Evaluation of the strength anisotropy for railway wheels

The results of experimental investigation of railway wheel failures and strength anisotropy due to rolling contact fatigue are presented. The results indicate that plasticity acts to concentrate regions of intense hardening near the edges of contact. The determination of overall mechanical properties of small-scale volumes frequently relies on the indentation technique. Strength characteristics of the wheel material were investigated by dynamic indentation method and portable dynamic indentation tester was used for hardness measurements. It was found that some characteristic force values of the instrumented hardness test are very well correlated to tensile strengt

The possibility of increasing the quantity of oxygenate s in fuel blends with no diesel engine modifications

Two fuel kinds of organic origin including rapeseed methyl ester (RME) and ethanol (E) were selected for their different physical-chemical parameters to study the maximum apt volume of oxygenates to mix fossil diesel (D) and establish expectancy to apply D–RME–E blend as a fuel for the unmodified high–speed diesel engine (a combustion chamber consists of a dished piston). The objective of the article is to provide an explicit relationship between the nature of fuel composition and diesel engine operating parameters. The results of the carried out tests on the engine oriented on dynamic and emission characteristics using various portions of the before mentioned bio-components in diesel fuel are presented. Engine behaviour seemed to be improved in the presence of ethanol additives in D–RME blend with a reduction in pollutant emissions in exhaust gases, fuel consumption, ameliorated cetane number, ignition delay time and physical-chemical characteristics of the investigated compounds. The positive and negative aspects of applying bio-based additives in fossil diesel are reported and discussed. First published online: 24 Jun 201

The Implementation of Green Logistics in Road Transportation

The article presents an analysis of academic literature in an attempt to identify the importance of the implementation of green logistics in road transportation. Areas of concern as well as solution and implementation opportunities are presented. A research of transportation companies was conducted in an attempt to understand the real situation regarding the implementation of green logistics measures. The research results are presented in the article. Solutions are provided in the form of a conceptual model for the implementation of green logistics measures in transportation organisations. Nowadays the interest in ecology, minimization of fossil fuel usage, and mitigation of harmful road transportation consequences is rapidly increasing. Eco-friendly vehicles, effective transportation system, application of advanced technologies and innovations should become the main factors in promoting the implementation of green logistics in the transportation sector to mitigate negative effects on the environment. In order to maintain their competitive advantage and customer satisfaction, transportation organisations should begin implementing the concept of green logistics in their businesses. The significance of the concept of green logistics can be observed on global, regional, and national levels. Business is still seen as the leader, responsible for initiation and implementation of ecological logistics principles. The implementation of green logistics is critically important; however, lack of funding and collaboration between the public and the private sectors prevent companies from adopting green logistics measures. Economic driving classes, employee education, electric and hybrid cargo-handling vehicles are some of the possible green logistics measures

Theoretical aspects of logistics training process management

Authors discuss about main training needs and problems in the logistics as main driving motive for learning and training process organization in the universities and at the non‐formal training places ‐ work places, courses and training organizations. All driving motives can be named as internal and external forces which influence persons. In many cases external driving motives are related to person's “positive pushing” direction, for example, integration and globalization process in business or implementation of the new technologies. The internal driving motives sometimes are related to problematical points of training, i. e. negative self‐estimation, negative view of environment and bad understanding of knowledge's benefits in the person's practical life. The main problems and perspectives of logistics training process are named in this article. Main reasons for training process, methodology and training costs are described. First Published Online: 27 Oct 201

The restoration of physical and mechanical properties of wheel rim metal

Despite reduced resistance to wheel rim wear, after every grinding, only geometrical parameters of wheels are restored at maintenance depots. A tendency towards a decrease in the exploitation of wheel rim working edge induces the acquisition of new wheels, is related to a considerable increase in axle load and train speed as well as linked to the ineffective methods of repairing wheel rim working edge. A solution to the problem of restoring the surface of wheelset rolling, as a wider problem of rolling stock durability, is determined by the fact that the breakdown of the rolling wheelset and the loss of its efficiency shortens the service time of the wheelset. The cost of pointless and inefficient renovations of geometrical wheelset parameters increases and is of a very high rate. The problem of efficient renovations to rims and steel used for wheels within the maintenance of wheelsets becomes a burning issue today

The design and investigation of two storage/retrieval mechanisms of the cylindrical automated storage and retrieval system

The objective of this research is to propose and investigate a new design of the Cylindrical Automated Storage and Retrieval System (C-AS/RS) and provide a performance comparison of the two types of Storage/Retrieval Mechanisms (SRM I and SRM II) for the system configurations with different input/output location numbers and positions. Although the better performance is expected from of the system with SRM II, because it contains the vertically independent moving load handling devices (LHDs) compared to the interconnected LHDs used in SRM I, the vertically independent movement requires more sophisticated equipment which should be considered by the system designers. Hence, the performance investigation is required to identify the differences between the two types of the SRMs for different C-AS/RS configurations. For this purpose, the detailed simulation model of the C-AS/RS was developed, investigated for various combinations of system parameters and the multiple regression models for predicting system performance measures were developed (adjusted R-square greater than 0.83 for all models). The differences of the performance measures were evaluated and showed that SRM II achieved 7÷20% higher load retrieval rates compared to SRM I for all investigated parameter combinations. The investigation also showed that the number and position of the input/output locations had a significant impact on the system performance

Modelling and investigation of car collisions

While investigating collisions with immovable obstacles it is necessary to assess the place of contact, its character and the speed of vehicles before the contact. These parameters depend on the obstacle. The most common cases were analyzed in the article: collision with an immovable obstacle which deformed only a part of the fore of vehicle (collision with a tree, a bollard, etc.); collision with an immovable obstacle which deformed the whole fore of vehicle (collision with a wall, etc.). First Published Online: 27 Oct 201

Analyzing the aspects of organising paratransit services in Vilnius

The main objective of the paper is to analyze some aspects of organising new paratransit services in Vilnius. The main presented scientific problem is the creation of a new transportation system integrating it into the existing one. The system in Vilnius is not well adapted to people with disabilities, and therefore special transportation services for people having impaired physical mobility do not meet the requirements established for paratransit services. To solve this problem, an objective of researching demand for new services in Vilnius, the impact of such service for the whole transport system and potential problems that could arise during the organisation and installation of new services have been set. In order to create such system, one needs to know the values of specific parameters identified with the help of an expert survey. Scientific literature and information obtained from the expert survey allow making a conclusion that new paratransit services are required and can be integrated into the existing system in Vilnius

Principles for modelling technological processes investigation into the strength and durability of automatic coupler sa‐3 in railway carriages

The paper presents the durability analysis of the automatic coupler in railway carriages. The loading of the automatic coupler predetermined by the weight of a train, train speed and railway relief is a time‐dependent variable. The finite element method was used for stress‐strain state calculation taking into account acting forces. In order to reduce stress concentration, the geometry of the automatic coupler's body was modified. Modelling results for different rounded radii demonstrated it was possible to reduce stress concentration up to 34%. Under maximum forces, plastic strain occurs in the automatic coupler's body. The calculation of strain and stress state in the body of the automatic coupler shows it is under a static, low and high cycle loading. Therefore, to calculate the durability of the automatic coupler, the dependencies for low cycle nonstationary stress limited loading has been proposed evaluating low cycle quasistatic and fatigue damages. In order to evaluate high cycle fatigue damage, a linear law for the summation of loading cycles has been suggested. For low cycle damage evaluation, the calculation method for the summation of fatigue and quasi‐static damages created at one loading cycle taking into account loading level and neglecting the sequence of cycles has been put forward. Thus, to calculate the automatic coupler for each specific case, it is necessary to determine the number of loading cycles at each loading level and to evaluate durability considering dependencies presented in this paper. First published online: 27 Oct 201