Search Results

1 - 9 of 9 items

  • Author: Dariusz Kowalski x
Clear All Modify Search

Abstract

The paper deals with the method to identify internal stresses in two-dimensional steel members. Steel members were investigated in the delivery stage and after assembly, by means of electric-arc welding. In order to perform the member assessment two methods to identify the stress variation were applied. The first is a non-destructive measurement method employing local external magnetic field and to detecting the induced voltage, including Barkhausen noise The analysis of the latter allows to assess internal stresses in a surface layer of the material. The second method, essential in the paper, is a semi-trepanation Mathar method of tensometric strain variation measurement in the course of a controlled void-making in the material. Variation of internal stress distribution in the material led to the choice of welding technology to join. The assembly process altered the actual stresses and made up new stresses, triggering post-welding stresses as a response for the excessive stress variation.

Abstract

Subject and purpose of work: The subject of the article is an analysis of the state aid rules by state authorities in the context of calculating the amount of state aid. This problem was discussed on the basis of a relatively new form of assistance repayable instruments. The aim of this article is to identify the noncompliance of the rules generally applicable to the rules for repayable support. Materials and methods: In order to achieve the objectives set, the analysis of the identified problems was based on non-reactive research involving the assessment of available information. It included studies of normative acts, literature of the subject and reports and analyzes. Results: It has been identified that the current form of act on State aid cases does not take into account the specific nature of aid calculation under return instruments, which is that the final value of the state aid is known only after the repayment of the financial instrument. Conclusions: The legislator should adjust the law on proceedings in state aid cases, the more frequently used form of State intervention is repayable finance. The current practice differs from the literal wording of the provisions in question and should therefore be amended to adapt the provisions to this form of aid.

Abstract

Steel materials, due to their numerous advantages - high availability, easiness of processing and possibility of almost any shaping are commonly applied in construction for carrying out basic carrier systems and auxiliary structures. However, the major disadvantage of this material is its high corrosion susceptibility, which depends strictly on the local conditions of the facility and the applied type of corrosion protection system. The paper presents an analysis of life cycle costs of structures installed on bridges used in the road lane conditions. Three anti-corrosion protection systems were considered, analyzing their essential cost components. The possibility of reducing significantly the costs associated with anti-corrosion protection at the stage of steel barriers maintenance over a period of 30 years has been indicated. The possibility of using a new approach based on the life cycle cost estimation in the anti-corrosion protection of steel elements is presented. The relationship between the method of steel barrier protection, the scope of repair, renewal work and costs is shown. The article proposes an optimal solution which, while reducing the cost of maintenance of road infrastructure components in the area of corrosion protection, allows to maintain certain safety standards for steel barriers that are installed on the bridge.

Description of Pikeperch, Sander Lucioperca (L.), Semen Obtained from Males Held Under Different Rearing Conditions

The aim of the study was to determine the concentration and motility of sperm and the osmotic pressure and total protein in the seminal plasma of pikeperch, Sander lucioperca (L.). The samples investigated were milt from males held under various rearing conditions (ponds, tanks of a closed recirculating systems, cages). The highest percentage of motile sperm was noted in the semen samples from males held in basins, while the lowest percentage of motile sperm and the highest protein content was confirmed in the samples from spawners held in ponds. Sperm motility and the osmolality of the seminal plasma were low in all the spawner groups; this may indicate contamination with urine. As the content of protein rose in the plasma and the sperm concentration increased, so did their motility.

Abstract

The article presents the possibilities of advance development of detailed organization-technical plans for the repair of Highway Strips, which will enable their effective use, particularly during combat operations – while maintaining the required time and technical standards at the same time. The main objectives of Highway Strips were presented; their role in securing military aviation activities and historical conditions for their creation. The concept of HS (Highway Strip) was defined along with the modern principles for their construction, modernization and renovation. Based on a selected example, the principles for evaluating the technical condition of their pavement and the repair possibility assessment were presented. At the same time, typical damage to HSs and factors affecting such damage were presented. Next, the methods and technologies for repairing various types of bituminous pavement damage repairs were discussed, with particular emphasis on the methods of repairing cracks, surface damage, deep damage and asphalt renovation. A schedule for the “Wielbark” highway strip was also developed, and the necessary calculations of the repair times, as well as the resources and resources for securing these operations were made. The article is concluded with a short summary and a proposal for further work, aimed at inhibiting the destructive processes of Highway Strips in Poland.

Abstract

The research article discusses the advantages of using compressor downstream air partial bleed and supplying it downstream of the turbine, which was applied in a prototype of a “bypass” turbojet engine. The objective of such a turbo engine structural solution was discussed along with its elements and principle of operation. Further part of the article determines the impact of such partial air bleed on the value of achieved basic operating parameters of the engine, i.e., unit thrust and unit power consumption. The presented attempt to compare these parameters with the parameters achieved for a turbojet, single flow engine is very important; in the first case without air bleed, and in the second, with air bleed to the environment. Further sections of the article compared these parameters relative to a turbojet, turbofan engine with a jet mixer. Such comparisons enabled to determine the actual benefits of using compressor downstream air partial bleed and supplying it downstream of the turbine, which may constitute an intermediate solution between single flow turbine engines and turbo fan engines. Wide possibilities for the application of such structural solutions were shown, which was summarised in the conclusions.

Abstract

The article describes the problem of the operation of turbine jet, adaptive engine work on the natural environment. In particular, the analysis of noise generated by turbine jet engines has been made. It points out possible directions of noise decrease with particular emphasis upon structural changes within the engines, the task of which is to reduce the noise mission. The example of the modernization is based upon the “bypass” type of one-flow turbine jet engine. The essay contains theoretical basis of calculation of the noise emission level and the results, which graphically indicate a relative level of noise of this type of engine depending upon the amount of discharged air and the diameter of the discharge nozzle and the radius, upon the basis of which the noise level is determined. This work also includes a comparison of the relative noise level of this type of engine with regard to one-flow turbine engine equipped with the function of air discharge to the environment and with regard to two-flow turbine jet engine equipped with air stream flow mixing device. The use of low-emission combustion chambers in the “bypass” turbine engine was indicated. This allowed addressing the problem of emissions of toxic exhaust components by this type of aircraft engines. At the same time, the dependence of this emission related to the mass of fuel used on the engine's thrust range was indicated. The article was concluded with a short summary.

Influence of temperature on the effectiveness of the hormonal stimulation of male ide, Leuciscus idus (L.)

Increasing the temperature of water (by 1-2°C) in which spawners of rheophilous fish are held following hormonal stimulation until gametes are obtained is a common procedure in hatching practice. The aim of the study presented here is to determine the influence of water temperature following stimulation with Ovopel on the investigated quantitative and qualitative characteristics of ide, Leuciscus idus (L.), milt. The experiment comprised subjecting the fish to hormonal stimulation using a single intraperitoneal injection of Ovopel at a dose of 1 pellet kg-1 of body weight. After injection, the water temperature of group I was maintained at a constant level of 10°C, while for the other two groups it was increased to 12°C (group II) and 14°C (group III) within 4 hours. Changes of temperature after hormonal injection had no statistically significant effect either on milt quantity or its quality parameters. The values of motility were low in all groups (29, 30, 35% for groups I, II, and III, respectively). The mean values of seminal plasma osmotic pressure were 129, 139, and 154 mOsm kg-1 for groups I, II, and III, respectively. The mean values of spermatozoa concentration in the milt of the males held after hormonal stimulation in water at 10, 12, and 14°C were 10.68, 10.71, and 9.92 × 109 ml-1, respectively. Following the injections of Ovopel, total number of spermatozoa produced by the males (TSP, X 109) was the highest in the group held at 12°C (3.03 × 109); however, it was not statistically different from the other groups. No significant differences in either TSP or the number of spermatozoa per kg of their body weight (TNS, X 109 kg-1 b.w.) among the studied groups were noted (P > 0.05). In contrast to females, there is no need to change the water thermal conditions for ide males after hormonal stimulation.

Abstract

Water suppliers can be treated as production companies whose main product is water delivered to their customers. The article presents problems connected with management of such companies in the conditions of secondary contamination in water distribution systems. This phenomenon exists in water networks all over the world. Its’ presence is particularly visible in countries of former communistic block. In the article particular attention was devoted to the issue of water quality correction in the analysed systems. In the case of water distribution systems, former quality correction methods consisted in special treatment of water pumped into the system, flushing and cleaning of water pipes. In both these cases identification of water quality deficiencies resulted in significant water loss. The situation reflects management processes applied in the manufacturing industry of the 1940s. The authors of this paper put forward the concept of three water quality correction methods which would not entail such considerable water loss. The methods in question are intended for different network types. The implementation of proposed solutions could set new standards in management of distribution systems of water providers.