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The article describes mathematical models of traffic flows to initiate different traffic flow processes. Separate elements of traffic flow models are made in a way to be connected together to get a single complex model. A model of straight road with different boundary conditions is presented as a separate part of the network traffic flow model. First testing is conducted in case the final point of the whole modelled traffic line is closed and no output from that point is possible. The second test is performed when a constant value of traffic flow speed and traffic flow rate is entered. Mathematical simulation is carried out and the obtained results are listed.
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Takači, Arpad. "Mathematical and simulation models of traffic flow." PAMM 5, no. 1 (December 2005): 633–34. http://dx.doi.org/10.1002/pamm.200510293.
Junevičius, Raimundas, Marijonas Bogdevičius, and Ádám Török. "MODELLING OF INTERNAL COMBUSTION ENGINES’ EMISSION THROUGH THE USE OF TRAFFIC FLOW MATHEMATICAL MODELS." TRANSPORT 26, no. 3 (October 5, 2011): 271–78. http://dx.doi.org/10.3846/16484142.2011.621978.
Road traffic flows on a straight road segment are modelled in this article. The mathematical model of traffic flows has been constructed by using the method of lumped parameters. CO2, CO, CH, NOx, PM regression equations of internal combustion engines’ (ICE) emission has been developed. The accuracy of regression equations is 0.98÷0.99. The article presents assumptions for constructing the mathematical model, description of the mathematical model and gives simulation results. Traffic flow parameters, such as traffic flow concentration and traffic flow speed are presented as modelling results. ICE emission depending on the concentration and traffic flow speed are presented as well.
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Otegen, Diana Assankhankyzy. "MODELS OF TRAFFIC FLOW DYNAMICS ON HIGHWAYS." Вестник КазАТК 116, no. 1 (March 15, 2021): 236–41. http://dx.doi.org/10.52167/1609-1817-2021-116-1-236-241.
The paper is an analytical review of the currently existing methods of traffic flows modeling. The movement of vehicles on the road can be modeled in different ways. Mathematical models as tools that allow us to study complex processes in the real world, including transport infrastructure, without capital expenditures, are a popular tool for solving many problems in various spheres of the national economy. There are several approaches to mathematical modeling of traffic flows. In microscopic models, the law of motion of each car is set, depending on its current position, speed, characteristics of the movement of neighboring cars, and other factors. Microscopic models, in turn, can be divided into models that are continuous in space and time, and into models that are discrete in space and time, the so-called cellular automata. In macroscopic models, the transport flow is considered as a fluid flow with special properties. The equations of the macroscopic model establish the relationship between the flow, density, speed of movement, possibly acceleration, and so on. Macroscopic models can also be continuous or discrete. In continuous models, the change in the state of a road section without branches and intersections is usually described by partial differential equations. Modeling traffic flows is necessary because active experiments in the existing transport network are fraught with unpredictable consequences, and in many cases are not feasible at all. The work presents a description and analysis of the models, and of their advantages and disadvantages.
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Guseynov, Sharif E., and Alexander V. Berezhnoy. "MODELLING OF URBAN TRAFFIC FLOW." Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference 1 (June 15, 2017): 109. http://dx.doi.org/10.17770/etr2017vol1.2632.
In this paper non-deterministic motion of urban traffic is studied under certain assumptions. Based on those assumptions discrete and continuous mathematical models are developed: continuous model is written as the Cauchy initial-value problem for the integro-differential equation, whence among other things it is obtained the Fokker-Planck equation. Besides, the sufficient condition ensuring the mathematical legitimacy of the developed continuous model is formulated.
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Tyagi, V., S. Darbha, and K. R. Rajagopal. "A review of the mathematical models for traffic flow." International Journal of Advances in Engineering Sciences and Applied Mathematics 1, no. 1 (July 2009): 53–68. http://dx.doi.org/10.1007/s12572-009-0005-8.
POSPELOV, PAVEL I., ALEXANDER G. TATASHEV, ALEXEY V. TERENTYEV, MARIA Yu KARELINA, and MARINA V. YASHINA. "BARTLETT FLOWS AND MATHEMATICAL DESCRIPTION OF MOTOR TRAFFIC FLOWS." H&ES Research 13, no. 6 (2021): 34–41. http://dx.doi.org/10.36724/2409-5419-2021-13-6-34-41.
Introduction: The class of mathematical traffic models is based on the theory of queuing. In these models, the application entering the service system corresponds to the vehicle. When developing a traffic model formulated in terms of queuing, it is necessary to specify a random flow that is incoming to the queuing system. The purpose of the study: Traditional queuing systems with recurrent incoming flow under appropriate conditions do not reflect the specific features of real traffic flows. Under certain conditions, for example, it may be appropriate to use a Markov-type flow in the model, the intensity of which depends on the state of a mathematical object called the control device. In the general case, such a flow can be specified as non-uniform, and with such a task, each request is assigned a type that also depends on the state of the control device. Setting the qualitative structure and parameters of a random flow depends on the assessment of the speed characteristics of the vehicles that form the flow, and, therefore, is related to the issues of studying the speed characteristics of real vehicles. Practical significance: At a sufficiently low density of the traffic flow, the incoming flow is close to the Poisson one. As traffic increases and road conditions worsen, the risk of overtaking increases and clusters are formed, consisting of a slow car moving in front and a group of fast cars that cannot overtake a slow one. In such cases, we can assume that the incoming flow is a Bartlett flow, which has the following form: clusters form a Poisson flow, and the cluster length distribution is a two-parameter Bartlett distribution. One of the parameters of this distribution is the probability of having a group of fast cars, and the second parameter characterizes the distribution of the number of cars in this group. Discussion: In this paper, we study the questions of setting a qualitative probabilistic structure and quantitative parameters of random flows, which are elements of queuing systems used as traffic models.
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Bazaras, Jonas, Janina Jablonskytė, and Eglė Jotautienė. "INTERDEPENDENCE OF NOISE AND TRAFFIC FLOW." TRANSPORT 23, no. 1 (March 31, 2008): 67–72. http://dx.doi.org/10.3846/1648-4142.2008.23.67-72.
Traffic flows in cities, especially in city centres, are intensive and uneven, moreover, registered noise levels exceed allowable limits. Noise levels have been measured at K. Mindaugo ave. and Birštono street crossing in Kaunas and data of automated traffic flow registration equipment have been used. A constant reduction of noise level from the beginning till the end of the green light has been identified ‐ “hot starts” generated noise dominates. To make estimates of noise and traffic flow interdependency, mathematical statistical models have been applied. Parameter distribution patterns have been analysed, prediction models have been composed.
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Oleg Fyodorovich Danilov, Victor Ivanovich Kolesov, Denis Alexandrovich Sorokin, and Maxim Leonidovich Gulaev. "Study on the Vehicle Linear Dynamic Interval in a Traffic Flow." Communications - Scientific letters of the University of Zilina 23, no. 1 (January 4, 2021): E11—E22. http://dx.doi.org/10.26552/com.c.2021.1.e11-e22.
The transportation industry of a modern city involves the effective systems for the road traffic management. To manage any object is impossible without understanding its specifics. The tasks of road traffic management are based on mathematical models of traffic flows. The “following the leader” model based on the linear dynamic interval of vehicles has become widely accepted in the model analysis. The paper discusses the mathematical model of the linear dynamic interval of vehicles; the model is identified structurally and parametrically. Coefficients of the model are analyzed in detail; a generalized assessment of the dynamic performance of the traffic flow, evolved in various road conditions, is given. The study has resulted in the proposed basic models for traffic flows that can be used for algorithmic support of the model analysis of traffic flows and the road traffic management.
Дисертації з теми "Traffic flow Mathematical models":
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Yan, Li, and 顏理. "On the traffic flow control system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39431174.
Yue, Yang, and 樂陽. "Spatial-temporal dependency of traffic flow and its implications for short-term traffic forecasting." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B35507366.
Lierkamp, Darren. "Simulating the effects of following distance on a high-flow freeway." Full text available online (restricted access), 2003. http://images.lib.monash.edu.au/ts/theses/Lierkamp.pdf.
"CP830 Research Project and Thesis 2". Includes bibliographical references (p. 80-93) Electronic reproduction.[S.l. :s.n.],2003.Electronic data.Mode of access: World Wide Web.System requirements: Adobe Acrobat reader software for PDF files.Access restricted to institutions with a subscription.
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Wong, Chun-kuen, and 黃春權. "Dynamic macroscopic modeling of highway traffic flows." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31243757.
Peng, Jixian, and 彭继娴. "Macroscopic characteristics of dense road networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/195994.
In the continuum modeling of traffic networks, a macroscopic cost-flow function (MCF) and macroscopic fundamental diagram (MFD) can be used to represent the fundamental relationships between traffic quantities such as speed, flow, and density. The MCF governs the steady-state cost-flow relationship, whereas the MFD represents the instantaneous inter-relationship between speed, flow, and density of traffic streams. This thesis explores the influence of network topologies on the MCF and MFD.
The Hong Kong road system is divided into unit-sized road networks with various physical characteristics for which the network structure and signal timings are reserved. By universally scaling the origin-destination (OD) matrices of the morning peak, traffic conditions ranging from free-flow to congestion are created for microscopic simulation. From the simulation results, an MCF that relates the average journey time and the number of vehicles traveling through the network in one hour and an MFD that relates space to the mean speed and average density aggregated across 300s intervals are derived. The MCF and MFD are calibrated with mathematical models for each network.
The density of roads, junctions, and signal junctions all influence the value of the macroscopic parameters in the MCF and MFD, and predictive equations are constructed that relate the macroscopic parameters to the network topological characteristics. Based on the fitting performance of the mathematical models, recommendations are made for selecting MCF and MFD models for continuum modeling. published_or_final_version Civil Engineering Master Master of Philosophy
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溫建勇 and Kin-yung Wan. "Biham-middleton-levine traffic model in different spatial dimensions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B3122183X.
Wong, Chung-yin Philip, and 黃仲賢. "The development of pedestrian flow model." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B48194025.
This dissertation reported on the findings of the characteristics of the pedestrian
flows in Chinese New Year Eve Fair in Hong Kong and, the recommendations to its
crowd control measures. Since most of the pedestrian flow models were developed
for general purposes under normal condition, special models developed specifically
for major events such as bazaars, fairs and festivals in Hong Kong were required to
understand their pedestrian flow patterns. In this dissertation, pedestrian flows in the
Fair were videotaped and data was extracted for calibrating several pedestrian flow
models. These included the conventional models developed by Greenshields,
Greenberg, Pipes-Munjal, Underwood, Drake, Wong et al. and four modifications of
these models for simulating isotropic and bi-directional pedestrian flow scenarios.
The free flow speed of the pedestrians in the Chinese New Year Eve Fair was found
to be around 0.69-0.84 m/s, slower than those identified in other researches. Besides,
the results of these models showed the relationships between walking speed, density
and flow of the pedestrians in the Fair. Also, the effects of bi-directional flow to
pedestrian flows were assessed and quantified. These findings obtained from models
were then used as a basis for formulating crowd control strategy of major events in
Hong Kong. published_or_final_version Transport Policy and Planning Master Master of Arts in Transport Policy and Planning
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Kim, Changkyun. "Development and evaluation of traffic prediction systems." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-164007/.
Sivanandan, R. "A linear programming approach for synthesizing origin-destination (O-D) trip tables from link traffic volumes." Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07102007-142518/.
Lau, Chi-yung, and 劉智勇. "Numerical studies on a few cellular automation traffic models." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31227521.
As, S. C. van. Traffic flow theory. 3rd ed. [Pretoria]: SARB Chair in Transportation Engineering, Dept. of Civil Engineering, University of Pretoria, 1990.
Puppo, Gabriella, and Andrea Tosin, eds. Mathematical Descriptions of Traffic Flow: Micro, Macro and Kinetic Models. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66560-9.
Haberman, Richard. Mathematical models: Mechanical vibrations, population dynamics, and traffic flow : an introduction to applied mathematics. Philadelphia: Society for Industrial and Applied Mathematics, 1998.
Hummer, Joseph E. Operational capacity of three-lane cross-sections. Raleigh, NC: Center for Transportation Engineering Studies, Dept. of Civil Engineering, North Carolina State University, 2000.
Yong, Zhou. Schätzung der Verkehrsbeziehungen bei unvollständiger Information und deren Anwendung bei der Verkehrssteuerung. München: Technische Universität München, 2001.
Частини книг з теми "Traffic flow Mathematical models":
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Elefteriadou, Lily. "Mathematical and Empirical Models." In An Introduction to Traffic Flow Theory, 129–35. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-8435-6_6.
Herty, Michael, Gabriella Puppo, and Giuseppe Visconti. "From Kinetic to Macroscopic Models and Back." In Mathematical Descriptions of Traffic Flow: Micro, Macro and Kinetic Models, 17–34. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-66560-9_2.
Herty, Michael, Andrea Tosin, Giuseppe Visconti, and Mattia Zanella. "Reconstruction of Traffic Speed Distributions from Kinetic Models with Uncertainties." In Mathematical Descriptions of Traffic Flow: Micro, Macro and Kinetic Models, 1–16. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-66560-9_1.
Ramadan, Rabie, Rodolfo Ruben Rosales, and Benjamin Seibold. "Structural Properties of the Stability of Jamitons." In Mathematical Descriptions of Traffic Flow: Micro, Macro and Kinetic Models, 35–62. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-66560-9_3.
Balzotti, Caterina, and Elisa Iacomini. "Stop-and-Go Waves: A Microscopic and a Macroscopic Description." In Mathematical Descriptions of Traffic Flow: Micro, Macro and Kinetic Models, 63–78. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-66560-9_4.
Holden, Helge, and Nils Henrik Risebro. "A Mathematical Model of Traffic Flow on a Network of Roads." In Nonlinear Hyperbolic Problems: Theoretical, Applied, and Computational Aspects, 329–35. Wiesbaden: Vieweg+Teubner Verlag, 1993. http://dx.doi.org/10.1007/978-3-322-87871-7_39.
Helbing, Dirk, and Anders Johansson. "On the Controversy Around Daganzo’s Requiem for and Aw–Rascle’s Resurrection of Second-Order Traffic Flow Models." In Lecture Notes in Mathematics, 271–302. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-32160-3_4.
Тези доповідей конференцій з теми "Traffic flow Mathematical models":
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Oshkhunov, Muaed M., Martin M. Yakhutlov, Muslimat L. Sanshokova, and Liana Kh Nazarova. "Mathematical models of traffic flow of diffusion type at stochastic conditions." In 2017 International Conference "Quality Management,Transport and Information Security, Information Technologies" (IT&QM&IS). IEEE, 2017. http://dx.doi.org/10.1109/itmqis.2017.8085771.
Racila, Laurentiu. "Saturation flow mathematical model based on multiple combinations of lane groups." In CIT2016. Congreso de Ingeniería del Transporte. Valencia: Universitat Politècnica València, 2016. http://dx.doi.org/10.4995/cit2016.2016.4254.
The ideal value of the traffic stream that can pass through an intersection is known as the saturation flow rate per hour on vehicle green time. The saturation flow is important in the understanding of the traffic light cycle and from there the understanding the Level of Service. The paper wishes to evaluate through a series of applied mathematical methods the effect of different lane grouping and critical lane group concept on the saturation flow rate. The importance of this method is that it creates a base for a signalized intersections timing plan.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4254
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Liu, Lin. "Mathematical Model of the Vehicles Percentage in Self-Driving, Cooperating Systems and Traffic Flow." In 2018 IEEE Region Ten Symposium (Tensymp). IEEE, 2018. http://dx.doi.org/10.1109/tenconspring.2018.8692000.
Nikolos, I. K., A. I. Delis, and M. Papageorgiou. "Relaxation approximations to second-order traffic flow models by high-resolution schemes." In PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON NUMERICAL ANALYSIS AND APPLIED MATHEMATICS 2014 (ICNAAM-2014). AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4912741.
Albi, Giacomo, Michael Herty, and Lorenzo Pareschi. "Relaxation approximation of optimal control problems and applications to traffic flow models." In PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON FRONTIERS IN INDUSTRIAL AND APPLIED MATHEMATICS (FIAM-2018). Author(s), 2018. http://dx.doi.org/10.1063/1.5042169.
Holkin, Anton, and Aleksandr Pavlov. "SIMULATION AND MATHEMATICAL MODELING OF AUTOMOBILE TRAFFIC BY MEANS OF ANYLOGIC AND STATISTICA." In CAD/EDA/SIMULATION IN MODERN ELECTRONICS 2021. Bryansk State Technical University, 2021. http://dx.doi.org/10.30987/conferencearticle_61c997ef3f4c51.56750950.
This article describes a simulation model of a road section in the city of Kazan, created using the AnyLogic simulation modeling system. The process of creating a simulation model, optimization by AnyLogic SIM tools is described, a mathematical model of the flow of cars is constructed based on the results of a simulation experiment using the STATISTICA 10 software package.
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Vacek, Lukáš, and Václav Kučera. "Construction of fluxes at junctions for the numerical solution of traffic flow models on networks." In Programs and Algorithms of Numerical Mathematics 20. Institute of Mathematics, Czech Academy of Sciences, 2021. http://dx.doi.org/10.21136/panm.2020.15.
Nishida, Yuki, Sennosuke Watanabe, Akiko Fukuda, and Yoshihide Watanabe. "Traffic flow models with two kinds of vehicles in terms of the vector-valued cellular automata and their fuzzification." In 7TH INTERNATIONAL CONFERENCE ON MATHEMATICS: PURE, APPLIED AND COMPUTATION: Mathematics of Quantum Computing. AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0114966.
Radochinskaia, A. Zh, A. A. Yanchenko, and T. E. Malikova. "SIMULATION OF THE IMPORT BOUND CARGO TRAFFIC PROCESSING AT A CONTAINER TERMINAL IN MATLAB ENVIRONMENT." In Aerospace instrumentation and operational technologies. Saint Petersburg State University of Aerospace Instrumentation, 2021. http://dx.doi.org/10.31799/978-5-8088-1554-4-2021-2-144-149.
Issues related to the use of mathematical modeling in the process of making management decisions at a sea container terminal have been looked at. A brief overview of generally accepted approaches to the choice of a mathematical apparatus for describing the subtasks of the technological process of terminal cargo handling has been given. The stages of developing a mathematical model based on the author’s methodology for analyzing technological processes for processing import bound cargo traffic at a functioning container terminal have been described in detail. As an example, the process of developing a discrete-event simulation model for processing an import bound container flow arriving at a sea terminal in the MATLAB environment has been considered.
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Al Nageim, Hassan. "Non Destructive Testing of Low Profile Light Weight Track System." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24727.
The paper presents the results of the responses of a concrete trough of a new lightweight rail track system (LR55) to full scale non destructive tasting. The system which is made from three main components; low profile steel rail, elastomeric pad and prestressed concrete trough is developed for light rail transits in cities streets, which can significantly help in improving the traffic flow, reducing the traffic congestion and thus providing opportunities for minimising serious environmental problems such as level of noise, vibration and air pollutions and in this regards it can be considered as environmentally friendly means of transport. A mathematical model was developed where the LR55 track system was treated as multilayer beams on elastic foundations, and the model was then validate experimentally through a series of non-destructive tests on full scale model subjected to a full scale service load specified by the current BS codes of practises.
Звіти організацій з теми "Traffic flow Mathematical models":
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Siebke, Christian, Maximilian Bäumler, Madlen Ringhand, Marcus Mai, Felix Elrod, and Günther Prokop. Report on integration of the stochastic traffic simulation. Technische Universität Dresden, 2021. http://dx.doi.org/10.26128/2021.246.
As part of the AutoDrive project, the OpenPASS framework is used to develop a cognitive-stochastic traffic flow simulation for urban intersection scenarios described in deliverable D1.14. This framework was adapted and further developed. The deliverable D5.13 deals with the construction of the stochastic traffic simulation. At this point of the process, the theoretical design aspects of D4.20 are implemented. D5.13 explains the operating principles of the different modules. This includes the foundations, boundary conditions, and mathematical theory of the traffic simulation.
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Arhin, Stephen, Babin Manandhar, Kevin Obike, and Melissa Anderson. Impact of Dedicated Bus Lanes on Intersection Operations and Travel Time Model Development. Mineta Transportation Institute, June 2022. http://dx.doi.org/10.31979/mti.2022.2040.
Over the years, public transit agencies have been trying to improve their operations by continuously evaluating best practices to better serve patrons. Washington Metropolitan Area Transit Authority (WMATA) oversees the transit bus operations in the Washington Metropolitan Area (District of Columbia, some parts of Maryland and Virginia). One practice attempted by WMATA to improve bus travel time and transit reliability has been the implementation of designated bus lanes (DBLs). The District Department of Transportation (DDOT) implemented a bus priority program on selected corridors in the District of Columbia leading to the installation of red-painted DBLs on corridors of H Street, NW, and I Street, NW. This study evaluates the impacts on the performance of transit buses along with the general traffic performance at intersections on corridors with DBLs installed in Washington, DC by using a “before” and “after” approach. The team utilized non-intrusive video data to perform vehicular turning movement counts to assess the traffic flow and delays (measures of effectiveness) with a traffic simulation software. Furthermore, the team analyzed the Automatic Vehicle Locator (AVL) data provided by WMATA for buses operating on the study segments to evaluate bus travel time. The statistical analysis showed that the vehicles traveling on H Street and I Street (NW) experienced significantly lower delays during both AM (7:00–9:30 AM) and PM (4:00–6:30 PM) peak hours after the installation of bus lanes. The approximation error metrics (normalized squared errors) for the testing dataset was 0.97, indicating that the model was predicting bus travel times based on unknown data with great accuracy. WMATA can apply this research to other segments with busy bus schedules and multiple routes to evaluate the need for DBLs. Neural network models can also be used to approximate bus travel times on segments by simulating scenarios with DBLs to obtain accurate bus travel times. Such implementation could not only improve WMATA’s bus service and reliability but also alleviate general traffic delays.
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Lohne, Arild, Arne Stavland, Siv Marie Åsen, Olav Aursjø, and Aksel Hiorth. Recommended polymer workflow: Interpretation and parameter identification. University of Stavanger, November 2021. http://dx.doi.org/10.31265/usps.202.
Injecting a polymer solution into a porous medium significantly increases the modeling complexity, compared to model a polymer bulk solution. Even if the polymer solution is injected at a constant rate into the porous medium, the polymers experience different flow regimes in each pore and pore throat. The main challenge is to assign a macroscopic porous media “viscosity” to the fluid which can be used in Darcy law to get the correct relationship between the injection rate and pressure drop. One can achieve this by simply tabulating experimental results (e.g., injection rate vs pressure drop). The challenge with the tabulated approach is that it requires a huge experimental database to tabulate all kind of possible situations that might occur in a reservoir (e.g., changing temperature, salinity, flooding history, permeability, porosity, wettability etc.). The approach presented in this report is to model the mechanisms and describe them in terms of mathematical models. The mathematical model contains a limited number of parameters that needs to be determined experimentally. Once these parameters are determined, there is in principle no need to perform additional experiments.
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Tanny, Josef, Gabriel Katul, Shabtai Cohen, and Meir Teitel. Micrometeorological methods for inferring whole canopy evapotranspiration in large agricultural structures: measurements and modeling. United States Department of Agriculture, October 2015. http://dx.doi.org/10.32747/2015.7594402.bard.
Original objectives and revisions The original objectives as stated in the approved proposal were: (1) To establish guidelines for the use of micrometeorological techniques as accurate, reliable and low-cost tools for continuous monitoring of whole canopy ET of common crops grown in large agricultural structures. (2) To adapt existing methods for protected cultivation environments. (3) To combine previously derived theoretical models of air flow and scalar fluxes in large agricultural structures (an outcome of our previous BARD project) with ET data derived from application of turbulent transport techniques for different crops and structure types. All the objectives have been successfully addressed. The study was focused on both screenhouses and naturally ventilated greenhouses, and all proposed methods were examined. Background to the topic Our previous BARD project established that the eddy covariance (EC) technique is suitable for whole canopy evapotranspiration measurements in large agricultural screenhouses. Nevertheless, the eddy covariance technique remains difficult to apply in the farm due to costs, operational complexity, and post-processing of data – thereby inviting alternative techniques to be developed. The subject of this project was: 1) the evaluation of four turbulent transport (TT) techniques, namely, Surface Renewal (SR), Flux-Variance (FV), Half-order Time Derivative (HTD) and Bowen Ratio (BR), whose instrumentation needs and operational demands are not as elaborate as the EC, to estimate evapotranspiration within large agricultural structures; and 2) the development of mathematical models able to predict water savings and account for the external environmental conditions, physiological properties of the plant, and structure properties as well as to evaluate the necessary micrometeorological conditions for utilizing the above turbulent transfer methods in such protected environments. Major conclusions and achievements The major conclusions are: (i) the SR and FV techniques were suitable for reliable estimates of ET in shading and insect-proof screenhouses; (ii) The BR technique was reliable in shading screenhouses; (iii) HTD provided reasonable results in the shading and insect proof screenhouses; (iv) Quality control analysis of the EC method showed that conditions in the shading and insect proof screenhouses were reasonable for flux measurements. However, in the plastic covered greenhouse energy balance closure was poor. Therefore, the alternative methods could not be analyzed in the greenhouse; (v) A multi-layered flux footprint model was developed for a ‘generic’ crop canopy situated within a protected environment such as a large screenhouse. The new model accounts for the vertically distributed sources and sinks within the canopy volume as well as for modifications introduced by the screen on the flow field and microenvironment. The effect of the screen on fetch as a function of its relative height above the canopy is then studied for the first time and compared to the case where the screen is absent. The model calculations agreed with field experiments based on EC measurements from two screenhouse experiments. Implications, both scientific and agricultural The study established for the first time, both experimentally and theoretically, the use of four simple TT techniques for ET estimates within large agricultural screenhouses. Such measurements, along with reliable theoretical models, will enable the future development of lowcost ET monitoring system which will be attainable for day-to-day use by growers in improving irrigation management.
