2005, VOLUME 6 #2. "TRANSPORT AND TELECOMMUNICATION". SCIENTIFIC & RESEARCH JOURNAL OF TTI, ISSN 1407-6160
The aim of the journal is to acquaint the readers with the national experience and research activities of various countries in the fields of transport and telematics as well as with the working materials of the European thematic networks and the research projects in this area. This special edition is devoted to the International Conference "Reliability and Statistics in Transportation and Communication" (October 14-15, 2004, Riga, Latvia). The edition includes texts of conference reports written by the authors in a special journal version. The authors have submitted the material in English or Russian in accordance with the official languages of the Conference. Therefore, for the convenience of readers the editorial board has divided the selected materials into three editions - English (Vol.6, No1, No2, 2005) and Russian (Vol.6, No3, 2005).
Journal in Journal: Proceedings
- Title List of the Proceedings
- The Programme Committee and Organization Committee
- Programme of the Conference
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Session 4. Reliability of Aviation and Mechanical Systems
This paper is devoted to the discussion and solution for the following problems: Determination of mean value and variance of estimates of parameters of fatigue crack growth model for both the corroded and noncorroded types of specimens: a (0), ?, ln Q and m. Inspection modelling with the use of Monte Carlo method for calculation of probability of fatigue failure as function of inspection number. Determination of the number of inspections required for the limitation of fatigue failure probability. Comparison of the required for required reliability) is ninsp for corroded and non-corroded cases. Special programs have been developed for necessary calculations. It was confirmed that the influence of corrosion has a great impact on the required number of inspections.
Keywords: fatigue crack growth, corrosion medium, failure probability, inspection program & specified life
To study the fatigue crack growth problems and to emphasize the variability of the growth curves in addition to their average growth trend, four stochastic fatigue crack growth models are presented. These models include the Markov chain model, Yang's power law model, the polynomial model and a probabilistic log-linear fatigue crack growth model with the parameter that varies from unit to unit according to a Weibull (?,?), lognormal or normal distribution. Experimental work can be carried out to produce the required fatigue crack growth data, which are then used for verification of the models. It is found that all these models can be used to depict the experimentally obtained fatigue crack growth data with certain degrees of accuracy. However, out of the four models, one is superior to the others concerning a certain data set while the other three models are better for other data sets. As soon as the appropriate stochastic model is established, it can be used for the fatigue reliability prediction of structures made of the tested material.
Keywords: fatigue crack growth, stochastic model, random process, probabilistic analysis
The dynamic processes in the drive together with the asynchronous engine, coupling with gas, and mechanical drive are considered in this article. The coupling of this type consists of separate segments, where additional masses are input. There is presented dynamic model of drive pressure wave propagation in gas, interaction of separate coupling bodies and gas in the article. Gas movement in segments is described by the equations of continuity, movement quantity and gas state. This system of equations is solved by the method of characteristics together with the system of equations of asynchronous engine and mechanical drive; the received non-linear equations are solved by Newton method.
Keywords: mechanical and pneumatic system, pressure wave, asynchronous engine, numerical method, simulation
The article analyses the homogeneity problem of asphalt concrete mixture (ACM) used in road pavement. The average values of an ACM lot composition and physical-mechanical parameters shall comply with the requirements of the project and standards. Another important factor is that the amount of components in separate ACM batches influencing on the homogeneity of the lot's structure and characteristics would fluctuate within the minimum narrow interval. The variation interval of coarse aggregate, fine aggregate and fillers' amount in ACM and its grading in the lot is influenced by the stability of the materials' grading used when producing the mixture.
When simulating different variation of mineral materials' grading mathematically, the scattering of the ACM grading produced of them is simulated. While applying the theoretical principles of the simulation, formulas were written and software was developed, which enabled to design ACM from mineral materials of different homogeneity, the quality of which is shown not by one curve of grading but the wholeness of curves laid out on the interval of relevant width.
When changing the grading varying according to the normal distribution of cold imported fillers, reclaimed dust and five hot fractions aggregate of different coarseness, screened in the asphalt concrete mixing plant, the statistical characteristics of ACM composition and components' quality scattering are obtained. The presented methodology of mathematical simulation also enables to calculate the scattering of all used mineral materials' grading according to the (set) permitted ACM grading variation interval in the lot. The mathematical programming method was applied in the proposed methodology; software was developed and the calculated experiment was carried out.
Keywords: asphalt concrete mixture, grading, homogeneity, mathematical simulation, mathematical programming
Public transportation system often transport disabled individuals seated in wheelchairs, and there must be certain means to safely secure them. In present paper the dynamical behavior of the dynamic "Man - Wheelchair - Vehicle" system under the action of external excitation is analyzed. Main characteristics of the external excitation during the motion of the public transport were determined by experimental measurements of the acceleration. The analysis of the frequency spectrum of the moving vehicle and wheelchair-seated disabled person was performed and coincident resonant frequencies in low range were noted. The dynamical and mathematical models of the disabled person seated in a wheelchair were developed and three possible cases of the dynamic system's motion were described; they are the steady motion, partial and complete abruption cases. Numerical analysis of the system's dynamical stability was performed.
Keywords: wheelchair, transportation safety, public transport, external excitation, disabled persons, dynamic system
Session 5. Efficiency of Electronics Systems and Devices
The new method of recursive systems identification is suggested. The results of super-narrow band filters modelling are shown.
Keywords: narrow-band digital filters, identification, characteristic verification
To raise the efficiency of short wave communication lines in civil aviation it is suggested to use ferricelectrical antennae of zenithal radiation and reception as antennae for aircraft. Some types of these antennae have been considered in the given article. There has been got the expression for an average diagram of the direction of the receiving antenna system in power and with the account of experimentally collected statistic characteristics of signals for short trajectories.
Keywords: ferric-electrical antennae, receiving antenna system, statistic characteristics
Numerically effectiveness of receiving antenna characterizes threshold sensitivity. In the work were obtained the expressions for threshold sensitivity of receiving electrical and ferrite antennae. Expressions make it possible to compare these antennae between themselves. It is shown that the receiving ferrite antenna on comparing with the electrical antenna is more effective under the conditions of acting of different interferences, which have, in essence, electrical character. Such interferences include the industrial interferences and those interferences, caused by the reflection from the objects, which are located near the receiving antenna.
Keywords: receiving antenna, effectiveness, threshold sensitivity
Session 6. Transport
An analysis of the passenger service market and today situation of passenger long-distance travel in Lithuania shows that the main weakness is as follows - an absence of the organized passenger intermodality in the country. The strengths - county's favourable geographic position, needs of the international trips, good conditions of road, air and water transport infrastructure - stimulate to improve the quality of passenger conveyance and to organize the intermodal service network. The investigation of different modes of passenger transport shows the possibilities for the cooperation in the integrated service market. Some combination of separate traffic modes exists in the field of combination timetable of regular buses to the train schedule in the regional centres and small towns. Another type of intermodality exists in urban public passenger transport system harmonization. The changers of the demand are going to the development of passenger market. Social-economic possibilities of population are increasing every year. But financial potential of population is arising slowly, so demand for the international passenger transport is lower than in other countries. The best opportunity to implement the intermodal passenger transportation is the organization of good interface with EU level passenger transport network, integration into the international passenger service market.
Keywords: passenger transport, intermodality, long-distance travellers, use of different modes, modal conflicts
The article covers an analysis of passenger transportation by Lithuanian sea transport and trends of development of this transportation. Furthermore, the analysis of passenger transportation by ferries in the Baltic Sea is given - volumes of transportation, operators, and income sources.
Keywords: sea transport, port, ferry line, passenger transportation
Lithuania is a transit country, and one of the main bases for transporting the used cars for Russia Federation and Asia countries. Statistics shows us that solely in 2003 year the registration of motor transport vehicles was made for 1 580 476 units, trucks - 156 326. More then 80 000 units of motor transport vehicles are 15 till 20 years old. Such a problem we have here, because those vehicles from 15 till 20 years old are approximately of 1 million units. Old agriculture machinery is not of economy because of rise in prices of diesel fuel. Agricultural implements and machinery will not be long exploited in the future, because it's not economic and not the way of production exploitation, which makes agriculture production prices up. And all those transport and machinery waste and dismantling of it - Lithuania will have to take care according to the standards of the EU directives. The manufacturers and consumers for unfit in use automobiles and their exploitation materials has to be stimulated to do recovering and second using. The government has to create preventive steps for the waste avoiding. The financial responsibility for unfit in use transport vehicles has to take on the correct manufacturers, in that way Lithuanian citizens will not have to pay the taxes. The place of dismantling transport vehicles could promote transport waste expenses decreasing and mainly controlling this process on places. The principled scheme of the place of dismantling transport vehicles is created and showed.
Keywords: transport vehicles, waste, exploitation materials, perspectives, treatment, automobiles
In present, various means that enable to avoid a crash are rapidly spreading in vehicles. One of such technologies is anti-lock braking system (ABS). In the present Paper, the importance of the anti-lock braking system and its impact on braking distance of a car on wet asphalt are being analysed. During the tests, the speed of movement, braking distance and brake pedal stressing force of two vehicles (with and without ABS) had been fixed. The importance of using of ABS, its advantages and imperfections are discussed on the base of the results of the said experience.
Keywords: anti-lock braking system, vehicle, braking distance
After restoration of Lithuania's independence the industry shifted from a highly structured and regulated industry to an industry operating in market conditions. Global supply chains extended for thousands kilometres. The new thinking about logistics services spread to all logistics suppliers of the companies. It is the significant shift from transaction driven system to continually driven system to all business sectors and for the significant share of third party services providers.
Keywords: logistic, logistics service, third party logistics service, efficiency
The aim of the article is to analyse evolution of freight transportation by Lithuanian railways as well as market development opportunities, to foresee perspectives of transportation activities and to present forecast of freight transportation up to 2020. Based on the analysis of development indicators of the Lithuanian railway transport sector in 1997-2003, the SWOT analysis was carried out. The most important factors and premises that form a basic foundation for the long-term railway transport strategy were identified. In order to form a perspective, the study was based on macro-economical indicators of the
Lithuanian economy, of their evolution and forecasts. Also, external and internal factors having impact on the evolution of freight transportation were analysed; perspective directions were put forward, as well as possible risk factors were identified.
Keywords: railway transport, freight transportation, strategy, forecast
Session 7. Information Technology in Transportation and Education
The coherence of database management systems' schemes and restructured dangerous freight transportation regulations' base theoretically and with certain examples is shown in the article. Regulations of dangerous freight transportation are modelled till the indivisible level so that they wouldn't have any exceptions and references to other regulations. Basis of regulations about transported dangerous freight, their amounts have to be formulated in this way. Transportation of freight and formulation of regulations concerning their conditions in the database have to be separated from conventionality of changing software.
The result of restructure is presented in this article - different types of formal lists of elementary regulations, their creation and changing principles as well as database structure and algorithm for database.
Keywords: dangerous freight, transportation regulations, management system, database
The activities of the Information systems (IS) of Lithuanian Railway, the fields of activities and function of Lithuanian railway and investments to the information system are showed in figures in the article.
The stages of implementing information technologies are showed; the interdepartmental collaboration assessment and common use of IS with other countries are showed as well.
Keywords: information system of Lithuanian railway, transport means, technical characteristics, technological dates, and implemented information systems
Session 8. Computing Mathematics
There is covered a method of request waiting time on-line control for a node of computer network comprising of general memory of limited capacity and multiprocessor computing unit. As a result of synthesis there had been designed an algorithm of current request holding time calculation taking onto account variation of the node operating conditions and requirements on allowable waiting time of requests. On the basis of the holding time evaluation there is calculated the number of required processors for each step of on-line control.
Keywords: waiting time method, online control, algorithm
Discussion Panel. Development of Transport Logistics in the Baltic States
It is identified that the creation of regional logistics centres in Lithuania will have positive impact to the economical development of the country. Logistics centres in Kaunas, Vilnius and Klaipeda will be established under the contemporary requirements and will provide the needed co-operation with big trading companies and other logistics centres in and outside Europe. Existing transport corridors will have significant impact on the business linked as to the separate regions and to the whole country. An increase of international transit traffic will be also related to the complementary and boosting activities of logistic services associated with the development of logistics centres network in Lithuania.
Keywords: logistics centres, transport, costs, economics, development, cargo
The analysis of development of Logistics Centres (LC) shows that these Centres play an important role for the future development of the freight transport and for the economic development of the areas in which they are located. Also the analysis has shown that the logistic synergies developed in the LC are a key factor for the improvement of intermodal transport; the integration of the intermodal terminal into the LC, the proximity of different transport and logistic activities and the services.
But in the countries where to create Logistic Centres is planned, there is not enough of available experience. These countries, including Lithuania, must evaluate the main characteristics for establishment of LC. These characteristics for establishment of Logistics Centres with European and regional importance are: location at a TEN corridor, high class motorway and railway, large span of activities, considerable volume of distribution, network cooperation, cooperation between centres, membership of Euro platforms and organization in a legal body to ensure a commercial, open and neutral Logistics Centre.
Keywords: logistics centres, transport, terminal, development
The article deals with truck transport companies' development and problems in Latvia that have arisen after joining the European Union.
Keywords: truck, transport, company, European Union