Browse

31 - 40 of 143 items :

  • Business and Economics x
  • Materials Sciences, other x
Clear All
Experimental Verification of Method to Synthesize the Track Vertical Irregularities

Abstract

The paper focuses on the experimental verification of the results derived from numerical simulations, based on a model of the bogie-track system, where the vertical track irregularities are introduced in the form of a pseudorandom function. This function comes from an original method of synthesizing the vertical track irregularities, depending on the geometric quality of the track and on the velocity. To verify the method, the root mean square (RMS) of the simulated accelerations in the axles and the bogie frame against each axle is compared to the experimental accelerations within the frequency range of wavelengths of the track vertical irregularities from 3 to 120 m. The results have shown a good correlation between the simulated RMS accelerations for a low quality track and the measured RMS accelerations.

Open access
How can people be convinced to buy electric cars? – case of Slovenia

Abstract

Electric cars represent a promising energy-and carbon-efficient alternative to internal combustion engine cars. However, as mobility behaviour is highly habitual, convincing people to switch from conventional cars to electric is challenging. In the following research, which was carried out in the past years in Slovenia, an attempt was made to determine what influences people’s buying habits and what would motivate them to buy an electric car. It appeared that the most relevant factor for not purchasing electric cars is, firstly, its overall too high price, and, secondly, short driving ranges. Different studies, as well as the results of the following research have revealed that there is no single measure which would dramatically increase the demand for electric cars. The solution is to combine different measures or strategies like Top – Down and Bottom – Up, where both the government and car industry should come across.

Open access
Innovative Calculation Method of the Productivity of Vibrating Screens Used in Mineral Aggregates Sorting

Abstract

In the process of preparing cement or asphalt concrete – frequently used in ways, roads and access road construction, it is necessary to sort out poly-dispersed granular mixtures from bilge deposits or quarries. The mechanical sieving performs the separation of the granules on dimensional sorts (the size of graded grains can be 1... 70 mm) by means of machines called screeners. In the case of vibrating screeners, the working body (the sieve) presents a vibratory movement that ensures a high productivity of the screening machine and a very good quality of the final products obtained. The article studies the productivity of the vibrating screen used in mineral aggregates sorting process obtained by different methods. In this regard, a pragmatic simplified formula called Pragma is proposed, a formula which was tested with good results in situ experiments done on a bi-mass vibrating screen in a pilot station.

Open access
Keeping Higher Education Aligned with the Requirements and Expectations of the Knowledge-Based Economy

Abstract

Paper describes the procedure for developing academic programs which are properly aligned to the requirements of the knowledge-based economy. The paper also addresses the continuous quality improvement (CQI) process with the CQI loop closing on the program level and the course level. This process is needed to make continuous adjustments to an academic program, so that the program is always aligned to the constantly-changing needs of the economy. Paper also discusses the system of mutual dependency between the academic program and external partnership like local industry, secondary schools, local government, local community, regional business incubator center, other educational institutions, alumni and industrial advisory council. The ongoing collaboration with external partners allows the program to prosper and grow.

Open access
LEAN Production issues in the organization of the company - the first stage

Abstract

Today’s market determinants and most importantly, very dynamically changing customer requirements significantly shortened the product life cycle. This situation reflects in companies by common extension of the assortment offered and personalised serial production. The result of a flexible approach to market changes is the implementation of LEAN concept, which, both in terms of management and production aims to develop efficiency within an organisation, which will then enable quick and dynamic response to changes in the environment. The popularity of LEAN concept (in management and production) among managers comes from its universality and a wide range of instruments used to maximise the use of existing potential. The main assumptions of LEAN concept are aimed at the maximum use of an organisation’s resources, defining the activities necessary to execute an order and identifying the areas generating losses and then minimising them and eventually eliminating. LEAN concept is based on flagship-main tools for identification and modernisation of processes, the difficulty in using them results from the need to recognise and select the most effective ones that meet the expectations of a given organisation. The article presents issues related to the first stage of implementing LEAN concept in a company’s structures, i.e. identification of opportunities and selection of appropriate tools.

Open access
Modal Competition and Complementarity: Cost Optimization at End-User Level

Abstract

The paper aims to identify possible methods for balancing the allocation of transport flow on modal subsystems in order to efficiently use the infrastructures and reduce the negative effects of today’s unbalance. The aspects of intermodal competition are reviewed, considering the economic concepts regarding the substitutability of transportation services, conformation degree to the perfect competition model and the nature of cross elasticity demand.

A top-down analysis over the whole infrastructure assembly is performed. The results, under the presumption of valid work hypothesis, indicated that for further analysis the set of networks transferring material flows can be assumed as disconnected from the other networks sets transferring energy, informational and values flows.

The second part of the paper develops, for that disconnected networks, a generalized cost optimization model for multimodal transportation, where the comfort and safety are accounted. Thus, the performance of the existing algorithms based only on trip length, trip duration and energy consumption can be significantly improved. Additionally, the author proposes three new independent types of modal analysis that allow end-users and companies involved in transport organization to optimize their modal choice and the whole transport process organization.

Open access
Preliminary Studies to Use Textile Fibers Obtained from Recycled Tires to Reinforce Asphalt Mixtures

Abstract

The use of crumb rubber in the modification of asphalt has occurred because of the problems related to disposal of scrap tires. However, the use of scrap tires in asphalt pavements, known as asphalt rubber pavements, can minimize environmental impacts and maximize conservation of natural resources. The textile fibers from recycled tires are typically disposed of in landfills or used in energetic valorization, but similar to other fibers, they can be used as a valuable resource in the reinforcement of engineering materials such as asphalt mixtures. Thus, this work aims at studying the use of textile fibers recycled from ground tires in the reinforcement of conventional asphalt mixtures. The application of textile fibers from ground tires was evaluated through laboratory tests on specimens extracted from slabs produced in the laboratory. Indirect tensile tests were performed on a series of nine asphalt mixtures with different fiber and asphalt contents and compared with a conventional mixture. The results obtained from a 50/70 pen asphalt were used to define three asphalt mixture configurations to be used with 35/50 pen asphalt. The results indicate that the textile fibers recycled from used tires can be a valuable resource in the reinforcement of asphalt mixtures.

Open access
Problems of Polish enterprises in the field of innovation

Abstract

Innovative activity of enterprises in Poland is mostly generated by European funds that concern boosting European regions based on its significant resources and new technologies. Polish enterprises development within innovations is based mainly on accumulating new products and new technologies that improve organization and increase sale of products and services. Papers presents research findings that concern problems resulting from the innovations implementing in Polish enterprises comparing with European results. There is presented European Innovation Index providing a comparative assessment of the innovation performance at the country level of the EU Member States and the Regional Innovation Scoreboard (RIS) that presents results of innovative activity in Polish and European enterprises including regional data from the Community Innovation Survey (CIS).

Open access
Review of Policies for Promotion of Electric Vehicles

Abstract

This paper presents the review of policies and their possible effects for promoting the use of electric vehicles. Suggestions on faster implementation of electric vehicles can also be identified within best practices from abroad. Various countries have adopted different policies to promote the use of electric vehicles which include fiscal or other forms of incentives that would persuade people into buying electric vehicles. Possible effects are hard to determine since many variables affect a consumer’s purchasing decisions. That is why identification of policies that have proven to be successful and those that have not achieved projected results and should be improved is necessary. Research has shown that countries with most promising policies for promotion have the biggest share of electric vehicles and invest the most in their promotion (fiscal incentives).

Open access
Simultaneous Influence of the Track Axis Curvature and the Support Line Obliquity at Railway Bridge Superstructures with Steel Beams Embedded in Concrete

Abstract

For new railway bridges with small spans (L ≤ 35.00 m) superstructures with steel beams embedded in concrete are recommended and used, which can ensure the requirements of strength and especially stiffness, regardless of velocity.

In all the design prescriptions used so far for superstructures with steel beams embedded in concrete, and even in the technical literature, there is little information and data on the influence of the support line obliquity and the track axis curvature in the design and calculation of these types of structures.

In the design code, if certain conditions related to the geometry of the superstructure are met (obliquity, curvature) the calculation is a simplified one, made on a single isolated longitudinal beam of the deck; otherwise, if the conditions are not met, finite element program analysis is recommended.

The article aims to study the situations in which the requirements of the design prescriptions are not met.

Open access