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Abstract

The paper discusses the possibility of using alternative fuels from bio-mass and plastics in Poland. Their physiochemical properties and possible application in the chemical, cement and energy industries were determined. The heat of combustion of the tested samples was 26.169 MJ·kg−1. On the other hand, the moisture content in the tested material was 1.6%, i.e. within the requirements for this raw material. Since the chlorine content in relation to the sulfur content in the waste is an indicator of the corrosive potential of the fuel, the content of chlorine and sulfur was determined in laboratory tests. The analyzed waste samples were within the specified requirements. The tested material, in which the chlorine content was determined (0.577%), indicates that the tested fuels can be included in the power industry, in accordance with PN-EN 15359:2012.

Abstract

A revalorised Burzyński’s hypothesis was suggested for determination of effort of construction elements in thermally variable load conditions. Using the suggested hypothesis, surfaces of the beginning of plasticity for the heat resistant St12T steel were determined. Two numerical simulations of thermo-mechanical loads of the turbine vane made of St12T steel were performed. The result of analyses was determination of the effort states of a vane acc. to Huber-Mises- Hencky’s hypotheis and according to the suggested revalorised Burzyński’s hypothesis.

Abstract

In the paper, the method of calculating the welding energy needed to regenerate parts of agricultural machines by welding (joining) or surfacing (rebuilding, hardfacing) is presented. Problems with the lack of adequacy of the commonly used formula for linear welding energy to the actual amount of heat introduced into the welded joint are discussed. A volumetric approach based on the effective amount of heat generated by the electric arc introduced per unit volume of the weld was proposed. The simplified formulas for volumetric energy are presented. The considerations are illustrated with examples of calculations. The analyzed examples include the use of a computerized stand for geometric measurements of metallographic specimens. The proposed volumetric method of calculating the amount of heat introduced into the welded joint is a more realistic indicator of heat demand than linear energy. On the other hand, based on the volume of the weld (padding weld), it allows to determine the amount of energy needed to regenerate machine parts, including agricultural ones.

Abstract

The article presents the results of tensile strength tests taking into account the influence of the printing nozzle diameter. The 3D printing method in FDM technology is described. The aim of the research was to investigate the effect of the printing nozzle diameter installed in the head. Samples printed with two types of filling were tested. The obtained results were summarized and compared. The printing time of the samples was compared with a diameter of each nozzle. Based on the strength tests, it can be concluded that the tensile strength of the samples made with the FDM printing technology is proportional to the used printing nozzle diameter.

Abstract

The article presents the methodology of testing sliding bearings with a flexible shell, focusing on the issue of temperature increase during experiments for a specific time interval of the START-STOP test cycle. Selected material pairs, used in previous studies, were used in the experiment. The stand used for tests in the start-stop cycle was developed under the project POIG.01.03.01-00-027 / 08-00 at the Faculty of Technical Sciences UWM in Olsztyn.

Abstract

The work presents a complex analysis and cost accounting of beet sugar cultivation in 2018/2019 campaign for individual farms of Lublin region. The economic results obtained by producers are mainly affected by indirect costs accounting for 60.11% of the revenue from the total production. Within this group of costs, the major components are sowing service, harvest and soil liming operations reaching 39.38%. Sugar beet production in the analyzed campaign was profitable, with the profitability index of 1.24 and unit production cost 14.33 PLN∙dt−1 is considered one of the profit-making activities in agricultural production, yet it is characterized by a high production cost that gobbled up to 80.39% of the total revenue in the analyzed 2018/19 campaign. The main factor influencing the income from sugar beet cultivation was the price for the raw material, which in the considered business year in relation to the previous season increased by only 0.77 PLN∙t−1.

Abstract

The paper discusses supplier evaluation as a tool for controlling the level of service in a production enterprise based on data from the selected production company. The suppliers were assessed and analyzed based on their respective assortment groups and strengths and weaknesses of their activity were indicated. It was found that the supply chain in the analyzed company is largely determined by the type of ordered goods, the place of its production and the method of its distribution to the customer.

Abstract

There are ca 1,492 thousand tractors currently used in Poland, with the average power of 45.3 kW. There are 9.8 ha of agricultural land per one tractor, their average age is ca 25 years and the degree of wear 77%. There are between 20 to 30 thousand tractors newly registered per year, however, these are both new and used tractors imported from abroad. These new registrations, which also reflect new purchases, are diverse depending on the region. Based on the 2018 records of the Central Register of Vehicles and Drivers (CEPiK), the paper establishes essential parameters of the registered tractors, such as price, power, age, depending on the region. There were 25,422 records under analysis, as some of the original records were dismissed as errors after verification. It was established that in the western part of Poland, with farms twice or three times bigger than in the rest of the country, the purchased tractors were characterized by higher power and lower age and, consequently, higher prices (81-95 kW, 14-18 years, PLN168-186 thousands). In contrast, the tractors in south-east Poland, where the dominant farms are of agricultural land below 10 ha, had worse parameters (76-86 kW, 14-18 years, PLN76-86 thousands).

Abstract

The article presents results of research on the bulk and shaken density of two commercial fertilizers: Pulgran urea and universal nitrogen fertilizer Salmag. A statistical analysis of the obtained results of average density at the assumed level of significance proved a significant difference between shaken and bulk density investigated with the use of Engelsmann apparatus and shaken density tested with a laboratory shaker for both investigated fertilizers. The obtained test results and uncertainty of the measured values served for calculation of uncertainty of the standard complex bulk and shaken density determined in case of many uncertainties. Further, an analysis of the impact of error sources on the value of complex uncertainty was conducted. The final results of the measurement were presented according to the convention of the Central Office of Measures.