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The logistical support necessary for the organization of type tests of rail vehicles is a complex task. Resources that must be provided are expensive and related to the complex organization of work in the field. On the other hand, the relevant European standards are technically more and more demanding, so the logistical support is also more extensive. In this paper, the focus is on the presentation of activities related to type tests of freight wagons. The testing of the brake system is shown in detail. For this test it is necessary to perform measurements on an open track, at different running speeds and different levels of vehicle loading. Given that the test is performed by decoupling the wagon, it is necessary to apply a number of technical measures that will ensure that the test is performed safely and with minimal risks. By applying the network planning method, it was shown that although there is a relatively small number of activities, each of them can be critical, i.e. in case of delay may cause additional costs, that can be identified during planning, but which are not recognized and most often not acknowledged by the purchaser of the testing.

For many years, methods for assessment the safety against derailment of railway vehicles have been developed and improved. Possible approaches to solve this task are conducting real in-situ measurements or the application of MBS simulations. The goal of both approaches is to reliably determine the lateral Y and vertical Q forces and their Y/Q ratio. The limit values of this ratio, which should not be exceeded, are defined by standards and in technical reports of the European Technical Committees. Based on the complex geometry of the wheel-rail contact and other parameters of the vehicle and the track, this should ensure that derailment will not occur. In the experimental approach or measurement of relevant parameters, in Europe there are several methods defined by the standard EN 14363. All of them are extremely complex and demanding in terms of conditions to be provided and logistics, so in recent times tendencies are to apply simulations. This paper presents the results of the derailment safety tests of several types of freight wagons using method 2 of EN 14363. The application of this method was made possible by the development of an original wayside system for measuring the wheel-rail contact forces and the development of a hydraulic test rig for twisting a complete wagon. The results of these tests show that some freight wagons, although with standard running gears and standard dimensions, have quite high ratio Y/Q forces during curve negotiation.

Draw-buff gear plays a significant role in the transmission and damping of longitudinal forces generated during accelerating and braking of trains. The role of the buffers is to protect the railway vehicles bearing structure, cargo and passengers from excessive longitudinal impacts. Especially when shunting freight wagons. For that reason, they have built-in elastic-damping elements that absorb shocks and partially convert kinetic energy into heat. This paper analyzes buffers with rubber-metal springs, which are the most often used in the freight cars nowadays. The static and dynamic force-stroke characteristics obtained by measurements on hydraulic press and during buffing impact tests are presented. These results are then compared with calculations using FEM analyses. The analyses included checking of the buffers ability to absorb a sufficient amount of energy that can be generated during wagon normal operation and in the case of exceptional shunting impacts.

The increased capacity of freight railway traffic leads to increased noise pollution. The existing regulation TSI NOI defines the maximum noise level allowed to be emitted by railway vehicles. Consequently, the noise tests are mandatory type tests for all new vehicles. Experience from noise tests of different freight wagons have shown that measured noise level depends on many parameters and in most cases is close to the maximum permissible values. Contemporary design of the freight wagons has to be conceived such as to emit as low noise as possible. Accordingly, it is necessary to identify the main influencing sources that affect the noise generation and to find a way to reduce their influence. This paper presents results obtained by measurements of pass-by noise of a freight wagon, with wheels having different wheel tread surface roughness. It appeared that wheel-rail rolling contact as a noise source is very significant and may be critical for assessment of the railbound vehicles.

Wheels for rail vehicles are made according to precisely defined geometry and dimensions. The wear of the wheel profile in operation is not uniform, so the initial profile changes. It is a consequence of the inevitable slippage, which is influenced by a large number of factors. Certain changes in the profile can be important for the safety of movement and riding quality, so the shape of the profile in operation must be regularly checked through characteristic dimensions measurements: the flange thickness, the flange width and its slope. Changing the characteristic measures can lead to: thinning of the flange over the allowed limit, which can lead to its cracking, increase in the height of the flange, which can cause problems with derailment at crossings and switches, reducing the slope of the flange, which can lead to derailment on the switch tongue. The paper presents the verification of the dimensions and shape of the pattern for control wheel profile for the type of tread shape S1002, which are used to control the wheel profile after reprofiling. The dimensions of the S1002 wheel profile are given in EN 13715 on the basis of which the control patterns are made. After making the pattern or the control accessories, its dimensions were checked by scanning on a 3D scanner Atos core 200. The resolution of the scanner is 0.08 mm, and its working surface is 200 x 150 mm. The 3D model was obtained by scanning, from which the coordinates of the scanned profile were obtained with the help of the GOM Inspect software package. Based on these coordinates, a comparison was made and a deviation from the nominal profile.

From the aspect of safety, brakes of rail vehicles are an extremely important system on the vehicle. Braking performance affects the normal functioning of vehicles and interoperability of rail vehicles in classic railway train compositions. All trains, classic and different type of motor trains must conform with the available stopping distances, which are predefined by the railway signalling, i.e. control length of a signal and depends on the maximum allowable speed for which the track section is designed. Apart from that, in classic wagons, which are combined and participate in the formation of different train compositions, mutual compatibility must be ensured from the aspect of used braking equipment and connection subassemblies, but even more important, braking performance of all wagons in the train has to be uniform within certain tolerances. This prevents weaker braked wagons from running into stronger braked ones, which can cause longitudinal jerks and may in extremes lead to a train rupture. Stopping distance during brake application depends on train braking performances, longitudinal running resistance and presence of wind and its direction. This paper deals with the influence of wind conditions on the results of slip brake tests and the estimation of a single vehicle's braking performance. Based on experimental measurements, simulations using CFD and comparison with the obtained results, this paper proposes a possibility to extract air drag resistance and wind force from the total resistance force. Presented methodology and obtained results may serve for further simulations of aerodynamic characteristics apart from braking performance, such as vehicle running resistance, energy consumption, etc. and for optimization of the wagon shape and design.

Предмет изучавања докторске дисертације су симплицијални комплекси при- дружени алгебарским објектима као што су циклотомични полиноми и иредуцибилни карактери решивих група. Приликом анализе придружених комплекса посебан нагласак је на некомутативности структура које се испитују. Алгебарском објекту као што је циклотомични полином може се придружити колек- ција симплицијалних комплекса. Хомотопски тип придружених симплицијалних ком- плекса у већини случајева даје потпуну информацију о коефицијентима циклотомичног полинома. Једини изузетак су циклотомични полиноми чији је степен једнак производу три различита проста броја и овај случај је у фокусу истраживања у овој докторској ди- сертацији. Хомотопски тип симплицијалног комплекса придруженог полиному Φpqr(x), где су p, q и r различити прости бројеви, одређује се помоћу дискретне теорије Морса, када је то могуће. Међутим, у посебним случајевима симплицијални комплекси придру- жени полиному Φpqr(x) имају некомутативну фундаменталну групу, чиме је обезбеђена нова некомутативна инваријанта оваквог типа полинома. Сложене презентације које се појављују као презентације фундаменталних група придружених симплицијалних ком- плекса анализирају се коришћењем Фоксовог рачуна. Други тип придруживања који се разматра јесте придруживање симплицијалног комплекса скупу иредуцибилних карактера коначне решиве групе. Придруживање се врши на два начина, као комплекс заједничког делиоца и комплекс простих делитеља. Проучавање фундаменталне групе оваквих типова симплицијалних комплекса обезбе- ђује боље разумевање структуре скупа иредуцибилних карактера коначних решивих група., This dissertation examines simplicial complexes associated with cyclotomic polynomials and irreducible characters of finite solvable groups. In the process of analysis of the associated objects special attention is paid to the noncommutativity of the examined structures. A collection of simplicial complexes can be associated to an algebraic object such as a cyclotomic polynomial. In most cases, the homotopy type of associated simplicial complexes gives us complete information about the coefficients of the cyclotomic polynomial. The only exceptions are cyclotomic polynomials whose degree is a product of three different prime numbers and this case is the focus of research in this doctoral dissertation. When it is possible, the homotopy type of a simplicial complex associated with the polynomial Φpqr(x), where p, q and r are different prime numbers, is determined by using the discrete Morse theory. However, in special cases, the simplicial complexes associated with the polynomial Φpqr(x) have a noncommutative fundamental group, thus providing a new noncommutative invariant of this type of polynomial. Complex presentations that appear as presentations of the fundamental groups of associated simplicial complexes are analyzed using Fox’s calculus. This thesis also focus on the study of simplicial complexes associated to a set of irreducible characters of a finite solvable group. Two types of simplicial complexes are attached to a set of irreducible characters of a finite solvable group — character degree complex and prime divisor complex. The examination of the fundamental group of these types of simplicial complexes provides better understanding of the structure of the irreducible characters of finite solvable groups.

Let R be an associative unital ring and not necessarily commutative. We analyzes conditions under which every n×n matrix A over R is expressible as a sum A = E1 + ... +Es +N of (commuting) idempotent matrices Ei and a nilpotent matrix N.

Railway vehicle “Avenio” is a Siemens low-floor tram model. One of the steps towards the successful production of this tram is reflected in the optimal production of each sub-assemblies and element. The most important aspect of the development and production of elements is the safe operation of the vehicle system and comfort drive during exploitation. In addition, it is necessary to take into account the cost-effectiveness of its manufacture as well as maintenance costs. In order to reduce the production and maintenance costs of the whole system, the production of one of the components of this tram that is called a “tilt stabilizer” was optimized. This element has a very important role within the vehicle construction because it controls the inclination of the vehicle body in relation to the bogie around the longitudinal axis. This way reduces the discomfort to passengers caused by centrifugal force and prevents further narrowing of the vehicle profile. The primary design of this assembly is based on the welded construction. The device consists of 4 mechanical elements built into the tram structure. Bearing in mind that welded construction characterizes a higher cost of production, the idea was to design subassembly for the production on a numerically controlled machine and to successfully replace the current method of production in this way. For the newly adopted solution of the model, a static strength calculation was made which determined that the tested model satisfies the load conditions that occur in the structure. Static strength analysis was performed by finite element method in the "Ansys Workbench" software package, according to the criterion for equivalent "von - Mises" stresses. Results showed that modified structure and applying of new production method give absolutely acceptable assembly with requested strength and significantly lower life cycle costs.