Computer supported estimation of input data for transportation models

Control and management of transportation systems frequently rely on optimization or simulation methods based on a suitable model. Such a model uses optimization or simulation procedures and correct input data. The input data define transportation infrastructure and transportation flows. Data acquisition is a costly process and so an efficient approach is highly desirable. The infrastructure can be recognized from drawn maps using segmentation, thinning and vectorization. The accurate definition of network topology and nodes position is the crucial part of the process. Transportation flows can be analyzed as vehicle’s behavior based on video sequences of typical traffic situations. Resulting information consists of vehicle position, actual speed and acceleration along the road section. Data for individual vehicles are statistically processed and standard vehicle characteristics can be recommended for vehicle generator in simulation models

GENERAL MODEL OF A TRANSPORTATION SYSTEM

Dopravní systémy jsou zpravidla rozsáhlé, geograficky distribuované systémy. Zahrnují různé druhy dopravy (v našich podmínkách zejména silniční a železniční dopravu, kombinovanou dopravu a vnitropodnikovou resp. mezioperační dopravu). Pro všechny druhy dopravy můžeme řešit úlohy řízení a optimalizace procesů od řízení vozidel a dopravních proudů až po optimalizační úlohy plánování dopravních služeb a řízení provozu na dopravní síti. Model dopravního systému vyžaduje množství vstupních údajů, jejichž pořizování je nákladné a proto je třeba získané údaje dokonale využít. Univerzální model dopravního systému může všestranně využívat vstupní údaje a sloužit pro množství aplikací bez ohledu na zvláštnosti každého druhu dopravy, na rozdíl mezi úrovněmi podrobnosti modelu a na typu řešené úlohy řízení. Vhodným nástrojem pro tvorbu takového modelu je objektově orientované programování používající virtuální metody, polymorfizmus a dědičnost objektů. V příspěvku jsou ukázány zkušenosti z budování univerzálního modelu dopravního systému a souvisejících optimalizačních metod jak z oblasti matematického programování tak z oblasti řízení dynamických procesů a simulace dopravních a logistických systémů.Transportation systems are large distributed system. They may deal with various transportation modes (like road or railway transport, combined transports and transport in factories and production plants). Control and optimization problems from control of individual vehicles and transportation flows to optimization of transportation services and traffic in transportation networks are to be solved in all mentioned transportation systems. Model of the transportation system needs vast and expensive input data which should be possibly well exploited. A universal model of the transportation system can use the input data for a variety of applications without any regard to transportation mode, to differences in the detailed model description and to type of the optimization problem. A suitable tool for creating such a model is object oriented programming using virtual methods, polymorphism and inheritance of objects. The paper presents some experience in building such universal models and corresponding optimization methods of mathematical programming as well as methods of automatic control and simulation of transportation and logistic systems

The Physical model of transportation flow

Článok ukazuje kinematickú teóriu dopravného prúdu založenú na modeli dynamiky pohybu dopravného prostriedku a na hypotézách správania vodiča. Odvodené výsledky ukazujú, že kinematický model podľa očakávaných hypotéz správania dáva výsledky súhlasné s experimentálne zistenými hodnotami a preto môže slúžiť ako prostreidok pre skúmanie chovania dopravného prúdu pre rôzne stupne zaťaženia dopravnej komunikácie

A Contribution to the Traffic State Estimation by Means of Image Processing

The success of traffic simulations depends largely on the simulation model validity and on accuracy of input data. For input data acquisition, video cameras are used to survey the traffic at junctions or at other places along the road to collect video data. The velocity, distance between the vehicles, acceleration and other relevant parameters can be extracted from the collected data. The estimated values are used for calibration of the simulation model. The data that has to be collected for calibration or validation of the simulation system, differ from country to country and reflects the driver behavior. For that reason, the data collection must be performed and the simulation system calibrated, each time when modeling a different traffic area. The more accurate the obtained parameters, the more accurate the traffic simulation would be. The image processing methods and the expected accuracy of traffic state estimation, such as vehicle position, speed and acceleration, is discussed in the paper and applied to the evaluation of driver behavior necessary for the calibration of the microscopic simulation systems

Optimalizace státní správy a územněsprávního členění

A government and local authorities should serve citizens and provide acceptable services for them. Planning and organisation of such public services must respect a limited budget and must ensure an appropriate quality of offered services. The quality of the services depends also on their accessibility, which means that the citizen must travel to a centre where the service is available. The optimal location of centres should thus respect the accessibility, as one of the criterion and the solution should offer the services equally accessible to all citizens at possibly low costs. The optimisation of regional centre allocation in Slovakia was tried using an optimisation model of centres location

Where Brain, Body and World Collide

The production cross section of electrons from semileptonic decays of beauty hadrons was measured at mid-rapidity (|y| < 0.8) in the transverse momentum range 1 < pt < 8 Gev/c with the ALICE experiment at the CERN LHC in pp collisions at a center of mass energy sqrt{s} = 7 TeV using an integrated luminosity of 2.2 nb^{-1}. Electrons from beauty hadron decays were selected based on the displacement of the decay vertex from the collision vertex. A perturbative QCD calculation agrees with the measurement within uncertainties. The data were extrapolated to the full phase space to determine the total cross section for the production of beauty quark-antiquark pairs