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Abstract

The helical gears are widely used in different engineering applications especially in case of vehicles on the gear boxes. The aim of this research is the analysis of the effect of number of teeth on the pinion beside of the constancy number of teeth on the driven gear. Five types of helical gears have to be designed for the comparative analysis. Own-designed designing software are necessary for the facilitation of the designing and modelling process. During this research the normal stresses and normal deformations will be analysed into different directions by TCA method. After the analysis the functions of the mechanical properties and the number of teeth will be determined.

Abstract

The load factor is the determining factor for airlines in economic terms and the prediction of the future development of the flight route. The combination of load factor and break-even point provides the airline with a comprehensive picture of the business of the flight route and the optimization of pricing for the flight route. The purpose of the article is to propose and adapt the development of air transport prices on a given line using maximally recalculated values and maximize profit. The optimized calculation algorithm then facilitates the understanding of the individual steps of the load factor calculation and the monitoring of price development by means of the chi-square mathematical method by which we observed the interconnection of the ticket price and the load factor. To describe the problem, we chose the Bratislava – Larnaca route.

Abstract

The paper analyzes the costs of production of wood sawdust briquettes, manufactured by the company Brykiet-Pol2, based in Goleszów in southern Poland. In addition, production technology, raw material supply and distribution of the finished product were analyzed. The costs of producing one ton of briquettes for the four assessed variants ranged from PLN 364.8 (option D) to PLN 648.7 (option A). The cost structure was dominated by the purchase of raw material and depreciation of the technological line. The most economically advantageous production variant was option C, currently implemented in the company (production costs: PLN 458.7·t−1), and the proposed option D, using two briquetting presses. The latter option increased production efficiency and reduced unit costs of briquette production in a three-shift system around the clock.

Abstract

One of the important factors on which road safety depends is adequate visibility. This article analyses horizontal visibility within road intersections. The visibility condition depends on many factors, primarily on the geometric parameters of road elements and the location of buildings, fences, vegetation etc., neighboring the road. The aim of the research presented in the study was to determine the current condition of horizontal visibility, on the example of twenty two intersections located mostly in built-up rural area along a provincial road near Czestochowa. The research was carried out by two methods (the analysis of satellite photographs and the visual method) and the obtained results were compared. The assessment of the security level was based on applicable regulations and technical guidelines. It was found that the results of the visibility assessment based only on the analysis of maps and satellite photographs are in many cases overestimated, due to the fact that many small elements not visible in the photographs are not taken into account and the occurrence of convex vertical road arches within the field of visibility. However, the main reason for the insufficient visibility at the many intersections is the fact that the geometrical parameters of roads and their surroundings were shaped in the past when the traffic conditions were completely different. It was also noted that road managers perceive this problem and take measures to increase safety within road intersections.

Abstract

The article presents an analysis of the energy, mechanical and chemical properties of pellets made of wood material. According to the manufacturer, wood pellets were made of hard wood shredded to fractions approx. 1 mm thick and up to 3-4 mm long, and of a waste source - sawdust. Measurements of the selected properties were carried out on pellets with a diameter of 6 and 8 mm. Mechanical durability, humidity, crumble rate, ash quantity, calorific value were determined, as well as macronutrient and heavy metals content. The calorific value of pellets, with moisture content from 7.48% to 6.76% and ash content from 0.31% to 0.55%, ranged from 17.71-19.18 MJ·kg−1, which testified to the beneficial energy use of the tested raw material. Based on the conducted research, it was found that the mechanical properties of pellets made of both sawdust and hard wood predispose them for use as boiler fuel. The tested materials met high quality standards for wood pellets used for non-industrial and industrial purposes.

Abstract

Field tests on the quality of shaking off redcurrant fruit Rosetta cultivar with a half-row trailer harvester “Marek” produced by Dom-Wid were carried out. The tests were performed at two average working speeds ῡ1 = 0.47 m·s−1; ῡ2 = 0.60 m·s−1 and two rotational speeds of a tractor n1 = 1500 rpm; n2 = 1900 rpm. The length and diameter of shoots of redcurrant, length of a bunch, number of fruits in a bunch and mass of fruit were measured. Weather conditions were presented: rain fall, air temperature and moisture. Analysis of results showed that the working speed and the rotational speed has a significant impact on the quality and amount of the yield. At the highest rotations, the harvesting quality of fruit by a harvester was the worst and was 77.15%.

Abstract

Designing and proper implementation of effective processes and providing the customer with high quality products undoubtedly determines the stable position on the market. The aim of the study was to analyse the cost and value of the technological process of doors in the context of creating added value and to identify unnecessary processes (not creating added value) in relation to which appropriate corrective actions could contribute to their elimination. Thanks to the application of remedial measures, consistent with the lean manufacturing concept, the study eliminated, among other things, operations related to unnecessary transport and storage of products, which resulted in both the reduction of time and costs of process implementation.

Abstract

The research material was prune plums (Prunus domestica L.), subjected to osmotic pre-treatment, with variable process time parameters and osmotic solution concentration. Plums thus fixed were frozen and stored for 6 months. At even (monthly) intervals, the product was defrosted by the vacuum-steam method, using the s-p-p chamber, until the thermocouple indicated a temperature of 4ºC in the sample’s thermal center. In order to study the kinetics of phenomena occurring during the defrosting process, the chamber was equipped with a measuring system to enable measurement and recording of temperature changes in time in the geometric center of the sample, as well as the temperature on the sample surface. The conducted tests proved that the time of vacuum-steam defrosting of fruit depended on the amount of water contained in it. In plums dehydrated in 45-65% sucrose solutions, duration of the defrosting process was shortened already after three months of frozen storage. After 6 months of storage, defrosting of these fruits was twice as fast as that of control samples.

Abstract

The mining industry in Serbia has an important place in the country's economic development. Bearing in mind that the number of injuries that occur in the mining industry is unacceptably high, occupational safety and health is a challenge that existing and future mines will have to deal with. Studying injuries in mining, it was noticed that injuries requiring an absence from work for more than three days (especially fatal ones) are diametrically different in relation to the cause and manner of events related to injuries for which an absence from work is not necessary. In this research, authors focused on injuries that were characterized as ones requiring an absence from work. The statistical analysis of work-related injuries in mining is presented, as well as analysis of the direct causes of injuries, which are described as unsafe conduct of employees, unsafe conduct of company's management and/or unsafe working environment. In relation to classification of causes of injuries, a recommendation on what needs to be changed in order to remedy this situation in Serbia is given.

Abstract

The operation of various types of machinery and equipment constituting a material work environment exposes employees to many different hazards (especially mechanical hazards). According to the Polish law, the basic duty of both machine manufacturers and employers is to limit the level of these hazards and to provide employees with broadly understood safety. The article presents the basic issues related to the technical safety of laser cutter operators on the example of a selected industrial plant. Technical and organizational solutions used to reduce the level of risk associated with the use of the selected machine were assessed.