optimum reaction time for each benzaldehyde the hydroxyl ion concentration was varied from 5,7,9,11 and 13%(w/v. The results of this research suggested that the optimum time of chalchone synthesis was 12 hours, while, 4-methoxychalcone and 3,4-dimethoxychalcone were 30 hours. The optimum concentration of hydroxide ion of chalcone synthesis was 13% and for 4-methoxychalcone and 3,4-dimethoxychalcone were 11%. Keywords: Chalcone synthesis, time of reaction, hydroxide ion concentration.
A New Derivation of the Time-Dependent Schr\\"odinger Equation from Wave and Matrix Mechanics
Nanni, Luca
2015-01-01
An alternative method is proposed for deriving the time dependent Schroedinger equation from the pictures of wave and matrix mechanics. The derivation is of a mixed classical quantum character, since time is treated as a classical variable, thus avoiding any controversy over its meaning in quantum mechanics. The derivation method proposed in this paper requires no ad hoc assumption and avoids going through a second-order differential equation that can be reduced to the well known time-dependent Schroedinger equation only postulating a complex wavefunction with an exponential time dependence, as did by Schroedinger in its original paper of 1926.
Robust Analysis of Network-Based Real-Time Kinematic for GNSS-Derived Heights
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Tae-Suk Bae
2015-10-01
Full Text Available New guidelines and procedures for real-time (RT network-based solutions are required in order to support Global Navigation Satellite System (GNSS derived heights. Two kinds of experiments were carried out to analyze the performance of the network-based real-time kinematic (RTK solutions. New test marks were installed in different surrounding environments, and the existing GPS benchmarks were used for analyzing the effect of different factors, such as baseline lengths, antenna types, on the final accuracy and reliability of the height estimation. The RT solutions are categorized into three groups: single-base RTK, multiple-epoch network RTK (mRTN, and single-epoch network RTK (sRTN. The RTK solution can be biased up to 9 mm depending on the surrounding environment, but there was no notable bias for a longer reference base station (about 30 km In addition, the occupation time for the network RTK was investigated in various cases. There is no explicit bias in the solution for different durations, but smoother results were obtained for longer durations. Further investigation is needed into the effect of changing the occupation time between solutions and into the possibility of using single-epoch solutions in precise determination of heights by GNSS.
Robust Analysis of Network-Based Real-Time Kinematic for GNSS-Derived Heights.
Bae, Tae-Suk; Grejner-Brzezinska, Dorota; Mader, Gerald; Dennis, Michael
2015-10-26
New guidelines and procedures for real-time (RT) network-based solutions are required in order to support Global Navigation Satellite System (GNSS) derived heights. Two kinds of experiments were carried out to analyze the performance of the network-based real-time kinematic (RTK) solutions. New test marks were installed in different surrounding environments, and the existing GPS benchmarks were used for analyzing the effect of different factors, such as baseline lengths, antenna types, on the final accuracy and reliability of the height estimation. The RT solutions are categorized into three groups: single-base RTK, multiple-epoch network RTK (mRTN), and single-epoch network RTK (sRTN). The RTK solution can be biased up to 9 mm depending on the surrounding environment, but there was no notable bias for a longer reference base station (about 30 km) In addition, the occupation time for the network RTK was investigated in various cases. There is no explicit bias in the solution for different durations, but smoother results were obtained for longer durations. Further investigation is needed into the effect of changing the occupation time between solutions and into the possibility of using single-epoch solutions in precise determination of heights by GNSS.
Phenological Metrics Derived over the European Continent from NDVI3g Data and MODIS Time Series
Directory of Open Access Journals (Sweden)
Clement Atzberger
2013-12-01
Full Text Available Time series of normalized difference vegetation index (NDVI are important data sources for environmental monitoring. Continuous efforts are put into their production and updating. The recently released Global Inventory Modeling and Mapping Studies (GIMMS NDVI3g data set is a consistent time series with 1/12° spatial and bi-monthly temporal resolution. It covers the time period from 1981 to 2011. However, it is unclear if vegetation density and phenology derived from GIMMS are comparable to those obtained from Moderate Resolution Imaging Spectroradiometer (MODIS NDVI with 250 m ground resolution. To check the consistency between GIMMS and MODIS data sets, a comparative analysis was performed. For a large European window (40 × 40°, data distribution, spatial and temporal agreement were analyzed, as well as the timing of important phenological events. Overall, only a moderately good agreement of NDVI values was found. Large differences occurred during winter. Large discrepancies were also observed for phenological metrics, in particular the start of season. Information regarding the maximum of season was more consistent. Hence, both data sets should be well inter-calibrated before being used concurrently.
1988-05-31
COMPUTER ALGORITHMS FOR AUTOMATIC REAL-TIME DETERMINATION OF SPACE VEHICLE POTENTIALS IN VARIOUS PLASMA ENVIRONMENTS May 31, 1988 Stanley L. Spiegel...crrnaion DiviSiofl 838 12 2 DERIVATION AND TESTING OF COMPUTER ALGORITHMS FOR AUTOMATIC REAL-TIME DETERMINATION OF SPACE VEHICLE POTENTIALS IN VARIOUS...S.L., "Derivation and testing of computer algorithms for automatic real time determination of space vehicle poteuatials in various plasma
Statistical Angle-of-Arrival and Doppler Method for GPS Radio Interferometry of TIDS
Afraimovich, E. L.; Palamartchouk, K. S.; Perevalova, N. P.
A Statistical Angle-of-arrival and Doppler Method for GPS radio interferometry (SADM-GPS) is proposed for determining the characteristics of the Travelling Ionospheric Disturbances (TIDs) by measuring variations of GPS phase derivatives with respect to time and spatial coordinates. These data are used to calculate corresponding values of the velocity vector, in view of a correction for satellite motion based on current information available regarding the angular coordinates of the satellites. Through a computer simulation it was shown that multi satellite GPS radio interferometry in conjunction with the SADM-GPS algorithm allows for detecting and measuring the velocity vector of TIDs in virtually the entire azimuthal range of possible TID propagation directions
A generic probability based algorithm to derive regional patterns of crops in time and space
Wattenbach, Martin; Oijen, Marcel v.; Leip, Adrian; Hutchings, Nick; Balkovic, Juraj; Smith, Pete
2013-04-01
Croplands are not only the key to human food supply, they also change the biophysical and biogeochemical properties of the land surface leading to changes in the water cycle, energy partitioning, influence soil erosion and substantially contribute to the amount of greenhouse gases entering the atmosphere. The effects of croplands on the environment depend on the type of crop and the associated management which both are related to the site conditions, economic boundary settings as well as preferences of individual farmers. However, at a given point of time the pattern of crops in a landscape is not only determined by environmental and socioeconomic conditions but also by the compatibility to the crops which had been grown in the years before at the current field and its surrounding cropping area. The crop compatibility is driven by factors like pests and diseases, crop driven changes in soil structure and timing of cultivation steps. Given these effects of crops on the biochemical cycle and their interdependence with the mentioned boundary conditions, there is a demand in the regional and global modelling community to account for these regional patterns. Here we present a Bayesian crop distribution generator algorithm that is used to calculate the combined and conditional probability for a crop to appear in time and space using sparse and disparate information. The input information to define the most probable crop per year and grid cell is based on combined probabilities derived from the a crop transition matrix representing good agricultural practice, crop specific soil suitability derived from the European soil database and statistical information about harvested area from the Eurostat database. The reported Eurostat crop area also provides the target proportion to be matched by the algorithm on the level of administrative units (Nomenclature des Unités Territoriales Statistiques - NUTS). The algorithm is applied for the EU27 to derive regional spatial and
Convergence Acceleration of the Navier-Stokes Equations Through Time-Derivative Preconditioning
Merkle, Charles L.; Venkateswaran, Sankaran; Deshpande, Manish
1996-01-01
Chorin's method of artificial compressibility is extended to both compressible and incompressible fluids by using physical arguments to define artificial fluid properties that make up a local preconditioning matrix. In particular, perturbation expansions are used to provide appropriate temporal derivatives for the equations of motion at both low speeds and low Reynolds numbers. These limiting forms are then combined into a single function that smoothly merges into the physical time derivatives at high speeds so that the equations are left unchanged at transonic, high Reynolds number conditions. The effectiveness of the resulting preconditioning procedures for the Navier-Stokes equations is demonstrated for a wide speed and Reynolds number ranges by means of stability results and computational solutions. Nevertheless, the preconditioned equations sometimes fail to provide a solution for applications for which the non-preconditioned equations converge. Often this is because the reduced dissipation in the preconditioned equations results in an unsteady solution while the more dissipative non-preconditioned equations result in a steady state. Problems of this type represent a computational challenge; it is important to distinguish between non-convergence of algorithms, and the non-existence of steady state solutions.
Ryabinkin, Ilya G; Izmaylov, Artur F
2015-01-01
We have developed a numerical differentiation scheme which eliminates evaluation of overlap determinants in calculating the time-derivative non-adiabatic couplings (TDNACs). Evaluation of these determinants was a bottleneck in previous implementations of mixed quantum-classical methods using numerical differentiation of electronic wave functions in the Slater-determinant representation. The central idea of our approach is, first, to reduce the analytic time derivatives of Slater determinants to time derivatives of molecular orbitals, and then to apply a finite-difference formula. Benchmark calculations prove the efficiency of the proposed scheme showing impressive several-order-of-magnitude speedups of the TDNAC calculation step for midsize molecules.
Derivation and application of time step model in solidification process simulation
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The heat transfer during the casting solidification process includes the heat radiation of the high temperature casting and the mold, the heat convection between the casting and the mold, and the heat conduction inside the casting and from the casting to the mold. In this paper, a formula of time step in simulation of solidification is derived, considering the heat radiation, convection and conduction based on the conservation of energy. The different heat transfer conditions between the conventional sand casting and the permanent mold casting are taken into account in this formula. The characteristics of heat transfer in the interior and surface of the casting are also considered. The numerical experiments show that this formula can avoid computational dispersion, and improve the computational efficiency by about 20% in the simulation of solidification process.
Chinese Calligraphy Word Spotting Using Elastic HOG Feature and Derivative Dynamic Time Warping
Institute of Scientific and Technical Information of China (English)
Yong Xia; Zhi-Bo Yang; Kuan-Quan Wang
2014-01-01
Chinese calligraphy is a very special style of handwriting and direct character recognition is very difficult. Content-based keyword spotting is more feasible than recognition-based retrieval for calligraphy document. In this paper, we propose a novel Elastic Histogram of Oriented Gradient ( EHOG) descriptor for calligraphy word spotting. The presented feature is a modification of Histogram of Oriented Gradient (HOG), widely used in human detection. In our approach, the input word image is partitioned into non-uniform rectangular cells according to the calligraphy character pixel intensity, and then in each cell a histogram of orientation is accumulated dynamically. Moreover, we adopt Derivative Dynamic Time Warping ( DDTW) for image feature matching, which achieves good performance in gesture recognition. Experiments demonstrate a very significant improvement when comparing our proposed feature with previously developed ones, and also show DDTW produces superior alignments between two calligraphy character feature series than DTW.
Derivation and application of time step model in solidification process simulation
Directory of Open Access Journals (Sweden)
GONG Wen-bang
2007-08-01
Full Text Available The heat transfer during the casting solidification process includes the heat radiation of the high temperature casting and the mold, the heat convection between the casting and the mold, and the heat conduction inside the casting and from the casting to the mold. In this paper, a formula of time step in simulation of solidification is derived, considering the heat radiation, convection and conduction based on the conservation of energy. The different heat transfer conditions between the conventional sand casting and the permanent mold casting are taken into account in this formula. The characteristics of heat transfer in the interior and surface of the casting are also considered. The numerical experiments show that this formula can avoid computational dispersion, and improve the computational efficiency by about 20% in the simulation of solidification process.
Asymptotic Derivation and Numerical Investigation of Time-Dependent Simplified Pn Equations
Olbrant, E; Frank, M; Seibold, B
2012-01-01
The steady-state simplified Pn (SPn) approximations to the linear Boltzmann equation have been proven to be asymptotically higher-order corrections to the diffusion equation in certain physical systems. In this paper, we present an asymptotic analysis for the time-dependent simplified Pn equations up to n = 3. Additionally, SPn equations of arbitrary order are derived in an ad hoc way. The resulting SPn equations are hyperbolic and differ from those investigated in a previous work by some of the authors. In two space dimensions, numerical calculations for the Pn and SPn equations are performed. We simulate neutron distributions of a moving rod and present results for a benchmark problem, known as the checkerboard problem. The SPn equations are demonstrated to yield significantly more accurate results than diffusion approximations. In addition, for sufficiently low values of n, they are shown to be more efficient than Pn models of comparable cost.
Bean, R; Bean, Rachel; Magueijo, Joao
2001-01-01
Quintessence scenarios provide a simple explanation for the observed acceleration of the Universe. Yet, explaining why acceleration did not start a long time ago remains a challenge. The idea that the transition from radiation to matter domination played a dynamical role in triggering acceleration has been put forward in various guises. We propose a simple dilaton-derived quintessence model in which temporary vacuum domination is naturally triggered by the radiation to matter transition. In this model Einstein's gravity is preserved but quintessence couples non-minimally to the cold dark matter, but not to ``visible'' matter. Such couplings have been attributed to the dilaton in the low-energy limit of string theory beyond tree level. We also show how a cosmological constant in the string frame translates into a quintessence-type of potential in the atomic frame.
Ghumare, Eshwar; Schrooten, Maarten; Vandenberghe, Rik; Dupont, Patrick
2015-08-01
Kalman filter approaches are widely applied to derive time varying effective connectivity from electroencephalographic (EEG) data. For multi-trial data, a classical Kalman filter (CKF) designed for the estimation of single trial data, can be implemented by trial-averaging the data or by averaging single trial estimates. A general linear Kalman filter (GLKF) provides an extension for multi-trial data. In this work, we studied the performance of the different Kalman filtering approaches for different values of signal-to-noise ratio (SNR), number of trials and number of EEG channels. We used a simulated model from which we calculated scalp recordings. From these recordings, we estimated cortical sources. Multivariate autoregressive model parameters and partial directed coherence was calculated for these estimated sources and compared with the ground-truth. The results showed an overall superior performance of GLKF except for low levels of SNR and number of trials.
NASA's ATM Technology Demonstration-1: Integrated Concept of Arrival Operations
Baxley, Brian T.; Swenson, Harry N.; Prevot, Thomas; Callantine, Todd J.
2012-01-01
This paper describes operations and procedures envisioned for NASA s Air Traffic Management (ATM) Technology Demonstration #1 (ATD-1). The ATD-1 Concept of Operations (ConOps) demonstration will integrate three NASA technologies to achieve high throughput, fuel-efficient arrival operations into busy terminal airspace. They are Traffic Management Advisor with Terminal Metering (TMA-TM) for precise time-based schedules to the runway and points within the terminal area, Controller-Managed Spacing (CMS) decision support tools for terminal controllers to better manage aircraft delay using speed control, and Flight deck Interval Management (FIM) avionics and flight crew procedures to conduct airborne spacing operations. The ATD-1 concept provides de-conflicted and efficient operations of multiple arrival streams of aircraft, passing through multiple merge points, from top-of-descent (TOD) to touchdown. It also enables aircraft to conduct Optimized Profile Descents (OPDs) from en route altitude to the runway, using primarily speed control to maintain separation and schedule. The ATD-1 project is currently addressing the challenges of integrating the three technologies, and implantation into an operational environment. Goals of the ATD-1 demonstration include increasing the throughput of high-density airports, reducing controller workload, increasing efficiency of arrival operations and the frequency of trajectory-based operations, and promoting aircraft ADS-B equipage.
Land use intensity trajectories on Amazonian pastures derived from Landsat time series
Rufin, Philippe; Müller, Hannes; Pflugmacher, Dirk; Hostert, Patrick
2015-09-01
Monitoring changes in land use intensity of grazing systems in the Amazon is an important prerequisite to study the complex political and socio-economic forces driving Amazonian deforestation. Remote sensing offers the potential to map pasture vegetation over large areas, but mapping pasture conditions consistently through time is not a trivial task because of seasonal changes associated with phenology and data gaps from clouds and cloud shadows. In this study, we tested spectral-temporal metrics derived from intra-annual Landsat time series to distinguish between grass-dominated and woody pastures. The abundance of woody vegetation on pastures is an indicator for management intensity, since the duration and intensity of land use steer secondary succession rates, apart from climate and soil conditions. We used the developed Landsat-based metrics to analyze pasture intensity trajectories between 1985 and 2012 in Novo Progresso, Brazil, finding that woody vegetation cover generally decreased after four to ten years of grazing activity. Pastures established in the 80s and early 90s showed a higher fraction of woody vegetation during their initial land use history than pastures established in the early 2000s. Historic intensity trajectories suggested a trend towards more intensive land use in the last decade, which aligns well with regional environmental policies and market dynamics. This study demonstrates the potential of dense Landsat time series to monitor land-use intensification on Amazonian pastures.
Foo, Jong Yong A; Wilson, Stephen J; Dakin, Carolyn; Williams, Gordon; Harris, Margaret-Anne; Cooper, David
2005-08-01
Pulse oximetry is commonly used as an arterial blood oxygen saturation (SaO2) measure. However, its other serial output, the photoplethysmography (PPG) signal, is not as well studied. Raw PPG signals can be used to estimate cardiovascular measures like pulse transit time (PTT) and possibly heart rate (HR). These timing-related measurements are heavily dependent on the minimal variability in phase delay of the PPG signals. Masimo SET Rad-9 and Novametrix Oxypleth oximeters were investigated for their PPG phase characteristics on nine healthy adults. To facilitate comparison, PPG signals were acquired from fingers on the same hand in a random fashion. Results showed that mean PTT variations acquired from the Masimo oximeter (37.89 ms) were much greater than the Novametrix (5.66 ms). Documented evidence suggests that 1 ms variation in PTT is equivalent to 1 mmHg change in blood pressure. Moreover, the PTT trend derived from the Masimo oximeter can be mistaken as obstructive sleep apnoeas based on the known criteria. HR comparison was evaluated against estimates attained from an electrocardiogram (ECG). Novametrix differed from ECG by 0.71+/-0.58% (pMasimo differed by 4.51+/-3.66% (p>0.05). Modern oximeters can be attractive for their improved SaO2 measurement. However, using raw PPG signals obtained directly from these oximeters for timing-related measurements warrants further investigations.
Analysis of electric vehicle's trip cost allowing late arrival
Leng, Jun-Qiang; Liu, Wei-Yi; Zhao, Lin
2017-05-01
In this paper, we use a car-following model to study each electric vehicle's trip cost and the total trip cost allowing late arrival. The numerical result show that the electricity cost has great effects on each commuter's trip cost and the total trip costs and that these effects are dependent on each commuter's time headway at the origin, but the electricity cost has no prominent impacts on the minimum value of total trip cost under each commuter's different time headway at the origin.
FORECASTING TOURIST ARRIVALS TO LANGKAWI ISLAND MALAYSIA
Directory of Open Access Journals (Sweden)
Kamarul Ariffin MANSOR
2015-06-01
Full Text Available Tourism is the act of travelling for a person or group of people from their own locality to a specific destination in a short term or long term period either for leisure or business purposes. Tourism is an important sector in the Malaysian economy where tourism development will lead to the positive economic development of the country and in general improve the quality of life for all citizens. Therefore, forecasting tourist arrivals with high accuracy becomes important since it may ensure the development and the readiness of all tourism related industries such as hotels, transportation, food and services industries and their best shape. This study focuses on tourist arrivals in Langkawi Island as one of the major tourist attractions situated in the northerly region of Peninsular Malaysia. Importantly, this paper attempts to measure and compare the performance of forecasting with Exponential Smoothing, ARIMA and ARFIMA models using the R software package.
Hardware-software complex of informing passengers of forecasted route transport arrival at stop
Pogrebnoy, V. Yu; Pushkarev, M. I.; Fadeev, A. S.
2017-02-01
The paper presents the hardware-software complex of informing the passengers of the forecasted route transport arrival. A client-server architecture of the forecasting information system is represented and an electronic information board prototype is described. The scheme of information transfer and processing, starting with receiving navigating telemetric data from a transport vehicle and up to the time of passenger public transport arrival at the stop, as well as representation of the information on the electronic board is illustrated and described. Methods and algorithms of determination of the transport vehicle current location in the city route network are considered in detail. The description of the proposed forecasting model of transport vehicle arrival time at the stop is given. The obtained result is applied in Tomsk for forecasting and displaying the arrival time information at the stops.
A NOVEL DIRECTION OF ARRIVAL ESTIMATOR
Institute of Scientific and Technical Information of China (English)
Shao Chao; Lu Guangyue; Bao Zheng
2004-01-01
A Direction Of Arrival(DOA) estimator based on the signal separation principle is introduced, and one of representative multidimensional estimators is established by introducing Matrix Operator projection signal steering Vector Excision(MOVE) operation. Thanks to Alternating Separation (AS) technique, the multidimensional problem is transformed into a series of one-dimensional optimal ones. Furthermore, an equivalent simplified implementation of the AS is obtained. Finally the definiteness and uniqueness of the estimator are analyzed.
Awarding Ceremony and New Arrivals of Blissliving
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
@@ The long expected Lan-Blisslivinghome Global Home Design Contest announced the winners on April 17 in Beijing.Young designers,Wang Yingying from Beijing and Qiang Xiaoning from Shanxi stood out from the crowd and won the first and second prize respectively.Malgorzata Czuchraj from Poland ranks the third.On the awarding ceremony,Blisslivinghome presented its autumn and winter new arrivals.
Target Localization Based on Angle of Arrivals
Institute of Scientific and Technical Information of China (English)
Yi-Chao Cao
2007-01-01
Mobile location using angle of arrival (AOA) measurements has received considerable attention. This paper presents an approximation of maximum likelihood estimator (MLE) for localizing a source based on AOA measurements. By introducing an intermediate variable, the nonlinear equations relating AOA estimates can be transformed into a set of equations which are linear in the unknown parameters. It is an approximate realization of the MLE. Simulations show that the proposed algorithm outperforms the previous contribution.
The first American magnet has arrived!
2003-01-01
On 21 January the first US-built LHC magnet arrived at CERN, after a journey of 6000 km by land and sea, an event hailed on both sides of the Atlantic. This 10-m long, 4.7-tonne dipole magnet was manufactured over a period of nine months by Brookhaven National Laboratory (BNL). Single-aperture magnets of this type will be installed on either side of the ALICE and LHCb experiments and will deviate the beams in order to provoke their interaction and subsequent separation. Brookhaven will be supplying 19 other dipoles for the insertion regions, including four of the same type as the one which has just arrived. «These magnets are based on a technology developed by Brookhaven Laboratory for its own RHIC accelerator,» explains Ranko Ostojic. LHC Project Leader Lyn Evans adds «our Brookhaven colleagues have done a fantastic job in completing the USA's first superconducting magnet for the LHC to specification and on schedule. Other deliveries will shortly be arriving from Brookhaven but also from Fermilab and the ...
Investigation on the coloured noise in GPS-derived position with time-varying seasonal signals
Gruszczynska, Marta; Klos, Anna; Bos, Machiel Simon; Bogusz, Janusz
2016-04-01
The seasonal signals in the GPS-derived time series arise from real geophysical signals related to tidal (residual) or non-tidal (loadings from atmosphere, ocean and continental hydrosphere, thermo elastic strain, etc.) effects and numerical artefacts including aliasing from mismodelling in short periods or repeatability of the GPS satellite constellation with respect to the Sun (draconitics). Singular Spectrum Analysis (SSA) is a method for investigation of nonlinear dynamics, suitable to either stationary or non-stationary data series without prior knowledge about their character. The aim of SSA is to mathematically decompose the original time series into a sum of slowly varying trend, seasonal oscillations and noise. In this presentation we will explore the ability of SSA to subtract the time-varying seasonal signals in GPS-derived North-East-Up topocentric components and show properties of coloured noise from residua. For this purpose we used data from globally distributed IGS (International GNSS Service) permanent stations processed by the JPL (Jet Propulsion Laboratory) in a PPP (Precise Point Positioning) mode. After introducing a threshold of 13 years, 264 stations left with a maximum length reaching 23 years. The data was initially pre-processed for outliers, offsets and gaps. The SSA was applied to pre-processed series to estimate the time-varying seasonal signals. We adopted a 3-years window as the optimal dimension of its size determined with the Akaike's Information Criteria (AIC) values. A Fisher-Snedecor test corrected for the presence of temporal correlation was used to determine the statistical significance of reconstructed components. This procedure showed that first four components describing annual and semi-annual signals, are significant at a 99.7% confidence level, which corresponds to 3-sigma criterion. We compared the non-parametric SSA approach with a commonly chosen parametric Least-Squares Estimation that assumes constant amplitudes and
Institute of Scientific and Technical Information of China (English)
刘运峰; 宋寿鹏; 马晓鲲; 王成
2012-01-01
在超声检测中,液位、压力、应力等参数的测量实际上转化为超声信号度越时间的测量,如何有效地提取超声回波信号的波至时刻成为能否准确测量的关键.在分析了连续复小波变换的模极大值包络提取和小波的奇异点检测理论的基础上,提出了一种新的超声信号波至检测函数,并选用复频域B样条和高斯函数为小波基,在MATLAB上对仿真信号及原始超声信号分析处理.实验结果表明,此检测函数在较低的信噪比条件下也可有效地提取到超声回波信号的波至时刻.%In ultrasonic testing,the measurement of the liquid level,the pressure, the stress and so on is in fact the measurement of the time-of-flight of the ultrasonic signal. Then how to implement the extraction of ultrasonic signal arrival time precisely becomes so important. Based on envelop extraction of continuous complex wavelet transform and the singularity point detection theory , a new arrival time detection function is shown. Emulation and the real acquired ultrasonic data were processed with MATLAB u-sing complex frequency B-spline and Gaussian function as wavelet. It is proved that the function has good detection effect even under low SNR condition.
Replacement policy in a system under shocks following a Markovian arrival process
Energy Technology Data Exchange (ETDEWEB)
Montoro-Cazorla, Delia [Department of Statistics and Operational Research, University of Jaen (Spain); Perez-Ocon, Rafael [Department of Statistics and Operational Research, University of Granada, Granada (Spain)], E-mail: rperezo@ugr.es; Carmen Segovia, Maria del [Departamento de Estadistica e I.O., University of Granada, Granada (Spain)
2009-02-15
We present a system subject to shocks that arrive following a Markovian arrival process. The system is minimally repaired. It is replaced when a certain number of shocks arrive. A general model where the replacements are governed by a discrete phase-type distribution is studied. For this system, the Markov process governing the system is constructed, and the interarrival times between replacements and the number of replacements are calculated. A special case of this system is when it can stand a prefixed number of shocks. For this new system, the same performance measures are calculated. The systems are considered in transient and stationary regime.
3D landslide motion from a UAV-derived time-series of morphological attributes
Valasia Peppa, Maria; Mills, Jon Philip; Moore, Philip; Miller, Pauline; Chambers, Jon
2017-04-01
Landslides are recognised as dynamic and significantly hazardous phenomena. Time-series observations can improve the understanding of a landslide's complex behaviour and aid assessment of its geometry and kinematics. Conventional quantification of landslide motion involves the installation of survey markers into the ground at discrete locations and periodic observations over time. However, such surveying is labour intensive, provides limited spatial resolution, is occasionally hazardous for steep terrain, or even impossible for inaccessible mountainous areas. The emergence of mini unmanned aerial vehicles (UAVs) equipped with off-the-shelf compact cameras, alongside the structure-from-motion (SfM) photogrammetric pipeline and modern pixel-based matching approaches, has expedited the automatic generation of high resolution digital elevation models (DEMs). Moreover, cross-correlation functions applied to finely co-registered consecutive orthomosaics and/or DEMs have been widely used to determine the displacement of moving features in an automated way, resulting in high spatial resolution motion vectors. This research focuses on estimating the 3D displacement field of an active slow moving earth-slide earth-flow landslide located in Lias mudrocks of North Yorkshire, UK, with the ultimate aim of assessing landslide deformation patterns. The landslide extends approximately 290 m E-W and 230 m N-S, with an average slope of 12˚ and 50 m elevation difference from N-S. Cross-correlation functions were applied to an eighteen-month duration, UAV-derived, time-series of morphological attributes in order to determine motion vectors for subsequent landslide analysis. A self-calibrating bundle adjustment was firstly incorporated into the SfM pipeline and utilised to process imagery acquired using a Panasonic Lumix DMC-LX5 compact camera from a mini fixed-wing Quest 300 UAV, with 2 m wingspan and maximum 5 kg payload. Data from six field campaigns were used to generate a DEM time
Solar wind driven empirical forecast models of the time derivative of the ground magnetic field
Directory of Open Access Journals (Sweden)
Wintoft Peter
2015-01-01
Full Text Available Empirical models are developed to provide 10–30-min forecasts of the magnitude of the time derivative of local horizontal ground geomagnetic field (|dBh/dt| over Europe. The models are driven by ACE solar wind data. A major part of the work has been devoted to the search and selection of datasets to support the model development. To simplify the problem, but at the same time capture sudden changes, 30-min maximum values of |dBh/dt| are forecast with a cadence of 1 min. Models are tested both with and without the use of ACE SWEPAM plasma data. It is shown that the models generally capture sudden increases in |dBh/dt| that are associated with sudden impulses (SI. The SI is the dominant disturbance source for geomagnetic latitudes below 50° N and with minor contribution from substorms. However, at occasions, large disturbances can be seen associated with geomagnetic pulsations. For higher latitudes longer lasting disturbances, associated with substorms, are generally also captured. It is also shown that the models using only solar wind magnetic field as input perform in most cases equally well as models with plasma data. The models have been verified using different approaches including the extremal dependence index which is suitable for rare events.
Wieser, R.
2016-10-01
The derivation of the time dependent Schrödinger equation with transversal and longitudinal relaxation, as the quantum mechanical analog of the classical Landau-Lifshitz-Bloch equation, has been described. Starting from the classical Landau-Lifshitz-Bloch equation the transition to quantum mechanics has been performed and the corresponding von-Neumann equation deduced. In a second step the time Schrödinger equation has been derived. Analytical proofs and computer simulations show the correctness and applicability of the derived Schrödinger equation.
Wieser, R
2016-10-05
The derivation of the time dependent Schrödinger equation with transversal and longitudinal relaxation, as the quantum mechanical analog of the classical Landau-Lifshitz-Bloch equation, has been described. Starting from the classical Landau-Lifshitz-Bloch equation the transition to quantum mechanics has been performed and the corresponding von-Neumann equation deduced. In a second step the time Schrödinger equation has been derived. Analytical proofs and computer simulations show the correctness and applicability of the derived Schrödinger equation.
Tourist Arrivals to Sabah by Using Fuzzy Forecasting
Tarmudi Zamali; Saibin Tammie Christy; Naharu Nasrah; Tamsin Nowyannie Willie D.
2014-01-01
The aim of this paper is to investigate the existing tourist trend arrival in Sabah based on fuzzy approach. It focuses on the latest 12 years (2002 – 2013) visitors arrival based on their nationality for forecasting purposes. Based on Sabah Tourism Board’s data, the tourist arrival continue to grow annually but with an inconsistent number of arrival. This can be seen from the trend of tourist arrival from 2011 to 2012. There is an increase in the number of arrival but only at 1.1 % compared ...
Zhou, Wen; Wang, Liangshu; Guan, Luping; Guo, Quanshi; Cui, Shuguo; Yu, Bo
2015-04-01
The accuracy of hypocenter location is the essential issue for microseismic monitoring, and is the basis for evaluating the effect of fracture. Although the signal obtained from a borehole monitoring system has a higher signal to noise ratio (SNR) than the surface system, a narrow monitoring aperture makes the location sensitive to noise and tends to be a misguided shape. In order to overcome this disadvantage and obtain a more accurate estimation of the source, we develop a ‘jointing method’, which combines the P-S phase arrival difference and P-wave arrival difference of each receiver pair (PSP) in the objective function. In the synthetic example, we compare the noise responses of three different location methods which are based on P-wave arrival time difference, P-S wave arrival time difference and the PSP method, respectively. This analysis shows that the P-wave arrival difference method is more sensitive to arrival time error than the others and the location results tend to be in a misleading line directed to the receivers. The P-S arrival difference method is more robust than the method using P-wave and its error distribution is perpendicular to the ray-path direction. The PSP method, as expected, is the most stable and accurate. When the P-S method and PSP method are applied to field data of a coal bed methane hydro-fracture process monitoring, the results indicate that the PSP method is preferable. The successful location with the PSP method proves that it is suitable for field data.
Chang, Cali; Demokritou, Philip; Shafer, Martin; Christiani, David
2013-01-01
Welding fume particles have been well studied in the past; however, most studies have examined welding fumes generated from machine models rather than actual exposures. Furthermore, the link between physicochemical and toxicological properties of welding fume particles has not been well understood. This study aims to investigate the physicochemical properties of particles derived during real time welding processes generated during actual welding processes and to assess the particle size specific toxicological properties. A compact cascade impactor (Harvard CCI) was stationed within the welding booth to sample particles by size. Size fractionated particles were extracted and used for both off-line physicochemical analysis and in vitro cellular toxicological characterization. Each size fraction was analyzed for ions, elemental compositions, and mass concentration. Furthermore, real time optical particle monitors (DustTrak™, TSI Inc., Shoreview, Minn.) were used in the same welding booth to collect real time PM2.5 particle number concentration data. The sampled particles were extracted from the polyurethane foam (PUF) impaction substrates using a previously developed and validated protocol, and used in a cellular assay to assess oxidative stress. By mass, welding aerosols were found to be in coarse (PM 2.5–10), and fine (PM 0.1–2.5) size ranges. Most of the water soluble (WS) metals presented higher concentrations in the coarse size range with some exceptions such as sodium, which presented elevated concentration in the PM 0.1 size range. In vitro data showed size specific dependency, with the fine and ultrafine size ranges having the highest reactive oxygen species (ROS) activity. Additionally, this study suggests a possible correlation between welders' experience, the welding procedure and equipment used and particles generated from welding fumes. Mass concentrations and total metal and water soluble metal concentrations of welding fume particles may be
Mumford, James
2013-01-01
Intellectual stalemate in the abortion debate can be traced in part to its being framed as a standoff between religion and secular philosophy. While the former is thought to generate a broadly 'pro-life' position, the latter is associated with more 'pro-choice' thinking. This essay attempts to break free of this framing by criticising the philosophy informing 'pro-choice' positions, but not by resorting immediately to religious arguments but rather by drawing upon a rival philosophical tradition--the movement within twentieth and twenty-first Continental philosophy which was and is phenomenology. A phenomenological approach to human 'emergence', and in particular an application of the framework Heidegger developed in Being and Time (1927), leads to a radical questioning of whether contemporary English-speaking beginning-of-life ethics have adequately taken into account the way human beings come forth in the world.
Ecosystems resilience to drought: indicators derived from time-series of Earth Observation data
Garcia, Monica; Fernández, Nestor; Delibes, Miguel
2013-04-01
Increasing our understanding of how ecosystems differ in their vulnerability to extreme climatic events such as drought is critical. Resilient ecosystems are capable to cope with climatic perturbations retaining the same essential function, structure and feedbacks. However, if the effect of a perturbation is amplified, abrupt shifts can occur such as in desertification processes. Empirical indicators of robustness and resilience to drought events could be developed from time series of Earth Observation (EO) data. So far, the information content of EO time series for monitoring ecosystem resilience has been underutilized, being mostly limited to detection of greening or rainfall use efficiency (RUE) trends at interannual time-scales. Detection of thresholds, shifts, extremes, and hysteresis processes is still in its infancy using EO data. Only recently some studies are starting to utilize this avenue of research using vegetation indices with some controversy due to the substitution of time by space. In drylands, where ecosystem functioning is largely controlled by rainfall, a key variable for monitoring is evapotranspiration as it connects the energy, water and carbon cycles. It can be estimated using EO data using a surface energy balance approach. In this work we propose the use of new empirical indicators of resilience to drought derived from EO time series. They are extracted from analyses of lagged cross-correlations between rainfall and evapotranspiration anomalies at several time-steps. This allows elucidating as well if an observed extreme ecological response can be attributed to a climate extreme. Additionally, increases in autocorrelation have been proposed to detect losses of resilience or changes in recovery capacity from a perturbation. Our objective was to compare rates of recovery from drought of different ecosystems in the natural park of Doñana (Spain) composed of wetlands, pine forest, shrublands with and without access to groundwater. The
Sinking Chao Phraya delta plain, Thailand, derived from SAR interferometry time series analysis
Tanaka, A.; Mio, A.; Saito, Y.
2013-12-01
The Bangkok Metropolitan region and its surrounding provinces are located in a low-lying delta plain of the Chao Phraya River. Extensive groundwater use from the late 1950s has caused the decline of groundwater levels in the aquifers and Holocene clay compaction beneath the Bangkok Region, resulting in significant subsidence of the ground. This ground deformation has been monitored using leveling surveys since 1978, and differential InSAR (Interferometric Synthetic Aperture Radar) analysis. It shows that the Bangkok Metropolitan region is subsiding at a rate of about 20 mm/year during the recent years due to law-limited groundwater pumping, although the highest subsidence rate as high as 120 mm/year was recorded in 1981. The subsidence rate in the Bangkok area has significantly decreased since the late 1980s; however, the affected area has spread out to the surrounding areas. The maximum subsidence rate up to 30 mm/year occurred in the outlying southeast and southwest coastal zones in 2002. In this study, we apply a SAR interferometry time series analysis to monitor ground deformations in the lower Chao Phraya delta plain (Lower Central Plain), Thailand, using ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band SAR) data acquired between July 2007 and September 2010. We derive a single reference time series interferogram from the stacking of unwrapped phases under the assumptions that those phases are smoothly and continuously connected, and apply a smoothness-constrained inversion algorithm that optimizes the displacement from the phase unwrapping of multitemporal differential SAR interferograms. The SAR interferometry time series analysis succeeds to monitor the incremental line-of-sight (LOS)-change between SAR scene acquisitions. LOS displacements are converted to vertical displacements, based on the assumption that the ground displacement in this area occurs only in the vertical directions. This reveals an overall pattern of subsidence
Lee, Yong Woo; Lee, Duck Joo
2014-12-01
Kirchhoff's formula for the convective wave equation is derived using the generalized function theory. The generalized convective wave equation for a stationary surface is obtained, and the integral formulation, the convective Kirchhoff's formula, is derived. The formula has a similar form to the classical Kirchhoff's formula, but an additional term appears due to a moving medium effect. For convenience, the additional term is manipulated to a final form as the classical Kirchhoff's formula. The frequency domain boundary integral can be obtained from the current time domain boundary integral form. The derived formula is verified by comparison with the analytic solution of source in the uniform flow. The formula is also utilized as a boundary integral equation. Time domain boundary element method (BEM) analysis using the boundary integral equation is conducted, and the results show good agreement with the analytical solution. The formula derived here can be useful for sound radiation and scattering by arbitrary bodies in a moving medium in the time domain.
GMTI Direction of Arrival Measurements from Multiple Phase Centers.
Energy Technology Data Exchange (ETDEWEB)
Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bickel, Douglas L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-03-01
Ground Moving Target Indicator (GMTI) radar attempts to detect and locate targets with unknown motion. Very slow-moving targets are difficult to locate in the presence of surrounding clutter. This necessitates multiple antenna phase centers (or equivalent) to offer independent Direction of Arrival (DOA) measurements. DOA accuracy and precision generally remains dependent on target Signal-to-Noise Ratio (SNR), Clutter-toNoise Ratio (CNR), scene topography, interfering signals, and a number of antenna parameters. This is true even for adaptive techniques like Space-Time-AdaptiveProcessing (STAP) algorithms.
Stare and chase of space debris targets using real-time derived pointing data
Steindorfer, Michael A.; Kirchner, Georg; Koidl, Franz; Wang, Peiyuan; Antón, Alfredo; Fernández Sánchez, Jaime; Merz, Klaus
2017-09-01
We successfully demonstrate Stare & Chase: Space debris laser ranging to uncooperative targets has been achieved without a priori knowledge of any orbital information. An analog astronomy CCD with a standard objective, piggyback mounted on our 50 cm Graz SLR receive telescope, 'stares' into the sky in a fixed direction. The CCD records the stellar background within a field of view of approx. 7°. From the stellar X/Y positions on the sensor a plate solving algorithm determines the pointing data of the image center with an accuracy of approx. 15 arc seconds. If a sunlit target passes through this field of view, its equatorial coordinates are calculated, stored and a Consolidated Prediction Format (CPF) file is created in near real time. The derived CPF data is used to start laser ranging ('chase' the object) within the same pass to retrieve highly accurate distance information. A comparison of Stare & Chase CPFs with standard TLE predictions shows the possibilities and limits of this method.
Duvall, Thomas L.; Hanasoge, Shravan M.
2012-01-01
With large separations (10-24 deg heliocentric), it has proven possible to cleanly separate the horizontal and vertical components of supergranular flow with time-distance helioseismology. These measurements require very broad filters in the k-$\\omega$ power spectrum as apparently supergranulation scatters waves over a large area of the power spectrum. By picking locations of supergranulation as peaks in the horizontal divergence signal derived from f-mode waves, it is possible to simultaneously obtain average properties of supergranules and a high signal/noise ratio by averaging over many cells. By comparing ray-theory forward modeling with HMI measurements, an average supergranule model with a peak upflow of 240 m/s at cell center at a depth of 2.3 Mm and a peak horizontal outflow of 700 m/s at a depth of 1.6 Mm. This upflow is a factor of 20 larger than the measured photospheric upflow. These results may not be consistent with earlier measurements using much shorter separations (<5 deg heliocentric). With a 30 Mm horizontal extent and a few Mm in depth, the cells might be characterized as thick pancakes.
Gorpas, Dimitris; Ma, Dinglong; Bec, Julien; Yankelevich, Diego R; Marcu, Laura
2016-08-01
Fiber based fluorescence lifetime imaging has shown great potential for intraoperative diagnosis and guidance of surgical procedures. Here we describe a novel method addressing a significant challenge for the practical implementation of this technique, i.e., the real-time display of the quantified biochemical or functional tissue properties superimposed on the interrogated area. Specifically, an aiming beam (450 nm) generated by a continuous-wave laser beam was merged with the pulsed fluorescence excitation light in a single delivery/collection fiber and then imaged and segmented using a color-based algorithm. We demonstrate that this approach enables continuous delineation of the interrogated location and dynamic augmentation of the acquired frames with the corresponding fluorescence decay parameters. The method was evaluated on a fluorescence phantom and fresh tissue samples. Current results demonstrate that 34 frames per second can be achieved for augmenting videos of 640 × 512 pixels resolution. Also we show that the spatial resolution of the fluorescence lifetime map depends on the tissue optical properties, the scanning speed, and the frame rate. The dice similarity coefficient between the fluorescence phantom and the reconstructed maps was estimated to be as high as 93%. The reported method could become a valuable tool for augmenting the surgeon's field of view with diagnostic information derived from the analysis of fluorescence lifetime data in real-time using handheld, automated, or endoscopic scanning systems. Current method provides also a means for maintaining the tissue light exposure within safety limits. This study provides a framework for using an aiming beam with other point spectroscopy applications.
Directory of Open Access Journals (Sweden)
Emily C. O'Brien
2011-01-01
Full Text Available Background. Recent studies report that acute stroke patients who present to the hospital on weekends have higher rates of 28-day mortality than similar patients who arrive during the week. However, how this association is related to clinical presentation and stroke type has not been systematically investigated. Methods and Results. We examined the association between day of arrival and 28-day mortality in 929 validated stroke events in the ARIC cohort from 1987–2004. Weekend arrival was defined as any arrival time from midnight Friday until midnight Sunday. Mortality was defined as all-cause fatal events from the day of arrival through the 28th day of followup. The presence or absence of thirteen stroke signs and symptoms were obtained through medical record review for each event. Binomial logistic regression was used to estimate odds ratios and 95% confidence intervals (OR; 95% CI for the association between weekend arrival and 28-day mortality for all stroke events and for stroke subtypes. The overall risk of 28-day mortality was 9.6% for weekday strokes and 10.1% for weekend strokes. In models controlling for patient demographics, clinical risk factors, and event year, weekend arrival was not associated with 28-day mortality (0.87; 0.51, 1.50. When stratified by stroke type, weekend arrival was not associated with increased odds of mortality for ischemic (1.17, 0.62, 2.23 or hemorrhagic (0.37; 0.11, 1.26 stroke patients. Conclusions. Presence or absence of thirteen signs and symptoms was similar for weekday patients and weekend patients when stratified by stroke type. Weekend arrival was not associated with 28-day all-cause mortality or differences in symptom presentation for strokes in this cohort.
Automated Conflict Resolution, Arrival Management and Weather Avoidance for ATM
Erzberger, H.; Lauderdale, Todd A.; Chu, Yung-Cheng
2010-01-01
The paper describes a unified solution to three types of separation assurance problems that occur in en-route airspace: separation conflicts, arrival sequencing, and weather-cell avoidance. Algorithms for solving these problems play a key role in the design of future air traffic management systems such as NextGen. Because these problems can arise simultaneously in any combination, it is necessary to develop integrated algorithms for solving them. A unified and comprehensive solution to these problems provides the foundation for a future air traffic management system that requires a high level of automation in separation assurance. The paper describes the three algorithms developed for solving each problem and then shows how they are used sequentially to solve any combination of these problems. The first algorithm resolves loss-of-separation conflicts and is an evolution of an algorithm described in an earlier paper. The new version generates multiple resolutions for each conflict and then selects the one giving the least delay. Two new algorithms, one for sequencing and merging of arrival traffic, referred to as the Arrival Manager, and the other for weather-cell avoidance are the major focus of the paper. Because these three problems constitute a substantial fraction of the workload of en-route controllers, integrated algorithms to solve them is a basic requirement for automated separation assurance. The paper also reviews the Advanced Airspace Concept, a proposed design for a ground-based system that postulates redundant systems for separation assurance in order to achieve both high levels of safety and airspace capacity. It is proposed that automated separation assurance be introduced operationally in several steps, each step reducing controller workload further while increasing airspace capacity. A fast time simulation was used to determine performance statistics of the algorithm at up to 3 times current traffic levels.
Direction of Arrival Estimation of Wide-Band Emitters
Hojati, Shahram
Most published algorithms for DOA (Direction of Arrival) estimation of incoming signals by spatially dispersed electromagnetic or acoustic sources rely on the narrow -band approximation. This approach is inadequate from at least two standpoints. First, the approximation breaks down in many practical situation of interest; and, second, it inhibits the exploitation of intrinsic degrees of freedom of wide-band emitters to achieve additional improvements in angular resolution. In this dissertation the direction of arrival estimation problem is examined without employing the customary narrow-band restriction. A class of algorithms that has been successfully employed for DOA estimation of narrow-band signals exploits the eigenstructure of the array correlation matrix. Although they are sub-optimum, these algorithms enjoy substantial computational advantages over the optimum maximum likelihood approaches. It is shown that the frequency domain representation of the array output leads to a spectral coherence matrix that exhibits an eigenstructure similar to the correlation matrix used under the narrow-band approximation. As a consequence, narrow-band eigenbased algorithms can be adopted to DOA estimation without restrictions on signal bandwidth. The Spectral Coherence Technique (SCT) is applied in conjunction with the MUSIC, the Root-Music and a modified form of the Pisarenko algorithms to DOA estimation of wide -band emitters using linear arrays. Simulation indicate that all three algorithms afford comparable performance: the variance of the angle of arrival estimate decreases approximately inversely with the signal time bandwidth product. They differ, however, with regard to computational efficiency. In particular, the wide-band version of the algorithm MUSIC requires substantially more processing time than either the Pisarenko or the Root-Music algorithms. These algorithms also yield comparable performance to an alternative approach using frequency segmentation (Wi
Detection and Estimation of Arrivals in Room Impulse Responses by Greedy Sparse Approximation
DEFF Research Database (Denmark)
Sturm, Bob L.; Defrance, Guillaume
2010-01-01
We investigate the use of greedy sparse approximation for facilitating the time-domain analysis of room impulse responses (RIRs), specifically locating the times and amplitudes of arrivals to not long after the upper bound of the ``mixing time,'' i.e., the time after which there exists in theory...
Angle-of-Arrival Assisted GNSS Collaborative Positioning.
Huang, Bin; Yao, Zheng; Cui, Xiaowei; Lu, Mingquan
2016-06-20
For outdoor and global navigation satellite system (GNSS) challenged scenarios, collaborative positioning algorithms are proposed to fuse information from GNSS satellites and terrestrial wireless systems. This paper derives the Cramer-Rao lower bound (CRLB) and algorithms for the angle-of-arrival (AOA)-assisted GNSS collaborative positioning. Based on the CRLB model and collaborative positioning algorithms, theoretical analysis are performed to specify the effects of various factors on the accuracy of collaborative positioning, including the number of users, their distribution and AOA measurements accuracy. Besides, the influences of the relative location of the collaborative users are also discussed in order to choose appropriate neighboring users, which is in favor of reducing computational complexity. Simulations and actual experiment are carried out with several GNSS receivers in different scenarios, and the results are consistent with theoretical analysis.
Smith, E. J.; Vonken, E. -J.; Meijer, F. J. A.; Dankbaar, J. W.; Horsch, A. D.; van Ginneken, B.; Velthuis, B.; van der Schaaf, I.; Prokop, M.
2015-01-01
BACKGROUND AND PURPOSE: Timing-invariant (or delay-insensitive) CT angiography derived from CT perfusion data may obviate a separate cranial CTA in acute stroke, thus enhancing patient safety by reducing total examination time, radiation dose, and volume of contrast material. We assessed the diagnos
Derivation of the energy-momentum and Klein-Gordon equations from El Naschie's complex time
Energy Technology Data Exchange (ETDEWEB)
Di Sigalotti, Leonardo G. [Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas, IVIC, Apartado 20632, Caracas 1020A (Venezuela, Bolivarian Republic of)], E-mail: leonardo.sigalotti@gmail.com; Mejias, Antonio [Instituto Universitario Tecnologico de Ejido, IUTE, Avenida 25 de Noviembre, Ejido 5251, Estado Merida (Venezuela, Bolivarian Republic of)], E-mail: antoniojmm@cantv.net; Trujillo, Leonardo [Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas, IVIC, Apartado 20632, Caracas 1020A (Venezuela, Bolivarian Republic of)], E-mail: leo@ivic.ve
2009-12-15
In a previous note, we have provided a formal derivation of the transverse Doppler shift of special relativity from the generalization of El Naschie's complex time. Here, we show that the relativistic energy-momentum equation, and hence the Klein-Gordon equation, are also natural consequences of the complex time generalization.
Deriving Daily Time Series Evapotranspiration, Evaporation and Transpiration Maps With Landsat Data
Paul, G.; Gowda, P. H.; Marek, T.; Xiao, X.; Basara, J. B.
2014-12-01
Mapping high resolution evapotranspiration (ET) over large region at daily time step is complex and computationally intensive. Utility of high resolution daily ET maps are large ranging from crop water management to watershed management. The aim of this work is to generate daily time series (10 years) ET and its components vegetation transpiration (T) and soil water evaporation (E) maps using Landsat 5 satellite data for Southern Great Plains forage-rangeland-winter wheat production system in Oklahoma (OK). Framework for generating these products included the two source energy balance (TSEB) algorithm and other important features were: (a) atmospheric correction algorithm; (b) spatially interpolated weather inputs; (c) functions for varying Priestley-Taylor coefficient; and (d) ET, E and T extrapolating algorithm utilizing reference ET. An extensive network of 140 weather stations managed by Oklahoma Mesonet was utilized to generate spatially interpolated inputs of air temperature, relative humidity, wind speed, solar radiation, pressure, and reference ET. Validation of the ET maps were done against eddy covariance data from two grassland sites at El Reno, OK suggested good performance (Table 1). Figure 1 illustrates a daily ET map for a very small subset of 18thJuly 2006 ET map, where difference in ET among different land uses such as the irrigated cropland, vegetation along drainage, and grassland is very distinct. Results indicated that the proposed ET mapping framework is suitable for deriving high resolution time series daily ET maps at regional scale with Landsat Thematic Mapper data. . Table 1: Daily actual ET performance statistics for two grassland locations at El Reno OK for year 2005 . Management Type Mean (obs) (mm d-1) Mean (est) (mm d-1) MBE (mm d-1) % MBE (%) RMSE (mm d-1) RMSE (%) MAE (mm d-1) MAPD (%) NSE R2 Control 2.2 1.8 -0.43 -19.4 0.87 38.9 0.65 29.5 0.71 0.79 Burnt 2.0 1.8 -0.15 -7.7 0.80 39.8 0.62 30.7 0.73 0.77
First SCT Barrel arrives at CERN
Apsimon, R
Mid-January saw the arrival at CERN of Barrel #3, the first of four SCT barrels. The barrels are formed as low-mass cylinders of carbon fibre skins on a honeycomb carbon core. They are manufactured in industry and then have all the final precision supports added and the final geometric metrology carried out at Geneva University. Barrel #3, complete with its 384 silicon detector modules, arrived by road from Oxford University in England where the modules were mounted using a purpose-built robot. The modules had been selected from the output of all four barrel module building clusters (in Japan, Scandinavia, USA and the UK). Since Barrel #3 will be exposed to high radiation levels within the tracker volume, these modules, representing over half a million readout channels, have been extensively tested at their operational temperature of around -25 degrees Celcius and at voltages of up to 500V. The dangers of shipping such a fragile component of ATLAS were apparent to all and considerable attention was focused...
A key component of the Globe arrives
2003-01-01
The first component of the Palais de l'Equilibre arrived at CERN last week. Renamed the Globe of Innovation, this elegant wooden sphere will be inaugurated in October 2004. The convoy transporting the first component of the Palais de l'Equilibre, the keystone of the famous wooden globe, arrived at CERN on the night of 28th August in the middle of a violent storm and dramatic flashes of lightning. Erected in Neuchâtel last year for the EXPO.02 exhibition, the Palais de l'Equilibre was a gift to the Laboratory from the Swiss Confederation (see Bulletin 25/2003). The gift of the structure and 4 million Swiss francs, together with help from the Swiss army for the reassembly work, received the final approval of the Swiss Federal Council on 20th August 2003. Renamed the Globe of Innovation, the 27-metre-high sphere measuring 40 metres in diameter will house the Laboratory's new exhibition centre in 2005. The keystone, known as the "central vertex", is a crown measuring 6.5 m in diameter and 4.5 m high, located a...
LHCb Calorimeter modules arrive at CERN
2002-01-01
Two of the three components of the LHCb Calorimeter system have started to arrive from Russia. Members of the LHCb Calorimeter group with the ECAL and HCAL modules that have just arrived at CERN. The first two of the 56 Hadron Calorimeter (HCAL) modules and 1200 of the 3300 modules of the Electromagnetic Calorimeter (ECAL) have reached CERN from Russia. The third part of the system, the Preshower detector, is still being prepared in Russia. The calorimeter system identifies and triggers on high-energy particles, namely electrons, hadrons and photons by measuring their positions and energies. The HCAL is going to be a pure trigger device. The ECAL will also be used in the triggering, but in addition it will reconstruct neutral pions and photons from B meson decays. One of the major aims of the LHCb experiment is to study CP violation through B meson decays including Bs mesons with high statistics in different decay modes. CP violation (violation of charge and parity) is necessary to explain why the Universe...
Heston, Steven L.; Nandi, Saikat
1999-01-01
This paper develops a discrete-time two-factor model of interest rates with analytical solutions for bonds and many interest rate derivatives when the volatility of the short rate follows a GARCH process that can be correlated with the level of the short rate itself. Besides bond and bond futures, the model yields analytical solutions for prices of European options on discount bonds (and futures) as well as other interest rate derivatives such as caps, floors, average rate options, yield curv...
A Contract That Manages Itself: The Time Has Arrived
2015-02-01
unlike a relational database that stores and retrieves data items, an ontologi - cal database system brings understanding into the realm of data queries...tological database will solve this problem. In the intelligent contract paradigm, an ontological da- tabase will be developed to link data from the...reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of
Original Research Factors associated with hospital arrival time after ...
African Journals Online (AJOL)
Correspondence: Ms Theodora M. Chikwanha (middychiky@yahoo.co.uk). Introduction ..... more than 83,000 children and youths under 20 years being affected annually in both ... Overweight. Unfit ... to be both a physical and social condition, and consequently .... healthcare workers be harnessed through activities such as.
Arriving before starting – About time travel and warp drive
Herrmann, Kay
2016-01-01
Zeitreisen und Reisen mit Überlichtgeschwindigkeit sind zwei Menschheitsträume; sie beflügeln die Fantasie und bieten Stoff für skurrile Geschichten. Eine Arbeit zum Thema „Zeitreisen und Reisen mit Überlichtgeschwindigkeit“ zwingt zu einer Auseinandersetzung mit dem Begriff der „Zeit“. Die Vielschichtigkeit und der antinomische Charakter dieses Begriffes machen es schwer, „Zeit“ genauer zu fassen. Zeit tritt uns entgegen als Form der Wahrnehmung in ihrer zutiefst subjektiven Seite, als b...
Time Delay of Arrival Location Assessment Using Four Satellites.
1984-12-01
positioning system for the US Navy in the early 1960"s (4:40). In the early 1970’s, there were two competing concepts, TIMATION (US Navy) and Program 621B (US...matrix algbra , the determinant is zero, which implies that I the matrix is singular. Because the matrix is singular, no inverse for matrix A exist
A generic probability based model to derive regional patterns of crops in time and space
Wattenbach, Martin; Luedtke, Stefan; Redweik, Richard; van Oijen, Marcel; Balkovic, Juraj; Reinds, Gert Jan
2015-04-01
Croplands are not only the key to human food supply, they also change the biophysical and biogeochemical properties of the land surface leading to changes in the water cycle, energy portioning, they influence soil erosion and substantially contribute to the amount of greenhouse gases entering the atmosphere. The effects of croplands on the environment depend on the type of crop and the associated management which both are related to the site conditions, economic boundary settings as well as preferences of individual farmers. The method described here is designed to predict the most probable crop to appear at a given location and time. The method uses statistical crop area information on NUTS2 level from EUROSTAT and the Common Agricultural Policy Regionalized Impact Model (CAPRI) as observation. These crops are then spatially disaggregated to the 1 x 1 km grid scale within the region, using the assumption that the probability of a crop appearing at a given location and a given year depends on a) the suitability of the land for the cultivation of the crop derived from the MARS Crop Yield Forecast System (MCYFS) and b) expert knowledge of agricultural practices. The latter includes knowledge concerning the feasibility of one crop following another (e.g. a late-maturing crop might leave too little time for the establishment of a winter cereal crop) and the need to combat weed infestations or crop diseases. The model is implemented in R and PostGIS. The quality of the generated crop sequences per grid cell is evaluated on the basis of the given statistics reported by the joint EU/CAPRI database. The assessment is given on NUTS2 level using per cent bias as a measure with a threshold of 15% as minimum quality. The results clearly indicates that crops with a large relative share within the administrative unit are not as error prone as crops that allocate only minor parts of the unit. However, still roughly 40% show an absolute per cent bias above the 15% threshold. This
Libertino, Andrea; Claps, Pierluigi; Sharma, Ashish; Lakshmi, Venkat
2016-04-01
Severe rainfall events are quite common in the coastal areas of the Mediterranean basin during autumn season, despite its generally mild climate. Very often meteorological conditions responsible for these kinds of events are quasi-stationary convective systems, characterized by very localized development, hard to detect with traditional rain gauge networks. In order to improve prediction and management capabilities, progress must be made in understanding the mechanism that govern the development of these kind of precipitation systems at the different scales. Rainfall product from the Tropical Rainfall Measuring Mission (TRMM) are commonly adopted in different branches of the environmental sciences due to the high spatio-temporal resolution and to the quasi-global nature of the data. Building upon the success of TRMM, NASA and JAXA deployed the GPM Core Observatory that, after just two years of activity, seems to allow for great improvement in the accuracy of rainfall products. We developed a methodology aimed at exploiting the timing information derived from high-resolution remote sensing products to analyze the characteristic of severe rainfall systems in the Mediterranean basin. The spatial analysis from satellite, combined with the historical information from the rain gauge network, allows us deepening the knowledge of the spatial extension of extreme rainfall phenomena. All those information, merged together in a hierarchical framework, lead to the definition of Intensity-Duration-Frequency curves "informed" on the nature of the events for each location of the domain, without the need to adopt classical interpolation techniques, unable to represent the complexity of the rainfall systems. The case study refers to a database of daily rainfall measurements extracted from the NOAA GHCN-Daily dataset, recorded during the 20th century by 700 rain gauges distributed in the Mediterranean basin. TRMM and GPM images are used to calibrate the event timing over the
Colaninno, R C; Wu, C -C
2013-01-01
We investigate the performance of six methods for predicting the CME time of arrival (ToA) and velocity at Earth using a sample of nine Earth-impacting CMEs between May 2010 and June 2011. The CMEs were tracked continuously from the Sun to near Earth in multi-viewpoint imaging data from STEREO SECCHI and SOHO LASCO. We use the Graduate Cylindrical Shell (GCS) model to estimate the three-dimensional direction and height of the CMEs in every image out to $\\sim$200 R$_\\odot$. We fit the derived three-dimensional (deprojected) height and time data with six different methods to extrapolate the CME ToA and velocity at Earth. We compare the fitting results with the in situ data from the WIND spacecraft. We find that a simple linear fit after a height of 50$R_\\odot$ gives the best ToA with a total error $\\pm$13 hours. For seven (78%) of the CMEs, we are able to predict the ToA to within $\\pm$6 hours. These results are a full day improvement over past CME arrival time methods that only used SOHO LASCO data. We conclud...
Directory of Open Access Journals (Sweden)
Rafael Morales
2014-05-01
Full Text Available Time derivative estimation of signals plays a very important role in several fields, such as signal processing and control engineering, just to name a few of them. For that purpose, a non-asymptotic algebraic procedure for the approximate estimation of the system states is used in this work. The method is based on results from differential algebra and furnishes some general formulae for the time derivatives of a measurable signal in which two algebraic derivative estimators run simultaneously, but in an overlapping fashion. The algebraic derivative algorithm presented in this paper is computed online and in real-time, offering high robustness properties with regard to corrupting noises, versatility and ease of implementation. Besides, in this work, we introduce a novel architecture to accelerate this algebraic derivative estimator using reconfigurable logic. The core of the algorithm is implemented in an FPGA, improving the speed of the system and achieving real-time performance. Finally, this work proposes a low-cost platform for the integration of hardware in the loop in MATLAB.
Svedhem, Hakan; Vago, Jorge L.; ExoMars Team
2016-10-01
The Trace Gas Orbiter (TGO) and the Schiaparelli Entry, descent and landing Demonstrator Model (EDM) will arrive at Mars on 19 October 2016. The TGO and the EDM are part of the first step of the ExoMars Programme. They will be followed by a Rover and a long lived Surface Platform to be launched in 2020.The EDM is attached to the TGO for the full duration of the cruise to Mars and will be separated three days before arrival at Mars. After separation the TGO will perform a deflection manoeuvre and, on 19 October (during the EDM landing), enter into a highly elliptical near equatorial orbit. TGO will remain in this parking orbit until January 2017, when the orbital plane inclination will be changed to 74 degrees and aerobraking to the final 400 km near circular orbit will start. The final operational orbit is expected to be reached at the end of 2017.The TGO scientific payload consists of four instruments. These are: ACS and NOMAD, both infrared spectrometers for atmospheric measurements in solar occultation mode and in nadir mode, CASSIS, a multichannel camera with stereo imaging capability, and FREND, an epithermal neutron detector for search of subsurface hydrogen. The mass of the TGO is 3700 kg, including fuel. The EDM, with a mass of 600 kg, is mounted on top of the TGO as seen in its launch configuration. The main objective of the EDM is to demonstrate the capability of performing a safe entry, descent and landing on the surface, but it does carry a descent camera and a small battery powered meteorological package that may operate for a few days on the surface.The ExoMars programme is a joint activity by the European Space Agency(ESA) and ROSCOSMOS, Russia. ESA is providing the TGO spacecraft and Schiaparelli (EDM) and two of the TGO instruments and ROSCOSMOS is providing the launcher and the other two TGO instruments. After the arrival of the ExoMars 2020 mission at the surface of Mars, the TGO will handle the communication between the Earth and the Rover and
Yu, Pao-Shan; Yang, Tao-Chang; Chen, Szu-Yin; Kuo, Chen-Min; Tseng, Hung-Wei
2017-09-01
This study aims to compare two machine learning techniques, random forests (RF) and support vector machine (SVM), for real-time radar-derived rainfall forecasting. The real-time radar-derived rainfall forecasting models use the present grid-based radar-derived rainfall as the output variable and use antecedent grid-based radar-derived rainfall, grid position (longitude and latitude) and elevation as the input variables to forecast 1- to 3-h ahead rainfalls for all grids in a catchment. Grid-based radar-derived rainfalls of six typhoon events during 2012-2015 in three reservoir catchments of Taiwan are collected for model training and verifying. Two kinds of forecasting models are constructed and compared, which are single-mode forecasting model (SMFM) and multiple-mode forecasting model (MMFM) based on RF and SVM. The SMFM uses the same model for 1- to 3-h ahead rainfall forecasting; the MMFM uses three different models for 1- to 3-h ahead forecasting. According to forecasting performances, it reveals that the SMFMs give better performances than MMFMs and both SVM-based and RF-based SMFMs show satisfactory performances for 1-h ahead forecasting. However, for 2- and 3-h ahead forecasting, it is found that the RF-based SMFM underestimates the observed radar-derived rainfalls in most cases and the SVM-based SMFM can give better performances than RF-based SMFM.
Alimohammadi, Shahrouz; Cavaglieri, Daniele; Beyhaghi, Pooriya; Bewley, Thomas R.
2016-11-01
This work applies a recently developed Derivative-free optimization algorithm to derive a new mixed implicit-explicit (IMEX) time integration scheme for Computational Fluid Dynamics (CFD) simulations. This algorithm allows imposing a specified order of accuracy for the time integration and other important stability properties in the form of nonlinear constraints within the optimization problem. In this procedure, the coefficients of the IMEX scheme should satisfy a set of constraints simultaneously. Therefore, the optimization process, at each iteration, estimates the location of the optimal coefficients using a set of global surrogates, for both the objective and constraint functions, as well as a model of the uncertainty function of these surrogates based on the concept of Delaunay triangulation. This procedure has been proven to converge to the global minimum of the constrained optimization problem provided the constraints and objective functions are twice differentiable. As a result, a new third-order, low-storage IMEX Runge-Kutta time integration scheme is obtained with remarkably fast convergence. Numerical tests are then performed leveraging the turbulent channel flow simulations to validate the theoretical order of accuracy and stability properties of the new scheme.
Transient and Stationary Losses in a Finite-Buffer Queue with Batch Arrivals
Directory of Open Access Journals (Sweden)
Andrzej Chydzinski
2012-01-01
Full Text Available We present an analysis of the number of losses, caused by the buffer overflows, in a finite-buffer queue with batch arrivals and autocorrelated interarrival times. Using the batch Markovian arrival process, the formulas for the average number of losses in a finite time interval and the stationary loss ratio are shown. In addition, several numerical examples are presented, including illustrations of the dependence of the number of losses on the average batch size, buffer size, system load, autocorrelation structure, and time.
Anticipating arrival: is the tau margin a specious theory?
Wann, J P
1996-08-01
A critical review is presented of previous studies that have examined the use of the tau margin (tau m) in the temporal judgment of arrival in natural contexts. This body of evidence is frequently cited as providing strong support for the use of Tau m for interceptive timing. Critical flaws are demonstrated in either the analysis or interpretation of many of these studies. It is suggested that temporal control in a number of these experiments could have been effected using a relative distance estimate (zeta ratio). Results are also presented and discussed that conflict with the tau m control hypothesis. It is concluded that although the tau m hypothesis provides an appealing account of interceptive timing, its broad acceptance is unwarranted on the evidence available.
Time Study of Harvesting Equipment Using GPS-Derived Positional Data
Tim McDonald
1999-01-01
The objectives in this study were to develop and test a data analysis system for calculating machine productivity from GPS-derived positional information alone. A technique was used where positions were `filtered' initially to locate specific events that were independent of what actually traveled the path, then these events were combined using user-specified rules...
Derivation of factors to estimate daily milk yield from one milking of cows milked three times daily
The objective was to derive factors to predict daily milk yield when milk is sampled once per d for cows milked three times (3x) per d. Milk weights for all three milkings were recorded automatically by 8 herds and collected by Dairy Herd Improvement supervisors on test-day. Following edits, 196,725...
The objective was to derive factors to predict daily yield when milk weights are recorded once when cows are milked twice (2x) or once or twice when cows are milked thrice (3x) per d. Data was from herds enrolled in DHI and automatically recording milking weights and times. Following edits, 83,690...
L.A. van Vianen (Lars); A.F. Gabor (Adriana); J.C.W. van Ommeren (Jan-Kees)
2014-01-01
textabstractIn this article we give a new derivation for the waiting time distributions in an M/M/c queue with multiple priorities and a common service rate by using elementary lattice paths counting. An advantage of the approach is that it does not require inversion of the Laplace-Stieltjes transfo
Zhang, Xing; Herbert, John M
2014-08-14
We revisit the calculation of analytic derivative couplings for configuration interaction singles (CIS), and derive and implement these couplings for its spin-flip variant for the first time. Our algorithm is closely related to the CIS analytic energy gradient algorithm and should be straightforward to implement in any quantum chemistry code that has CIS analytic energy gradients. The additional cost of evaluating the derivative couplings is small in comparison to the cost of evaluating the gradients for the two electronic states in question. Incorporation of an exchange-correlation term provides an ad hoc extension of this formalism to time-dependent density functional theory within the Tamm-Dancoff approximation, without the need to invoke quadratic response theory or evaluate third derivatives of the exchange-correlation functional. Application to several different conical intersections in ethylene demonstrates that minimum-energy crossing points along conical seams can be located at substantially reduced cost when analytic derivative couplings are employed, as compared to use of a branching-plane updating algorithm that does not require these couplings. Application to H3 near its D(3h) geometry demonstrates that correct topology is obtained in the vicinity of a conical intersection involving a degenerate ground state.
Energy Technology Data Exchange (ETDEWEB)
Honda, Makio C.; Kawakami, Hajime; Kitamura, Minoru; Takigawa, Masayuki [Japan Agency for Marine-Earth Science and Technology, 237-0031 (Japan); Aono, Tatsuo [National Institute for Radiological Sciences, Chiba, 206-8555 (Japan); Aoyama, Michio [Fukushima University, Fukushima, 960-1296 (Japan); Masumoto, Yukio [University of Tokyo, Bunkyo, 113-0033 (Japan); Nagao, Seiya [Kanazawa University, Nomi,923-1224 (Japan)
2014-07-01
At a pelagic time-series station in the western North Pacific, K2 (47 N / 160 E, water depth: ca. 5200 m), the radiocesium, which was derived from TEPCO's Fukushima Daiichi Nuclear Power Plant accident, in seawater, suspended substances, zooplankton, sinking particle and seafloor sediment had been observed since the accident. Based on the mathematical simulation, Fukushima-derived radiocesium likely arrived at K2 within a week after the accident as an eolian dust (Honda et al., Geochemical Journal 2012). Concentrations of radiocesium ({sup 137}Cs) in the surface seawater were ca. 0.008, 0.018 and 0.005 Bq kg{sup -1} at April 2011, July 2011, and June 2012, respectively, against ca. 0.001 Bq kg{sup -1} before the accident. Concentrations of {sup 137}Cs in zooplankton and suspended substances near surface were much higher than that of surface seawater, comparable each other within variability and generally decreased with time from ca. 20 ∼ 70 Bq kg{sup -1} in April 2011 to ca. 2 ∼ 10 Bq kg{sup -1} in June 2012. Thus concentration factor (the ratio of radiocesium concentration of zooplankton or suspended substances to that of seawater) tended to decrease with time and distribution of radiocesium between seawater and zooplankton or suspended substances were still not under steady state. Fukushima-derived {sup 137}Cs was detected at the first time from sinking particles collected between 26 March and April 6 2011 at 500 m and 6 April and 18 April 2011 at 4810 m. Concentration of {sup 137}Cs of sinking particle ranged from ca. 20 to 400 Bq kg{sup -1} with average of ca. 80 Bq kg{sup -1}. Maximum concentration was observed in late March 2011 at 500 m while in early June 2011 at 4810 m. Concentrations of radiocesium was below detection limit after February 2012 at 500 m and middle April 2012 at 4810 m. Although sinking velocity between 500 m and 4810 m was estimated to be larger than ca. 180 m day{sup -1} in previous report (Honda et al., Biogeosciences 2013
Institute of Scientific and Technical Information of China (English)
张天伟; 聂磊; 贺振欢
2015-01-01
Three organization modes ,i.e. ,waiting for simultaneous integrated maintain time(SIMT) on a high speed railway(HSR) station(WHRS) ,transfer from HSR to conventional railway(CR) before SIMT and arri‐ving at the destination(T HCD) on the CR , transfer from HSR to CR before SIM T and from CR to HSR after SIMT(HCCH),were proposed according to SIMT on HSR .The operation process of sunset‐departure and sunrise‐arrival trains in every organization mode was analyzed . The nonlinear integer program optimization model of operation mode choice was built , with passenger satisfaction on departure and arrival moments and fare attraction w hich affect passengers'choice behavior , section carrying capacity and difficulty of transportation organization adjustment which affect the quality and quantity of rail transport products supply as objective func‐tion . Variable logical , the moment of train operation process , the relation betw een the selection of cities and the arrival or departure moment at the cities ,and the number of arrival‐departrue railway lines were considered in its constraints .An appropriate size numerical example shows that when SIMT from 00 :00 to 04 :00 ,WHRS and 300 km/h of multiple units are preferred for the long distance train OD . T HCD and 250 km/h of multiple units are the first choice for the medium distance train OD .%在全线矩形天窗下提出等线、下线、下线‐上线共3种高速铁路夕发朝至列车开行模式，分析每种模式下列车运行过程。以影响旅客选择行为的列车始发、终到时刻满意度、票价吸引力、影响铁路运输产品供给数量及质量的区段通过能力和运输组织难度为目标函数，构建满足变量逻辑约束、列车运行过程约束、关键地点与运行时刻约束、到发线数量约束的开行模式选择非线性整数规划优化模型，通过算例应用验证了构建模型的可行性和有效性。研究结果表明：在0：00～04：00开
DEFF Research Database (Denmark)
Chen, Gang; GOVINDAN, Kannan; Golias, Mihalis M.
2012-01-01
This study proposes a methodology to optimize truck arrival patterns to reduce emissions from idling truck engines at marine container terminals. A bi-objective model is developed minimizing both truck waiting times and truck arrival pattern change. The truck waiting time is estimated via...... a queueing network. Based on the waiting time, truck idling emissions are estimated. The proposed methodology is evaluated with a case study, where truck arrival rates vary over time. We propose a Genetic Algorithm based heuristic to solve the resulting problem. Result shows that, a small shift of truck...... arrivals can significantly reduce truck emissions, especially at the gate....
Directory of Open Access Journals (Sweden)
Ahmet Bekir
2014-09-01
Full Text Available In this paper, the fractional partial differential equations are defined by modified Riemann–Liouville fractional derivative. With the help of fractional derivative and traveling wave transformation, these equations can be converted into the nonlinear nonfractional ordinary differential equations. Then G′G-expansion method is applied to obtain exact solutions of the space-time fractional Burgers equation, the space-time fractional KdV-Burgers equation and the space-time fractional coupled Burgers’ equations. As a result, many exact solutions are obtained including hyperbolic function solutions, trigonometric function solutions and rational solutions. These results reveal that the proposed method is very effective and simple in performing a solution to the fractional partial differential equation.
Emergency contraception use up -- new ECP arrives.
1999-09-01
The first progestin-only dedicated emergency contraceptive pill (ECP) is about to enter the US market. The arrival of Plan B, a levonorgestrel-only ECP produced by the Women's Capital Corporation (WCC) of Seattle, has been long awaited by providers in the US because of it is more effective and produces fewer side effects than does the combined regimen. The WCC is taking a different marketing and distributing approach to emergency contraception than its competitor, Gynetics, focusing on existing ECP provider/dispensers such as Planned Parenthood affiliates, major Title X programs, and college/university student health centers. The FDA has also approved a change in product labeling for Gynetics¿ ECU Preven. The change, marked by the disappearance of the "Black Box Warning," puts the benefits and risks of emergency contraception in perspective, according to a Gynetics executive. It further eliminates substantial restrictions on the company's ability to communicate directly to the consumer and to the medical professional. The FDA¿s decisions should help to accelerate the process of building awareness of emergency contraception and its availability in the US.
Energy Technology Data Exchange (ETDEWEB)
Fischer, Michael A.; Kartalis, Nikolaos; Aspelin, Peter; Albiin, Nils; Brismar, Torkel B. [Karolinska University Hospital, Division of Medical Imaging and Technology, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm (Sweden); Leidner, Bertil; Svensson, Anders [Karolinska University Hospital, Division of Medical Imaging and Technology, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm (Sweden); Karolinska University Hospital Huddinge, Department of Radiology, Stockholm (Sweden)
2014-01-15
To assess feasibility and image quality (IQ) of a new post-processing algorithm for retrospective extraction of an optimised multi-phase CT (time-resolved CT) of the liver from volumetric perfusion imaging. Sixteen patients underwent clinically indicated perfusion CT using 4D spiral mode of dual-source 128-slice CT. Three image sets were reconstructed: motion-corrected and noise-reduced (MCNR) images derived from 4D raw data; maximum and average intensity projections (time MIP/AVG) of the arterial/portal/portal-venous phases and all phases (total MIP/ AVG) derived from retrospective fusion of dedicated MCNR split series. Two readers assessed the IQ, detection rate and evaluation time; one reader assessed image noise and lesion-to-liver contrast. Time-resolved CT was feasible in all patients. Each post-processing step yielded a significant reduction of image noise and evaluation time, maintaining lesion-to-liver contrast. Time MIPs/AVGs showed the highest overall IQ without relevant motion artefacts and best depiction of arterial and portal/portal-venous phases respectively. Time MIPs demonstrated a significantly higher detection rate for arterialised liver lesions than total MIPs/AVGs and the raw data series. Time-resolved CT allows data from volumetric perfusion imaging to be condensed into an optimised multi-phase liver CT, yielding a superior IQ and higher detection rate for arterialised liver lesions than the raw data series. (orig.)
Negraru, Petru; Golden, Paul
2017-01-01
SUMMARYLong term ground truth observations were collected at two infrasound arrays in Nevada to investigate how seasonal atmospheric variations affect the detection, travel time and signal characteristics (azimuth, trace velocity, frequency content and amplitudes) of infrasonic arrivals at regional distances. The arrays were located in different azimuthal directions from a munition disposal facility in Nevada. FNIAR, located 154 km north of the source has a high detection rate throughout the year. Over 90% of the detonations have travel times indicative of stratospheric arrivals, while tropospheric waveguides are observed from only 27% of the detonations. The second array, DNIAR, located 293 km southeast of the source exhibits strong seasonal variations with high stratospheric detection rates in winter and the virtual absence of stratospheric arrivals in summer. Tropospheric waveguides and thermospheric arrivals are also observed for DNIAR. Modelling through the Naval Research Laboratory Ground to Space (G2S) atmospheric sound speeds leads to mixed results: FNIAR arrivals are usually not predicted to be present at all (either stratospheric or tropospheric), while DNIAR arrivals are usually correctly predicted, but summer arrivals show a consistent travel time bias. In the end we show the possible improvement in location using empirically calibrated travel time and azimuth observations. Using the Bayesian Infrasound Source Localization we show that we can decrease the area enclosed by the 90% credibility contours by a factor of 2.5.
STS-93 Pilot Ashby arrives at SLF for launch
1999-01-01
STS-93 Pilot Jeffrey S. Ashby lands at Kennedy Space Center's Shuttle Landing Facility (SLF) aboard a T-38 jet aircraft. He and other crew members Commander Eileen Collins and Mission Specialists Steven A. Hawley (Ph.D.), Catherine G. 'Cady' Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES), are arriving for pre-launch activities. STS-93 is Ashby's inaugural Shuttle flight. The primary mission of STS-93 is the release of the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The new telescope is 20 to 50 times more sensitive than any previous X-ray telescope and is expected to unlock the secrets of supernovae, quasars and black holes.
Forecasting tourist arrivals to balearic islands using genetic programming
Directory of Open Access Journals (Sweden)
Rosselló-Nadal, Jaume
2007-01-01
Full Text Available Traditionally, univariate time-series models have largely dominated forecasting for international tourism demand. In this paper, the ability of a Genetic Program (GP to predict monthly tourist arrivals from UK and Germany to Balearic Islands (Spain is explored. GP has already been employed satisfactorily in different scientific areas, including economics. The technique shows different advantages regarding to other forecasting methods. Firstly, it does not assume a priori a rigid functional form of the model. Secondly, it is more robust and easy-to-use than other non-parametric methods. Finally, it provides explicitly a mathematical equation which allows a simple ad hoc interpretation of the results. Comparing the performance of the proposed technique against other method commonly used in tourism forecasting (no-change model, Moving Average and ARIMA, the empirical results reveal that GP can be a valuable tool in this field.
Predictors of early arrival at the emergency department in acute ischaemic stroke.
LENUS (Irish Health Repository)
Curran, C
2012-01-31
BACKGROUND: A requirement of an effective acute stroke service is the early arrival of patients to the hospital emergency department (ED). This will allow the possible use of thrombolytic therapy or other acute interventions within a limited time window. AIMS: We investigated the predictors of early arrival in a single hospital serving a mixed urban and rural catchment area. METHODS: A retrospective review of all case notes for 1 year was performed. RESULTS: Of 105 acute strokes, 91 were cerebral infarcts and a total of 71 cases presenting initially to the ED had timing available for analysis. 39.4% presented within 3 h, and 12.7% were potentially suitable for thrombolysis. Those living closer to the hospital were not more likely to arrive within 3 h (Z = -0.411, p = 0.68). Presenting directly to the hospital by emergency services (or private transport) was significantly associated with early arrival in a univariate comparison (p < 0.001), and in a multivariate model. CONCLUSION: The only independent predictor of early arrival to the ED is direct presentation. Improved public education of the importance of recognition of stroke symptoms and rapid contact with the emergency services will improve the early attendance following acute stroke, allowing increased use of acute stroke treatments.
An Analysis of the Relationship Between the Heat Index and Arrivals in the Emergency Department
Levy, Matthew; Broccoli, Morgan; Cole, Gai; Jenkins, J Lee; Klein, Eili Y.
2015-01-01
Background: Heatwaves are one of the most deadly weather-related events in the United States and account for more deaths annually than hurricanes, tornadoes, floods, and earthquakes combined. However, there are few statistically rigorous studies of the effect of heatwaves on emergency department (ED) arrivals. A better understanding of this relationship can help hospitals plan better and provide better care for patients during these types of events. Methods: A retrospective review of all ED patient arrivals that occurred from April 15 through August 15 for the years 2008 through 2013 was performed. Daily patient arrival data were combined with weather data (temperature and humidity) to examine the potential relationships between the heat index and ED arrivals as well as the length of time patients spend in the ED using generalized additive models. In particular the effect the 2012 heat wave that swept across the United States, and which was hypothesized to increase arrivals was examined. Results: While there was no relationship found between the heat index and arrivals on a single day, a non-linear relationship was found between the mean three-day heat index and the number of daily arrivals. As the mean three-day heat index initially increased, the number of arrivals significantly declined. However, as the heat index continued to increase, the number of arrivals increased. It was estimated that there was approximately a 2% increase in arrivals when the mean heat index for three days approached 100°F. This relationship was strongest for adults aged 18-64, as well as for patients arriving with lower acuity. Additionally, a positive relationship was noted between the mean three-day heat index and the length of stay (LOS) for patients in the ED, but no relationship was found for the time from which a patient was first seen to when a disposition decision was made. No significant relationship was found for the effect of the 2012 heat wave on ED arrivals, though it
The mental health of unaccompanied refugee minors on arrival in the host country.
Vervliet, Marianne; Meyer Demott, Melinda A; Jakobsen, Marianne; Broekaert, Eric; Heir, Trond; Derluyn, Ilse
2014-02-01
Despite increasing numbers of unaccompanied refugee minors (UM) in Europe and heightened concerns for this group, research on their mental health has seldom included the factor "time since arrival." As a result, our knowledge of the mental health statuses of UM at specific points in time and over periods in their resettlement trajectories in European host countries is limited. This study therefore examined the mental health of UM shortly after their arrival in Norway (n = 204) and Belgium (n = 103) through the use of self-report questionnaires (HSCL-37A, SLE, RATS, HTQ). High prevalence scores of anxiety, depression and posttraumatic stress disorder (PTSD) symptoms were found. In addition, particular associations were found with the number of traumatic events the UM reported. The results indicate that all UM have high support needs on arrival in the host country. Longitudinal studies following up patterns of continuity and change in their mental health during their trajectories in the host country are necessary.
Linking the fractional derivative and the Lomnitz creep law to non-Newtonian time-varying viscosity
Pandey, Vikash; Holm, Sverre
2016-09-01
Many of the most interesting complex media are non-Newtonian and exhibit time-dependent behavior of thixotropy and rheopecty. They may also have temporal responses described by power laws. The material behavior is represented by the relaxation modulus and the creep compliance. On the one hand, it is shown that in the special case of a Maxwell model characterized by a linearly time-varying viscosity, the medium's relaxation modulus is a power law which is similar to that of a fractional derivative element often called a springpot. On the other hand, the creep compliance of the time-varying Maxwell model is identified as Lomnitz's logarithmic creep law, making this possibly its first direct derivation. In this way both fractional derivatives and Lomnitz's creep law are linked to time-varying viscosity. A mechanism which yields fractional viscoelasticity and logarithmic creep behavior has therefore been found. Further, as a result of this linking, the curve-fitting parameters involved in the fractional viscoelastic modeling, and the Lomnitz law gain physical interpretation.
Directory of Open Access Journals (Sweden)
Ben L Phillips
Full Text Available Pathogen spread can cause population declines and even species extinctions. Nonetheless, in the absence of tailored monitoring schemes, documenting pathogen spread can be difficult. In the case of worldwide amphibian declines the best present understanding is that the chytrid fungus Batrachochytrium dendrobatidis (Bd has recently spread, causing amphibian declines and extinction in the process. However, good evidence demonstrating pathogen arrival followed by amphibian decline is rare, and analysis of putative evidence is often inadequate. Here we attempt to examine the relationship between Bd arrival and amphibian decline across north-eastern Australia, using sites where a wave-like pattern of amphibian decline was first noticed and at which intensive research has since been conducted. We develop an analytical framework that allows rigorous estimation of pathogen arrival date, which can then be used to test for a correlation between the time of pathogen arrival and amphibian decline across sites. Our results show that, with the current dataset, the earliest possible arrival date of Bd in north-eastern Australia is completely unresolved; Bd could have arrived immediately before sampling commenced or may have arrived thousands of years earlier, the present data simply cannot say. The currently available data are thus insufficient to assess the link between timing of pathogen arrival and population decline in this part of the world. This data insufficiency is surprising given that there have been decades of research on chytridiomycosis in Australia and that there is a general belief that the link between Bd arrival and population decline is well resolved in this region. The lack of data on Bd arrival currently acts as a major impediment to determining the role of environmental factors in driving the global amphibian declines, and should be a major focus of future research.
Derivation of asymptotic two-dimensional time-dependent equations for ocean wave propagation
Lannes, David
2007-01-01
A general method for the derivation of asymptotic nonlinear shallow water and deep water models is presented. Starting from a general dimensionless version of the water-wave equations, we reduce the problem to a system of two equations on the surface elevation and the velocity potential at the free surface. These equations involve a Dirichlet-Neumann operator and we show that all the asymptotic models can be recovered by a simple asymptotic expansion of this operator, in function of the shallowness parameter (shallow water limit) or the steepness parameter (deep water limit). Based on this method, a new two-dimensional fully dispersive model for small wave steepness is also derived, which extends to uneven bottom the approach developed by Matsuno \\cite{matsuno3} and Choi \\cite{choi}. This model is still valid in shallow water but with less precision than what can be achieved with Green-Naghdi model, when fully nonlinear waves are considered. The combination, or the coupling, of the new fully dispersive equati...
Analytical Solutions of a Space-Time Fractional Derivative of Groundwater Flow Equation
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Abdon Atangana
2014-01-01
Full Text Available The classical Darcy law is generalized by regarding the water flow as a function of a noninteger order derivative of the piezometric head. This generalized law and the law of conservation of mass are then used to derive a new equation for groundwater flow. Two methods including Frobenius and Adomian decomposition method are used to obtain an asymptotic analytical solution to the generalized groundwater flow equation. The solution obtained via Frobenius method is valid in the vicinity of the borehole. This solution is in perfect agreement with the data observed from the pumping test performed by the institute for groundwater study on one of their boreholes settled on the test site of the University of the Free State. The test consisted of the pumping of the borehole at the constant discharge rate Q and monitoring the piezometric head for 350 minutes. Numerical solutions obtained via Adomian method are compared with the Barker generalized radial flow model for which a fractal dimension for the flow is assumed. Proposition for uncertainties in groundwater studies was given.
Fedderke, Johannes; Luiz, John; de Kadt, Raphael
2008-01-01
Recent cross-country growth studies have found that ethnolinguistic fractionalization is an important explanatory variable of long-run growth performance. This paper highlights some limitations of cross-country studies by focusing on the time series evidence for South Africa. In presenting variation over time in a number of social dimensions, this…
Directory of Open Access Journals (Sweden)
K. Srinivasa Rao
2011-01-01
Full Text Available A two node tandem communication network with dynamic bandwidth allocation (DBA having two stage direct bulk arrivals is developed and analyzed. The messages arriving to the source are packetized and stored in the buffers for forward transmission. Dynamic bandwidth allocation strategy is proposed by adjusting the transmission rate at every node just before transmission of each packet. The arrival and transmission processes at each node are characterized through compound Poisson and Poisson processes such that several of the statistical characteristics of communication networks identically matches. Using the difference - differential equations, the performance measures like the joint probability generating function of the content of two buffers, average buffer content, mean delays and throughput of nodes are derived and analyzed. It is observed that the bulk arrivals at two nodes and DBA have significant influence on performance measures. This network is much useful in Tele and Satellite communications.
Huang, Qing; Zhdanov, Renat
2014-09-01
In this paper, group analysis of the time fractional Harry-Dym equation with Riemann-Liouville derivative is performed. Its maximal symmetry group in Lie’s sense and the corresponding optimal system of subgroups are determined. Similarity reductions of the equation under study are performed. As a result, the reduced fractional ordinary differential equations are deduced, and some group invariant solutions in explicit form are obtained as well.
Multiplicative processes and power laws in human reaction times derived from hyperbolic functions
Energy Technology Data Exchange (ETDEWEB)
Medina, José M., E-mail: jmanuel@fisica.uminho.pt [Center for Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal)
2012-04-09
In sensory psychophysics reaction time is a measure of the stochastic latency elapsed from stimulus presentation until a sensory response occurs as soon as possible. A random multiplicative model of reaction time variability is investigated for generating the reaction time probability density functions. The model describes a generic class of hyperbolic functions by Piéron's law. The results demonstrate that reaction time distributions are the combination of log-normal with power law density functions. A transition from log-normal to power law behavior is found and depends on the transfer of information in neurons. The conditions to obtain Zipf's law are analyzed. -- Highlights: ► I have examined human reaction time variability by random multiplicative processes. ► A transition from power law to log-normal distributions is described. ► The transition depends on the transfer of information in neurons. ► Zipf's law in reaction time distributions depends on the exponent of Piéron's law.
Development and assessment of real-time tropospheric products derived from GNSS
Vaclavovic, Pavel; Dousa, Jan; Eben, K.
2016-07-01
The GNSS-meteorology, i.e. monitoring the water vapour content in the troposphere through the analysis of GNSS observations, provides GNSS real-time tropospheric products in support of numerical weather prediction (NWP) and severe weather event monitoring. The real-time ultra-fast and high-resolution GNSS tropospheric products, such as zenith total delay (ZTD) and horizontal gradients describing the first-order anisotropy of the troposphere, has been developed and routinely generated at the Geodetic Observatory Pecny for several years. The poster summarizes results of the evaluation of real-time tropospheric products with respect to the IGS and EUREF final products and introduces a new online system for the monitoring and comparison of the products with other tropospheric solutions.The accuracy of real-time ZTD achieved 5-10 mm, which fulfills the requirements for NWP nowcasting applications defined by the EUMETNET EIG GNSS water vapour programme (E-GVAP). Corresponding tropospheric parameters for GNSS model were also calculated using meteorological data from numerical weather predictions and these are routinely compared with GNSS-based real-time products. The parameters from the NWP represents augmentation tropospheric corrections for a future use in applications, e.g. real-time kinematic positioning and navigation.
Errors in 'BED'-derived estimates of HIV incidence will vary by place, time and age.
Directory of Open Access Journals (Sweden)
Timothy B Hallett
Full Text Available BACKGROUND: The BED Capture Enzyme Immunoassay, believed to distinguish recent HIV infections, is being used to estimate HIV incidence, although an important property of the test--how specificity changes with time since infection--has not been not measured. METHODS: We construct hypothetical scenarios for the performance of BED test, consistent with current knowledge, and explore how this could influence errors in BED estimates of incidence using a mathematical model of six African countries. The model is also used to determine the conditions and the sample sizes required for the BED test to reliably detect trends in HIV incidence. RESULTS: If the chance of misclassification by BED increases with time since infection, the overall proportion of individuals misclassified could vary widely between countries, over time, and across age-groups, in a manner determined by the historic course of the epidemic and the age-pattern of incidence. Under some circumstances, changes in BED estimates over time can approximately track actual changes in incidence, but large sample sizes (50,000+ will be required for recorded changes to be statistically significant. CONCLUSIONS: The relationship between BED test specificity and time since infection has not been fully measured, but, if it decreases, errors in estimates of incidence could vary by place, time and age-group. This means that post-assay adjustment procedures using parameters from different populations or at different times may not be valid. Further research is urgently needed into the properties of the BED test, and the rate of misclassification in a wide range of populations.
TRACON Aircraft Arrival Planning and Optimization Through Spatial Constraint Satisfaction
Bergh, Christopher P.; Krzeczowski, Kenneth J.; Davis, Thomas J.; Denery, Dallas G. (Technical Monitor)
1995-01-01
A new aircraft arrival planning and optimization algorithm has been incorporated into the Final Approach Spacing Tool (FAST) in the Center-TRACON Automation System (CTAS) developed at NASA-Ames Research Center. FAST simulations have been conducted over three years involving full-proficiency, level five air traffic controllers from around the United States. From these simulations an algorithm, called Spatial Constraint Satisfaction, has been designed, coded, undergone testing, and soon will begin field evaluation at the Dallas-Fort Worth and Denver International airport facilities. The purpose of this new design is an attempt to show that the generation of efficient and conflict free aircraft arrival plans at the runway does not guarantee an operationally acceptable arrival plan upstream from the runway -information encompassing the entire arrival airspace must be used in order to create an acceptable aircraft arrival plan. This new design includes functions available previously but additionally includes necessary representations of controller preferences and workload, operationally required amounts of extra separation, and integrates aircraft conflict resolution. As a result, the Spatial Constraint Satisfaction algorithm produces an optimized aircraft arrival plan that is more acceptable in terms of arrival procedures and air traffic controller workload. This paper discusses the current Air Traffic Control arrival planning procedures, previous work in this field, the design of the Spatial Constraint Satisfaction algorithm, and the results of recent evaluations of the algorithm.
19 CFR 123.61 - Baggage arriving in baggage car.
2010-04-01
... 19 Customs Duties 1 2010-04-01 2010-04-01 false Baggage arriving in baggage car. 123.61 Section... car. An inward foreign manifest on Customs Form 7533 shall be used for all baggage arriving in baggage cars....
A Prediction System Using a P2P Overlay Network for a Bus Arrival System
Directory of Open Access Journals (Sweden)
Ssu-Hsuan Lu
2014-01-01
Full Text Available Along with the evolution of times and the surge of metropolitan populations, government agencies often promote the construction of public transport. Unlike rail transportation or rapid transit systems, it is often difficult to estimate the vehicle arrival times at each station in a bus transportation system due to metropolitan transportation congestion. Traffic status is often monitored using wireless sensor networks (WSNs. However, WSNs are always separated from one another spatially. Recent studies have considered the connection of multiple sensor networks. This study considers a combination view of peer-to-peer (P2P overlay networks and WSN architecture to predict bus arrival times. Each bus station, which is also a P2P overlay peer, is connected in a P2P overlay network. A sensor installed in each bus can receive data via peers to obtain the moving speed of a bus. Then, each peer can exchange its data to predict bus arrival times at bus stations. This method can considerably increase the accuracy with which bus arrival times can be predicted and can provide traffic status with high precision. Furthermore, these data can also be used to plan new bus routes according to the information gathered.
Multipath Separation-Direction of Arrival (MS-DOA) with Genetic Search Algorithm for HF channels
Arikan, Feza; Koroglu, Ozan; Fidan, Serdar; Arikan, Orhan; Guldogan, Mehmet B.
2009-09-01
Direction-of-Arrival (DOA) defines the estimation of arrival angles of an electromagnetic wave impinging on a set of sensors. For dispersive and time-varying HF channels, where the propagating wave also suffers from the multipath phenomena, estimation of DOA is a very challenging problem. Multipath Separation-Direction of Arrival (MS-DOA), that is developed to estimate both the arrival angles in elevation and azimuth and the incoming signals at the output of the reference antenna with very high accuracy, proves itself as a strong alternative in DOA estimation for HF channels. In MS-DOA, a linear system of equations is formed using the coefficients of the basis vector for the array output vector, the incoming signal vector and the array manifold. The angles of arrival in elevation and azimuth are obtained as the maximizers of the sum of the magnitude squares of the projection of the signal coefficients on the column space of the array manifold. In this study, alternative Genetic Search Algorithms (GA) for the maximizers of the projection sum are investigated using simulated and experimental ionospheric channel data. It is observed that GA combined with MS-DOA is a powerful alternative in online DOA estimation and can be further developed according to the channel characteristics of a specific HF link.
Cony, Marco; Liria, Juan; Weisenberg, Ralf; Serrano, Enrique
2014-05-01
Accurate knowledge of solar irradiance components at the earth surface is of highly interest in many scientific and technology branches concerning meteorology, climate, agriculture and solar energy applications. In the specific case of solar energy systems the solar resource analysis with accuracy is a first step in every project since it is a required data for design, power output estimations, systems simulations and risk assessments. Solar radiation measurement availability is increasing both in spatial density and in historical archiving. However, it is still quite limited and most of the situations cannot make use of a long term ground database of high quality since solar irradiance is not generally measured where users need data. Satellite-derived solar radiation estimations are a powerful and valuable tool for solar resource assessment studies that have achieved a relatively high maturity due to years of developments and improvements. However, several sources of uncertainty are still present in satellite-derived methods. In particular, the strong influence of atmospheric attenuation information as input to the method is one of the main topics of improvement. Since solar radiation attenuation by atmospheric aerosols, and water vapor in a second place, is, after clouds, the second most important factor determining solar radiation, and particularly direct normal irradiance, the accurate knowledge of aerosol optical depth and water vapor content is relevant in the final output of satellite-derived methods. This present work, two different datasets we are used for extract atmospheric attenuation information. On the one hand the monthly mean values of the Linke turbidity factor from Meteotest database, which are twelve unique values of the Linke turbidity worldwide with a spatial resolution of 1/12º. On the other hand, daily values of AOD (Aerosol Optical Depth) at 550 nm, Angstrom alpha exponent and water vapor column were taken from a gridded database that
Can a Time Fractional-Derivative Model Capture Scale-Dependent Dispersion in Saturated Soils?
Garrard, Rhiannon M; Zhang, Yong; Wei, Song; Sun, HongGuang; Qian, Jiazhong
2017-07-10
Time nonlocal transport models such as the time fractional advection-dispersion equation (t-fADE) were proposed to capture well-documented non-Fickian dynamics for conservative solutes transport in heterogeneous media, with the underlying assumption that the time nonlocality (which means that the current concentration change is affected by previous concentration load) embedded in the physical models can release the effective dispersion coefficient from scale dependency. This assumption, however, has never been systematically examined using real data. This study fills this historical knowledge gap by capturing non-Fickian transport (likely due to solute retention) documented in the literature (Huang et al. 1995) and observed in our laboratory from small to intermediate spatial scale using the promising, tempered t-fADE model. Fitting exercises show that the effective dispersion coefficient in the t-fADE, although differing subtly from the dispersion coefficient in the standard advection-dispersion equation, increases nonlinearly with the travel distance (varying from 0.5 to 12 m) for both heterogeneous and macroscopically homogeneous sand columns. Further analysis reveals that, while solute retention in relatively immobile zones can be efficiently captured by the time nonlocal parameters in the t-fADE, the motion-independent solute movement in the mobile zone is affected by the spatial evolution of local velocities in the host medium, resulting in a scale-dependent dispersion coefficient. The same result may be found for the other standard time nonlocal transport models that separate solute retention and jumps (i.e., displacement). Therefore, the t-fADE with a constant dispersion coefficient cannot capture scale-dependent dispersion in saturated porous media, challenging the application for stochastic hydrogeology methods in quantifying real-world, preasymptotic transport. Hence improvements on time nonlocal models using, for example, the novel subordination
Wei, Song; Chen, Wen; Hon, Y. C.
2016-11-01
This paper investigates the temporal effects in the modeling of flows through porous media and particles transport. Studies will be made among the time fractional diffusion model and two classical nonlinear diffusion models. The effects of the parameters upon the mentioned models have been studied. By simulating the sub-diffusion processes and comparing the numerical results of these models under different boundary conditions, we can conclude that the time fractional diffusion model is more suitable for simulating the sub-diffusion with steady diffusion rate; whereas the nonlinear models are more appropriate for depicting the sub-diffusion under changing diffusion rate.
Tomographic lifetime imaging using combined early- and late-arriving photons.
Hou, Steven S; Rice, William L; Bacskai, Brian J; Kumar, Anand T N
2014-03-01
We present a novel, hybrid approach for time domain fluorescence tomography that efficiently combines lifetime multiplexing using late-arriving or asymptotic photons, with the high spatial resolution capability of early photon tomography. We also show that a decay amplitude-based asymptotic approach is superior to direct inversion of late-arriving photons for tomographic lifetime imaging within turbid media. The hybrid reconstruction approach is experimentally shown to recover fluorescent inclusions separated as close as 1.4 mm, with improved resolution and reduced cross talk compared to just using early photons or the asymptotic approach alone.
(Batch) Markovian arrival processes: the identifiability issue and other applied aspects
Rodríguez César, Joanna Virginia
2015-01-01
Mención Internacional en el título de doctor This dissertation is mainly motivated by the problem of statistical modeling via a specific point process, namely, the Batch Markovian arrival processes. Point processes arise in a wide range of situations of our daily activities, such as people arriving to a bank, claims of an insurance company or failures in a system. They are defined by the occurrence of an event at a specific time, where the event occurrences may be understood from different...
Derivation of Apollo 14 High-Al Basalts at Discrete Times: Rb-Sr Isotopic Constraints
Hui. Hejiu; Neal, Clive, R.; Shih, Chi-Yu; Nyquist, Laurence E.
2012-01-01
Pristine Apollo 14 (A-14) high-Al basalts represent the oldest volcanic deposits returned from the Moon [1,2] and are relatively enriched in Al2O3 (>11 wt%) compared to other mare basalts (7-11 wt%). Literature Rb-Sr isotopic data suggest there are at least three different eruption episodes for the A-14 high-Al basalts spanning the age range approx.4.3 Ga to approx.3.95 Ga [1,3]. Therefore, the high-Al basalts may record lunar mantle evolution between the formation of lunar crust (approx.4.4 Ga) and the main basin-filling mare volcanism (basalts were originally classified into five compositional groups [5,6], and then regrouped into three with a possible fourth comprising 14072 based on the whole-rock incompatible trace element (ITE) ratios and Rb-Sr radiometric ages [7]. However, Rb-Sr ages of these basalts from different laboratories may not be consistent with each other because of the use of different 87Rb decay constants [8] and different isochron derivation methods over the last four decades. This study involved a literature search for Rb-Sr isotopic data previously reported for the high-Al basalts. With the re-calculated Rb-Sr radiometric ages, eruption episodes of A-14 high-Al basalts were determined, and their petrogenesis was investigated in light of the "new" Rb-Sr isotopic data and published trace element abundances of these basalts.
A conflict analysis of 4D descent strategies in a metered, multiple-arrival route environment
Izumi, K. H.; Harris, C. S.
1990-01-01
A conflict analysis was performed on multiple arrival traffic at a typical metered airport. The Flow Management Evaluation Model (FMEM) was used to simulate arrival operations using Denver Stapleton's arrival route structure. Sensitivities of conflict performance to three different 4-D descent strategies (clear-idle Mach/Constant AirSpeed (CAS), constant descent angle Mach/CAS and energy optimal) were examined for three traffic mixes represented by those found at Denver Stapleton, John F. Kennedy and typical en route metering (ERM) airports. The Monte Carlo technique was used to generate simulation entry point times. Analysis results indicate that the clean-idle descent strategy offers the best compromise in overall performance. Performance measures primarily include susceptibility to conflict and conflict severity. Fuel usage performance is extrapolated from previous descent strategy studies.
Marrying after arriving: The role of individuals' networks for immigrant choice of partner's origin.
del Rey Poveda, Alberto; Vono de Vilhena, Daniela
2014-03-01
This paper analyses the impact of social networks on the transition to marriage among recently arrived, single, immigrants in Spain. Our hypothesis states that the existence of individual networks at the moment of arrival strongly influences partner selection. Using the 2007 Spanish National Immigration Survey we apply competing risk models to estimate the likelihood of endogamous or exogamous marriage, for men and women separately. The analysis shows that among immigrant men and women, the presence of relatives or friends from their home-country at the time of arrival increases the probability of marriage to a co-national. Correspondingly, immigrants who obtained Spanish citizenship before migrating present higher chances of intermarriage, as they are likely to have more contact with the host society.
Advanced spring arrival of avian migrants on Tipperne, western Denmark, during 1929-2008
DEFF Research Database (Denmark)
Petersen, Troels Leuenhagen; Meltofte, Hans; Tøttrup, Anders P.
2012-01-01
in first arrival dates were confirmed by patterns seen in arrival of the first five or ten individuals. Overall, changes in environmental conditions (temperature, precipitation and the North Atlantic Oscillation) during winter and spring explained much of the changes in phenology. Interspecific variation......During the last decade, phenological studies have increased our knowledge on climate-induced changes in timing of avian migration. Much work has been done using long-term, standardised data. However, the vast majority of previous studies have focused on data covering 3-4 decades and limited...... was related to variation in climate. Overall, spring arrival advanced by a mean of 0.26 days/ year, corresponding to a three week advance during the 80 year study period. While short-distance migrants advanced on average 0.38 days/year, long-distance migrants only advanced 0.17 days/year. These patterns...
Advanced spring arrival of avian migrants on Tipperne, western Denmark, during 1929-2008
DEFF Research Database (Denmark)
Petersen, Troels Leuenhagen; Meltofte, Hans; Tøttrup, Anders P.
2012-01-01
was related to variation in climate. Overall, spring arrival advanced by a mean of 0.26 days/ year, corresponding to a three week advance during the 80 year study period. While short-distance migrants advanced on average 0.38 days/year, long-distance migrants only advanced 0.17 days/year. These patterns......During the last decade, phenological studies have increased our knowledge on climate-induced changes in timing of avian migration. Much work has been done using long-term, standardised data. However, the vast majority of previous studies have focused on data covering 3-4 decades and limited...... to specific species groups. In the present study, we analysed temporal patterns in spring arrival of 43 taxonomically diverse Fennoscandian bird species based on a long-term data series covering 80 years (1929-2008) from the Tipperne reserve in westernmost Denmark. Furthermore, we assessed how spring arrival...
Source profile derivation for an arc welding shop using time sequenced sampling and PIXE analysis
Formenti, P.; Van Den Heever, D. J.; Annegarn, H. J.
1998-03-01
Samples of particulate concentration inside a welding shop in Bloemfontein (South Africa) were collected for two weeks during August 1995 using a single stage time sequenced sampler (streaker sampler). Inorganic elemental concentrations (μg/m 3) for 12 metallic rods are melted through electric arc welding to join steel plates. The absence of proper ventilation in the building, due to the closing of doors and windows during winter conditions, results in accumulation of pollutants and in enhanced hazardous conditions for the workers. Analysis of temporal coincidences of elemental concentrations time series formed the basis for extracting the arc welding source profile. Major periodical and episodic contributors to the indoor pollution were qualitatively observed during the sampling period. Due to the hourly time resolution of the sampling, their different time dependence could be identified and isolated. The welding shop activities were found to be characterised by high metal concentrations ([Fe] up to 95 μg/m 3) and variations in the Cu-to-Fe and Mn-to-Fe ratios within 30% over a week period. Cr concentrations up to 7 μg/m 3 were detected over 8-h shift periods. A profile for soil dust in the welding shop air was extracted, and was found to be enriched in Cr, Mn and Fe. This identifies the existence of a secondary source of heavy metal particulate exposure, to which all the workers, not only welders during their shifts, are exposed.
Huang, Jiaguo; Weinfurter, Stefanie; Pinto, Pedro Caetano; Pretze, Marc; Kränzlin, Bettina; Pill, Johannes; Federica, Rodeghiero; Perciaccante, Rossana; Ciana, Leopoldo Della; Masereeuw, Rosalinde; Gretz, Norbert
2016-01-01
Evaluation of renal function is crucial for a number of clinical situations. Here, we reported a novel exogenous fluorescent marker (FITC-HPβCD) to real-time assess renal function by using a transcutaneous fluorescent detection technique. FITC-HPβCD was designed based on the principle of renal
Huang, J.; Weinfurter, S.; Pinto, P.C.; Pretze, M.; Kranzlin, B.; Pill, J.; Federica, R.; Perciaccante, R.; Ciana, L.D.; Masereeuw, R.; Gretz, N.
2016-01-01
Evaluation of renal function is crucial for a number of clinical situations. Here, we reported a novel exogenous fluorescent marker (FITC-HPbetaCD) to real-time assess renal function by using a transcutaneous fluorescent detection technique. FITC-HPbetaCD was designed based on the principle of renal
Huang, Jiaguo; Weinfurter, Stefanie; Pinto, Pedro Caetano; Pretze, Marc; Kränzlin, Bettina; Pill, Johannes; Federica, Rodeghiero; Perciaccante, Rossana; Ciana, Leopoldo Della; Masereeuw, Rosalinde; Gretz, Norbert
2016-10-19
Evaluation of renal function is crucial for a number of clinical situations. Here, we reported a novel exogenous fluorescent marker (FITC-HPβCD) to real-time assess renal function by using a transcutaneous fluorescent detection technique. FITC-HPβCD was designed based on the principle of renal clearance of designed drugs. It displays favorable fluorescent properties, high hydrophilicity, low plasma protein binding, and high stability in porcine liver esterase as well as in plasma and nontoxicity. More importantly, FITC-HPβCD can be efficiently and rapidly filtered by glomerulus and completely excreted into urine without proximal tubular reabsorption or secretion in rat models. Additionally, the marker was well-tolerated, with nearly 100% urinary recovery of the given doses, and no metabolism were found. Relying on this novel kidney function marker and transcutaneous devices, we demonstrate a rapid, robust, and convenient approach for real-time assessing renal function without the need of time-consuming blood and urine sample preparation. Our work provides a promising tool for noninvasive real-time monitoring of renal function in vivo.
Dependability of Data Derived from Time Sampling Methods with Multiple Observation Targets
Johnson, Austin H.; Chafouleas, Sandra M.; Briesch, Amy M.
2017-01-01
In this study, generalizability theory was used to examine the extent to which (a) time-sampling methodology, (b) number of simultaneous behavior targets, and (c) individual raters influenced variance in ratings of academic engagement for an elementary-aged student. Ten graduate-student raters, with an average of 7.20 hr of previous training in…
Hinterberger, F.; Weber, R.; Moeller, G.; Magnet, N.
2011-12-01
To meet the increasing demand of upcoming real-time (RT) applications the IGS (International GNSS Service) has initiated a real-time working group (RTIGS) to investigate the feasibility of real-time GNSS data distribution and the generation of derived products. The RTIGS activities are based on a network of global GNSS stations which are delivering their observation data in real-time (with a delay of a few seconds or less) to central processing facilities, and subsequently to potential users. The data transmission is performed via internet and the UDP- or Ntrip Protocol. Nowadays this real-time station network consists of approximately 80 stations. Scientific organizations and companies operating reference stations can participate in the working group either by delivering their data-streams via a central service or by providing real-time GNSS products such as precise clock and orbits corrections. This presentation deals with the contributions of the Institute of Geodesy and Geophysics (IGG), Technical University of Vienna to the IGS Real-Time Working Group. IGG provides on a regular basis GPS- clock corrections and precise orbit solutions. The quality of these products with respect to the RTIGS combined solution is highlighted. Furthermore the IGG RT-data stream is used for PPP positioning forwarded via the RTCM-standard format to a rover receiver. We can demonstrate a real-time single receiver positioning accuracy at the 1-2 dm level. Aside from the positioning aspect the potential of to derive related products such as tropospheric delays to contribute as low latency data source to weather forecast models is discussed.
Directory of Open Access Journals (Sweden)
NIKOLAI KOLEV
1980-10-01
Full Text Available To determine the usefulness of the time intervals obtained from the first derivative of apex cardiogram (dA/dt in assessing contraction and relaxation, 20 hemodynamically and angiographical1y investigated patients with coronary artery disease and 29 patients with hypertensive heart disease were studied."nAs a control group there were used 50 normal subjects. Since contraction and relaxation is dependent on preload and afterload, the time interval from R wave of electrocardiogram to the positive peak of dA/dt (R to dA/dt and two relaxation parameters derived from negative peak dA/dt were investigated, early relaxation index (ERI and total relaxation index (TRI. In patients with coronary artery disease all of these parameters were augmen- -- ted (R to dA/dt: 121 + 14 controls; ERI: 13.1 149 + 30 Versus + 8 - msec versus 76 + 14 msec for versus 4.3 + 5 in controls; TRI 71 + 18 for controls and also pat ients with hypertensive heart disease s howed similar change s ( ~ to dA/ cant c orrelatio ns between these indexes a nd some i nternally par ame t e r s of myocar d i a l performance were ob s erved . These findings indicate that s ystolic and diastolic time intervals me a s ured f rom the firs t de r i v a t i v e o f apex ca r d iogr am may be used a s a reliable indices for evaluation o f contraction and relaxation independently of p r e loa d and afterload. dt : 115 -+ 15 ms ec ; ERI: 9 . 5 +- 6 ; TRI: 81 +- 19 .Signi f I Measurement o f sustolic and diastolic time interval Is for c a rd i ac evaluation, such as isovolumetric c ont r a ction, preejection period, l eft ventricular ejection time and isovolumetric r elaxation time has been emphasized"nby many authors. However, these intervals are infl- •"nuenced by factors extraneous to contractility and rela1,2 xation, such as variations in preload and afterload To ov e r c ome the latter d i f f i cu l t y , Reale 3 proposed t o determine the time interval fr om ons et of ventricular
On a two-server finite queuing system with ordered entry and deterministic arrivals
Nawijn, W.M.
1984-01-01
Consider a two-server, ordered entry, queuing system with heterogeneous servers and finite waiting rooms in front of the servers. Service times are negative exponentially distributed. The arrival process is deterministic. A matrix solution for the steady state probabilities of the number of
Analysis of delay reducing and fuel saving sequencing and spacing algorithms for arrival traffic
Neuman, Frank; Erzberger, Heinz
1991-01-01
The air traffic control subsystem that performs sequencing and spacing is discussed. The function of the sequencing and spacing algorithms is to automatically plan the most efficient landing order and to assign optimally spaced landing times to all arrivals. Several algorithms are described and their statistical performance is examined. Sequencing brings order to an arrival sequence for aircraft. First-come-first-served sequencing (FCFS) establishes a fair order, based on estimated times of arrival, and determines proper separations. Because of the randomness of the arriving traffic, gaps will remain in the sequence of aircraft. Delays are reduced by time-advancing the leading aircraft of each group while still preserving the FCFS order. Tightly spaced groups of aircraft remain with a mix of heavy and large aircraft. Spacing requirements differ for different types of aircraft trailing each other. Traffic is reordered slightly to take advantage of this spacing criterion, thus shortening the groups and reducing average delays. For heavy traffic, delays for different traffic samples vary widely, even when the same set of statistical parameters is used to produce each sample. This report supersedes NASA TM-102795 on the same subject. It includes a new method of time-advance as well as an efficient method of sequencing and spacing for two dependent runways.
Seed arrival in tropical forest tree fall gaps.
Puerta-Pińero, Carolina; Muller-Landau, Helene C; Calderón, Osvaldo; Wright, S Joseph
2013-07-01
Tree deaths open gaps in closed-canopy forests, which allow light to reach the forest floor and promote seed germination and seedling establishment. Gap dependence of regeneration is an important axis of life history variation among forest plant species, and many studies have evaluated how plant species differ in seedling and sapling performance in gaps. However, relatively little is known about how seed arrival in gaps compares with seed arrival in the understory, even though seed dispersal by wind and animals is expected to be altered in gaps. We documented seed arrival for the first seven years after gap formation in the moist tropical forests of Barro Colorado Island (BCI), Panama, and evaluated how the amount and functional composition of arriving seeds compared with understory sites. On average, in the first three years after gap formation, 72% fewer seeds arrived in gaps than in the understory (207 vs. 740 seeds x m(-2) x yr(-1)). The reduction in number of arriving seeds fell disproportionately on animal-dispersed species, which suffered an 86% reduction in total seed number, while wind-dispersed species experienced only a 47% reduction, and explosively dispersed species showed increased seed numbers arriving. The increase in explosively dispersed seeds consisted entirely of the seeds of several shrub species, a result consistent with greater in situ seed production by explosively dispersed shrubs that survived gap formation or recruited immediately thereafter. Lianas did relatively better in seed arrival into gaps than did trees, suffering less of a reduction in seed arrival compared with understory sites. This result could in large part be explained by the greater predominance of wind dispersal among lianas: there were no significant differences between lianas and trees when controlling for dispersal syndromes. Our results show that seed arrival in gaps is very different from seed arrival in the understory in both total seeds arriving and functional
Miles, T.; Chapman, W. A.
1984-01-01
The planetary-scale components of the extratropical Northern Hemisphere troposphere-stratosphere 1973-74 winter circulation are diagnosed using separate time-mean temperature fields based on radiosonde and satellite observations. Meridional cross-sections of zonal wind together with, for zonal wavenumbers 1, 2 and 3, the streamfunction amplitude, phase and Eliassen-Palm flux are displayed, with the relative accuracy of the satellite-derived diagnostics assessed through comparison with the 'ground-truth' radiosonde information. The satellite and radiosonde diagnostics compare most favourably in terms of zonal wind speed and shear, direction of wave propagation and meridional wave structure - all of which are closely related to the differential properties of the atmospheric temperature field. The intensity of the satellite-derived patterns of tropospheric wave propagation is underestimated due to the effects of spatial smoothing and residual cloud contamination present in the satellite radiance measurements.
Chen, Yong; Yan, Zhenya
2017-01-01
The effect of derivative nonlinearity and parity-time-symmetric (PT -symmetric) potentials on the wave propagation dynamics is explored in the derivative nonlinear Schrödinger equation, where the physically interesting Scarf-II and harmonic-Hermite-Gaussian potentials are chosen. We study numerically the regions of unbroken and broken linear PT -symmetric phases and find some stable bright solitons of this model in a wide range of potential parameters even though the corresponding linear PT -symmetric phases are broken. The semielastic interactions between particular bright solitons and exotic incident waves are illustrated such that we find that particular nonlinear modes almost keep their shapes after interactions even if the exotic incident waves have evidently been changed. Moreover, we exert the adiabatic switching on PT -symmetric potential parameters such that a stable nonlinear mode with the unbroken linear PT -symmetric phase can be excited to another stable nonlinear mode belonging to the broken linear PT -symmetric phase.
Suzuki, Toshiyuki; Midonoya, Hitoshi; Shioi, Yuzo
2009-07-01
The analysis of chlorophylls and their derivatives by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry is described. Four matrices-sinapinic acid, a-cyano-4-hydroxycinnnamic acid, terthiophene, and 3-aminoquinoline-were examined to determine optimal conditions for analysis of the molecular mass and structure of chlorophyll a as a representative chlorophyll. Among them, terthiophene was the most efficient without releasing metal ions, although it caused fragmentation of the phytol-ester linkage. Terthiophene was useful for the analyses of chlorophyll derivatives as well as porphyrin products such as 8-deethyl-8-vinyl-chlorophyll a, pheophorbide a, pyropheophorbide a, bacteriochlorophyll a esterified phytol, and protoporphyrin IX. The current method is suitable for rapid and accurate determination of the molecular mass and structure of chlorophylls and porphyrins.
Kiyokawa, Shuji
2007-04-01
We give the derivation of the Fano profile (the resonance energy position, the resonance width Γ , and q value) from the time-dependent nonrelativistic density-functional theory (DFT) and propose a scheme for calculating the photoabsorption cross section of hot dense plasmas. As a consequence of this derivation, we show the line profile is obtained as a superposition of Fano and Lorentz profiles when the competition of two optically allowed bound-bound and bound-free transitions occurs. We also show the results of the photoabsorption cross section by applying our scheme to an Fe plasma (density is 7.85g/cm3 , temperature is 100eV ), where the calculation is carried out without numerical divergence for any photon energy. The calculated results are in good agreement with those of Grimaldi.
A unified approach for proportional-integral-derivative controller design for time delay processes
Energy Technology Data Exchange (ETDEWEB)
Shamsuzzoha, Mohammad [King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)
2015-04-15
An analytical design method for PI/PID controller tuning is proposed for several types of processes with time delay. A single tuning formula gives enhanced disturbance rejection performance. The design method is based on the IMC approach, which has a single tuning parameter to adjust the performance and robustness of the controller. A simple tuning formula gives consistently better performance as compared to several well-known methods at the same degree of robustness for stable and integrating process. The performance of the unstable process has been compared with other recently published methods which also show significant improvement in the proposed method. Furthermore, the robustness of the controller is investigated by inserting a perturbation uncertainty in all parameters simultaneously, again showing comparable results with other methods. An analysis has been performed for the uncertainty margin in the different process parameters for the robust controller design. It gives the guidelines of the M{sub s} setting for the PI controller design based on the process parameters uncertainty. For the selection of the closed-loop time constant, (τ{sub c}), a guideline is provided over a broad range of θ/τ ratios on the basis of the peak of maximum uncertainty (M{sub s}). A comparison of the IAE has been conducted for the wide range of θ/τ ratio for the first order time delay process. The proposed method shows minimum IAE in compared to SIMC, while Lee et al. shows poor disturbance rejection in the lag dominant process. In the simulation study, the controllers were tuned to have the same degree of robustness by measuring the M{sub s}, to obtain a reasonable comparison.
Testing the Empirical Shock Arrival Model using Quadrature Observations
Gopalswamy, N; Xie, H; Yashiro, S
2013-01-01
The empirical shock arrival (ESA) model was developed based on quadrature data from Helios (in-situ) and P-78 (remote-sensing) to predict the Sun-Earth travel time of coronal mass ejections (CMEs) [Gopalswamy et al. 2005a]. The ESA model requires earthward CME speed as input, which is not directly measurable from coronagraphs along the Sun-Earth line. The Solar Terrestrial Relations Observatory (STEREO) and the Solar and Heliospheric Observatory (SOHO) were in quadrature during 2010 - 2012, so the speeds of Earth-directed CMEs were observed with minimal projection effects. We identified a set of 20 full halo CMEs in the field of view of SOHO that were also observed in quadrature by STEREO. We used the earthward speed from STEREO measurements as input to the ESA model and compared the resulting travel times with the observed ones from L1 monitors. We find that the model predicts the CME travel time within about 7.3 hours, which is similar to the predictions by the ENLIL model. We also find that CME-CME and CME...
Directory of Open Access Journals (Sweden)
Hans eColonius
2012-08-01
Full Text Available In the crossmodal signals paradigm (CSP participants are instructed to respond to a set of stimuli from different modalities, presented more or less simultaneously, as soon as a stimulus from any modality has been detected. In the focused attention paradigm (FAP, on the other hand, responses should only be made to a stimulus from a pre-defined target modality and stimuli from non-target modalities should be ignored. Whichever paradigm is being applied, a typical result is that responses tend to be faster to crossmodal stimuli than to unimodal stimuli, a phenomenon often referred to as 'crossmodal interaction'. Here we investigate predictions of the time-window-of-integration (TWIN modeling framework previously proposed by the authors. It is shown that TWIN makes specific qualitative and quantitative predictions on how the two paradigms differ with respect to the probability of multisensory integration and the amount of response enhancement, including the effect of stimulus intensity ('inverse effectiveness'. Introducing a decision-theoretic framework for TWIN further allows comparing the two paradigms with respect to the predicted optimal time window size and its dependence on the prior probability that the crossmodal stimulus information refers to the same event. In order to test these predictions, experimental studies that systematically compare crossmodal effects under stimulus conditions that are identical except for the CSP-FAP instruction should be performed in the future.
ERP-Variations on Time Scales Between Hours and Months Derived From GNSS Observations
Weber, R.; Englich, S.; Mendes Cerveira, P.
2007-05-01
Current observations gained by the space geodetic techniques, especially VLBI, GPS and SLR, allow for the determination of Earth Rotation Parameters (ERPs - polar motion, UT1/LOD) with unprecedented accuracy and temporal resolution. This presentation focuses on contributions to the ERP recovery provided by satellite navigation systems (primarily GPS). The IGS (International GNSS Service), for example, currently provides daily polar motion with an accuracy of less than 0.1mas and LOD estimates with an accuracy of a few microseconds. To study more rapid variations in polar motion and LOD we established in a first step a high resolution (hourly resolution) ERP-time series from GPS observation data of the IGS network covering the year 2005. The calculations were carried out by means of the Bernese GPS Software V5.0 considering observations from a subset of 113 fairly stable stations out of the IGS05 reference frame sites. From these ERP time series the amplitudes of the major diurnal and semidiurnal variations caused by ocean tides are estimated. After correcting the series for ocean tides the remaining geodetic observed excitation is compared with variations of atmospheric excitation (AAM). To study the sensitivity of the estimates with respect to the applied mapping function we applied both the widely used NMF (Niell Mapping Function) and the VMF1 (Vienna Mapping Function 1). In addition, based on computations covering two months in 2005, the potential improvement due to the use of additional GLONASS data will be discussed.
Travel Times of Water Derived from Three Naturally Occurring Cosmogenic Radioactive Isotopes
Visser, Ate; Thaw, Melissa; Deinhart, Amanda; Bibby, Richard; Esser, Brad
2017-04-01
Hydrological travel times are studied on scales that span six orders of magnitude, from daily event water in stream flow to pre-Holocene groundwater in wells. Groundwater vulnerability to contamination, groundwater surface water interactions and catchment response are often focused on "modern" water that recharged after the introduction of anthropogenic tritium in precipitation in 1953. Shorter residence times are expected in smaller catchments, resulting in immediate vulnerability to contamination. We studied a small (4.6 km2) alpine (1660-2117 m) catchment in a Mediterranean climate (8 ˚ C, 1200 mm/yr) in the California Sierra Nevada to assess subsurface storage and investigate the response to the recent California drought. 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. Tritium samples (1 L) 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 estimation of stream water age fractions. 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. Estimates of subsurface storage are in agreement with estimates from geophysical studies. Detections of sodium-22
Studying complex tourism systems: a novel approach based on networks derived from a time series
Baggio, Rodolfo
2013-01-01
A tourism destination is a complex dynamic system. As such it requires specific methods and tools to be analyzed and understood in order to better tailor governance and policy measures for steering the destination along an evolutionary growth path. Many proposals have been put forward for the investigation of complex systems and some have been successfully applied to tourism destinations. This paper uses a recent suggestion, that of transforming a time series into a network and analyzes it with the objective of uncovering the structural and dynamic features of a tourism destination. The algorithm, called visibility graph, is simple and its implementation straightforward, yet it is able to provide a number of interesting insights. An example is worked out using data from two destinations: Italy as a country and the island of Elba, one of its most known areas.
Galactic Confinement Time of Iron-Group Cosmic Rays Derived from the {sup 54}Mn Chronometer
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Zaerpoor, K.; Dragowsky, M.R.; Krane, K.S. [Physics Department, Oregon State University, Corvallis, Oregon 97331 (United States); Chan, Y.D.; Isaac, M.C.; Larimer, R.M.; Macchiavelli, A.O.; Macleod, R.W.; Norman, E.B. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); DiGregorio, D.E. [Laboratorio TANDAR-Comision Nacional de Energia Atomica, Buenos Aires, 1429 (Argentina); Hindi, M.M. [Physics Department, Tennessee Technological University, Cookeville, Tennessee 38505 (United States); Miocinovic, P. [Physics Department, University of California, Berkeley, California 94720 (United States)
1997-12-01
The {beta} -decay half-life of {sup 54}Mn is needed to employ this isotope as a cosmic ray chronometer. We have determined the partial half-life of {sup 54}Mn for positron emission by counting a highly purified 35-{mu}Ci source of {sup 54}Mn in GAMMASPHERE to search for the astrophysically interesting {beta}{sup +} decay branch through the observation of coincident positron-annihilation {gamma} rays. A careful analysis of 97hours of source counting and 61hours of background shows a net signal of 24{plus_minus}10 back-to-back 511-511keV coincident events. Based on this result, the branch for this decay mode is (2.2{plus_minus}0.9){times}10{sup {minus}7}{percent} . The implications of this result for the {sup 54}Mn cosmic-ray chronometer problem are discussed. {copyright} {ital 1997} {ital The American Physical Society}
Roman, J.
2015-12-01
The IPCC 5th Assessment found that the predicted warming of 1oC would increase the risk of extreme events such as heat waves, droughts, and floods. Weather extremes, like floods, have shown the vulnerability and susceptibility society has to these extreme weather events, through impacts such as disruption of food production, water supply, health, and damage of infrastructure. This paper examines a new way of near-real time forecasting of precipitation. A 10-year statistical climatological relationship was derived between precipitable water vapor (PWV) and precipitation by using the NASA Atmospheric Infrared Sounder daily gridded PWV product and the NASA Tropical Rainfall Measuring Mission daily gridded precipitation total. Forecasting precipitation estimates in real time is dire for flood monitoring and disaster management. Near real time PWV observations from AIRS on Aqua are available through the Goddard Earth Sciences Data and Information Service Center. In addition, PWV observations are available through direct broadcast from the NASA Suomi-NPP ATMS/CrIS instrument, the operational follow on to AIRS. The derived climatological relationship can be applied to create precipitation estimates in near real time by utilizing the direct broadcasting capabilities currently available in the CONUS region. The application of this relationship will be characterized through case-studies by using near real-time NASA AIRS Science Team v6 PWV products and ground-based SuomiNet GPS to estimate the current precipitation potential; the max amount of precipitation that can occur based on the moisture availability. Furthermore, the potential contribution of using the direct broadcasting of the NUCAPS ATMS/CrIS PWV products will be demonstrated. The analysis will highlight the advantages of applying this relationship in near-real time for flash flood monitoring and risk management. Relevance to the NWS River Forecast Centers will be discussed.
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W. Herbert Wilson
2013-04-01
Full Text Available Using an 18-year dataset of arrival dates of 65 species of Maine migratory breeding birds, I take a deeper view of the data to ask questions about the shapes of the distribution. For each year, most species show a consistent right-skewed pattern of distribution, suggesting that selection is stronger against individuals that arrive too early compared to those that arrive later. Distributions are consistently leptokurtic, indicating a narrow window of optimal arrival dates. Species that arrive earlier in the spring show higher skewness and kurtosis values. Nectarivorous species showed more pronounced skewness. Wintering area did not explain patterns of skewness or kurtosis. Deviations from average temperatures and the North Atlantic Oscillation index explained little variation in skewness and kurtosis. When arrival date distributions are broken down into different medians (e.g., 5% median and 75% median, stronger correlations emerge for portions of the distribution that are adjacent, suggesting species fine-tune the progress of their migration. Interspecific correlations for birds arriving around the same time are stronger for earliest migrants (the 25% median compared to the true median and the 75% median.
Timsit, Edouard; Workentine, Matthew; Schryvers, Anthony B; Holman, Devin B; van der Meer, Frank; Alexander, Trevor W
2016-05-01
Bovine respiratory disease complex (BRDc) is a major cause of morbidity and mortality in beef cattle. There is recent evidence suggesting that the nasopharyngeal microbiota has a key role in respiratory health and disease susceptibility in cattle. However, there is a paucity of knowledge regarding evolution of the nasopharyngeal microbiota when cattle are most likely to develop BRDc (i.e., from weaning to 40days after arrival at a feedlot). The objective was to describe the evolution of the nasopharyngeal microbiota of beef cattle from weaning to 40days after arrival at a feedlot. Deep nasal swabs (DNS) from 30 Angus-cross steers were collected at weaning, on arrival at a feedlot, and at day 40 after arrival. The DNA was extracted from DNS and the hypervariable region V3 of the 16S rRNA gene was amplified and sequenced (Illumina MiSeq platform). Nasopharyngeal microbiota underwent a profound evolution from weaning to arrival at the feedlot and from arrival to day 40, with the abundance of 92 Operational Taxonomic Units (OTUs) significantly changing over time. Mycoplasma (M. dispar and M. bovirhinis) was the most abundant genus in the nasopharynx, accounting for 53% of the total bacterial population. Because an evolving bacterial community may be less capable of resisting colonization by pathogenic bacteria, the instability of the nasopharyngeal microbiota documented in this study might explain why cattle are most likely to be affected with BRDc during the first weeks after weaning and arrival at a feedlot.
Narrowband direction of arrival estimation for antenna arrays
Foutz, Jeffrey
2008-01-01
This book provides an introduction to narrowband array signal processing, classical and subspace-based direction of arrival (DOA) estimation with an extensive discussion on adaptive direction of arrival algorithms. The book begins with a presentation of the basic theory, equations, and data models of narrowband arrays. It then discusses basic beamforming methods and describes how they relate to DOA estimation. Several of the most common classical and subspace-based direction of arrival methods are discussed. The book concludes with an introduction to subspace tracking and shows how subspace tr
Concept of Operations for Interval Management Arrivals and Approach
Hicok, Daniel S.; Barmore, Bryan E.
2016-01-01
This paper presents the concept of operations for interval management operations to be deployed in the US National Airspace System (NAS) by the Federal Aviation Administration (FAA) after 2020. The use of interval management operations is described that begin in en route airspace and continue to a termination point inside the arrival terminal area, in a terminal environment that includes other arrival management tools such as arrival metering, Ground-based Interval Management - Spacing (GIM-S), and Terminal Sequencing and Spacing (TSAS). The roles of Air Traffic Controllers and Flight Crews and the ground automation tools that are used by Air Traffic Controllers to enable the primary operation and variations are described.
Prathap Reddy, K.
2016-11-01
An ‘electrostatic bathtub potential’ is defined and analytical expressions for the time period and amplitude of charged particles in this potential are obtained and compared with simulations. These kinds of potentials are encountered in linear electrostatic ion traps, where the potential along the axis appears like a bathtub. Ion traps are used in basic physics research and mass spectrometry to store ions; these stored ions make oscillatory motion within the confined volume of the trap. Usually these traps are designed and studied using ion optical software, but in this work the bathtub potential is reproduced by making two simple modifications to the harmonic oscillator potential. The addition of a linear ‘k 1|x|’ potential makes the simple harmonic potential curve steeper with a sharper turn at the origin, while the introduction of a finite-length zero potential region at the centre reproduces the flat region of the bathtub curve. This whole exercise of modelling a practical experimental situation in terms of a well-known simple physics problem may generate interest among readers.
Rębilas, Krzysztof
2014-01-01
Starting from the classical Newton's second law which, according to our assumption, is valid in any instantaneous inertial rest frame of body that moves in Minkowskian space-time we get the relativistic equation of motion $\\vec{F}=d\\vec{p}/dt$, where $\\vec{p}$ is the relativistic momentum. The relativistic momentum is then derived without referring to any additional assumptions concerning elastic collisions of bodies. Lorentz-invariance of the relativistic law is proved without tensor formalism. Some new method of force transformation is also presented.
Zhang, Xing; Herbert, John M.
2015-02-01
We revisit the formalism for analytic derivative couplings between excited states in time-dependent density functional theory (TDDFT). We derive and implement these couplings using quadratic response theory, then numerically compare this response-theory formulation to couplings implemented previously based on a pseudo-wavefunction formalism and direct differentiation of the Kohn-Sham determinant. Numerical results, including comparison to full configuration interaction calculations, suggest that the two approaches perform equally well for many molecular systems, provided that the underlying DFT method affords accurate potential energy surfaces. The response contributions are found to be important for certain systems with high symmetry, but can be calculated with only a moderate increase in computational cost beyond what is required for the pseudo-wavefunction approach. In the case of spin-flip TDDFT, we provide a formal proof that the derivative couplings obtained using response theory are identical to those obtained from the pseudo-wavefunction formulation, which validates our previous implementation based on the latter formalism.
Zhang, Xing; Herbert, John M
2015-02-14
We revisit the formalism for analytic derivative couplings between excited states in time-dependent density functional theory (TDDFT). We derive and implement these couplings using quadratic response theory, then numerically compare this response-theory formulation to couplings implemented previously based on a pseudo-wavefunction formalism and direct differentiation of the Kohn-Sham determinant. Numerical results, including comparison to full configuration interaction calculations, suggest that the two approaches perform equally well for many molecular systems, provided that the underlying DFT method affords accurate potential energy surfaces. The response contributions are found to be important for certain systems with high symmetry, but can be calculated with only a moderate increase in computational cost beyond what is required for the pseudo-wavefunction approach. In the case of spin-flip TDDFT, we provide a formal proof that the derivative couplings obtained using response theory are identical to those obtained from the pseudo-wavefunction formulation, which validates our previous implementation based on the latter formalism.
FORECASTING THE NUMBER OF SPORT TOURISM ARRIVALS IN SOUTHWEST BULGARIA
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Preslav Mihaylov Dimitrov
2016-12-01
Full Text Available This paper presents an application of some forecasting methods concerning sport tourism arrivals in Southwest Bulgaria: linear trend forecasting, double exponential forecasting (Holt’s method, triple exponential forecasting (the Holt-Winters Method, and the ARIMA method. A specially designed model for estimating the weight coefficient needed for determining the size of the sport tourism’s sector in the time series of the available data and in the forecast values is presented. In order to test the forecasting methods and produce forecasts up to the year 2030, a time series and past period predictions have been constructed based on statistical records since 1964. Several major problems in the application of the exponential smoothing methods for the purpose of the long-run forecasting and the needs of the sport tourism subsector of Bulgaria tourism industry are addressed. These problems include (a finding a suitable general indicator, (b calculating short-term and long-term forecasts, (c comparing the results of the forecast techniques on the basis of the errors in the forecasts, (d estimating the size of the sport tourism in Southwest Bulgaria in certain terms so that the forecast(s of the above-mentioned general indicator could be particularized especially for examined sub-sector and region. The results from the different forecasting methods and techniques are presented and conclusions are drawn regarding the reliability of the forecasts.
Liang, Xianrui; Han, Xiaomei
2015-09-15
Synthetic and natural coumarin derivatives possess a wide range of biological activities. Fragmentation pathway studies are important in identifying both naturally occurring coumarins and synthetic coumarins with novel structures and properties. The fragmentation pathways of eleven coumarin derivatives are investigated by electrospray ionization (ESI) ion-trap mass spectrometry (ESI-ITMS(n) ) and ESI quadrupole time-of-flight mass spectrometry (QTOFMS) in positive mode. Compounds 1-9 in this study were newly synthesized in our laboratory. Compounds 10 and 11 were isolated from the root of Zanthoxylum armatum. The major fragmentation pathways for 11 coumarin derivatives are greatly affected by the heterocyclic ring structures and the side-chain substituents. Typical losses of small neutral molecules, such as CH3 CH2 OH, CH2 =CH2 , CO, and H2 O, are observed for compounds 1-5. Compounds 6-9 share similar fragmentation pathways through losses of CO, aromatic rings, and the coumarin skeleton. The main product ions at m/z 205, 219, and 220 observed for compounds 10 and 11 are produced by the loss of C5 H12 O2 , C4 H10 O2 , and the C4 H9 O2 radical, respectively. The fragmentation pathways of 11 coumarin derivatives are elucidated based on ITMS(n) and QTOFMS spectral data. Differences in the structures of the heterocyclic rings and side-chain substituents strongly affect the fragmentation pathways of the coumarins. The present results will facilitate further research into the fragmentation pathways and structural characterization of these classes of compounds with diverse structures. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.
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K. Lesley eSzostek
2015-04-01
Full Text Available Changes in the timing of migratory events have been observed recently in many migratory species, most likely in response to climatic change. In the common tern Sterna hirundo we examined such changes in spring arrival date and body mass based on a 19 year individual-based longitudinal data from a transponder marked colony from 1994 - 2012. Although no long-term trend was observed in either trait, strong inter-annual and age-specific variation in arrival date and mass was evident. We investigated whether environmental factors such as (i global climate phenomena North Atlantic and Southern Oscillation Indices NAOI and SOI, or (ii local factors, such as food abundance in the wintering and breeding area, represented by fish stock or marine primary productivity, could explain this variation. We found that 2-year-old birds on their first spring migration advanced arrival relative to spring NAOI and delayed arrival relative to sprat Sprattus sprattus abundance. The arrival date of 3-year-olds also advanced in relation to NAOI and delayed in relation to winter SOI. In contrast, adults delayed arrival with NAOI and advanced relative to SOI. Within age groups, earlier annual arrival coincided with higher mass, indicating that a fast and/or early migration did not come at a cost to body condition. Changes in arrival mass relative to environmental covariates were found only in 2-year-olds on their first spring migration: in these birds arrival mass was positively related to herring Clupea harengus and sprat abundance in the breeding area as well as spring NAOI and negatively related to SOI. In conclusion, traits related to migration of common terns were linked with environmental conditions, but showed no long-term trends over the past two decades. Age-related differences were marked, suggesting that common terns might be subject to differing environmental constraints or respond differently to conditions during their annual cycle depending on age.
Algorithm Indicating Moment of P-Wave Arrival Based on Second-Moment Characteristic
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Jakub Sokolowski
2016-01-01
Full Text Available The moment of P-wave arrival can provide us with many information about the nature of a seismic event. Without adequate knowledge regarding the onset moment, many properties of the events related to location, polarization of P-wave, and so forth are impossible to receive. In order to save time required to indicate P-wave arrival moment manually, one can benefit from automatic picking algorithms. In this paper two algorithms based on a method finding a regime switch point are applied to seismic event data in order to find P-wave arrival time. The algorithms are based on signals transformed via a basic transform rather than on raw recordings. They involve partitioning the transformed signal into two separate series and fitting logarithm function to the first subset (which corresponds to pure noise and therefore it is considered stationary, exponent or power function to the second subset (which corresponds to nonstationary seismic event, and finding the point at which these functions best fit the statistic in terms of sum of squared errors. Effectiveness of the algorithms is tested on seismic data acquired from O/ZG “Rudna” underground copper ore mine with moments of P-wave arrival initially picked by broadly known STA/LTA algorithm and then corrected by seismic station specialists. The results of proposed algorithms are compared to those obtained using STA/LTA.
Zika Arrived in Florida At Least Four Different Ways
... page: https://medlineplus.gov/news/fullstory_165906.html Zika Arrived in Florida at Least Four Different Ways ... WEDNESDAY, May 24, 2017 (HealthDay News) -- The 2016 Zika outbreak in Florida wasn't due to a ...
U.S. Environmental Protection Agency — This database processes approximately 3,000 Notice of Arrival (NOA) reporting forms from importers and exporters of pesticide products. This is an electronic version...
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Kuda Nageswara Rao
2010-07-01
Full Text Available This paper deals with the performance evaluation of a two node communication network with dynamic bandwidth allocation and modified phase type transmission having bulk arrivals. The performance of the statistical multiplexing is measured by approximating with the compound Poisson process and the transmission completions with Poisson processes. It is further assumed that the transmission rate at each node are adjusted depending upon the content of the buffer which is connected to it. The packets transmitted through the first node may be forwarded to the buffer connected to the second node or get terminated with certain probabilities. The performance measures of the network like, mean content of the buffers, mean delays, throughput, transmitter utilization etc. are derived explicitly under transient conditions. Sensitivity analysis with respect to the parameters is also carried through numerical illustration. It is observed that the dynamic bandwidth allocation and batch size distribution of arrivals has a tremendous influence on the performance measures.
Diversifying the picture: indigenous responses to European arrival in Cuba
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Marcos Martinón-Torres
2007-09-01
Full Text Available There is a growing interest in cultural contact between indigenous peoples and Europeans following their arrival in the New World. In this article the authors explore local responses to European arrival in Cuba, through analysis of metalwork found in indigenous graves. These studies demonstrate that the local communities valued particular metals quite differently from the Europeans, as the imported materials were incorporated into pre-existing symbolic systems relating to sacred power.
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Kim, Song Hyun; Woo, Myeong Hyun; Shin, Chang Ho [Hanyang University, Seoul (Korea, Republic of); Pyeon, Cheol Ho [Kyoto University, Osaka (Japan)
2015-10-15
In this study, a new balance equation to overcome the problems generated by the previous methods is proposed using source-based balance equation. And then, a simple problem is analyzed with the proposed method. In this study, a source-based balance equation with the time dependent fission kernel was derived to simplify the kinetics equation. To analyze the partial variations of reactor characteristics, two representative methods were introduced in previous studies; (1) quasi-statics method and (2) multipoint technique. The main idea of quasistatics method is to use a low-order approximation for large integration times. To realize the quasi-statics method, first, time dependent flux is separated into the shape and amplitude functions, and shape function is calculated. It is noted that the method has a good accuracy; however, it can be expensive as a calculation cost aspect because the shape function should be fully recalculated to obtain accurate results. To improve the calculation efficiency, multipoint method was proposed. The multipoint method is based on the classic kinetics equation with using Green's function to analyze the flight probability from region r' to r. Those previous methods have been used to analyze the reactor kinetics analysis; however, the previous methods can have some limitations. First, three group variables (r{sub g}, E{sub g}, t{sub g}) should be considered to solve the time dependent balance equation. This leads a big limitation to apply large system problem with good accuracy. Second, the energy group neutrons should be used to analyze reactor kinetics problems. In time dependent problem, neutron energy distribution can be changed at different time. It can affect the change of the group cross section; therefore, it can lead the accuracy problem. Third, the neutrons in a space-time region continually affect the other space-time regions; however, it is not properly considered in the previous method. Using birth history of the
Transient Solution to an infinite Server Queue with Varying Arrival and Departure Rate
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A. A. El-Sherbiny
2010-01-01
Full Text Available Problem statement: In many potential application of queueing theory, the transient solution of queueing system is important. Approach: This study presented the transient solution for infinite server queues with Poisson arrivals and exponential service times when the parameters of both distributions are allowed to vary with time. Based on generating functions technique which results in a simple differential equation. Using the properties of Bessel functions in the solution of this differential equation, the solution of an infinite server queues can be given in simple form. Results: The researcher obtained the transient solution an infinite server queues with Poisson arrivals and exponential service times when the parameters of both distributions are allowed to vary with time and prove that some past results are special case from his results. Conclusion: These results indicated that the probabilities can be extracted in a direct way.
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Cochrane, Alexander P. [Aerospace Engineering Department, University of Glasgow, University Avenue, Glasgow, Lanarkshire (United Kingdom); Merrett, Craig G. [Mechanical and Aerospace Engineering Department, Carleton Univ., 1125 Col. By Dr., Ottawa, ON (Canada); Hilton, Harry H. [Aerospace Engineering Department in the College of Engineering and Private Sector Program Division at the National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, 104 South Wright Street, Urbana, IL 61801 (United States)
2014-12-10
The advent of new structural concepts employing composites in primary load carrying aerospace structures in UAVs, MAVs, Boeing 787s, Airbus A380s, etc., necessitates the inclusion of flexibility as well as viscoelasticity in static structural and aero-viscoelastic analyses. Differences and similarities between aeroelasticity and aero-viscoelasticity have been investigated in [2]. An investigation is undertaken as to the dependence and sensitivity of aerodynamic and stability derivatives to elastic and viscoelastic structural flexibility and as to time dependent flight and maneuver velocities. Longitudinal, lateral and directional stabilities are investigated. It has been a well established fact that elastic lifting surfaces are subject to loss of control effectiveness and control reversal at certain flight speeds, which depend on aerodynamic, structural and material properties [5]. Such elastic analyses are extended to linear viscoelastic materials under quasi-static, dynamic, and sudden and gradual loading conditions. In elastic wings one of the critical static parameters is the velocity at which control reversal takes place (V{sub REV}{sup E}). Since elastic formulations constitute viscoelastic initial conditions, viscoelastic reversal may occur at speeds V{sub REV<}{sup ≧}V{sub REV}{sup E}, but furthermore does so in time at 0 < t{sub REV} ≤ ∞. The influence of the twin effects of viscoelastic and elastic materials and of variable flight velocities on longitudinal, lateral, directional and spin stabilities are also investigated. It has been a well established fact that elastic lifting surfaces are subject to loss of control effectiveness and control reversal at certain flight speeds, which depend on aerodynamic, structural and material properties [5]. Such elastic analyses are here extended to linear viscoelastic materials under quasi-static, dynamic, and sudden and gradual loading conditions. In elastic wings the critical parameter is the velocity at