Сучасні методи дослідження нелінійних коливань

(ru) Рассмотрены колебания консервативной системы. Предложен метод численного отыскания периода колебаний. Исследуются также колебания в нелинейных системах, рассматривается проблема центра-фокуса, получено численное решение дифференциальных уравнений и построены фазовые траектории. Рассмотрено уравнение Ван дер Поля и методы его исследования.(en) The vibrations of the conservative system are considered. The method of the numeral searching of period of vibrations is offered. Vibrations are also probed in the nonlinear systems, the problem of center-focus is examined, got numeral decision of differential equklizations and phase trajectories are built. Equklization of Van der Paul and methods of his research is considered

Сравнительный анализ методик количественного определения окалинообразования в металлургическом переделе

Материалы XIII Междунар. науч.-техн. конф. студентов, магистрантов и молодых ученых, Гомель, 25–26 апр. 2013

Towards safe and efficient shared-space oriented DRT Service – some insights with real case study in Linköping

With the expeditious development in technology autonomous vehicles (AVs) are going to become a part of our daily life. Their possible influences on current transportation systems and the needs of the future traffic systems with the introduction of AVs have been investigated extensively with use of traffic simulation tools. Apart from simulative studies more and more real-life demonstrations of AVs are carried out and real AV data becomes available. The latter one facilitates to further properly model AVs’ driving behaviour in traffic simulation. Related AVs’ impact evaluations can then be more representative and support policy and decision making. In this paper, real autonomous shuttle bus data is analysed to understand driving situation, to derive vehicle-related parameters for enhancing microscopic traffic simulation model, and to find out possible issues in real traffic environment

Automation-ready framework for urban transport planning

The mission of the H2020 CoEXist project is to enable mobility stakeholders to get “Automation-ready” – which CoEXist currently defines as conducting transport and infrastructure planning for connected and automated vehicles (CAVs) in the same comprehensive manner as for existing modes such as conventional vehicles, public transport, pedestrians, and cyclists, while ensuring continued support for existing modes on the same network. This definition will be fine-tuned through stakeholder engagement processes. The H2020 CoEXist project started in May 2017 and will run until April 2020. This paper introduces this project and covers its progress until January 2018, with a focus on the methodology of the “Automation-ready framework” that provides a planning framework for urban road authorities to prepare for the introduction of CAVs on the road network. The framework includes elements about strategic urban mobility planning for CAVs and a clear guide for urban transport planners with a list of concrete actions that cities can do now to plan for CAVs on their road network

A model for simulation and generation of surrounding vehicles in driving simulators

Driving simulators are used to conduct experiments on for example driver behavior, road design, and vehicle characteristics. The results of the experiments often depend on the traffic conditions. One example is the evaluation of cellular phones and how they affect driving behavior. It is clear that the ability to use phones when driving depends on traffic intensity and composition, and that realistic experiments in driving simulators therefore has to include surrounding traffic. This thesis describes a model that generates and simulates surrounding vehicles for a driving simulator. The proposed model generates a traffic stream, corresponding to a given target flow and simulates realistic interactions between vehicles. The model is built on established techniques for time-driven microscopic simulation of traffic and uses an approach of only simulating the closest neighborhood of the driving simulator vehicle. In our model this closest neighborhood is divided into one inner region and two outer regions. Vehicles in the inner region are simulated according to advanced behavioral models while vehicles in the outer regions are updated according to a less time-consuming model. The presented work includes a new framework for generating and simulating vehicles within a moving area. It also includes the development of enhanced models for car-following and overtaking and a simple mesoscopic traffic model. The developed model has been integrated and tested within the VTI Driving simulator III. A driving simulator experiment has been performed in order to check if the participants observe the behavior of the simulated vehicles as realistic or not. The results were promising but they also indicated that enhancements could be made. The model has also been validated on the number of vehicles that catches up with the driving simulator vehicle and vice versa. The agreement is good for active and passive catch-ups on rural roads and for passive catch-ups on freeways, but less good for active catch-ups on freeways

Simulation of Surrounding Vehicles in Driving Simulators

Driving simulators and microscopic traffic simulation are important tools for making evaluations of driving and traffic. A driving simulator is de-signed to imitate real driving and is used to conduct experiments on driver behavior. Traffic simulation is commonly used to evaluate the quality of service of different infrastructure designs. This thesis considers a different application of traffic simulation, namely the simulation of surrounding vehicles in driving simulators. The surrounding traffic is one of several factors that influence a driver's mental load and ability to drive a vehicle. The representation of the surrounding vehicles in a driving simulator plays an important role in the striving to create an illusion of real driving. If the illusion of real driving is not good enough, there is an risk that drivers will behave differently than in real world driving, implying that the results and conclusions reached from simulations may not be transferable to real driving. This thesis has two main objectives. The first objective is to develop a model for generating and simulating autonomous surrounding vehicles in a driving simulator. The approach used by the model developed is to only simulate the closest area of the driving simulator vehicle. This area is divided into one inner region and two outer regions. Vehicles in the inner region are simulated according to a microscopic model which includes sub-models for driving behavior, while vehicles in the outer regions are updated according to a less time-consuming mesoscopic model. The second objective is to develop an algorithm for combining autonomous vehicles and controlled events. Driving simulators are often used to study situations that rarely occur in the real traffic system. In order to create the same situations for each subject, the behavior of the surrounding vehicles has traditionally been strictly controlled. This often leads to less realistic surrounding traffic. The algorithm developed makes it possible to use autonomous traffic between the predefined controlled situations, and thereby get both realistic traffc and controlled events. The model and the algorithm developed have been implemented and tested in the VTI driving simulator with promising results

Linköping studies in science and technology. Dissertations

Abstract Driving simulators and microscopic traffic simulation are important tools for making evaluations of driving and traffic. A driving simulator is designed to imitate real driving and is used to conduct experiments on driver behavior. Traffic simulation is commonly used to evaluate the quality of service of different infrastructure designs. This thesis considers a different application of traffic simulation, namely the simulation of surrounding vehicles in driving simulators. The surrounding traffic is one of several factors that influence a driver's mental load and ability to drive a vehicle. The representation of the surrounding vehicles in a driving simulator plays an important role in the striving to create an illusion of real driving. If the illusion of real driving is not good enough, there is an risk that drivers will behave differently than in real world driving, implying that the results and conclusions reached from simulations may not be transferable to real driving. This thesis has two main objectives. The first objective is to develop a model for generating and simulating autonomous surrounding vehicles in a driving simulator. The approach used by the model developed is to only simulate the closest area of the driving simulator vehicle. This area is divided into one inner region and two outer regions. Vehicles in the inner region are simulated according to a microscopic model which includes sub-models for driving behavior, while vehicles in the outer regions are updated according to a less time-consuming mesoscopic model. The second objective is to develop an algorithm for combining autonomous vehicles and controlled events. Driving simulators are often used to study situations that rarely occur in the real traffic system. In order to create the same situations for each subject, the behavior of the surrounding vehicles has traditionally been strictly controlled. This often leads to less realistic surrounding traffic. The algorithm developed makes it possible to use autonomous traffic between the predefined controlled situations, and thereby get both realistic traffic and controlled events. The model and the algorithm developed have been implemented and tested in the VTI driving simulator with promising results. iii Populärvetenskaplig sammanfattning Den här avhandlingen handlar om att kombinera mikroskopisk trafiksimulering och körsimulatorer. Mikroskopisk trafiksimuleringär ett viktigt verktyg som framförallt används för att analysera olika förslag till förändringar i vägtrafiksystemet. Det kan handla om att jämföra olika korsnings-och vägutformningar eller trafiksignalsstrategier. I en mikroskopisk trafiksimuleringsmodell simuleras enskilda förar-fordonsenheter. Simuleringen bygger på delmodeller som beskriver hur förare accelererar, när de väljer att byta körfält, vilken hastighet de vill köra i, med mera. En körsimulatorär en modellkonstruktion som ska efterlikna verklig bilkörning. Föraren kör fordonet på samma sätt som ett riktigt fordon, medan den omgivande trafikmiljön simuleras. En körsimulator kan liknas vid ett avancerat datorbilspel. Körsimulatorer används bland annat för att studera förarbeteende. Den omgivande trafikmiljön spelar en viktig roll i arbetet med att skapa en illusion av verklig bilkörning. Om inte illusionenär tillräckligt bra finns en risk att testpersonerna kör annorlunda i körsimulatorn jämfört med hur de kör i verklig trafik. I den här avhandlingen presenteras en modell för att generera och simulera omgivande trafik i en körsimulator. Modellenär baserad på mikroskopisk trafiksimulering. Körsimulatorer används ofta för att studera situationer eller händelser som sällan förekommer i det verkliga trafiksystemet, till exempel trafiksäkerhetskritiska händelser. För att säkerställa att alla försökspersoner kör under samma förutsättningar brukar de omgivande fordonens beteende strikt kontrolleras. Detta gör det möjligt att utsätta samtliga försökspersoner för samma situationer. Det medför dock ofta att de omgivande fordonen beter sig mindre likt verkliga bilförare. Genom att använda en mikroskopisk trafiksimuleringsmodell kan realismenökas. Detta medför dock att förutsättningarna på detaljnivå kommer att skilja sigåt mellan försökspersonerna samt att detär svårare att utsätta förarna för förutbestämda situationer. För att lösa detta har en modell som kan växla mellan simulerad trafik och förutbestämda situationer utvecklats. De utvecklade modellerna har implementerats och testats i VTIs körsimulator med lovande resultat.

Calibration of volume delay functions : Suggestions for method and data collection approaches

Vid ruttvals- och restidsberäkningar i statiska nätutläggningsprogram (Emme, Visum, TransCad) används så kallade restidsfunktioner. Sambanden beskriver hur restiden beror av trafikvolymen för olika typer av vägar. Dessa restidsfunktioner är en av grundbultarna i persontransportmodeller som det svenska Sampers-systemet. Detta notat redovisar en förstudie med syftet att undersöka hur restidsfunktionerna i det svenska Sampers-systemet bör utformas och kalibreras. Detta innefattar hur vägklassindelningen bör göras, vilken typ av funktioner som ska användas, hur de ska kalibreras och vilken data som behöver samlas in för kalibreringen. För att undersöka detta genomfördes: en litteraturstudie för att utröna state-of-practice; workshops för att fånga upp användares erfarenheter av de nuvarande svenska restidsfunktionerna; workshops med experter på datainsamling för att diskutera mest lämpliga datakällor och datainsamlingstekniker; samt projektinterna diskussioner kring olika kalibreringsansatser och metoder. Litteraturstudien visade att det finns få riktlinjer om hur restidsfunktioner bör eller ska kalibreras. Vanligtvis har parametrarna kalibrerats genom kurvanpassning mot punktmätningar av flöde och medelhastighet. Det finns några exempel där kalibreringen baserats på restidsmätningar med ”floatingcar” eller restidskameror. Baserat på tidigare genomförda studier i Sverige och den genomförda litteraturstudien konstateras att restidsfunktioner som ger en bra beskrivning av trafikföringen på enskilda länkar inte nödvändigtvis ger en bra överenstämmelse av modellberäknade och uppmätta flöden och restider. För att motverka detta har det i litteraturen föreslagits och testats kalibreringsmetoder där kalibreringen av parametrarna genomförs med hjälp av optimeringsalgoritmer med syftet att minimera skillnaden mellan modellberäknade och uppmätta länkflöden och restider. Baserat på litteraturstudien och diskussioner i projektgruppen så är slutsatsen att en sådan ansats bör undersökas. För att undvika överkalibrering och orimliga parametervärden bör möjliga parametervärden begränsas. För kalibreringen behövs både länkflödesobservationer och restidsobservationer. Länkflödesobservationer genomförs återkommande för andra syftet och kan hämtas från Trafikverkets och kommunernas ordinarie trafikmätningar. Restidsdata föreslås hämtas från de upphandlingar av inköp av restidsdata som Göteborgs och Stockholms stad genomfört tillsammans med Trafikverket. Förstudien rekommenderar Trafikverket att också undersöka möjligheten att köpa in restidsdata för större delen av sitt huvudvägnät.Route choice calculations in static traffic assignment models (as Emme, Visum, TransCad) are based on travel time estimations using volume delay functions. The volume delay function (also denoted travel time functions) describe how the travel time depend on the traffic volume for different types of roads. The volume delay functions are one of the base elements in travel prognosis models as the Swedish Sampers model system. This report presents a pre-study with the aim to investigate how volume delay functions should be designed and calibrated, including which road classification to use, which type of volume delay function that should be used, how the functions should be calibrated and which data that is needed for the calibration. These questions were investigated by a literature review on state-of-practice, workshops with experienced Sampers users to collect information and experiences of the current volume delay functions in Sampers, workshops with research experts on data collection of travel times, and project internal discussions on calibration methodologies. The literature review showed that there are few guidelines on how volume delay functions can or should be calibrated. The calibration is commonly conducted by fitting the volume delay function curve to cross-sectional measurements of flow and mean speed. There are some examples of calibration based on travel time measurements based on floating car measurements or number plate recognition. These calibration approaches focus on describing travel time for a given link based on the flow at the link. However, based on the literature review and experience from earlier research in Sweden it is concluded that volume delay functions that represent the traffic process on a road link in a good way do not necessary give a good fit of the static assignment calculated and observed link and route flows and travel times. There are several attempts described in the literature of calibration approaches that aim to minimize the difference between model calculated and observed flows and travel times using optimization techniques. The suggestion from the pre-study is that such an approach should be investigated for calibration of the Sampers volume delay functions. To avoid overfitting and unrealistic parameters values the optimization should include lower and upper limits of the parameters. The calibration requires both link flow and travel time observations. Link counts are regularly measured for other purposes and can be collected from the Swedish Transport Administration and municipality regular traffic measurement programs. The suggestion for travel time data is to use the travel time data that currently is commissioned by the Swedish Transport Administration and Stockholm and Göteborg municipality. Our recommendation is also that the Swedish Transport Administration investigate the possibility to buy travel time data for the Swedish main road network.Förstudie kring framtagning av fördröjningsfunktioner för vägtrafik till SAMPER