Simplified calculation methods of internal combustion engine screw joints are presented, with respect to screw fastenings of connecting rod bearing; crankshaft main bearing and fuel pump camshaft bearing. Design criteria for proper bolt dimensioning and tightening force estimate as conditions for screw joint safety are discussed.
Among all engine auxiliary units a cooling fan is the noisiest. There are two mechanisms that generate the overall noise of the fan: the rotational and non-rotational one. These mechanisms depend on the fans geometry and operation conditions. The rotational noise is characterized by a broadband noise and superimposed discrete frequency tones. The superimposed tones are linked with the blade passage frequency and its higher harmonics. In heavily loaded conditions (at the lower flow rate) non-rotational noise is found to be prevailing. The non-rotational noise spectrum has a peak at frequency that is not related to the rotational speed or blade passage frequency. Rotational noise is mainly the consequence of the fluctuating forces on the rotor blades and is provoked by the interaction of the rotor blades with the nearby stationary objects. Non-rotational noise is caused by: a) laminar boundary layer vortex shedding, b) blade interaction with the tip clearance vortex and c) blade stall. The goal of this paper is highlight all these noise generating mechanisms caused by axial fans in IC engines cooling applications.
The paper deals with a review of importance of motor cars in the transport and economic system of Croatia with reference to the progressive nations. The review then covers the course of studies fora degree provided by the Department of Engines and Vehicles of the Zagreb University Faculty of Mechanical Engineering and Naval Architecture since the institution of the Engineering School in 1919 to the present. The paper presents the courses of graduate and postgraduate studies. A statistical review is provided of the number of students that have been conferred a Bachelor's, Master's or Doctor's degree in the field of transportation means.
The paper presents an analytical method for determining optimal number of servicer in a big repair workshop. This method is based on the theory of mass servicing (TMS). A short description of basic concept, principles and limitations of this theory is given. The adequate mathematical model is created on the concrete examples of the mass servicing system (MSS). On the basis of this mathematical model, the quantitative characteristics for all variants of MSS are defined and analyzed. Finally, the most important quantitative characteristics, basic parameters of the optimization goals and an optimal solution for analyzed variants are presented and discussed
The paper deals with the effects of electromagnetic fields upon participants in postal traffic (employees and users). The authors first provide a general review of the effects of electromagnetic fields upon people, and then a special reference is drawn to the examination of properties of non-ionizing electromagnetic fields (of particular intensity with postal radio relay facilities), possible harmful effects of subject fields upon people, and individual aspects of protection and their efficiency.
Traffic infrastructure makes an integral part of the traffic and economic system of each country. The designers of traffic infrastructure investment policy have to meet the requirement for this policy to be based on scientific developments and synchronized activity of all economic system segments. In the article the accent is assigned to the development and integration capability of traffic infrastructure facilities.
The Article offers a complete model for calculation of emission of harmful components from motor vehicles driven by Otto motor and supplied with three-way catalyst. The calculation model contains several parts. The starting base makes the determination of load of the motor, i.e. torque and speed in order to overcome the imposed resistance of driving. Then there follows a complete thermodynamic calculation process with the motor cylinder for the necessary load. Emission of harmful components at the motor outlet is calculated from the balance state of gas at the combustion end. Finally emission of harmful components after the three-way catalyst outlet taking into account its efficiency. Using this model calculation for vehicle VW Passat driven by Otto motor of volume 2000 cm2 with a three-way catalyst performed in the article. Working regimes are taken according to the vehicle cycle of the Europe-test.
The study of the behavior of different track panel structures on the lines of the Croatian Railways has been completed in regular conditions of utilization. The subject research has been conducted by measurement of strain in straight and curved track sections.
In order to have fluctuations in traffic reduced to the minimum and on to a predictable scale, the paper deals with the measuring and forecasting of passenger flows at bus stations. Particular attention has been fixed on traffic forecasting by the method of correlative analysis. The examination of respective indices, coefficient of correlation, and value trend have all comifired the adequacy of the Gompertz trend, being of particular importance for the projections of fixture demand for traffic services.
The paper deals with the study of problems appearing in the process of operation of the Diesel engine with different fuel mixtures. The results of the experiment run for the Diesel engine by application of D-method show the interdependent aspect of the working cycle factors and the ratio of gasoline in Diesel fuel.
The paper deals with the methodology for establishing the units of mechanized fleet for operation and handling in container terminals. Selection of the type and number of manipulation equipment is completed based upon the computation (estimate) taking account of the time needed for the completion of individual operation, and setting the time quota for loading and unloading. Also included in the computation is the capacity of reloading equipment from which we are able to work out the utilization-related i.e. actual capacity. By review of dimensions and capacities of container cranes and straddle carriers the methodology for selection of the needed fleet is completed.
By introducing and structuring the nation's independent military forces the Republic of Croatia has adopted the model of training of military pilots in the civil system of training at the University of Zagreb, following different educational models. Military pilot training models adopted in Air Forces of Western nations, are of a layered concept, with different levels of engagement and discharge of pilots, however the training structure is conditioned by accurately defined requirements i.e. especially in practical training being adopted in the model of training of the Croatian Air Force pilots. Generally speaking, practical training (qualifying for the completion of missions and licensing requirements) refers to basic, advanced and special training upon completion of selection of prospective candidates. Basic pilot training means the actual acceptance of candidates into the profession. Therefore its role is of paramount importance in training. It consists of several stages or levels in the process of competent evaluation of flyer characteristics of future pilots. At the University of Zagreb and Military Academies in the Republic of Croatia there are available scientific potentials (both teaching and material) ensuring high-quality and high level of efficiency of militar) ·pilot training.
The study of combined modern transport technologies in the Danube-Adriatic region refers us to the conclusion of major significance of transport corridors and freight flows and relative lagging behind of surface transport as a whole. Particular reference has been drawn to the low level of development of transversal traffic routes crossing the territory of the Republic of Croatia on the route from the Danube Region to the Adriatic Region. Without constitution of modern railway lines and highways to be integrated into the European TER and TEM systems it shall not be possible to complete the traffic related evaluation or promote the Adriatic Orientation policy of the Republic of Croatia. The model of linkage and modernization of surface and sea transport involves the modernization of the overall technological and traffic infrastructure, and introduction of modern information system(s) to enable linkage of all participants in traffic on the Danube-Adriatic corridor.