In this paper, we investigate the intersection signal design problem from a brand-new point and propose a variational inequality model to describe the intersection signal design problem based on the dynamic user optimal state. The cell transmission model is used to model flow propagation through the intersection and obtain the cumulative flow curves, which is consequently used to formulate vehicles' travel delay. A sample intersection is used to illustrate the application of the proposed model and solution algorithm, and some results are got by comparison.
This paper considers the aspect of dynamic routing in a circuit switched network which is not a full connected network. It also presents the theoretical considerations that affect the selection and definition of routes as well as parameters that affect the link resource capacities. In restrictions set in this way imposed by ground/ground (G/G) voice communication in ATM (Air Traffic Management) the solutions of performance for the suggested dynamic routing scheme have been achieved.
KEY WORDS: ATM, GG voice communication, dynamic routing, link capacity dimensioning
This paper discusses a simple theoretical throw model for frontal vehicle-pedestrian collisions. The model is based on the simple assumption that pedestrian movement after impact can be approximated by movement of a mass point. Two methods of reconstruction of vehicle-pedestrian collision are discussed: one knowing only the throw distance and the other when also impact to ground contact distance is known. The model is verified by field data available in the literature and by comportment with full scale numerical simulation.
The future of transport, whatever it will be, cannot be consideredseparately from that of cities. But what, where and whenis the city today? The ability to provide opportunities for humaninteraction is the essential reason for cities to exist. In thepre-industrial past this required high-density, compact urbanforms. Modem transport and communication techniques havehowever increasingly offered human beings ways of interactingat a distance. Physical proximity is no longer needed by manytypes of urban activities. As a result, cities have decentralised,as industry first, then residences and services have fled the diseconomiesof high-density agglomerations. For the future,some even predict the advent of an entirely diffuse, 'virtual' city.Actual evidence is at best mixed. Next to ongoing decentralisation,there are also signals that point in the opposite direction,as there are activities that show a tendency to physicallyconcentrate, underscoring a persistent need for physical humaninteraction. These activities include business and financial services,the emerging sectors of culture, entertainment and themedia, but also certain types of residences and of production.As a result, rather than decentralisation or concentration, contemporarycities show a complex combination of decentralisationand concentration.How will these contrasting movements shape the cities ofthe future? Are telecommunication technologies going to radicallyalter current trends? Or will the quest for sustainability dothis? And what will the role of transp01tation- as cause and effect-be? The diffuse urban-regional accessibility warranted bythe car and the inter-metropolitan connections provided by theaeroplane have been essential conditions for the urbanisationpatterns of the recent past. But will the car and the aeroplanealso be the transportation means of the cities of the future?
Freight transportation constitutes one of the main activities that influences economy and society, as it assures a vital link between suppliers and customers and it represents a major source of employment. Multi-echelon distribution is one of the most common strategies adopted by the transportation companies in an aim of cost reduction. Although vehicle routing problems are very common in operational research, they are essentially related to single-echelon cases. This paper presents the main concepts of multi-echelon distribution with cross-docks and a unified notation for the N-echelon location routing problem. A literature review is also presented, in order to list the main problems and methods that can be helpful for scientists and transportation practitioners.
The basic aim of this paper is to research the importance of supply chain optimization in the circumstances of the COVID-19 crisis. The research object is the optimum selection of active participants before and after the COVID-19 crisis. The initial hypothesis of this paper is that optimal COVID-19-free supply chains can be formed with a dynamic programming method, the costs of which will be higher than those when this restriction would not exist, but significantly lower than those formed if the optimization principle in the selection of supply chain stakeholders would be neglected. Research results in this scientific discussion paper are based on the analysis and synthesis method, comparative method, and dynamic programming method. The main findings of this paper point to the conclusion that the COVID-19 crisis affected the reduction of goods flow within supply chains, reduction of potential participants in supply chains, reduction of supply chains business safety, and increase in business costs.
The aim of this paper is to conduct a spatial correlation study of virus transmission in the Hubei province, China. The number of confirmed COVID-19 cases released by the National Health and Construction Commission, the traffic flow data provided by Baidu migration, and the current situation of Wuhan intercity traffic were collected. The Moran’s I test shows that there is a positive spatial correlation between the 17 cities in the Hubei province. The result of Moran’s I test also shows that four different policies to restrict inter-city traffic can be issued for the four types of cities. The ordinary least squares regression, spatial lag model, spatial error model, and spatial lag error model were built. Based on the analysis of the spatial lag error model, whose goodness of fit is the highest among the four models, it can be concluded that the speed of COVID-19 spread within a certain region is not only related to the current infection itself but also associated with the scale of the infection in the surrounding area. Thus, the spill-over effect of the COVID-19 is also presented. This paper bridges inter-city traffic and spatial economics, provides a theoretical contribution, and verifies the necessity of a lockdown from an empirical point of view.
20.000 km of new railways were built in China in 1988-2002. The railway network has increased its topological complexity from 75 to 112 circuits and the new 3rd topological layer appeared in 1993 and the 4th will emerge in 2004 after the opening of the rail ferry Dalian - Yan-tai. The main features of the recent Chinese rail network are: 1) the predominance of meridional-ity, 2) the spatial disproportion between the eastern coastal area (with dense network) and the empty western part, 3) the low level of electrification (20%) and the low share of double-track sections (30%), 4) the land-lock orientation of the whole network and a small number of lines along the sea coasts. These disproportions are the main obstacles for a harmonic spatial devel-opment of the economic structure.
Because of the advantages of turboshaft engine condition trend monitoring, it is in the interest of the Croatian Air Force to examine its applicability in Bell 206B III helicopter maintenance system. The paper deals with the basic of turboshaft engine condition trend monitoring procedure; and describes also the procedure for Allison 250 C20J engine, which is installed in Bell 206B III. Results of parameter readings are presented and reasons of inapplicability of condition trend monitoring within pilot training process are explained. Alternative procedure is recommended.
Natural gas is relatively cheap, environmentally friendly and energetically efficient fossil fuel that is gaining in attractiveness daily as it can be used in many sectors. As not all consumers can be reached by pipelines the technique of transporting natural gas in the liquefied form has been developed at the beginning of 20th century but it was only in 1959 that the first overseas transport of liquefied natural gas (LNG) occurred. In the fifty years of operation LNG shipping has shown immaculate safety records. LNG tankers can be described only in superlatives; they are without any doubt the most sophisticated and expensive ships that sail around the globe, they demand special attention when navigating to or out of harbours and need to be manned with the most educated and experienced crew. LNG market is expanding and changing; demand is surpassing the productivity, new importing and exporting countries appear, LNG fleet is growing in capacity and number at high pace, exploitation contracts for the ships are being modified giving the opportunity for new companies to enter (...). The paper gives an overview on liquefied natural gas market and the historic development of LNG shipping. It focuses on the recent boom in LNG shipping and emphasises questions concerning the safety, crewing and exploitation of the LNG tankers in the future.
The development of logistics has contributed a lot to all the branches of economy. A successftd economic subject cannot exist without a well-developed logistic branch. In economics the organization of logistics is becoming a strategic element regarding the policy making of enterprises. Logistics belongs to an area that will play an important role in our lives; therefore, the development of a logistic system is of an exceptional significance for the economy and also for the non-economic sphere of activities. So, modern logistics enables us to bring into line different interests in management of material current. Global organizers of logistic services are developing and specializing in some essential services, such as combining of cargo into assembly consignments and also their distribution. The biggest global tenderers of logistic services are considered, DHL, TNT, FEDEX, UPS.
On the basis of relevant scientific research this paper systematically and concisely elaborates the interaction between intellectual capital and logistic services production. Full attention is given to intellectual capital as a factor in effective creation of the logistic processes or in other words, to prove the statement that the first place for achieving competitive advantages in the global and/or regional market of logistic services belongs to knowledge used to produce or improve the existent logistic systems and to create new ones. Further, the paper deals with the tasks of creative logistic managers as open, dynamic and stochastic systems based on knowledge or the creation of universal logistic model determined by the fact that intellectual capital and technological paradigm create the way to new logistic paradigm. Special attention is paid to building and presenting a mathematical model for measuring the intellectual capital as well as the success of its use in different logistic companies.
Although an "avalanche of people" may be expected in the near future little confidence scents to be justified with respect to a peaceful and prosperous development in the Near East. Political antagonism, often fuelled by religious intolerance threatens or even prevents the evaluation of promising opportunities at this huge area between the Old World continents which could otherwise benefit so much from the by-passing great world traffic routes.
The remarkable rise of Europe following the Napoleonic Wars during the early 19th century favouring the spread of the railway systems and - subsequent to this new mode of transport - leading to almost complete industrialisation and urbanisation in the political frame of nation states has suffered severe set-backs during the 20th century deplorably highlighted by World War I and World War II, by various civil wars and the Cold War, by large scale expellations, and substantial alternations of political borders. At the same time much has changed, too throughout the extensive continental regions around Europe. Consequently, prospects for future development in the 21st century differ widely. Extraordinary effort is demanded to satisfy social expectations not known so far avoiding, however, both new warlike conflicts and additional exploitations of the natural environment. To solve this task traffic plays a key role by optimal evaluation of all its modes and by application of the best technical achievements along with stepwise adaptation of the urban settlements which represent the most important locations of living and working.
The probability that an individual will be involved in a car accident is relatively high. Traffic safety is a global problem, and Slovenia is no exception. Despite the large improvement in traffic safety records, Slovenia still ranks very low on the European level with 63 fatalities per million inhabitants. The paper analyses the official data on traffic accidents in Slovenia in the period from 1999 to 2011. The paper presents an overview of road safety in Slovenia with emphasis on the participation of young people in severe accidents. It has been examined whether young people in Slovenia are the most dangerous and at the same time the most vulnerable category of road users and the causes of road accidents involving young people have been compared with the causes of accidents involving overall population.
This paper compares the user experiences (UXs) while riding a scooter on the road to watching a 360° immersive scooter ride video in a laboratory using a Head-mounted Display (HMD) projection system. The aim of this study is to determine whether watching through an HMD projection system produces similar feelings of attractiveness, practicality, and enjoyment for the riding experience as riding on a real scooter. The data were collected from an experiment involving a total of 59 individual scooter commuters. The participants were asked to watch a 360° immersive video and to complete a user experience questionnaire (UEQ). The results verified that a virtual reality (VR) service with an HMD and panoramic scooter riding video content may be used as an experience tool to create reality-like scooter riding experiences for the users. Furthermore, the important factors that influence a user’s continued usage of watching 360° immersive video services were found to be attractiveness and pragmatic quality. Based on these results, a number of suggestions are proposed for the design of related VR services to strengthen the advantages of 360° immersive video in simulated two-wheeler ride experiences and providing road safety education.
Traffic accidents in road traffic are becoming an increasing problem regardless of whether there is only material damage or serious injuries and fatalities. There are various causes resulting in traffic accidents, and this paper describes the reconstruction work on a section of the motorway in order to improve the traffic safety. Also, the results of the given reconstruction have been analysed.
Using generalised systems methodology, the paper considers the approach to effective functional integration of transport and telecommunications technology in solving mobility problems. Basic functions and structure of third generation of wireless systems (3G) are evaluated from the aspects of traffic technology. The paper elaborates how increased accessibility and reliable broadband capabilities of 3G systems combined with Internet application can improve the existing teletraffic technologies. Evolutionary network migration to 3G networks has been suggested as an effective strategic choice for mobile operators.
To resolve the problem of future airspace management under great traffic flow and high density condition, 4D trajectory estimation has become one of the core technologies of the next new generation air traffic control automation system. According to the flight profile and the dynamics models of different aircraft types under different flight conditions, a hybrid system model that switches the aircraft from one flight stage to another with aircraft state changing continuously in one state is constructed. Additionally, air temperature and wind speed are used to modify aircraft true airspeed as well as ground speed, and the hybrid system evolution simulation is used to estimate aircraft 4D trajectory. The case study proves that 4D trajectory estimated through hybrid system model can image the flight dynamic states of aircraft and satisfy the needs of the planned flight altitude profile.