Stochastic kinetics of a single headed motor protein: dwell time distribution of KIF1A
Garai, Ashok
2010-01-01
KIF1A, a processive single headed kinesin superfamily motor, hydrolyzes Adenosine triphosphate (ATP) to move along a filamentous track called microtubule. The stochastic movement of KIF1A on the track is characterized by an alternating sequence of pause and translocation. The sum of the durations of pause and the following translocation defines the dwell time at the binding site on the microtubule. Using the NOSC model (Nishinari et. al. PRL, {\\bf 95}, 118101 (2005)), which captures the Brownian ratchet mechanism of individual KIF1A along with its biochemical cycle, we systematically derive an analytical expression for the dwell time distribution. In principle, our theoretical prediction can be tested by carrying out single-molecule experiments with adequate spatio-temporal resolution.
Sharma, Ajeet K
2010-01-01
Ribosome is a molecular machine that polymerizes a protein where the sequence of the amino acid subunits of the protein is dictated by the sequence of codons (triplets of nucleotide subunits) on a messenger RNA (mRNA) that serves as the template. The ribosome is a molecular motor that utilizes the template mRNA strand also as the track. Thus, in each step the ribosome moves forward by one codon and, simultaneously, elongates the protein by one amino acid. We present a theoretical model that captures most of the main steps in the mechano-chemical cycle of a ribosome. The stochastic movement of the ribosome consists of an alternating sequence of pause and translocation; the sum of the durations of a pause and the following translocation is defined as the time of dwell of the ribosome at the corresponding codon. We present an analytical calculation of the distribution of the dwell times of a ribosome in our model. Our theoretical prediction is consistent with the experimental results reported in the literature.
Sharma, Ajeet K; Chowdhury, Debashish
2011-04-01
Ribosome is a molecular machine that polymerizes a protein where the sequence of the amino acid residues, the monomers of the protein, is dictated by the sequence of codons (triplets of nucleotides) on a messenger RNA (mRNA) that serves as the template. The ribosome is a molecular motor that utilizes the template mRNA strand also as the track. Thus, in each step the ribosome moves forward by one codon and, simultaneously, elongates the protein by one amino acid. We present a theoretical model that captures most of the main steps in the mechanochemical cycle of a ribosome. The stochastic movement of the ribosome consists of an alternating sequence of pause and translocation; the sum of the durations of a pause and the following translocation is the time of dwell of the ribosome at the corresponding codon. We derive the analytical expression for the distribution of the dwell times of a ribosome in our model. Wherever experimental data are available, our theoretical predictions are consistent with those results. We suggest appropriate experiments to test the new predictions of our model, particularly the effects of the quality control mechanism of the ribosome and that of their crowding on the mRNA track.
Directory of Open Access Journals (Sweden)
Ping Xie
2015-10-01
Full Text Available Proteins in the cell are synthesized by a ribosome translating the genetic information encoded on the single-stranded messenger RNA (mRNA. It has been shown that the ribosome can also translate through the duplex region of the mRNA by unwinding the duplex. Here, based on our proposed model of the ribosome translation through the mRNA duplex we study theoretically the distribution of dwell times of the ribosome translation through the mRNA duplex under the effect of a pulling force externally applied to the ends of the mRNA to unzip the duplex. We provide quantitative explanations of the available single molecule experimental data on the distribution of dwell times with both short and long durations, on rescuing of the long paused ribosomes by raising the pulling force to unzip the duplex, on translational arrests induced by the mRNA duplex and Shine-Dalgarno(SD-like sequence in the mRNA. The functional consequences of the pauses or arrests caused by the mRNA duplex and the SD sequence are discussed and compared with those obtained from other types of pausing, such as those induced by “hungry” codons or interactions of specific sequences in the nascent chain with the ribosomal exit tunnel.
Modelling of Attentional Dwell Time
DEFF Research Database (Denmark)
Petersen, Anders; Kyllingsbæk, Søren; Bundesen, Claus
2009-01-01
into the temporal domain. In the neural interpretation of TVA (NTVA; Bundesen, Habekost and Kyllingsbæk, 2005), processing resources are implemented as allocation of cortical cells to objects in the visual field. A feedback mechanism is then used to keep encoded objects in VSTM alive. The proposed model...... of attentional dwell time extends these mechanisms by proposing that the processing resources (cells) already engaged in a feedback loop (i.e. allocated to an object) are locked in VSTM and therefore cannot be allocated to other objects in the visual field before the encoded object has been released...
Occurrence and Distribution of Cave Dwelling Frogs of Peninsular India
Directory of Open Access Journals (Sweden)
Jayant Biswas
2014-10-01
Full Text Available The life in subterranean caves always needs a high degree of biological adaptability, due to its unusual ecosystem. The cave dwelling species usually get selected from preadapted biological traits for cave life. The cave dwelling tendencies in frog are very uncommon. Majority of reported cave frogs usually prefer cave for temporary shelter. In India, the biospeleological inventory is still in its primary stage. Till date no serious attempt has been taken to understand the cave dwelling habitat for any frog in India. Inspite of it, in India time to time various reports on natural histories of anurans reveal its cave dwelling tendencies. On the basis of personal observations and available literature in this report I have documented the occurrences and distributions of five cave dwelling frogs of India. Common biological traits from all the established cave frogs, which could be referred as preadapted for cave life, have been discussed. Further, the possible threats and IUCN status of each discussed species has been highlighted.
Yet one more dwell time algorithm
Haberl, Alexander; Rascher, Rolf
2017-06-01
The current demand of even more powerful and efficient microprocessors, for e.g. deep learning, has led to an ongoing trend of reducing the feature size of the integrated circuits. These processors are patterned with EUV-lithography which enables 7 nm chips [1]. To produce mirrors which satisfy the needed requirements is a challenging task. Not only increasing requirements on the imaging properties, but also new lens shapes, such as aspheres or lenses with free-form surfaces, require innovative production processes. However, these lenses need new deterministic sub-aperture polishing methods that have been established in the past few years. These polishing methods are characterized, by an empirically determined TIF and local stock removal. Such a deterministic polishing method is ion-beam-figuring (IBF). The beam profile of an ion beam is adjusted to a nearly ideal Gaussian shape by various parameters. With the known removal function, a dwell time profile can be generated for each measured error profile. Such a profile is always generated pixel-accurately to the predetermined error profile, with the aim always of minimizing the existing surface structures up to the cut-off frequency of the tool used [2]. The processing success of a correction-polishing run depends decisively on the accuracy of the previously computed dwell-time profile. So the used algorithm to calculate the dwell time has to accurately reflect the reality. But furthermore the machine operator should have no influence on the dwell-time calculation. Conclusively there mustn't be any parameters which have an influence on the calculation result. And lastly it should take a minimum of machining time to get a minimum of remaining error structures. Unfortunately current dwell time algorithm calculations are divergent, user-dependent, tending to create high processing times and need several parameters to bet set. This paper describes an, realistic, convergent and user independent dwell time algorithm. The
Critical dwell time of switched linear systems
Institute of Scientific and Technical Information of China (English)
Lijun ZHANG; Chunwen LI
2006-01-01
In this paper, we consider the relation between the switching dwell time and the stabilization of switched linear control systems. First of all, a concept of critical dwell time is given for switched linear systems without control inputs, and the critical dwell time is taken as an arbitrary given positive constant for a switched linear control systems with controllable switching models. Secondly, when a switched linear system has many stabilizable switching models, the problem of stabilization of the overall system is considered. An on-line feedback control is designed such that the overall system is asymptotically stabilizable under switching laws which depend only on those of uncontrollable subsystems of the switching models. Finally, when a switched system is partially controllable (While some switching models are probably unstabilizable), an on-line feedback control and a cyclic switching strategy are designed such that the overall system is asymptotically stabilizable if all switching models of this uncontrollable subsystems are asymptotically stable. In addition,algorithms for designing switching laws and controls are presented.
The effect of masking in the attentional dwell time paradigm
DEFF Research Database (Denmark)
Petersen, Anders
2009-01-01
A temporary functional blindness to the second of two spatially separated targets has been identified in numerous studies of temporal visual attention. This effect is known as attentional dwell time and is maximal 200 to 500 ms after presentation of the first target (e.g. Duncan, Ward, Shapiro......, 1994). In most studies of attentional dwell time, two masked targets have been used. Moore et al. (1996) have criticised the masking of the first target when measuring the attentional dwell time, finding a shorter attentional dwell time when the first mask was omitted. In the presented work, the effect...... an impairment of the second target. Hence, the attentional dwell time may be a combined effect arising from attending to both the first target and its mask....
Vertical Distribution of Air Temperatures in Heated Dwelling Rooms
Šikula, Ondřej
2007-01-01
The paper presents an experimental and theoretic research on one of factors influencing the indoor climate in dwelling rooms heated by heating systems, the vertical distribution of temperatures. The paper summarizes results from simulation of the room heated by a gas space heater and a plate radiator. Among main factors causing unfavorable distribution of temperatures in a room belong insufficient elimination of cold dropping airflows and high temperature of heating air. The paper presents...
Distributed interactive communication in simulated space-dwelling groups.
Brady, Joseph V; Hienz, Robert D; Hursh, Steven R; Ragusa, Leonard C; Rouse, Charles O; Gasior, Eric D
2004-03-01
This report describes the development and preliminary application of an experimental test bed for modeling human behavior in the context of a computer generated environment to analyze the effects of variations in communication modalities, incentives and stressful conditions. In addition to detailing the methodological development of a simulated task environment that provides for electronic monitoring and recording of individual and group behavior, the initial substantive findings from an experimental analysis of distributed interactive communication in simulated space dwelling groups are described. Crews of three members each (male and female) participated in simulated "planetary missions" based upon a synthetic scenario task that required identification, collection, and analysis of geologic specimens with a range of grade values. The results of these preliminary studies showed clearly that cooperative and productive interactions were maintained between individually isolated and distributed individuals communicating and problem-solving effectively in a computer-generated "planetary" environment over extended time intervals without benefit of one another's physical presence. Studies on communication channel constraints confirmed the functional interchangeability between available modalities with the highest degree of interchangeability occurring between Audio and Text modes of communication. The effects of task-related incentives were determined by the conditions under which they were available with Positive Incentives effectively attenuating decrements in performance under stressful time pressure.
Balvert, M.; Gorissen, B.L.; den Hertog, D.; Hoffmann, A.L.
2015-01-01
Inverse planning algorithms for dwell time optimisation in interstitial high-dose-rate (HDR) brachytherapy may produce solutions with large dwell time variations within catheters, which may result in undesirable selective high-dose subvolumes. Extending the dwell time optimisation model with a dwell
Predictive modelling of running and dwell times in railway traffic
Kecman, P.; Goverde, R.M.P.
2015-01-01
Accurate estimation of running and dwell times is important for all levels of planning and control of railway traffic. The availability of historical track occupation data with a high degree of granularity inspired a data-driven approach for estimating these process times. In this paper we present
Jia, Hongwei; Zhao, Jun
2016-08-01
The output regulation problem of switched linear multi-agent systems with stabilisable and unstabilisable subsystems is investigated in this paper. A sufficient condition for the solvability of the problem is given. Owing to the characteristics of switched multi-agent systems, even if each agent has its own dwell time, the multi-agent systems, if viewed as an overall switched system, may not have a dwell time. To overcome this difficulty, we present a new approach, called an agent-dependent average dwell time method. Due to the limited information exchange between agents, a distributed dynamic observer network for agents is provided. Further, a distributed dynamic controller based on observer is designed. Finally, simulation results show the effectiveness of the proposed solutions.
Estimation of train dwell time at short stops based on track occupation event data
Li, D.; Daamen, W.; Goverde, R.M.P.
2015-01-01
Train dwell time is one of the most unpredictable components of railway operations mainly due to the varying volumes of alighting and boarding passengers. For reliable estimations of train running times and route conflicts on main lines it is however necessary to obtain accurate estimations of dwell
Directory of Open Access Journals (Sweden)
Zhibin Jiang
2015-04-01
Full Text Available Understanding the nature of rail transit dwell time has potential benefits for both the users and the operators. Crowded passenger trains cause longer dwell times and may prevent some passengers from boarding the first available train that arrives. Actual dwell time and the process of passenger alighting and boarding are interdependent through the sequence of train stops and propagated delays. A comprehensive and feasible dwell time simulation model was developed and optimized to address the problems associated with scheduled timetables. The paper introduces the factors that affect dwell time in urban rail transit systems, including train headway, the process and number of passengers alighting and boarding the train, and the inability of train doors to properly close the first time because of overcrowded vehicles. Finally, based on a time-driven micro-simulation system, Shanghai rail transit Line 8 is used as an example to quantify the feasibility of scheduled dwell times for different stations, directions of travel and time periods, and a proposed dwell time during peak hours in several crowded stations is presented according to the simulation results.
Distributed communication and psychosocial performance in simulated space dwelling groups
Hienz, R. D.; Brady, J. V.; Hursh, S. R.; Ragusa, L. C.; Rouse, C. O.; Gasior, E. D.
2005-05-01
The present report describes the development and application of a distributed interactive multi-person simulation in a computer-generated planetary environment as an experimental test bed for modeling the human performance effects of variations in the types of communication modes available, and in the types of stress and incentive conditions underlying the completion of mission goals. The results demonstrated a high degree of interchangeability between communication modes (audio, text) when one mode was not available. Additionally, the addition of time pressure stress to complete tasks resulted in a reduction in performance effectiveness, and these performance reductions were ameliorated via the introduction of positive incentives contingent upon improved performances. The results obtained confirmed that cooperative and productive psychosocial interactions can be maintained between individually isolated and dispersed members of simulated spaceflight crews communicating and problem-solving effectively over extended time intervals without the benefit of one another's physical presence.
Balvert, Marleen; Gorissen, Bram L.; den Hertog, Dick; Hoffmann, Aswin L.
2015-01-01
Inverse planning algorithms for dwell time optimisation in interstitial high-dose-rate (HDR) brachytherapy may produce solutions with large dwell time variations within catheters, which may result in undesirable selective high-dose subvolumes. Extending the dwell time optimisation model with a dwell time modulation restriction (DTMR) that limits dwell time differences between neighboring dwell positions has been suggested to eliminate this problem. DTMRs may additionally reduce the sensitivity for uncertainties in dwell positions that inevitably result from catheter reconstruction errors and afterloader source positioning inaccuracies. This study quantifies the reduction of high-dose subvolumes and the robustness against these uncertainties by applying a DTMR to template-based prostate HDR brachytherapy implants. Three different DTMRs were consecutively applied to a linear dose-based penalty model (LD) and a dose-volume based model (LDV), both obtained from literature. The models were solved with DTMR levels ranging from no restriction to uniform dwell times within catheters in discrete steps. Uncertainties were simulated on clinical cases using in-house developed software, and dose-volume metrics were calculated in each simulation. For the assessment of high-dose subvolumes, the dose homogeneity index (DHI) and the contiguous dose volume histogram were analysed. Robustness was measured by the improvement of the lowest D90% of the planning target volume (PTV) observed in the simulations. For (LD), a DTMR yields an increase in DHI of approximately 30% and reduces the size of the largest high-dose volume by 2-5 cc. However, this comes at a cost of a reduction in D90% of the PTV of 10%, which often implies that it drops below the desired minimum of 100%. For (LDV), none of the DTMRs were able to improve high-dose volume measures. DTMRs were not capable of improving robustness of PTV D90% against uncertainty in dwell positions for both models.
A Fuzzy Logic-Based Approach for Estimation of Dwelling Times of Panama Metro Stations
Directory of Open Access Journals (Sweden)
Aranzazu Berbey Alvarez
2015-04-01
Full Text Available Passenger flow modeling and station dwelling time estimation are significant elements for railway mass transit planning, but system operators usually have limited information to model the passenger flow. In this paper, an artificial-intelligence technique known as fuzzy logic is applied for the estimation of the elements of the origin-destination matrix and the dwelling time of stations in a railway transport system. The fuzzy inference engine used in the algorithm is based in the principle of maximum entropy. The approach considers passengers’ preferences to assign a level of congestion in each car of the train in function of the properties of the station platforms. This approach is implemented to estimate the passenger flow and dwelling times of the recently opened Line 1 of the Panama Metro. The dwelling times obtained from the simulation are compared to real measurements to validate the approach.
Huang, Chuangxia; Cao, Jie; Cao, Jinde
2016-10-01
This paper addresses the exponential stability of switched cellular neural networks by using the mode-dependent average dwell time (MDADT) approach. This method is quite different from the traditional average dwell time (ADT) method in permitting each subsystem to have its own average dwell time. Detailed investigations have been carried out for two cases. One is that all subsystems are stable and the other is that stable subsystems coexist with unstable subsystems. By employing Lyapunov functionals, linear matrix inequalities (LMIs), Jessen-type inequality, Wirtinger-based inequality, reciprocally convex approach, we derived some novel and less conservative conditions on exponential stability of the networks. Comparing to ADT, the proposed MDADT show that the minimal dwell time of each subsystem is smaller and the switched system stabilizes faster. The obtained results extend and improve some existing ones. Moreover, the validness and effectiveness of these results are demonstrated through numerical simulations.
Foster, B. K.; Beese, A. M.; Keist, J. S.; McHale, E. T.; Palmer, T. A.
2017-09-01
Path planning in additive manufacturing (AM) processes has an impact on the thermal histories experienced at discrete locations in simple and complex AM structures. One component of path planning in directed energy deposition is the time required for the laser or heat source to return to a given location to add another layer of material. As structures become larger and more complex, the length of this interlayer dwell time can significantly impact the resulting thermal histories. The impact of varying dwell times between 0 and 40 seconds on the microstructural and mechanical properties of Inconel® 625 and Ti-6Al-4V builds has been characterized. Even though these materials display different microstructures and solid-state phase transformations, the addition of an interlayer dwell generally led to a finer microstructure in both materials that impacted the resulting mechanical properties. With the addition of interlayer dwell times up to 40 seconds in the Inconel® 625 builds, finer secondary dendrite arm spacing values, produced by changes in the thermal history, correspond to increased yield and tensile strengths. These mechanical properties did not appear to change significantly, however, for dwell times greater than 20 seconds in the Inconel® 625 builds, indicating that longer dwell times have a minimal impact. The addition of interlayer dwell times in Ti-6Al-4V builds resulted in a slight decrease in the measured alpha lath widths and a much more noticeable decrease in the width of prior beta grains. In addition, the yield and tensile values continued to increase, nearly reaching the values observed in the rolled plate substrate material with dwell times up to 40 seconds.
Finite-frequency model reduction of continuous-time switched linear systems with average dwell time
Ding, Da-Wei; Du, Xin
2016-11-01
This paper deals with the model reduction problem of continuous-time switched linear systems with finite-frequency input signals. The objective of the paper is to propose a finite-frequency model reduction method for such systems. A finite-frequency ? performance index is first defined in frequency domain, and then a finite-frequency performance analysis condition is derived by Parseval's theorem. Combined with the average dwell time approach, sufficient conditions for the existence of exponentially stable reduced-order models are derived. An algorithm is proposed to construct the desired reduced-order models. The effectiveness of the proposed method is illustrated by a numerical example.
An ELM-Based Approach for Estimating Train Dwell Time in Urban Rail Traffic
Directory of Open Access Journals (Sweden)
Wen-jun Chu
2015-01-01
Full Text Available Dwell time estimation plays an important role in the operation of urban rail system. On this specific problem, a range of models based on either polynomial regression or microsimulation have been proposed. However, the generalization performance of polynomial regression models is limited and the accuracy of existing microsimulation models is unstable. In this paper, a new dwell time estimation model based on extreme learning machine (ELM is proposed. The underlying factors that may affect urban rail dwell time are analyzed first. Then, the relationships among different factors are extracted and modeled by ELM neural networks, on basis of which an overall estimation model is proposed. At last, a set of observed data from Beijing subway is used to illustrate the proposed method and verify its overall performance.
Evaluating Distributed Timing Constraints
DEFF Research Database (Denmark)
Kristensen, C.H.; Drejer, N.
1994-01-01
In this paper we describe a solution to the problem of implementing time-optimal evaluation of timing constraints in distributed real-time systems.......In this paper we describe a solution to the problem of implementing time-optimal evaluation of timing constraints in distributed real-time systems....
Influence of overloads on dwell time fatigue crack growth in Inconel 718
Energy Technology Data Exchange (ETDEWEB)
Saarimäki, Jonas, E-mail: jonas.saarimaki@liu.se [Division of Engineering Materials, Department of Management and Engineering, Linköping University, SE-58183 Linköping (Sweden); Moverare, Johan [Division of Engineering Materials, Department of Management and Engineering, Linköping University, SE-58183 Linköping (Sweden); Siemens Industrial Turbomachinery AB, Materials Technology, SE-61283 Finspång (Sweden); Eriksson, Robert; Johansson, Sten [Division of Engineering Materials, Department of Management and Engineering, Linköping University, SE-58183 Linköping (Sweden)
2014-08-26
Inconel 718 is one of the most commonly used superalloys for high temperature applications in gasturbines and aeroengines and is for example used for components such as turbine discs. Turbine discs can be subjected to temperatures up to ∼700 °C towards the outer radius of the disc. During service, the discs might start to develop cracks due to fatigue and long dwell times. Additionally, temperature variations during use can lead to large thermal transients during start-up and shutdown which can lead to overload peaks in the normal dwell time cycle. In this study, tests at 550 °C with an overload prior to the start of each dwell time, have been performed. The aim of the investigation was to get a better understanding of the effects of overloads on the microstructure and crack mechanisms. The microstructure was studied using electron channelling contrast imaging (ECCI). The image analysis toolbox in Matlab was used on cross sections of the cracks to quantify: crack length, branch length, and the number of branches in each crack. It was found that the amount of crack branching increases with an increasing overload and that the branch length decreases with an increasing overload. When the higher overloads were applied, the dwell time effect was almost cancelled out. There is a strong tendency for an increased roughness of the crack path with an increasing crack growth rate.
Abad-Álvaro, Isabel; Peña-Vázquez, Elena; Bolea, Eduardo; Bermejo-Barrera, Pilar; Castillo, Juan R; Laborda, Francisco
2016-07-01
The quality of the quantitative information in single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS) depends directly on the number concentration of the nanoparticles in the sample analyzed, which is proportional to the flux of nanoparticles through the plasma. Particle number concentrations must be selected in accordance with the data acquisition frequency, to control the precision from counting statistics and the bias, which is produced by the occurrence of multiple-particle events recorded as single-particle events. With quadrupole mass spectrometers, the frequency of data acquisition is directly controlled by the dwell time. The effect of dwell times from milli- to microseconds (10 ms, 5 ms, 100 μs, and 50 μs) on the quality of the quantitative data has been studied. Working with dwell times in the millisecond range, precision figures about 5 % were achieved, whereas using microsecond dwell times, the suitable fluxes of nanoparticles are higher and precision was reduced down to 1 %; this was independent of the dwell time selected. Moreover, due to the lower occurrence of multiple-nanoparticle events, linear ranges are wider when dwell times equal to or shorter than 100 μs are used. A calculation tool is provided to determine the optimal concentration for any instrument or experimental conditions selected. On the other hand, the use of dwell times in the microsecond range reduces significantly the contribution of the background and/or the presence of dissolved species, in comparison with the use of millisecond dwell times. Although the use of dwell times equal to or shorter than 100 μs offers improved performance working in single-particle mode, the use of conventional dwell times (3-10 ms) should not be discarded, once their limitations are known.
Cooperative action of KIF1A Brownian motors with finite dwell time
Oriola, David; Casademunt, Jaume
2014-03-01
We study in detail the cooperative action of small groups of KIF1A motors in its monomeric (single-headed) form within an arrangement relevant to vesicle traffic or membrane tube extraction. It has been recently shown that under these circumstances, the presence of a finite dwell time in the motor cycle contributes to remarkably enhance collective force generation [D. Oriola and J. Casademunt, Phys. Rev. Lett. 111, 048103 (2013), 10.1103/PhysRevLett.111.048103]. We analyze this mechanism in detail by means of a two-state noise-driven ratchet model with hard-core repulsive interactions. We obtain staircase-shaped velocity-force curves and show that motors self-organize in clusters with a nontrivial force distribution that conveys a large part of the load to the central motors. Under heavy loads, large clusters adopt a synchronic mode of totally asymmetric steps. We also find a dramatic increase of the collective efficiency with the number of motors. Finally, we complete the study by addressing different interactions that impose spatial constraints such as rigid coupling and raft-induced confinement. Our results reinforce the hypothesis that the specificity of KIF1A to axonal vesicular transport may be deeply related to its high cooperativity.
Directory of Open Access Journals (Sweden)
Dimos Baltas
2010-10-01
Full Text Available Purpose: One of the issues that a planner is often facing in HDR brachytherapy is the selective existence of high dose volumes around some few dominating dwell positions. If there is no information available about its necessity (e.g. location of a GTV, then it is reasonable to investigate whether this can be avoided. This effect can be eliminated by limiting the free modulation of the dwell times. HIPO, an inverse treatment plan optimization algorithm, offers this option.In treatment plan optimization there are various methods that try to regularize the variation of dose non-uniformity using purely dosimetric measures. However, although these methods can help in finding a good dose distribution they do not provide any information regarding the expected treatment outcome as described by radiobiology based indices.Material and methods: The quality of 12 clinical HDR brachytherapy implants for prostate utilizing HIPO and modulation restriction (MR has been compared to alternative plans with HIPO and free modulation (without MR.All common dose-volume indices for the prostate and the organs at risk have been considered together with radiobiological measures. The clinical effectiveness of the different dose distributions was investigated by calculating the response probabilities of the tumors and organs-at-risk (OARs involved in these prostate cancer cases. The radiobiological models used are the Poisson and the relative seriality models. Furthermore, the complication-free tumor control probability, P+ and the biologically effective uniform dose (D = were used for treatment plan evaluation and comparison.Results: Our results demonstrate that HIPO with a modulation restriction value of 0.1-0.2 delivers high quality plans which are practically equivalent to those achieved with free modulation regarding the clinically used dosimetric indices.In the comparison, many of the dosimetric and radiobiological indices showed significantly different results. The
Avelar, Ariane Ferreira Machado; Peterlini, Maria Angélica Sorgini; da Pedreira, Mavilde Luz Gonçalves
2013-06-01
Randomized controlled trial which aimed to verify whether the use of vascular ultrasound (VUS) increases assertiveness in the use of peripheral venous catheter in children, and the catheter dwell time, when compared to traditional puncture. Data were collected after approval of theethical merit. Children and adolescents undergoing VUS-guided peripheral intravenous (GVUS) or puncture guided by clinical assessment of the venous conditions(CG) were included in the study. Significance level was set at pAssertiveness was found in 73 (71.6%) GVUS catheters and in 84(71.8%) of the CG (p=0.970), and catheter dwell time presented a median of less than one day in both groups (p=0.121), showing nostatistically significant difference. VUS did not significantly influence the results of the dependent variables investigated. ClinicalTrials.govNCT00930254.
Long, Lijun; Zhao, Jun
2015-07-01
This paper investigates the problem of adaptive neural tracking control via output-feedback for a class of switched uncertain nonlinear systems without the measurements of the system states. The unknown control signals are approximated directly by neural networks. A novel adaptive neural control technique for the problem studied is set up by exploiting the average dwell time method and backstepping. A switched filter and different update laws are designed to reduce the conservativeness caused by adoption of a common observer and a common update law for all subsystems. The proposed controllers of subsystems guarantee that all closed-loop signals remain bounded under a class of switching signals with average dwell time, while the output tracking error converges to a small neighborhood of the origin. As an application of the proposed design method, adaptive output feedback neural tracking controllers for a mass-spring-damper system are constructed.
Directory of Open Access Journals (Sweden)
Patrício Adriano da Rocha
Full Text Available Many forest-dwelling bats are purported to be widespread in South America, although records are scant from the vast diagonal belt of dry ecosystems that straddles the continent, implying possible sampling deficiencies. Here, we investigate this possibility in the case of four species of bat (Centronycteris maximiliani, Lampronycteris brachyotis, Peropteryx kappleri and Trinycteris nicefori, evaluating whether their disjunct present-day distributions reflect their true zoogeographic characteristics or the subsampling of intermediate zones. We use environmental niche modelling (ENM in an ensemble approach, combining four different modeling techniques, and using niche descriptors based on climatic and remote sensing data, to estimate the potential distribution of the four species. The models indicate that all four species have disjunct distributions in the Amazon and Atlantic forest biomes. The one possible exception is P. kappleri, which the models indicated might potentially occur in humid forest enclaves in western Brazil and eastern Bolivia. The present-day distribution of the species may date back to the Plio-Pleistocene, when the forested biomes of South America were more extensive and connected. Further studies of different chiropteran lineages may provide additional insights into the historic processes of faunal interchange between the Amazon and Atlantic forest biomes.
The Simultaneous Vehicle Scheduling and Passenger Service Problem with Flexible Dwell Times
DEFF Research Database (Denmark)
Fonseca, Joao Filipe Paiva; Larsen, Allan; van der Hurk, Evelien;
times at important transfer points based on expected passenger ows. We introduce a compact mixed integer linear formulation of the SVSPSP-FDT able to address small instances. We also present a meta-heuristic approach to solve medium/large instances of the problem. The e ectiveness of the proposed......In this talk, we deal with a generalization of the well-known Vehicle Scheduling Problem(VSP) that we call Simultaneous Vehicle Scheduling and Passenger Service Problem with Flexible Dwell Times (SVSPSP-FDT). The SVSPSP-FDT generalizes the VSP because the original timetables of the trips can...
Fission yeast mtr1p regulates interphase microtubule cortical dwell-time
Directory of Open Access Journals (Sweden)
Frédérique Carlier-Grynkorn
2014-06-01
Full Text Available The microtubule cytoskeleton plays important roles in cell polarity, motility and division. Microtubules inherently undergo dynamic instability, stochastically switching between phases of growth and shrinkage. In cells, some microtubule-associated proteins (MAPs and molecular motors can further modulate microtubule dynamics. We present here the fission yeast mtr1+, a new regulator of microtubule dynamics that appears to be not a MAP or a motor. mtr1-deletion (mtr1Δ primarily results in longer microtubule dwell-time at the cell tip cortex, suggesting that mtr1p acts directly or indirectly as a destabilizer of microtubules. mtr1p is antagonistic to mal3p, the ortholog of mammalian EB1, which stabilizes microtubules. mal3Δ results in short microtubules, but can be partially rescued by mtr1Δ, as the double mutant mal3Δ mtr1Δ exhibits longer microtubules than mal3Δ single mutant. By sequence homology, mtr1p is predicted to be a component of the ribosomal quality control complex. Intriguingly, deletion of a predicted ribosomal gene, rps1801, also resulted in longer microtubule dwell-time similar to mtr1Δ. The double-mutant mal3Δ rps1801Δ also exhibits longer microtubules than mal3Δ single mutant alone. Our study suggests a possible involvement of mtr1p and the ribosome complex in modulating microtubule dynamics.
Robust linear equation dwell time model compatible with large scale discrete surface error matrix.
Dong, Zhichao; Cheng, Haobo; Tam, Hon-Yuen
2015-04-01
The linear equation dwell time model can translate the 2D convolution process of material removal during subaperture polishing into a more intuitional expression, and may provide relatively fast and reliable results. However, the accurate solution of this ill-posed equation is not so easy, and its practicability for a large scale surface error matrix is still limited. This study first solves this ill-posed equation by Tikhonov regularization and the least square QR decomposition (LSQR) method, and automatically determines an optional interval and a typical value for the damped factor of regularization, which are dependent on the peak removal rate of tool influence functions. Then, a constrained LSQR method is presented to increase the robustness of the damped factor, which can provide more consistent dwell time maps than traditional LSQR. Finally, a matrix segmentation and stitching method is used to cope with large scale surface error matrices. Using these proposed methods, the linear equation model becomes more reliable and efficient in practical engineering.
Theoretical Delay Time Distributions
Nelemans, Gijs; Bours, Madelon
2012-01-01
We briefly discuss the method of population synthesis to calculate theoretical delay time distributions of type Ia supernova progenitors. We also compare the results of the different research groups and conclude that although one of the main differences in the results for single degenerate progenitors is the retention efficiency with which accreted hydrogen is added to the white dwarf core, this cannot explain all the differences.
Theoretical Delay Time Distributions
Nelemans, Gijs; Toonen, Silvia; Bours, Madelon
2013-01-01
We briefly discuss the method of population synthesis to calculate theoretical delay time distributions of Type Ia supernova progenitors. We also compare the results of different research groups and conclude that, although one of the main differences in the results for single degenerate progenitors is the retention efficiency with which accreted hydrogen is added to the white dwarf core, this alone cannot explain all the differences.
Directory of Open Access Journals (Sweden)
Naoyuki Matsumoto
2015-07-01
Full Text Available One aspect of carbon nanotube (CNT synthesis that remains an obstacle to realize industrial mass production is the growth efficiency. Many approaches have been reported to improve the efficiency, either by lengthening the catalyst lifetime or by increasing the growth rate. We investigated the applicability of dwell time and carbon flux control to optimize yield, growth rate, and catalyst lifetime of water-assisted chemical vapor deposition of single-walled carbon nanotube (SWCNT forests using acetylene as a carbon feedstock. Our results show that although acetylene is a precursor to CNT synthesis and possesses a high reactivity, the SWCNT forest growth efficiency is highly sensitive to dwell time and carbon flux similar to ethylene. Through a systematic study spanning a wide range of dwell time and carbon flux levels, the relationship of the height, growth rate, and catalyst lifetime is found. Further, for the optimum conditions for 10 min growth, SWCNT forests with ~2500 μm height, ~350 μm/min initial growth rates and extended lifetimes could be achieved by increasing the dwell time to ~5 s, demonstrating the generality of dwell time control to highly reactive gases.
Matsumoto, Naoyuki; Oshima, Azusa; Sakurai, Shunsuke; Yamada, Takeo; Yumura, Motoo; Hata, Kenji; Futaba, Don N.
2015-01-01
One aspect of carbon nanotube (CNT) synthesis that remains an obstacle to realize industrial mass production is the growth efficiency. Many approaches have been reported to improve the efficiency, either by lengthening the catalyst lifetime or by increasing the growth rate. We investigated the applicability of dwell time and carbon flux control to optimize yield, growth rate, and catalyst lifetime of water-assisted chemical vapor deposition of single-walled carbon nanotube (SWCNT) forests using acetylene as a carbon feedstock. Our results show that although acetylene is a precursor to CNT synthesis and possesses a high reactivity, the SWCNT forest growth efficiency is highly sensitive to dwell time and carbon flux similar to ethylene. Through a systematic study spanning a wide range of dwell time and carbon flux levels, the relationship of the height, growth rate, and catalyst lifetime is found. Further, for the optimum conditions for 10 min growth, SWCNT forests with ~2500 μm height, ~350 μm/min initial growth rates and extended lifetimes could be achieved by increasing the dwell time to ~5 s, demonstrating the generality of dwell time control to highly reactive gases.
Signature of the N=126 shell closure in dwell times of alpha-particle tunneling
Kelkar, N G
2016-01-01
Characteristic quantities such as the penetration and preformation probabilities, assault frequency and tunneling times in the tunneling description of alpha decay of heavy nuclei are explored to reveal their sensitivity to neutron numbers in the vicinity of the magic neutron number $N$ = 126. Using realistic nuclear potentials, the sensitivity of these quantities to the parameters of the theoretical approach is also tested. An investigation of the region from $N=116$ to $N=132$ in Po nuclei reveals that the tunneling $\\alpha$ particle spends the least amount of time with an $N=126$ magic daughter nucleus. The shell closure at $N=126$ seems to affect the behaviour of the dwell times of the tunneling alpha particles and this occurs through the influence of the $Q$-values involved.
Signature of the N = 126 shell closure in dwell times of alpha-particle tunneling
Kelkar, N. G.; Nowakowski, M.
2016-10-01
Characteristic quantities such as the penetration and preformation probabilities, assault frequency and tunneling times in the tunneling description of alpha decay of heavy nuclei are explored to reveal their sensitivity to neutron numbers in the vicinity of the magic neutron number N = 126. Using realistic nuclear potentials, the sensitivity of these quantities to the parameters of the theoretical approach is also tested. An investigation of the region from N = 116 to N = 132 in Po nuclei reveals that the tunneling α particle spends the least amount of time with an N = 126 magic daughter nucleus. The shell closure at N = 126 seems to affect the behavior of the dwell times of the tunneling alpha particles and this occurs through the influence of the Q-values involved.
Asynchronous H∞ filtering for linear switched systems with average dwell time
Wang, Bo; Zhang, Hongbin; Wang, Gang; Dang, Chuangyin
2016-09-01
This paper is concerned with the H∞ filtering problem for a class of continuous-time linear switched systems with the asynchronous behaviours, where 'asynchronous' means that the switching of the filters to be designed has a lag to the switching of the system modes. By using the Lyapunov-like functions and the average dwell time technique, a sufficient condition is obtained to guarantee the asymptotic stability with a weighted H∞ performance index for the filtering error system. Moreover, the results are formulated in the form of linear matrix inequalities that are numerical feasible. As a result, the filter design problem is solved. Finally, an illustrative numerical example is presented to show the effectiveness of the results.
2015-01-01
Purpose In high-dose-rate (HDR) brachytherapy (BT), the source dwell times and dwell positions are essential treatment planning parameters. An optimal choice of these factors is fundamental to obtain the desired target coverage with the lowest achievable dose to the organs at risk (OARs). This study evaluates relevant dose parameters in cervix brachytherapy in order to assess existing tandem-ring dwell time ratio used at the first HDR BT center in Nigeria, and compare it with an alternative s...
The Scaling of the RMS with Dwell Time in NANOGrav Pulsars
Handzo, Emma; Lommen, Andrea N; Perrodin, Delphine
2015-01-01
Pulsar Timing Arrays (PTAs) are collections of well-timed millisecond pulsars that are being used as detectors of gravitational waves (GWs). Given current sensitivity, projected improvements in PTAs and the predicted strength of the GW signals, the detection of GWs with PTAs could occur within the next decade. One way we can improve a PTA is to reduce the measurement noise present in the pulsar timing residuals. If the pulsars included in the array display uncorrelated noise, the root mean square (RMS) of the timing residuals is predicted to scale as $\\mathrm{T}^{-1/2}$, where T is the dwell time per observation. In this case, the sensitivity of the array can be increased by increasing T. We studied the 17 pulsars in the five year North American Nanohertz Observatory for Gravitational Waves (NANOGrav) data set to determine if the noise in the timing residuals of the pulsars observed was consistent with this property. For comparison, we performed the same analysis on PSR B1937+21, a pulsar that is known to dis...
Influence of the bulk diffusion of rubidium and sodium atoms in glass on their surface dwell time
Atutov, S. N.; Benimetskii, F. A.; Makarov, A. O.
2017-05-01
This paper presents the results of measurement of the surface potential and the dwell time of Rb and Na atoms on the surface of S-52 molybdenum glass. It is found that at temperatures below the glass transition temperature, the temperature dependence of the dwell time of Rb atoms is well described by the Arrhenius formula. The surface potentials for Rb and Na are measured to be 0.67 and 1.37 eV, respectively. At temperatures above the glass transition temperature, the dwell time of these atoms increases abnormally. The reason for this is that during impact of an atom on the surface of molten glass, it can penetrate into the volume of the window and then return by diffusion and desorb from the surface. In this case, the dwell time of the atom on the glass is determined by the diffusion time and can be very significant, despite the relatively low potential barrier at the surface and high temperature.
Desai, Kush R; Laws, James L; Salem, Riad; Mouli, Samdeep K; Errea, Martin F; Karp, Jennifer K; Yang, Yihe; Ryu, Robert K; Lewandowski, Robert J
2017-06-01
Despite growth in placement of retrievable inferior vena cava filters, retrieval rates remain low. Filters with extended implantation times present a challenge to retrieval, where standard techniques often fail. The development of advanced retrieval techniques has positively impacted retrieval of retrievable inferior vena cava filters with prolonged dwell times; however, there is no precise definition of the time point when advanced techniques become necessary. We aim to define prolonged retrievable inferior vena cava filters dwell time by determining the inflection point when the risk of standard retrieval technique failure increases significantly, necessitating advanced retrieval techniques to maintain overall technical success of retrieval. From January 2009 to April 2015, 762 retrieval procedures were identified from a prospectively acquired database. We assessed patient age/sex, filter dwell time, procedural technical success, the use of advanced techniques, and procedure-related adverse events. Overall retrieval success rate was 98% (n=745). When standard retrieval techniques failed, advanced techniques were used; this was necessary 18% of the time (n=138). Logistic regression identified that dwell time was the only risk factor for failure of standard retrieval technique (odds ratio, 1.08; 95% confidence interval, 1.05-1.10; Ptechnique failure was 40.9%. Adverse events occurred at a rate of 2% (n=18; 15 minor and 3 major). The necessity of advanced techniques to maintain technical success of retrieval increases with dwell time. Patients with retrievable inferior vena cava filters in place beyond 7 months may benefit from referral to centers with expertise in advanced filter retrieval. © 2017 American Heart Association, Inc.
Effect of Dwell Time on the Mental Health of U.S. Military Personnel with Multiple Combat Tours
2012-01-01
government studies of health effects of the Gulf War. Am J Epidemiol. 1998;148(4):315---323. 18. Lazarus RS, Folkman S . Stress , appraisal, and coping ...the theory behind the stress ---exhaustion model is based on stressor duration, lack of an adequate dwell time may prevent the service member from...second deployment.8 Other studies have also identified increases in mental health symp- toms, particularly symptoms of posttraumatic stress disorder
2014-04-01
on mental health outcomes and should be exam- ined to identify key determinants of resilience. The issues of a dwell-titTie policy and whether certain...Gahm GA, Swanson RD, Duma SJ; Association between number of deployments to Iraq and niental health screening outcomes in US Army soldiers. J Clin
Distribution of tsunami interevent times
Geist, E.L.; Parsons, T.
2008-01-01
The distribution of tsunami interevent times is analyzed using global and site-specific (Hilo, Hawaii) tsunami catalogs. An empirical probability density distribution is determined by binning the observed interevent times during a period in which the observation rate is approximately constant. The empirical distributions for both catalogs exhibit non-Poissonian behavior in which there is an abundance of short interevent times compared to an exponential distribution. Two types of statistical distributions are used to model this clustering behavior: (1) long-term clustering described by a universal scaling law, and (2) Omori law decay of aftershocks and triggered sources. The empirical and theoretical distributions all imply an increased hazard rate after a tsunami, followed by a gradual decrease with time approaching a constant hazard rate. Examination of tsunami sources suggests that many of the short interevent times are caused by triggered earthquakes, though the triggered events are not necessarily on the same fault.
Energy Technology Data Exchange (ETDEWEB)
Sanquist, Thomas F.; Greitzer, Frank L.; Slavich, Antoinette L.; Littlefield, Rik J.; Littlefield, Janis S.; Cowley, Paula J.
2004-09-28
Technology-based enhancement of information analysis requires a detailed understanding of the cognitive tasks involved in the process. The information search and report production tasks of the information analysis process were investigated through evaluation of time-stamped workstation data gathered with custom software. Model tasks simulated the search and production activities, and a sample of actual analyst data were also evaluated. Task event durations were calculated on the basis of millisecond-level time stamps, and distributions were plotted for analysis. The data indicate that task event time shows a cyclic pattern of variation, with shorter event durations (< 2 sec) reflecting information search and filtering, and longer event durations (> 10 sec) reflecting information evaluation. Application of cognitive principles to the interpretation of task event time data provides a basis for developing “cognitive signatures” of complex activities, and can facilitate the development of technology aids for information intensive tasks.
Dettmers, Robert; Brekelmans, Wouter; Leijnen, Michiel; van der Burg, Boudewijn; Ritchie, Ewan
2016-09-01
Infection following orthopedic implants for bone fixation or joint replacement is always serious and may require removal of the osteosynthetic material. Negative pressure wound therapy with instillation and dwell time (NPWTi-d) is an emerging therapy for the treatment of complex wounds, including infected wounds with osteosynthetic material. The purpose of this case study was to evaluate the outcomes of 4 patients (1 man, 3 women; age range 49 to 71 years) with a postoperative wound infection (POWI) following fracture repair and internal fixation. All patients were at high risk for surgical complications, including infections. Standard infection treatments (antibiotics) had been unsuccessful. Based on the available literature, a NPWTi-d protocol was developed. Following surgical debridement, wounds were instilled with polyhexanide biguanide with a set dwell time of 15 minutes, followed by continuous NPWTi-d of -125 mm Hg for 4 hours. The system was changed every 3 to 4 days until sufficient granulation tissue was evident and negative pressure without instillation could be used. Systemic antibiotics were continued in all patients. Granulation tissue was found to be sufficient in 12 to 35 days in the 4 cases, no recurrence of infection was noted, and the osteosynthesis material remained in place. No adverse events were observed. Research is needed to compare the safety and effectiveness of this adjunct treatment in the management of challenging wounds to other patient and wound management approaches.
Jing, Yindi
2014-01-01
Distributed Space-Time Coding (DSTC) is a cooperative relaying scheme that enables high reliability in wireless networks. This brief presents the basic concept of DSTC, its achievable performance, generalizations, code design, and differential use. Recent results on training design and channel estimation for DSTC and the performance of training-based DSTC are also discussed.
Indoor radon measurements in Turkey dwellings.
Celebi, N; Ataksor, B; Taskın, H; Bingoldag, N Albayrak
2015-12-01
In this work, indoor radon radioactivity concentration levels have been measured in dwellings of Turkey within the frame of the National Radon Monitoring Programme. The (222)Rn concentrations were measured with time-integrating passive nuclear etched track detectors in 7293 dwellings in 153 residential units of 81 provinces, and the radon map of Turkey was prepared. Indoor radon concentrations were distributed in the range of 1-1400 Bq m(-3). The arithmetic mean of the radon gas concentration was found to be 81 Bq m(-3); the geometric mean was 57 Bq m(-3) with a geometric standard deviation of 2.3.
Bloch, Mette L; Jønsson, Line R; Kristensen, Morten T
Originally, the Timed Up & Go (TUG) test was described as including a practice trial before a timed trial, but recent studies in individuals with hip fracture have reported that performance improved with a third trial and that high intertester reliability was achieved when the fastest of 3 timed trials was used. Thus, the fastest of 3 TUG trials is recommended when testing individuals with hip fracture. To our knowledge, no study has examined the number of trials needed to achieve performance stability on the TUG test (defined as no further improvement on subsequent trials) when performed by older individuals without hip fracture. The aim of the study, therefore, was to examine whether a third TUG trial is faster than either of 2 TUG trials conducted according to standardized TUG instructions and whether the fastest of 3 trials is the most appropriate measure to apply in hospitalized and community-dwelling older individuals. Eighty-two participants (50 from a geriatric hospital unit and 32 from an outpatient geriatric center; 52 women, 30 men) with a mean (SD) age of 83.6 (7.9) years were included in this cross-sectional study. All participants (except one from the hospital unit) performed 3 TUG trials, as fast as safely possible on the same day, and separated by up to 1-minute pauses. A rollator (4-wheeled rolling walker) was used as a standardized walking aid in the geriatric hospital unit, whereas participants used their normal walking aid (if any) in the outpatient geriatric center. The fastest trial was trial 3 for 47 (57%), trial 2 for 25 (31%), and trial 1 for 10 (12%). Repeated-measures analyses of variance with Bonferroni corrections showed that TUG times improved from trial 1 to trial 3 (P timed trials was significantly (P < .001) faster than the other 2 trials. We suggest that the fastest of the 3 TUG trials is recorded instead of the second trial in both hospitalized and community-dwelling older individuals.
Directory of Open Access Journals (Sweden)
Fei Lin
2016-03-01
Full Text Available With its large capacity, the total urban rail transit energy consumption is very high; thus, energy saving operations are quite meaningful. The effective use of regenerative braking energy is the mainstream method for improving the efficiency of energy saving. This paper examines the optimization of train dwell time and builds a multiple train operation model for energy conservation of a power supply system. By changing the dwell time, the braking energy can be absorbed and utilized by other traction trains as efficiently as possible. The application of genetic algorithms is proposed for the optimization, based on the current schedule. Next, to validate the correctness and effectiveness of the optimization, a real case is studied. Actual data from the Beijing subway Yizhuang Line are employed to perform the simulation, and the results indicate that the optimization method of the dwell time is effective.
Distributed synthesis in continuous time
DEFF Research Database (Denmark)
Hermanns, Holger; Krčál, Jan; Vester, Steen
2016-01-01
. Indeed, the explicit continuous time enables players to communicate their states by delaying synchronisation (which is unrestricted for non-urgent models). In general, the problems are undecidable already for two players in the quantitative case and three players in the qualitative case. The qualitative......We introduce a formalism modelling communication of distributed agents strictly in continuous-time. Within this framework, we study the problem of synthesising local strategies for individual agents such that a specified set of goal states is reached, or reached with at least a given probability....... The flow of time is modelled explicitly based on continuous-time randomness, with two natural implications: First, the non-determinism stemming from interleaving disappears. Second, when we restrict to a subclass of non-urgent models, the quantitative value problem for two players can be solved in EXPTIME...
Directory of Open Access Journals (Sweden)
Shahan Derkarabetian
Full Text Available BACKGROUND: Many cave-dwelling animal species display similar morphologies (troglomorphism that have evolved convergent within and among lineages under the similar selective pressures imposed by cave habitats. Here we study such ecomorphological evolution in cave-dwelling Sclerobuninae harvestmen (Opiliones from the western United States, providing general insights into morphological homoplasy, rates of morphological change, and the temporal context of cave evolution. METHODOLOGY/PRINCIPAL FINDINGS: We gathered DNA sequence data from three independent gene regions, and combined these data with Bayesian hypothesis testing, morphometrics analysis, study of penis morphology, and relaxed molecular clock analyses. Using multivariate morphometric analysis, we find that phylogenetically unrelated taxa have convergently evolved troglomorphism; alternative phylogenetic hypotheses involving less morphological convergence are not supported by Bayesian hypothesis testing. In one instance, this morphology is found in specimens from a high-elevation stony debris habitat, suggesting that troglomorphism can evolve in non-cave habitats. We discovered a strong positive relationship between troglomorphy index and relative divergence time, making it possible to predict taxon age from morphology. Most of our time estimates for the origin of highly-troglomorphic cave forms predate the Pleistocene. CONCLUSIONS/SIGNIFICANCE: While several regions in the eastern and central United States are well-known hotspots for cave evolution, few modern phylogenetic studies have addressed the evolution of cave-obligate species in the western United States. Our integrative studies reveal the recurrent evolution of troglomorphism in a perhaps unexpected geographic region, at surprisingly deep time depths, and in sometimes surprising habitats. Because some newly discovered troglomorphic populations represent undescribed species, our findings stress the need for further biological
Zhao, Xudong; Yin, Yunfei; Niu, Ben; Zheng, Xiaolong
2016-08-01
In this paper, the problem of switching stabilization for a class of switched nonlinear systems is studied by using average dwell time (ADT) switching, where the subsystems are possibly all unstable. First, a new concept of ADT is given, which is different from the traditional definition of ADT. Based on the new proposed switching signals, a sufficient condition of stabilization for switched nonlinear systems with unstable subsystems is derived. Then, the T-S fuzzy modeling approach is applied to represent the underlying nonlinear system to make the obtained condition easily verified. A novel multiple quadratic Lyapunov function approach is also proposed, by which some conditions are provided in terms of a set of linear matrix inequalities to guarantee the derived T-S fuzzy system to be asymptotically stable. Finally, a numerical example is given to demonstrate the effectiveness of our developed results.
Directory of Open Access Journals (Sweden)
Mijajlović Miroslav M.
2016-01-01
Full Text Available After successful welding, destructive testing into test samples from Al 2024-T351 friction stir butt welds showed that tensile strength of the weld improve along the joint line, while dimensions of the weld nugget decrease. For those welds, both the base material and the welding tool constantly cool down during the welding phase. Obviously, the base material became overheated during the long dwelling phase what made conditions for creation of joints with the reduced mechanical properties. Preserving all process parameters but varying the dwelling time from 5-27 seconds a new set of welding is done to reach maximal achievable tensile strength. An analytical-numerical-experimental model is used for optimising the duration of the dwelling time while searching for the maximal tensile strength of the welds
Timing issues in distributed testing
Institute of Scientific and Technical Information of China (English)
HUANG Chuan-dong; JIANG Fan
2007-01-01
The objective of conformance testing is to determine whether an implementation under test (IUT) conforms to its specification. In distributed test architecture where there are multiple remote testers, the objective can be complicated by the fact that testers may encounter controllability and observability problems during the application of a test sequence. A certain amount of work has been done in the area of generating test sequence that is free from these problems. However, few researchers investigate them from the aspect of test execution. This work studies the test execution phase when test sequences are applied to the implementation and it is pointed out that controllability and observability problems can be resolved if and only if the test system implements some timing constraints. When determining these constraints, the dynamic time information during test is taken into account, which reduces the test execution time and improves test efficiency further.
Dwell time of a Brownian interacting molecule in a cellular microdomain
Taflia, A; Taflia, Adi; Holcman, David
2006-01-01
The time spent by an interacting Brownian molecule inside a bounded microdomain has many applications in cellular biology, because the number of bounds is a quantitative signal, which can initiate a cascade of chemical reactions and thus has physiological consequences. In the present article, we propose to estimate the mean time spent by a Brownian molecule inside a microdomain $\\Omega$ which contains small holes on the boundary and agonist molecules located inside. We found that the mean time depends on several parameters such as the backward binding rate (with the agonist molecules), the mean escape time from the microdomain and the mean time a molecule reaches the binding sites (forward binding rate). In addition, we estimate the mean and the variance of the number of bounds made by a molecule before it exits $\\Omega$. These estimates rely on a boundary layer analysis of a conditional mean first passage time, solution of a singular partial differential equation. In particular, we apply the present results ...
Institute of Scientific and Technical Information of China (English)
QIU JianBin; FENG Gang; YANG Jie
2009-01-01
This paper investigates the problem of robust exponential H_∞ static output feedback controller design for a class of discrete-time switched linear systems with polytopic-type time-varying parametric uncertainties.The objective is to design a switched static output feedback controller guaranteeing the exponential stability of the resulting closed-loop system with a minimized exponential H_∞ performance under average dwell-time switching scheme.Based on a parameter-dependent discontinuous switched Lyapunov function combined with Finsler's lemma and Dualization lemma,some novel conditions for exponential H_∞ performance analysis are first proposed and in turn the static output feedback controller designs are developed.It is shown that the controller gains can be obtained by solving a set of linear matrix inequalities (LMIs),which are numerically efficient with commercially available software.Finally,a simulation example is provided to illustrate the effectiveness of the proposed approaches.
Yao, Hiroshi; Takashima, Yuki; Araki, Yuko; Uchino, Akira; Yuzuriha, Takefumi; Hashimoto, Manabu
2015-11-01
Although physical inactivity is a major public health problem, the causative factors for physical inactivity per se are poorly understood. To address this issue, we investigated the relationship between deep white matter lesions (DWMLs) on magnetic resonance imaging, apathy, and physical activities using structural equation modeling (SEM). We examined 317 community-dwelling elderly subjects (137 men and 180 women with a mean age of 64.5 years) without dementia or clinically apparent depression. Physical activity was assessed with a questionnaire consisting of 3 components (leisure-time, work, and sport activities). The mean score from the apathy scale (a visual analogue version of Starkstein's apathy scale) of the Grades 2-3 DWML group was 420 (95% confidence interval [CI] 379-461), which was lower (more apathetic) than the Grade 0 DWML group score of 478 (95% CI 463-492) after adjustment for education as a covariate. SEM showed that the direct paths from DWMLs or education to apathy were significant, and the direct path from apathy to leisure-time activity was highly significant (β = .25, P depression would have a significant impact on activities of daily living and quality of life. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.
Institute of Scientific and Technical Information of China (English)
XIAO-DONG YU; TIAN-HONG LUO; JIAN YANG; HONG-ZHANG ZHOU
2006-01-01
The influence of edge effect on ground-dwelling beetles (Coleoptera) across a forest-clearcut ecotone was studied in Wolong Natural Reserve, southwestern China. During the field research, a total of 30 739 beetles were collected with pitfall traps along transects, which extending 100 m from the edge into the forest interior and 100 m into the clearcut. Of the collection, Carabidae comprised 92%, Staphylinidae 3%, Curculionidae 2%, and Tenebrionidae 2%, and these four families can be considered as abundant groups. Family richness, Shannon diversity and equitability display a significant decrease from forest interior, edge to clearcut. Based on the family composition and abundance, ground-dwelling beetles of the forest interior can be separated from those in the clearcut by Principal coordinate analysis ordination, and beetle assemblages in the forest edge were more similar to forest assemblages than to those found in the clearcut by cluster analysis. Seasonal dynamics of family richness showed a monotone peak in the middle season, with a highest value in the forest interior and a lowest value in the clearcut. Family abundance showed two peaks in the middle season, always with more individuals in the clearcut than in the forest interior or in the edge. Multiple linear regression analyses showed that the cover of shrub and fitter were the two most important factors in determining family richness, Shannon diversity, equitability and abundance. Our results show that the forest edge and clearcut have obviously different composition and diversity of ground-dwelling beetles from forest interior at the family level. However, more edges have been formed due to increasing forest fragmentation (clearcutting or logging), so it is necessary to preserve large and intact forest to protect the diversity of ground-dwelling beetles in Wolong Natural Reserve.
Akonur, Alp; Guest, Steven; Sloand, James A.; Leypoldt, John K.
2013-01-01
♦ Background: Remaining edema-free is a challenge for many automated peritoneal dialysis (APD) patients, especially those with fast (“high”) transport characteristics. Although increased use of peritoneal dialysis (PD) solutions with high glucose concentrations may improve volume control, frequent use of such solutions is undesirable. ♦ Methods: We used the 3-pore kinetic model to evaluate 4 alternative therapy prescriptions for the APD day exchange in anuric patients with high, high-average, and low-average transport characteristics. Four prescriptions were modeled: Therapy 1: Optimal, individualized dwell times with a dry periodTherapy 2: Use of a midday exchangeTherapy 3: Use of an icodextrin-containing dialysate during a 14-hour dwellTherapy 4: Use of optimal, individualized dwell times, followed by an icodextrin dwell to complete the daytime period The alternative therapies were compared with a reference standard therapy using glucose solution during a 14-hour dwell. The nighttime prescription was identical in all cases (10 L over 10 hours), and all glucose solutions contained 2.27% glucose. Net ultrafiltration (UF), sodium removal (NaR), total carbohydrate (CHO) absorption, and weekly urea Kt/V for a 24-hour period were computed and compared. ♦ Results: The UF and NaR were substantially higher with therapy 1 than with standard therapy (1034 mL vs 621 mL and 96 mmol vs 51 mmol respectively), without significant changes in CHO absorption or urea Kt/V. However, therapy 1 resulted in reduced β2-microglobulin clearance (0.74 mL/min vs 0.89 mL/min with standard therapy). Compared with therapy 1, therapy 2 improved UF and NaR (1062 mL vs 1034 mL and 99 mmol vs 96 mmol); however, that improvement is likely not clinically significant. Therapy 2 also resulted in a higher Kt/V (2.07 vs 1.72), but at the expense of higher glucose absorption (difference: 42 g). The UF and NaR were highest with a long icodextrin-containing daytime dwell either preceded by a
Practicing the attentional Dwell Away?
DEFF Research Database (Denmark)
Petersen, Anders; Kyllingsbæk, Søren; Bundesen, Claus Mogens
2007-01-01
. The results suggest that the majority of subjects may learn to optimize their performance reducing the attentional dwell time effect substantially. Further, the reduction in the attentional dwell time effect seems to be closely linked to the ability of the subject to inhibit eye movements while performing......Studies of the time course of visual attention have identified a temporary functional blindness to the second of two spatially separated targets: attending to one visual stimulus may lead to impairments in identifying a second stimulus presented about 200-500 ms later than the first. The phenomenon...... is known as the attentional dwell time (e.g. Duncan, Ward, Shapiro, 1994). Previous studies of attentional dwell time have all used naive subjects running few (
Borges in my office: the analysis of a man dwelling outside of time.
Shoshani, Michael; Shoshani, Batya
2013-07-01
This article weaves together two threads: the intricacies of the analysis of a difficult-to-reach yet extraordinary patient and the literary works of Jorge Luis Borges, which played a significant role in the analysis as a source of inspiration, enriching the analyst's reverie and opening up new psychic spaces. The authors demonstrate the analyst's recourse to several of Borges's stories in order to enrich his own inner world and to better understand the analysand. Some of these stories are briefly presented through the analyst's dialogue with them, and there is a discussion of their function in facilitating the process of working through issues of time, memory, mortality, and identity, contributing to the enhancement of the patient's ability to come face to face with the unwanted, split-off parts of his self and of reality. © 2013 The Psychoanalytic Quarterly, Inc.
Research in Distributed Real-Time Systems
Mukkamala, R.
1997-01-01
This document summarizes the progress we have made on our study of issues concerning the schedulability of real-time systems. Our study has produced several results in the scalability issues of distributed real-time systems. In particular, we have used our techniques to resolve schedulability issues in distributed systems with end-to-end requirements. During the next year (1997-98), we propose to extend the current work to address the modeling and workload characterization issues in distributed real-time systems. In particular, we propose to investigate the effect of different workload models and component models on the design and the subsequent performance of distributed real-time systems.
Timing and time signal distribution in digital communications networks
Kihara, Masami; Imaoka, Atushi
1992-06-01
The timing signal distribution characteristics of a digital communications network are evaluated to determine the Maximum Time Interval Error (MTIE) of the network; reference is made to the performance of network components such as transmission systems, slave clocks and timing distribution systems in intraoffices. The MTIE of each component is measured and used to determine the allowable MTIE of that component. The maximum number of slave node chains is shown to be 20. Time signal distribution performance is detailed. It is shown that time synchronization accuracy is of the order of submicroseconds between nodes separated by 2400 km over a two year period. For intra-office time signal distribution, the relative time accuracy is less than 3 nanoseconds using an 8 Mb/s round trip digital interface to connect a time signal supply in an office to dispersed equipment.
Energy Technology Data Exchange (ETDEWEB)
Hamilton, R [Univ Arizona, Tucson, AZ (United States); Patel, P; Balaggan, K; Restori, M; Ilginis, T [Moorfields Eye Hospital, London (United Kingdom); Drew, M; McGovern, M; Vitali, J; Marsteller, L [Salutaris Medical Devices, Inc., Tucson, AZ (United States)
2015-06-15
Purpose: To evaluate the variations in dwell times and doses expected when using an episcleral brachytherapy device for treatment of neovascular agerelated macular degeneration (n-AMD) based on accurate imaging modalities Methods: Data from 40 eyes from 40 subjects with known n- AMD acquired through the Distance of Choroid Study (DOCS) conducted at Moorfields Eye Hospital was used to determine the target depth; the distance from the outer scleral surface of the eye, through the choroid, to the apex of the choroidal neovascularization (CNV). Each subject underwent, in triplicate, enhanced-depth Spectral Domain Optical Coherence Tomography (SD-OCT), Swept Source Optical Coherence Tomography, (SS-OCT) and Ocular Ultrasound (O-US). These data are the most comprehensive and accurate measurements of the dimensions of the CNV and adjacent layers of the eye for this cohort of patients. During treatment of n-AMD, patients receive a dose of 24Gy to the apex at the target depth. Using the percentage depth dose for a Sr-90 episcleral brachytherapy device, dwell times and doses to the apex were computed to determine the expected variations. Results: The mean target depth and the 95% confidence interval (CI) determined by combining O-US with SD-OCT were 1326 (956,1696)µm and with SS-OCT were 1332 (970,1693)µm. The calculated corresponding mean dwell times and 95% (CI) were 334 (223,445)s and 335 (226,445)s for SD-OCT and SS-OCT determined depths, respectively. The corresponding mean apex dose and 95% (CI) were 24 (35.9,18.0)Gy (SD-OCT) and 24 (35.6,18.1)Gy (SS-OCT). Conclusion: For episcleral brachytherapy treatment of n-AMD, using a patient population average target depth for treatment planning is inadequate, resulting in dose variations of a factor of approximately two over the 95% CI and larger variations for a nontrivial segment of the population. Each patient should have individualized imaging studies to determine the target depth for use in the dwell time calculation
Energy Distribution in LTB Space-time
Salti, M; Salti, Mustafa; Havare, Ali
2005-01-01
Using general relativity analogs of Bergmann-Thomson, Papapetrou, Landau-Lifshitz and Einstein energy and momentum definitions, we find the energy distribution (due to matter plus fields) in the LTB Space-time. The energy distribution is found well defined and the same in all of these energy-momentum complexes.
Distributed Algorithms for Time Optimal Reachability Analysis
DEFF Research Database (Denmark)
Zhang, Zhengkui; Nielsen, Brian; Larsen, Kim Guldstrand
2016-01-01
Time optimal reachability analysis is a novel model based technique for solving scheduling and planning problems. After modeling them as reachability problems using timed automata, a real-time model checker can compute the fastest trace to the goal states which constitutes a time optimal schedule....... We propose distributed computing to accelerate time optimal reachability analysis. We develop five distributed state exploration algorithms, implement them in \\uppaal enabling it to exploit the compute resources of a dedicated model-checking cluster. We experimentally evaluate the implemented...... algorithms with four models in terms of their ability to compute near- or proven-optimal solutions, their scalability, time and memory consumption and communication overhead. Our results show that distributed algorithms work much faster than sequential algorithms and have good speedup in general....
Distributed Algorithms for Time Optimal Reachability Analysis
DEFF Research Database (Denmark)
Zhang, Zhengkui; Nielsen, Brian; Larsen, Kim Guldstrand
2016-01-01
. We propose distributed computing to accelerate time optimal reachability analysis. We develop five distributed state exploration algorithms, implement them in \\uppaal enabling it to exploit the compute resources of a dedicated model-checking cluster. We experimentally evaluate the implemented...... algorithms with four models in terms of their ability to compute near- or proven-optimal solutions, their scalability, time and memory consumption and communication overhead. Our results show that distributed algorithms work much faster than sequential algorithms and have good speedup in general....
Kose, Yujiro; Ikenaga, Masahiro; Yamada, Yosuke; Morimura, Kazuhiro; Takeda, Noriko; Ouma, Shinji; Tsuboi, Yoshio; Yamada, Tatsuo; Kimura, Misaka; Kiyonaga, Akira; Higaki, Yasuki; Tanaka, Hiroaki
2016-12-01
This study aimed to ascertain if performance on the Timed Up and Go (TUG) test is associated with indicators of brain volume and cognitive functions among community-dwelling older adults with normal cognition or mild cognitive impairment. Participants were 80 community-dwelling older adults aged 65-89years (44 men, 36 women), including 20 with mild cognitive impairment. Participants completed the TUG and a battery of cognitive assessments, including the Mini-Mental State Examination (MMSE), the Logical Memory I and II (LM-I, LM-II) subtests of the Wechsler Memory Scale-Revised; and the Trail Making Test A and B (TMT-A, TMT-B). Bilateral, right- and left-side medial temporal area atrophy as well as whole gray and white matter indices were determined with the Voxel-based Specific Regional Analysis System for Alzheimer's Disease. We divided participants into three groups based on TUG performance: "better" (≤6.9s); "normal" (7-10s); and "poor" (≥10.1s). Worse TMT-A and TMT-B performance showed significant independent associations with worse TUG performance (P<0.05, P<0.01 for trend, respectively). After adjusting for covariates, severe atrophy of bilateral, right-, and left-side medial temporal areas were significantly independently associated with worse TUG performance (P<0.05 for trend). However, no significant associations were found between MMSE, LM-I, LM-II, whole gray and white matter indices, and TUG performance. Worse TUG performance is related to poor performance on TMT-A and TMT-B, and is independently associated with severe medial temporal area atrophy in community-dwelling older adults. Copyright © 2016 Elsevier Inc. All rights reserved.
Singh, Abhishek; De Bisschop, Cathérine; Schut, Henk; Van Humbeeck, Jan; Van Den Mooter, Guy
2015-10-01
Compression of miconazole-poly (1-vinylpyrrolidone-co-vinyl acetate) (PVPVA64) solid dispersions prepared by spray drying and hot-melt extrusion was performed to gain insights into effect of compression pressure, dwell time, and preparation method on compression-dependent phase behavior. The solid dispersions prepared by spray drying were initially phase-separated showing two glass transition temperature (Tg), whereas the extruded samples showed one single Tg indicating better mixing. Compression caused mixing of spray-dried solid dispersions at high compression pressures and especially high dwell times. The extruded systems showed no statistically significant differences. However, physical mixtures made up from extruded samples containing 20% and 40% of active pharmaceutical ingredient underwent mixing upon compression. Coincidence Doppler measurements were performed to quantify the free volume of PVPVA64 which is a major contributor to the free volume in the solid dispersion matrix. A small but significant difference was found between the open free volume of the pure polymer subjected to varied manufacturing processes. Compression-induced plastic deformation and plastic flow enhances molecular mobility leading to mixing of different domains in solid dispersions. Different manufacturing methods may result in products with similar free volume, thereby showing similar molecular mobility.
Directory of Open Access Journals (Sweden)
Guallar-Castillón Pilar
2011-06-01
Full Text Available Abstract Background Evidence on the relation between leisure-time physical activity (LTPA and health-related quality of life (HRQoL in older adults is based primarily on clinical trials of physical exercise programs in institutionalized persons and on cross-sectional studies of community-dwelling persons. Moreover, there is no evidence on whether leisure-time sedentary behavior (LTSB is associated with HRQoL independently of LTPA. This study examined the longitudinal association between LTPA, LTSB, and HRQoL in older community-dwelling adults in Spain. Methods Prospective cohort study of 1,097 persons aged 62 and over. In 2003 LTPA in MET-hr/week was measured with a validated questionnaire, and LTSB was estimated by the number of sitting hours per week. In 2009 HRQoL was measured with the SF-36 questionnaire. Analyses were done with linear regression and adjusted for the main confounders. Results Compared with those who did no LTPA, subjects in the upper quartile of LTPA had better scores on the SF-36 scales of physical functioning (β 5.65; 95% confidence interval [CI] 1.32-9.98; p linear trend Conclusions Greater LTPA and less LTSB were independently associated with better long-term HRQoL in older adults.
Time distributions in satellite constellation design
Arnas, David; Casanova, Daniel; Tresaco, Eva
2017-01-01
The aim of the time distribution methodology presented in this paper is to generate constellations whose satellites share a set of relative trajectories in a given time, and maintain that property over time without orbit corrections. The model takes into account a series of orbital perturbations such as the gravitational potential of the Earth, the atmospheric drag, the Sun and the Moon as disturbing third bodies and the solar radiation pressure. These perturbations are included in the design process of the constellation. Moreover, the whole methodology allows to design constellations with multiple relative trajectories that can be distributed in a minimum number of inertial orbits.
Smith, Erin; Walsh, Lorcan; Doyle, Julie; Greene, Barry; Blake, Catherine
2017-08-01
The Timed Up and Go test (TUG) is used as a measure of functional ability in older adults; however, the method of measurement does not allow us to determine which aspects of the test deficits occur in. The aim of the present study was to examine the ability of the quantitative TUG (QTUG) to measure performance during the TUG test under three different conditions - single task, motor task and cognitive dual task - and to compare performance between fallers and non-fallers in high-functioning community-dwelling older adults. A total of 37 community-dwelling older adults, 16 with a self-reported falls history in the previous year, were recruited. Participants underwent a falls risk assessment with a physiotherapist including the QTUG under three conditions (single task, motor task, cognitive dual-task). A total of 10 clinical parameters were chosen for analysis using mancova and a series of ancova, with age, sex and body mass index included as covariates. The mancova analysis showed a significant difference across the three task conditions (Wilk's Lambda F20,186 = 3.37, P time in double support. When faller and non-faller differences were explored, cadence and stride velocity was greater, and stride time longer in those with a prior history of falls. In community-dwelling older adults, these preliminary results show that a cognitive dual-task significantly (P time-to-stand observed with a motor task. Although no statistical difference was found between fallers and non-fallers for many of the parameters, cadence, stride time and stride velocity were statistically different (P < 0.05). A larger sample size and more assessment points might lead to more definitive findings. These results highlight the need for further research to examine QTUG performance under dual-task conditions between fallers and non-fallers in this population, and to look at the ability of dual-task QTUG assessment to measure change longitudinally and the effectiveness of therapeutic
Femtosecond Timing Distribution Using Optical Pulses
Winter, A; Winter, A
2005-01-01
Fourth-generation light sources, such as the European X-ray Free Electron Laser (XFEL) require timing signals distributed over distances of several kilometers with a stability in the order of femtoseconds. A promising approach is the use of a mode-locked laser that generates sub-picosecond pulses which are distributed in timing stabilized optical fiber links. A good candidate for a laser master oscillator (LMO) is a mode-locked Erbium-doped fiber laser, featuring extremely low phase noise far from the carrier. Results on the development of the LMO locked to an external reference microwave oscillator to suppress low frequency jitter, the distribution via timing stabilized optical fiber links and the reconversion of the optical pulses to a low phase noise microwave RF signals with overall femtosecond stability are presented.
Linking age, survival, and transit time distributions
Calabrese, Salvatore; Porporato, Amilcare
2015-10-01
Although the concepts of age, survival, and transit time have been widely used in many fields, including population dynamics, chemical engineering, and hydrology, a comprehensive mathematical framework is still missing. Here we discuss several relationships among these quantities by starting from the evolution equation for the joint distribution of age and survival, from which the equations for age and survival time readily follow. It also becomes apparent how the statistical dependence between age and survival is directly related to either the age dependence of the loss function or the survival-time dependence of the input function. The solution of the joint distribution equation also allows us to obtain the relationships between the age at exit (or death) and the survival time at input (or birth), as well as to stress the symmetries of the various distributions under time reversal. The transit time is then obtained as a sum of the age and survival time, and its properties are discussed along with the general relationships between their mean values. The special case of steady state case is analyzed in detail. Some examples, inspired by hydrologic applications, are presented to illustrate the theory with the specific results. This article was corrected on 11 Nov 2015. See the end of the full text for details.
Doshi, Mehul Harshad; Narayanan, Govindarajan
2016-12-01
Chronic post-thrombotic obstruction of the inferior vena cava (IVC) or iliocaval junction is an uncommon complication of long indwelling IVC filter. When such an obstruction is symptomatic, endovascular treatment options include stent placement with or without filter retrieval. Filter retrieval becomes increasingly difficult with longer dwell times. We present a case of symptomatic post-thrombotic obstruction of the iliocaval junction related to Günther-Tulip IVC filter (Cook Medical Inc, Bloomington, IN) with dwell time of 4753 days, treated successfully with endovascular filter removal and stent reconstruction. Filter retrieval and stent reconstruction may be a treatment option in symptomatic patients with filter-related chronic IVC or iliocaval junction obstruction, even after prolonged dwell time.
Time-dependent species sensitivity distributions.
Fox, David R; Billoir, Elise
2013-02-01
Time is a central component of toxicity assessments. However, current ecotoxicological practice marginalizes time in concentration-response (C-R) modeling and species sensitivity distribution (SSD) analyses. For C-R models, time is invariably fixed, and toxicity measures are estimated from a function fitted to the data at that time. The estimated toxicity measures are used as inputs to the SSD modeling phase, which similarly avoids explicit recognition of the temporal component. The present study extends some commonly employed probability models for SSDs to derive theoretical results that characterize the time-dependent nature of hazardous concentration (HCx) values. The authors' results show that even from very simple assumptions, more complex patterns in the SSD time dependency can be revealed.
Barry, Emma; Galvin, Rose; Keogh, Claire; Horgan, Frances; Fahey, Tom
2014-02-01
The Timed Up and Go test (TUG) is a commonly used screening tool to assist clinicians to identify patients at risk of falling. The purpose of this systematic review and meta-analysis is to determine the overall predictive value of the TUG in community-dwelling older adults. A literature search was performed to identify all studies that validated the TUG test. The methodological quality of the selected studies was assessed using the QUADAS-2 tool, a validated tool for the quality assessment of diagnostic accuracy studies. A TUG score of ≥13.5 seconds was used to identify individuals at higher risk of falling. All included studies were combined using a bivariate random effects model to generate pooled estimates of sensitivity and specificity at ≥13.5 seconds. Heterogeneity was assessed using the variance of logit transformed sensitivity and specificity. Twenty-five studies were included in the systematic review and 10 studies were included in meta-analysis. The TUG test was found to be more useful at ruling in rather than ruling out falls in individuals classified as high risk (>13.5 sec), with a higher pooled specificity (0.74, 95% CI 0.52-0.88) than sensitivity (0.31, 95% CI 0.13-0.57). Logistic regression analysis indicated that the TUG score is not a significant predictor of falls (OR = 1.01, 95% CI 1.00-1.02, p = 0.05). The Timed Up and Go test has limited ability to predict falls in community dwelling elderly and should not be used in isolation to identify individuals at high risk of falls in this setting.
Modeling utilization distributions in space and time.
Keating, Kim A; Cherry, Steve
2009-07-01
W. Van Winkle defined the utilization distribution (UD) as a probability density that gives an animal's relative frequency of occurrence in a two-dimensional (x, y) plane. We extend Van Winkle's work by redefining the UD as the relative frequency distribution of an animal's occurrence in all four dimensions of space and time. We then describe a product kernel model estimation method, devising a novel kernel from the wrapped Cauchy distribution to handle circularly distributed temporal covariates, such as day of year. Using Monte Carlo simulations of animal movements in space and time, we assess estimator performance. Although not unbiased, the product kernel method yields models highly correlated (Pearson's r = 0.975) with true probabilities of occurrence and successfully captures temporal variations in density of occurrence. In an empirical example, we estimate the expected UD in three dimensions (x, y, and t) for animals belonging to each of two distinct bighorn sheep (Ovis canadensis) social groups in Glacier National Park, Montana, USA. Results show the method can yield ecologically informative models that successfully depict temporal variations in density of occurrence for a seasonally migratory species. Some implications of this new approach to UD modeling are discussed.
Waiting time distributions in financial markets
Sabatelli, L.; Keating, S.; Dudley, J.; Richmond, P.
2002-05-01
We study waiting time distributions for data representing two completely different financial markets that have dramatically different characteristics. The first are data for the Irish market during the 19th century over the period 1850 to 1854. A total of 10 stocks out of a database of 60 are examined. The second database is for Japanese yen currency fluctuations during the latter part of the 20th century (1989-1992). The Irish stock activity was recorded on a daily basis and activity was characterised by waiting times that varied from one day to a few months. The Japanese yen data was recorded every minute over 24 hour periods and the waiting times varied from a minute to a an hour or so. For both data sets, the waiting time distributions exhibit power law tails. The results for Irish daily data can be easily interpreted using the model of a continuous time random walk first proposed by Montroll and applied recently to some financial data by Mainardi, Scalas and colleagues. Yen data show a quite different behaviour. For large waiting times, the Irish data exhibit a cut off; the Yen data exhibit two humps that could arise as result of major trading centres in the World.
Asymptotic Time Averages and Frequency Distributions
Directory of Open Access Journals (Sweden)
Muhammad El-Taha
2016-01-01
Full Text Available Consider an arbitrary nonnegative deterministic process (in a stochastic setting {X(t, t≥0} is a fixed realization, i.e., sample-path of the underlying stochastic process with state space S=(-∞,∞. Using a sample-path approach, we give necessary and sufficient conditions for the long-run time average of a measurable function of process to be equal to the expectation taken with respect to the same measurable function of its long-run frequency distribution. The results are further extended to allow unrestricted parameter (time space. Examples are provided to show that our condition is not superfluous and that it is weaker than uniform integrability. The case of discrete-time processes is also considered. The relationship to previously known sufficient conditions, usually given in stochastic settings, will also be discussed. Our approach is applied to regenerative processes and an extension of a well-known result is given. For researchers interested in sample-path analysis, our results will give them the choice to work with the time average of a process or its frequency distribution function and go back and forth between the two under a mild condition.
Directory of Open Access Journals (Sweden)
H. Bello-Villalobos
2006-06-01
Full Text Available Objetivo: Determinar los factores que inciden en el tiempo de permanencia de un catéter endovenoso central. Antecedentes: En el paciente con cáncer existen factores propios del estado de inmunocompromiso por el tumor y los efectos colaterales de su tratamiento que aumentan la probabilidad de infección y consecuentemente reducen el tiempo de uso de un catéter. Sujetos: Se integró una cohorte de 306 pacientes con cáncer, con una edad promedio de 59 ± 14,5 años. Intervenciones: Se definió tiempo cero como el día de colocación del catéter. Diariamente se buscaron signos clínicos de infección por catéter, con toma de hemocultivos simultáneos cada 7 días. El desenlace primario fue infección del catéter y el alternativo fin de tratamiento, obstrucción o fallecimiento del paciente. Se comparó el tiempo de permanencia del catéter infectado vs no infectado y su relación con factores de riesgo potenciales. Resultados: Se colocaron 306 catéteres para un total de 4.043 días/catéter. Se infectaron 25 (8,2%. La sobrevida media global fue de 50 días. Se encontró que a mayor tiempo de permanencia, mayor fue la incidencia de infección. En el análisis de sobrevida ajustado, la presencia de infección a distancia (OR = 4,71, IC95% = 1,7-10,1, p = 0,002 fue el factor que mostró una asociación significativa. Conclusiones: El tiempo de vida útil de un catéter es amplia, limitada por la presencia de infección a distancia como factor de riesgo potencial de infección por catéter.Objective: To determine the factors that affect the dwell time of a central venous catheter. Background: The own immunodeficiency in cancer patient and the collateral effects of their treatment increase the probability of infection and reduce the time of use of a catheter. Subjects: Incipient cohort of 306 patients with cancer, with an average age of 59 ± 14.5 years. Interventions: Time zero like the day of the placement of the catheter was defined. Daily
Vansteenkiste, Pieter; Cardon, Greet; Philippaerts, Renaat; Lenoir, Matthieu
2015-01-01
Although analysing software for eye-tracking data has significantly improved in the past decades, the analysis of gaze behaviour recorded with head-mounted devices is still challenging and time-consuming. Therefore, new methods have to be tested to reduce the analysis workload while maintaining accuracy and reliability. In this article, dwell time percentages to six areas of interest (AOIs), of six participants cycling on four different roads, were analysed both frame-by-frame and in a 'fixation-by-fixation' manner. The fixation-based method is similar to the classic frame-by-frame method but instead of assigning frames, fixations are assigned to one of the AOIs. Although some considerable differences were found between the two methods, a Pearson correlation of 0.930 points out a good validity of the fixation-by-fixation method. For the analysis of gaze behaviour over an extended period of time, the fixation-based approach is a valuable and time-saving alternative for the classic frame-by-frame analysis.
Measurement of dead time by time interval distribution method
Arkani, Mohammad; Raisali, Gholamreza
2015-02-01
Non-random event losses due to dead time effect in nuclear radiation detection systems distort the original Poisson process into a new type of distribution. As the characteristics of the distribution depend on physical properties of the detection system, it is possible to estimate the dead time parameters based on time interval analysis, this is the problem investigated in this work. A BF3 ionization chamber is taken as a case study to check the validity of the method in experiment. The results are compared with the data estimated by power rising experiment performed in Esfahan Heavy Water Zero Power Reactor (EHWZPR). Using Monte Carlo simulation, the problem is elaborately studied and useful range for counting rates of the detector is determined. The proposed method is accurate and applicable for all kinds of radiation detectors with no potential difficulty and no need for any especial nuclear facility. This is not a time consuming method and advanced capability of online examination during normal operation of the detection system is possible.
Transition Path Time Distribution, Tunneling Times, Friction, and Uncertainty
Pollak, Eli
2017-02-01
A quantum mechanical transition path time probability distribution is formulated and its properties are studied using a parabolic barrier potential model. The average transit time is well defined and readily calculated. It is smaller than the analogous classical mechanical average transit time, vanishing at the crossover temperature. It provides a direct route for determining tunneling times. The average time may be also used to define a coarse grained momentum of the system for the passage from one side of the barrier to the other. The product of the uncertainty in this coarse grained momentum with the uncertainty in the location of the particle is shown under certain conditions to be smaller than the ℏ/2 formal uncertainty limit. The model is generalized to include friction in the form of a bilinear interaction with a harmonic bath. Using an Ohmic friction model one finds that increasing the friction, increases the transition time. Only moderate values of the reduced friction coefficient are needed for the quantum transition time and coarse grained uncertainty to approach the classical limit which is smaller than ℏ/2 when the friction is not too small. These results show how one obtains classical dynamics from a pure quantum system without invoking any further assumptions, approximations, or postulates.
The CMS Timing Control and Distribution System
AUTHOR|(CDS)2075794; Andre, Jean-marc Olivier; Behrens, Ulf; Branson, James; Chaze, Olivier; Cittolin, Sergio; Darlea, Georgiana Lavinia; Deldicque, Christian; Demiragli, Zeynep; Dobson, Marc; Erhan, Samim; Fulcher, Jonathan Richard; Gigi, Dominique; Glege, Frank; Gomez Ceballos, Guillelmo; Hansen, Magnus; Holzner, Andre Georg; Jimenez Estupinan, Raul; Masetti, Lorenzo; Meijers, Franciscus; Meschi, Emilio; Mommsen, Remigius; Morovic, Srecko; O'Dell, Vivian; Orsini, Luciano; Paus, Christoph Maria Ernst; Pieri, Marco; Racz, Attila; Sakulin, Hannes; Schwick, Christoph; Simelevicius, Dainius; Troska, Jan; Vichoudis, Paschalis; Zejdl, Petr
2016-01-01
The Compact Muon Solenoid (CMS) experiment operating at the CERN (European Laboratory for Nuclear Physics) Large Hadron Collider (LHC) is in the process of upgrading several of its detector systems. Adding more individual detector components brings the need to test and commission those components separately from existing ones so as not to compromise physics data-taking. The CMS Trigger, Timing and Control (TTC) system had reached its limits in terms of the number of separate elements (partitions) that could be supported. A new Timing and Control Distribution System (TCDS) has been designed, built and commissioned in order to overcome this limit. It also brings additional functionality to facilitate parallel commissioning of new detector elements. We describe the new TCDS system and its components and show results from the first operational experience with the TCDS system in CMS.
DEFF Research Database (Denmark)
Welling, Helen; Duelund Mortensen, Peder; Wiell Nordberg, Lene
2006-01-01
values and needs in differnet situations, lifestyles and stages. The study is based on information from users in new housing schemes in and around Copenhagen - 'open building' dwellings that reveal a variety of approaches to these problems? The analysis of the dwellings show that the architecture...... of the 'open dwelling' is dependent on three basic conditions: the static condition, the suitable condition and the situational condition. Each condition has its own powerful way of articulation. Our aim is to translate the observations of the projects in concepts and models that are applicable in new projects....
Wijlhuizen, G.J.; Chorus, A.M.J.; Hopman-Rock, M.
2008-01-01
Objectives: Most research on falls among older persons focuses on health-related factors that affect the ability to maintain balance. The objective of the study is to determine the association between physical activity and occurrence of falls among community-dwelling older persons. Methods: The dist
Waiting time distribution for continuous stochastic systems.
Gernert, Robert; Emary, Clive; Klapp, Sabine H L
2014-12-01
The waiting time distribution (WTD) is a common tool for analyzing discrete stochastic processes in classical and quantum systems. However, there are many physical examples where the dynamics is continuous and only approximately discrete, or where it is favourable to discuss the dynamics on a discretized and a continuous level in parallel. An example is the hindered motion of particles through potential landscapes with barriers. In the present paper we propose a consistent generalization of the WTD from the discrete case to situations where the particles perform continuous barrier crossing characterized by a finite duration. To this end, we introduce a recipe to calculate the WTD from the Fokker-Planck (Smoluchowski) equation. In contrast to the closely related first passage time distribution (FPTD), which is frequently used to describe continuous processes, the WTD contains information about the direction of motion. As an application, we consider the paradigmatic example of an overdamped particle diffusing through a washboard potential. To verify the approach and to elucidate its numerical implications, we compare the WTD defined via the Smoluchowski equation with data from direct simulation of the underlying Langevin equation and find full consistency provided that the jumps in the Langevin approach are defined properly. Moreover, for sufficiently large energy barriers, the WTD defined via the Smoluchowski equation becomes consistent with that resulting from the analytical solution of a (two-state) master equation model for the short-time dynamics developed previously by us [Phys. Rev. E 86, 061135 (2012)]. Thus, our approach "interpolates" between these two types of stochastic motion. We illustrate our approach for both symmetric systems and systems under constant force.
DEFF Research Database (Denmark)
Bloch, Mette L; Jønsson, Line R; Kristensen, Morten T
2016-01-01
BACKGROUND AND PURPOSE: Originally, the Timed Up & Go (TUG) test was described as including a practice trial before a timed trial, but recent studies in individuals with hip fracture have reported that performance improved with a third trial and that high intertester reliability was achieved when...
Acoustic classification of dwellings
DEFF Research Database (Denmark)
Berardi, Umberto; Rasmussen, Birgit
2014-01-01
Schemes for the classification of dwellings according to different building performances have been proposed in the last years worldwide. The general idea behind these schemes relates to the positive impact a higher label, and thus a better performance, should have. In particular, focusing on soun...... exchanging experiences about constructions fulfilling different classes, reducing trade barriers, and finally increasing the sound insulation of dwellings.......Schemes for the classification of dwellings according to different building performances have been proposed in the last years worldwide. The general idea behind these schemes relates to the positive impact a higher label, and thus a better performance, should have. In particular, focusing on sound...... insulation performance, national schemes for sound classification of dwellings have been developed in several European countries. These schemes define acoustic classes according to different levels of sound insulation. Due to the lack of coordination among countries, a significant diversity in terms...
Makizako, Hyuma; Shimada, Hiroyuki; Doi, Takehiko; Tsutsumimoto, Kota; Nakakubo, Sho; Hotta, Ryo; Suzuki, Takao
2017-04-01
Lower extremity functioning is important for maintaining activity in elderly people. Optimal cutoff points for standard measurements of lower extremity functioning would help identify elderly people who are not disabled but have a high risk of developing disability. The purposes of this study were: (1) to determine the optimal cutoff points of the Five-Times Sit-to-Stand Test and the Timed "Up & Go" Test for predicting the development of disability and (2) to examine the impact of poor performance on both tests on the prediction of the risk of disability in elderly people dwelling in the community. This was a prospective cohort study. A population of 4,335 elderly people dwelling in the community (mean age = 71.7 years; 51.6% women) participated in baseline assessments. Participants were monitored for 2 years for the development of disability. During the 2-year follow-up period, 161 participants (3.7%) developed disability. The optimal cutoff points of the Five-Times Sit-to-Stand Test and the Timed "Up & Go" Test for predicting the development of disability were greater than or equal to 10 seconds and greater than or equal to 9 seconds, respectively. Participants with poor performance on the Five-Times Sit-to-Stand Test (hazard ratio = 1.88; 95% CI = 1.11-3.20), the Timed "Up & Go" Test (hazard ratio = 2.24; 95% CI = 1.42-3.53), or both tests (hazard ratio = 2.78; 95% CI = 1.78-4.33) at the baseline assessment had a significantly higher risk of developing disability than participants who had better lower extremity functioning. All participants had good initial functioning and participated in assessments on their own. Causes of disability were not assessed. Assessments of lower extremity functioning with the Five-Times Sit-to-Stand Test and the Timed "Up & Go" Test, especially poor performance on both tests, were good predictors of future disability in elderly people dwelling in the community.
Smith, Erin; Walsh, Lorcan; Doyle, Julie; Greene, Barry; Blake, Catherine
2016-01-01
The timed up and go (TUG) test is a commonly used assessment in older people with variations including the addition of a motor or cognitive dual-task, however in high functioning older adults it is more difficult to assess change. The quantified TUG (QTUG) uses inertial sensors to detect test and gait parameters during the test. If it is to be used in the longitudinal assessment of older adults, it is important that we know which parameters are reliable and under which conditions. This study aims to examine the relative reliability of the QTUG over five consecutive days under single, motor and cognitive dual-task conditions. Twelve community dwelling older adults (10 females, mean age 74.17 (3.88)) performed the QTUG under three conditions for five consecutive days. The relative reliability of each of the gait parameters was assessed using intra-class correlation coefficient (ICC 3,1) and standard error of measurement (SEM). Five of the measures demonstrated excellent reliability (ICC>0.70) under all three conditions (time to complete test, walk time, number of gait cycles, number of steps and return from turn time). Measures of variability and turn derived parameters demonstrated weak reliability under all three conditions (ICC=0.05-0.49). For the most reliable parameters under single-task conditions, the addition of a cognitive task resulted in a reduction in reliability suggesting caution when interpreting results under these conditions. Certain sensor derived parameters during the QTUG test may provide an additional resource in the longitudinal assessment of older people and earlier identification of falls risk.
Kojima, Gotaro; Masud, Tahir; Kendrick, Denise; Morris, Richard; Gawler, Sheena; Treml, Jonathan; Iliffe, Steve
2015-04-03
Falling is common among older people. The Timed-Up-and-Go Test (TUG) is recommended as a screening tool for falls but its predictive value has been challenged. The objectives of this study were to examine the ability of TUG to predict future falls and to estimate the optimal cut-off point to identify those with higher risk for future falls. This is a prospective cohort study nested within a randomised controlled trial including 259 British community-dwelling older people ≥65 years undergoing usual care. TUG was measured at baseline. Prospective diaries captured falls over 24 weeks. A Receiver Operating Characteristic curve analysis determined the optimal cut-off point to classify future falls risk with sensitivity, specificity, and predictive values of TUG times. Logistic regression models examined future falls risk by TUG time. Sixty participants (23%) fell during the 24 weeks. The area under the curve was 0.58 (95% confidence interval (95% CI) = 0.49-0.67, p = 0.06), suggesting limited predictive value. The optimal cut-off point was 12.6 seconds and the corresponding sensitivity, specificity, and positive and negative predictive values were 30.5%, 89.5%, 46.2%, and 81.4%. Logistic regression models showed each second increase in TUG time (adjusted for age, gender, comorbidities, medications and past history of two falls) was significantly associated with future falls (adjusted odds ratio (OR) = 1.09, 95% CI = 1.00-1.19, p = 0.05). A TUG time ≥12.6 seconds (adjusted OR = 3.94, 95% CI = 1.69-9.21, p = 0.002) was significantly associated with future falls, after the same adjustments. TUG times were significantly and independently associated with future falls. The ability of TUG to predict future falls was limited but with high specificity and negative predictive value. TUG may be most useful in ruling in those with a high risk of falling rather than as a primary measure in the ascertainment of risk.
Sound Insulation between Dwellings
DEFF Research Database (Denmark)
Rasmussen, Birgit
2011-01-01
Regulatory sound insulation requirements for dwellings exist in more than 30 countries in Europe. In some countries, requirements have existed since the 1950s. Findings from comparative studies show that sound insulation descriptors and requirements represent a high degree of diversity...... and initiate – where needed – improvement of sound insulation of new and existing dwellings in Europe to the benefit of the inhabitants and the society. A European COST Action TU0901 "Integrating and Harmonizing Sound Insulation Aspects in Sustainable Urban Housing Constructions", has been established and runs...... 2009-2013. The main objectives of TU0901 are to prepare proposals for harmonized sound insulation descriptors and for a European sound classification scheme with a number of quality classes for dwellings. Findings from the studies provide input for the discussions in COST TU0901. Data collected from 24...
Sound insulation between dwellings
DEFF Research Database (Denmark)
Rasmussen, Birgit
2011-01-01
Regulatory sound insulation requirements for dwellings exist in more than 30 countries in Europe. In some countries, requirements have existed since the 1950s. Findings from comparative studies show that sound insulation descriptors and requirements represent a high degree of diversity...... and initiate – where needed – improvement of sound insulation of new and existing dwellings in Europe to the benefit of the inhabitants and the society. A European COST Action TU0901 "Integrating and Harmonizing Sound Insulation Aspects in Sustainable Urban Housing Constructions", has been established and runs...... 2009-2013. The main objectives of TU0901 are to prepare proposals for harmonized sound insulation descriptors and for a European sound classification scheme with a number of quality classes for dwellings. Findings from the studies provide input for the discussions in COST TU0901. Data collected from 24...
Chen, Hui-Ya; Tang, Pei-Fang
2016-03-01
Dual-task Timed "Up & Go" (TUG) tests are likely to have applications different from those of a single-task TUG test and may have different contributing factors. The purpose of this study was to compare factors contributing to performance on single- and dual-task TUG tests. This investigation was a cross-sectional study. Sixty-four adults who were more than 50 years of age and dwelled in the community were recruited. Interviews and physical examinations were performed to identify potential contributors to TUG test performance. The time to complete the single-task TUG test (TUGsingle) or the dual-task TUG test, which consisted of completing the TUG test while performing a serial subtraction task (TUGcognitive) or while carrying water (TUGmanual), was measured. Age, hip extensor strength, walking speed, general mental function, and Stroop scores for word and color were significantly associated with performance on all TUG tests. Hierarchical multiple regression models, without the input of walking speed, revealed different independent factors contributing to TUGsingle performance (Mini-Mental Status Examination score, β=-0.32), TUGmanual performance (age, β=0.35), and TUGcognitive performance (Stroop word score, β=-0.40; Mini-Mental Status Examination score, β=-0.31). At least 40% of the variance in the performance on the 3 TUG tests was not explained by common clinical measures, even when the factor of walking speed was considered. However, this study successfully identified some important factors contributing to performance on different TUG tests, and other studies have reported similar findings for single-task TUG test and dual-task gait performance. Although the TUGsingle and the TUGcognitive shared general mental function as a common factor, the TUGmanual was uniquely influenced by age and the TUGcognitive was uniquely influenced by focused attention. These results suggest that both common and unique factors contribute to performance on single- and dual
Dwelling Water Tanks in Diyarbakir
Directory of Open Access Journals (Sweden)
Ali Ceylan
2008-02-01
Full Text Available BACKGROUND: In this connection, the object of this study has been to identify and compare the microbiological contamination and residue chlorine levels in the main network water that is taken from the Dicle Dam and distributed in Diyarbakir Province Centre and in the tanks of dwellings that use this water as well as the effects of the maintenance, hygiene, and physical conditions of these tanks on microbiological contamination. METHODS: Water samples were taken from both the tank input side network water and tank output side tank waters of 200 dwellings with water tanks in Diyarbakir city centre (tank entrance network side water for 200 and tank output side tank water for 200 within the framework of the research study. RESULTS: Coliform bacteria were detected in 35% of the tank entrance side network water samples and in 52.0% percent of the tank output side water samples. Faecal coliform bacteria were not detected in tank entrance side network water samples, but they existed in 2.5% of the tank output side water samples. Free residue chlorine level was found to be over 0.2 ppm in 67% of tank entrance side network water samples and in 35% of the tank output side water samples. Coliform bacteria were detected in 95.5% of the tank entrance side network water samples, of which free residue chlorine level were below 0.2 ppm. Total germ growth was detected in 52.0% of the tank entrance side network water samples and in 67.5% of the tank output side water samples. The most frequently isolated bacteria both in tank entrance side network and tank output side water samples were found to be Bacillus spp. Bacillus type bacteria were found in 48% of tank entrance side network water samples and 57.5% of the tank output side water samples. Filamentous fungi were prevalent in 8% of all the samples examined within the study and the most commonly isolated filamentous fungi were Aspergillus spp (5.5% and Penicillum spp (2.5%. Water tanks of dwellings contain more
Catchment mixing processes and travel time distributions
National Research Council Canada - National Science Library
Botter, Gianluca
2012-01-01
...) of travel, residence and evapotranspiration times, which are comprehensive descriptors of the fate of rainfall water particles traveling through catchments, and provide key information on hydrologic...
Optimal distribution of measurement time in single channel measurements
Kaspar, J
2008-01-01
Single channel measurements play a minor role in today physics, but they are sometimes unavoidable. Comparing to multichannel measurements, there is distribution of measurement time to be chosen in an experiment design. A method to optimize distribution of measurement time is given, where optimal distribution minimizes standard deviation of a selected fit parameter. As an example, the method is applied to electron spectroscopy experiments.
Design a Fault Tolerance for Real Time Distributed System
Ban M. Khammas
2012-01-01
This paper designed a fault tolerance for soft real time distributed system (FTRTDS). This system is designed to be independently on specific mechanisms and facilities of the underlying real time distributed system. It is designed to be distributed on all the computers in the distributed system and controlled by a central unit.Besides gathering information about a target program spontaneously, it provides information about the target operating system and the target hardware in order to diagno...
Origin and Nonuniversality of the Earthquake Interevent Time Distribution
Touati, Sarah; Naylor, Mark; Main, Ian G.
2009-04-01
Many authors have modeled regional earthquake interevent times using a gamma distribution, whereby data collapse occurs under a simple rescaling of the data from different regions or time periods. We show, using earthquake data and simulations, that the distribution is fundamentally a bimodal mixture distribution dominated by correlated aftershocks at short waiting times and independent events at longer times. The much-discussed power-law segment often arises as a crossover between these two. We explain the variation of the distribution with region size and show that it is not universal.
The Origin of the Solar Flare Waiting-Time Distribution
Wheatland, M S
2000-01-01
It was recently pointed out that the distribution of times between solar flares (the flare waiting-time distribution) follows a power law, for long waiting times. Based on 25 years of soft X-ray flares observed by Geostationary Operational Environmental Satellite (GOES) instruments it is shown that 1. the waiting-time distribution of flares is consistent with a time-dependent Poisson process, and 2. the fraction of time the Sun spends with different flaring rates approximately follows an exponential distribution. The second result is a new phenomenological law for flares. It is shown analytically how the observed power-law behavior of the waiting times originates in the exponential distribution of flaring rates. These results are argued to be consistent with a non-stationary avalanche model for flares.
Distribution of time between unscheduled outages
Energy Technology Data Exchange (ETDEWEB)
Jaech, J.L.; Burke, R.C.
1963-01-02
A study is in progress in which reactor operations will be simulated on the computer, the primary purpose being to evaluate the costs associated with various administrative alternatives which may be followed in conducting the overall operation, in addition to defining how operational costs are affected by such things as changes in fuel quality. The problem is complicated by the fact that the operation of the reactors is largely affected by random occurrences; no one can predict exactly when a tube will leak, or when a rupture will occur. Therefore, basic to the study is a probabilistic function, or set of functions, which govern the random aspects of reactor outages, and which can be used in the simulation study to generate reactor outages. This report is concerned with the derivation of such probabilistic functions. Although derived specifically for the simulation study, they are deemed of sufficient interest to warrant a separate report. Similar documents will be issued from time to time as the study progresses, and as results are found which are considered worthy of reporting prior to completion of the study.
Aoki, Shigeru; Uchiyama, Jumpei; Ito, Manabu
2014-06-01
Differences between laboratory and commercial tablet presses are frequently observed during scale-up of tableting process. These scale-up issues result from the differences in total compression time that is the sum of consolidation and dwell times. When a lubricated blend is compressed into tablets, the tablet thickness produced by the commercial tablet press is often thicker than that by a laboratory tablet press. A new punch shape design, designated as shape adjusted for scale-up (SAS), was developed and used to demonstrate the ability to replicate scale-up issues in commercial-scale tableting processes. It was found that the consolidation time can be slightly shortened by changing the vertical curvature of the conventional punch head rim. However, this approach is not enough to replicate the consolidation time. A secondary two-stage SAS punch design and an embossed punch head was designed to replicate the consolidation and dwell times on a laboratory tablet press to match those of a commercial tablet press. The resulting tablet thickness using this second SAS punch on a laboratory tablet press was thicker than when using a conventional punch in the same laboratory tablet press. The secondary SAS punches are more useful tools for replicating and understanding potential scale-up issues. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.
Charged fluid distribution in higher dimensional spheroidal space-time
Indian Academy of Sciences (India)
G P Singh; S Kotambkar
2005-07-01
A general solution of Einstein field equations corresponding to a charged fluid distribution on the background of higher dimensional spheroidal space-time is obtained. The solution generates several known solutions for superdense star having spheroidal space-time geometry.
Distributed Time Delay Goodwin's Models of the Business Cycle
Antonova, A. O.; Reznik, S. N.; Todorov, M. D.
2011-11-01
We consider continuously distributed time delay Goodwin's model of the business cycle. We show that the delay induced sawtooth oscillations, similar to those detected by R. H. Strotz, J. C. McAnulty, J. B. Naines, Econometrica, 21, 390-411 (1953) for Goodwin's model with fixed investment time lag, exist only for very narrow delay distribution when the variance of the delay distribution much less than the average delay.
Acoustic classification of dwellings
DEFF Research Database (Denmark)
Berardi, Umberto; Rasmussen, Birgit
2014-01-01
insulation performance, national schemes for sound classification of dwellings have been developed in several European countries. These schemes define acoustic classes according to different levels of sound insulation. Due to the lack of coordination among countries, a significant diversity in terms...... of descriptors, number of classes, and class intervals occurred between national schemes. However, a proposal “acoustic classification scheme for dwellings” has been developed recently in the European COST Action TU0901 with 32 member countries. This proposal has been accepted as an ISO work item. This paper...
Provably secure time distribution for the electric grid
Energy Technology Data Exchange (ETDEWEB)
Smith IV, Amos M [ORNL; Evans, Philip G [ORNL; Williams, Brian P [ORNL; Grice, Warren P [ORNL
2015-01-01
We demonstrate a quantum time distribution (QTD) method that combines the precision of optical timing techniques with the integrity of quantum key distribution (QKD). Critical infrastructure is dependent on microprocessor- and programmable logic-based monitoring and control systems. The distribution of timing information across the electric grid is accomplished by GPS signals which are known to be vulnerable to spoofing. We demonstrate a method for synchronizing remote clocks based on the arrival time of photons in a modifed QKD system. This has the advantage that the signal can be veried by examining the quantum states of the photons similar to QKD.
Sensor Distribution Design of Travel Time Tomography in Explosion
Directory of Open Access Journals (Sweden)
Yali Guo
2014-07-01
Full Text Available Optimal sensor distribution in explosion testing is important in saving test costs and improving experiment efficiency. Aiming at travel time tomography in an explosion, an optimizing method in sensor distribution is proposed to improve the inversion stability. The influence factors of inversion stability are analyzed and the evaluating function on optimizing sensor distribution is proposed. This paper presents a sub-region and multi-scale cell partition method, according to the characteristics of a shock wave in an explosion. An adaptive escaping particle swarm optimization algorithm is employed to achieve the optimal sensor distribution. The experimental results demonstrate that optimal sensor distribution has improved both indexes and inversion stability.
Sensor distribution design of travel time tomography in explosion.
Guo, Yali; Han, Yan; Wang, Liming; Liu, Linmao
2014-07-15
Optimal sensor distribution in explosion testing is important in saving test costs and improving experiment efficiency. Aiming at travel time tomography in an explosion, an optimizing method in sensor distribution is proposed to improve the inversion stability. The influence factors of inversion stability are analyzed and the evaluating function on optimizing sensor distribution is proposed. This paper presents a sub-region and multi-scale cell partition method, according to the characteristics of a shock wave in an explosion. An adaptive escaping particle swarm optimization algorithm is employed to achieve the optimal sensor distribution. The experimental results demonstrate that optimal sensor distribution has improved both indexes and inversion stability.
Model for the distribution of aftershock interoccurrence times.
Shcherbakov, Robert; Yakovlev, Gleb; Turcotte, Donald L; Rundle, John B
2005-11-18
In this work the distribution of interoccurrence times between earthquakes in aftershock sequences is analyzed and a model based on a nonhomogeneous Poisson (NHP) process is proposed to quantify the observed scaling. In this model the generalized Omori's law for the decay of aftershocks is used as a time-dependent rate in the NHP process. The analytically derived distribution of interoccurrence times is applied to several major aftershock sequences in California to confirm the validity of the proposed hypothesis.
Investigating the distribution of the value of travel time savings
DEFF Research Database (Denmark)
Fosgerau, Mogens
2006-01-01
The distribution of the value of travel time savings (VTTS) is investigated employing various nonparametric techniques to a large dataset originating from a stated choice experiment. The data contain choices between a fast and more expensive alternative and a slow and less expensive alternative....... Increasing the implicit price of time leads to an increased share of respondents who decline to pay to save time. But a significant proportion of respondents, 13%, remain willing to pay to save time at the highest price of time in the design. This means that the right tail of the VTTS distribution...... is not observed and hence the mean VTTS cannot be evaluated without additional assumptions. When socio-economic and situational variables are introduced into a semiparametric model it becomes possible to accept that the whole VTTS distribution is observed. Sixteen candidates for parametric VTTS distributions...
Boucherie, Quentin; Gentile, Gaëtan; Chalançon, Coralie; Sciortino, Vincent; Blin, Olivier; Micallef, Joëlle; Bonin-Guillaume, Sylvie
2017-01-01
The aim of this study was to assess the prevalence of long-term antipsychotic (AP) use in community-dwelling patients with dementia considering hospitalization periods as AP exposure or not. A retrospective study was carried out from 2009 to 2012 on a PACA-Alzheimer cohort (which included 31 963 patients in 2009 and 36 442 in 2012 from 5 million inhabitants). Three groups of patients were identified according to the longest exposure to APs without interruption: nonusers, short-term users (≤3 successive months without discontinuation), and long-term users. Sensitivity analyses on hospitalization periods were carried out. The percentage of patients with at least one AP dispensing was stable over the study period (25.6% in 2009 vs. 26.5% in 2012). In 2012, 27.6% were AP long-term users. This increased to 46.7% when hospitalization periods were counted as AP exposure. In comparison with nonusers, AP users took more benzodiazepines and antidepressants. Short-term users were men [odds ratio (OR)=1.2, 95% confidence interval (CI) (1.1-1.3)] older than 85 years old [OR=1.2, 95% CI (1.1-1.2)]. Long-term users were more exposed to benzodiazepines [OR=1.2, 95% CI (1.1-1.4)]. This study showed that long-term use of AP remained frequent in community-dwelling patients with dementia. It also showed that the prevalence of long-term users almost doubled when hospitalization periods were counted as AP exposure. This underlines the need to consider hospitalization periods when assessing medication exposure in populations with frequent periods of hospitalization.
Response Time Analysis of Distributed Web Systems Using QPNs
Directory of Open Access Journals (Sweden)
Tomasz Rak
2015-01-01
Full Text Available A performance model is used for studying distributed Web systems. Performance evaluation is done by obtaining load test measurements. Queueing Petri Nets formalism supports modeling and performance analysis of distributed World Wide Web environments. The proposed distributed Web systems modeling and design methodology have been applied in the evaluation of several system architectures under different external loads. Furthermore, performance analysis is done to determine the system response time.
Distributed energy storage: Time-dependent tree flow design
Bejan, A.; Ziaei, S.; Lorente, S.
2016-05-01
This article proposes "distributed energy storage" as a basic design problem of distributing energy storage material on an area. The energy flows by fluid flow from a concentrated source to points (users) distributed equidistantly on the area. The flow is time-dependent. Several scenarios are analyzed: sensible-heat storage, latent-heat storage, exergy storage vs energy storage, and the distribution of a finite supply of heat transfer surface between the source fluid and the distributed storage material. The chief conclusion is that the finite amount of storage material should be distributed proportionally with the distribution of the flow rate of heating agent arriving on the area. The total time needed by the source stream to "invade" the area is cumulative (the sum of the storage times required at each storage site) and depends on the energy distribution paths and the sequence in which the users are served by the source stream. Directions for future designs of distributed storage and retrieval are outlined in the concluding section.
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...
Waiting time distribution in M/D/1 queueing systems
DEFF Research Database (Denmark)
Iversen, Villy Bæk; Staalhagen, Lars
1999-01-01
The well-known formula for the waiting time distribution of M/D/1 queueing systems is numerically unsuitable when the load is close to 1.0 and/or the results for a large waiting time are required. An algorithm for any load and waiting time is presented, based on the state probabilities of M/D/1...
Valuing travel time variability: Characteristics of the travel time distribution on an urban road
DEFF Research Database (Denmark)
Fosgerau, Mogens; Fukuda, Daisuke
2012-01-01
This paper provides a detailed empirical investigation of the distribution of travel times on an urban road for valuation of travel time variability. Our investigation is premised on the use of a theoretical model with a number of desirable properties. The definition of the value of travel time...... variability depends on certain properties of the distribution of random travel times that require empirical verification. Applying a range of nonparametric statistical techniques to data giving minute-by-minute travel times for a congested urban road over a period of five months, we show that the standardized...... travel time is roughly independent of the time of day as required by the theory. Except for the extreme right tail, a stable distribution seems to fit the data well. The travel time distributions on consecutive links seem to share a common stability parameter such that the travel time distribution...
A Flexible Logistics Distribution Hub Model considering Cost Weighted Time
Directory of Open Access Journals (Sweden)
Wenxue Ran
2017-01-01
Full Text Available The delivery time of order has become an important fact for customers to evaluate logistics services. Due to the diverse and large quantities of orders in the background of electronic commerce, how to improve the flexibility of distribution hub and reduce the waiting time of customers becomes one of the most challenging questions for logistics companies. With this in mind, this paper proposes a new method of flexibility assessment in distribution hub by introducing cost weighted time (CWT. The advantages of supply hub operation mode in delivery flexibility are verified by the approach: the mode has pooling effects and uniform distribution characteristics; these traits can reduce overlapping delivery time to improve the flexibility in the case of two suppliers. Numerical examples show that the supply hub operation mode is more flexible than decentralized distribution operation mode in multidelivery cycles.
Classification of EEG Signals Using Adaptive Time-Frequency Distributions
Directory of Open Access Journals (Sweden)
Khan Nabeel A.
2016-06-01
Full Text Available Time-Frequency (t-f distributions are frequently employed for analysis of new-born EEG signals because of their non-stationary characteristics. Most of the existing time-frequency distributions fail to concentrate energy for a multicomponent signal having multiple directions of energy distribution in the t-f domain. In order to analyse such signals, we propose an Adaptive Directional Time-Frequency Distribution (ADTFD. The ADTFD outperforms other adaptive kernel and fixed kernel TFDs in terms of its ability to achieve high resolution for EEG seizure signals. It is also shown that the ADTFD can be used to define new time-frequency features that can lead to better classification of EEG signals, e.g. the use of the ADTFD leads to 97.5% total accuracy, which is by 2% more than the results achieved by the other methods.
Prediction of residence time distributions in food processing machinery
DEFF Research Database (Denmark)
Karlson, Torben; Friis, Alan; Szabo, Peter
1996-01-01
The velocity field in a co-rotating disc scraped surface heat exchanger (CDHE) is calculated using a finite element method. The residence time distribution for the CDHE is then obtained by tracing particles introduced in the inlet.......The velocity field in a co-rotating disc scraped surface heat exchanger (CDHE) is calculated using a finite element method. The residence time distribution for the CDHE is then obtained by tracing particles introduced in the inlet....
Prediction of residence time distributions in food processing machinery
DEFF Research Database (Denmark)
Karlson, Torben; Friis, Alan; Szabo, Peter
1996-01-01
The velocity field in a co-rotating disc scraped surface heat exchanger (CDHE) is calculated using a finite element method. The residence time distribution for the CDHE is then obtained by tracing particles introduced in the inlet.......The velocity field in a co-rotating disc scraped surface heat exchanger (CDHE) is calculated using a finite element method. The residence time distribution for the CDHE is then obtained by tracing particles introduced in the inlet....
Moreira, Bruno de Souza; Dos Anjos, Daniela Maria da Cruz; Pereira, Daniele Sirineu; Sampaio, Rosana Ferreira; Pereira, Leani Souza Máximo; Dias, Rosângela Corrêa; Kirkwood, Renata Noce
2016-03-03
Fear of falling is a common and potentially disabling problem among older adults. However, little is known about this condition in older adults with diabetes mellitus. The aims of this study were to investigate the impact of the fear of falling on clinical, functional and gait variables in older women with type 2 diabetes and to identify which variables could predict the fear of falling in this population. Ninety-nine community-dwelling older women with type 2 diabetes (aged 65 to 89 years) were stratified in two groups based on their Falls Efficacy Scale-International score. Participants with a score Timed Up and Go test (TUG), the five times sit-to-stand test (5-STS) and handgrip strength. Gait parameters were obtained using the GAITRite® system. Participants with a fear of falling were frailer and presented more depressive symptoms and worse performance on the TUG and 5-STS tests compared with those without a fear of falling. The group with the fear of falling also walked with a lower velocity, cadence and step length and increased step time and swing time variability. The multivariate regression analysis showed that the likelihood of having a fear of falling increased 1.34 times (OR 1.34, 95 % CI 1.11-1.61) for a one-point increase in the Geriatric Depression Scale (GDS-15) score and 1.36 times (OR 1.36, 95 % CI 1.07-1.73) for each second of increase in the TUG performance. The fear of falling in community-dwelling older women with type 2 diabetes mellitus is associated with frailty, depressive symptoms and dynamic balance, functional mobility and gait deficits. Furthermore, both the GDS-15 and the TUG test predict a fear of falling in this population. Therefore, these instruments should be considered during the assessment of diabetic older women with fear of falling.
Sound classification of dwellings
DEFF Research Database (Denmark)
Rasmussen, Birgit
2012-01-01
dwellings, facade sound insulation and installation noise. The schemes have been developed, implemented and revised gradually since the early 1990s. However, due to lack of coordination between countries, there are significant discrepancies, and new standards and revisions continue to increase the diversity....... Descriptors, range of quality levels, number of quality classes, class intervals, denotations and descriptions vary across Europe. The diversity is an obstacle for exchange of experience about constructions fulfilling different classes, implying also trade barriers. Thus, a harmonized classification scheme...... is needed, and a European COST Action TU0901 "Integrating and Harmonizing Sound Insulation Aspects in Sustainable Urban Housing Constructions", has been established and runs 2009-2013, one of the main objectives being to prepare a proposal for a European sound classification scheme with a number of quality...
Directory of Open Access Journals (Sweden)
Tiago S. Alexandre
2012-10-01
Full Text Available OBJECTIVE: To determine the accuracy of the Timed Up and Go Test (TUGT for screening the risk of falls among community-dwelling elderly individuals. METHOD: This is a prospective cohort study with a randomly by lots without reposition sample stratified by proportional partition in relation to gender involving 63 community-dwelling elderly individuals. Elderly individuals who reported having Parkinson's disease, a history of transitory ischemic attack, stroke and with a Mini Mental State Exam lower than the expected for the education level, were on a wheelchair and that reported a single fall in the previous six months were excluded. The TUGT, a mobility test, was the measure of interested and the occurrence of falls was the outcome. The performance of basic activities of daily living (ADL and instrumental activities of daily living (IADL was determined through the Older American Resources and Services, and the socio-demographic and clinical data were determined through the use of additional questionnaires. Receiver Operating Characteristic Curves were used to analyze the sensitivity and specificity of the TUGT. RESULTS: Elderly individuals who fell had greater difficulties in ADL and IADL (pOBJETIVO: Determinar a acurácia do Timed Up and Go Test (TUGT para rastrear risco de quedas em idosos da comunidade. MÉTODO: Trata-se de um estudo de coorte prospectivo com amostra sorteada aleatoriamente, sem reposição e estratificada por partilha proporcional em relação ao sexo de 63 idosos da comunidade. Excluíram-se idosos com doença de Parkinson, ataque isquêmico transitório, acidente vascular encefálico, Miniexame do Estado Mental inferior ao considerado normal de acordo com a escolaridade, movimentação exclusiva por cadeira de rodas e relato de uma queda nos seis meses anteriores à primeira entrevista. O TUGT, um teste de mobilidade, foi a medida testada, e o desfecho, a ocorrência de queda. Mensuraram-se atividades básicas (ABVD e
Real Time Synchronization for Creativity in Distributed Innovation Teams
DEFF Research Database (Denmark)
Peitersen, Dennis Kjaersgaard; Dolog, Peter; Pedersen, Esben Staunsbjerg
2009-01-01
In this paper we introduce a synchronization approach for real time collaborative sketching for creativity in distributed innovation teams. We base our approach on reverse AJAX. This way we ensure scalable solution for real time drawing and sketching important in creativity settings.......In this paper we introduce a synchronization approach for real time collaborative sketching for creativity in distributed innovation teams. We base our approach on reverse AJAX. This way we ensure scalable solution for real time drawing and sketching important in creativity settings....
Real Time Synchronization for Creativity in Distributed Innovation Teams
DEFF Research Database (Denmark)
Peitersen, Dennis Kjaersgaard; Dolog, Peter; Pedersen, Esben Staunsbjerg
2009-01-01
In this paper we introduce a synchronization approach for real time collaborative sketching for creativity in distributed innovation teams. We base our approach on reverse AJAX. This way we ensure scalable solution for real time drawing and sketching important in creativity settings.......In this paper we introduce a synchronization approach for real time collaborative sketching for creativity in distributed innovation teams. We base our approach on reverse AJAX. This way we ensure scalable solution for real time drawing and sketching important in creativity settings....
Determining prescription durations based on the parametric waiting time distribution
DEFF Research Database (Denmark)
Støvring, Henrik; Pottegård, Anton; Hallas, Jesper
2016-01-01
). When the IAD consisted of a mixture of two Log-Normal distributions, but was analyzed with a single Log-Normal distribution, relative bias did not exceed 9%. Using a Log-Normal FRD, we estimated prescription durations of 117, 91, 137, and 118 days for NSAIDs, warfarin, bendroflumethiazide...... two-component mixture model for the waiting time distribution (WTD). The distribution component for prevalent users estimates the forward recurrence density (FRD), which is related to the distribution of time between subsequent prescription redemptions, the inter-arrival density (IAD), for users......, and the method was applied to empirical data for four model drugs: non-steroidal anti-inflammatory drugs (NSAIDs), warfarin, bendroflumethiazide, and levothyroxine. RESULTS: Simulation studies found negligible bias when the data-generating model for the IAD coincided with the FRD used in the WTD estimation (Log-Normal...
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...
A bivariate limiting distribution of tumor latency time.
Rachev, S T; Wu, C; Yakovlev AYu
1995-06-01
The model of radiation carcinogenesis, proposed earlier by Klebanov, Rachev, and Yakovlev [8] substantiates the employment of limiting forms of the latent time distribution at high dose values. Such distributions arise within the random minima framework, the two-parameter Weibull distribution being a special case. This model, in its present form, does not allow for carcinogenesis at multiple sites. As shown in the present paper, a natural two-dimensional generalization of the model appears in the form of a Weibull-Marshall-Olkin distribution. Similarly, the study of a randomized version of the model based on the negative binomial minima scheme results in a bivariate Pareto-Marshall-Olkin distribution. In the latter case, an estimate for the rate of convergence to the limiting distribution is given.
Non-Poissonian Distribution of Tsunami Waiting Times
Geist, E. L.; Parsons, T.
2007-12-01
Analysis of the global tsunami catalog indicates that tsunami waiting times deviate from an exponential distribution one would expect from a Poisson process. Empirical density distributions of tsunami waiting times were determined using both global tsunami origin times and tsunami arrival times at a particular site with a sufficient catalog: Hilo, Hawai'i. Most sources for the tsunamis in the catalog are earthquakes; other sources include landslides and volcanogenic processes. Both datasets indicate an over-abundance of short waiting times in comparison to an exponential distribution. Two types of probability models are investigated to explain this observation. Model (1) is a universal scaling law that describes long-term clustering of sources with a gamma distribution. The shape parameter (γ) for the global tsunami distribution is similar to that of the global earthquake catalog γ=0.63-0.67 [Corral, 2004]. For the Hilo catalog, γ is slightly greater (0.75-0.82) and closer to an exponential distribution. This is explained by the fact that tsunamis from smaller triggered earthquakes or landslides are less likely to be recorded at a far-field station such as Hilo in comparison to the global catalog, which includes a greater proportion of local tsunamis. Model (2) is based on two distributions derived from Omori's law for the temporal decay of triggered sources (aftershocks). The first is the ETAS distribution derived by Saichev and Sornette [2007], which is shown to fit the distribution of observed tsunami waiting times. The second is a simpler two-parameter distribution that is the exponential distribution augmented by a linear decay in aftershocks multiplied by a time constant Ta. Examination of the sources associated with short tsunami waiting times indicate that triggered events include both earthquake and landslide tsunamis that begin in the vicinity of the primary source. Triggered seismogenic tsunamis do not necessarily originate from the same fault zone
The coronal mass ejection waiting-time distribution
Wheatland, M S
2003-01-01
The distribution of times $\\Delta t$ between coronal mass ejections (CMEs) in the Large Angle and Spectrometric Coronagraph (LASCO) CME catalog for the years 1996-2001 is examined. The distribution exhibits a power-law tail $\\propto (\\Delta t)^{\\gamma}$ with an index $\\gamma\\approx -2.36\\pm 0.11$ for large waiting times ($\\Delta t>10 {\\rm hours}$). The power-law index of the waiting-time distribution varies with the solar cycle: for the years 1996-1998 (a period of low activity), the power-law index is $\\gamma\\approx-1.86\\pm 0.14$, and for the years 1999-2001 (a period of higher activity), the index is $\\gamma\\approx-2.98\\pm 0.20$. The observed CME waiting-time distribution, and its variation with the cycle, may be understood in terms of CMEs occurring as a time-dependent Poisson process. The CME waiting-time distribution is compared with that for greater than C1 class solar flares in the Geostationary Operational Environmental Satellite (GOES) catalog for the same years. The flare and CME waiting-time distri...
A model for the distribution of aftershock waiting times
Shcherbakov, R; Turcotte, D L; Yakovlev, G
2005-01-01
In this work the distribution of inter-occurrence times between earthquakes in aftershock sequences is analyzed and a model based on a non-homogeneous Poisson (NHP) process is proposed to quantify the observed scaling. In this model the generalized Omori's law for the decay of aftershocks is used as a time-dependent rate in the NHP process. The analytically derived distribution of inter-occurrence times is applied to several major aftershock sequences in California to confirm the validity of the proposed hypothesis.
Analysis and Synthesis of Distributed Real-Time Embedded Systems
DEFF Research Database (Denmark)
Pop, Paul; Eles, Petru; Peng, Zebo
Embedded computer systems are now everywhere: from alarm clocks to PDAs, from mobile phones to cars, almost all the devices we use are controlled by embedded computers. An important class of embedded computer systems is that of hard real-time systems, which have to fulfill strict timing...... in important reductions of design costs. Analysis and Synthesis of Distributed Real-Time Embedded Systems will be of interest to advanced undergraduates, graduate students, researchers and designers involved in the field of embedded systems....
BaF2 TIME DIFFERENTIAL PERTURBED ANGULAR DISTRIBUTION SPECTROMETER
Institute of Scientific and Technical Information of China (English)
朱升云; 勾振辉; 等
1994-01-01
A BaF2 time differential perturbed angular distribution spectrometer has been established at the HI-13 tandem accelerator in CIAE.The time resolution of the spectrometer is 195ps and the nonlinearity is less than 2%.The spectrometer works very stably and no time drift is found over a period of experimental runs.This spectrometer has been successfully used in the g-factor measurement of 43Sc(19/2-,3.1232MeV).
Properties of Distributed Timed-Arc Petri Nets
DEFF Research Database (Denmark)
Nielsen, M.; Sassone, V.; Srba, J.
2001-01-01
In [12] we started a research on a distributed-timed extension of Petri nets where time parameters are associated with tokens and arcs carry constraints that qualify the age of tokens required for enabling. This formalism enables to model e.g. hardware architectures like GALS. We give a formal de...... definition of process semantics for our model and investigate several properties of local versus global timing: expressiveness, reachability and coverability....
Distributed consensus on minimum time rendezvous via cyclic alternating projection
Hu, Chunhe; Chen, Zongji
2014-01-01
In this paper, we propose a distributed algorithm to solve planar minimum time multi-vehicle rendezvous problem with non-identical velocity constraints on cyclic digraph (topology). Motivated by the cyclic alternating projection method that can compute a point's projection on the intersection of some convex sets, we transform the minimum time rendezvous problem into finding the distance between the position plane and the intersection of several second-order cones in position-time space. The d...
Consequences of mixing assumptions for time-variable travel time distributions
Velde, van der Y.; Heidbüchel, I.; Lyon, S.W.; Nyberg, L.; Rodhe, A.; Bishop, K.; Troch, P.A.
2015-01-01
The current generation of catchment travel time distribution (TTD) research, integrating nearly three decades of work since publication of Water's Journey from Rain to Stream, seeks to represent the full distribution in catchment travel times and its temporal variability. Here, we compare conceptual
Consequences of mixing assumptions for time-variable travel time distributions
Velde, van der Y.; Heidbüchel, I.; Lyon, S.W.; Nyberg, L.; Rodhe, A.; Bishop, K.; Troch, P.A.
2015-01-01
The current generation of catchment travel time distribution (TTD) research, integrating nearly three decades of work since publication of Water's Journey from Rain to Stream, seeks to represent the full distribution in catchment travel times and its temporal variability. Here, we compare
Execution time support for scientific programs on distributed memory machines
Berryman, Harry; Saltz, Joel; Scroggs, Jeffrey
1990-01-01
Optimizations are considered that are required for efficient execution of code segments that consists of loops over distributed data structures. The PARTI (Parallel Automated Runtime Toolkit at ICASE) execution time primitives are designed to carry out these optimizations and can be used to implement a wide range of scientific algorithms on distributed memory machines. These primitives allow the user to control array mappings in a way that gives an appearance of shared memory. Computations can be based on a global index set. Primitives are used to carry out gather and scatter operations on distributed arrays. Communications patterns are derived at runtime, and the appropriate send and receive messages are automatically generated.
Turkey: distribution of cities and change over time.
Dokmeci, V F
1986-01-01
Patterns of urbanization in Turkey from 1945 to 1975 are examined, with emphasis on the analysis of rank-size patterns. Attention is given to changes over time in the national rank-size distribution of cities, the growth rates of new cities, and the rank-size distribution of cities in various regions. "In general, the patterns of distribution of cities in Turkey are quite regular when compared with other developing countries. Since 1945 the city system has moved to a state more adjusted to the rank-size rule, paralleling the economic development of the country." excerpt
Towards a Notion of Distributed Time for Petri Nets
DEFF Research Database (Denmark)
Nielsen, Mogens; Sassone, Vladimiro; Srba, Jiří
2001-01-01
We set the ground for research on a timed extension of Petri nets where time parameters are associated with tokens and arcs carry constraints that qualify the age of tokens required for enabling. The novelty is that, rather than a single global clock, we use a set of unrelated clocks — possibly o...... per place — allowing a local timing as well as distributed time synchronisation. We give a formal definition of the model and investigate properties of local versus global timing, including decidability issues and notions of processes of the respective models....
Verifying Automata Specification of Distributed Probabilistic Real—Time Systems
Institute of Scientific and Technical Information of China (English)
罗铁庚; 陈火旺; 等
1998-01-01
In this paper,a qualitative model checking algorithm for verification of distributed probabilistic real-time systems(DPRS)is presented.The model of DPRS,called real-time proba bilistic process model(RPPM),is over continuous time domain.The properties of DPRS are described by using deterministic timed automata(DTA).The key part in the algorithm is to map continuous time to finite time intervals with flag variables.Compared with the existing algorithms,this algorithm uses more general delay time equivalence classes instead of the unit delay time equivalence classes restricted by event sequence,and avoids generating the equivalence classes of states only due to the passage of time.The result shows that this algorithm is cheaper.
Poverty Index With Time Varying Consumption and Income Distributions
Chattopadhyay, Amit K; Mallick, Sushanta K
2016-01-01
In a recent work (Chattopadhyay, A. K. et al, Europhys. Lett. {\\bf 91}, 58003, 2010) based on food consumption statistics, we showed how a stochastic agent based model could represent the time variation of the income distribution statistics in a developing economy, thereby defining an alternative \\enquote{poverty index} (PI) that largely agreed with poverty gap index data. This PI used two variables, the probability density function of the income statistics and a consumption deprivation (CD) function, representing the shortfall in the minimum consumption needed for survival. Since the time dependence of the CD function was introduced there through data extrapolation only and not through an endogenous time dependent series, this model left unexplained how the minimum consumption needed for survival varies with time. The present article overcomes these limitations and arrives at a new unified theoretical structure through time varying consumption and income distributions where trade is only allowed when the inc...
Poisson distributions for sharp-time fields antidote for triviality
Klauder, J R
1995-01-01
Standard lattice-space formulations of quartic self-coupled Euclidean scalar quantum fields become trivial in the continuum limit for sufficiently high space-time dimensions, and in particular the moment generating functional for space-time smeared fields becomes a Gaussian appropriate to that of a (possibly generalized) free field. For sharp-time fields this fact implies that the ground-state expectation functional also becomes Gaussian in the continuum limit. To overcome these consequences of the central limit theorem, an auxiliary, nonclassical potential is appended to the original lattice form of the model and parameters are tuned so that a generalized Poisson field distribution emerges in the continuum limit for the ground-state probability distribution. As a consequence, the sharp-time expectation functional is infinitely divisible, but the Hamiltonian operator is such, in the general case, that the generating functional for the space-time smeared field is not infinitely divisible in Minkowski space. Th...
Visualization of EEG using time-frequency distributions.
Stiber, B Z; Sato, S
1997-12-01
The EEG is a time-varying or nonstationary signal. Frequency and amplitude are two of its significant characteristics, and are valuable clues to different states of brain activity. Detection of these temporal features is important in understanding EEGs. Commonly, spectrograms and AR models are used for EEG analysis. However, their accuracy is limited by their inherent assumption of stationarity and their trade-off between time and frequency resolution. We investigate EEG signal processing using existing compound kernel time-frequency distributions (TFDs). By providing a joint distribution of signal intensity at any frequency along time, TFDs preserve details of the temporal structure of the EEG waveform, and can extract its time-varying frequency and amplitude features. We expect that this will have significant implications for EEG analysis and medical diagnosis.
Directory of Open Access Journals (Sweden)
Marco Basile
2016-09-01
Full Text Available Environmental heterogeneity affects not only the distribution of a species but also its local abundance. High heterogeneity due to habitat alteration and fragmentation can influence the realized niche of a species, lowering habitat suitability as well as reducing local abundance. We investigate whether a relationship exists between habitat suitability and abundance and whether both are affected by fragmentation. Our aim was to assess the predictive power of such a relationship to derive advice for environmental management. As a model species we used a forest specialist, the short-toed treecreeper (Family: Certhiidae; Certhia brachydactyla Brehm, 1820, and sampled it in central Italy. Species distribution was modelled as a function of forest structure, productivity and fragmentation, while abundance was directly estimated in two central Italian forest stands. Different algorithms were implemented to model species distribution, employing 170 occurrence points provided mostly by the MITO2000 database: an artificial neural network, classification tree analysis, flexible discriminant analysis, generalized boosting models, generalized linear models, multivariate additive regression splines, maximum entropy and random forests. Abundance was estimated also considering detectability, through N-mixture models. Differences between forest stands in both abundance and habitat suitability were assessed as well as the existence of a relationship. Simpler algorithms resulted in higher goodness of fit than complex ones. Fragmentation was highly influential in determining potential distribution. Local abundance and habitat suitability differed significantly between the two forest stands, which were also significantly different in the degree of fragmentation. Regression showed that suitability has a weak significant effect in explaining increasing value of abundance. In particular, local abundances varied both at low and high suitability values. The study lends
"Universal" Distribution of Inter-Earthquake Times Explained
Saichev, A
2006-01-01
We propose a simple theory for the ``universal'' scaling law previously reported for the distributions of waiting times between earthquakes. It is based on a largely used benchmark model of seismicity, which just assumes no difference in the physics of foreshocks, mainshocks and aftershocks. Our theoretical calculations provide good fits to the data and show that universality is only approximate. We conclude that the distributions of inter-event times do not reveal more information than what is already known from the Gutenberg-Richter and the Omori power laws. Our results reinforces the view that triggering of earthquakes by other earthquakes is a key physical mechanism to understand seismicity.
Factors Influencing Dwell Fatigue Cracking in Notches of Powder Metallurgy Superalloys
Gabb, T. P.; Telesman, J.; Ghosn, L.; Garg, A.; Gayda, J.
2011-01-01
The influences of heat treatment and cyclic dwells on the notch fatigue resistance of powder metallurgy disk superalloys were investigated for low solvus high refractory (LSHR) and ME3 disk alloys. Disks were processed to produce material conditions with varied microstructures and associated mechanical properties. Notched specimens were first subjected to baseline dwell fatigue cycles having a dwell at maximum load, as well as tensile, stress relaxation, creep rupture, and dwell fatigue crack growth tests at 704 C. Several material heat treatments displayed a bimodal distribution of fatigue life with the lives varying by two orders-of-magnitude, while others had more consistent fatigue lives. This response was compared to other mechanical properties, in search of correlations. The wide scatter in baseline dwell fatigue life was observed only for material conditions resistant to stress relaxation. For selected materials and conditions, additional tests were then performed with the dwells shifted in part or in total to minimum tensile load. The tests performed with dwells at minimum load exhibited lower fatigue lives than max dwell tests, and also exhibited early crack initiation and a substantial increase in the number of initiation sites. These results could be explained in part by modeling evolution of peak stresses in the notch with continued dwell fatigue cycling. Fatigue-environment interactions were determined to limit life for the fatigue cycles with dwells.
Time Synchronization and Distribution Mechanisms for Space Networks
Woo, Simon S.; Gao, Jay L.; Clare, Loren P.; Mills, David L.
2011-01-01
This work discusses research on the problems of synchronizing and distributing time information between spacecraft based on the Network Time Protocol (NTP), where NTP is a standard time synchronization protocol widely used in the terrestrial network. The Proximity-1 Space Link Interleaved Time Synchronization (PITS) Protocol was designed and developed for synchronizing spacecraft that are in proximity where proximity is less than 100,000 km distant. A particular application is synchronization between a Mars orbiter and rover. Lunar scenarios as well as outer-planet deep space mother-ship-probe missions may also apply. Spacecraft with more accurate time information functions as a time-server, and the other spacecraft functions as a time-client. PITS can be easily integrated and adaptable to the CCSDS Proximity-1 Space Link Protocol with minor modifications. In particular, PITS can take advantage of the timestamping strategy that underlying link layer functionality provides for accurate time offset calculation. The PITS algorithm achieves time synchronization with eight consecutive space network time packet exchanges between two spacecraft. PITS can detect and avoid possible errors from receiving duplicate and out-of-order packets by comparing with the current state variables and timestamps. Further, PITS is able to detect error events and autonomously recover from unexpected events that can possibly occur during the time synchronization and distribution process. This capability achieves an additional level of protocol protection on top of CRC or Error Correction Codes. PITS is a lightweight and efficient protocol, eliminating the needs for explicit frame sequence number and long buffer storage. The PITS protocol is capable of providing time synchronization and distribution services for a more general domain where multiple entities need to achieve time synchronization using a single point-to-point link.
Temporal Architecture: Poetic Dwelling in Japanese buildings
Directory of Open Access Journals (Sweden)
Michael Lazarin
2014-07-01
Full Text Available Heidegger’s thinking about poetic dwelling and Derrida’s impressions of Freudian estrangement are employed to provide a constitutional analysis of the experience of Japanese architecture, in particular, the Japanese vestibule (genkan. This analysis is supplemented by writings by Japanese architects and poets. The principal elements of Japanese architecture are: (1 ma, and (2 en. Ma is usually translated as ‘interval’ because, like the English word, it applies to both space and time. However, in Japanese thinking, it is not so much an either/or, but rather a both/and. In other words, Japanese architecture emphasises the temporal aspect of dwelling in a way that Western architectural thinking usually does not. En means ‘joint, edge, the in-between’ as an ambiguous, often asymmetrical spanning of interior and exterior, rather than a demarcation of these regions. Both elements are aimed at producing an experience of temporality and transiency.
First-Passage-Time Distribution for Variable-Diffusion Processes
Barney, Liberty; Gunaratne, Gemunu H.
2017-05-01
First-passage-time distribution, which presents the likelihood of a stock reaching a pre-specified price at a given time, is useful in establishing the value of financial instruments and in designing trading strategies. First-passage-time distribution for Wiener processes has a single peak, while that for stocks exhibits a notable second peak within a trading day. This feature has only been discussed sporadically—often dismissed as due to insufficient/incorrect data or circumvented by conversion to tick time—and to the best of our knowledge has not been explained in terms of the underlying stochastic process. It was shown previously that intra-day variations in the market can be modeled by a stochastic process containing two variable-diffusion processes (Hua et al. in, Physica A 419:221-233, 2015). We show here that the first-passage-time distribution of this two-stage variable-diffusion model does exhibit a behavior similar to the empirical observation. In addition, we find that an extended model incorporating overnight price fluctuations exhibits intra- and inter-day behavior similar to those of empirical first-passage-time distributions.
MicROS-drt: supporting real-time and scalable data distribution in distributed robotic systems.
Ding, Bo; Wang, Huaimin; Fan, Zedong; Zhang, Pengfei; Liu, Hui
A primary requirement in distributed robotic software systems is the dissemination of data to all interested collaborative entities in a timely and scalable manner. However, providing such a service in a highly dynamic and resource-limited robotic environment is a challenging task, and existing robot software infrastructure has limitations in this aspect. This paper presents a novel robot software infrastructure, micROS-drt, which supports real-time and scalable data distribution. The solution is based on a loosely coupled data publish-subscribe model with the ability to support various time-related constraints. And to realize this model, a mature data distribution standard, the data distribution service for real-time systems (DDS), is adopted as the foundation of the transport layer of this software infrastructure. By elaborately adapting and encapsulating the capability of the underlying DDS middleware, micROS-drt can meet the requirement of real-time and scalable data distribution in distributed robotic systems. Evaluation results in terms of scalability, latency jitter and transport priority as well as the experiment on real robots validate the effectiveness of this work.
Power Quality Analysis Using Bilinear Time-Frequency Distributions
Directory of Open Access Journals (Sweden)
Sha'ameri AhmadZuri
2010-01-01
Full Text Available Abstract Bilinear time-frequency distributions (TFDs are powerful techniques that offer good time and frequency resolution of time-frequency representation (TFR. It is very appropriate to analyze power quality signals which consist of nonstationary and multi-frequency components. However, the TFDs suffer from interference because of cross-terms. Many TFDs have been implemented, and there is no fixed window or kernel that can remove the cross-terms for all types of signals. In this paper, the bilinear TFDs are implemented to analyze power quality signals such as smooth-windowed Wigner-Ville distribution (SWWVD, Choi-Williams distribution (CWD, B-distribution (BD, and modified B-distribution (MBD. The power quality signals focused are swell, sag, interruption, harmonic, interharmonic, and transient based on IEEE Std, 1159-1995. A set of performance measures is defined and used to compare the TFRs. It shows that SWWVD presents the best performance and is selected for power quality signal analysis. Thus, an adaptive optimal kernel SWWVD is designed to determine the separable kernel automatically from the input signal.
Distributed LQR control for discrete-time homogeneous systems
Wang, Wei; Zhang, Fangfang; Han, Chunyan
2016-11-01
This paper investigates the distributed linear quadratic regulation (LQR) controller design method for discrete-time homogeneous scalar systems. Based on the optimal centralised control theory, the existence condition for distributed optimal controller is firstly proposed. It shows that the globally optimal distributed controller is dependent on the structure of the penalty matrix. Such results can be used in consensus problems and used to find under which communication topology (may not be an all-to-all form) the optimal distributed controller exists. When the proposed condition cannot hold, a suboptimal design method with the aid of the decomposition of discrete algebraic Riccati equations and robustness of local controllers is proposed. The computation complexity and communication load for each subsystem are only dependent on the number of its neighbours.
Real Time Scheduling Services for Distributed RT-CORBA Applications
Directory of Open Access Journals (Sweden)
Bineta Tresa Mathew
2012-12-01
Full Text Available Distributed computing environment is flexible to control in complex embedded systems and their software components gain complexity when these systems are equipped with many microcontrollers and software object which covers diverse platforms, this system is called as DRE system. These DRE systems need new inter-object communication solution thus QoS-enabled middleware services and mechanisms have begun to emerge. Real-time application domain benefit from flexible and open distributed architectures, such as those defined by the CORBA specification. CORBA is well-suited to conventional request/response applications, but not suited to real-time applications due to the lack of QoS features and performance optimizations. The paper shows the design and implementation of the high performance scheduling technique for the real time applications domain with CORBA systems. Four different algorithms are compared by using attributes of real time tasks constraints based on CORBA specification such as RMS, MLF, MUF and EDF.
Spatially distributed characterization of soil-moisture dynamics using travel-time distributions
Heße, Falk; Zink, Matthias; Kumar, Rohini; Samaniego, Luis; Attinger, Sabine
2017-01-01
Travel-time distributions are a comprehensive tool for the characterization of hydrological system dynamics. Unlike the streamflow hydrograph, they describe the movement and storage of water within and throughout the hydrological system. Until recently, studies using such travel-time distributions have generally either been applied to lumped models or to real-world catchments using available time series, e.g., stable isotopes. Whereas the former are limited in their realism and lack information on the spatial arrangements of the relevant quantities, the latter are limited in their use of available data sets. In our study, we employ the spatially distributed mesoscale Hydrological Model (mHM) and apply it to a catchment in central Germany. Being able to draw on multiple large data sets for calibration and verification, we generate a large array of spatially distributed states and fluxes. These hydrological outputs are then used to compute the travel-time distributions for every grid cell in the modeling domain. A statistical analysis indicates the general soundness of the upscaling scheme employed in mHM and reveals precipitation, saturated soil moisture and potential evapotranspiration as important predictors for explaining the spatial heterogeneity of mean travel times. In addition, we demonstrate and discuss the high information content of mean travel times for characterization of internal hydrological processes.
Analysis and Optimization of Distributed Real-Time Embedded Systems
DEFF Research Database (Denmark)
Pop, Paul; Eles, Petru; Peng, Zebo
2006-01-01
An increasing number of real-time applications are today implemented using distributed heterogeneous architectures composed of interconnected networks of processors. The systems are heterogeneous not only in terms of hardware and software components, but also in terms of communication protocols...
GLOBAL STABILITY IN HOPFIELD NEURAL NETWORKS WITH DISTRIBUTED TIME DELAYS
Institute of Scientific and Technical Information of China (English)
Zhang Jiye; Wu Pingbo; Dai Huanyun
2001-01-01
In this paper, without assuming the boundedness, monotonicity and differentiability of the activation functions, the conditions ensuring existence, uniqueness, and global asymptotical stability of the equilibrium point of Hopfield neural network models with distributed time delays are studied. Using M-matrix theory and constructing proper Liapunov functionals, the sufficient conditions for global asymptotic stability are obtained.
A distributed Real-Time Java system based on CSP
Hilderink, G.H.; Bakkers, André; Broenink, Johannes F.
2000-01-01
CSP is a fundamental concept for developing software for distributed real time systems. The CSP paradigm constitutes a natural addition to object orientation and offers higher order multithreading constructs. The CSP channel concept that has been implemented in Java deals with single- and
Residence Time Distributions in a Cold, Confined Swirl Flow
DEFF Research Database (Denmark)
Lans, Robert Pieter Van Der; Glarborg, Peter; Dam-Johansen, Kim;
1997-01-01
Residence time distributions (RTD) in a confined, cold swirling flow have been measured with a fast-response probe and helium as a tracer. The test-rig represented a scaled down version of a burner. The effect of variation of flow velocities and swirl angle on the flow pattern in the near-burner ...
Near-Optimal Sublinear Time Bounds for Distributed Random Walks
Sarma, Atish Das; Pandurangan, Gopal; Tetali, Prasad
2009-01-01
We focus on the problem of performing random walks efficiently in a distributed network. Given bandwidth constraints, the goal is to minimize the number of rounds required to obtain a random walk sample on an undirected network. Despite the widespread use of random walks in distributed computing, most algorithms that compute a random walk sample of length $\\ell$ naively, i.e., in $O(\\ell)$ rounds. Recently, the first sublinear time distributed algorithm was presented that ran in $\\tilde{O}(\\ell^{2/3}D^{1/3})$ rounds {$\\tilde{O}$ hides polylog factors in the number of nodes in the network} where $D$ is the diameter of the network [Das Sarma et al. PODC 2009]. This work further conjectured that a running time of $\\tilde{O}(\\sqrt{\\ell D})$ is possible and that this is essentially optimal. In this paper, we resolve these conjectures by showing almost tight bounds on distributed random walks. We present a distributed algorithm that performs a random walk of length $\\ell$ in $\\tilde{O}(\\sqrt{\\ell D})$ rounds, where...
Real-time modeling and simulation of distribution feeder and distributed resources
Singh, Pawan
The analysis of the electrical system dates back to the days when analog network analyzers were used. With the advent of digital computers, many programs were written for power-flow and short circuit analysis for the improvement of the electrical system. Real-time computer simulations can answer many what-if scenarios in the existing or the proposed power system. In this thesis, the standard IEEE 13-Node distribution feeder is developed and validated on a real-time platform OPAL-RT. The concept and the challenges of the real-time simulation are studied and addressed. Distributed energy resources include some of the commonly used distributed generation and storage devices like diesel engine, solar photovoltaic array, and battery storage system are modeled and simulated on a real-time platform. A microgrid encompasses a portion of an electric power distribution which is located downstream of the distribution substation. Normally, the microgrid operates in paralleled mode with the grid; however, scheduled or forced isolation can take place. In such conditions, the microgrid must have the ability to operate stably and autonomously. The microgrid can operate in grid connected and islanded mode, both the operating modes are studied in the last chapter. Towards the end, a simple microgrid controller modeled and simulated on the real-time platform is developed for energy management and protection for the microgrid.
Distributed, Embedded and Real-time Java Systems
Wellings, Andy
2012-01-01
Research on real-time Java technology has been prolific over the past decade, leading to a large number of corresponding hardware and software solutions, and frameworks for distributed and embedded real-time Java systems. This book is aimed primarily at researchers in real-time embedded systems, particularly those who wish to understand the current state of the art in using Java in this domain. Much of the work in real-time distributed, embedded and real-time Java has focused on the Real-time Specification for Java (RTSJ) as the underlying base technology, and consequently many of the Chapters in this book address issues with, or solve problems using, this framework. Describes innovative techniques in: scheduling, memory management, quality of service and communication systems supporting real-time Java applications; Includes coverage of multiprocessor embedded systems and parallel programming; Discusses state-of-the-art resource management for embedded systems, including Java’s real-time garbage collect...
Dose-time-response modeling using negative binomial distribution.
Roy, Munmun; Choudhury, Kanak; Islam, M M; Matin, M A
2013-01-01
People exposed to certain diseases are required to be treated with a safe and effective dose level of a drug. In epidemiological studies to find out an effective dose level, different dose levels are applied to the exposed and a certain number of cures is observed. Negative binomial distribution is considered to fit overdispersed Poisson count data. This study investigates the time effect on the response at different time points as well as at different dose levels. The point estimation and confidence bands for ED(100p)(t) and LT(100p)(d) are formulated in closed form for the proposed dose-time-response model with the negative binomial distribution. Numerical illustrations are carried out in order to check the performance level of the proposed model.
Distributed Load Shedding over Directed Communication Networks with Time Delays
Energy Technology Data Exchange (ETDEWEB)
Yang, Tao; Wu, Di
2016-07-25
When generation is insufficient to support all loads under emergencies, effective and efficient load shedding needs to be deployed in order to maintain the supply-demand balance. This paper presents a distributed load shedding algorithm, which makes efficient decision based on the discovered global information. In the global information discovery process, each load only communicates with its neighboring load via directed communication links possibly with arbitrarily large but bounded time varying communication delays. We propose a novel distributed information discovery algorithm based on ratio consensus. Simulation results are used to validate the proposed method.
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 \
A distributed scheduling algorithm for heterogeneous real-time systems
Zeineldine, Osman; El-Toweissy, Mohamed; Mukkamala, Ravi
1991-01-01
Much of the previous work on load balancing and scheduling in distributed environments was concerned with homogeneous systems and homogeneous loads. Several of the results indicated that random policies are as effective as other more complex load allocation policies. The effects of heterogeneity on scheduling algorithms for hard real time systems is examined. A distributed scheduler specifically to handle heterogeneities in both nodes and node traffic is proposed. The performance of the algorithm is measured in terms of the percentage of jobs discarded. While a random task allocation is very sensitive to heterogeneities, the algorithm is shown to be robust to such non-uniformities in system components and load.
Temperature Distribution and Heat Saturating Time of Regenerative Heat Transfer
Institute of Scientific and Technical Information of China (English)
Li JIA; Ying MAO; Lixin YANG
2006-01-01
In this paper, heat transfer of the ceramic honeycomb regenerator was numerically simulated based on the computational fluid dynamics numerical analysis software CFX5. The longitudinal temperature distribution of regenerator and gas were obtained. The variation of temperature with time was discussed. In addition, the effects of some parameters such as switching time, gas temperature at the inlet of regenerator, height of regenerator and specific heat of the regenerative materials on heat saturating time were discussed. It provided primarily theoretic basis for further study of regenerative heat transfer mechanism.
Time series power flow analysis for distribution connected PV generation.
Energy Technology Data Exchange (ETDEWEB)
Broderick, Robert Joseph; Quiroz, Jimmy Edward; Ellis, Abraham; Reno, Matthew J.; Smith, Jeff; Dugan, Roger
2013-01-01
Distributed photovoltaic (PV) projects must go through an interconnection study process before connecting to the distribution grid. These studies are intended to identify the likely impacts and mitigation alternatives. In the majority of the cases, system impacts can be ruled out or mitigation can be identified without an involved study, through a screening process or a simple supplemental review study. For some proposed projects, expensive and time-consuming interconnection studies are required. The challenges to performing the studies are twofold. First, every study scenario is potentially unique, as the studies are often highly specific to the amount of PV generation capacity that varies greatly from feeder to feeder and is often unevenly distributed along the same feeder. This can cause location-specific impacts and mitigations. The second challenge is the inherent variability in PV power output which can interact with feeder operation in complex ways, by affecting the operation of voltage regulation and protection devices. The typical simulation tools and methods in use today for distribution system planning are often not adequate to accurately assess these potential impacts. This report demonstrates how quasi-static time series (QSTS) simulation and high time-resolution data can be used to assess the potential impacts in a more comprehensive manner. The QSTS simulations are applied to a set of sample feeders with high PV deployment to illustrate the usefulness of the approach. The report describes methods that can help determine how PV affects distribution system operations. The simulation results are focused on enhancing the understanding of the underlying technical issues. The examples also highlight the steps needed to perform QSTS simulation and describe the data needed to drive the simulations. The goal of this report is to make the methodology of time series power flow analysis readily accessible to utilities and others responsible for evaluating
Optimization of Time-Partitions for Mixed-Criticality Real-Time Distributed Embedded Systems
DEFF Research Database (Denmark)
Tamas-Selicean, Domitian; Pop, Paul
2011-01-01
In this paper we are interested in mixed-criticality embedded real-time applications mapped on distributed heterogeneous architectures. The architecture provides both spatial and temporal partitioning, thus enforcing enough separation for the critical applications. With temporal partitioning, each...
Time-evolving distribution of time lags between commercial airline disasters
Ausloos, M
2005-01-01
We have studied the time lags between commercial line airplane disasters and their occurrence frequency till 2002, as obtained from a freely available website. We show that the time lags seem to be well described by Poisson random events, where the average events rate is itself a function of time, i.e. time-dependent Poisson events. This is likely due to the unsteady growth of the industry. The time lag distribution is compared with a truncated Tsallis distribution, thereby showing that the ''phenomenon'' has similarities with a Brownian particle with time dependent mass. We distinguish between ''other causes'' (or natural causes) and ''terrorism acts", the latter amounts to about 5 percents, but we find no drastic difference nor impact due to the latter on the overall distribution.
Real-time dynamic imaging of virus distribution in vivo.
Directory of Open Access Journals (Sweden)
Sean E Hofherr
Full Text Available The distribution of viruses and gene therapy vectors is difficult to assess in a living organism. For instance, trafficking in murine models can usually only be assessed after sacrificing the animal for tissue sectioning or extraction. These assays are laborious requiring whole animal sectioning to ascertain tissue localization. They also obviate the ability to perform longitudinal or kinetic studies in one animal. To track viruses after systemic infection, we have labeled adenoviruses with a near-infrared (NIR fluorophore and imaged these after intravenous injection in mice. Imaging was able to track and quantitate virus particles entering the jugular vein simultaneous with injection, appearing in the heart within 500 milliseconds, distributing in the bloodstream and throughout the animal within 7 seconds, and that the bulk of virus distribution was essentially complete within 3 minutes. These data provide the first in vivo real-time tracking of the rapid initial events of systemic virus infection.
Implementation of a Wireless Time Distribution Testbed Protected with Quantum Key Distribution
Energy Technology Data Exchange (ETDEWEB)
Bonior, Jason D [ORNL; Evans, Philip G [ORNL; Sheets, Gregory S [ORNL; Jones, John P [ORNL; Flynn, Toby H [ORNL; O' Neil, Lori Ross [Pacific Northwest National Laboratory (PNNL); Hutton, William [Pacific Northwest National Laboratory (PNNL); Pratt, Richard [Pacific Northwest National Laboratory (PNNL); Carroll, Thomas E. [Pacific Northwest National Laboratory (PNNL)
2017-01-01
Secure time transfer is critical for many timesensitive applications. the Global Positioning System (GPS) which is often used for this purpose has been shown to be susceptible to spoofing attacks. Quantum Key Distribution offers a way to securely generate encryption keys at two locations. Through careful use of this information it is possible to create a system that is more resistant to spoofing attacks. In this paper we describe our work to create a testbed which utilizes QKD and traditional RF links. This testbed will be used for the development of more secure and spoofing resistant time distribution protocols.
Lightweight distributed computing for intraoperative real-time image guidance
Suwelack, Stefan; Katic, Darko; Wagner, Simon; Spengler, Patrick; Bodenstedt, Sebastian; Röhl, Sebastian; Dillmann, Rüdiger; Speidel, Stefanie
2012-02-01
In order to provide real-time intraoperative guidance, computer assisted surgery (CAS) systems often rely on computationally expensive algorithms. The real-time constraint is especially challenging if several components such as intraoperative image processing, soft tissue registration or context aware visualization are combined in a single system. In this paper, we present a lightweight approach to distribute the workload over several workstations based on the OpenIGTLink protocol. We use XML-based message passing for remote procedure calls and native types for transferring data such as images, meshes or point coordinates. Two different, but typical scenarios are considered in order to evaluate the performance of the new system. First, we analyze a real-time soft tissue registration algorithm based on a finite element (FE) model. Here, we use the proposed approach to distribute the computational workload between a primary workstation that handles sensor data processing and visualization and a dedicated workstation that runs the real-time FE algorithm. We show that the additional overhead that is introduced by the technique is small compared to the total execution time. Furthermore, the approach is used to speed up a context aware augmented reality based navigation system for dental implant surgery. In this scenario, the additional delay for running the computationally expensive reasoning server on a separate workstation is less than a millisecond. The results show that the presented approach is a promising strategy to speed up real-time CAS systems.
A time reference distribution concept for a time division communication network
Stover, H. A.
1973-01-01
Starting with an assumed ideal network having perfect clocks at every node and known fixed transmission delays between nodes, the effects of adding tolerances to both transmission delays and nodal clocks is described. The advantages of controlling tolerances on time rather than frequency are discussed. Then a concept is presented for maintaining these tolerances on time throughout the network. This concept, called time reference distribution, is a systematic technique for distributing time reference to all nodes of the network. It is reliable, survivable and possesses many other desirable characteristics. Some of its features such as an excellent self monitoring capability will be pointed out. Some preliminary estimates of the accuracy that might be expected are developed and there is a brief discussion of the impact upon communication system costs. Time reference distribution is a concept that appears very attractive. It has not had experimental evaluation and has not yet been endorsed for use in any communication network.
Poverty Index With Time Varying Consumption and Income Distributions
2016-01-01
In a recent work (Chattopadhyay, A. K. et al, Europhys. Lett. {\\bf 91}, 58003, 2010) based on food consumption statistics, we showed how a stochastic agent based model could represent the time variation of the income distribution statistics in a developing economy, thereby defining an alternative \\enquote{poverty index} (PI) that largely agreed with poverty gap index data. This PI used two variables, the probability density function of the income statistics and a consumption deprivation (CD) ...
DEFF Research Database (Denmark)
Wang, Qi
and DR resources, and upwardly trading in the TL real-time market, resulting in a proactive manner. The DL aggregator (DA) is dened to manage these small-scale and dispersed DGs and DRs. A methodology is proposed in this thesis for a proactive DISCO (PDISCO) to strategically trade with DAs......-level model is proposed to elaborate the interactions between the PDISCO's bids/offers and the TL market's outcomes. The PDISCO's trading performance features in a bidirectional transaction. In this thesis, replacing the lower-level problems with the primal-dual approach, each proposed bi-level model......Distributed energy resources (DERs), such as distributed generation (DG) and demand response (DR), have been recognized worldwide as valuable resources. High integration of DG and DR in the distribution network inspires a potential deregulated environment for the distribution company (DISCO...
On enhanced time-varying distributed H systems
Directory of Open Access Journals (Sweden)
Sergey Verlan
2002-11-01
Full Text Available An enhanced time-varying distributed H system (ETVDH system is a slightly different definition of the time-varying distributed H system (TVDH system [9] and it was proposed by M. Margenstern and Yu. Rogozhin in [4] under the name of "extended time-varying distributed H system''. The main difference is that the components of the ETVDH system are H systems and therefore splicing rules may be applied more than once as it is done in TVDH systems. This leads to difficulties in investigating the behavior of such systems because they have a higher level of parallelism. It is proved that ETVDH systems of degree 2 (i.e. with 2 components generate all recursively enumerable languages in a sequential way [7] and that ETVDH systems of degree 4 generate all recursively enumerable languages in a "parallel'' way, modelling a formal type-0 grammar [11]. In this paper we improve the last result and we present an ETVDH system of degree 3 which generates all recursively enumerable languages modelling type-0 formal grammars. The problem of the existence of ETVDH systems of degree 2 which generate all recursively enumerable languages in a "parallel'' way is left open.
High-resolution time-frequency distributions for fall detection
Amin, Moeness G.; Zhang, Yimin D.; Boashash, Boualem
2015-05-01
In this paper, we examine the role of high-resolution time-frequency distributions (TFDs) of radar micro-Doppler signatures for fall detection. The work supports the recent and rising interest in using emerging radar technology for elderly care and assisted living. Spectrograms have been the de facto joint-variable signal representation, depicting the signal power in both time and frequency. Although there have been major advances in designing quadratic TFDs which are superior to spectrograms in terms of detailing the local signal behavior, the contributions of these distributions in the area of human motion classifications and their offerings in enhanced feature extractions have not yet been properly evaluated. The main purpose of this paper is to show the effect of using high-resolution TFD kernels, in lieu of spectrogram, on fall detection. We focus on the extended modified B-distribution (EMBD) and exploit the level of details it provides as compared with the coarse and smoothed time-frequency signatures offered by spectrograms.
Directory of Open Access Journals (Sweden)
Harold L. Merriman
2011-01-01
Full Text Available Though popular, there is little agreement on what whole-body vibration (WBV parameters will optimize performance. This study aimed to clarify the effects of age, sex, hertz and time on four physical function indicators in community-dwelling older adults (=32. Participants were exposed to 2 min WBV per session at either 2 Hz or 26 Hz and outcome measures were recorded at 2, 20 and 40 min post-WBV. Timed get up-and-go and chair sit-and-reach performances improved post-WBV for both sexes, were significantly different between 2 Hz and 26 Hz treatments (≤0.05 and showed statistically significant interactions between age and gender (≤0.01. Counter movement jump and timed one-legged stance performances showed a similar but non-significant response to 2 Hz and 26 Hz treatments, though male subjects showed a distinct trended response. Age and gender should be statistically controlled and both 2 Hz and 26 Hz exert a treatment effect.
Time and temporality: linguistic distribution in human life-games
DEFF Research Database (Denmark)
Cowley, Stephen
2014-01-01
While clock-time can be used to clarify facts, all living systems construct their own temporalities. Having illustrated the claim for foxtail grasses, it is argued that, with motility and brains, organisms came to use temporalities that build flexibility into behavior. With the rise of human...... culture, individuals developed a knack of using linguistic distribution to link metabolism with collective ways of assessing and managing experience. Of human temporal management, the best known case is the mental time travel enabled by, among other functions, autobiographical memory. One contribution...
Time-Mean Helicity Distribution in Turbulent Swirling Jets
Directory of Open Access Journals (Sweden)
V. Tesař
2005-01-01
Full Text Available Helicity offers an alternative approach to investigations of the structure of turbulent flows. Knowledge of the spatial distribution of the time-mean component of helicity is the starting point. Yet very little is known even about basic cases in which Helicity plays important role, such as the case of a swirling jet. This is the subject of the present investigations, based mainly on numerical flowfield computations. The region of significantly large time-mean helicity density is found only in a rather small region reaching to several nozzle diameters downstream from the exit. The most important result is the similarity of the helicity density profiles.
Real Time Scheduling Services for Distributed RT-CORBA Applications
Directory of Open Access Journals (Sweden)
Bineta Tresa Mathew
2012-12-01
Full Text Available Distributed computing environment is flexible to control in complex embedded systems and their software components gain complexity when these systems are equipped with many microcontrollers and software object which covers diverse platforms, this system is called as DRE system. These DRE systems need new inter-object communication solution thus QoS-enabled middleware services and mechanisms have begun to emerge. Real-time application domain benefit from flexible and open distributed architectures, such as those defined by the CORBA specification. CORBA is well-suited to conventional request/response applications, but not suited to real-time applications due to the lack of QoS features and performance optimizations. The paper shows the design and implementation of the high performance scheduling technique for the real time applications domain with CORBA systems. Four different algorithms are compared by using attributes of real time tasks constraints based on CORBA specification such as RMS, MLF, MUF and EDF. The experimental outcome demonstrates the better performance of MLF by analyzing the time taken for the execution of several numbers of tasks and further it can be compared with the combination of RMS and MLF to reach the best performance strategy.
A probability distribution approach to synthetic turbulence time series
Sinhuber, Michael; Bodenschatz, Eberhard; Wilczek, Michael
2016-11-01
The statistical features of turbulence can be described in terms of multi-point probability density functions (PDFs). The complexity of these statistical objects increases rapidly with the number of points. This raises the question of how much information has to be incorporated into statistical models of turbulence to capture essential features such as inertial-range scaling and intermittency. Using high Reynolds number hot-wire data obtained at the Variable Density Turbulence Tunnel at the Max Planck Institute for Dynamics and Self-Organization, we establish a PDF-based approach on generating synthetic time series that reproduce those features. To do this, we measure three-point conditional PDFs from the experimental data and use an adaption-rejection method to draw random velocities from this distribution to produce synthetic time series. Analyzing these synthetic time series, we find that time series based on even low-dimensional conditional PDFs already capture some essential features of real turbulent flows.
Space--times with distribution valued curvature tensors
Energy Technology Data Exchange (ETDEWEB)
Taub, A.H.
1980-06-01
A space--time in which in an admissible coordinate system the metric tensor is continuous but has a finite jump in its first and second derivatives across a submanifold will have a curvature tensor containing a Dirac delta function. The support of this distribution may be of three, two, or one dimension or may even consist of a single event. Lichnerowicz's formalism for dealing with such tensors is modified so as to obtain a formalism in which the Bianchi identities are satisfied in the sense of distributions. The resulting formalism is then applied to the discussion of the Einstein field equations for problems in which the source of the gravitational field is given by a distribution valued stress-energy tensor. Gravitational shocks are also discussed and their theory is compared with that of high-frequency gravitational waves given by Y. Choquet-Bruhat. By considering a class of line sources as obtainable from cylindrical shells by a limiting process, as was proposed by Israel, one may use the distribution formalism developed for hypersurfaces to treat line sources. The line source model proposed by Israel to represent the Kerr metric in the neighborhood of its singular disk is shown to lead to a gravitational mass and angular momentum inconsistent with those of the latter metric. It is proposed to remove this difficulty by changing the assumptions made by Israel concerning the nature of the space--time inside the cylindrical shell which is the support of the distribution in the curvature tensor. The details of the effect of this change are not given in this paper.
The spectrum of worry in the community-dwelling elderly.
LENUS (Irish Health Repository)
Golden, Jeannette
2011-11-01
In this study, we examine the prevalence and distribution of worry, its content, and its associations with quality of life and depression, based on a large sample of community-dwelling elderly. We will attempt to distinguish between pathological and non-pathological worry based on these associations.
Time-optimal control of infinite order distributed parabolic systems involving time lags
Directory of Open Access Journals (Sweden)
G.M. Bahaa
2014-06-01
Full Text Available A time-optimal control problem for linear infinite order distributed parabolic systems involving constant time lags appear both in the state equation and in the boundary condition is presented. Some particular properties of the optimal control are discussed.
Embedding and Distributing Constant Time Delay in Circle Time and Transitions.
Wolery, Mark; Anthony, Leslie; Caldwell, Nicola K.; Snyder, Erin D.; Morgante, James D.
2002-01-01
This study evaluated embedding and distributing constant time delay instructional trials into circle time and transitions between activities in a summer camp program. Three boys (ages 5-8) with disabilities or behavior problems participated. Results indicated the children acquired the behaviors they were taught and generalized the learned…
Distribution of relaxation times of relaxors: comparison with dipolar glasses
Energy Technology Data Exchange (ETDEWEB)
Banys, Juras; Grigalaitis, Robertas; Mikonis, Andrejus; Keburis, Povilas [Faculty of Physics, Vilnius University, Sauletekio 9, 10222 Vilnius (Lithuania); Macutkevic, Jan [Semiconductor Physics Institute, A. Gostauto 11, 01108 Vilnius (Lithuania)
2009-12-15
In the present publication we report the results of dielectric spectroscopy investigations of two classes of materials - relaxor and dipolar glasses. As model relaxor was chosen (Pb{sub 1-x}La{sub x})(Zr{sub y}Ti{sub 1-y})O{sub 3} (PLZT 100(x/y/1-y)). The real distribution function of the relaxation times f ({tau}) of the relaxor ferroelectric ceramics PLZT 8/65/35 and 9.5/65/35 was calculated from the dielectric measurements results in the wide frequency range (10{sup 1}-10{sup 12} Hz). Below the Burns temperature T{sub B} {approx_equal} 620 K, when the clusters begin to appear on cooling, the distribution function of the relaxation times is symmetrically shaped. On cooling the dispersion and loss spectra strongly broaden and slow down, the f ({tau}) function becomes asymmetrically shaped and the second maximum appears. The width of the f ({tau}) function was calculated at different temperatures. The longest relaxation times diverge according to the Vogel-Fulcher law with the freezing temperature 299 K and 252 K for the 8/65/35 and 9.5/65/35 samples, respectively. The shortest relaxation time is about 10{sup -12} s and it remains almost temperature independent. Similar behaviour was observed in dipolar glasses betaine phosphate betaine phosphite (BP/BPI). Much more information was obtained from two dimensional distribution of the relaxation times. This confirmed Meyer-Neldel law in relaxors and dipolar glasses. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
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.
Scheduling transactions in mobile distributed real-time database systems
Institute of Scientific and Technical Information of China (English)
LEI Xiang-dong; ZHAO Yue-long; CHEN Song-qiao; YUAN Xiao-li
2008-01-01
A DMVOCC-MVDA (distributed multiversion optimistic concurrency control with multiversion dynamic adjustment) protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments. At the mobile hosts, all transactions perform local pre-validation. The local pre-validation process is carried out against the committed transactions at the server in the last broadcast cycle. Transactions that survive in local pre-validation must be submitted to the server for local final validation. The new protocol eliminates conflicts between mobile read-only and mobile update transactions, and resolves data conflicts flexibly by using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions.Mobile read-only transactions can be committed with no-blocking, and respond time of mobile read-only transactions is greatly shortened. The tolerance of mobile transactions of disconnections from the broadcast channel is increased. In global validation mobile distributed transactions have to do check to ensure distributed serializability in all participants. The simulation results show that the new concurrency control protocol proposed offers better performance than other protocols in terms of miss rate, restart rate,commit rate. Under high work load (think time is 1s) the miss rate of DMVOCC-MVDA is only 14.6%, is significantly lower than that of other protocols. The restart rate of DMVOCC-MVDA is only 32.3%, showing that DMVOCC-MVDA can effectively reduce the restart rate of mobile transactions. And the commit rate of DMVOCC-MVDA is up to 61.2%, which is obviously higher than that of other protocols.
Inversion of generalized relaxation time distributions with optimized damping parameter
Florsch, Nicolas; Revil, André; Camerlynck, Christian
2014-10-01
Retrieving the Relaxation Time Distribution (RDT), the Grains Size Distribution (GSD) or the Pore Size Distribution (PSD) from low-frequency impedance spectra is a major goal in geophysics. The “Generalized RTD” generalizes parametric models like Cole-Cole and many others, but remains tricky to invert since this inverse problem is ill-posed. We propose to use generalized relaxation basis function (for instance by decomposing the spectra on basis of generalized Cole-Cole relaxation elements instead of the classical Debye basis) and to use the L-curve approach to optimize the damping parameter required to get smooth and realistic inverse solutions. We apply our algorithm to three examples, one synthetic and two real data sets, and the program includes the possibility of converting the RTD into GSD or PSD by choosing the value of the constant connecting the relaxation time to the characteristic polarization size of interest. A high frequencies (typically above 1 kHz), a dielectric term in taken into account in the model. The code is provided as an open Matlab source as a supplementary file associated with this paper.
Generalized Poisson-Lindely Distribution in Promotion Time Cure Model
Directory of Open Access Journals (Sweden)
Ahmad Reza Baghestani
2014-12-01
Full Text Available 1024x768 Long-term survival analysis has been improved in the last decade and most of the models concentrate on the promotion time cure model that proposed by Chen (1999. These models are based on the distribution of latent variable N, number of initiated node cells. In this paper we proposed a Generalized Poisson-Lindely distribution that is another option instead of Negative Binomial distribution when there is overdispersion. The results indicated a better fitness compared to others, because of its more flexibility. Parameter estimation has been done by Bayesian approach, in a real data set and a simulation study has shown the advantages of proposed model. Normal 0 false false false /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;}
Right Skewed Distribution of Activity Times in PERT
Directory of Open Access Journals (Sweden)
N.Ravi Shankar,
2011-04-01
Full Text Available A usual supposition in project management is that the distribution for most activities in a project network is right skewed. The prime objective of this paper is to find new path float in Program Evaluation and Review Technique (PERT for right skewed distribution of activity times in a project network. The new path float concept will bring useful planning information to the decision managers and the planners in the project construction. Our new path float in PERT are compared with normal, lognormal approximations with two parameters and also with beta approximations with three parameters. The comparison reveals that beta approximations with three parameters performs better than normal and lognormal approximations suggested.
Distributed Detection over Time Varying Networks: Large Deviations Analysis
Bajovic, Dragana; Xavier, Joao; Sinopoli, Bruno; Moura, Jose M F
2010-01-01
We apply large deviations theory to study asymptotic performance of running consensus distributed detection in sensor networks. Running consensus is a stochastic approximation type algorithm, recently proposed. At each time step k, the state at each sensor is updated by a local averaging of the sensor's own state and the states of its neighbors (consensus) and by accounting for the new observations (innovation). We assume Gaussian, spatially correlated observations. We allow the underlying network be time varying, provided that the graph that collects the union of links that are online at least once over a finite time window is connected. This paper shows through large deviations that, under stated assumptions on the network connectivity and sensors' observations, the running consensus detection asymptotically approaches in performance the optimal centralized detection. That is, the Bayes probability of detection error (with the running consensus detector) decays exponentially to zero as k goes to infinity at...
Indoor environmental quality in French dwellings and building characteristics
Langer, Sarka; Ramalho, Olivier; Derbez, Mickaël; Ribéron, Jacques; Kirchner, Severine; Mandin, Corinne
2016-03-01
A national survey on indoor environmental quality covering 567 residences in mainland France was performed during 2003-2005. The measured parameters were temperature, relative humidity, CO2, and the indoor air pollutants: fourteen individual volatile organic compounds (VOC), four aldehydes and particulate matter PM10 and PM2.5. The measured indoor concentrations were analyzed for correlations with the building characteristics: type of dwelling, period of construction, dwelling location, type of ventilation system, building material, attached garage and retrofitting. The median night time air exchange rate (AER) for all dwellings was 0.44 h-1. The night time AER was higher in apartments (median = 0.49 h-1) than in single-family houses (median = 0.41 h-1). Concentration of formaldehyde was approximately 30% higher in dwellings built after 1990 compared with older ones; it was higher in dwellings with mechanical ventilation and in concrete buildings. The VOC concentrations depended on the building characteristics to various extents. The sampling season influenced the majority of the indoor climate parameters and the concentrations of the air pollutants to a higher degree than the building characteristics. Multivariate linear regression models revealed that the indoor-outdoor difference in specific humidity, a proxy for number of occupants and their indoor activities, remained a significant predictor for most gaseous and particulate air pollutants. The other strong predictors were outdoor concentration, smoking, attached garage and AER (in descending order).
Directional short-time Fourier transform of distributions
Directory of Open Access Journals (Sweden)
Katerina Hadzi-Velkova Saneva
2016-04-01
Full Text Available Abstract In this paper we consider the directional short-time Fourier transform (DSTFT that was introduced and investigated in (Giv in J. Math. Anal. Appl. 399:100-107, 2013. We analyze the DSTFT and its transpose on test function spaces S ( R n $\\mathcal {S}(\\mathbb {R}^{n}$ and S ( Y 2 n $\\mathcal {S}(\\mathbb {Y}^{2n}$ , respectively, and prove the continuity theorems on these spaces. Then the obtained results are used to extend the DSTFT to spaces of distributions.
Theory and practice of runoff space-time distribution
Institute of Scientific and Technical Information of China (English)
WANG; Hao; WANG; Chengming; WANG; Jianhua; QIN; Dayong; ZH
2004-01-01
Based on the domestic and foreign concerning researches, this paper submits the runoff space-time distribution theory which shows evident scientific significances and powerful practical functions. On the basis of digital basin unit cell deriving from the digital elevation model (DEM) and assumption of linear confluence, this theory has been applied successfully to the runoff correlation researches in humid regions. In order to prove the adaptability of the theory in arid and semi-drought regions,this paper is used to the runoff correlation analysis in Wuding River basin--a tributary of Yellow River Basin, and has gained preliminary effective verification.
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.
Topology Identification of General Dynamical Network with Distributed Time Delays
Institute of Scientific and Technical Information of China (English)
WU Zhao-Yan; FU Xin-Chu
2009-01-01
General dynamical networks with distributed time delays are studied. The topology of the networks are viewed as unknown parameters, which need to be identified. Some auxiliary systems (also called the network estimators)are designed to achieve this goal. Both linear feedback control and adaptive strategy are applied in designing these network estimators. Based on linear matrix inequalities and the Lyapunov function method, the sufficient condition for the achievement of topology identification is obtained. This method can also better monitor the switching topology of dynamical networks. Illustrative examples are provided to show the effectiveness of this method.
Modeling hyporheic exchange and in-stream transport with time-varying transit time distributions
Ball, A.; Harman, C. J.; Ward, A. S.
2014-12-01
Transit time distributions (TTD) are used to understand in-stream transport and exchange with the hyporheic zone by quantifying the probability of water (and of dissolved material) taking time T to traverse the stream reach control volume. However, many studies using this method assume a TTD that is time-invariant, despite the time-variability of the streamflow. Others assume that storage is 'randomly sampled' or 'well-mixed' with a fixed volume or fixed exchange rate. Here we present a formulation for a time-variable TTD that relaxes both the time-invariant and 'randomly sampled' assumptions and only requires a few parameters. The framework is applied to transient storage, representing some combination of in-stream and hyporheic storage, along a stream reach. This approach does not assume that hyporheic and dead-zone storage is fixed or temporally-invariant, and allows for these stores to be sampled in more physically representative ways determined by the system itself. Instead of using probability distributions of age, probability distributions of storage (ranked by age) called Ω functions are used to describe how the off-stream storage is sampled in the outflow. Here the Ω function approach is used to describe hyporheic exchange during diurnal fluctuations in streamflow in a gaining reach of the H.J. Andrews Experimental Forest. The breakthrough curves of salt slugs injected four hours apart over a 28-hour period show a systematic variation in transit time distribution. This new approach allows us to relate these salt slug TTDs to a corresponding time-variation in the Ω function, which can then be related to changes in in-stream storage and hyporheic zone mobilization under varying flow conditions. Thus, we can gain insights into how channel storage and hyporheic exchange are changing through time without having to specify difficult to measure or unmeasurable quantities of our system, such as total storage.
Time and temporality: linguistic distribution in human life-games
DEFF Research Database (Denmark)
Cowley, Stephen
2014-01-01
, we find that, in each case, parties shift between close attention to the lived situation and using resources--especially wordings--to manage temporality. It is concluded that the multi-scalar nature of language enables individuals to orchestrate their lives in ways that are, at once, social......While clock-time can be used to clarify facts, all living systems construct their own temporalities. Having illustrated the claim for foxtail grasses, it is argued that, with motility and brains, organisms came to use temporalities that build flexibility into behavior. With the rise of human...... culture, individuals developed a knack of using linguistic distribution to link metabolism with collective ways of assessing and managing experience. Of human temporal management, the best known case is the mental time travel enabled by, among other functions, autobiographical memory. One contribution...
Optimal Time-Reversed Wideband Signals for Distributed Sensing
Kim, Jerry; Mokole, Eric
2015-01-01
This paper considers a distributed wave-based sensing system that probes a scene consisting of multiple interacting idealized targets. Each sensor is a collocated transmit-receive pair that is capable of transmitting arbitrary wideband waveforms. We address the problem of finding the space-time transmit waveform that provides the best target detection performance in the sense of maximizing the energy scattered back into the receivers. Our approach is based on earlier work that constructed the solution by an iterative time-reversal (TR) process. In particular, for the case of idealized point-like scatterers in free space, we examine the frequency dependence of the eigenvalues of the TR operator, and we show that their behavior depends on constructive and destructive interference of the waves traveling along different paths. In addition, we show how these eigenvalues are connected to the poles of the Singularity Expansion Method. Our study of the frequency behavior distinguishes this work from most previous TR ...
Continuous time modelling of dynamical spatial lattice data observed at sparsely distributed times
DEFF Research Database (Denmark)
Rasmussen, Jakob Gulddahl; Møller, Jesper
2007-01-01
Summary. We consider statistical and computational aspects of simulation-based Bayesian inference for a spatial-temporal model based on a multivariate point process which is only observed at sparsely distributed times. The point processes are indexed by the sites of a spatial lattice, and they ex......Summary. We consider statistical and computational aspects of simulation-based Bayesian inference for a spatial-temporal model based on a multivariate point process which is only observed at sparsely distributed times. The point processes are indexed by the sites of a spatial lattice......, and they exhibit spatial interaction. For specificity we consider a particular dynamical spatial lattice data set which has previously been analysed by a discrete time model involving unknown normalizing constants. We discuss the advantages and disadvantages of using continuous time processes compared...
DEFF Research Database (Denmark)
Marinescu, Sorin Ovidiu; Tamas-Selicean, Domitian; Acretoaie, Vlad;
In this paper we are interested in the timing analysis of mixed-criticality embedded real-time applications mapped on distributed heterogeneous architectures. Mixedcriticality tasks can be integrated onto the same architecture only if there is enough spatial and temporal separation among them. We...... in partitions using fixedpriority preemptive scheduling. We have extended the stateof- the-art algorithms for schedulability analysis to take into account the partitions. The proposed algorithm has been evaluated using several synthetic and real-life benchmarks....
Real-Time Verification of Integrity Policies for Distributed Systems
Directory of Open Access Journals (Sweden)
Ernesto Buelna
2013-12-01
Full Text Available We introduce a mechanism for the verification of real-time integrity policies about the operation of a distributed system. Our mechanism is based on Microsoft .NET technologies. Unlike rival competitors, it is not intrusive, as it hardly modifies the source code of any component of the system to be monitored. Our mechanism consists of four modules: the specification module, which comes with a security policy specification language, geared towards the capture of integrity policies; the monitoring module, which includes a code injector, whereby the mechanism observes how specific methods of the system, referred to by some policy, are invoked; the verifier module, which examines the operation of the distributed system in order to determine whether is policy compliant or not; and, the reporter module, which notifies the system is policy compliant, or sends an alert upon the occurrence of a contingency, indicating policy violation. We argue that our mechanism can be framed within the Clark and Wilson security model, and, thus, used to realise information integrity. We illustrate the workings and the power of our mechanism on a simple, but industrial-strength, case study.
Specificity and completion time distributions of biochemical processes
Energy Technology Data Exchange (ETDEWEB)
Munsky, Brian [Los Alamos National Laboratory; Nemenman, Ilya [Los Alamos National Laboratory; Bel, Golan [Los Alamos National Laboratory
2009-01-01
In order to produce specific complex structures from a large set of similar biochemical building blocks, many biochemical systems require high sensitivity to small molecular differences. The first and most common mqdel used to explain this high specificity is kinetic proofreading, which has been extended to a variety of systems from detection of DNA mismatch to cell signaling processes. While the specification properties of the kinetic proofreading model are well known and were studied in various contexts, very little is known about its temporal behavior. In this work, we study the dynamical properties of discrete stochastic two-branch kinetic proofreading schemes. Using the Laplace transform of the corresponding chemical master equation, we obtain an analytical solution for the completion time distribution. In particular we provide expressions for the specificity and the mean and the variance of the process completion times. We also show that, for a wide range of parameters a process distinguishing between two different products can be reduced to a much simpler three point process. Our results allow for the systematic study of the interplay between specificity and completion times as well as testing the validity of the kinetic proofreading model in biological systems.
The delayed time distribution of massive double compact star mergers
Mennekens, N
2016-01-01
In order to investigate the temporal evolution of binary populations in general, double compact star binaries and mergers in particular within a galactic evolution context, a most straightforward method is obviously the implementation of a detailed binary evolutionary model in a galactic chemical evolution code. To our knowledge, only the Brussels galactic code explicitly accounts for binaries. With a galactic code that does not explicitly include binaries, the temporal evolution of the population of double compact star binaries and mergers can be estimated with reasonable accuracy if the delayed time distribution (DTD) for these mergers is available. The DTD for supernovae type Ia has been studied extensively the last decade. In the present paper we present the DTD for merging double neutron star binaries and mixed systems consisting of a neutron star and a black hole. The latter mergers are very promising sites for the production of r-process elements and the DTDs can be used to study the galactic evolution...
A novel time stamping technique for distributed data acquisition systems.
Subramaniam, E T
2012-12-01
In this paper, we discuss the design and implementation of a synchronizing technique for data acquisition systems, which can effectively use the normal, standard local area network cables to provide a time stamp, with a range up to 32 days, resolution of 10 ns, and synchronization within ± 5 ns. This system may be used to synchronize data being collected by independent heterogeneous data acquisition modules, that acquire events independently. Such distributed systems are generally designed with a tree-like structure or independent self-triggered acquisition boxes. These leaf edges are connected through branches to the root node, via non-bus based inter-connecting links. The present system has been tested with a set of self-triggered digital signal processing based data acquisition engines, having a 100 MHz analog to digital converter front end.
Britten, Laura; Addington, Christine; Astill, Sarah
2017-04-11
Falls are a common cause of injury in older adults, with the prevention of falls being a priority for public health departments around the world. This study investigated the feasibility, and impact of an 8 week contemporary dance programme on modifiable physical (physical activity status, mobility, sedentary behaviour patterns) and psychosocial (depressive state, fear of falling) risk factors for falls. An uncontrolled 'pre-post' intervention design was used. Three groups of older (60 yrs.+) adults were recruited from local community groups to participate in a 3 separate, 8 week dance programmes. Each programme comprised two, 90 min dance classes per week. Quantitative measures of physical activity, sedentary behaviour, depression, mobility and fear of falling were measured at baseline (T1) and after 8 weeks of dance (T2). Weekly attendance was noted, and post-study qualitative work was conducted with participants in 3 separate focus groups. A combined thematic analysis of these data was conducted. Of the 38 (Mean Age = 77.3 ± 8.4 yrs., 37 females) who attended the dance sessions, 22 (21 females; 1 male; mean age = 74.8, ±8.44) consented to be part of the study. Mean attendance was 14.6 (±2.6) sessions, and mean adherence was 84.3% (±17). Significant increases in moderate and vigorous physical activity were noted, with a significant decrease in sitting time over the weekdays (p dance programme as a means of being active, health Benefits, and dance-related barriers and facilitators. The recruitment of older adults, good adherence and favourability across all three sites indicate that a dance programme is feasible as an intervention, but this may be limited to females only. Contemporary dance has the potential to positively affect the physical activity, sitting behaviour, falls related efficacy, mobility and incidence of depression in older females which could reduce their incidence of falls. An adequately powered study with control groups are
Distributed digital real-time control system for TCV tokamak
Energy Technology Data Exchange (ETDEWEB)
Le, H.B. [École Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Association EURATOM-Confédération Suisse, CH-1015 Lausanne (Switzerland); Felici, F. [Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Paley, J.I.; Duval, B.P.; Moret, J.-M.; Coda, S.; Sauter, O.; Fasel, D.; Marmillod, P. [École Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Association EURATOM-Confédération Suisse, CH-1015 Lausanne (Switzerland)
2014-03-15
Highlights: • A new distributed digital control system for the TCV tokamak has been commissioned. • Data is shared in real-time between all nodes using the reflective memory. • The customised Linux OS allows achieving deterministic and low latency behaviour. • The control algorithm design in Simulink together with the automatic code generation using Embedded Coder allow rapid algorithm development. • Controllers designed outside the TCV environment can be ported easily. • The previous control system functions have been emulated and improved. • New capabilities include MHD control, profile control, equilibrium reconstruction. - Abstract: A new digital feedback control system (named the SCD “Système de Contrôle Distribué”) has been developed, integrated and used successfully to control TCV (Tokamak à Configuration Variable) plasmas. The system is designed to be modular, distributed, and scalable, accommodating hundreds of diagnostic inputs and actuator outputs. With many more inputs and outputs available than previously possible, it offers the possibility to design advanced control algorithms with better knowledge of the plasma state and to coherently control all TCV actuators, including poloidal field (PF) coils, gas valves, the gyrotron powers and launcher angles of the electron cyclotron heating and current drive system (ECRH/ECCD) together with diagnostic triggering signals. The system consists of multiple nodes; each is a customised Linux desktop or embedded PC which may have local ADC and DAC cards. Each node is also connected to a memory network (reflective memory) providing a reliable, deterministic method of sharing memory between all nodes. Control algorithms are programmed as block diagrams in Matlab-Simulink providing a powerful environment for modelling and control design. The C code is generated automatically from the Simulink block diagram and compiled, with the Simulink Embedded Coder (SEC, formerly Real-Time Workshop Embedded
Characterizing groundwater contribution to lowland streams using Travel Time Distribution
Petrus Kaandorp, Vincentius; Gerardus Bernardus de Louw, Petrus; Kuijper, Martina Johanna Maria; Broers, Hans Peter
2015-04-01
approach in which the groundwater contribution is specified based on travel times. The travel time distribution of groundwater input was calculated for several bigger and smaller streams in the Regge and Dinkel lowland catchment in The Netherlands using a coupled groundwater-surface water model and linked to physical catchment characteristics. More knowledge about the groundwater contribution provides water managers with insights which would help improve the ecological status of streams.
Real-time Control Mediation in Agile Distributed Software Development
DEFF Research Database (Denmark)
Persson, John Stouby; Aaen, Ivan; Mathiassen, Lars
2008-01-01
Agile distributed environments pose particular challenges related to control of quality and collaboration in software development. Moreover, while face-to-face interaction is fundamental in agile development, distributed environments must rely extensively on mediated interactions. On this backdro...
Spatially Distributed Characterization of Soil Dynamics Using Travel-Time Distributions
Hesse, Falk; Zink, Matthias; Attinger, Sabine
2016-04-01
The description of storage and transport of both water and solved contaminants in catchments is very difficult due to the high heterogeneity of the subsurface properties that govern their fate. This heterogeneity, combined with a generally limited knowledge about the subsurface, results in high degrees of uncertainty. As a result, stochastic methods are increasingly applied, where the relevant processes are modeled as being random. Within these methods, quantities like the catchment travel or residence time of a water parcel are described using probability density functions (PDF). The derivation of these PDF's is typically done by using the water fluxes and states of the catchment. A successful application of such frameworks is therefore contingent on a good quantification of these fluxes and states across the different spatial scales. The objective of this study is to use travel times for the characterization of an ca. 1000 square kilometer, humid catchment in Central Germany. To determine the states and fluxes, we apply the mesoscale Hydrological Model mHM, a spatially distributed hydrological model to the catchment. Using detailed data of precipitation, land cover, morphology and soil type as inputs, mHM is able to determine fluxes like recharge and evapotranspiration and states like soil moisture as outputs. Using these data, we apply the above theoretical framework to our catchment. By virtue of the aforementioned properties of mHM, we are able to describe the storage and release of water with a high spatial resolution. This allows for a comprehensive description of the flow and transport dynamics taking place in the catchment. The spatial distribution of such dynamics is then compared with land cover and soil moisture maps as well as driving forces like precipitation and potential evapotranspiration to determine the most predictive factors. In addition, we investigate how non-local data like the age distribution of discharge flows are impacted by, and
Spatially Distributed Characterization of Catchment Dynamics Using Travel-Time Distributions
Heße, F.; Zink, M.; Attinger, S.
2015-12-01
The description of storage and transport of both water and solved contaminants in catchments is very difficult due to the high heterogeneity of the subsurface properties that govern their fate. This heterogeneity, combined with a generally limited knowledge about the subsurface, results in high degrees of uncertainty. As a result, stochastic methods are increasingly applied, where the relevant processes are modeled as being random. Within these methods, quantities like the catchment travel or residence time of a water parcel are described using probability density functions (PDF). The derivation of these PDF's is typically done by using the water fluxes and states of the catchment. A successful application of such frameworks is therefore contingent on a good quantification of these fluxes and states across the different spatial scales. The objective of this study is to use travel times for the characterization of an ca. 1000 square kilometer, humid catchment in Central Germany. To determine the states and fluxes, we apply the mesoscale Hydrological Model mHM, a spatially distributed hydrological model to the catchment. Using detailed data of precipitation, land cover, morphology and soil type as inputs, mHM is able to determine fluxes like recharge and evapotranspiration and states like soil moisture as outputs. Using these data, we apply the above theoretical framework to our catchment. By virtue of the aforementioned properties of mHM, we are able to describe the storage and release of water with a high spatial resolution. This allows for a comprehensive description of the flow and transport dynamics taking place in the catchment. The spatial distribution of such dynamics is then compared with land cover and soil moisture maps as well as driving forces like precipitation and temperature to determine the most predictive factors. In addition, we investigate how non-local data like the age distribution of discharge flows are impacted by, and therefore allow to infer
A comparative study of indoor radon concentrations between dwellings and schools
Kapdan, E.; Altinsoy, N.
2012-04-01
The aim of this study is to determine the relationship of radon concentrations between dwellings and the schools located in the same regions and to obtain related indoor average radon concentration dwelling-school correction factor for similar locations. The research has been carried out by determining indoor radon concentrations at schools and dwellings located at the same districts in the selected two separate research fields called The Former Adapazari region and The New Adapazari region in the city of Adapazari using a total of 81 Cr-39 passive radon detectors for 75 days. The average radon concentrations have been determined for the dwellings and the schools in 15 districts of the Former Adapazari region as 59.9 Bq m-3 and 57.1 Bq m-3, respectively. The results in 4 districts of the New Adapazari region were 63.5 Bq m-3 for the dwellings and 61.0 Bq m-3 for the schools. Moreover, the annual effective doses were calculated as 1.33 mSv/y and 1.41 mSv/y for the dwellings of Former Adapazari and New Adapazari, respectively. It was seen that the doses received in the dwellings are about four times the doses received in the schools. The indoor radon concentration dwelling-school correction factor was found to be 1.04±0.01 for the research area.
Estimation Accuracy on Execution Time of Run-Time Tasks in a Heterogeneous Distributed Environment
Directory of Open Access Journals (Sweden)
Qi Liu
2016-08-01
Full Text Available Distributed Computing has achieved tremendous development since cloud computing was proposed in 2006, and played a vital role promoting rapid growth of data collecting and analysis models, e.g., Internet of things, Cyber-Physical Systems, Big Data Analytics, etc. Hadoop has become a data convergence platform for sensor networks. As one of the core components, MapReduce facilitates allocating, processing and mining of collected large-scale data, where speculative execution strategies help solve straggler problems. However, there is still no efficient solution for accurate estimation on execution time of run-time tasks, which can affect task allocation and distribution in MapReduce. In this paper, task execution data have been collected and employed for the estimation. A two-phase regression (TPR method is proposed to predict the finishing time of each task accurately. Detailed data of each task have drawn interests with detailed analysis report being made. According to the results, the prediction accuracy of concurrent tasks’ execution time can be improved, in particular for some regular jobs.
Estimation Accuracy on Execution Time of Run-Time Tasks in a Heterogeneous Distributed Environment
Liu, Qi; Cai, Weidong; Jin, Dandan; Shen, Jian; Fu, Zhangjie; Liu, Xiaodong; Linge, Nigel
2016-01-01
Distributed Computing has achieved tremendous development since cloud computing was proposed in 2006, and played a vital role promoting rapid growth of data collecting and analysis models, e.g., Internet of things, Cyber-Physical Systems, Big Data Analytics, etc. Hadoop has become a data convergence platform for sensor networks. As one of the core components, MapReduce facilitates allocating, processing and mining of collected large-scale data, where speculative execution strategies help solve straggler problems. However, there is still no efficient solution for accurate estimation on execution time of run-time tasks, which can affect task allocation and distribution in MapReduce. In this paper, task execution data have been collected and employed for the estimation. A two-phase regression (TPR) method is proposed to predict the finishing time of each task accurately. Detailed data of each task have drawn interests with detailed analysis report being made. According to the results, the prediction accuracy of concurrent tasks’ execution time can be improved, in particular for some regular jobs. PMID:27589753
Estimation Accuracy on Execution Time of Run-Time Tasks in a Heterogeneous Distributed Environment.
Liu, Qi; Cai, Weidong; Jin, Dandan; Shen, Jian; Fu, Zhangjie; Liu, Xiaodong; Linge, Nigel
2016-08-30
Distributed Computing has achieved tremendous development since cloud computing was proposed in 2006, and played a vital role promoting rapid growth of data collecting and analysis models, e.g., Internet of things, Cyber-Physical Systems, Big Data Analytics, etc. Hadoop has become a data convergence platform for sensor networks. As one of the core components, MapReduce facilitates allocating, processing and mining of collected large-scale data, where speculative execution strategies help solve straggler problems. However, there is still no efficient solution for accurate estimation on execution time of run-time tasks, which can affect task allocation and distribution in MapReduce. In this paper, task execution data have been collected and employed for the estimation. A two-phase regression (TPR) method is proposed to predict the finishing time of each task accurately. Detailed data of each task have drawn interests with detailed analysis report being made. According to the results, the prediction accuracy of concurrent tasks' execution time can be improved, in particular for some regular jobs.
Wave characterization for mammalian cell culture: residence time distribution.
Rodrigues, Maria Elisa; Costa, Ana Rita; Henriques, Mariana; Azeredo, Joana; Oliveira, Rosário
2012-02-15
The high dose requirements of biopharmaceutical products led to the development of mammalian cell culture technologies that increase biomanufacturing capacity. The disposable Wave bioreactor is one of the most promising technologies, providing ease of operation and no cross-contamination, and using an innovative undulation movement that ensures good mixing and oxygen transfer without cell damage. However, its recentness demands further characterization. This study evaluated the residence time distribution (RTD) in Wave, allowing the characterization of mixing and flow and the comparison with ideal models and a Stirred tank reactor (STR) used for mammalian cell culture. RTD was determined using methylene blue with pulse input methodology, at three flow rates common in mammalian cell culture (3.3×10(-5)m(3)/h, 7.9×10(-5)m(3)/h, and 1.25×10(-4)m(3)/h) and one typical of microbial culture (5×10(-3)m(3)/h). Samples were taken periodically and the absorbance read at 660nm. It was observed that Wave behavior diverted from ideal models, but was similar to STR. Therefore, the deviations are not related to the particular Wave rocking mechanism, but could be associated with the inadequacy of these reactors to operate in continuous mode or to a possible inability of the theoretical models to properly describe the behavior of reactors designed for mammalian cell culture. Thus, the development of new theoretical models could better characterize the performance of these reactors.
Cybersecurity through Real-Time Distributed Control Systems
Energy Technology Data Exchange (ETDEWEB)
Kisner, Roger A [ORNL; Manges, Wayne W [ORNL; MacIntyre, Lawrence Paul [ORNL; Nutaro, James J [ORNL; Munro Jr, John K [ORNL; Ewing, Paul D [ORNL; Howlader, Mostofa [ORNL; Kuruganti, Phani Teja [ORNL; Wallace, Richard M [ORNL; Olama, Mohammed M [ORNL
2010-04-01
Critical infrastructure sites and facilities are becoming increasingly dependent on interconnected physical and cyber-based real-time distributed control systems (RTDCSs). A mounting cybersecurity threat results from the nature of these ubiquitous and sometimes unrestrained communications interconnections. Much work is under way in numerous organizations to characterize the cyber threat, determine means to minimize risk, and develop mitigation strategies to address potential consequences. While it seems natural that a simple application of cyber-protection methods derived from corporate business information technology (IT) domain would lead to an acceptable solution, the reality is that the characteristics of RTDCSs make many of those methods inadequate and unsatisfactory or even harmful. A solution lies in developing a defense-in-depth approach that ranges from protection at communications interconnect levels ultimately to the control system s functional characteristics that are designed to maintain control in the face of malicious intrusion. This paper summarizes the nature of RTDCSs from a cybersecurity perspec tive and discusses issues, vulnerabilities, candidate mitigation approaches, and metrics.
LPI Radar Waveform Recognition Based on Time-Frequency Distribution.
Zhang, Ming; Liu, Lutao; Diao, Ming
2016-10-12
In this paper, an automatic radar waveform recognition system in a high noise environment is proposed. Signal waveform recognition techniques are widely applied in the field of cognitive radio, spectrum management and radar applications, etc. We devise a system to classify the modulating signals widely used in low probability of intercept (LPI) radar detection systems. The radar signals are divided into eight types of classifications, including linear frequency modulation (LFM), BPSK (Barker code modulation), Costas codes and polyphase codes (comprising Frank, P1, P2, P3 and P4). The classifier is Elman neural network (ENN), and it is a supervised classification based on features extracted from the system. Through the techniques of image filtering, image opening operation, skeleton extraction, principal component analysis (PCA), image binarization algorithm and Pseudo-Zernike moments, etc., the features are extracted from the Choi-Williams time-frequency distribution (CWD) image of the received data. In order to reduce the redundant features and simplify calculation, the features selection algorithm based on mutual information between classes and features vectors are applied. The superiority of the proposed classification system is demonstrated by the simulations and analysis. Simulation results show that the overall ratio of successful recognition (RSR) is 94.7% at signal-to-noise ratio (SNR) of -2 dB.
LPI Radar Waveform Recognition Based on Time-Frequency Distribution
Directory of Open Access Journals (Sweden)
Ming Zhang
2016-10-01
Full Text Available In this paper, an automatic radar waveform recognition system in a high noise environment is proposed. Signal waveform recognition techniques are widely applied in the field of cognitive radio, spectrum management and radar applications, etc. We devise a system to classify the modulating signals widely used in low probability of intercept (LPI radar detection systems. The radar signals are divided into eight types of classifications, including linear frequency modulation (LFM, BPSK (Barker code modulation, Costas codes and polyphase codes (comprising Frank, P1, P2, P3 and P4. The classifier is Elman neural network (ENN, and it is a supervised classification based on features extracted from the system. Through the techniques of image filtering, image opening operation, skeleton extraction, principal component analysis (PCA, image binarization algorithm and Pseudo–Zernike moments, etc., the features are extracted from the Choi–Williams time-frequency distribution (CWD image of the received data. In order to reduce the redundant features and simplify calculation, the features selection algorithm based on mutual information between classes and features vectors are applied. The superiority of the proposed classification system is demonstrated by the simulations and analysis. Simulation results show that the overall ratio of successful recognition (RSR is 94.7% at signal-to-noise ratio (SNR of −2 dB.
Distributed Space Time Coding for Wireless Two-way Relaying
Muralidharan, Vijayvaradharaj T
2012-01-01
We consider the wireless two-way relay channel, in which two-way data transfer takes place between the end nodes with the help of a relay. For the Denoise-And-Forward (DNF) protocol, it was shown by Koike-Akino et. al. that adaptively changing the network coding map used at the relay greatly reduces the impact of Multiple Access interference at the relay. The harmful effect of the deep channel fade conditions can be effectively mitigated by proper choice of these network coding maps at the relay. Alternatively, in this paper we propose a Distributed Space Time Coding (DSTC) scheme, which effectively removes most of the deep fade channel conditions at the transmitting nodes itself without any CSIT and without any need to adaptively change the network coding map used at the relay. It is shown that the deep fades occur when the channel fade coefficient vector falls in a finite number of vector subspaces of $\\mathbb{C}^2$, which are referred to as the singular fade subspaces. DSTC design criterion referred to as ...
Reconstruction of relaxation time distribution from linear electrochemical impedance spectroscopy
Zhang, Yanxiang; Chen, Yu; Yan, Mufu; Chen, Fanglin
2015-06-01
Linear electrochemical impedance spectroscopy (EIS), and in particular its representation of distribution of relaxation time (DRT), enables the identification of the number of processes and their nature involved in electrochemical cells. With the advantage of high frequency resolution, DRT has recently drawn increasing attention for applications in solid oxide fuel cells (SOFCs). However, the method of DRT reconstruction is not yet presented clearly in terms of what mathematical treatments and theoretical assumptions have been made. Here we present unambiguously a method to reconstruct DRT function of impedance based on Tikhonov regularization. By using the synthetic impedances and analytic DRT functions of RQ element, generalized finite length Warburg element, and Gerischer element with physical quantities representative to those of SOFC processes, we show that the quality of DRT reconstruction is sensitive to the sampling points per decade (ppd) of frequency from the impedance measurement. The robustness of the DRT reconstruction to resist noise imbedded in impedance data and numerical calculations can be accomplished by optimizing the weighting factor λ according to well defined criterion.
A search profile for dwellings with elevated radon levels
DEFF Research Database (Denmark)
Damkjær, A.; Andersen, C.E.; Majborn, B.;
1996-01-01
basement/slab-on-grade foundation built on either fractured granitic basement rocks, or fractured limestone. Clayey till areas were also included in the profile in order to confirm earlier findings. Three areas representing these surface geologies were selected for indoor radon measurements with CR-39...... track detectors, and a total of 200 houses matching the profile underwent radon measurements during the winter 1994-95. The distribution of the measured radon concentrations were found in most cases to comply with log-normal distributions. Measurements in the living rooms of houses in each of the three......A search profile for dwellings with elevated radon levels has been employed to investigate possibly radon-prone areas in Denmark and to find houses suitable for radon mitigation studies. The profile is defined as dwellings which are single-family houses with slab-on-grade foundation or partly...
Directory of Open Access Journals (Sweden)
Mir G. H. Talpur
2006-01-01
Full Text Available In this paper we consider, how to find the marginal distributions of crossing time and renewal numbers related with two poisson processes by using probability arguments. The obtained results show that the one-dimension marginal distributions are N+1 order PH-distributions.
Migrating to a real-time distributed parallel simulator architecture- An update
CSIR Research Space (South Africa)
Duvenhage, B
2007-09-01
Full Text Available A legacy non-distributed logical time simulator was previously migrated to a distributed architecture to parallelise execution. The existing Discrete Time System Specification (DTSS) modelling formalism was retained to simplify the reuse of existing...
Real-time Distributed Economic Dispatch forDistributed Generation Based on Multi-Agent System
DEFF Research Database (Denmark)
Luo, Kui; Wu, Qiuwei; Nielsen, Arne Hejde
2015-01-01
The distributed economic dispatch for distributed generation is formulated as a optimization problem with equality and inequality constraints. An effective distributed approach based on multi-agent system is proposed for solving the economic dispatch problem in this paper. The proposed approach...... distributed manner with local computation and communication among neighboring agent. The feasibility and effectiveness of this approach is demonstrated by a numerical test system....
Braun, V M; Mankiewicz, L; Braun, V; Górnicki, P; Mankiewicz, L
1995-01-01
We argue that parton distributions in coordinate space provide a more natural object for nonperturbative methods compared to the usual momentum distributions in which the physics of different longitudinal distances is being mixed. To illustrate the advantages of the coordinate space formulation, we calculate the coordinate space distributions for valence quarks in the proton using the QCD sum rule approach. A remarkable agreement is found between the calculated and the experimentally measured u-quark distribution up to distances of order \\sim 2 fm in the proton rest frame. The standard calculation completely fails, however, for valence d quarks; the reasons for this discrepancy are discussed.
Just-in-time Data Distribution for Analytical Query Processing
Ivanova, M.G.; Kersten, M.L.; Groffen, F.E.
2012-01-01
Distributed processing commonly requires data spread across machines using a priori static or hash-based data allocation. In this paper, we explore an alternative approach that starts from a master node in control of the complete database, and a variable number of worker nodes for delegated
Just-In-Time Data Distribution for Analytical Query Processing
Ivanova, M.; Kersten, M.; Groffen, F.
2012-01-01
Distributed processing commonly requires data spread across machines using a priori static or hash-based data allocation. In this paper, we explore an alternative approach that starts from a master node in control of the complete database, and a variable number of worker nodes for delegated query pr
Time and the Distribution of L2 Instruction.
Collins, Laura; Halter, Randall H.; Lightbown, Patsy M.; Spada, Nina
1999-01-01
Reports the results of research investigating the effectiveness of three types of English-as-Second-Language (ESL) programs in Quebec. Equivalent ESL curricula were taught over the regular 10-month school year in "distributed" programs, over a 5-month period in "massed" programs, and over a 5-month period along with extracurricular activities in…
Institute of Scientific and Technical Information of China (English)
Hong Jin; Teng Shao
2014-01-01
The wind environment around residential building groups is increasingly concerned, while the dwelling groups as the elementary unit of planning design, its quality of surrounding wind environment will directly affect people’ s life. This study based on the climatic conditions of severe cold regions, selects four dwellings groups with different openings scale and position as the research objects, and then simulates and analyzes the wind speed distribution characteristics of each pattern. Meanwhile, it extracts the wind speed values of one hundred points of each pattern and applies the coefficient of uniformity method to the ecological evaluation. It has been found that grouping pattern of buildings has a dramatic effect on the resulting airflow behavior. Configurations that contain a T⁃shaped central space with small opened side can effectively prevent and contain airflow in the site offer. The interactive influence between layout of dwelling groups and wind environment are explored, so as to provide basis for the planning design of dwelling groups.
Liver allocation and distribution: time for a change.
Deshpande, Ranjit; Hirose, Ryutaro; Mulligan, David
2017-04-01
Liver allograft allocation has been a topic of hot debate for over a decade. New redistricting changes have been proposed by the Liver and Intestinal Transplant Committee to the existing United Network for Organ Sharing (UNOS) liver allocation policy. The basis of this new proposal is similar to the old one with an aim to distribute organs in a fair, efficient and equitable fashion. In this review, we plan to look in depth at the redistribution proposals thus far, their merits and how they may help patients who do not have adequate access to livers. Many authors have criticized the proposed changes to organ distribution to reduce geographic disparity in access to liver transplantation. Our focus in this article is to bring forth the most recent literature and proposed changes in the current distribution system. We will also mention two other possible methods that have been proposed to redesign distribution using concentric circles and neighborhoods. In this article, we also look at the economics of the redistricting proposal and its effects on transplant centers. The UNOS Liver and Intestinal Transplant Committee has recommended a proposal using the eight-district model with proximity circles and three additional Model for End-Stage Liver Disease (MELD) points with initial sharing MELD threshold of 25 as a starting point to reduce disparity in patient access to deceased donor livers for transplantation. This proposal has met with significant resistance because of concerns of cost, logistics and impact on existing transplant centers. Other methodologies have also been proposed that have the potential to significantly improve our current disparity of access to life-saving organs. Variation in the supply of donor organs vs. the demand or need for liver transplant by geography and the current defined areas of distribution drive this disparity. Cost benefits to the healthcare system in caring for patients with advanced stages of liver disease may outweigh increased
Catchment residence and travel time distributions: The master equation
National Research Council Canada - National Science Library
Gianluca Botter; Enrico Bertuzzo; Andrea Rinaldo
2011-01-01
Travel/residence time pdf's are related objects with different physical meaning A Master Equation for the residence time pdf is derived and solved analytically We develop a mathematical framework...
Migrating to a real-time distributed parallel simulator architecture
CSIR Research Space (South Africa)
Duvenhage, B
2007-07-01
Full Text Available DEVS. Ogata, et al. [7] tested the real-time performance of DIS and different versions of the RTI-NG HLA Run-Time Infrastructure (RTI). Their real-time vehicle model simulation within a 3D graphi- cal environment reached a frame rate ceiling... to mili- tary training simulation: A guide for discrete event sim- ulationists. In Proceedings of the 1998 Winter Simula- tion Conference, 1998. [7] Michihiko Ogata, Akira Higashide, Mike Cammarano, and Toshinao Takagi. Rti performance...
7 CFR 1435.504 - Timing of distribution of CCC-owned sugar.
2010-01-01
... 7 Agriculture 10 2010-01-01 2010-01-01 false Timing of distribution of CCC-owned sugar. 1435.504... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Processor Sugar Payment-In-Kind (PIK) Program § 1435.504 Timing of distribution of CCC-owned sugar. Distribution of sugar...
Real Time Emulation of Dynamic Tariff for Congestion Management in Distribution Networks
DEFF Research Database (Denmark)
Rasmussen, Theis Bo; Wu, Qiuwei; Huang, Shaojun
2016-01-01
This paper presents the real time evaluation of the dynamic tariff (DT) method for alleviating congestion in a distribution networks with high penetration of distributed energy resources (DERs). The DT method is implemented in a real time digital testing platform that emulates a real distribution...
Time Truncated Testing Strategy using Multiple Testers: Lognormal Distributed Lifetime
Directory of Open Access Journals (Sweden)
Itrat Batool Naqvi
2014-06-01
Full Text Available In this study, group acceptance sampling plan proposed by Aslam et al. (2011 is reconsidered when the lifetime variant of the test item follows lognormal distribution. The optimal plan parameters are obtained by considering various pre-specified parameters. The plan parameters are obtained using the non-linear optimization solution using two points approach. The advantage of the proposed plan is discussed over the existing plan using the single point approach and the proposed plan is more efficient than the existing plan.
Storm blueprints patterns for distributed real-time computation
Goetz, P Taylor
2014-01-01
A blueprints book with 10 different projects built in 10 different chapters which demonstrate the various use cases of storm for both beginner and intermediate users, grounded in real-world example applications.Although the book focuses primarily on Java development with Storm, the patterns are more broadly applicable and the tips, techniques, and approaches described in the book apply to architects, developers, and operations.Additionally, the book should provoke and inspire applications of distributed computing to other industries and domains. Hadoop enthusiasts will also find this book a go
Increased gait unsteadiness in community-dwelling elderly fallers
Hausdorff, J. M.; Edelberg, H. K.; Mitchell, S. L.; Goldberger, A. L.; Wei, J. Y.
1997-01-01
OBJECTIVE: To test the hypothesis that quantitative measures of gait unsteadiness are increased in community-dwelling elderly fallers. STUDY DESIGN: Retrospective, case-control study. SETTING: General community. PARTICIPANTS: Thirty-five community-dwelling elderly subjects older than 70 years of age who were capable of ambulating independently for 6 minutes were categorized as fallers (age, 82.2 +/- 4.9 yrs [mean +/- SD]; n = 18) and nonfallers (age, 76.5 +/- 4.0 yrs; n = 17) based on history; 22 young (age, 24.6 +/- 1.9 yrs), healthy subjects also participated as a second reference group. MAIN OUTCOME MEASURES: Stride-to-stride variability (standard deviation and coefficient of variation) of stride time, stance time, swing time, and percent stance time measured during a 6-minute walk. RESULTS: All measures of gait variability were significantly greater in the elderly fallers compared with both the elderly nonfallers and the young subjects (p < .0002). In contrast, walking speed of the elderly fallers was similar to that of the nonfallers. There were little or no differences in the variability measures of the elderly nonfallers compared with the young subjects. CONCLUSIONS: Stride-to-stride temporal variations of gait are relatively unchanged in community-dwelling elderly nonfallers, but are significantly increased in elderly fallers. Quantitative measurement of gait unsteadiness may be useful in assessing fall risk in the elderly.
DEFF Research Database (Denmark)
Chen, Shuheng; Hu, Weihao; Chen, Zhe
2016-01-01
In this paper, an efficient methodology is proposed to deal with segmented-time reconfiguration problem of distribution networks coupled with segmented-time reactive power control of distributed generators. The target is to find the optimal dispatching schedule of all controllable switches...... and distributed generators’ reactive powers in order to minimize comprehensive cost. Corresponding constraints, including voltage profile, maximum allowable daily switching operation numbers (MADSON), reactive power limits, and so on, are considered. The strategy of grouping branches is used to simplify...... (FAHPSO) is implemented in VC++ 6.0 program language. A modified version of the typical 70-node distribution network and several real distribution networks are used to test the performance of the proposed method. Numerical results show that the proposed methodology is an efficient method for comprehensive...
Exercise and risk of injurious fall in home-dwelling elderly
Iinattiniemi, Sari; Jokelainen, Jari; Luukinen, Heikki
2008-01-01
OBJECTIVES: To examine the relationship between different types of physical exercise and the risk of subsequent fall-related injury. STUDY DESIGN: A prospective study of the home-dwelling elderly. METHODS: A population sample of home-dwelling subjects aged 85 years or older (n = 512) in northern Finland participated in the study. Baseline data were collected by home-nursing staff through postal questionnaires and clinical tests. Frequency and times of physical exercise--that is, walking exe...
Timing and Spatial Distribution of Loess in Xinjiang, NW China.
Directory of Open Access Journals (Sweden)
Yun Li
Full Text Available Central Asia is one of the most significant loess regions on Earth, with an important role in understanding Quaternary climate and environmental change. However, in contrast to the widely investigated loess deposits in the Chinese Loess Plateau, the Central Asian loess-paleosol sequences are still insufficiently known and poorly understood. Through field investigation and review of the previous literature, the authors have investigated the distribution, thickness and age of the Xinjiang loess, and analyzed factors that control these parameters in the Xinjiang in northwest China, Central Asia. The loess sediments cover river terraces, low uplands, the margins of deserts and the slopes of the Tianshan Mountains and Kunlun Mountains and are also present in the Ili Basin. The thickness of the Xinjiang loess deposits varies from several meters to 670 m. The variation trend of the sand fraction (>63 μm grain-size contour can indicate the local major wind directions, so we conclude that the NW and NE winds are the main wind directions in the North and South Xinjiang, and the westerly wind mainly transport dust into the Ili basin. We consider persistent drying, adequate regional wind energy and well-developed river terraces to be the main factors controlling the distribution, thickness and formation age of the Xinjiang loess. The well-outcropped loess sections have mainly developed since the middle Pleistocene in Xinjiang, reflecting the appearance of the persistent drying and the present air circulation system. However, the oldest loess deposits are as old as the beginning of the Pliocene in the Tarim Basin, which suggests that earlier aridification occurred in the Tarim Basin rather than in the Ili Basin and the Junggar Basin.
The VLBA Correlator---Real-Time in the Distributed ERA
Wells, Donald C.
1993-01-01
The Correlator is the signal processing engine of the Very Long Baseline Array [VLBA]. Radio signals are recorded on special wideband digital recorders at the 10 VLBA antennas and are shipped to the Array Operations Center in Socorro, New Mexico, where they are played back simultaneously into the Correlator. Real-time software and firmware controls the playback drives to achieve synchronization, compute models of the wavefront delay, control the numerous modules of the Correlator, and record FITS files of the fringe visibilities at the back-end of the Correlator. The Correlator system contains a total of more than 100 programmable computers, which communicate by means of various protocols. The VLBA Correlator's dependence on network protocols is an example of the radical transformation of the real-time world over the past five years: real-time is becoming more like conventional computing.
Critical capacity, travel time delays and travel time distribution of rapid mass transit systems
Legara, Erika Fille; Monterola, Christopher; Lee, Kee Khoon; Hung, Gih Guang
2014-07-01
We set up a mechanistic agent-based model of a rapid mass transit system. Using empirical data from Singapore's unidentifiable smart fare card, we validate our model by reconstructing actual travel demand and duration of travel statistics. We subsequently use this model to investigate two phenomena that are known to significantly affect the dynamics within the RTS: (1) overloading in trains and (2) overcrowding in the RTS platform. We demonstrate that by varying the loading capacity of trains, a tipping point emerges at which an exponential increase in the duration of travel time delays is observed. We also probe the impact on the rail system dynamics of three types of passenger growth distribution across stations: (i) Dirac delta, (ii) uniform and (iii) geometric, which is reminiscent of the effect of land use on transport. Under the assumption of a fixed loading capacity, we demonstrate the dependence of a given origin-destination (OD) pair on the flow volume of commuters in station platforms.
Representing real time semantics for distributed application integration
Poon, P.M.S.; Dillon, T.S.; Chang, E.; Feng, L.
2006-01-01
Traditional real time system design and development are driven by technological requirements. With the ever growing complexity of requirements and the advances in software design, the alignment of focus has gradually been shifted to the perspective of business and industrial needs. This paper discus
Distributed energy resources scheduling considering real-time resources forecast
DEFF Research Database (Denmark)
Silva, M.; Sousa, T.; Ramos, S.
2014-01-01
grids and considering day-ahead, hour-ahead and realtime time horizons. This method considers that energy resources are managed by a VPP which establishes contracts with their owners. The full AC power flow calculation included in the model takes into account network constraints. In this paper...
Residence time distribution in twin-screw extruders.
Jager, T.
1992-01-01
For the twin-screw extruders used in the food industry at short time high temperature processes the knowledge of their reactor properties is incomplete for mass- and heat flow. Therefore each process change such as: scale-up or product development requires a great number of measurements before an ac
Poverty index with time-varying consumption and income distributions
Chattopadhyay, Amit K.; Kumar, T. Krishna; Mallick, Sushanta K.
2017-03-01
Starting from a stochastic agent-based model to represent market exchange in a developing economy, we study time variations of the probability density function of income with simultaneous variation of the consumption deprivation (CD), where CD represents the shortfall in consumption from the saturation level of an essential commodity, cereal. Together, these two models combine income-expenditure-based market dynamics with time variations in consumption due to income. In this new unified theoretical structure, exchange of trade in assets is only allowed when the income exceeds consumption-deprivation while CD itself is endogenously obtained from a separate kinetic model. Our results reveal that the nature of time variation of the CD function leads to a downward trend in the threshold level of consumption of basic necessities, suggesting a possible dietary transition in terms of lower saturation level of food-grain consumption, possibly through an improvement in the level of living. The new poverty index, defined as CD, is amenable to approximate probabilistic prediction within a short time horizon. A major achievement of this work is the intrinsic independence of the poverty index from an exogenous poverty line, making it more objective for policy formulation as opposed to existing poverty indices in the literature.
Residence time distribution in twin-screw extruders
Jager, T.
1992-01-01
For the twin-screw extruders used in the food industry at short time high temperature processes the knowledge of their reactor properties is incomplete for mass- and heat flow. Therefore each process change such as: scale-up or product development requires a great number of measurements
The VLBA correlator: Real-time in the distributed era
Wells, D. C.
1992-01-01
The correlator is the signal processing engine of the Very Long Baseline Array (VLBA). Radio signals are recorded on special wideband (128 Mb/s) digital recorders at the 10 telescopes, with sampling times controlled by hydrogen maser clocks. The magnetic tapes are shipped to the Array Operations Center in Socorro, New Mexico, where they are played back simultaneously into the correlator. Real-time software and firmware controls the playback drives to achieve synchronization, compute models of the wavefront delay, control the numerous modules of the correlator, and record FITS files of the fringe visibilities at the back-end of the correlator. In addition to the more than 3000 custom VLSI chips which handle the massive data flow of the signal processing, the correlator contains a total of more than 100 programmable computers, 8-, 16- and 32-bit CPUs. Code is downloaded into front-end CPU's dependent on operating mode. Low-level code is assembly language, high-level code is C running under a RT OS. We use VxWorks on Motorola MVME147 CPU's. Code development is on a complex of SPARC workstations connected to the RT CPU's by Ethernet. The overall management of the correlation process is dependent on a database management system. We use Ingres running on a Sparcstation-2. We transfer logging information from the database of the VLBA Monitor and Control System to our database using Ingres/NET. Job scripts are computed and are transferred to the real-time computers using NFS, and correlation job execution logs and status flow back by the route. Operator status and control displays use windows on workstations, interfaced to the real-time processes by network protocols. The extensive network protocol support provided by VxWorks is invaluable. The VLBA Correlator's dependence on network protocols is an example of the radical transformation of the real-time world over the past five years. Real-time is becoming more like conventional computing. Paradoxically, 'conventional
Tunneling time distribution by means of Nelson’s quantum mechanics and wave-particle duality
Indian Academy of Sciences (India)
Koh'Ichiro Hara; Ichiro Ohba
2002-08-01
We construct a tunneling time distribution by means of Nelson’s quantum mechanics and investigate statistical properties of the tunneling time distribution. As a result, we ﬁnd that the relationship between the average and the variance of the tunneling time shows ‘wave-particle duality’.
Ratio limits and limiting conditional distributions for discrete-time birth-death processes
Doorn, van Erik A.; Schrijner, Pauline
1995-01-01
We consider discrete-time birth-death processes with an absorbing state and study the conditional state distribution at time n given that absorption has not occurred by that time but will occur eventually. In particular, we establish conditions for the convergence of these distributions to a proper
A Statistical Approach to Performance Monitoring in Soft Real-Time Distributed Systems
Bickson, Danny; Hoch, Ezra N; Shagin, Konstantin
2009-01-01
Soft real-time applications require timely delivery of messages conforming to the soft real-time constraints. Satisfying such requirements is a complex task both due to the volatile nature of distributed environments, as well as due to numerous domain-specific factors that affect message latency. Prompt detection of the root-cause of excessive message delay allows a distributed system to react accordingly. This may significantly improve compliance with the required timeliness constraints. In this work, we present a novel approach for distributed performance monitoring of soft-real time distributed systems. We propose to employ recent distributed algorithms from the statistical signal processing and learning domains, and to utilize them in a different context of online performance monitoring and root-cause analysis, for pinpointing the reasons for violation of performance requirements. Our approach is general and can be used for monitoring of any distributed system, and is not limited to the soft real-time dom...
Institute of Scientific and Technical Information of China (English)
Qian Bin; Yang Wanlin; Wan Qun
2007-01-01
Under dense urban fading environment, performance of joint multi-path parameter estimation method based on traditional point signal model degrades seriously.In this paper, a new space and time signal model based on multipath distribution function is given after new space and time manifold is reconstructed.Then joint spacetime signal subspace is obtained by converting acquired channel from time domain to frequency domain .Then space and time spectrum is formulated by the space sub-matrix and time sub-matrix taken out of joint space-time signal subspace, and parameters are estimated by searching the minimum eigenvalues of the space matrix and the time matrix.Lastly, A space and time parameters matching process is performed by using the orthogonal property between joint noise subspace and the space-time manifold.In contrast with tradition MUSIC, the algorithm we present here only need two 1- dimension searching and was not sensitive to different distribution function.
DEFF Research Database (Denmark)
Larsén, Xiaoli Guo; Mann, Jakob; Rathmann, Ole
2015-01-01
as a guideline for applying GEVD and GPD to wind time series of limited length. The data analysis shows that, with reasonable choice of relevant parameters, GEVD and GPD give consistent estimates of the return winds. For GEVD, the base period should be chosen in accordance with the occurrence of the extreme wind......This study examines the various sources to the uncertainties in the application of two widely used extreme value distribution functions, the generalized extreme value distribution (GEVD) and the generalized Pareto distribution (GPD). The study is done through the analysis of measurements from...
Reconciling fault-tolerant distributed algorithms and real-time computing.
Moser, Heinrich; Schmid, Ulrich
We present generic transformations, which allow to translate classic fault-tolerant distributed algorithms and their correctness proofs into a real-time distributed computing model (and vice versa). Owing to the non-zero-time, non-preemptible state transitions employed in our real-time model, scheduling and queuing effects (which are inherently abstracted away in classic zero step-time models, sometimes leading to overly optimistic time complexity results) can be accurately modeled. Our results thus make fault-tolerant distributed algorithms amenable to a sound real-time analysis, without sacrificing the wealth of algorithms and correctness proofs established in classic distributed computing research. By means of an example, we demonstrate that real-time algorithms generated by transforming classic algorithms can be competitive even w.r.t. optimal real-time algorithms, despite their comparatively simple real-time analysis.
A Theory for the Initial Allocating of Real Time Tasks in Distributed Systems
Institute of Scientific and Technical Information of China (English)
鄢勇; 金灿明
1992-01-01
Referring to a set of real time tasks with arriving time,executing time and deadline,this paper discusses the problem of polynomial time initial-allocating approximation algorithms in a distributed system and five new results are gained which provide a theory for the designing of initial-allocating algorithms of real time tasks.
Energy Technology Data Exchange (ETDEWEB)
Takahashi, K.; Nakamura, Y. [Nagasaki Univ. (Japan)] Shimizu, Y. [Kumagai Gumi Co. Ltd., Tokyo (Japan)
1998-10-20
Two years after the above-titled earthquake, an examination was performed on inhabitants in the temporary dwelling houses in Kobe, center of the calamity, and problems caused by a long stay there were clarified together with a grasp of the evolving problems by comparing the result of survey carried out immediately after the disaster. The number of such temporary dwelling houses amounted to 29,128 within Kobe City and 3,168 outside of the city. According to the room arrangement, they were either one f 4 types : 2-rooms with a kitchen, 1 room with a kitchen, dormitory and those specifically for aged persons. There were 59,449 applications at the first offer of 2,702 houses. The priority of their assignments and so on are explained. As for the housing structure, numerous complaints concerned with the room temperature, noise and so forth. As for the living environment, lack of nearby commodity shop, omission of transportation access, ill drainage of the housing sites were pointed out and the matters of demand to the local authorities included the installation of mail post and street lights. As for the health management, insomnia, stiff shoulder, lumbago and other bad physical conditions were revealed. The financial difficulty and the high house rent were obstacles to migrate to other places. The prolonged temporary lives worsened the apprehension of dwellers for the earthquake, typhoon, fire and alike. Some features for the calamity are described in comparison with the result of survey on those who were compelled to live under similar conditions by the eruption of Mr. Fugen. 6 refs., 13 figs., 15 tabs.
Real-Time Distributed Embedded Oscillator Operating Frequency Monitoring
Pollock, Julie; Oliver, Brett; Brickner, Christopher
2012-01-01
A document discusses the utilization of embedded clocks inside of operating network data links as an auxiliary clock source to satisfy local oscillator monitoring requirements. Modem network interfaces, typically serial network links, often contain embedded clocking information of very tight precision to recover data from the link. This embedded clocking data can be utilized by the receiving device to monitor the local oscillator for tolerance to required specifications, often important in high-integrity fault-tolerant applications. A device can utilize a received embedded clock to determine if the local or the remote device is out of tolerance by using a single link. The local device can determine if it is failing, assuming a single fault model, with two or more active links. Network fabric components, containing many operational links, can potentially determine faulty remote or local devices in the presence of multiple faults. Two methods of implementation are described. In one method, a recovered clock can be directly used to monitor the local clock as a direct replacement of an external local oscillator. This scheme is consistent with a general clock monitoring function whereby clock sources are clocking two counters and compared over a fixed interval of time. In another method, overflow/underflow conditions can be used to detect clock relationships for monitoring. These network interfaces often provide clock compensation circuitry to allow data to be transferred from the received (network) clock domain to the internal clock domain. This circuit could be modified to detect overflow/underflow conditions of the buffering required and report a fast or slow receive clock, respectively.
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.
The waiting time distribution as a graphical approach to epidemiologic measures of drug utilization
DEFF Research Database (Denmark)
Hallas, J; Gaist, D; Bjerrum, L
1997-01-01
of the window. After a few months, the graph will be dominated by new, incident users. As examples, we present waiting time distributions for insulin, ulcer drugs, systemic corticosteroids, antidepressants, and disulfiram. Appropriately analyzed and interpreted, the waiting time distributions can provide...
Quasi Serializable Concurrency Control in Distributed Real-Time Database Systems
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
This paper formally defines and analyses the new notion of correctness called quasi serializability, and then outlines corresponding concurrency control protocol QDHP for distributed real-time databases. Finally, through a series of simulation studies, it shows that using the new concurrency control protocol the performance of distributed real-time databases can be much improved.
Just-in-Time Retail Distribution : A Systems Perspective on Cross-Docking
Buijs, Paul; Danhof, Hans W.; Wortmann, J.(Hans) C.
2016-01-01
Cross-docking is a just-in-time strategy for distribution logistics. It is aimed at reducing inventory levels and distribution lead times by creating a seamless flow of products from suppliers to customers. Prior supply chain literature has argued that creating such a seamless product flows requires
Just-in-Time Retail Distribution : A Systems Perspective on Cross-Docking
Buijs, Paul; Danhof, Hans W.; Wortmann, J.(Hans) C.
2016-01-01
Cross-docking is a just-in-time strategy for distribution logistics. It is aimed at reducing inventory levels and distribution lead times by creating a seamless flow of products from suppliers to customers. Prior supply chain literature has argued that creating such a seamless product flows requires
The distribution of first-passage times and durations in FOREX and future markets
Sazuka, Naoya; Inoue, Jun-ichi; Scalas, Enrico
2009-07-01
Possible distributions are discussed for intertrade durations and first-passage processes in financial markets. The view-point of renewal theory is assumed. In order to represent market data with relatively long durations, two types of distributions are used, namely a distribution derived from the Mittag-Leffler survival function and the Weibull distribution. For the Mittag-Leffler type distribution, the average waiting time (residual life time) is strongly dependent on the choice of a cut-off parameter tmax, whereas the results based on the Weibull distribution do not depend on such a cut-off. Therefore, a Weibull distribution is more convenient than a Mittag-Leffler type if one wishes to evaluate relevant statistics such as average waiting time in financial markets with long durations. On the other hand, we find that the Gini index is rather independent of the cut-off parameter. Based on the above considerations, we propose a good candidate for describing the distribution of first-passage time in a market: The Weibull distribution with a power-law tail. This distribution compensates the gap between theoretical and empirical results more efficiently than a simple Weibull distribution. It should be stressed that a Weibull distribution with a power-law tail is more flexible than the Mittag-Leffler distribution, which itself can be approximated by a Weibull distribution and a power-law. Indeed, the key point is that in the former case there is freedom of choice for the exponent of the power-law attached to the Weibull distribution, which can exceed 1 in order to reproduce decays faster than possible with a Mittag-Leffler distribution. We also give a useful formula to determine an optimal crossover point minimizing the difference between the empirical average waiting time and the one predicted from renewal theory. Moreover, we discuss the limitation of our distributions by applying our distribution to the analysis of the BTP future and calculating the average waiting
Dwell fatigue in two Ti alloys: An integrated crystal plasticity and discrete dislocation study
Zheng, Zebang; Balint, Daniel S.; Dunne, Fionn P. E.
2016-11-01
It is a well known and important problem in the aircraft engine industry that alloy Ti-6242 shows a significant reduction in fatigue life, termed dwell debit, if a stress dwell is included in the fatigue cycle, whereas Ti-6246 does not; the mechanistic explanation for the differing dwell debit of these alloys has remained elusive for decades. In this work, crystal plasticity modelling has been utilised to extract the thermal activation energies for pinned dislocation escape for both Ti alloys based on independent experimental data. This then allows the markedly different cold creep responses of the two alloys to be captured accurately and demonstrates why the observed near-identical rate sensitivity under non-dwell loading is entirely consistent with the dwell behaviour. The activation energies determined are then utilised within a recently developed thermally-activated discrete dislocation plasticity model to predict the strain rate sensitivities of the two alloys associated with nano-indentation into basal and prism planes. It is shown that Ti-6242 experiences a strong crystallographic orientation-dependent rate sensitivity while Ti-6246 does not which is shown to agree with recently published independent measurements; the dependence of rate sensitivity on indentation slip plane is also well captured. The thermally-activated discrete dislocation plasticity model shows that the incorporation of a stress dwell in fatigue loading leads to remarkable stress redistribution from soft to hard grains in the classical cold dwell fatigue rogue grain combination in alloy Ti-6242, but that no such load shedding occurs in alloy Ti-6246. The key property controlling the behaviour is the time constant of the thermal activation process relative to that of the loading. This work provides the first mechanistic basis to explain why alloy Ti-6242 shows a dwell debit but Ti-6246 does not.
Radar signal analysis of ballistic missile with micro-motion based on time-frequency distribution
Wang, Jianming; Liu, Lihua; Yu, Hua
2015-12-01
The micro-motion of ballistic missile targets induces micro-Doppler modulation on the radar return signal, which is a unique feature for the warhead discrimination during flight. In order to extract the micro-Doppler feature of ballistic missile targets, time-frequency analysis is employed to process the micro-Doppler modulated time-varying radar signal. The images of time-frequency distribution (TFD) reveal the micro-Doppler modulation characteristic very well. However, there are many existing time-frequency analysis methods to generate the time-frequency distribution images, including the short-time Fourier transform (STFT), Wigner distribution (WD) and Cohen class distribution, etc. Under the background of ballistic missile defence, the paper aims at working out an effective time-frequency analysis method for ballistic missile warhead discrimination from the decoys.
DEFF Research Database (Denmark)
Wang, Qi
and DR resources, and upwardly trading in the TL real-time market, resulting in a proactive manner. The DL aggregator (DA) is dened to manage these small-scale and dispersed DGs and DRs. A methodology is proposed in this thesis for a proactive DISCO (PDISCO) to strategically trade with DAs...
Indoor air quality in typical temperate zone Australian dwellings
Molloy, S. B.; Cheng, M.; Galbally, I. E.; Keywood, M. D.; Lawson, S. J.; Powell, J. C.; Gillett, R.; Dunne, E.; Selleck, P. W.
2012-07-01
We report the results of a comprehensive study of indoor air quality in typical temperate zone Australian dwellings. Forty dwellings located over an 800 km2 area in the south-east of Melbourne with a range of ages, materials and structures representative of Australian dwellings were selected. A range of indoor air quality pollutants were sampled both inside and outside for one week each in Winter/Spring 2008 and Summer/Autumn 2009. Information was collected on house characteristics, the surrounding areas and occupant activities during the sampling. Weekly indoor averaged CO2 (536 ± 121 ppm), CO (0.3 ± 0.2 ppm), PM2.5 (8.4 ± 4.0 μg m-3), temperatures (21.2 ± 2.0 °C), water vapour mixing ratios (7.9 ± 1.3 g kg-1), benzene (1.3 ± 1.1 μg m-3), toluene (8.8 ± 7.9 μg m-3) and xylenes (6.2 ± 6.7 μg m-3) varied from 1.1 to approximately three times higher compared to the equivalent outdoors concentrations. Formaldehyde (12.2 ± 4.7 ppb), other carbonyls (7.9 ± 2.6 ppb) and total volatile organic compounds (181.1 ± 89.5 μg m-3) had indoor concentrations of factors between eight and 12 times higher compared to outdoor concentrations. Weekly averaged indoor ozone (0.7 ± 0.7 ppb), NO2 (8.4 ± 3.9 ppb) and PM10 (20.4 ± 8.1 μg m-3) were significantly lower than outdoors. Correlations and factor analysis showed the major influences on this indoor air quality were (a) dwelling age, whereby dwellings constructed in recent decades compared to older buildings were found to have increased concentrations of the highly elevated species formaldehyde, other carbonyls and total volatile organic compounds, and (b) combustion and cooking activities that increased the concentrations of multiple species including CO, CO2, NO2, H2O and particles. The indoor pollutant concentrations from this study were in general comparable with or lower than other Australian or overseas studies.
Design and Research of Distributed Real TimeSurveillance Control System
Institute of Scientific and Technical Information of China (English)
2015-01-01
Distributed real time surveillance control system is used especially in distributed computer measure and control system, mostly inwidely dispersed measure points without human surveillance. This paper describes theory、construction、control strategy, stabilityanalysis of distributed real time supervisory control and data acquisition system, implements distributed measure signals collectionand design of supervisory control system. The realization of virtual instrument based on VC＋＋ can accomplish measurementsignals acquisition, storage, display and analysis, also the result of surveillance control system is provided, and shows thefunctional powerful agility of virtual instrument based on VC＋＋.
Population and dwelling unit estimates from space.
Webster, C J
1996-05-01
"To increase the utility of satellite imagery as a source of cheap and current information for planning and managing cities some problems have to be resolved.... One answer is to adopt interpretation methods that use the increased information in a more detailed scene. This paper reports on attempts to measure the morphological patterns in an urban satellite scene and to use these for image interpretation. The interpretation task addressed is the estimation of residential dwelling units from the patterns discernible in high resolution satellite images of cities. The practical results include dwelling estimates that can be aggregated to any geographical unit of analysis, population estimates for cities and a dwelling density surface that can be categorised into any number of residential land-use classes."
Building XenoBuntu Linux Distribution for Teaching and Prototyping Real-Time Operating Systems
Slim BEN SAOUD; Ahmed BEN ACHBALLAH; Litayem, Nabil
2011-01-01
This paper describes the realization of a new Linux distribution based on Ubuntu Linux and Xenomai Real-Time framework. This realization is motivated by the eminent need of real-time systems in modern computer science courses. The majority of the technical choices are made after qualitative comparison. The main goal of this distribution is to offer standard Operating Systems (OS) that include Xenomai infrastructure and the essential tools to begin hard real-time application development inside...
Kosov, Daniel S.
2017-02-01
On the elementary level, electronic current consists of individual electron tunnelling events that are separated by random time intervals. The waiting time distribution is a probability to observe the electron transfer in the detector electrode at time t +τ given that an electron was detected in the same electrode at an earlier time t. We study waiting time distribution for quantum transport in a vibrating molecular junction. By treating the electron-vibration interaction exactly and molecule-electrode coupling perturbatively, we obtain the master equation and compute the distribution of waiting times for electron transport. The details of waiting time distributions are used to elucidate microscopic mechanism of electron transport and the role of electron-vibration interactions. We find that as nonequilibrium develops in the molecular junction, the skewness and dispersion of the waiting time distribution experience stepwise drops with the increase of the electric current. These steps are associated with the excitations of vibrational states by tunnelling electrons. In the strong electron-vibration coupling regime, the dispersion decrease dominates over all other changes in the waiting time distribution as the molecular junction departs far away from the equilibrium.
Damage Detection Based on Cross-Term Extraction from Bilinear Time-Frequency Distributions
Directory of Open Access Journals (Sweden)
Ma Yuchao
2014-01-01
Full Text Available Abundant damage information is implicated in the bilinear time-frequency distribution of structural dynamic signals, which could provide effective support for structural damage identification. Signal time-frequency analysis methods are reviewed, and the characters of linear time-frequency distribution and bilinear time-frequency distribution typically represented by the Wigner-Ville distribution are compared. The existence of the cross-term and its application in structural damage detection are demonstrated. A method of extracting the dominant term is proposed, which combines the short-time Fourier spectrum and Wigner-Ville distribution; then two-dimensional time-frequency transformation matrix is constructed and the complete cross-term is extracted finally. The distribution character of which could be applied to the structural damage identification. Through theoretical analysis, model experiment and numerical simulation of the girder structure, the change rate of cross-term amplitude is validated to identify the damage location and degree. The effectiveness of the cross-term of bilinear time-frequency distribution for damage detection is confirmed and the analytical method of damage identification used in structural engineering is available.
Timing System Solution for MedAustron; Real-time Event and Data Distribution Network
Štefanič, R; Dedič, J; Gutleber, J; Moser, R
2011-01-01
MedAustron is an ion beam research and therapy centre under construction in Wiener Neustadt, Austria. The facility features a synchrotron particle accelerator for light ions. The timing system for this class of accelerators has been developed in close collaboration between MedAustron and Cosylab. Mitigating economical and technological risks, we have chosen a proven, widely used Micro Research Finland (MRF) timing equipment and redesigned its FPGA firmware, extending its high-logic services above transport layer, as required by machine specifics. We obtained a generic real-time broadcast network for coordinating actions of a compact, pulse-to-pulse modulation based particle accelerator. High-level services include support for virtual accelerators and a rich selection of event response mechanisms. The system uses a combination of a real-time link for downstream events and a non-real-time link for upstream messaging and non time-critical communication. It comes with National Instruments LabVI...
The effect of distributed time-delays on the synchronization of neuronal networks
Kachhvah, Ajay Deep
2017-01-01
Here we investigate the synchronization of networks of FitzHugh-Nagumo neurons coupled in scale-free, small-world and random topologies, in the presence of distributed time delays in the coupling of neurons. We explore how the synchronization transition is affected when the time delays in the interactions between pairs of interacting neurons are non-uniform. We find that the presence of distributed time-delays does not change the behavior of the synchronization transition significantly, vis-a-vis networks with constant time-delay, where the value of the constant time-delay is the mean of the distributed delays. We also notice that a normal distribution of delays gives rise to a transition at marginally lower coupling strengths, vis-a-vis uniformly distributed delays. These trends hold across classes of networks and for varying standard deviations of the delay distribution, indicating the generality of these results. So we conclude that distributed delays, which may be typically expected in real-world situations, do not have a notable effect on synchronization. This allows results obtained with constant delays to remain relevant even in the case of randomly distributed delays.
Energy Technology Data Exchange (ETDEWEB)
Kumar, Syam [Malabar Cancer Centre, Kannur, Kerala (India); Sitha [University of Calicut, Calicut, Kerala (India)
2015-06-15
Purpose: Determination of source dwell positions of HDR brachytherapy using 2D 729 ion chamber array Methods: Nucletron microselectron HDR and PTW 2D array were used for the study. Different dwell positions were assigned in the HDR machine. Rigid interstitial needles and vaginal applicator were positioned on the 2D array. The 2D array was exposed for this programmed dwell positions. The positional accuracy of the source was analyzed after the irradiation of the 2D array. This was repeated for different dwell positions. Different test plans were transferred from the Oncentra planning system and irradiated with the same applicator position on the 2D array. The results were analyzed using the in house developed excel program. Results: Assigned dwell positions versus corresponding detector response were analyzed. The results show very good agreement with the film measurements. No significant variation found between the planned and measured dwell positions. Average dose response with 2D array between the planned and nearby dwell positions was found to be 0.0804 Gy for vaginal cylinder applicator and 0.1234 Gy for interstitial rigid needles. Standard deviation between the doses for all the measured dwell positions for interstitial rigid needle for 1 cm spaced positions were found to be 0.33 and 0.37 for 2cm spaced dwell positions. For intracavitory vaginal applicator this was found to be 0.21 for 1 cm spaced dwell positions and 0.06 for 2cm spaced dwell positions. Intracavitory test plans reproduced on the 2D array with the same applicator positions shows the ideal dose distribution with the TPS planned. Conclusion: 2D array is a good tool for determining the dwell position of HDR brachytherapy. With the in-house developed program in excel it is easy and accurate. The traditional way with film analysis can be replaced by this method, as the films will be more costly.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The time-varying autoregressive (TVAR) modeling of a non-stationary signal is studied. In the proposed method, time-varying parametric identification of a non-stationary signal can be translated into a linear time-invariant problem by introducing a set of basic functions. Then, the parameters are estimated by using a recursive least square algorithm with a forgetting factor and an adaptive time-frequency distribution is achieved. The simulation results show that the proposed approach is superior to the short-time Fourier transform and Wigner distribution. And finally, the proposed method is applied to the fault diagnosis of a bearing, and the experiment result shows that the proposed method is effective in feature extraction.
DEFF Research Database (Denmark)
Kristensen, C.H.
a higher confidence in the system behaviour. We have proposed a combination of formal methods and supplemental fault-detection techniques which we call the Complementary Run-Time Evaluation Model. The basic idea in this model is to use the means of verification given by formal methods, to prove......This thesis advocates a formal approach to run-time evaluation of real-time behaviour in distributed process sontrol systems, motivated by a growing interest in applying the increasingly popular formal methods in the application area of distributed process control systems. We propose to evaluate...... the various models underlaying every formal method by declaring the design assumptions as a number of features or constraints, stated in the formal specification of system requirements, to be evaluated at run-time. It is assumed that if these constraints are ful-filled at run-time then it is fair to have...
Institute of Scientific and Technical Information of China (English)
SHEN Yan
2005-01-01
@@ With developments of technology of computer and network, researching on distributed measurement system becomes one of the hot problems in the field of automatic test. However, existing resolutions to distributed measurement system still have great limit,e.g. intelligence, self-adaptivity, collaboration, system load balance and integer view, and their capabilities need to be enhanced. Based on two key projects, this paper studies on collaboration mechanism and real-time of communication platform in distributed measurement system comprehensively and systematically.
Berezhkovskii, Alexander M.; Hummer, Gerhard; Bezrukov, Sergey M.
2006-07-01
We study the distribution of direct translocation times for particles passing through membrane channels connecting two reservoirs. The direct translocation time is a conditional first-passage time defined as the residence time of the particle in the channel while passing to the other side of the membrane directly, i.e., without returning to the reservoir from which it entered. We show that the distributions of direct translocation times are identical for translocation in both directions, independent of any asymmetry in the potential across the channel and, hence, the translocation probabilities.
Pongthanaracht, Natsalil; Yanarojana, Somchai; Pinthong, Darawan; Unchern, Supeenun; Thithapandha, Amnuay; Assantachai, Prasert; Supavilai, Porntip
2017-01-01
To study the association of the butyrylcholinesterase K variant (BChE-K) and the plasma BChE activity with mild cognitive impairment (MCI) in Thai community-dwelling patients. One hundred patients diagnosed with MCI and 100 control subjects were recruited from the community-dwelling setting in Bangkok, Thailand. The genotype and allele distributions of the BChE-K were determined by polymerase chain reaction and subsequent DNA sequencing. The BChE activity was measured in plasma according to the Ellman's method. The BChE-K allele frequencies in the Thai community-dwelling patients were in accordance with other ethnics. The BChE-K allele frequency in the control subjects (12%) was higher than that of MCI patients (5.5%), suggesting a protective role of BChE-K for MCI in the Thai community-dwelling patients. The BChE-K homozygotes were significantly associated with lower BChE activity. Our results suggested that the BChE-K may be implicated as a protective factor for MCI in the Thai community-dwelling patients, although a further study with a large sample size is warranted to confirm this.
Directory of Open Access Journals (Sweden)
M. C. Roa-García
2010-08-01
Full Text Available We present a new modeling approach analyzing and predicting the Transit Time Distribution (TTD and the Response Time Distribution (RTD from hourly to annual time scales as two distinct hydrological processes. The model integrates Isotope Hydrograph Separation (IHS and the Instantaneous Unit Hydrograph (IUH approach as a tool to provide a more realistic description of transit and response time of water in catchments. Individual event simulations and parameterizations were combined with long-term baseflow simulation and parameterizations; this provides a comprehensive picture of the catchment response for a long time span for the hydraulic and isotopic processes. The proposed method was tested in three Andean headwater catchments to compare the effects of land use on hydrological response and solute transport. Results show that the characteristics of events and antecedent conditions have a significant influence on TTD and RTD, but in general the RTD of the grassland dominated catchment is concentrated in the shorter time spans and has a higher cumulative TTD, while the forest dominated catchment has a relatively higher response distribution and lower cumulative TTD. The catchment where wetlands concentrate shows a flashier response, but wetlands also appear to prolong transit time.
Directory of Open Access Journals (Sweden)
M. C. Roa-García
2010-01-01
Full Text Available We present a new modeling approach analyzing and predicting the Transit Time Distribution (TTD and the Response Time Distribution (RTD from hourly to annual time scales as two distinct hydrological processes. The model integrates Isotope Hydrograph Separation (IHS and the Instantaneous Unit Hydrograph (IUH approach as a tool to provide a more realistic description of transit and response time of water in catchments. Individual event simulations and parameterizations were combined with long-term baseflow simulation and parameterizations to provide a comprehensive picture of the catchment response for a long time span for the hydraulic and isotopic processes. The proposed method was tested in three Andean headwater catchments to compare the effects of land use on hydrological response and solute transport. Results show that the characteristics of events and antecedent conditions have a significant influence on TTD and RTD, but in general the RTD of the grassland dominated catchment is concentrated in the shorter time spans and has a higher cumulative TTD, while the forest dominated catchment has a relatively longer response distribution and lower cumulative TTD. The catchment where wetlands concentrate shows a flashier response, but wetlands also appear to contribute to prolong transit time.
DEFF Research Database (Denmark)
Li, Chendan; Schaltz, Erik; Quintero, Juan Carlos Vasquez
2016-01-01
The predictable increasing adoption of EV by residential users imposes the necessity of Electric Vehicle charging coordination, in order to charge effectively while minimizing the impact on the grid. In this paper, a two-stage distributed coordination algorithm for electric vehicle charging...... activity based on the real-time price, while meeting the requirement of technical constraints of the distribution system....
RTnet: a distributed real-time protocol for broadcast-capable networks
Hanssen, Ferdy; Jansen, Pierre G.; Scholten, Hans; Mullender, Sape
2005-01-01
We present an overview of a distributed real-time network protocol, to be used on fully-connected local area networks with a broadcast capability. It supports on-the-fly addition and removal of network nodes, resource-lavish and resource-lean devices, streaming real-time and regular non-real-time tr
Design Optimization of Cyber-Physical Distributed Systems using IEEE Time-sensitive Networks (TSN)
DEFF Research Database (Denmark)
Pop, Paul; Lander Raagaard, Michael; Craciunas, Silviu S.
2016-01-01
In this paper we are interested in safety-critical real-time applications implemented on distributed architectures supporting the Time-SensitiveNetworking (TSN) standard. The ongoing standardization of TSN is an IEEE effort to bring deterministic real-time capabilities into the IEEE 802.1 Ethernet...
Müller, Markus; Meztler, Holger; Glatt, Anna; Sierra, Carlos
2016-04-01
We present theoretical methods to compute dynamic residence and transit time distributions for non-autonomous systems of pools governed by coupled nonlinear differential equations. Although transit time and age distributions have been used to describe reservoir models for a long time, a closer look to their assumptions reveals two major restrictions of generality in previous studies. First, the systems are assumed to be in equilibrium; and second, the equations under consideration are assumed to be linear. While both these assumptions greatly ease the computation and interpretation of transit time and age distributions they are not applicable to a wide range of problems. Moreover, the transfer of previous results learned from linear systems in steady state to the more complex nonlinear non-autonomous systems that do not even need to have equilibria, can be dangerously misleading. Fortunately the topic of time dependent age and transit time distributions has received some attention recently in hydrology, we aim to compute these distributions for systems of multiple reservoirs. We will discuss how storage selection functions can augment the information represented in an ODE system describing a system of reservoirs. We will present analytical and numerical algorithms and a Monte Carlo simulator to compute solutions for system transit time and age distributions for system-wide storage selection functions including the most simple, but important case of well mixed pools.
A Real-Time Fault Management Software System for Distributed Environments Project
National Aeronautics and Space Administration — DyMA-FM (Dynamic Multivariate Assessment for Fault Management) is a software architecture for real-time fault management. Designed to run in a distributed...
Distributed finite-time containment control for double-integrator multiagent systems.
Wang, Xiangyu; Li, Shihua; Shi, Peng
2014-09-01
In this paper, the distributed finite-time containment control problem for double-integrator multiagent systems with multiple leaders and external disturbances is discussed. In the presence of multiple dynamic leaders, by utilizing the homogeneous control technique, a distributed finite-time observer is developed for the followers to estimate the weighted average of the leaders' velocities at first. Then, based on the estimates and the generalized adding a power integrator approach, distributed finite-time containment control algorithms are designed to guarantee that the states of the followers converge to the dynamic convex hull spanned by those of the leaders in finite time. Moreover, as a special case of multiple dynamic leaders with zero velocities, the proposed containment control algorithms also work for the case of multiple stationary leaders without using the distributed observer. Simulations demonstrate the effectiveness of the proposed control algorithms.
The effect of distributed time-delays on the synchronization of neuronal networks
Kachhvah, Ajay Deep
2016-01-01
Here we investigate the synchronization of networks of FitzHugh-Nagumo neurons coupled in scale-free, small-world and random topologies, in the presence of distributed time delays in the coupling of neurons. We explore how the synchronization transition is affected when the time delays in the interactions between pairs of interacting neurons are non-uniform. We find that the presence of distributed time-delays does not change the behavior of the synchronization transition significantly, vis-a-vis networks with constant time-delay, where the value of the constant time-delay is the mean of the distributed delays. We also notice that a normal distribution of delays gives rise to a transition at marginally lower coupling strengths, vis-a-vis uniformly distributed delays. These trends hold across classes of networks and for varying standard deviations of the delay distribution, indicating the generality of these results. So we conclude that distributed delays, which may be typically expected in real-world situatio...
Two phase residence time distribution in a modified twin screw extruder
1999-01-01
Biomass fractionation is performed with a modified Clextral twin-screw extruder used as a thermo-mechano-chemical reactor. This new process is firstly analyzed. Visual observations, residence time distributions, and global mass balances are used to obtain information about the process phenomena and their coupling. Residence time distributions (RTD) classical models are adopted to represent the experimental plots. The influence of continuous and discrete process parameters upon the RTD of the ...
517 DWELLING DENSITY VARIABILITY ACROSS GOVERNMENT ...
African Journals Online (AJOL)
Osondu
approach. This finding was supported by the results of a chi-square test which found that, at 95% ... of life. Key words: dwelling density, home spaces, housing units, multifamily apartments ... single interior space is typically referred to as a room ...
25 CFR 700.53 - Dwelling, replacement.
2010-04-01
... § 700.55. (b) May include existing dwellings for resale, new construction, modular homes, mobile homes... person if, after he receives a replacement housing payment and any available housing assistance payments... supplemental income payments received from public agencies. If the person's monthly income pattern is...
Modeling solute transport in distribution networks with variable demand and time step sizes.
Energy Technology Data Exchange (ETDEWEB)
Peyton, Chad E.; Bilisoly, Roger Lee; Buchberger, Steven G. (University of Cincinnati, Cincinnati, OH); McKenna, Sean Andrew; Yarrington, Lane
2004-06-01
The effect of variable demands at short time scales on the transport of a solute through a water distribution network has not previously been studied. We simulate flow and transport in a small water distribution network using EPANET to explore the effect of variable demand on solute transport across a range of hydraulic time step scales from 1 minute to 2 hours. We show that variable demands at short time scales can have the following effects: smoothing of a pulse of tracer injected into a distribution network and increasing the variability of both the transport pathway and transport timing through the network. Variable demands are simulated for these different time step sizes using a previously developed Poisson rectangular pulse (PRP) demand generator that considers demand at a node to be a combination of exponentially distributed arrival times with log-normally distributed intensities and durations. Solute is introduced at a tank and at three different network nodes and concentrations are modeled through the system using the Lagrangian transport scheme within EPANET. The transport equations within EPANET assume perfect mixing of the solute within a parcel of water and therefore physical dispersion cannot occur. However, variation in demands along the solute transport path contribute to both removal and distortion of the injected pulse. The model performance measures examined are the distribution of the Reynolds number, the variation in the center of mass of the solute across time, and the transport path and timing of the solute through the network. Variation in all three performance measures is greatest at the shortest time step sizes. As the scale of the time step increases, the variability in these performance measures decreases. The largest time steps produce results that are inconsistent with the results produced by the smaller time steps.
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.
On a link between a species survival time in an evolution model and the Bessel distributions
Guiol, Herve; Schinazi, Rinaldo B
2011-01-01
We consider a stochastic model for species evolution. A new species is born at rate lambda and a species dies at rate mu. A random number, sampled from a given distribution F, is associated with each new species at the time of birth. Every time there is a death event, the species that is killed is the one with the smallest fitness. We consider the (random) survival time of a species with a given fitness f. We show that the survival time distribution depends crucially on whether ff_c where f_c is a critical fitness that is computed explicitly.
Directory of Open Access Journals (Sweden)
Young S. Shin
1993-01-01
Full Text Available Machinery operating in a nonstationary mode generates a signature that at each instant of time has a distinct frequency. A Time-frequency domain representation is needed to characterize such a signature. Pseudo Wigner–Ville distribution is ideally suited for portraying a nonstationary signal in the time-frequency domain and is carried out by adapting the fast Fourier transform algorithm. The important parameters affecting the pseudo Wigner–Ville distribution are discussed and sensitivity analyses are also performed. Practical examples of an actual transient signal are used to illustrate its dynamic features jointly in time and frequency.
Energy Technology Data Exchange (ETDEWEB)
Gotzig, B. [Laboratoire d`Electrotechnique de Grenoble (France)]|[Schneider Electric S.A., Grenoble (France); Hadjsaid, N.; Feuillet, R. [Laboratoire d`Electrotechnique de Grenoble (France); Jeannot, R. [Schneider Electric S.A., Grenoble (France)
1998-12-31
Optimization of large scale distribution systems on a real time base requires computationally efficient algorithms. In this paper a fast general branch exchange algorithm is proposed. Depending on the objective function which is optimized, both the line loss reduction in the normal state and the restoration of de-energized loads can be carried out. Tests were carried out on a real large scale distribution network. They demonstrate that the method is fast and that it can be used in distribution management systems on real time base. (author)
Distributive Network Utility Maximization (NUM) over Time-Varying Fading Channels
Chen, Junting; Lau, Vincent K N
2011-01-01
Distributed network utility maximization (NUM) has received an increasing intensity of interest over the past few years. Distributed solutions (e.g., the primal-dual gradient method) have been intensively investigated under fading channels. As such distributed solutions involve iterative updating and explicit message passing, it is unrealistic to assume that the wireless channel remains unchanged during the iterations. Unfortunately, the behavior of those distributed solutions under time-varying channels is in general unknown. In this paper, we shall investigate the convergence behavior and tracking errors of the iterative primal-dual scaled gradient algorithm (PDSGA) with dynamic scaling matrices (DSC) for solving distributive NUM problems under time-varying fading channels. We shall also study a specific application example, namely the multi-commodity flow control and multi-carrier power allocation problem in multi-hop ad hoc networks. Our analysis shows that the PDSGA converges to a limit region rather tha...
How Do Output Growth Rate Distributions Look Like? Some Time-Series Evidence on OECD Countries
Fagiolo, G; Roventini, A; Fagiolo, Giorgio; Napoletano, Mauro; Roventini, Andrea
2006-01-01
This paper investigates the statistical properties of within-country GDP and industrial production (IP) growth rate distributions. Many empirical contributions have recently pointed out that cross-section growth rates of firms, industries and countries all follow Laplace distributions. In this work, we test whether also within-country, time-series GDP and IP growth rates can be approximated by tent-shaped distributions. We fit output growth rates with the exponential-power (Subbotin) family of densities, which includes as particular cases both the Gaussian and the Laplace distributions. We find that, for a large number of OECD countries including the U.S., both GDP and IP growth rates are Laplace distributed. Moreover, we show that fat-tailed distributions robustly emerge even after controlling for outliers, autocorrelation and heteroscedasticity.
A double hit model for the distribution of time to AIDS onset
Chillale, Nagaraja Rao
2013-09-01
Incubation time is a key epidemiologic descriptor of an infectious disease. In the case of HIV infection this is a random variable and is probably the longest one. The probability distribution of incubation time is the major determinant of the relation between the incidences of HIV infection and its manifestation to Aids. This is also one of the key factors used for accurate estimation of AIDS incidence in a region. The present article i) briefly reviews the work done, points out uncertainties in estimation of AIDS onset time and stresses the need for its precise estimation, ii) highlights some of the modelling features of onset distribution including immune failure mechanism, and iii) proposes a 'Double Hit' model for the distribution of time to AIDS onset in the cases of (a) independent and (b) dependent time variables of the two markers and examined the applicability of a few standard probability models.
Cumulative Interarrival Time Distributions of Freeway Entrance Ramp Traffic for Traffic Simulations
Directory of Open Access Journals (Sweden)
Erdinç Öner
2013-02-01
Full Text Available Cumulative interarrival time (IAT distributions for signalized and non-signalized freeway entrance ramps were developed to be used in digital computer traffic simulation models. The data from four different non-signalized entrance ramps (three ramps with a single lane, one ramp with two lanes and two different signalized entrance ramps (both with a single lane were used for developing the cumulative IAT distributions. The cumulative IAT distributions for the signalized and non-signalized entrance ramps were compared with each other and with the cumulative IAT distributions of the lanes for freeways. The comparative results showed that the cumulative IAT distributions for non-signalized entrance ramps are very close to the leftmost lane of a 3-lane freeway where the maximum absolute difference between the cumulative IAT distribution of the leftmost lane of a 3-lane freeway and the entrance ramps cumulative IAT distribution was 3%. The cumulative IAT distribution for the signalized entrance ramps was found to be different from the non-signalized entrance ramp cumulative IAT distribution. The approximated cumulative IAT distributions for signalized and non-signalized entrance ramp traffic for any hourly traffic volume from a few vehicles/hour up to 2,500 vehicles/hour can be obtained at http://www.ohio.edu/orite/research/uitds.cfm.
Challenges in reducing the computational time of QSTS simulations for distribution system analysis.
Energy Technology Data Exchange (ETDEWEB)
Deboever, Jeremiah [Georgia Inst. of Technology, Atlanta, GA (United States); Zhang, Xiaochen [Georgia Inst. of Technology, Atlanta, GA (United States); Reno, Matthew J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broderick, Robert Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grijalva, Santiago [Georgia Inst. of Technology, Atlanta, GA (United States); Therrien, Francis [CME International T& D, St. Bruno, QC (Canada)
2017-06-01
The rapid increase in penetration of distributed energy resources on the electric power distribution system has created a need for more comprehensive interconnection modelling and impact analysis. Unlike conventional scenario - based studies , quasi - static time - series (QSTS) simulation s can realistically model time - dependent voltage controllers and the diversity of potential impacts that can occur at different times of year . However, to accurately model a distribution system with all its controllable devices, a yearlong simulation at 1 - second resolution is often required , which could take conventional computers a computational time of 10 to 120 hours when an actual unbalanced distribution feeder is modeled . This computational burden is a clear l imitation to the adoption of QSTS simulation s in interconnection studies and for determining optimal control solutions for utility operations . Our ongoing research to improve the speed of QSTS simulation has revealed many unique aspects of distribution system modelling and sequential power flow analysis that make fast QSTS a very difficult problem to solve. In this report , the most relevant challenges in reducing the computational time of QSTS simulations are presented: number of power flows to solve, circuit complexity, time dependence between time steps, multiple valid power flow solutions, controllable element interactions, and extensive accurate simulation analysis.
Institute of Scientific and Technical Information of China (English)
王伟; 孙会君; 吴建军
2015-01-01
The assumption widely used in the user equilibrium model for stochastic network was that the probability distributions of the travel time were known explicitly by travelers. However, this distribution may be unavailable in reality. By relaxing the restrictive assumption, a robust user equilibrium model based on cumulative prospect theory under distribution-free travel time was presented. In the absence of the cumulative distribution function of the travel time, the exact cumulative prospect value (CPV) for each route cannot be obtained. However, the upper and lower bounds on the CPV can be calculated by probability inequalities. Travelers were assumed to choose the routes with the best worst-case CPVs. The proposed model was formulated as a variational inequality problem and solved via a heuristic solution algorithm. A numerical example was also provided to illustrate the application of the proposed model and the efficiency of the solution algorithm.
Baghfalaki, T; Ganjali, M; Hashemi, R
2014-01-01
Distributional assumptions of most of the existing methods for joint modeling of longitudinal measurements and time-to-event data cannot allow incorporation of outlier robustness. In this article, we develop and implement a joint modeling of longitudinal and time-to-event data using some powerful distributions for robust analyzing that are known as normal/independent distributions. These distributions include univariate and multivariate versions of the Student's t, the slash, and the contaminated normal distributions. The proposed model implements a linear mixed effects model under a normal/independent distribution assumption for both random effects and residuals of the longitudinal process. For the time-to-event process a parametric proportional hazard model with a Weibull baseline hazard is used. Also, a Bayesian approach using the Markov-chain Monte Carlo method is adopted for parameter estimation. Some simulation studies are performed to investigate the performance of the proposed method under presence and absence of outliers. Also, the proposed methods are applied for analyzing a real AIDS clinical trial, with the aim of comparing the efficiency and safety of two antiretroviral drugs, where CD4 count measurements are gathered as longitudinal outcomes. In these data, time to death or dropout is considered as the interesting time-to-event outcome variable. Different model structures are developed for analyzing these data sets, where model selection is performed by the deviance information criterion (DIC), expected Akaike information criterion (EAIC), and expected Bayesian information criterion (EBIC).
Sound classification of dwellings in the Nordic countries
DEFF Research Database (Denmark)
Rindel, Jens Holger; Turunen-Rise, Iiris
1997-01-01
A draft standard INSTA 122:1997 on sound classification of dwellings is for voting as a common national standard in the Nordic countries (Denmark, Norway, Sweden, Finland, Iceland) and in Estonia. The draft standard specifies a sound classification system with four classes A, B, C and D, where...... class C is proposed as the future minimum requirements for new dwellings. The classes B and A define criteria for dwellings with improved or very good acoustic conditions, whereas class D may be used for older, renovated dwellings in which the acoustic quality level of a new dwelling cannot reasonably...
Waiting time distribution revealing the internal spin dynamics in a double quantum dot
Ptaszyński, Krzysztof
2017-07-01
Waiting time distribution and the zero-frequency full counting statistics of unidirectional electron transport through a double quantum dot molecule attached to spin-polarized leads are analyzed using the quantum master equation. The waiting time distribution exhibits a nontrivial dependence on the value of the exchange coupling between the dots and the gradient of the applied magnetic field, which reveals the oscillations between the spin states of the molecule. The zero-frequency full counting statistics, on the other hand, is independent of the aforementioned quantities, thus giving no insight into the internal dynamics. The fact that the waiting time distribution and the zero-frequency full counting statistics give a nonequivalent information is associated with two factors. Firstly, it can be explained by the sensitivity to different timescales of the dynamics of the system. Secondly, it is associated with the presence of the correlation between subsequent waiting times, which makes the renewal theory, relating the full counting statistics and the waiting time distribution, no longer applicable. The study highlights the particular usefulness of the waiting time distribution for the analysis of the internal dynamics of mesoscopic systems.
The origin and non-universality of the earthquake inter-event time distribution
Touati, S.; Naylor, M.; Main, I. G.
2009-04-01
Understanding the form and origin of the earthquake inter-event time distribution is vital for both the advancement of seismic hazard assessment models and the development of physically-based models of earthquake dynamics. Many authors have modelled regional earthquake inter-event times using a gamma distribution, whereby data collapse occurs under a simple rescaling of the data from different regions or time periods. We use earthquake data and simulations to present a new understanding of the form of the earthquake inter-event time distribution as essentially bimodal, and a physically-motivated explanation for its origin in terms of the interaction of separate aftershock sequences within the earthquake time series. Our insight into the origin of the bimodality is through stochastic simulations of the Epidemic-Type Aftershock Sequences (ETAS) model, a point process model based on well-known empirical laws of seismicity, in which we are able to keep track of the triggering "family" structure in the catalogue unlike with real seismicity. We explain the variation of the distribution shape with region size and show that it is not universal under rescaling by the mean event rate. The power-law segment in the gamma distribution usually used to model inter-earthquake times arises under some conditions as a crossover between the two peaks; the previous results supporting universality can be explained by strong data selection criteria in the form of a requirement for short-term stationarity in the event rate.
Akimoto, Takuma; Yamamoto, Eiji
2016-12-01
Local diffusion coefficients in disordered systems such as spin glass systems and living cells are highly heterogeneous and may change over time. Such a time-dependent and spatially heterogeneous environment results in irreproducibility of single-particle-tracking measurements. Irreproducibility of time-averaged observables has been theoretically studied in the context of weak ergodicity breaking in stochastic processes. Here, we provide rigorous descriptions of equilibrium and non-equilibrium diffusion processes for the annealed transit time model, which is a heterogeneous diffusion model in living cells. We give analytical solutions for the mean square displacement (MSD) and the relative standard deviation of the time-averaged MSD for equilibrium and non-equilibrium situations. We find that the time-averaged MSD grows linearly with time and that the time-averaged diffusion coefficients are intrinsically random (irreproducible) even in the long-time measurements in non-equilibrium situations. Furthermore, the distribution of the time-averaged diffusion coefficients converges to a universal distribution in the sense that it does not depend on initial conditions. Our findings pave the way for a theoretical understanding of distributional behavior of the time-averaged diffusion coefficients in disordered systems.
Part-time wage-gap in Germany: Evidence across the wage distribution
Tõnurist, P.; Pavlopoulos, D.
2013-01-01
This paper uses insights from labour-market segmentation theory to investigate the wage differences between part-time and full-time workers in Germany at different parts of the wage distribution. This is accomplished with the use of a quintile regression and panel data from the SOEP (1991-2008). To
Relaxation Time of the Particle Beam with an Anisotropic Velocity Distribution
Directory of Open Access Journals (Sweden)
V.P. Vechirka
2012-11-01
Full Text Available The computer experiment for study of the relaxation time of the beam particles with an anisotropic velocity distribution is performed by the molecular dynamics. Obtained results agree with the characteristic times of thermal relaxation in plasma for the electronic coolers in modern storage rings.
The time distribution of aftershock magnitudes, fault geometry and aftershock prediction
Bhattacharya, Pathikrit; Chakrabarti, B K
2009-01-01
We have analyzed, for the first time, the time cumulant of magnitudes of an aftershock sequence since the mainshock. This comes out to be a remarkable straight line whose slope is characteristic of the fault zone. This will provide an useful tool in understanding the temporal distribution of aftershocks after a specific mainshock.
Design optimization for security-and safety-critical distributed real-time applications
DEFF Research Database (Denmark)
Jiang, Wei; Pop, Paul; Jiang, Ke
2016-01-01
In this paper, we are interested in the design of real-time applications with security, safety, timing, and energy requirements. The applications are scheduled with cyclic scheduling, and are mapped on distributed heterogeneous architectures. Cryptographic services are deployed to satisfy securit...
RTnet: a distributed real-time protocol for broadcast-capable networks
Hanssen, Ferdy; Jansen, Pierre G.; Scholten, Hans; Mullender, Sape
2005-01-01
RTnet is a distributed real-time network protocol, to be used on fully-connected local area networks with a broadcast capability. It supports on-the-fly addition and removal of network nodes, resource-lavish and resourcelean devices, streaming real-time and regular non-realtime traffic. It allows th
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
Age Dating Fluvial Sediment Storage Reservoirs to Construct Sediment Waiting Time Distributions
Skalak, K.; Pizzuto, J. E.; Benthem, A.; Karwan, D. L.; Mahan, S.
2015-12-01
Suspended sediment transport is an important geomorphic process that can often control the transport of nutrients and contaminants. The time a particle spends in storage remains a critical knowledge gap in understanding particle trajectories through landscapes. We dated floodplain deposits in South River, VA, using fallout radionuclides (Pb-210, Cs-137), optically stimulated luminescence (OSL), and radiocarbon dating to determine sediment ages and construct sediment waiting time distributions. We have a total of 14 age dates in two eroding banks. We combine these age dates with a well-constrained history of mercury concentrations on suspended sediment in the river from an industrial release. Ages from fallout radionuclides document sedimentation from the early 1900s to the present, and agree with the history of mercury contamination. OSL dates span approximately 200 to 17,000 years old. We performed a standard Weibull analysis of nonexceedance to construct a waiting time distribution of floodplain sediment for the South River. The mean waiting time for floodplain sediment is 2930 years, while the median is approximately 710 years. When the floodplain waiting time distribution is combined with the waiting time distribution for in-channel sediment storage (available from previous studies), the mean waiting time shifts to approximately 680 years, suggesting that quantifying sediment waiting times for both channel and floodplain storage is critical in advancing knowledge of particle trajectories through watersheds.
Energy-Aware Synthesis of Fault-Tolerant Schedules for Real-Time Distributed Embedded Systems
DEFF Research Database (Denmark)
Poulsen, Kåre Harbo; Pop, Paul; Izosimov, Viacheslav
2007-01-01
This paper presents a design optimisation tool for distributed embedded real-time systems that 1) decides mapping, fault-tolerance policy and generates a fault-tolerant schedule, 2) is targeted for hard real-time, 3) has hard reliability goal, 4) generates static schedule for processes and messages...
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
Directory of Open Access Journals (Sweden)
Bin Wang
2016-01-01
Full Text Available This paper studies the application of frequency distributed model for finite time control of a fractional order nonlinear hydroturbine governing system (HGS. Firstly, the mathematical model of HGS with external random disturbances is introduced. Secondly, a novel terminal sliding surface is proposed and its stability to origin is proved based on the frequency distributed model and Lyapunov stability theory. Furthermore, based on finite time stability and sliding mode control theory, a robust control law to ensure the occurrence of the sliding motion in a finite time is designed for stabilization of the fractional order HGS. Finally, simulation results show the effectiveness and robustness of the proposed scheme.
The current duration design for estimating the time to pregnancy distribution
DEFF Research Database (Denmark)
Gasbarra, Dario; Arjas, Elja; Vehtari, Aki
2015-01-01
This paper was inspired by the studies of Niels Keiding and co-authors on estimating the waiting time-to-pregnancy (TTP) distribution, and in particular on using the current duration design in that context. In this design, a cross-sectional sample of women is collected from those who are currently...... attempting to become pregnant, and then by recording from each the time she has been attempting. Our aim here is to study the identifiability and the estimation of the waiting time distribution on the basis of current duration data. The main difficulty in this stems from the fact that very short waiting...
Real-Time Congestion Management in Distribution Networks by Flexible Demand Swap
DEFF Research Database (Denmark)
Huang, Shaojun; Wu, Qiuwei
2017-01-01
consumption or production. Flexibility service from demand will be a good option to solve the real-time congestions if the cost of activating the flexibility service is fully addressed. This paper proposes a new method, namely “swap”, to employ the flexibility service from electric vehicles (EVs) and heat......In addition to the day-ahead congestion management in distribution networks, the real-time congestion management is very important because many unforeseen events can occur at the real operation time, e.g. loss of generation of distributed energy resources (DERs) or inaccurate forecast of energy...
LHCb : Clock and timing distribution in the LHCb upgraded detector and readout system
Alessio, Federico; Barros Marin, M; Cachemiche, JP; Hachon, F; Jacobsson, Richard; Wyllie, Ken
2014-01-01
The LHCb experiment is upgrading part of its detector and the entire readout system towards a full 40 MHz readout system in order to run between five and ten times its initial design luminosity and increase its trigger efficiency. In this paper, the new timing, trigger and control distribution system for such an upgrade is reviewed with particular attention given to the distribution of the clock and timing information across the entire readout system, up to the FE and the on-detector electronics. Current ideas are here presented in terms of reliability, jitter, complexity and implementation.
SAFCM: A Security-Aware Feedback Control Mechanism for Distributed Real-Time Embedded Systems
DEFF Research Database (Denmark)
Ma, Yue; Jiang, Wei; Sang, Nan
2012-01-01
-time systems, a multi-input multi-output feedback loop is designed and a model predictive controller is deployed based on an equation model that describes the dynamic behavior of the DRE systems. This control loop uses security level scaling to globally control the CPU utilization and security performance......Distributed Real-time Embedded (DRE) systems are facing great challenges in networked, unpredictable and especially unsecured environments. In such systems, there is a strong need to enforce security on distributed computing nodes in order to guard against potential threats, while satisfying...... the real-time requirements. This paper proposes a Security-Aware Feedback Control Mechanism (SAFCM) which has the ability to dynamically change the security level to guarantee soft real-time requirements and make the security protection as strong as possible. In order to widely support distributed real...
DEFF Research Database (Denmark)
Blurton, Steven Paul; Kesselmeier, M.; Gondan, Matthias
2012-01-01
related work on the density of first-passage times [Navarro, D.J., Fuss, I.G. (2009). Fast and accurate calculations for first-passage times in Wiener diffusion models. Journal of Mathematical Psychology, 53, 222-230]. Two representations exist for the distribution, both including infinite series. We......We propose an improved method for calculating the cumulative first-passage time distribution in Wiener diffusion models with two absorbing barriers. This distribution function is frequently used to describe responses and error probabilities in choice reaction time tasks. The present work extends...... derive upper bounds for the approximation error resulting from finite truncation of the series, and we determine the number of iterations required to limit the error below a pre-specified tolerance. For a given set of parameters, the representation can then be chosen which requires the least...
Optimal distribution of integration time for intensity measurements in Stokes polarimetry.
Li, Xiaobo; Liu, Tiegen; Huang, Bingjing; Song, Zhanjie; Hu, Haofeng
2015-10-19
We consider the typical Stokes polarimetry system, which performs four intensity measurements to estimate a Stokes vector. We show that if the total integration time of intensity measurements is fixed, the variance of the Stokes vector estimator depends on the distribution of the integration time at four intensity measurements. Therefore, by optimizing the distribution of integration time, the variance of the Stokes vector estimator can be decreased. In this paper, we obtain the closed-form solution of the optimal distribution of integration time by employing Lagrange multiplier method. According to the theoretical analysis and real-world experiment, it is shown that the total variance of the Stokes vector estimator can be significantly decreased about 40% in the case discussed in this paper. The method proposed in this paper can effectively decrease the measurement variance and thus statistically improves the measurement accuracy of the polarimetric system.
Li, Xiaobo; Hu, Haofeng; Liu, Tiegen; Huang, Bingjing; Song, Zhanjie
2016-04-04
We consider the degree of linear polarization (DOLP) polarimetry system, which performs two intensity measurements at orthogonal polarization states to estimate DOLP. We show that if the total integration time of intensity measurements is fixed, the variance of the DOLP estimator depends on the distribution of integration time for two intensity measurements. Therefore, by optimizing the distribution of integration time, the variance of the DOLP estimator can be decreased. In this paper, we obtain the closed-form solution of the optimal distribution of integration time in an approximate way by employing Delta method and Lagrange multiplier method. According to the theoretical analyses and real-world experiments, it is shown that the variance of the DOLP estimator can be decreased for any value of DOLP. The method proposed in this paper can effectively decrease the measurement variance and thus statistically improve the measurement accuracy of the polarimetry system.
Directory of Open Access Journals (Sweden)
Yoanna Schulz-Zhecheva
2016-07-01
Full Text Available Mean reaction times (RT and the intra-subject variability of RT in simple RT tasks have been shown to predict higher-order cognitive abilities measured with psychometric intelligence tests. To further explore this relationship and to examine its generalizability to a sub-adult-aged sample, we administered different choice RT tasks and Cattell’s Culture Fair Intelligence Test (CFT 20-R to n = 362 participants aged eight to 18 years. The parameters derived from applying Ratcliff’s diffusion model and an ex-Gaussian model to age-residualized RT data were used to predict fluid intelligence using structural equation models. The drift rate parameter of the diffusion model, as well as σ of the ex-Gaussian model, showed substantial predictive validity regarding fluid intelligence. Our findings demonstrate that stability of performance, more than its mere speed, is relevant for fluid intelligence and we challenge the universality of the worst performance rule observed in adult samples.
Segvić Klarić, M; Kosalec, I; Mastelić, J; Piecková, E; Pepeljnak, S
2007-01-01
To characterize antifungal activities of essential oil of thyme (Thymus vulgaris L.) and pure thymol, as comparative substance, on different mould species isolated from damp dwellings. Fifty samples of wall scrapes were collected from damp dwellings in Zagreb, the capital of Croatia. The members of the following mould genera were recovered from the samples: Aspergillus (44%), Penicillium (18%) Alternaria, Ulocladium, Absidia and Mucor (8%) Cladosporium, Trichoderma and Rhizopus (6%), and Chaetomium (2%). Two strains of Stachybotrys chartarum were isolated from damp dwellings in Slovakia. Antifungal activities of the thyme essential oil, which contains p-cymene (36.5%), thymol (33.0%) and 1,8-cineole (11.3%) as main components, and pure thymol were determined by the dilution method and exposure to vaporous phase of the oil. Minimum inhibitory concentrations (MIC) of both thymol and essential oil were bellow 20 microg ml(-1), except for Mucor spp. (50.20 microg ml(-1)). Thymol exhibited approximately three-times stronger inhibition than essential oil of thyme. The vaporous phase of the thyme essential oil (82 microg l(-1)) in glass chambers strongly suppressed the sporulation of moulds during 60 days of exposure. The thyme essential oil possesses a wide range spectrum of fungicidal activity. The vaporous phase of the oil exhibited long-lasting suppressive activity on moulds from damp dwellings. Essential oil of thyme and thymol could be used for disinfection of mouldy walls in the dwellings in low concentration.
Scaling Analysis of Time Distribution between Successive Earthquakes in Aftershock Sequences
Marekova, Elisaveta
2016-08-01
The earthquake inter-event time distribution is studied, using catalogs for different recent aftershock sequences. For aftershock sequences following the Modified Omori's Formula (MOF) it seems clear that the inter-event distribution is a power law. The parameters of this law are defined and they prove to be higher than the calculated value (2-1/ p). Based on the analysis of the catalogs, it is determined that the probability densities of the inter-event time distribution collapse into a single master curve when the data is rescaled with instantaneous intensity, R( t; M th ), defined by MOF. The curve is approximated by a gamma distribution. The collapse of the data provides a clear view of aftershock-occurrence self-similarity.
Sub-nanosecond machine timing and frequency distribution via serial data links
Rohlev, A; Serrano, J; Cattin, M; Settler, M
2008-01-01
FERMI@ELETTRA is a 4th generation light source under construction at Sincrotrone Trieste. It will be operated as a seeded FEL driven by a warm S-band Linac which places very stringent specifications on control of the amplitude and phase of the RF stations. The local clock generation and distribution system at each station will not be based on the phase reference distribution but rather on a separate frequency reference distribution which has significantly less stringent phase stability requirements. This frequency reference will be embedded in the serial data link to each station and has the further advantage of being able to broadcast synchronous machine timing signals with sub-nanosecond temporal accuracy. The phase and amplitude of the phase reference line is measured for each pulse and used to calibrate the other measurements. This paper describes the architecture used to distribute the frequency reference along with the precision machine timing and clocking signals.
Scaling Analysis of Time Distribution between Successive Earthquakes in Aftershock Sequences
Directory of Open Access Journals (Sweden)
Marekova Elisaveta
2016-08-01
Full Text Available The earthquake inter-event time distribution is studied, using catalogs for different recent aftershock sequences. For aftershock sequences following the Modified Omori’s Formula (MOF it seems clear that the inter-event distribution is a power law. The parameters of this law are defined and they prove to be higher than the calculated value (2 – 1/p. Based on the analysis of the catalogs, it is determined that the probability densities of the inter-event time distribution collapse into a single master curve when the data is rescaled with instantaneous intensity, R(t; Mth, defined by MOF. The curve is approximated by a gamma distribution. The collapse of the data provides a clear view of aftershock-occurrence self-similarity.
Product Design Time Forecasting by Kernel-Based Regression with Gaussian Distribution Weights
Directory of Open Access Journals (Sweden)
Zhi-Gen Shang
2016-06-01
Full Text Available There exist problems of small samples and heteroscedastic noise in design time forecasts. To solve them, a kernel-based regression with Gaussian distribution weights (GDW-KR is proposed here. GDW-KR maintains a Gaussian distribution over weight vectors for the regression. It is applied to seek the least informative distribution from those that keep the target value within the confidence interval of the forecast value. GDW-KR inherits the benefits of Gaussian margin machines. By assuming a Gaussian distribution over weight vectors, it could simultaneously offer a point forecast and its confidence interval, thus providing more information about product design time. Our experiments with real examples verify the effectiveness and flexibility of GDW-KR.
Real-Time Analysis and Forecasting of Multisite River Flow Using a Distributed Hydrological Model
Directory of Open Access Journals (Sweden)
Mingdong Sun
2014-01-01
Full Text Available A spatial distributed hydrological forecasting system was developed to promote the analysis of river flow dynamic state in a large basin. The research presented the real-time analysis and forecasting of multisite river flow in the Nakdong River Basin using a distributed hydrological model with radar rainfall forecast data. A real-time calibration algorithm of hydrological distributed model was proposed to investigate the particular relationship between the water storage and basin discharge. Demonstrate the approach of simulating multisite river flow using a distributed hydrological model couple with real-time calibration and forecasting of multisite river flow with radar rainfall forecasts data. The hydrographs and results exhibit that calibrated flow simulations are very approximate to the flow observation at all sites and the accuracy of forecasting flow is gradually decreased with lead times extending from 1 hr to 3 hrs. The flow forecasts are lower than the flow observation which is likely caused by the low estimation of radar rainfall forecasts. The research has well demonstrated that the distributed hydrological model is readily applicable for multisite real-time river flow analysis and forecasting in a large basin.
Transition path time distribution and the transition path free energy barrier.
Pollak, Eli
2016-10-19
The recent experimental measurement of the transition path time distributions of proteins presents several challenges to theory. Firstly, why do the fits of the experimental data to a theoretical expression lead to barrier heights which are much lower than the free energies of activation of the observed transitions? Secondly, there is the theoretical question of determining the transition path time distribution, without invoking the Smoluchowski limit. In this paper, we derive an exact expression for a transition path time distribution which is valid for arbitrary memory friction using the normal mode transformation which underlies Kramers' rate theory. We then recall that for low barriers, there is a noticeable difference between the transition path time distribution obtained with absorbing boundary conditions and free boundary conditions. For the former, the transition times are shorter, since recrossings of the boundaries are disallowed. As a result, if one uses the distribution based on absorbing boundary conditions to fit the experimental data, one will find that the transition path barrier will be larger than the values found based on a theory with free boundary conditions. We then introduce the paradigm of a transition path barrier height, and show that one should always expect it to be much smaller than the activation energy.
Boltzmann-Gibbs Distribution of Fortune and Broken Time-Reversible Symmetry in Econodynamics
Ao, P
2005-01-01
Within the description of stochastic differential equations it is argued that the existence of Boltzmann-Gibbs type distribution in economy is independent of the time reversal symmetry in econodynamics. Both power law and exponential distributions can be accommodated by it. The demonstration is based on a mathematical structure discovered during a study in gene regulatory network dynamics. Further possible analogy between equilibrium economy and thermodynamics is explored.
Lenart, Łukasz
2011-01-01
The aim of this article is to establish asymptotic distributions and consistency of subsampling for spectral density and for magnitude of coherence for non-stationary, almost periodically correlated time series. We show the asymptotic normality of the spectral density estimator and the limiting distribution of a magnitude of coherence statistic for all points from the bifrequency square. The theoretical results hold under $\\alpha$-mixing and moment conditions.
Wang, Xinghu; Hong, Yiguang; Yi, Peng; Ji, Haibo; Kang, Yu
2017-05-24
In this paper, a distributed optimization problem is studied for continuous-time multiagent systems with unknown-frequency disturbances. A distributed gradient-based control is proposed for the agents to achieve the optimal consensus with estimating unknown frequencies and rejecting the bounded disturbance in the semi-global sense. Based on convex optimization analysis and adaptive internal model approach, the exact optimization solution can be obtained for the multiagent system disturbed by exogenous disturbances with uncertain parameters.
Directory of Open Access Journals (Sweden)
Howard A. Gaberson
1995-01-01
Full Text Available This article discusses time frequency analysis of machinery diagnostic vibration signals. The short time Fourier transform, the Wigner, and the Choi–Williams distributions are explained and illustrated with test cases. Examples of Choi—Williams analyses of machinery vibration signals are presented. The analyses detect discontinuities in the signals and their timing, amplitude and frequency modulation, and the presence of different components in a vibration signal.
A hybrid model for improving response time in distributed data mining.
Krishnaswamy, Shonali; Loke, Seng W; Zaslasvky, Arkady
2004-12-01
This paper presents a hybrid distributed data mining (DDM) model for optimization of response time. The model combines a mobile agent approach with client server strategies to reduce the overall response time. The hybrid model proposes and develops accurate a priori estimates of the computation and communication components of response time as the costing strategy to support optimization. Experimental evaluation of the hybrid model is presented.
Modelling water quality in drinking water distribution networks from real-time direction data
Directory of Open Access Journals (Sweden)
S. Nazarovs
2012-03-01
Full Text Available Modelling of contamination spread and location of contamination source in a water distribution network is an important task. The paper considers applicability of real-time flow direction data based model for contaminant transport for a distribution network of a city. Simulations of several contamination scenarios are made to evaluate necessary number of flow direction sensors. It is found that for a model, containing major pipes of Riga distribution system, sensor number decrease from 927 to 207 results in average 20% increase of simulated contaminated length of pipes. Simulation data suggest that optimal number of sensors for Riga model is around 200.
DEFF Research Database (Denmark)
Zhang, Chunyu; Wang, Qi; Wang, Jianhui;
2016-01-01
and inelastic demand components. A one-leader multi-follower bilevel model is proposed to derive the procurement strategies, i.e., the upper-level problem intends to maximize the profit of the proactive distribution company, while the lower-level expresses the profit maximization per rational aggregator......In this paper, we present a real-time trading framework for distribution networks where a rational aggregator is identified as a broker by contracting with individual demands and dealing with the distribution company. Demand response capability is characterized by the coexistence of elastic...
Execution time supports for adaptive scientific algorithms on distributed memory machines
Berryman, Harry; Saltz, Joel; Scroggs, Jeffrey
1990-01-01
Optimizations are considered that are required for efficient execution of code segments that consists of loops over distributed data structures. The PARTI (Parallel Automated Runtime Toolkit at ICASE) execution time primitives are designed to carry out these optimizations and can be used to implement a wide range of scientific algorithms on distributed memory machines. These primitives allow the user to control array mappings in a way that gives an appearance of shared memory. Computations can be based on a global index set. Primitives are used to carry out gather and scatter operations on distributed arrays. Communications patterns are derived at runtime, and the appropriate send and receive messages are automatically generated.
New models and distributions of the electrical breakdown time delay in neon
Energy Technology Data Exchange (ETDEWEB)
Stamenkovic, S N, E-mail: ssuzana@pmf.ni.ac.rs [Department of Physics, University of Nis, P.O. BOX 224, 18001 Nis (Serbia)
2010-11-01
The measurements of the electrical breakdown time delay t{sub d} for a wide range of working voltages and at different preionization levels are presented. The statistical breakdown time delay t{sub s} and the discharge formative time t{sub f} are experimentally separated and theoretical models of their dependencies on the overvoltage and number densities of residual charges during relaxation are suggested. Several empirical and semiempirical models are used to describe the formative time delay dependence on working voltages t{sub f} (U). The empirical and theoretical models from the literature are also applied to the experimental data, without and with empirical corrections. Moreover, several new distributions are experimentally obtained: Gauss-exponential, Gaussian and double Gaussian ones for the statistical time delay, as well as Gaussian and double Gaussian distributions for the formative time. The measurements of the breakdown time delay at different preionization levels (afterglow periods) t{sub d} ({tau}) obtained with a galvanic layer of gold and a sub-layer of nickel on the copper cathode are compared to the measurements with a vacuum deposited gold layer on the cathode surface. It was found that the surface charges retaining on a galvanic layer of gold influence the breakdown time delay which leads to double Gaussian distributions of the formative and statistical time delay.
Active and passive cooling methods for dwellings
DEFF Research Database (Denmark)
Oropeza-Perez, Ivan; Østergaard, Poul Alberg
2018-01-01
they might be applied, and what their energy needs are. Secondly, what scientific analysis has been carried out and what the major findings are. Thirdly, what their economic and technical feasibility of use at the stage of implementation and operation within a dwelling are. Then, either with the reviewed......In this document a review of three active as well as ten passive cooling methods suitable for residential buildings is carried out. The review firstly addresses how the various technologies cool the space according to the terms of the building heat balance, under what technical conditions...... studies or with a simulation modelling, an assessment of temperature drop of each cooling method within a standard-size dwelling is carried out. Also, a comparison of initial investment, energy consumption, maintenance, retrofitting and required space is done. Thereafter, with this information, a decision...
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.
Time-headway distribution for periodic totally asymmetric exclusion process with various updates
Hrabák, P.; Krbálek, M.
2016-03-01
The totally asymmetric exclusion process (TASEP) with periodic boundaries is considered as traffic flow model. The large-L approximation of the stationary state is used for the derivation of the time-headway distribution (an important microscopic characteristic of traffic flow) for the model with generalized update (genTASEP) in both, forward- and backward-sequential representations. The usually used updates, fully-parallel and regular forward- and backward-sequential, are analyzed as special cases of the genTASEP. It is shown that only for those cases, the time-headway distribution is determined by the flow regardless to the density. The qualitative comparison of the results with traffic data demonstrates that the genTASEP with backward order and attractive interaction evinces similar properties of time-headway distribution as the real traffic sample.
Dynamic management of transactions in distributed real-time processing system
Singh, Y Jayanta; Gaikwad, Ashok; Mehrotra, S C; 10.5121/ijdms.2010.2210
2010-01-01
Managing the transactions in real time distributed computing system is not easy, as it has heterogeneously networked computers to solve a single problem. If a transaction runs across some different sites, it may commit at some sites and may failure at another site, leading to an inconsistent transaction. The complexity is increase in real time applications by placing deadlines on the response time of the database system and transactions processing. Such a system needs to process Transactions before these deadlines expired. A series of simulation study have been performed to analyze the performance under different transaction management under conditions such as different workloads, distribution methods, execution mode-distribution and parallel etc. The scheduling of data accesses are done in order to meet their deadlines and to minimize the number of transactions that missed deadlines. A new concept is introduced to manage the transactions in dynamic ways rather than setting computing parameters in static ways...
Directory of Open Access Journals (Sweden)
Hao Lei
2015-12-01
Full Text Available Trip travel time reliability is an important measure of transportation system performance and a key factor affecting travelers’ choices. This paper explores a method for estimating travel time distributions for corridors that contain multiple bottlenecks. A set of analytical equations are used to calculate the number of queued vehicles ahead of a probe vehicle and further capture many important factors affecting travel times: the prevailing congestion level, queue discharge rates at the bottlenecks, and flow rates associated with merges and diverges. Based on multiple random scenarios and a vector of arrival times, the lane-by-lane delay at each bottleneck along the corridor is recursively estimated to produce a route-level travel time distribution. The model incorporates stochastic variations of bottleneck capacity and demand and explains the travel time correlations between sequential links. Its data needs are the entering and exiting flow rates and a sense of the lane-by-lane distribution of traffic at each bottleneck. A detailed vehicle trajectory data-set from the Next Generation SIMulation (NGSIM project has been used to verify that the estimated distributions are valid, and the sources of estimation error are examined.
Effect of music on pain for home-dwelling persons with dementia.
Park, Heeok
2010-09-01
The purpose of this study was to investigate the effect of music on pain for home-dwelling persons with dementia. A quasiexperimental design was used. Fifteen subjects listened to their preferred music for 30 minutes before peak agitation time, for 2 days per week, followed by no music for 2 weeks. The process was repeated once. The finding of this study showed that mean pain levels after listening to music were significantly lower than before listening to the music (t=2.21, df=28; p music intervention to control pain for home-dwelling persons with dementia.
Impact of UK Building Regulations on design and thermal performance of dwellings
Institute of Scientific and Technical Information of China (English)
LIM; D; 姚润明
2009-01-01
This paper looks at the progressive impact of UK Building Regulations (Part L) on the energy consumption of dwellings with respect to thermal performance of the building envelope. It provides an overview of building legislation,highlighting progressive improvement in building elemental U-values and compliance methods. The focus centres on Building Regulations from 1965 to 2006,at a time when energy conservation has become an integral component of building control due to environmental concerns. Simulation software is used to compare energy consumption for 5 typical UK dwelling types through a series of case studies which illustrate the rate of impact over recent years.
A stochastic model of radiation carcinogenesis: Latent time distributions and their properties
Energy Technology Data Exchange (ETDEWEB)
Klebanov, L.V.; Yakovlev, A.Yu. (St. Petersburg Technical Univ. (Russian Federation)); Rachev, S.T. (Univ. of California, Santa Barbara (United States))
1993-01-01
A stochastic model of radiation carcinogenesis is proposed that has much in common with the ideas suggested by M. Pike as early as 1966. The model allows one to obtain a parametric family of substochastic-type distributions for the time of tumor latency that provides a description of the rate of tumor development and the number of affected individuals. With this model it is possible to interpret data on tumor incidence in terms of promotion and progression processes. The basic model is developed for a prolonged irradiation at a constant dose rate and includes short-term irradiation as a special case. A limiting form of the latent time distribution for short-term irradiation at high doses is obtained. This distribution arises in the extreme value theory within the random minima framework. An estimate for the rate of convergence to a limiting distributions is given. Based on the proposed latent time distributions, long-term predictions of carcinogenic risk do not call for information about irradiation dose. As shown by computer simulation studies and real data analysis, the parametric estimation of carcinogenic risk appears to be robust to the loss of statistical information caused by the right-hand censoring of time-to-tumor observations. It seems likely that this property, although revealed by means of a purely empirical procedure, may be useful in selecting a model for the practical purpose of risk prediction. 44 refs., 3 figs., 1 tab.
Uncertainty analysis of energy consumption in dwellings
Energy Technology Data Exchange (ETDEWEB)
Pettersen, Trine Dyrstad
1997-12-31
This thesis presents a comprehensive study of an energy estimation model that can be used to examine the uncertainty of predicted energy consumption in a dwelling. The variation and uncertainty of input parameters due to the outdoor climate, the building construction and the inhabitants are studied as a basis for further energy evaluations. The occurring variations of energy consumption in nominal similar dwellings are also investigated due to verification of the simulated energy consumption. The main topics are (1) a study of expected variations and uncertainties in both input parameters used in energy consumption calculations and the energy consumption in the dwelling, (2) the development and evaluation of a simplified energy calculation model that considers uncertainties due to the input parameters, (3) an evaluation of the influence of the uncertain parameters on the total variation so that the most important parameters can be identified, and (4) the recommendation of a simplified procedure for treating uncertainties or possible deviations from average conditions. 90 refs., 182 figs., 73 tabs.
Building XenoBuntu Linux Distribution for Teaching and Prototyping Real-Time Operating Systems
Litayem, Nabil; Saoud, Slim Ben
2011-01-01
This paper describes the realization of a new Linux distribution based on Ubuntu Linux and Xenomai Real-Time framework. This realization is motivated by the eminent need of real-time systems in modern computer science courses. The majority of the technical choices are made after qualitative comparison. The main goal of this distribution is to offer standard Operating Systems (OS) that include Xenomai infrastructure and the essential tools to begin hard real-time application development inside a convivial desktop environment. The released live/installable DVD can be adopted to emulate several classic RTOS Application Program Interfaces (APIs), directly use and understand real-time Linux in convivial desktop environment and prototyping real-time embedded applications.
Tomadakis, Manolis M.; Robertson, Teri J.
2003-07-01
We present a random walk based investigation of the pore size probability distribution and its moments, the survival probability and mean survival time, and the principal relaxation time, for random and ordered arrays of cylindrical fibers of various orientation distributions. The dimensionless mean survival time, principal relaxation time, mean pore size, and mean square pore size are found to increase with porosity, remain practically independent of the directionality of random fiber beds, and attain lower values for ordered arrays. Wide pore size distributions are obtained for random fiber structures and relatively narrow for ordered square arrays, all in very good agreement with theoretically predicted limiting values. Analytical results derived for the pore size probability and its lower moments for square arrays of fibers practically coincide with the corresponding simulation results. Earlier variational bounds on the mean survival time and principal relaxation time are obeyed by our numerical results in all cases, and are found to be quite sharp up to very high porosities. Dimensionless groups representing the deviation of such bounds from our simulation results vary in practically the same range as the corresponding values reported earlier for beds of spherical particles. A universal scaling expression of the literature relating the mean survival time to the mean pore size [S. Torquato and C. L. Y. Yeong, J. Chem. Phys. 106, 8814 (1997)] agrees very well with our results for all types of fiber structures, thus validated for the first time for anisotropic porous media.
DEFF Research Database (Denmark)
Kumar, Ashish; Vercruysse, Jurgen; Vanhoorne, Valerie
2015-01-01
within each module where different granulation rate processes dominate over others. Currently, experimental data is used to determine the residence time distributions. In this study, a conceptual model based on classical chemical engineering methods is proposed to better understand and simulate...... the residence time distribution in a TSG. The experimental data were compared with the proposed most suitable conceptual model to estimate the parameters of the model and to analyse and predict the effects of changes in number of kneading discs and their stagger angle, screw speed and powder feed rate...
Directory of Open Access Journals (Sweden)
Yan Che
2012-01-01
Full Text Available The estimation problem is investigated for a class of stochastic nonlinear systems with distributed time-varying delays and missing measurements. The considered distributed time-varying delays, stochastic nonlinearities, and missing measurements are modeled in random ways governed by Bernoulli stochastic variables. The discussed nonlinearities are expressed by the statistical means. By using the linear matrix inequality method, a sufficient condition is established to guarantee the mean-square stability of the estimation error, and then the estimator parameters are characterized by the solution to a set of LMIs. Finally, a simulation example is exploited to show the effectiveness of the proposed design procedures.
Approximating response time distributions in closed queueing network models of computer performance
Energy Technology Data Exchange (ETDEWEB)
Salza, S.; Lavenberg, S.S.
1981-01-01
Hierarchical decomposition methods for approximating response time distributions in certain closed queueing network models of computer performance are investigated. The methods investigated apply whenever part of a customer's response time consists of a geometrically distributed number of successive cycles within a subnetwork. The key step involves replacing the subnetwork with parallel exponential servers having queue-size dependent service rates. Results on thinning stochastic point processes are used to justify this replacement when the mean number of cycles is large. Preliminary numerical comparisons of the approximations with simulation results indicate that the approximations are quite accurate even when the mean number of cycles is small. 17 references.
Interference structure of shallow water reverberation in time-frequency distribution
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
The striations of the reverberation spectrum in the time-frequency distribution were observed in a shallow water acoustic experiment in 2002. A model following the coherent reverberation model developed in 2002 is presented to explain the observed striations. To examine the consistency between the measured data and numerical predictions, we have used a method based on Radon transform for determining the slope of the striations to the measured reverberation data and numerical predictions. The results indicate that the previously developed coherent reverberation model can predict the interference structure of the reverberation intensity in the time-frequency distribution.
Estimating the distribution of rest-frame time-scales for blazar jets: a statistical approach
Liodakis, I.; Blinov, D.; Papadakis, I.; Pavlidou, V.
2017-03-01
In any flux-density limited sample of blazars, the distribution of the time-scale modulation factor Δt΄/Δt, which quantifies the change in observed time-scales compared to the rest-frame ones due to redshift and relativistic compression follows an exponential distribution with a mean depending on the flux limit of the sample. In this work, we produce the mathematical formalism that allows us to use this information in order to uncover the underlining rest-frame probability density function of measurable time-scales of blazar jets. We extensively test our proposed methodology using a simulated Flat Spectrum Radio Quasar population with a 1.5 Jy flux-density limit in the simple case (where all blazars share the same intrinsic time-scale), in order to identify limits of applicability and potential biases due to observational systematics and sample selection. We find that for monitoring with time intervals between observations longer than ∼30 per cent of the intrinsic time-scale under investigation the method loses its ability to produce robust results. For time intervals of ∼3 per cent of the intrinsic time-scale, the error of the method is as low as 1 per cent in recovering the intrinsic rest-frame time-scale. We applied our method to rotations of the optical polarization angle of blazars observed by RoboPol. We found that the intrinsic time-scales of the longest duration rotation event in each blazar follows a narrow distribution, well described by a normal distribution with mean 87 d and standard deviation 5 d. We discuss possible interpretations of this result.
Directory of Open Access Journals (Sweden)
Yi Zhao
2015-01-01
Full Text Available This study aimed to calibrate saturation flow rate (SFR and start-up lost time (SLT when developing signal timing. In current commonly used methods, SFR for one given lane is usually calibrated from many subjective adjustment factors and a fixed result. SLT is calculated based on the fixed SFR, which prevents local applications in China. Considering the importance of traffic behavior (headway in determining SFR and SLT, this study started from headway distribution and attempted to specify the relationships between headway and vehicle position directly. A common intersection in Nanjing, China, was selected to implement field study and data from 920 queues was collected. Headway distribution was explored and the 78th percentile of headway at each position was selected to build model. Based on the developed relationships, SFR and SLT were calibrated. The results showed that SFR and SLT were correlated with queue length. Moreover, the results showed that it was difficult to reach saturated state even with a long queue length. This paper provides a new perspective on calibrating important parameters in signal timing, which will be useful for traffic agencies to complete signal timing by making the process simpler.
Lee, S. Daniel
1990-01-01
We propose a distributed agent architecture (DAA) that can support a variety of paradigms based on both traditional real-time computing and artificial intelligence. DAA consists of distributed agents that are classified into two categories: reactive and cognitive. Reactive agents can be implemented directly in Ada to meet hard real-time requirements and be deployed on on-board embedded processors. A traditional real-time computing methodology under consideration is the rate monotonic theory that can guarantee schedulability based on analytical methods. AI techniques under consideration for reactive agents are approximate or anytime reasoning that can be implemented using Bayesian belief networks as in Guardian. Cognitive agents are traditional expert systems that can be implemented in ART-Ada to meet soft real-time requirements. During the initial design of cognitive agents, it is critical to consider the migration path that would allow initial deployment on ground-based workstations with eventual deployment on on-board processors. ART-Ada technology enables this migration while Lisp-based technologies make it difficult if not impossible. In addition to reactive and cognitive agents, a meta-level agent would be needed to coordinate multiple agents and to provide meta-level control.
Indoor radon survey in dwellings of some regions in Yemen
Energy Technology Data Exchange (ETDEWEB)
Khayrat, A.H. E-mail: akhayrat@yahoo.com; Al-Jarallah, M.I.; Fazal-ur-Rehman, X.; Abu-Jarad, F
2003-06-01
Indoor radon survey in a total of 241 dwellings, distributed in some regions of Yemen was performed, using CR-39 based radon monitors. The objective of this radon survey is to get representative indoor radon data of three regions, namely Dhamar, Taiz and Hodeidah, situated at different altitudes above sea level. The radon concentrations varied from 3 to 270 Bq m{sup -3} with an average of 42 Bq m{sup -3}. It was found that the average radon concentration in the surveyed areas increases with altitudes. The highest average radon concentration of 59 Bq m{sup -3} was found in Dhamar city while the lowest average concentration of 8 Bq m{sup -3} was found in Hodeidah city.
Photoelectron track length distributions measured in a negative ion time projection chamber
Prieskorn, Z R; Kaaret, P E; Black, J K
2014-01-01
We report photoelectron track length distributions between 3 and 8 keV in gas mixtures of Ne+CO2+CH3NO2 (260:80:10 Torr) and CO2+CH3NO2 (197.5: 15 Torr). The measurements were made using a negative ion time projection chamber (NITPC) at the National Synchrotron Light Source (NSLS) at the Brookhaven National Laboratory (BNL). We report the first quantitative analysis of photoelectron track length distributions in a gas. The distribution of track lengths at a given energy is best fit by a lognormal distribution. A powerlaw distribution of the form, f(E)=a(E/Eo)n, is found to fit the relationship between mean track length and energy. We find n=1.29 +/- 0.07 for Ne+CO2+CH3NO2 and n=1.20 +/- 0.09 for CO2+CH3NO2. Understanding the distribution of photoelectron track lengths in proportional counter gases is important for optimizing the pixel size and the dimensions of the active region in electron-drift time projection chambers (TPCs) and NITPC X-ray polarimeters.
Weak Serializable Concurrency Control in Distributed Real-Time Database Systems
Institute of Scientific and Technical Information of China (English)
党德鹏; 刘云生; 等
2002-01-01
Most of the proposed concurrency control protocols for real-time database systems are based on serializability theorem.Owing to the unique characteristics of real-time database applications and the importance of satisfying the timing constraints of transactions,serializability is too strong as a correctness criterion and not suitable for real-time databases in most cases.On the other hand,relaxed serializability including epsilon-serializability and similarity-serializability can allow more real-time transactions to satisfy their timing constraints,but database consistency may be sacrificed to some extent.We thus propose the use of weak serializability(WSR)that is more relaxed than conflicting serializability while database consistency is maintained.In this paper,we first formally define the new notion of correctness called weak serializability.After the necessary and sufficient conditions for weak serializability are shown,corresponding concurrency control protocol WDHP(weak serializable distributed high prority protocol)is outlined for distributed real time databases,where a new lock mode called mask lock mode is proposed for simplifying the condition of global consistency.Finally,through a series of simulation studies,it is shown that using the new concurrency control protocol the performance of distributed realtime databases can be greatly improved.
A distributed multiprocessor system designed for real-time image processing
Yin, Zhiyi; Heng, Wei
2008-11-01
In real-time image processing, a large amount of data is needed to be processed at a very high speed. Considering the problems faced in real-time image processing, a distributed multiprocessor system is proposed in this paper. In the design of the distributed multiprocessor system, processing tasks are allocated to various processes, which are bound to different CPUs. Several designs are discussed, and making full use of every process is very important to system's excellent performance. Furthermore, the problems of realization fasten on the inter-process communication, the synchronization, and the stability. System analysis and performance tests both show that the distributed multiprocessor system is able to improve system's performance variously, including the delay, the throughput rate, the stability, the scalability. And the system can be expanded easy at aspects of software and hardware. In a word, the distributed multiprocessor system designed for real-time image processing, based on distributed algorithms, not only improves system's performance variously, but also costs low and expands easy.
Recoil-deposited Po-210 in radon dwellings
Energy Technology Data Exchange (ETDEWEB)
Samuelsson, C.
1990-12-31
Short-lived decay products of Rn-222 plate out on all surfaces in a house containing radon gas. Following the subsequent alpha decays of the mother nuclei, the daughter products Pb-214 and Pb-210 are superficially and permanently absorbed. Due to its long half-life (22 y) the activity of absorbed Pb-210 accumulates in the surface. The activity of Pb-210, or its decay products, can thus reflect the past randon daughter and plate-out history of a house over several decades. Our results and experience from measurements of Po-210 and Rn-222 in 22 dwellings will be presented. In these studies the Po-210 surface activity of one plane glass sheet per dwelling (window panes were not used) has been determined and compared with the period of exposure times the mean radon concentration measured over a two-month period. Considering the large uncertainty in the integrated radon exposure estimate the surface {sup 210}Po correlates well (r=0.73) with the accumulated radon exposure. The {sup 210}Po activity of the glass samples has been measured non-destructively using an open-flow pulse ionization chamber and this detector has also been successfully applied in field exercises.
Recoil-deposited Po-210 in radon dwellings
Energy Technology Data Exchange (ETDEWEB)
Samuelsson, C.
1990-01-01
Short-lived decay products of Rn-222 plate out on all surfaces in a house containing radon gas. Following the subsequent alpha decays of the mother nuclei, the daughter products Pb-214 and Pb-210 are superficially and permanently absorbed. Due to its long half-life (22 y) the activity of absorbed Pb-210 accumulates in the surface. The activity of Pb-210, or its decay products, can thus reflect the past randon daughter and plate-out history of a house over several decades. Our results and experience from measurements of Po-210 and Rn-222 in 22 dwellings will be presented. In these studies the Po-210 surface activity of one plane glass sheet per dwelling (window panes were not used) has been determined and compared with the period of exposure times the mean radon concentration measured over a two-month period. Considering the large uncertainty in the integrated radon exposure estimate the surface {sup 210}Po correlates well (r=0.73) with the accumulated radon exposure. The {sup 210}Po activity of the glass samples has been measured non-destructively using an open-flow pulse ionization chamber and this detector has also been successfully applied in field exercises.
{sup 220}Rn and its progeny in dwellings of Korea
Energy Technology Data Exchange (ETDEWEB)
Kim, Chang-Kyu [International Atomic Energy Agency, Agency' s Laboratories, A-1400, Vienna (Austria)], E-mail: chang.kyu.kim@iaea.org; Kim, Young-Jae; Lee, Hwa-Yong; Chang, Byung-Uck [Korea Institute of Nuclear Safety, P.O. Box 114, Yusong, Daejeon 305-338 (Korea, Republic of); Tokonami, Shinji [Radon Research Group, National Institute of Radiological Sciences (Japan)
2007-09-15
Concentrations of {sup 220}Rn and its progeny were measured in 450 dwellings from 2002 to 2004 using two kinds of simple passive {sup 222}Rn and {sup 220}Rn monitors, Radopot{sup TM} and {sup 220}Rn progeny monitor. The annual arithmetic mean (AM) and geometric mean (GM) of {sup 220}Rn concentrations were 40.4 and 10.7Bqm{sup -3}, respectively. The annual arithmetic mean (AM) of EEC{sub Tn} concentration was 0.89{+-}0.70Bqm{sup -3}, and the annual geometric mean (GM) was 0.60Bqm{sup -3} (95% confidence interval: 0.43-0.78Bqm{sup -3}). The concentrations of {sup 220}Rn in Korean-style houses built with mud block were about two times higher than those in apartments. The average annual effective dose due to inhalation exposure to {sup 220}Rn and its progeny in dwellings was 0.25mSvy{sup -1}.
Bayesian inference for multivariate point processes observed at sparsely distributed times
DEFF Research Database (Denmark)
Rasmussen, Jakob Gulddahl; Møller, Jesper; Aukema, B.H.;
normalizing constants. We discuss the advantages and disadvantages of using continuous time processes compared to discrete time processes in the setting of the present paper as well as other spatial-temporal situations. Keywords: Bark beetle, conditional intensity, forest entomology, Markov chain Monte Carlo......We consider statistical and computational aspects of simulation-based Bayesian inference for a multivariate point process which is only observed at sparsely distributed times. For specicity we consider a particular data set which has earlier been analyzed by a discrete time model involving unknown...
Methods of Run-Time Error Detection in Distributed Process Control Software
DEFF Research Database (Denmark)
Drejer, N.
of generic run-time error types, design of methods of observing application software behaviorduring execution and design of methods of evaluating run time constraints. In the definition of error types it is attempted to cover all relevant aspects of the application softwaree behavior. Methods of observation...... and constraint evaluation is designed for the modt interesting error types. These include: a) semantical errors in data communicated between application tasks; b) errors in the execution of application tasks; and c) errors in the timing of distributed events emitted by the application software. The design......In this thesis, methods of run-time error detection in application software for distributed process control is designed. The error detection is based upon a monitoring approach in which application software is monitored by system software during the entire execution. The thesis includes definition...
Continuous-Time Discrete-Distribution Theory for Activity-Driven Networks
Zino, Lorenzo; Rizzo, Alessandro; Porfiri, Maurizio
2016-11-01
Activity-driven networks are a powerful paradigm to study epidemic spreading over time-varying networks. Despite significant advances, most of the current understanding relies on discrete-time computer simulations, in which each node is assigned an activity potential from a continuous distribution. Here, we establish a continuous-time discrete-distribution framework toward an analytical treatment of the epidemic spreading, from its onset to the endemic equilibrium. In the thermodynamic limit, we derive a nonlinear dynamical system to accurately model the epidemic spreading and leverage techniques from the fields of differential inclusions and adaptive estimation to inform short- and long-term predictions. We demonstrate our framework through the analysis of two real-world case studies, exemplifying different physical phenomena and time scales.
Techniques to Obtain Good Resolution and Concentrated Time-Frequency Distributions: A Review
Directory of Open Access Journals (Sweden)
Imran Shafi
2009-01-01
Full Text Available We present a review of the diversity of concepts and motivations for improving the concentration and resolution of time-frequency distributions (TFDs along the individual components of the multi-component signals. The central idea has been to obtain a distribution that represents the signal's energy concentration simultaneously in time and frequency without blur and crosscomponents so that closely spaced components can be easily distinguished. The objective is the precise description of spectral content of a signal with respect to time, so that first, necessary mathematical and physical principles may be developed, and second, accurate understanding of a time-varying spectrum may become possible. The fundamentals in this area of research have been found developing steadily, with significant advances in the recent past.
Validation Support for Distributed Real-Time Embedded Systems in VDM++
DEFF Research Database (Denmark)
S. Fitzgerald, John; Gorm Larsen, Peter; Tjell, Simon
2007-01-01
We present a tool-supported approach to the validation of system-level timing properties in formal models of distributed real-time embedded systems. Our aim is to provide system architects with rapid feedback on the timing characteristics of alternative designs in the often volatile early stages...... of the development cycle. The approach extends the Vienna Development Method (VDM++), a formal objectoriented modeling language with facilities for describing real-time applications deployed over a distributed infrastructure. A new facility is proposed for stating and checking validation conjectures (assertions...... to visualise traces and validation conjecture violations. The approach and tool support are illustrated with a case study based on an in-car radio navigation system....
An Algorithm for Optimized Time, Cost, and Reliability in a Distributed Computing System
Directory of Open Access Journals (Sweden)
Pankaj Saxena
2013-03-01
Full Text Available Distributed Computing System (DCS refers to multiple computer systems working on a single problem. A distributed system consists of a collection of autonomous computers, connected through a network which enables computers to coordinate their activities and to share the resources of the system. In distributed computing, a single problem is divided into many parts, and each part is solved by different computers. As long as the computers are networked, they can communicate with each other to solve the problem. DCS consists of multiple software components that are on multiple computers, but run as a single system. The computers that are in a distributed system can be physically close together and connected by a local network, or they can be geographically distant and connected by a wide area network. The ultimate goal of distributed computing is to maximize performance in a time effective, cost-effective, and reliability effective manner. In DCS the whole workload is divided into small and independent units, called tasks and it allocates onto the available processors. It also ensures fault tolerance and enables resource accessibility in the event that one of the components fails. The problem is addressed of assigning a task to a distributed computing system. The assignment of the modules of tasks is done statically. We have to give an algorithm to solve the problem of static task assignment in DCS, i.e. given a set of communicating tasks to be executed on a distributed system on a set of processors, to which processor should each task be assigned to get the more reliable results in lesser time and cost. In this paper an efficient algorithm for task allocation in terms of optimum time or optimum cost or optimum reliability is presented where numbers of tasks are more then the number of processors.
Schmiedek, Florian; Oberauer, Klaus; Wilhelm, Oliver; Süss, Heinz-Martin; Wittmann, Werner W
2007-08-01
The authors bring together approaches from cognitive and individual differences psychology to model characteristics of reaction time distributions beyond measures of central tendency. Ex-Gaussian distributions and a diffusion model approach are used to describe individuals' reaction time data. The authors identified common latent factors for each of the 3 ex-Gaussian parameters and for 3 parameters central to the diffusion model using structural equation modeling for a battery of choice reaction tasks. These factors had differential relations to criterion constructs. Parameters reflecting the tail of the distribution (i.e., tau in the ex-Gaussian and drift rate in the diffusion model) were the strongest unique predictors of working memory, reasoning, and psychometric speed. Theories of controlled attention and binding are discussed as potential theoretical explanations.
Catching the tail: Empirical identification of the distribution of the value of travel time
DEFF Research Database (Denmark)
Börjesson, Maria; Fosgerau, Mogens; Algers, Staffan
2012-01-01
Recent methodological advances in discrete choice analysis in combination with certain stated choice experiments have allowed researchers to check empirically the identification of the distribution of latent variables such as the value of travel time (VTT). Lack of identification is likely...... to be common and the consequences are severe. E.g., the Danish value of time study found the 15% right tail of the VTT distribution to be unidentified, making it impossible to estimate the mean VTT without resorting to strong assumptions with equally strong impact on the resulting estimate. This paper analyses...... VTT distribution. In addition to informing the design of future choice experiments, the results are also of interest as a validity test of the stated choice methodology. Failure in identifying the right tail of the VTT would have made it difficult to maintain that respondents’ behaviour is consistent...
RIoTBench: A Real-time IoT Benchmark for Distributed Stream Processing Platforms
Shukla, Anshu; Chaturvedi, Shilpa; Simmhan, Yogesh
2017-01-01
The Internet of Things (IoT) is an emerging technology paradigm where millions of sensors and actuators help monitor and manage, physical, environmental and human systems in real-time. The inherent closedloop responsiveness and decision making of IoT applications make them ideal candidates for using low latency and scalable stream processing platforms. Distributed Stream Processing Systems (DSPS) hosted on Cloud data-centers are becoming the vital engine for real-time data processing and anal...
Banishev, Alexandr; Christensen, James M.; Dlott, Dana D.
2017-01-01
We have used fluorescent probes for time-resolved microscopy of shocked particulate media. By embedding rhodamine 6G (R6G) dye in silica nano- and micro-particles, we have created superemissive ultrafast pressure probes. We used silica-embedded dye particles to obtain stroboscopic fluorescence images of shocked sand-like media. Shock effects on microstructured media and micropressure distributions can be determined from shock-induced emission intensity loss, with high time and space resolution.
Meeting the Challenge of Distributed Real-Time & Embedded (DRE) Systems
2012-05-10
Hook for the underlying transport strategy Hook for the event demuxing strategy Consolidating Strategies with Abstract Factory Context Problem...MRI, CT, CR, Ultrasound, etc. Siemens MED Syngo • Common software platform for distributed electronic medical systems • Used by all Siemens MED...mapped to execution platforms UML/Rose ESML/GME PICML/GME ARIES TimeWeaver TimeWiz Cadena PowerPC ACE+TAO Bold Stroke www.rl.af.mil/tech/ programs
Detector dead-time effects and paralyzability in high-speed quantum key distribution
Rogers, Daniel J.; Bienfang, Joshua C.; Nakassis, Anastase; Xu,Hai; Clark, Charles W.
2007-01-01
Recent advances in quantum key distribution (QKD) have given rise to systems that operate at transmission periods significantly shorter than the dead times of their component single-photon detectors. As systems continue to increase in transmission rate, security concerns associated with detector dead times can limit the production rate of sifted bits. We present a model of high-speed QKD in this limit that identifies an optimum transmission rate for a system with given link loss and detector ...
Institute of Scientific and Technical Information of China (English)
Su Weiwei; Chen Yiming
2008-01-01
Delay-dependent robust stability of cellular neural networks with time-varying discrete and distributed time-varying delays is considered. Based on Lyapunov stability theory and the linear matrix inequality (LMIs) technique, delay-dependent stability criteria are derived in terms of LMIs avoiding bounding certain cross terms, which often leads to conservatism. The effectiveness of the proposed stability criteria and the improvement over the existing results are illustrated in the numerical examples.
The last picture show? Timing and order of movie distribution channels
Hennig-Thurau, Thorsten; Henning, Victor; Sattler, Henrik; Eggers, Felix; Houston, Mark B.
2007-01-01
Movies and other media goods are traditionally distributed across distinct sequential channels (e.g., theaters, home video, video on demand). The optimality of the currently employed timing and order of channel openings has become a matter of contentious debate among both industry experts and market
The last picture show? Timing and order of movie distribution channels
Hennig-Thurau, Thorsten; Henning, Victor; Sattler, Henrik; Eggers, Felix; Houston, Mark B.
2007-01-01
Movies and other media goods are traditionally distributed across distinct sequential channels (e.g., theaters, home video, video on demand). The optimality of the currently employed timing and order of channel openings has become a matter of contentious debate among both industry experts and market
DEFF Research Database (Denmark)
Pop, Paul; Eles, Petru; Peng, Zebo;
2004-01-01
In this paper we present an approach to mapping and scheduling of distributed embedded systems for hard real-time applications, aiming at a minimization of the system modification cost. We consider an incremental design process that starts from an already existing system running a set of applicat...
DEFF Research Database (Denmark)
Dou, Chun-Xia; Yue, Dong; Guerrero, Josep M.
2017-01-01
This paper focuses on a multi-agent based distributed coordinated control for radial DC microgrid considering trans-mission time delays. Firstly, a two-level multi-agent system is constructed, where local control is formulated based on local states and executed by means of the first-level agent...
Oudshoorn, F.W.; Kristensen, T.; Sharak Nadimi, I.
2008-01-01
The objective of this paper was to investigate the effect of limited grazing time on urination and defecation frequency, spatial distribution of excrement in the paddock, and the resulting nitrogen balance at animal and field level. During a 6-week period in early summer, 60 Holstein Frisian dairy c
The last picture show? Timing and order of movie distribution channels
Hennig-Thurau, Thorsten; Henning, Victor; Sattler, Henrik; Eggers, Felix; Houston, Mark B.
2007-01-01
Movies and other media goods are traditionally distributed across distinct sequential channels (e.g., theaters, home video, video on demand). The optimality of the currently employed timing and order of channel openings has become a matter of contentious debate among both industry experts and
DEFF Research Database (Denmark)
Andersen, Torben G.; Bollerslev, Tim; Frederiksen, Per Houmann
We provide an empirical framework for assessing the distributional properties of daily specu- lative returns within the context of the continuous-time modeling paradigm traditionally used in asset pricing finance. Our approach builds directly on recently developed realized variation measures and ...
Adaptive synchronization of neural networks with time-varying delay and distributed delay
Wang, Kai; Teng, Zhidong; Jiang, Haijun
2008-01-01
In this paper, the adaptive synchronization of neural networks with time-varying delay and distributed delay is discussed. Based on the LaSalle invariant principle of functional differential equations and the adaptive feedback control technique, some sufficient conditions for adaptive synchronization of such a system are obtained. Finally, a numerical example is given to show the effectiveness of the proposed synchronization method.
Exit times for a class of random walks: exact distribution results
DEFF Research Database (Denmark)
Jacobsen, Martin
2011-01-01
the exit possible has a Laplace transform which is a rational function. The expected exit time is also determined and the paper concludes with exact distribution results concerning exits from bounded intervals. The proofs use simple martingale techniques together with some classical expansions...
Permanence of a Single Species System with Distributed Time Delay and Feedback Control
Directory of Open Access Journals (Sweden)
Yali Shen
2012-01-01
Full Text Available We study the permanence of a classofsingle species system with distributed time delay and feedback controls. General criteria on permanence are established in this paper. A very important fact is found in our results; that is, the feedback control is harmless to the permanence of species.
PTIDES: A Programming Model for Distributed Real-Time Embedded Systems
2008-05-28
following companies: Agilent, Bosch, HSBC , Lockheed-Martin, National Instruments, and Toyota. PTIDES: A Programming Model for Distributed Real-Time...companies: Agilent, Bosch, HSBC , Lockheed-Martin, National Instruments, and Toyota. expressed by threads. RTOSs and threads, however, pro- vide only
The influence of particle residence time distribution on the reactivity in fluidized bed reactors
Heesink, A.B.M.; Klaus, J.; Swaaij, van W.P.M.
1994-01-01
The influence of particle residence time distribution on the average conversion rate (or reactivity) of particles undergoing a non-catalytic gas-solid reaction inside a continuously operated fluidized bed reactor is evaluated. A so called ß-factor is defined as the ratio of the actual reactivity in
Miles, Syreeta L.; Sinclair, Ryan G.; Riley, Mark R; Pepper, Ian L
2011-01-01
This study evaluated real-time sensing of Escherichia coli as a microbial contaminant in water distribution systems. Most sensors responded to increased E. coli concentrations, showing that select sensors can detect microbial water quality changes and be utilized as part of a contaminant warning system.
Zieba, Bogumil; Sinderen, van Marten
2006-01-01
This paper addresses dynamic reconfiguration of distributed systems that use a publish/subscribe (pub/sub) middleware. The objective of dynamic reconfiguration is to evolve incrementally from one system configuration to another at run-time in order to e.g., ensure the reliability of the system. The
Confidence limits for the mean of exponential distribution in any time-sequential samples
Institute of Scientific and Technical Information of China (English)
CHEN Jiading; FANG Xiangzhong
2005-01-01
We present the general results determining confidence limits for the mean of exponential distribution in any time-sequential samples, which are obtained in any sequential life tests with replacement or without replacement. Especially, we give the best lower confidence limits in the case of no failure data.
Energy Technology Data Exchange (ETDEWEB)
Sievers, D.; Kuhn, E.; Tucker, M.; Stickel, J.; Wolfrum, E.
2013-06-01
Measurement and analysis of residence time distribution (RTD) data is the focus of this study where data collection methods were developed specifically for the pretreatment reactor environment. Augmented physical sampling and automated online detection methods were developed and applied. Both the measurement techniques themselves and the produced RTD data are presented and discussed.
Oudshoorn, F.W.; Kristensen, T.; Sharak Nadimi, I.
2008-01-01
The objective of this paper was to investigate the effect of limited grazing time on urination and defecation frequency, spatial distribution of excrement in the paddock, and the resulting nitrogen balance at animal and field level. During a 6-week period in early summer, 60 Holstein Frisian dairy
Dao Duc, Khanh; Parutto, Pierre; Chen, Xiaowei; Epsztein, Jérôme; Konnerth, Arthur; Holcman, David
2015-01-01
The dynamics of neuronal networks connected by synaptic dynamics can sustain long periods of depolarization that can last for hundreds of milliseconds such as Up states recorded during sleep or anesthesia. Yet the underlying mechanism driving these periods remain unclear. We show here within a mean-field model that the residence time of the neuronal membrane potential in cortical Up states does not follow a Poissonian law, but presents several peaks. Furthermore, the present modeling approach allows extracting some information about the neuronal network connectivity from the time distribution histogram. Based on a synaptic-depression model, we find that these peaks, that can be observed in histograms of patch-clamp recordings are not artifacts of electrophysiological measurements, but rather are an inherent property of the network dynamics. Analysis of the equations reveals a stable focus located close to the unstable limit cycle, delimiting a region that defines the Up state. The model further shows that the peaks observed in the Up state time distribution are due to winding around the focus before escaping from the basin of attraction. Finally, we use in vivo recordings of intracellular membrane potential and we recover from the peak distribution, some information about the network connectivity. We conclude that it is possible to recover the network connectivity from the distribution of times that the neuronal membrane voltage spends in Up states.
Directory of Open Access Journals (Sweden)
Khanh eDao Duc
2015-07-01
Full Text Available The dynamics of neuronal networks connected by synaptic dynamics can sustain long periods of depolarization that can last for hundreds of milliseconds such as Up states recorded during sleep or anesthesia. Yet the underlying mechanism driving these periods remain unclear. We show here within a mean-field model that the residence times of the neuronal membrane potential in cortical Up states does not follow a Poissonian law, but presents several peaks. Furthermore, the present modeling approach allows extracting some information about the neuronal network connectivity from the time distribution histogram. Based on a synaptic-depression model, we find that these peaks, that can be observed in histograms of patch-clamp recordings are not artifacts of electrophysiological measurements, but rather are an inherent property of the network dynamics. Analysis of the equations reveals a stable focus located close to the unstable limit cycle, delimiting a region that defines the Up state. The model further shows that the peaks observed in the Up state time distribution are due to winding around the focus before escaping from the basin of attraction. Finally, we use in vivo recordings of intracellular membrane potential and we recover from the peak distribution, some information about the network connectivity. We conclude that it is possible to recover the network connectivity from the distribution of times that the neuronal membrane voltage spends in Up states.
Analysis and Application of Distribution of Relaxation Times in Solid State Ionics
Boukamp, B.A.; Rolle, A.
2017-01-01
Three methods for obtaining a Distribution (Function) of Relaxation Times (DFRT) are compared, Fourier transform (FT), Tikhonov regularization (TR) and a multiple-(RQ) CNLS-fit. The FT method was written in the programming package ‘Borland Delphi’, for the Tikhonov regularization (TR) a freely avail
Zhang, Yanxiang; Chen, Yu; Li, Mei; Yan, Mufu; Ni, Meng; Xia, Changrong
2016-03-01
A new Tikhonov regularization approach without adjusting parameters is proposed for reconstructing distribution of relaxation time (DRT). It is capable of eliminating the pseudo peaks and capturing discontinuities in the DRT, making it feasible to resolve the number and the nature of electrochemical processes without making assumptions.
Chinese Climate and Vernacular Dwellings
Directory of Open Access Journals (Sweden)
Feifei Sun
2013-01-01
Full Text Available The industrial and economic expansion of China, particularly its rapid urbanization, has resulted in dramatic increased consumption of energy resources and the resulting environmental impacts at local, regional and global levels. Although a national program aimed at the technological development of sustainable buildings with energy saving potential is ongoing, it is also appropriate to consult vernacular architectural tradition. This holds the potential to learn and adapt important cultural ideas developed over time on the art of balancing thermal comfort between climate and limited resources. This paper explores the five different climatic regions into which China is partitioned by the Chinese authorities: severe cold region, cold region, moderate region, hot summer and cold winter region, and hot summer and mild winter region. Analysis of each region covers the climate and its vernacular architecture with a special focus on how sustainability was addressed. Finally, regional climate scenario has been analyzed on the basis of data from Meteonorm V6.1 with special attention paid to passive design strategies.
Generation of partially coherent stationary time histories with non-Gaussian distributions
Energy Technology Data Exchange (ETDEWEB)
Smallwood, D.O.
1996-08-27
In a previous paper Smallwood and Paez (1991) showed how to generate realizations of partially coherent stationary normal time histories with a specified cross-spectral density matrix. This procedure is generalized for the case of multiple inputs with a specified cross-spectral density function and a specified marginal probability density function (pdf) for each of the inputs. The specified pdfs are not required to be Gaussian. A zero memory nonlinear (ZMNL) function is developed for each input to transform a Gaussian or normal time history into a time history with a specified non-Gaussian distribution. The transformation functions have the property that a transformed time history will have nearly the same auto spectral density as the original time history. A vector of Gaussian time histories are then generated with the specified cross-spectral density matrix. These waveforms are then transformed into the required time history realizations using the ZMNL function.
Perks, M T; Warburton, J; Bracken, L J; Reaney, S M; Emery, S B; Hirst, S
2017-11-01
Under the EU Water Framework Directive, suspended sediment is omitted from environmental quality standards and compliance targets. This omission is partly explained by difficulties in assessing the complex dose-response of ecological communities. But equally, it is hindered by a lack of spatially distributed estimates of suspended sediment variability across catchments. In this paper, we demonstrate the inability of traditional, discrete sampling campaigns for assessing exposure to fine sediment. Sampling frequencies based on Environmental Quality Standard protocols, whilst reflecting typical manual sampling constraints, are unable to determine the magnitude of sediment exposure with an acceptable level of precision. Deviations from actual concentrations range between -35 and +20% based on the interquartile range of simulations. As an alternative, we assess the value of low-cost, suspended sediment sampling networks for quantifying suspended sediment transfer (SST). In this study of the 362 km(2) upland Esk catchment we observe that spatial patterns of sediment flux are consistent over the two year monitoring period across a network of 17 monitoring sites. This enables the key contributing sub-catchments of Butter Beck (SST: 1141 t km(2) yr(-1)) and Glaisdale Beck (SST: 841 t km(2) yr(-1)) to be identified. The time-integrated samplers offer a feasible alternative to traditional infrequent and discrete sampling approaches for assessing spatio-temporal changes in contamination. In conjunction with a spatially distributed diffuse pollution model (SCIMAP), time-integrated sediment sampling is an effective means of identifying critical sediment source areas in the catchment, which can better inform sediment management strategies for pollution prevention and control. Copyright © 2017 Elsevier Ltd. All rights reserved.
Analysis of distributed power control under constant and time-varying delays
Campos-delgado, Daniel U.; Luna-rivera, J. Martin; Bonilla, Isela
2013-10-01
This work studies the distributed power control algorithm proposed in 1993 by Foschini-Miljanic, standardised for universal mobile telecommunication systems. Continuous and discrete time versions of this algorithm are analysed. First, the stability of the distributed power allocation schemes was studied, where sufficient conditions to guarantee stability and convergence to a desired quality of service were provided. In this study, the channel gains are assumed to be slowly time-varying or piece-wise constant. For closed-loop control, a proportional controller is then employed under integral action in order to achieve good tracking despite time-varying and unknown channel gains. Next, the effects of constant and time-varying time delays in the closed-loop structure are studied. Explicit stability regions for the control gains in the Foschini-Miljanic scheme are derived for both the continuous and discrete-time versions of the algorithm, under constant and time-varying delays. For time-varying scenario, the resulting stability regions do not impose limitations on the rate change of the time-varying profiles. A comprehensive evaluation using simulations is performed to validate the analytical derivations described in the paper.
Sazuka, N
2006-01-01
We analyze waiting times for price changes in a foreign currency exchange rate. Recent empirical studies of high frequency financial data support that trades in financial markets do not follow a Poisson process and the waiting times between trades are not exponentially distributed. Here we show that our data is well approximated by a Weibull distribution rather than an exponential distribution in a non-asymptotic regime. Moreover, we quantitatively evaluate how much an empirical data is far from an exponential distribution using a Weibull fit. Finally, we discuss a phase transition between a Weibull-law and a power-law in the asymptotic long waiting time regime.
Estimating interevent time distributions from finite observation periods in communication networks.
Kivelä, Mikko; Porter, Mason A
2015-11-01
A diverse variety of processes-including recurrent disease episodes, neuron firing, and communication patterns among humans-can be described using interevent time (IET) distributions. Many such processes are ongoing, although event sequences are only available during a finite observation window. Because the observation time window is more likely to begin or end during long IETs than during short ones, the analysis of such data is susceptible to a bias induced by the finite observation period. In this paper, we illustrate how this length bias is born and how it can be corrected without assuming any particular shape for the IET distribution. To do this, we model event sequences using stationary renewal processes, and we formulate simple heuristics for determining the severity of the bias. To illustrate our results, we focus on the example of empirical communication networks, which are temporal networks that are constructed from communication events. The IET distributions of such systems guide efforts to build models of human behavior, and the variance of IETs is very important for estimating the spreading rate of information in networks of temporal interactions. We analyze several well-known data sets from the literature, and we find that the resulting bias can lead to systematic underestimates of the variance in the IET distributions and that correcting for the bias can lead to qualitatively different results for the tails of the IET distributions.
Distribution of Earthquake Interevent Times in Northeast India and Adjoining Regions
Pasari, Sumanta; Dikshit, Onkar
2015-10-01
This study analyzes earthquake interoccurrence times of northeast India and its vicinity from eleven probability distributions, namely exponential, Frechet, gamma, generalized exponential, inverse Gaussian, Levy, lognormal, Maxwell, Pareto, Rayleigh, and Weibull distributions. Parameters of these distributions are estimated from the method of maximum likelihood estimation, and their respective asymptotic variances as well as confidence bounds are calculated using Fisher information matrices. Three model selection criteria namely the Chi-square criterion, the maximum likelihood criterion, and the Kolmogorov-Smirnov minimum distance criterion are used to compare model suitability for the present earthquake catalog (Y adav et al. in Pure Appl Geophys 167:1331-1342, 2010). It is observed that gamma, generalized exponential, and Weibull distributions provide the best fitting, while exponential, Frechet, inverse Gaussian, and lognormal distributions provide intermediate fitting, and the rest, namely Levy, Maxwell Pareto, and Rayleigh distributions fit poorly to the present data. The conditional probabilities for a future earthquake and related conditional probability curves are presented towards the end of this article.
A novel time dependent gamma evaluation function for dynamic 2D and 3D dose distributions.
Podesta, Mark; Persoon, Lucas C G G; Verhaegen, Frank
2014-10-21
Modern external beam radiotherapy requires detailed verification and quality assurance so that confidence can be placed on both the delivery of a single treatment fraction and on the consistency of delivery throughout the treatment course. To verify dose distributions, a comparison between prediction and measurement must be made. Comparisons between two dose distributions are commonly performed using a Gamma evaluation which is a calculation of two quantities on a pixel by pixel basis; the dose difference, and the distance to agreement. By providing acceptance criteria (e.g. 3%, 3 mm), the function will find the most appropriate match within its two degrees of freedom. For complex dynamic treatments such as IMRT or VMAT it is important to verify the dose delivery in a time dependent manner and so a gamma evaluation that includes a degree of freedom in the time domain via a third parameter, time to agreement, is presented here. A C++ (mex) based gamma function was created that could be run on either CPU and GPU computing platforms that would allow a degree of freedom in the time domain. Simple test cases were created in both 2D and 3D comprising of simple geometrical shapes with well-defined boundaries varying over time. Changes of varying magnitude in either space or time were introduced and repeated gamma analyses were performed varying the criteria. A clinical VMAT case was also included, artificial air bubbles of varying size were introduced to a patient geometry, along with shifts of varying magnitude in treatment time. For all test cases where errors in distance, dose or time were introduced, the time dependent gamma evaluation could accurately highlight the errors.The time dependent gamma function presented here allows time to be included as a degree of freedom in gamma evaluations. The function allows for 2D and 3D data sets which are varying over time to be compared using appropriate criteria without penalising minor offsets of subsequent radiation fields
Localization of Dwell Fatigue Cracks in Ti-6242 Alloy Samples
Rokhlin, S. I.; Kim, J.-Y.; Xie, B.; Yakovlev, V. A.; Zoofan, B.
2003-03-01
An in-situ ultrasonic guided wave technique is employed for real-time monitoring of crack initiation and evolution during dwell, cyclic fatigue and creep tests of Ti-6242 alloy samples. Ultrasonic signals are acquired continuously during the test at different levels of fatigue load using a high-speed data acquisition system. The initiation time and growth history of primary and multiple secondary cracks are assessed. Localization of the secondary cracks is performed by both the in-situ ultrasonic method and an ultrasonic immersion scanning method which we call "vertical C-scan" (VC scan). The VC scan is developed for imaging small cracks aligned normal to the fatigue sample axis. The fusion of ultrasonic and microradiographic images exhibits good agreement in crack location. Joint use of the three techniques provides location, shape, and size of the secondary cracks.
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.
Discrete step model of helix-coil kinetics: Distribution of fluctuation times
Poland, Douglas
1996-07-01
A method is outlined for the computer simulation of the cooperative kinetics required to construct the distribution function for time intervals between fluctuations in conformational states in macromolecules. Using the helix-coil transition in polyamino acids as an example, we develop a Monte Carlo cellular automata approximation of the kinetics of this system in discrete time. This approximation is tested against a number of exact solutions for homopolymers and is then used to calculate moments of the distribution function for the time intervals between switches in conformational state at a given site (e.g., given a switch from coil to helix at zero time, how long will it take before the state switches back). The maximum-entropy method is used to construct the very broad distribution function from the moments. In heteropolymers the diffusion of helix-coil boundaries is reduced, helix being more localized on strong helix-forming residues. We investigate the effect of a specific sequence of amino acid residues on conformational fluctuations by using the known σ and s values for the naturally occurring amino acids to simulate the kinetics of helix formation (limiting the range of cooperativity to the α-helix) in sperm whale myoglobin, giving the time evolution to the equilibrium probability profile in this system.
DEFF Research Database (Denmark)
Støvring, Henrik; Pottegård, Anton; Hallas, Jesper
2017-01-01
Purpose: To introduce the reverse waiting time distribution (WTD) and show how it can be used to estimate stopping fractions and real-time prevalence of treatment in pharmacoepidemiological studies. Methods: The reverse WTD is the distribution of time from the last dispensed prescription of each ...
Sarang, Sanjay; Heskitt, Brian; Tulsiyan, Priyank; Sastry, Sudhir K
2009-08-01
The residence time distribution (RTD) of a model particulate-fluid mixture (potato in starch solution) in the ohmic heater in a continuous sterilization process was measured using a radio frequency identification (RFID) methodology. The effect of solid concentration and the rotational speed of the agitators on the RTD were studied. The velocity of the fastest particle was 1.62 times the mean product velocity. In general, particle velocity was found to be greater than the product bulk average velocity. Mean particle residence time (MPRT) increased with an increase in the rotational speed of the agitators (P < 0.05), and no particular trend was observed between the MPRT and the solid concentration. The distribution curves E (theta) were skewed to the right suggesting slow moving zones in the system.
From heavy-tailed to exponential distribution of interevent time in cellphone top-up behavior
Wang, Peng; Ma, Qiang
2017-05-01
Cellphone top-up is a kind of activities, to a great extent, driven by individual consumption rather than personal interest and this behavior should be stable in common sense. However, our researches find there are heavy-tails both in interevent time distribution and purchase frequency distribution at the global level. Moreover, we find both memories of interevent time and unit price series are negative, which is different from previous bursty activities. We divide individuals into five groups according to the purchase frequency and the average unit price respectively. Then, the group analysis shows some significant heterogeneity in this behavior. On one hand, we obtain only the individuals with high purchase frequency have the heavy-tailed nature in interevent time distribution. On the contrary, the negative memory is only caused by low purchase-frequency individuals without burstiness. On the other hand, the individuals with different preferential price also have different power-law exponents at the group level and there is no data collapse after rescaling between these distributions. Our findings produce the evidence for the significant heterogeneity of human activity in many aspects.
Modeling the time-periodicity of in-degree distributions in scientific citation networks
Liu, Qi; Xie, Zonglin; Dong, Enming; Li, Jianping
2016-01-01
In a range of citation networks, the in-degree distributions boast time-periodicity---the distributions of citations per article published each year present similar scale-free tails. This phenomenon can be regarded as a consequence of the emergence of hot topics and the existence of the "burst" phenomenon. With this inference considered, a geometric model based on our previous study is established, in which the sizes of the influence zones of nodes follow the same power-law distribution and decrease with their ages. The model successfully reproduces the time-periodicity of the in-degree distributions of the empirical data, and accounts for the presence of citation burst as well. Moreover, a reasonable explanation for the emergence of the scale-free tails by regarding the citation behavior between articles as a "yes/no" experiment is presented. The model can also predict the time-periodicity of the local clustering coefficients, which indicates that the model is a good tool in researches on the evolutionary me...
Time evolution analysis of the electron distribution in Thomson/Compton back-scattering
Energy Technology Data Exchange (ETDEWEB)
Petrillo, V.; Bacci, A.; Curatolo, C.; Maroli, C.; Serafini, L.; Rossi, A. R. [INFN-Universitá degli Studi Milano, Via Celoria, 16 20133 Milano (Italy)
2013-07-28
We present the time evolution of the energy distribution of a relativistic electron beam after the Compton back-scattering with a counter-propagating laser field, performed in the framework of the Quantum Electrodynamics, by means of the code CAIN. As the correct angular distribution of the spontaneous emission is accounted, the main effect is the formation of few stripes, followed by the diffusion of the more energetic particles toward lower values in the longitudinal phase space. The Chapman-Kolmogorov master equation gives results in striking agreement with the numerical ones. An experiment on the Thomson source at SPARC-LAB is proposed.
Time evolution analysis of the electron distribution in Thomson/Compton back-scattering
Petrillo, V.; Bacci, A.; Curatolo, C.; Maroli, C.; Serafini, L.; Rossi, A. R.
2013-07-01
We present the time evolution of the energy distribution of a relativistic electron beam after the Compton back-scattering with a counter-propagating laser field, performed in the framework of the Quantum Electrodynamics, by means of the code CAIN. As the correct angular distribution of the spontaneous emission is accounted, the main effect is the formation of few stripes, followed by the diffusion of the more energetic particles toward lower values in the longitudinal phase space. The Chapman-Kolmogorov master equation gives results in striking agreement with the numerical ones. An experiment on the Thomson source at SPARC-LAB is proposed.
DEFF Research Database (Denmark)
Tjell, Simon; Fernandes, João Miguel
2008-01-01
In a distributed embedded system, it is often necessary to share variables among its computing nodes to allow the distribution of control algorithms. It is therefore necessary to include a component in each node that provides the service of variable sharing. For that type of component, this paper...... discusses how to create a Colored Petri Nets (CPN) model that formally expresses the following elements in a clearly separated structure: (1) assumptions about the behavior of the environment of the component, (2) real-time requirements for the component, and (3) a possible solution in terms of an algorithm...
Distributed hot-wire anemometry based on Brillouin optical time-domain analysis.
Wylie, Michael T V; Brown, Anthony W; Colpitts, Bruce G
2012-07-02
A distributed hot-wire anemometer based on Brillouin optical time-domain analysis is presented. The anemometer is created by passing a current through a stainless steel tube fibre bundle and monitoring Brillouin frequency changes in the presence of airflow. A wind tunnel is used to provide laminar airflow while the device response is calibrated against theoretical models. The sensitivity equation for this anemometer is derived and discussed. Airspeeds from 0 m/s to 10 m/s are examined, and the results show that a Brillouin scattering based distributed hot-wire anemometer is feasible.
A FEMTOSECOND-LEVEL FIBER-OPTICS TIMING DISTRIBUTION SYSTEM USING FREQUENCY-OFFSET INTERFEROMETRY
Energy Technology Data Exchange (ETDEWEB)
Staples, J.W.; Byrd, J.; Doolittle, L.; Huang, G.; Wilcox, R.
2009-10-17
An optical fiber-based frequency and timing distribution system based on the principle of heterodyne interferometry has been in development at LBNL for several years. The fiber drift corrector has evolved from an RF-based to an optical-based system, from mechanical correctors (piezo and optical trombone) to fully electronic, and the electronics from analog to fully digital, all using inexpensive off-the-shelf commodity fiber components. Short-term optical phase jitter and long-term phase drift are both in the femtosecond range over distribution paths of 2 km or more.
Experimental Study on Practical Quantum Key Distribution Scheme with Time-Multiplexed Technique
Institute of Scientific and Technical Information of China (English)
HUANG Yu-Xian; HU Hua-Peng; LIANG Rui-Sheng; LU Yi-Qun; WANG Jin-Dong; LU Wei
2008-01-01
We present a scheme that is capable of detecting photon numbers during the quantum key distribution (QKD) based on an improved differential phase shift (DPS) system without Trojan horse attack. A time-multiplexed detector (TMD) is set in for the photon-number resolution. Two fibre loops are used for detecting photon numbers as well as distributing keys. The long-term stabilization is guaranteed by two Faraday mirrors (FM) at Bob's site to automatically compensate for polarization defect. Our experimental study (90km QKD is completed) indicates that such a system is stable and secure which nearly reaches the performance of a single photon scheme.
Directory of Open Access Journals (Sweden)
Gang Xiong
2009-01-01
Full Text Available This paper presents theoretical results on the convergence of the distributed consensus timing synchronization (DCTS algorithm for wireless sensor networks assuming general Gaussian delay between nodes. The asymptotic expectation and mean square of the global synchronization error are computed. The results lead to the definition of a time delay balanced network in which average timing consensus between nodes can be achieved despite random delays. Several structured network architectures are studied as examples, and their associated simulation results are used to validate analytical findings.
Validated Real Time Middle Ware For Distributed Cyber Physical Systems Using Hmm(
Directory of Open Access Journals (Sweden)
Ankit Mundra
2013-04-01
Full Text Available Distributed Cyber Physical Systems designed for different scenario must be capable enough to perform inan efficient manner in every situation. Earlier approaches, such as CORBA, has performed but withdifferent time constraints. Therefore, there was the need to design reconfigurable, robust, validated andconsistent real time middle ware systems with end-to-end timing. In the DCPS-HMM we have proposed theprocessor efficiency and data validation which may proof crucial in implementing various distributedsystems such as credit card systems or file transfer through network.
Extracting message inter-departure time distributions from the human electroencephalogram.
Directory of Open Access Journals (Sweden)
Bratislav Mišić
2011-06-01
Full Text Available The complex connectivity of the cerebral cortex is a topic of much study, yet the link between structure and function is still unclear. The processing capacity and throughput of information at individual brain regions remains an open question and one that could potentially bridge these two aspects of neural organization. The rate at which information is emitted from different nodes in the network and how this output process changes under different external conditions are general questions that are not unique to neuroscience, but are of interest in multiple classes of telecommunication networks. In the present study we show how some of these questions may be addressed using tools from telecommunications research. An important system statistic for modeling and performance evaluation of distributed communication systems is the time between successive departures of units of information at each node in the network. We describe a method to extract and fully characterize the distribution of such inter-departure times from the resting-state electroencephalogram (EEG. We show that inter-departure times are well fitted by the two-parameter Gamma distribution. Moreover, they are not spatially or neurophysiologically trivial and instead are regionally specific and sensitive to the presence of sensory input. In both the eyes-closed and eyes-open conditions, inter-departure time distributions were more dispersed over posterior parietal channels, close to regions which are known to have the most dense structural connectivity. The biggest differences between the two conditions were observed at occipital sites, where inter-departure times were significantly more variable in the eyes-open condition. Together, these results suggest that message departure times are indicative of network traffic and capture a novel facet of neural activity.
Hubig, Michael; Muggenthaler, Holger; Mall, Gita
2014-05-01
Bayesian estimation applied to temperature based death time estimation was recently introduced as conditional probability distribution or CPD-method by Biermann and Potente. The CPD-method is useful, if there is external information that sets the boundaries of the true death time interval (victim last seen alive and found dead). CPD allows computation of probabilities for small time intervals of interest (e.g. no-alibi intervals of suspects) within the large true death time interval. In the light of the importance of the CPD for conviction or acquittal of suspects the present study identifies a potential error source. Deviations in death time estimates will cause errors in the CPD-computed probabilities. We derive formulae to quantify the CPD error as a function of input error. Moreover we observed the paradox, that in cases, in which the small no-alibi time interval is located at the boundary of the true death time interval, adjacent to the erroneous death time estimate, CPD-computed probabilities for that small no-alibi interval will increase with increasing input deviation, else the CPD-computed probabilities will decrease. We therefore advise not to use CPD if there is an indication of an error or a contra-empirical deviation in the death time estimates, that is especially, if the death time estimates fall out of the true death time interval, even if the 95%-confidence intervals of the estimate still overlap the true death time interval.
The rates and time-delay distribution of multiply imaged supernovae behind lensing clusters
Energy Technology Data Exchange (ETDEWEB)
Li, Xue; Hjorth, Jens [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100, Copenhagen (Denmark); Richard, Johan, E-mail: lixue@dark-cosmology.dk, E-mail: jens@dark-cosmology.dk, E-mail: johan.richard@univ-lyon1.fr [CRAL, Observatoire de Lyon, Université Lyon 1, 9 Avenue Ch. André, 69561 Saint Genis Laval Cedex (France)
2012-11-01
Time delays of gravitationally lensed sources can be used to constrain the mass model of a deflector and determine cosmological parameters. We here present an analysis of the time-delay distribution of multiply imaged sources behind 17 strong lensing galaxy clusters with well-calibrated mass models. We find that for time delays less than 1000 days, at z = 3.0, their logarithmic probability distribution functions are well represented by P(log Δt) = 5.3 × 10{sup −4}Δt{sup β-tilde}/M{sub 250}{sup 2β-tilde}, with β-tilde = 0.77, where M{sub 250} is the projected cluster mass inside 250 kpc (in 10{sup 14}M{sub ☉}), and β-tilde is the power-law slope of the distribution. The resultant probability distribution function enables us to estimate the time-delay distribution in a lensing cluster of known mass. For a cluster with M{sub 250} = 2 × 10{sup 14}M{sub ☉}, the fraction of time delays less than 1000 days is approximately 3%. Taking Abell 1689 as an example, its dark halo and brightest galaxies, with central velocity dispersions σ≥500kms{sup −1}, mainly produce large time delays, while galaxy-scale mass clumps are responsible for generating smaller time delays. We estimate the probability of observing multiple images of a supernova in the known images of Abell 1689. A two-component model of estimating the supernova rate is applied in this work. For a magnitude threshold of m{sub AB} = 26.5, the yearly rate of Type Ia (core-collapse) supernovae with time delays less than 1000 days is 0.004±0.002 (0.029±0.001). If the magnitude threshold is lowered to m{sub AB} ∼ 27.0, the rate of core-collapse supernovae suitable for time delay observation is 0.044±0.015 per year.
Danesh-Yazdi, Mohammad; Foufoula-Georgiou, Efi; Karwan, Diana L.; Botter, Gianluca
2016-10-01
Climatic trends and anthropogenic changes in land cover and land use are impacting the hydrology and water quality of streams at the field, watershed, and regional scales in complex ways. In poorly drained agricultural landscapes, subsurface drainage systems have been successful in increasing crop productivity by removing excess soil moisture. However, their hydroecological consequences are still debated in view of the observed increased concentrations of nitrate, phosphorus, and pesticides in many streams, as well as altered runoff volumes and timing. In this study, we employ the recently developed theory of time-variant travel time distributions within the StorAge Selection function framework to quantify changes in water cycle dynamics resulting from the combined climate and land use changes. Our results from analysis of a subbasin in the Minnesota River Basin indicate a significant decrease in the mean travel time of water in the shallow subsurface layer during the growing season under current conditions compared to the pre-1970s conditions. We also find highly damped year-to-year fluctuations in the mean travel time, which we attribute to the "homogenization" of the hydrologic response due to artificial drainage. The dependence of the mean travel time on the spatial heterogeneity of some soil characteristics as well as on the basin scale is further explored via numerical experiments. Simulations indicate that the mean travel time is independent of scale for spatial scales larger than approximately 200 km2, suggesting that hydrologic data from larger basins may be used to infer the average of smaller-scale-driven changes in water cycle dynamics.
Peralta-Tapia, A.; Soulsby, C.; Tetzlaff, D.; Sponseller, R.; Bishop, K.; Laudon, H.
2016-12-01
Understanding how water moves through catchments - from the time it enters as precipitation to when it exits via streamflow - is of fundamental importance to understanding hydrological and biogeochemical processes. A basic descriptor of this routing is the Transit Time Distribution (TTD) which is derived from the input-output behavior of conservative tracers, the mean of which represents the average time elapsed between water molecules entering and exiting a flow system. In recent decades, many transit time studies have been conducted, but few of these have focused on snow-dominated catchments. We assembled a 10-year time series of isotopic data (δ18O and δ2H) for precipitation and stream water to estimate the characteristics of the transit time distribution in a boreal catchment in northern Sweden. We applied lumped parameter models using a gamma distribution to calculate the Mean Transit Time (MTT) of water over the entire period of record and to evaluate how inter-annual differences in transit times relate to hydroclimatic variability. The best fit MTT for the complete 10-year period was 650 days (Nash-Sutcliff Efficiency = 0.65), while the best fit inter-annual MTT ranged from 300 days up to 1200 days. Whilst there was a weak negative correlation between mean annual total precipitation and the annual MTT, this relationship was stronger (r2 = 0.53, p = 0.02) for the annual rain water input. This strong connection between the MTT and annual rainfall, rather than snowmelt, has strong implications for understanding future hydrological and biogeochemical processes in boreal regions, given that predicted warmer winters would translate into a greater proportion of precipitation falling as rain and thus shorter MTT in catchments. Such a change could have direct implications for the export of solutes and pollutants.
Modelling window opening behaviour in Danish dwellings
DEFF Research Database (Denmark)
Andersen, Rune Vinther; Olesen, Bjarne W.; Toftum, Jørn
2011-01-01
In this paper we present and analyse data from two studies of window opening behaviour in residential buildings in Denmark. Based on measurements of indoor environment, weather and window opening behaviour in 15 dwellings, we propose a model that will predict window opening behaviour. The data...... showed that other factors than thermal effects impact the behaviour of the occupants. Some of these factors were included in the model. We present data from repeated questionnaire surveys that show that occupants tend to adjust heating setpoints, adjust clothing and operate windows when feeling thermally...
Toward an improved distribution approach for real-time data sharing
Chayes, D. N.; Arko, R. A.; Roberts, S. D.
2009-12-01
Our shipboard data systems have been using UDP/IP broadcast datagrams for distributing real-time underway data starting on the R/V Conrad in 1987 and expanding to include the Ewing, Palmer, Gould, Healy and Langseth among others. This approach has many advantages including: ease of implementation; simplicity; and isolation of the clients from the real-time loggers. A number of other shipboard data systems have successfully adopted this approach. In the modern era of nearly full-time Internet connectivity for the research fleet, the ability to distribute near-real-time data to shore sites is expanding rapidly and should be done efficiently. For example, the NSF-supported Rolling Deck to Repository (R2R) and Shipboard Automated Meteorological and Oceanographic System (SAMOS) projects are jointly developing a new protocol to transfer high-frequency meteorological and surface oceanographic data from fleet vessels to a shore server for monitoring and quality control. At the same time, we are finding more sophisticated uses for real-time data at sea in addition to our own need to automate on-board real-time data quality checking. In order to facilitate these needs, we are developing a plan to migrate our data system to Multicast datagrams and add an open, standards-based discovery service so that clients connecting to our shipboard network can automatically find and use our data streams.
Storm-Time Evolution of Energetic Electron Pitch Angle Distributions by Wave-Particle Interaction
Institute of Scientific and Technical Information of China (English)
XIAO Fuliang; HE Huiyong; ZHOU Qinghua; WU Guanhong; SHI Xianghua
2008-01-01
The quasi-pure pitch-angle scattering of energetic electrons driven by field-alignedpropagating whistler mode waves during the 9～15 October 1990 magnetic storm at L ≈ 3 ～ 4 is studied, and numerical calculations for energetic electrons in gyroresonance with a band of frequency of whistler mode waves distributed over a standard Gaussian spectrum is performed. It is found that the whistler.mode waves can efficiently drive energetic electrons from the larger pitch-angles into the loss cone, and lead to a flat-top distribution during the main phase of geomagnetic storms. This result perhaps presents a feasible interpretation for observation of time evolution of the quasi-isotropic pitch-angle distribution by Combined Release and Radiation Effects Satellite (CRRES) spacecraft at L ≈ 3 ～ 4.
Interevent time distributions of human multi-level activity in a virtual world
Mryglod, O.; Fuchs, B.; Szell, M.; Holovatch, Yu.; Thurner, S.
2015-02-01
Studying human behavior in virtual environments provides extraordinary opportunities for a quantitative analysis of social phenomena with levels of accuracy that approach those of the natural sciences. In this paper we use records of player activities in the massive multiplayer online game Pardus over 1238 consecutive days, and analyze dynamical features of sequences of actions of players. We build on previous work where temporal structures of human actions of the same type were quantified, and provide an empirical understanding of human actions of different types. This study of multi-level human activity can be seen as a dynamic counterpart of static multiplex network analysis. We show that the interevent time distributions of actions in the Pardus universe follow highly non-trivial distribution functions, from which we extract action-type specific characteristic 'decay constants'. We discuss characteristic features of interevent time distributions, including periodic patterns on different time scales, bursty dynamics, and various functional forms on different time scales. We comment on gender differences of players in emotional actions, and find that while males and females act similarly when performing some positive actions, females are slightly faster for negative actions. We also observe effects on the age of players: more experienced players are generally faster in making decisions about engaging in and terminating enmity and friendship, respectively.
Kumar, Ashish; Vercruysse, Jurgen; Vanhoorne, Valérie; Toiviainen, Maunu; Panouillot, Pierre-Emmanuel; Juuti, Mikko; Vervaet, Chris; Remon, Jean Paul; Gernaey, Krist V; De Beer, Thomas; Nopens, Ingmar
2015-04-25
Twin-screw granulation is a promising continuous alternative for traditional batchwise wet granulation processes. The twin-screw granulator (TSG) screws consist of transport and kneading element modules. Therefore, the granulation to a large extent is governed by the residence time distribution within each module where different granulation rate processes dominate over others. Currently, experimental data is used to determine the residence time distributions. In this study, a conceptual model based on classical chemical engineering methods is proposed to better understand and simulate the residence time distribution in a TSG. The experimental data were compared with the proposed most suitable conceptual model to estimate the parameters of the model and to analyse and predict the effects of changes in number of kneading discs and their stagger angle, screw speed and powder feed rate on residence time. The study established that the kneading block in the screw configuration acts as a plug-flow zone inside the granulator. Furthermore, it was found that a balance between the throughput force and conveying rate is required to obtain a good axial mixing inside the twin-screw granulator. Although the granulation behaviour is different for other excipients, the experimental data collection and modelling methods applied in this study are generic and can be adapted to other excipients.
Directory of Open Access Journals (Sweden)
B. M. Khroustalev
2011-01-01
Full Text Available The variant of efficient combination of two renewable energy sources as a biogas system and a water heating solar system has been considered for power supply of individual dwellings. Criteria dependence has been suggested for determination of solar system power efficiency. Its legitimacy has been proved by an experiment. Power efficient solar system has been proposed with peculiar features of its designing and due account of energy flow distribution in technology of biogas production.
Estimating the flood frequency distribution at seasonal and annual time scales
Directory of Open Access Journals (Sweden)
E. Baratti
2012-12-01
Full Text Available We propose an original approach to infer the flood frequency distribution at seasonal and annual time scale. Our purpose is to estimate the peak flow that is expected for an assigned return period T, independently of the season in which it occurs (i.e. annual flood frequency regime, as well as in different selected sub-yearly periods (i.e. seasonal flood frequency regime. While a huge literature exists on annual flood frequency analysis, few studies have focused on the estimation of seasonal flood frequencies despite the relevance of the issue, for instance when scheduling along the months of the year the construction phases of river engineering works directly interacting with the active river bed, like for instance dams. An approximate method for joint frequency analysis is presented here that guarantees consistency between fitted annual and seasonal distributions, i.e. the annual cumulative distribution is the product of the seasonal cumulative distribution functions, under the assumption of independence among floods in different seasons. In our method the parameters of the seasonal frequency distributions are fitted by maximising an objective function that accounts for the likelihoods of both seasonal and annual peaks. In contrast to previous studies, our procedure is conceived to allow the users to introduce subjective weights to the components of the objective function in order to emphasize the fitting of specific seasons or of the annual peak flow distribution. An application to the time series of the Blue Nile daily flows at the Sudan–Ethiopia border is presented.
Design optimization of TTEthernet-based distributed real-time systems
DEFF Research Database (Denmark)
Tamas-Selicean, Domitian; Pop, Paul; Steiner, Wilfried
2015-01-01
Many safety-critical real-time applications are implemented using distributed architectures, composed of heterogeneous processing elements interconnected in a network. Our focus in this paper is on the TTEthernet protocol, a deterministic, synchronized and congestion-free network protocol based...... on the Ethernet standard and compliant with the ARINC 664 Specification Part 7. TTEthernet is highly suitable for safety-critical real-time applications since it offers separation for messages using the concept of virtual links and supports three time-criticality classes: Time-Triggered (TT), Rate-Constrained (RC......) and Best-Effort. In this paper we are interested in the design optimization of TTEthernet networks used to transmit real-time application messages. Given the set of TT and RC messages, and the topology of the network, our approach optimizes the packing of messages in frames, the assignment of frames...
The first-passage time distribution for the diffusion model with variable drift
DEFF Research Database (Denmark)
Blurton, Steven Paul; Kesselmeier, Miriam; Gondan, Matthias
2017-01-01
The Ratcliff diffusion model is now arguably the most widely applied model for response time data. Its major advantage is its description of both response times and the probabilities for correct as well as incorrect responses. The model assumes a Wiener process with drift between two constant...... absorbing barriers. The first-passage times at the upper and lower boundary describe the responses in simple two-choice decision tasks, for example, in experiments with perceptual discrimination or memory search. In applications of the model, a usual assumption is a varying drift of the Wiener process...... across trials. This extra flexibility allows accounting for slow errors that often occur in response time experiments. So far, the predicted response time distributions were obtained by numerical evaluation as analytical solutions were not available. Here, we present an analytical expression...
Choice Overload, Satisficing Behavior, and Price Distribution in a Time Allocation Model
Directory of Open Access Journals (Sweden)
Francisco Álvarez
2014-01-01
Full Text Available Recent psychological research indicates that consumers that search exhaustively for the best option of a market product—known as maximizers—eventually feel worse than consumers who just look for something good enough—called satisficers. We formulate a time allocation model to explore the relationship between different distributions of prices of the product and the satisficing behavior and the related welfare of the consumer. We show numerically that, as the number of options becomes large, the maximizing behavior produces less and less welfare and eventually leads to choice paralysis—these are effects of choice overload—whereas satisficing conducts entail higher levels of satisfaction and do not end up in paralysis. For different price distributions, we provide consistent evidence that maximizers are better off for a low number of options, whereas satisficers are better off for a sufficiently large number of options. We also show how the optimal satisficing behavior is affected when the underlying price distribution varies. We provide evidence that the mean and the dispersion of a symmetric distribution of prices—but not the shape of the distribution—condition the satisficing behavior of consumers. We also show that this need not be the case for asymmetric distributions.
Conceptual framework for distributed expert-system use in time-sensitive hierarchical control
Energy Technology Data Exchange (ETDEWEB)
Henningsen, J.R.
1987-01-01
There are many problems faced by decision makers involved in complex, time-sensitive hierarchical control systems. These may include maintaining knowledge of the functional status of the system components, forecasting the impact of past and future events, transferring information to a distant or poorly connected location, changing the requirements for an operation according to resources available, or creating an independent course of action when system connectivity falls. These problems are transdisciplinary in nature, so decision makers in a variety of organizations face them. This research develops a framework for the use of distributed expert systems in support of time-sensitive hierarchical control systems. Attention is focused on determining ways to enhance the likelihood that a system will remain functional during a crisis in which one or more of the system nodes fail. Options in the use of distributed expert systems for this purpose are developed following investigation of related research in the areas of cooperative and distributed systems. A prototype under development of a generic system model called DES (distributed expert systems) is described. DES is a trimular form of support structure, where a trimule is defined to be a combination of a human decision agent, a component system model and an expert system. This concept is an extension of the domular theory of Tenney and Sandell (1981).
Geographic characteristics of sable (Martes zibellina) distribution over time in Northeast China.
Zhang, Rui; Yang, Li; Ai, Lin; Yang, Qiuyuan; Chen, Minhao; Li, Jingxi; Yang, Lei; Luan, Xiaofeng
2017-06-01
Understanding historical context can help clarify the ecological and biogeographic characteristics of species population changes. The sable (Martes zibellina) population has decreased dramatically in Northeast China since the l950s, and understanding the changes in its distribution over time is necessary to support conservation efforts. To achieve this goal, we integrated ecological niche modeling and historical records of sables to estimate the magnitude of change in their distribution over time. Our results revealed a 51.71% reduction in their distribution in 2000-2016 compared with the potential distribution in the 1950s. This reduction was related to climate change (Pearson's correlation: Bio1, -.962, p areas due to climate change: In the Greater Khingan Mountains, they moved northward and to lower elevations; in the Lesser Khingan Mountains, they moved northward; and in the Changbai Mountains, they move southward and to higher elevations. Active conservation strategies should be considered in locations where sable populations have migrated or may migrate to.
Fertility Heterogeneity as a Mechanism for Power Law Distributions of Recurrence Times
Saichev, A
2012-01-01
We study the statistical properties of recurrence times in the self-excited Hawkes conditional Poisson process, the simplest extension of the Poisson process that takes into account how the past events influence the occurrence of future events. Specifically, we analyze the impact of the power law distribution of fertilities with exponent \\alpha, where the fertility of an event is the number of aftershocks of first generation that it triggers, on the probability distribution function (pdf) f(\\tau) of the recurrence times \\tau between successive events. The other input of the model is an exponential Omori law quantifying the pdf of waiting times between an event and its first generation aftershocks, whose characteristic time scale is taken as our time unit. At short time scales, we discover two intermediate power law asymptotics, f(\\tau) ~ \\tau^{-(2-\\alpha)} for \\tau << \\tau_c and f(\\tau) ~ \\tau^{-\\alpha} for \\tau_c << \\tau << 1, where \\tau_c is associated with the self-excited cascades of aft...
Marginal estimation for multi-stage models: waiting time distributions and competing risks analyses.
Satten, Glen A; Datta, Somnath
2002-01-15
We provide non-parametric estimates of the marginal cumulative distribution of stage occupation times (waiting times) and non-parametric estimates of marginal cumulative incidence function (proportion of persons who leave stage j for stage j' within time t of entering stage j) using right-censored data from a multi-stage model. We allow for stage and path dependent censoring where the censoring hazard for an individual may depend on his or her natural covariate history such as the collection of stages visited before the current stage and their occupation times. Additional external time dependent covariates that may induce dependent censoring can also be incorporated into our estimates, if available. Our approach requires modelling the censoring hazard so that an estimate of the integrated censoring hazard can be used in constructing the estimates of the waiting times distributions. For this purpose, we propose the use of an additive hazard model which results in very flexible (robust) estimates. Examples based on data from burn patients and simulated data with tracking are also provided to demonstrate the performance of our estimators.
Janssen, Paddy K.C.
2016-01-01
Purpose To find the most accurate mathematical description of the intravaginal ejaculation latency time (IELT) distribution in the general male population. Materials and Methods We compared the fitness of various well-known mathematical distributions with the IELT distribution of two previously published stopwatch studies of the Caucasian general male population and a stopwatch study of Dutch Caucasian men with lifelong premature ejaculation (PE). The accuracy of fitness is expressed by the Goodness of Fit (GOF). The smaller the GOF, the more accurate is the fitness. Results The 3 IELT distributions are gamma distributions, but the IELT distribution of lifelong PE is another gamma distribution than the IELT distribution of men in the general male population. The Lognormal distribution of the gamma distributions most accurately fits the IELT distribution of 965 men in the general population, with a GOF of 0.057. The Gumbel Max distribution most accurately fits the IELT distribution of 110 men with lifelong PE with a GOF of 0.179. There are more men with lifelong PE ejaculating within 30 and 60 seconds than can be extrapolated from the probability density curve of the Lognormal IELT distribution of men in the general population. Conclusions Men with lifelong PE have a distinct IELT distribution, e.g., a Gumbel Max IELT distribution, that can only be retrieved from the general male population Lognormal IELT distribution when thousands of men would participate in a IELT stopwatch study. The mathematical formula of the Lognormal IELT distribution is useful for epidemiological research of the IELT. PMID:26981594
Ventilation, indoor air quality, and human health and comfort in dwellings and day-care centers
Energy Technology Data Exchange (ETDEWEB)
Ruotsalainen, R.
1995-12-31
The objective of the study was to assess the actual ventilation and indoor air quality in the Finnish building stock (dwellings and day-care centers) with special reference to the existing guideline values. Furthermore, the objective was to evaluate the occurrence of symptoms and perceptions among occupants (adult residents, children, workers) in relation to ventilation system, ventilation rate and dampness. The measurements of ventilation and indoor air quality in the dwellings and day-care centers included ventilation rate, CO{sub 2} concentration, and temperature and humidity. Self- and parent-administered questionnaires were distributed to the occupants inquiring their personal characteristics, occurrence of symptoms of interest, perceived indoor air quality and details of their home and work environments. Airflows and air change rates varied remarkably both in the dwellings and day-care centers. In the majority of the dwellings and day-care centers, the Finnish guideline values of ventilation rates were not achieved. No consistent associations were observed between the magnitude of mechanical ventilation rates and the occurrence of eye, respiratory, skin and general symptoms, that is, symptoms of sick building syndrome (SBS) among the day-care workers. The results indicate that there is much room for improvement in the ventilation and indoor air quality of Finnish dwellings and day-care centers. The control of ventilation, temperature and humidity and the prevention of water damage are important issues on which to concentrate in the future. There is need to improve the quality in all phases of construction: design, installation, adjustment, operation, and maintenance
Source distribution of ocean microseisms and implications for time-dependent noise tomography
Kedar, Sharon
2011-09-01
A qualitative analysis of ocean microseism source distribution observed in North America during fall and winter months was carried out. I review the theory of the origin of ocean microseisms and show that it can be used in conjunction with wave-wave interaction maps to quantify the source distribution anisotropy. It is demonstrated that microseisms generation in the North Atlantic and in the North Pacific Oceans are inherently different. North Atlantic microseisms are generated predominantly in the deep ocean, while North Pacific microseisms are dominated by coastal reflections. In spite of these differences both result from repeated ocean wave patterns that give rise to an anisotropic noise pattern, which cannot be randomized by time averaging. Considering time-varying ambient noise imaging, which aims to resolve a fraction of a percent changes in the crust over short distances, the source anisotropy would introduce a relatively significant error that needs to be accounted for.
Design of Mixed-Criticality Applications on Distributed Real-Time Systems
DEFF Research Database (Denmark)
Tamas-Selicean, Domitian
the concept of virtual links, and temporal separation, enforced through schedule tables for TT messages and bandwidth allocation for RC messages. The objective of this thesis is to develop methods and tools for distributed mixed-criticality real-time systems. At the processor level, we are interested......A mixed-criticality system implements applications of different safety-criticality levels onto the same platform. In such cases, the certification standards require that applications of different criticality levels are protected so they cannot influence each other. Otherwise, all tasks have...... to be developed and certified according to the highest criticality level, dramatically increasing the development costs. In this thesis we consider mixed-criticality real-time applications implemented on distributed partitioned architectures. Partitioned architectures use temporal and spatial separation...
Institute of Scientific and Technical Information of China (English)
CHEN; Jiawei; YANG; Mu; FENG; Haibao; NI; Qijun
2016-01-01
The real-time retrieval of submicron aerosol size distributions is of major interest for applications. Based on the Mie theory,the spectral extinction method offers a simple measurement principle and a convenient optical arrangement. In contrast to the relative simplicity of the experimental measurement the retrieval of the particles size distribution and particle concentration from the spectral extinction method is difficult. Mie scattering Equation is a Fredholm Integral Equation of the First Kind. This paper develops a hybrid iterative model-dependent algorithm for on-line particle sizing from extinction spectra which is both computationally efficient and accurate. Applying the refined Mie diagnostic iterative procedures within some candidate solutions can identify the unique result accurately and rapidly enough for real time measurement. With the addition of added Gaussian noise,an average tolerance up to 5% of noise level is kept for particle size from submicron to micrometer under moderate polydispersity.
An approach to experimental evaluation of real-time fault-tolerant distributed computing schemes
Kim, K. H.
1989-01-01
A testbed-based approach to the evaluation of fault-tolerant distributed computing schemes is discussed. The approach is based on experimental incorporation of system structuring and design techniques into real-time distributed-computing testbeds centered around tightly coupled microcomputer networks. The effectiveness of this approach has been experimentally confirmed. Primary advantages of this approach include the accuracy of the timing and logical-complexity data and the degree of assurance of the practical effectiveness of the scheme evaluated. Various design issues encountered in the course of establishing the network testbed facilities are discussed, along with their augmentation to support some experiments. The shortcomings of the testbeds are also discussed together with the desired extensions of the testbeds.
Weakest-Link Scaling and Finite Size Effects on Recurrence Times Distribution
Hristopulos, Dionissios T; Kaniadakis, Giorgio
2013-01-01
Tectonic earthquakes result from the fracturing of the Earth's crust due to the loading induced by the motion of the tectonic plates. Hence, the statistical laws of earthquakes must be intimately connected to the statistical laws of fracture. The Weibull distribution is a commonly used model of earthquake recurrence times (ERT). Nevertheless, deviations from Weibull scaling have been observed in ERT data and in fracture experiments on quasi-brittle materials. We propose that the weakest-link-scaling theory for finite-size systems leads to the kappa-Weibull function, which implies a power-law tail for the ERT distribution. We show that the ERT hazard rate function decreases linearly after a waiting time which is proportional to the system size (in terms of representative volume elements) raised to the inverse of the Weibull modulus. We also demonstrate that the kappa-Weibull can be applied to strongly correlated systems by means of simulations of a fiber bundle model.
Decentralized Observer with a Consensus Filter for Distributed Discrete-Time Linear Systems
Acikmese, Behcet; Mandic, Milan
2011-01-01
This paper presents a decentralized observer with a consensus filter for the state observation of a discrete-time linear distributed systems. In this setup, each agent in the distributed system has an observer with a model of the plant that utilizes the set of locally available measurements, which may not make the full plant state detectable. This lack of detectability is overcome by utilizing a consensus filter that blends the state estimate of each agent with its neighbors' estimates. We assume that the communication graph is connected for all times as well as the sensing graph. It is proven that the state estimates of the proposed observer asymptotically converge to the actual plant states under arbitrarily changing, but connected, communication and sensing topologies. As a byproduct of this research, we also obtained a result on the location of eigenvalues, the spectrum, of the Laplacian for a family of graphs with self-loops.
Estimating inter-event time distributions from finite observation periods in communication networks
Kivelä, Mikko
2014-01-01
A diverse variety of processes --- including recurrent disease episodes, neuron firing, and communication patterns among humans --- can be described using inter-event time (IET) distributions. Many such processes are ongoing, although event sequences are only available during a finite observation window. Because the observation time window is more likely to begin or end during long IETs than during short ones, the analysis of such data is susceptible to a bias induced by the finite observation period. In this paper, we illustrate how this length bias is born and how it can be corrected. To do this, we model event sequences using stationary renewal processes, and we formulate simple heuristics for determining the severity of the bias. To illustrate our results, we focus on the example of empirical communication networks, which are temporal networks that are constructed from communication events. The IET distributions of such systems guide efforts to build models of human behavior, and the variance of IETs is v...
Real-Time Reactive Power Distribution in Microgrids by Dynamic Programing
DEFF Research Database (Denmark)
Levron, Yoash; Beck, Yuval; Katzir, Liran
2017-01-01
combination of reactive powers, by means of dynamic programming. Since every single step involves a one-dimensional problem, the complexity of the solution is only linear with the number of clusters, and as a result, a globally optimal solution may be obtained in real time. The paper includes the results......In this paper a new real-time optimization method for reactive power distribution in microgrids is proposed. The method enables location of a globally optimal distribution of reactive power under normal operating conditions. The method exploits the typical compact structure of microgrids to obtain...... a solution by parts, using the dynamic programming method and Bellman equation. The proposed solution method is based on the fact that the microgrid is designed with a central feeder line to which clusters of generators and loads are connected, and is suitable for microgrids with ring topologies as well...
The distribution of “time of flight” in three dimensional stationary chaotic advection
Energy Technology Data Exchange (ETDEWEB)
Raynal, Florence; Carrière, Philippe [LMFA, UMR CNRS–Université de Lyon, École Centrale de Lyon–Université Lyon 1–INSA Lyon, École Centrale de Lyon, 36 Avenue Guy de Collongue, 69134 Écully cédex (France)
2015-04-15
The distributions of “time of flight” (time spent by a single fluid particle between two crossings of the Poincaré section) are investigated for five different three dimensional stationary chaotic mixers. Above all, we study the large tails of those distributions and show that mainly two types of behaviors are encountered. In the case of slipping walls, as expected, we obtain an exponential decay, which, however, does not scale with the Lyapunov exponent. Using a simple model, we suggest that this decay is related to the negative eigenvalues of the fixed points of the flow. When no-slip walls are considered, as predicted by the model, the behavior is radically different, with a very large tail following a power law with an exponent close to −3.
Directory of Open Access Journals (Sweden)
Mário Ferreira
2015-12-01
Full Text Available Imperfect detection (i.e., failure to detect a species when the species is present is increasingly recognized as an important source of uncertainty and bias in species distribution modeling. Although methods have been developed to solve this problem by explicitly incorporating variation in detectability in the modeling procedure, their use in freshwater systems remains limited. This is probably because most methods imply repeated sampling (≥ 2 of each location within a short time frame, which may be impractical or too expensive in most studies. Here we explore a novel approach to control for detectability based on the time-to-first-detection, which requires only a single sampling occasion and so may find more general applicability in freshwaters. The approach uses a Bayesian framework to combine conventional occupancy modeling with techniques borrowed from parametric survival analysis, jointly modeling factors affecting the probability of occupancy and the time required to detect a species. To illustrate the method, we modeled large scale factors (elevation, stream order and precipitation affecting the distribution of six fish species in a catchment located in north-eastern Portugal, while accounting for factors potentially affecting detectability at sampling points (stream depth and width. Species detectability was most influenced by depth and to lesser extent by stream width and tended to increase over time for most species. Occupancy was consistently affected by stream order, elevation and annual precipitation. These species presented a widespread distribution with higher uncertainty in tributaries and upper stream reaches. This approach can be used to estimate sampling efficiency and provide a practical framework to incorporate variations in the detection rate in fish distribution models.
A Study of the Application of the Lognormal Distribution to Corrective Maintenance Repair Time
1979-06-01
PERFORMING ORGANIZATION NAM AND AOOREW I0. PROGRAM ELEMENT. PROJECT. TASK Naval Postgraduate School AREA & WORK UNIT NUMERS Monterey, California 93940 11...from the more usual procedure in which the test statistic is compared to a value which is such that the area under the distribution to its right is...Most of the sets of data show that the lognormal distribucion cannot be rejected as an adequate descriptor for corrective maintenance repair time
Time-cost analysis of a quantum key distribution system clocked at 100 MHz
Mo, Xiaofan; Chan, Philip; Healey, Chris; Hosier, Steve; Tittel, Wolfgang
2011-01-01
We describe the realization of a quantum key distribution (QKD) system clocked at 100 MHz. The system includes classical postprocessing implemented via software, and is operated over a 12 km standard telecommunication dark fiber in a real-world environment. A time-cost analysis of the sifted, error-corrected, and secret key rates relative to the raw key rate is presented, and the scalability of our implementation with respect to higher secret key rates is discussed.
FINE-GRAINED DISTRIBUTED MULTIMEDIA SYNCHRONIZA- TION MODEL--ENHANCED FUZZY-TIMING PETRI NET
Institute of Scientific and Technical Information of China (English)
韩莹洁; 孙永强; 吴哲辉
2001-01-01
A fine-grained distributed multimedia synchronization model--Enhanced Fuzzy timing Petri Net was proposed which is good at modeling indeterminacy and fuzzy. To satisfy the need of maximum tolerable jitter, the sufficient conditions are given in intra-object synchronization. Method to find a proper granularity in inter-object synchronization is also given to satisfy skew. Exceptions are detected and corrected as early as possible using restricted blocking method.
Influence of Heat Sources and Relaxation Time on Temperature Distribution in Tissues
Directory of Open Access Journals (Sweden)
Sharma S.
2014-05-01
Full Text Available In the present study, the temperature fluctuations in tissues based on Penne’s bio-heat transfer equation is investigated by applying the Laplace and Hankel transforms. To get the solution in a physical form, a numerical inversion technique has been applied. The temporal and spatial distribution of temperature is investigated with the effect of relaxation time and is presented graphically.
Institute of Scientific and Technical Information of China (English)
Chen Di-Lan; Zhang Wei-Dong
2008-01-01
This paper is concerned with the problem of robust H∞ control for structured uncertain stochastic neural networks with both discrete and distributed time varying delays. A sufficient condition is presented for the existence of H∞ control based on the Lyapunov stability theory. The stability criterion is described in terms of linear matrix inequalities (LMIs),which can be easily checked in practice. An example is provided to demonstrate the effectiveness of the proposed result.
Time-Frequency Distribution of Music based on Sparse Wavelet Packet Representations
DEFF Research Database (Denmark)
Endelt, Line Ørtoft
We introduce a new method for generating time-frequency distributions, which is particularly useful for the analysis of music signals. The method presented here is based on $\\ell1$ sparse representations of music signals in a redundant wavelet packet dictionary. The representations are found usin......, by masking the energy from less structured music instruments. We present four examples for visualizing structured content, including vocal and single instrument....
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...
Contribution of static and dynamic load balancing in a real-time distributed air defence simulation
CSIR Research Space (South Africa)
Duvenhage, B
2008-05-01
Full Text Available and Dynamic Load Balancing In A Real-Time Distributed Air Defence Simulation Mr Bernardt Duvenhage; Mr Jan J. Nel Council for Scientific and Industrial Research (CSIR) bduvenhage@csir.co.za, cnel@csir.co.za Abstract. Simulations with a large number... system. The measure to which dynamic load balancing could further enhance the performance is then explored. Such knowledge forms the basis for further load balance research. 1. INTRODUCTION The South African Council for Scientific and Industrial...
Wenbo Wu; Jiahong Liang; Xinyu Yao; Baohong Liu
2014-01-01
This paper addresses the problem of task allocation in real-time distributed systems with the goal of maximizing the system reliability, which has been shown to be NP-hard. We take account of the deadline constraint to formulate this problem and then propose an algorithm called chaotic adaptive simulated annealing (XASA) to solve the problem. Firstly, XASA begins with chaotic optimization which takes a chaotic walk in the solution space and generates several local minima; secondly XASA improv...
Toews, M. W.; Daughney, C.; Morgenstern, U.; Petrus, K.; Evison, R.; Jackson, B. M.; Cornaton, F. J.
2013-12-01
The 3000 km2 Wairarapa Valley is an important agricultural region near Wellington, New Zealand. Improved management of land and water within the region requires understanding of the spatial and temporal variations of water age. This study combines the two main methods currently available for determination of water age: numerical groundwater models and hydrological tracers. A transient finite element groundwater flow and mass transport model was calibrated to match time series measurements of groundwater level and tritium concentration. The groundwater flow model incorporates spatio-temporal recharge, variable stream flow and levels, and variable pump rates. The time-marching Laplace transform Galerkin (TMLTG) technique was then used to evaluate the full spectrum of groundwater age (i.e. age distribution) at each model node and at each time step. To our knowledge this study is the first application of the TMLTG technique to a real-world example, made possible by the rich time-series dataset of tritium measurements that exists for the Wairarapa Valley. Results showed that travel time from the land surface through the aquifer system varies from a few years to several decades and is strongly dependent on location and time. Results also demonstrated important differences between the transient age distributions derived from the TMLTG technique compared to the much simpler steady-state lumped parameter models that are frequently applied to interpret age tracer data. Finally, results had direct application to land and water management, for example for identification of land areas where age distributions vary seasonally, affecting the security of groundwater supplies used for drinking water.
On The Estimation of Survival Function and Parameter Exponential Life Time Distribution
Directory of Open Access Journals (Sweden)
Hadeel S. Al-Kutubi
2009-01-01
Full Text Available Problem statement: The study and research of survival or reliability or life time belong to the same area of study but they may belong to a different area of application. In survival analysis one can use several life time distribution, exponential distribution with mean life time θ is one of them. To estimate this parameter and survival function we must be used estimation procedures with less MSE and MPE. Approach: The only statistical theory that combined modeling inherent uncertainty and statistical uncertainty is Bayesian statistics. The theorem of Bayes provided a solution to how learn from data. Bayes theorem was depending on prior and posterior distribution and standard Bayes estimator depends on Jeffery prior information. In this study we annexed Jeffery prior information to get the modify Bayes estimator and then compared it with standard Bayes estimator and maximum likelihood estimator to find the best (less MSE and MPE. Results: when we derived Bayesian and Maximum likelihood of the scale parameter and survival functions. Simulation study was used to compare between estimators and Mean Square Error (MSE and Mean Percentage Error (MPE of estimators are computed. Conclusion: The new proposed estimator of modify Bayes estimator in parameter and survival function was the best estimator (less MSE and MPE when we compared it with standard Bayes and maximum likelihood estimator.
Developing a Near Real-time System for Earthquake Slip Distribution Inversion
Zhao, Li; Hsieh, Ming-Che; Luo, Yan; Ji, Chen
2016-04-01
Advances in observational and computational seismology in the past two decades have enabled completely automatic and real-time determinations of the focal mechanisms of earthquake point sources. However, seismic radiations from moderate and large earthquakes often exhibit strong finite-source directivity effect, which is critically important for accurate ground motion estimations and earthquake damage assessments. Therefore, an effective procedure to determine earthquake rupture processes in near real-time is in high demand for hazard mitigation and risk assessment purposes. In this study, we develop an efficient waveform inversion approach for the purpose of solving for finite-fault models in 3D structure. Full slip distribution inversions are carried out based on the identified fault planes in the point-source solutions. To ensure efficiency in calculating 3D synthetics during slip distribution inversions, a database of strain Green tensors (SGT) is established for 3D structural model with realistic surface topography. The SGT database enables rapid calculations of accurate synthetic seismograms for waveform inversion on a regular desktop or even a laptop PC. We demonstrate our source inversion approach using two moderate earthquakes (Mw~6.0) in Taiwan and in mainland China. Our results show that 3D velocity model provides better waveform fitting with more spatially concentrated slip distributions. Our source inversion technique based on the SGT database is effective for semi-automatic, near real-time determinations of finite-source solutions for seismic hazard mitigation purposes.
The practice of dwelling and the nature of decision making
DEFF Research Database (Denmark)
Fyhn, Håkon; Baron, Nina
2016-01-01
There exists a political desire to make buildings more energy efficient and resilient to extreme weather. For existing private housing this is done through refurbishment and retrofitting. In response, various projects and policies aiming to influence decisions made by homeowners in relation...... of dwelling”. We see maintenance, refurbishment and reparations as part of an ongoing practice of dwelling. In this light, decision making is just one of many aspects that contribute to shaping the actions of homeowners when they invest time and money in their properties....... to refurbishment. Focus on decisions seems to be based on a perspective where actions are understood to be the result of isolated decisions. By means of case studies from Denmark and Norway we challenge this point of view. Based on a practice theoretical approach we argue that homeowners’ actions should be seen...
Wang, Jin; Leite, Vitor; Stell, George; Lee, Chi-Lun
2002-03-01
We study the distribution of first passage times of biomolecular folding and reactions through the general framework of energy landscape theory. Both the analytical and lattice simulation results show above cirtain specific temperature, the distribution of first passage time is log-normal, while under the same temperature, the distribution starts to develop fatty tails and deviate from the log-normal distribution, indicating intermittency whereas rare events might dominate the whole process. A power law distribution of first passage time was found analytically in this situation. Applications and connections to experiments on single molecule reaction dynamics are studied.
DEFF Research Database (Denmark)
Costanzo, Giuseppe Tommaso; Bernstein, Andrey; Chamorro, Lorenzo Reyes
2015-01-01
This paper presents a systematic approach for abstracting the flexibility of a building space heating system and using it within a composable framework for real-time explicit power control of microgrids and, more in general, active distribution networks. In particular, the proposed approach...... is developed within the context of a previously defined microgrid control framework, called COMMELEC, conceived for the explicit and real-time control of these specific networks. The designed control algorithm is totally independent from the need of a building model and allows exploiting the intrinsic thermal...
Distributed acoustic mapping based on interferometry of phase optical time-domain reflectometry
Wang, Chang; Wang, Chen; Shang, Ying; Liu, Xiaohui; Peng, Gangding
2015-07-01
We demonstrate the design and characterization of a distributed optical fiber sensing system based on Michelson interferometer of the phase sensitive optical time domain reflectometer (φ-OTDR) for acoustic measurement. Phase, amplitude, frequency response and location information can be directly obtained at the same time by using the passive 3×3 coupler demodulation. In order to simulate sound profiles of seismic or hydroacoustic imaging, experiments on detection of multiple piezoelectric transducers (PZT) are carried out. The result shows that our system can well demodulate different acoustic sources with different intensities.
Interferometric distributed sensing system with phase optical time-domain reflectometry
Wang, Chen; Shang, Ying; Liu, Xiaohui; Wang, Chang; Wang, Hongzhong; Peng, Gangding
2016-11-01
We demonstrate a distributed optical fiber sensing system based on the Michelson interferometer of the phase sensitive optical time domain reflectometer (φ-OTDR) for acoustic measurement. Phase, amplitude, frequency response, and location information can be directly obtained at the same time by using the passive 3×3 coupler demodulation. We also set an experiment and successfully restore the acoustic information. Meanwhile, our system has preliminary realized acoustic-phase sensitivity around -150 dB (re rad/μPa) in the experiment.
Robust and flexible mapping for real-time distributed applications during the early design phases
DEFF Research Database (Denmark)
Gan, Junhe; Pop, Paul; Gruian, Flavius
2012-01-01
We are interested in mapping hard real-time applications on distributed heterogeneous architectures. An application is modeled as a set of tasks, and we consider a fixed-priority preemptive scheduling policy. We target the early design phases, when decisions have a high impact on the subsequent...... implementation choices. However, due to a lack of information, the early design phases are characterized by uncertainties, e.g., in the worst-case execution times (wcets), or in the functionality requirements. We model uncertainties in the wcets using the “percentile method”. The uncertainties...... of taking into account the uncertainties during the early design phases....
NeamÅ£u, Mihaela; Stoian, Dana; Navolan, Dan Bogdan
2014-12-01
In the present paper we provide a mathematical model that describe the hypothalamus-pituitary-thyroid axis in autoimmune (Hashimoto's) thyroiditis. Since there is a spatial separation between thyroid and pituitary gland in the body, time is needed for transportation of thyrotropin and thyroxine between the glands. Thus, the distributed time delays are considered as both weak and Dirac kernels. The delayed model is analyzed regarding the stability and bifurcation behavior. The last part contains some numerical simulations to illustrate the effectiveness of our results and conclusions.
Directory of Open Access Journals (Sweden)
Wu Kun-Shan
2002-01-01
Full Text Available In this paper, an EOQ inventory model is depleted not only by time varying demand but also by Weibull distribution deterioration, in which the inventory is permitted to start with shortages and end without shortages. A theory is developed to obtain the optimal solution of the problem; it is then illustrated with the aid of several numerical examples. Moreover, we also assume that the holding cost is a continuous, non-negative and non-decreasing function of time in order to extend the EOQ model. Finally, sensitivity of the optimal solution to changes in the values of different system parameters is also studied.
Distributed Approach for Solving Time-Dependent Problems in Multimodal Transport Networks
Directory of Open Access Journals (Sweden)
Carlos Galvez-Fernandez
2009-01-01
Full Text Available This paper presents an alternative approach for time-dependent multimodal transport problem. We describe a new graph structure to abstract multimodal networks, called transfer graph, which adapts to the distributed nature of real information sources of transportation networks. A decomposition of the Shortest Path Problem in transfer graph is proposed to optimize the computation time. This approach was computationally tested in several experimental multimodal networks having different size and complexity. The approach was integrated in the multimodal transport service of the European Carlink platform, where it has been validated in real scenarios. Comparision with other related works is provided.
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.
Energy Technology Data Exchange (ETDEWEB)
Peng, J H; Wu, Y J [School of Information Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Yu, H J [Department of Mechanics, Shanghai Jiao Tong University, Shanghai 200240 (China)], E-mail: jhpeng@ecust.edu.cn
2008-02-15
Synchronization and associative memory in a neural network composed of the widely discussed FitzHugh-Nagumo neurons is investigated in this paper. Based on the reality of the microscopic biological structure in the neural system, the couplings among those neurons are accompanied with randomly distributed time delays which models the times needed for pulses propagating on the axons from the presynaptic neurons to the postsynaptic neurons. The memory is represented in the spatiotemporal firing pattern of the neurons, and the memory retrieval is accomplished with the fluctuations of the noise in the system.
Modeling and Analysis of Scheduling for Distributed Real-time Embedded Systems
Institute of Scientific and Technical Information of China (English)
Hai-Tao Zhang; Gui-Fang Wu
2010-01-01
Aimed at the deficiencies of resources based time Petri nets(RBTPN)in doing scheduling analysis for distributed real-time embedded systems,the assemblage condition of complex scheduling sequences is presented to easily compute scheduling length and simplify scheduling analysis.Based on this,a new hierarchical RBTPN model is proposed.The model introduces the definition of transition border set,and represents it as an abstract transition.The abstract transition possesses all resources of the set,and has the highest priority of each resource;the execution time of abstract transition is the longest time of all possible scheduling sequences.According to the characteristics and assemblage condition of RBTPN,the refinement conditions of transition border set are given,and the conditions ensure the correction of scheduling analysis.As a result,it is easy for us to understand the scheduling model and perform scheduling analysis.
Time-resolved angular distributions of plume ions from silver at low and medium laser fluence
DEFF Research Database (Denmark)
Christensen, Bo Toftmann; Schou, Jørgen
in a vacuum chamber (~ 10-7 mbar) with a Nd:YAG laser at a wavelength of 355 nm and made detailed measurements of the time-resolved angular distribution. The ion flow in different directions has been measured with a hemispherical array of Langmuir probes, by which the time-of-flight spectra, as well...... 70 eV up to 145 eV in a direction normal to the target surface with increasing fluence. With increasing observation angle the time-of-flight spectra exhibit a peak at longer flight times, i.e. at a lower kinetic energy. At the highest fluence the ionized fraction of the ablated particles exceeds 0.5....
Power Aware Scheduling for Resource Constrained Distributed Real-Time Systems
Directory of Open Access Journals (Sweden)
Santhi Baskaran
2010-08-01
Full Text Available Power management has become popular in mobile computing as well as in server farms. Although a lot of work has been done to manage the energy consumption on uniprocessor real-time systems, there is less work done on their multicomputer counterparts. For a set of real-time tasks with precedence and resource constraints executing on a distributed system, we propose a dynamic slack management technique for feedback control scheduling (FCS algorithm known as modifiedFCS algorithm. This algorithm schedules dependant periodic real-time task sets by effectively managing exclusive access resources with strict timing constraints along with energy efficiency. Simulation results show that, in comparison to commonly used greedy technique, the proposed technique achieves 28 percent less power consumption when validated with random task graphs.
Ma, Shu-Ying; Yan, Wei-Nan; Xu, Liang
2015-11-01
A quantitative retrieval of 3-D distribution of energetic ions as energetic neutral atoms (ENA) sources is a challenging task. In this paper the voxel computerized tomography (CT) method is initially applied to reconstruct the 3-D distribution of energetic ions in the magnetospheric ring current (RC) region from ENA emission images on board multiple spacecraft. To weaken the influence of low-altitude emission (LAE) on the reconstruction, the LAE-associated ENA intensities are corrected by invoking the thick-target approximation. To overcome the divergence in iteration due to discordant instrument biases, a differential ENA voxel CT method is developed. The method is proved reliable and advantageous by numerical simulation for the case of constant bias independent of viewing angle. Then this method is implemented with ENA data measured by the Two Wide-angle Imaging Neutral-atom Spectrometers mission which performs stereoscopic ENA imaging. The 3-D spatial distributions and energy spectra of RC ion flux intensity are reconstructed for energies of 4-50 keV during the main phase of a major magnetic storm. The retrieved ion flux distributions seem to correspond to an asymmetric partial RC, located mainly around midnight favoring the postmidnight with L = 3.5-7.0 in the equatorial plane. The RC ion distributions with magnetic local time depend on energy, with major equatorial flux peak for lower energy located east of that for higher energy. In comparison with the ion energy spectra measured by Time History of Events and Macroscale Interactions during Substorms-D satellite flying in the RC region, the retrieved spectrum from remotely sensed ENA images are well matched with the in situ measurements.
Serial Spike Time Correlations Affect Probability Distribution of Joint Spike Events.
Shahi, Mina; van Vreeswijk, Carl; Pipa, Gordon
2016-01-01
Detecting the existence of temporally coordinated spiking activity, and its role in information processing in the cortex, has remained a major challenge for neuroscience research. Different methods and approaches have been suggested to test whether the observed synchronized events are significantly different from those expected by chance. To analyze the simultaneous spike trains for precise spike correlation, these methods typically model the spike trains as a Poisson process implying that the generation of each spike is independent of all the other spikes. However, studies have shown that neural spike trains exhibit dependence among spike sequences, such as the absolute and relative refractory periods which govern the spike probability of the oncoming action potential based on the time of the last spike, or the bursting behavior, which is characterized by short epochs of rapid action potentials, followed by longer episodes of silence. Here we investigate non-renewal processes with the inter-spike interval distribution model that incorporates spike-history dependence of individual neurons. For that, we use the Monte Carlo method to estimate the full shape of the coincidence count distribution and to generate false positives for coincidence detection. The results show that compared to the distributions based on homogeneous Poisson processes, and also non-Poisson processes, the width of the distribution of joint spike events changes. Non-renewal processes can lead to both heavy tailed or narrow coincidence distribution. We conclude that small differences in the exact autostructure of the point process can cause large differences in the width of a coincidence distribution. Therefore, manipulations of the autostructure for the estimation of significance of joint spike events seem to be inadequate.
Directory of Open Access Journals (Sweden)
D. Sudharsan
2012-03-01
Full Text Available Wireless Sensor Network (WSN is well known for distributed real time systems for various applications. In order to handle the increasing functionality and complexity of high resolution spatio-temporal sensorydatabase, there is a strong need for a system/tool to analyse real time data associated with distributed sensor network systems. There are a few package/systems available to maintain the near real time database system/management, which are expensive and requires expertise. Hence, there is a need for a cost effective and easy to use dynamic real-time data repository system to provide real time data (raw as well as usable units in a structured format. In the present study, a distributed sensor network system, with Agrisens (AS and FieldServer (FS as well as FS-based Flux Tower and FieldTwitter, is used, which consists of network of sensors and field images to observe/collect the real time weather, crop and environmental parameters for precision agriculture. The real time FieldServer-based spatio-temporal high resolution dynamic sensory data was converted into Dynamic Real-Time Database Management System (DRTDBMS in a structured format for both raw and converted (with usable units data. A web interface has been developed to access the DRTDBMS and exclusive domain has been created with the help of open/free Information and Communication Technology (ICT tools in Extendable Markup Language (XML using (Hypertext preprocessor PHP algorithms and with eXtensible Hyper Text Markup Language (XHTML self-scripting. The proposed DRTDBMS prototype, called GeoSense DRTDBMS, which is a part of the ongoing IndoJapan initiative ‘ICT and Sensor Network based Decision Support Systems in Agriculture and EnvironmentAssessment’, will be integrated with GeoSense cloud server to provide database (dynamic real-time weather/soil/crop and environmental parameters and modeling services (crop water requirement and simulated rice yield modeling. GeoSense-cloud server
The meaning of dwelling features: conceptual and methodological issues
Coolen, H.C.C.H.
2008-01-01
This study is about the meaning of dwelling features. It relates the research areas of housing preferences and the meaning of a dwelling with each other and with aspects of the means-end approach as applied in marketing research. It results in a conceptual and methodological framework for studying t
Investigation of the delay time distribution of high power microwave surface flashover
Foster, J.; Krompholz, H.; Neuber, A.
2011-01-01
Characterizing and modeling the statistics associated with the initiation of gas breakdown has proven to be difficult due to a variety of rather unexplored phenomena involved. Experimental conditions for high power microwave window breakdown for pressures on the order of 100 to several 100 torr are complex: there are little to no naturally occurring free electrons in the breakdown region. The initial electron generation rate, from an external source, for example, is time dependent and so is the charge carrier amplification in the increasing radio frequency (RF) field amplitude with a rise time of 50 ns, which can be on the same order as the breakdown delay time. The probability of reaching a critical electron density within a given time period is composed of the statistical waiting time for the appearance of initiating electrons in the high-field region and the build-up of an avalanche with an inherent statistical distribution of the electron number. High power microwave breakdown and its delay time is of critical importance, since it limits the transmission through necessary windows, especially for high power, high altitude, low pressure applications. The delay time distribution of pulsed high power microwave surface flashover has been examined for nitrogen and argon as test gases for pressures ranging from 60 to 400 torr, with and without external UV illumination. A model has been developed for predicting the discharge delay time for these conditions. The results provide indications that field induced electron generation, other than standard field emission, plays a dominant role, which might be valid for other gas discharge types as well.
Origins and Application of Postmodern Trends in Private Dwelling-Houses of Lithuania, 1987–1998
Directory of Open Access Journals (Sweden)
Aistė Galaunytė
2013-10-01
Full Text Available On 28 September 1987, the resolution No. 264 On Further Development of Individual Housing in the Republic passed by the Central Committee of the Council of Ministers of the Lithuanian SSR restored the typological group of private dwelling-houses to Lithuanian towns after a break of nearly three decades. Post-modern trends in architecture that prevailed in western countries at that time reached Lithuania in the form of limited spectrum of architectural press. Architectural expression of individual dwelling-houses in Lithuania relied specifically on projects published in foreign magazines (mostly, of Japan, the U.S.A and Western Europe, and later – in the local periodicals. Different features of such analogous architecture were adapted in Lithuanian dwelling-houses in different ways: the spatial structure of the building was used and interpreted in ones, while in the others – only certain specific details, most often published in such professional press. Three groups of individual dwelling-houses were formed: the elite – benchmark-type, typical -adapted and self-taught architecture. They represented examples of architecture, which over the ten-year’s period were built in parallel and intense mode, until finally the economic conditions prevalent in the post-Soviet Lithuania led to the more practical approach to one’s housing, and the style of post-modernism became unfashionable in Lithuania just like in the remaining part of the world.
Indoor air quality in energy-efficient dwellings: levels and sources of pollutants.
Derbez, Mickaël; Wyart, Guillaume; Le Ponner, Eline; Ramalho, Olivier; Ribéron, Jacques; Mandin, Corinne
2017-09-28
Worldwide, public policies are promoting energy-efficient buildings and accelerating the thermal renovation of existing buildings. The effects of these changes on the indoor air quality (IAQ) in these buildings remain insufficiently understood. In this context, a field study was conducted in 72 energy-efficient dwellings to describe the pollutants known to be associated with health concerns. Measured parameters included the concentrations of 19 volatile organic compounds and aldehydes, nitrogen dioxide, particulate matter (PM2.5 ), radon, temperature and relative humidity. The air stuffiness index and night-time air exchange rate were calculated from the monitored carbon dioxide (CO2 ) concentrations. Indoor and outdoor measurements were performed at each dwelling during one week in each of the two following seasons: heating and non-heating. Moreover, questionnaires were completed by the occupants to characterize the building, equipment, household and occupants' habits. Perspective on our results was provided by previous measurements made in low-energy European dwellings. Statistical comparisons with the French housing stock and a pilot study showed higher concentrations of terpenes, i.e., alpha-pinene and limonene, and hexaldehyde in our study than in previous studies. Alpha-pinene and hexaldehyde are emitted by wood or wood-based products used for the construction, insulation, decoration and furnishings of the dwellings, whereas limonene is more associated with discontinuous sources related to human activities. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
The joint choice of tenure, dwelling type and size
DEFF Research Database (Denmark)
Frenkel, Amnon; Bendit, Eduard; Kaplan, Sigal
Real-estate market trends regarding housing preferences for tenure, dwelling type and size carry long term implications for cities’ spatial development and compactness. Much attention have been given to the impact of household demographics and socio-economic characteristics on joint housing choices...... that active versus home-oriented lifestyle plays an important role in housing preferences of tenure, dwelling type and size, while controlling for household socio-economic characteristics. The choice model employed for tenure and dwelling type coupled with dwelling unit size is the multinomial logit ordered...... regarding housing preferences, socio-economic characteristics, and activity patterns. The empirical findings show that the tendency of knowledge-workers to reside in owned large dwelling units, preferably single detached houses, increases with high engagement in home-oriented activities, while the tendency...