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Janez Usenik, Milan Batista
1997 (Vol 9), Issue 5-6
The article deals with bumper-to-bumper driving. A .systemicapproach to car-following (bumper-to-bumper driving)i.s described and the mathematical model has been developedand solved. With this approach an algorithm for analytical andnumerical solutions has been developed.

Peter Kochel
1997 (Vol 9), Issue 5-6
To allocate a fleet of vehicles to a given number of locationsand to redistribute free vehicles are important control problems.In this paper we use the results for multi-location inventorymodels to develop an approximate solution for the combinedfleet sizing and redistribution problem. For a defined rewardstructure we investigate:a) some properties of the optimal redistribution and allocationdecision respectively;b) the concavity of the expected one-period reward;c) the advantages gained from co-operation of locations overindependent locations.Since a model with discrete time is used, the proposed solutionis an approximation. The two-location model is investigatedin more detail.

Sanja Steiner, Borivoj Galović, Adolf Malić
1997 (Vol 9), Issue 5-6
Ecological indications and the depletion of fossil fuel resourcesare the main reasons for current studies of alternativepropulsion in aviation i.e. for searching for new regenerativeenergy sources. The technical and technological presumptionsfor the transfer from the conventional to alternative fuel aremore radical than the transition from piston to jet propulsion.The main problems include the production of liquefied hydrogen,the necessary aircraft structure modifications, and the requiredinfrastntcture supporl.

Teodor Perić, Nada Štrumberger, Gordana Štefančić
1997 (Vol 9), Issue 5-6
The quantification and types of costs in the river/touristtransport can be approached from different viewpoints.In river transport, the respective division into individualgroups or types, as compared to the total costs appears to be ofinterest.Apparent is the interdependence of individual costs and thelevel of utilisation of ship capacities (during a pleasure voyage).The basic costs of transport in river (liner) shipping are,thus, the costs of ship 's liner voyage, at average utilisation of thecapacities corresponding to the long-term anticipated demandfor ship space and specified profit, as well as the costs of capital.In the system of tourist/river transport. the costs involve:- total fued costs,- total variable costs, and-total voyage costs.All these groups include their sub-types in relation to shipvoyage, in quality and quantity terms.

Vladimir Brlić, Vlasta Žurić-Hudel
1997 (Vol 9), Issue 5-6
A multinational Project Trans Europe Lines (TEL) is ofgreat importance for the present development as well as for thefuture role and situation of telecommunications in the cowl·tries of Central and Eastern Europe (CEE). The idea of the necessityof constructing a fibre optic (FO) telecommunicationb1idge between Eastem and Westem Europe was initiated bythe Deutsche Bundespost Telekom and presented to some ofthe telecommunication administrations in that region in theyear 1990. The basic aim of the Project is to enable all countliesto improve and satisfY the telecommunication needs on internationaland national levels, to ensure sufficient transmissiontelecommunication infrastrncture in intemational traffic, toenable establishing of intense economic interrelations, to providethe basis for the development of future telecommunicationservices, and to support complete economic development in theCEE region.After its initialisation, the TEL Project was graduallyjoined by new Members and by the end of 1996 it included 16countries. Since initialisation until the end of 1996 TEL almosttripled in size regarding the physical area covered, and it becametwice as big regarding the involved number of inhabitants(potential subscribers).VarimLSt reasons were the 'driving force' for the numerouscountries insufficiently developed in the field of telecommunicationsand involved in the Project (as, for example, for the Republicof Croatia, in which TEL strongly supported its telecommunicationsdevelopment in spite of the difficulties of the warperiod 1991-1995 in the country).Thanks to the FO cable transmission systems which havebeen or are still being built within the framework of the TELProject and which represent the infrastntcture for the true CEEinformation highway, in the field of telecommunications, theProject M embers are not only connected among themselves butalso with the whole world, since the direct access points to TELare at locations of numerous 'landing points' of the intemationalFO submarine cables.

Mladen Nikšić, Veselko Protega, Dragan Peraković
1997 (Vol 9), Issue 5-6
The paper analyses the up-to-date research in developingmagnetically levitated (MAGLEV) motorcars. It presents thehistorical overview of the development of the most famousmagnetic levitation systems of today.Apart from describing the operation method and the technicalfeatures of each system, the paper ana(vses the advantagesand drawbacks of certain systems, as well as the advantagesand drawbacks of magnetically levitated motorcars comparedto conventional railway.The paper presents the plans for the future as well as the systemswhich have the highest prospects of being also commerciallyand not just experimentally used.

Slavko Šarić, Dragan Peraković, Gordan Brdar
1997 (Vol 9), Issue 5-6
ADSL (Asymmetric Digital Subscriber Line) is a technologythat allows transmission at 8.488 Mbps over the existingtelephone copper line (speed range depending on the distance).ADSL circuit connects the ADSL modems by twisted-pairtelephone lines creating three infonnation channels: high speedsimplex (maximum 9 Mbps), medium speed duplex channel(maximum 2 Mbps) and plain old telephone service channel.ADSL technology supports up to seven synchronous channelsthat can be configured to meet the needs of the end user.One could simultaneously view four movies stored in MPEG 1fonnat on separate television sets (MPEG 1 transmitted at 1.5Mbps), hold a video-conference (transmitted at 348 kbps),download data files from a server at 128 kbps via ISDN andeven receive a telephone call.

Hrvoje Baričević
1997 (Vol 9), Issue 5-6
The fleet of cars as one of the factors in the technologicalprocesses in transport has to be dimensioned in the optimalway. Market requirements are continually subject to changes,hence the demand for transportation services has to be modelledby means of quantitative methods. A mathematical modelfor determining the optimum size of the motor pool finds in thepaper its hypothetical presentation.

Igor Trupac
1997 (Vol 9), Issue 5-6
The paper deals with strategic goals and decisions to betaken for the integration of Slovenia into the European Union.One of the most important factors of this integration is transportation.This process should not be chaotic or driven by blindforces but carefully and strategically orientated in the macroand the micro field.The paper also suggests general strategy of transportation,defines goals, measures to be taken and identifies authorities.

Marijan Bolarić
1997 (Vol 9), Issue 5-6
1991 was the first year of operation of the Croatian Postand Telecommunications (HPT) in the independent state ofCroatia.The public corporation HPT- Croatian Post and Telecommunicationswas established by a resolution brought by theCroatian Parliament followed by a decree pronouncing the Acton founding of the public Croatian postal and telecommunicationcorporation.This survey has studied, analysed and evaluated the internationalexchange of Croatian Letter mail with the rest of theworld from 1991-1996.

Dušan Rudić
1997 (Vol 9), Issue 5-6
Continual growth of world maritime trade involves thegrowth of world shipping-industry capacities. This growth impliesnot only bigger ships and greater overall capacities, butalso some technical and technological changes that includenew ships, specialisation and development of new technologieswithin the maritime traffic.Due to complex navigation conditions, newer and more expensiveships that represent very complex and sensitive objects,the competition and human factor, the safety problem has oftenbeen out of control.The governments of countries within /MO and ILO increasinglyintroduce new rules and conventions to enhancenavigation safety. However, in view of economic-financial effects,many shipping companies overlook the safety problem.The most recent revision of STCW Convention and theISM Code implementation, which are becoming operative inthe current years, aim to increase the overall culture of qualitymanagement (QM) and to enhance the safety management onships and in maritime companies.

Eugen Varga
1997 (Vol 9), Issue 5-6
Over three million wooden sleepers are built into the Croatianrailway tracks. The durability of these sleepers depends verymuch on the fastening between the sleepers and the rails providedby the sleeper screws. The author suggests various systemsfor the fastening of the sleepers and the rails, especial~v in caseof the old ones, and particularly using the plastic replacingdowels.

Darko Dvornik
1997 (Vol 9), Issue 5-6
The paper examines the effects of implementing the panEuropeanmobile cell system -GSM (Global System for MobileCommunications) in the total tourist trade of the Republic ofCroatia, the procedure of its planning and integration in Croatia's telecommunication network and the influence on theEuropean and world-wide developments in trade and tourism.Special emphasis is laid upon the accessibility and range ofmobile se1vices that result from adequate network planningand the control of network traffic flow.The essential factors that influence service quality from theuser standpoint are identified.

Janez Usenik, Željko Radačić, Jasna Jurum-Kipke
1997 (Vol 9), Issue 4
The article presents a systemic approach to air traffic op·eration and control in which the airport represents a basictechnical-technological and organisational system. Determiningoptimum control of the airport system therefore representsthe most important component in the process of controlling airtraffic system.

Jasna Golubić
1997 (Vol 9), Issue 4
The railway has advantages over other branches of longdistancetransportation from the ecological, economic, safety,and technological point of view.The paper gives an evaluation of the favourable influenceof railway traffic on the environment reflected in the rationalenergy consumption, significantly reduced need of physicalspace, and reduced air pollution.Having these data in mind, the railway is considered tohave a negligible influence on environmental pollution. However,studying even such small amounts plays a significant rolein the traffic safety and in the lives of people and nature itself

Livij Jakomin, Igor Trupac
1997 (Vol 9), Issue 4
Today the modern production includes the following principles:liT (Just-in-Time), FMS (Flexible Manufacturing System),EOS (Economies of Scope), R&D (Research and Development),and increasingly present Lean Production.This article ana(vses how the mentioned principles, characteristicfor the production sphere, get integrated in the field oftraffic.

Slavko Šarić, Miroslav Mikula, Mladen Begović
1997 (Vol 9), Issue 4
The introduction of intelligence into the telecommunicationnetwork of Croatia is becoming one of the key elements ofthe future development of the network. The paper describes there-organisation of the telecommunication network in Croatia,the process of creating and managing the intelligent services,the initial situation and the feasible plan of introducing the INconcepts. The paper is concluded with a list of IN services thatare being introduced in the initial phase of the Croatian telecommunicationnetwork.

Teodor Perić, Nada Štrumberger
1997 (Vol 9), Issue 4
Considering the fact that noise is mostly caused by the trafficflow with all its characteristics, and in the production systemby machines, devices, and tools, it is necessary to implementmeasures for its prevention.Noise has to be eliminated on humanitarian grounds, andthen also with the aim of greater productivity and efficiency.However, regardless of the fact that, according to the analyses,by reducing noise the efficiency is increased and the costs(both fued and variable) reduced, these should not be the onlyreasons for its elimination; it should also be in the function ofthe organisation of the work place. Led by a human, ratherthan economic tendency, full satisfaction, good health, andmost of all increase in the productivity will be achieved throughsafety and protection.

Silvestar Perše, Dražen Kovačević, Branko Maković
1997 (Vol 9), Issue 4
The paper analyses some fractures of vehicle componentswhich have caused traffic accidents. The methods of analysingthe cause of fracture have been described, as well as the maintypes of fractures. The first analysed cause of a fracture is the excessivelyrough machine finish which leaves cracks (stress concentrators),the starting points of crack propagation. The secondcause is unprofessionally per[01med welding which later inservice causes fracture at the weld. The third cause is the toohigh content of carbon in the material of the railway vehiclewheel rim. Dwing braking, the higher content of carbon causedformation of excessively hard (and brittle) martensite in thesurface layer of the rim.

Eduard Missoni, Tomislav Mlinarić, Ivo Mlinarić
1997 (Vol 9), Issue 4
More than 500 million bicycles have been estimated to participatenowadays in the modem road transport. Bicycles arethe most numerous vehicles in the underdeveloped countries,whereas in the developed countries they are more frequent(vused for recreation and sport. Sudden revival of bicycle transportin modem times is like(v to continue, at a higher or lowerrate depending on the particular conditions in a certain country.The reason for this lies in the fact that bicycle is popular inunderdeveloped countries because of its low cost, and in the developedcountries it is preferred to motor vehicles because of itsecological, sport, and medical and recreational aspect.The present slow development of cycling in Croatia, is theresult of the war and post-war events, but this is expected tochange towards rapid growth in free Croatia. This should beour tendency out of the same reasons which hold for the developedcountries with special emphasis on tourism and environmentalprotection. Therefore, schoolchildren should be acquaintedat schools with all the advantages of riding bicycles,they should learn how to ride a bike and all about the trafficrules. For normal bicycle traffic, an appropriate bicycle lanenetwork should be constructed as soon as possible, for urbanand suburban traffic, as well as bicycle lanes for recreationaland tourist purposes. Moreover, the conditions should be createdand cycling promoted with the sport and racing spirit, inwhich Croatia has always had a great and brilliant tradition.

Livij Jakomin, Ivan Smerdu
1997 (Vol 9), Issue 3
Providing services on a quality level is an important factorof management in the trade rivalry for the control over the market.The factors affecting quality comprise technical factors andoperational and organisational ones. The technical factors includethe choice, the due care and maintenance of the vehicle.The operational and organisational factors are the quality offer,performing the transport service, the response in case of action,and the information efficiency.The necessity to control the total quality management is theresponsibility of the management. All staff members must participatein the improvement of quality management in their particularworking environment. Improved quality managementprovides for a higher safety of business operation and jobs, resultingin enhanced social security, which is gaining importancein mutual relations.

Blaž Bogović, Tomislav Mlinarić
1997 (Vol 9), Issue 3
The paper considers the environment and the tasks that theCroatian railways need to carry out in order to gain importancewithin the European transport market. It deals with the economicvalues that may be expected from the modernised railways.Therefore, the Croatian railways will have to undergotechnical, technological and organisational restructuring. Themarketing concept of meeting the customers' needs and demandshas to be developed. The marketing is meant and,among other things, the selection and definition of those segmentsin which the Croatian railways could do business successfully.These include: passenger traffic - suburban, then interurban(domestic and international in and out) and, accordingto the needs of the European railways, transit traffic. Ingoods transport - to identify the needs of big users and define thesize of the offer accordingly.Although the paper could not deal with concrete restructuringtasks (which is the first and foremost task of the CroatianRailways), it indicates the main directions. These include redefiningof the local traffic on railway lines class I!, then the employees,reorganisation and all the other transformations whichwill be carried out in continuity.

Ivan Dadić, Goran Kos
1997 (Vol 9), Issue 3
The paper deals with the implementation of Internet in trafficengineering with the purpose of improving the professionaland scientific research development of the traffic system in theRepublic of Croatia.Fast growth of the world computer network, Internet, andits applications in almost all the fields of human activities,change the picture of the modern world. The current exchangeof data in all their forms and the daily growth of the network,supplemented by almost incredible amounts of data that can bealmost instantly accessible, indicates that Internet is not just theinfomwtion technology revolution, but that it is a revolutionper se. More than 100 million computers are estimated to benetworked beginning of the 21' century.Internet seems almost as if it were created for the purposesof knowledge and expe1ience exchange in traffic, a relativelyyoung scientific branch. 11 can be concluded that the presenceof traffic engineers in Internet is today's reality and tomon·ow'snecessity.

Damir Šimulčik, Marinko Jurčević
1997 (Vol 9), Issue 3
The absence of a long-term traffic policy and of the policyof financing the constntction and maintenance of traffic infrastructurefacilities, represents a synthesis of numerous unresolvedrelations whose negative effects are felt in the overalleconomic and traffic development and consequently theevaluation of national potentials in the field. Adverse aspectcaused by the lack of a clear and feasible policy of financing thetraffic infrastructure facilities, is also a result of not having definedan adequate traffic policy, programme and strategiccourses of development, nor financing models that would be inaccordance with the market and economy system.This indicates that it is necessary to determine a policy forfinancing the constntction and maintenance of traffic infrastntcture,which has to be based on scientific development,team work, availability of plans and programmes to scientistsand experts, determined methodology based on marketing andeconomic logic in defining the programme and strategic tasksand assignments so as to make them feasible.In the near future, intensive preparations for investments inthe overall traffic sysiem are necessary, especially regarding thetraffic infrastntcture facilities - the pivotal points in the processof evaluating the traffic in our national tenitory. Croatia needsto define clearly its strategy in constructing and maintaining thegeneral traffic infrastructure, appointing at the same time thosewho will carry out the given tasks.

Adolf Malić, Zoran Stiperski, Dražen Kovačević
1997 (Vol 9), Issue 3
The authors analyse the reasons for using the interurban bustransport in Croatia based on a swvey carried out in 1996, on asample of 2,293 passengers. The respondents gave reasons fortaking the intentrban bus. The results indicate that the mainreason for taking the bus are going to or returning from work.Other reasons included going to school, visiting relatives andadministrative obligations at the local district.

Slobodan Beroš, Saša Mladenović, Špiro Matošin
1997 (Vol 9), Issue 3
The paper presents the research of the sophisticated vehiclerecognition and count system based on the application of theneural network. The basic elements of neural network andadaptive logic network for object recognition are discussed. Theadaptive logic network solution ability based on simple digitalcircuits as crucial in real-time applications is pointed out. Thesimulation based on the use of reduced high level noise pictureand a tree 2. 7. software have shown excellent results. The consideredand simulated adaptive neural network based systemwith its good recognition and convergence is a useful real-timesolution for vehicle recognition and count in the floating bridgesevere conditions.

Teodor Perić, Ivica Jurić, Savo Vojnović
1997 (Vol 9), Issue 3
The main task of this work is that of applying somespecific statistical and mathematical methods in researchingthe measures of concentration of the numberof employees and their net wages, in other words the incomesin certain economic branches of production andthe service sector in the Republic of Croatia.We deal here with the measures of inequality andevenness, and these are the Lorenz curve and the index ofconcentration. For the purpose of this research, 13branches, both from production and from the servicesectors, have been chosen for examining the measures ofconcentration according to the indicators.Before concrete realisation and calculation of thesemeasures of concentration can take place, a preliminaryvery delicate sorting out and modelling of the relevant parametershad to be carried out. This refers especially toadequate compounding of the carriers of the researchedphenomena.

Borivoj Galović, Berislav Grozdanić, Sanja Steiner
1997 (Vol 9), Issue 1-2
With the growing air traffic intensity, at some ai1ports weare more often faced with the fact that aircraft land or take offone after another. Since evety aircraft leaves a turbulent vortexbehind, which acts unexpectedly and is destabilising for theaircraft flying into it, the flight safety in such repeated landingsand takeoffs becomes questionable. Determining the minimumsafety time interval between the repeated operations becomesimperative and a limiting factor for some airports withhigh air traffic intensity. Unlike militaty flying, where crew istrained to fly in a group, in civil air traffic the crew is nottrained for such flying and on top of it mostly operate on largeaircraft, which produce very strong turbulent vortex. Additionalsophisticated equipment in new modem aircraft improvesnavigation, communication and steering of the aircraft, butdoes not insure it from flying into an invisible turbulent vortex.This paper discusses the vortex generation, its nature and fa ctorsthat influence its intensity and duration. The paper alsodeals with a model of calculating the probability of flying intoa turbulent vortex regarding time intetval of repeated opera tions,and influence of sophisticated equipment installed, onthe stability and flight safety of an aircraft. Conclusion underlinesthe need to standardise the minimum safety time intervalseparation between the repeated operations, with the aim ofimproving flight safety.

Ivan Bošnjak, Ivo Županović, Vesna Cerovac
1997 (Vol 9), Issue 1-2
Traffic science cannot emerge from 'emb1yonic state' if ithasn't common methodology and unified (fonnal) treatmentof traffic, relevant for different transportation and (tele)communicationsubsystems. Generalised model (metamodel) oftraffic process or traffic (system) the01y, must ensure consistencyand provide common platj01ms for large scale of trafficengineering (technologies) problems.This paper is concentrated only to consider dynamic approachin unified formal (mathematical) description of trafficprocess. Identification of some generic traffic relations andisom01phy are associated with the relevant contributions from'classical' traffte flow theory and teletraffic references. Dynamicflow models are considered as an approximation ofqueuing models and as an independent detenninistic and stochasticdescription of traffic process. Fwther 'more-integrated'contributions and development of generalised traffic (system)the01y are suggested.

Zoran Kožuh, Slobodan Kralj, Želimir Cvirin
1997 (Vol 9), Issue 1-2
The paper deals with some advantages and disadvantagesof adhesive bonding compared to concurrent bonding technologies,as well as possibilities of applying adhesive bonding injoining of materials. The listed joining methods are comparedto adhesive bonding, and the evaluation cliteria for each processare given.Some examples are presented regarding adhesive bondingapplication in automotive, aerospace and electrical industries.

Ernest Bazijanac, Ivan Mavrin, Silvestar Perše
1997 (Vol 9), Issue 1-2
The work analyses the possibility to diagnose the overalloperation of the piston engine based on the crankshaft angularspeed. The testing was camed out on the basis of the mathematicalmodel-simulator of malfunctioning. The possibilityfor diagnostics based on the lack of uniformity of the crankshaftspeed has been confirmed and the continuation of experimentingin practice with the proposed method justified.

Ivan Mavrić
1997 (Vol 9), Issue 1-2
The paper studies the problem of sequence optimisation inoverhaul activities production process modelling. Possibletasks, optimisation criteria and methods are analysed. Methodsfor solving two- or multi-phase production processes areillustrated on examples from practice. Special attention is paidto rules and criteria for selecting the optimal sequence in multi-phase production processes. For the given examples the optimalprocess sequence is presented graphically with the resultsanalysis.

Vesna Cerovac, Franko Rotim
1997 (Vol 9), Issue 1-2
The land and satellite communication systems provide amore rational utilisation of road network, by guiding the vehiclesto the destination using the best routes. This results in economicadvantages regarding reduced mileage, shorter travellingtimes, etc.

Gordana Štefančić
1997 (Vol 9), Issue 1-2
In order to establish the respective criteria for categorisationof bus stations, since no criteria have been determined yetbased on the world experience, the existing conditions havebeen analysed in all 64 bus stations in Croatia by use of questionnaires.Based upon the basic and additional facilities, busstations fall into four categories: A, B, C and D, and these arethen called basic and additional criteria.The basic criteria involve specific aspects obligatory forevery category. The number and type of aspects refer at thesame time to the minimum number of points assigned per category.There exists a 3-point discriminating difference betweenindividual categories.The additional criteria involve the accompanying aspectsrequired for the functioning of the system; they are optionalwithin the frame of a given number of points per category, andthere exists a 4-point dicriminating difference between individualcategories.Categorisation makes the basis for establishing the pricelist at bus stations, in turn imposing the requirement of provisionof a given level of bus stations services.

Nada Štrumberger
1997 (Vol 9), Issue 1-2
The article lists the unusual shipments in air transport.Over 2% of the annual cargo air transportation are the unusualshipments. Good co-ordination of the reception and deliveryprocesses of unusual shipments is one of the importantfactors in providing good and fast service knowing the basicregulations in air traffic.

Dražen Kovačević, Jasna Blašković, Branko Maković
1997 (Vol 9), Issue 1-2
Supply of goods, equipment and soldiers by militwy transportaircraft can serve as a support to airborne landing operation,support to encircled forces, and support to forces leadinga gue1rilla war. Transport aircraft are designed in such a wayas to be able to cany containers, pallets, most of land vehiclesand helicopters. Militwy transport aircraft can be grouped intothose that were originally designed for military transp01t andthose that are modified civilian aircraft and helicopters. Supplypallets can be wooden, metal, can be airdropped in 'taxiing','low-flight', and can also be fitted with a parachute or'retrorocket' for reducing the ground impact. Pallets canamong other things carry liquids, heavy combat and ca1rier vehicles,artillery and rocket weapons and valious containers.Pallets are usually pe1manently deformed at ground impact.Nowadays, high precision of airdrop has been achieved. Containersare used to carry various equipment, food, fue~ weapons,ammunition etc. It is to be expected that the containers,wmoured combat and other vehicles will be redesigned so asto provide more efficient transport and fast a!Tangement ofhigh-mobility units, whereas the form of the future militarytransport aircraft will not undergo substantial changes. By adjustingand standardising the transporlation vehicles, integraltransportation means and cwgo, the overall combat efficiencywill be increased, the a~rangement time especially shortenedand the air supply safety increased.

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