The article discusses the basic issues related to the technology of friction stir welding (FSW). A short description of technology is provided. The following section provides the analysis of effect of technological parameters (tool rotation and welding speed) on the mechanical properties of the prepared joint (strength, ductility, microhardness). In both cases the analysis refers to aluminum alloys (6056 and AA2195-T0). The comparative analysis showed the phenomenon of the increase in weld strength along with the increase in the rotational speed of the tool during welding. Similarly, with the increase in welding speed, an increase in weld strength was observed. Some exceptions have been observed from the above relations, as described in the article. In addition, examples of material hardness distribution in the joint are presented, indicating their lack of symmetry, caused by the rotational movement of the tool. The analyses were performed basing on the literature data.
Volatility is one of the most characteristic features in the all market types. In the raw material market, including the bituminous coal market, volatility is visible in the supply and demand variations, in consequence in the prices fluctuations. Market actors usually having opposite interests, for example buy low, sell high, are vitally interested in identifying the causes of these fluctuations.
Some of the factors causing the market fluctuations are quite common, others are more complicated because of circumstances complexity. This article attempts to examine the relationships between bituminous coal fines prices and the economic situation. Given the complexity of the issue, the research area has been narrowed down – territorially to Poland and temporarily – to the present decade.
The average prices of coal fines in Poland are presented by the Industrial Development Agency (Agencję Rozwoju Przemysłu SA) in the form of two indices: PSCMI 1 and PSCMI 2. Both indices are calculated based on the prices of pattern bituminous coal, produced by domestic manufacturers and sold on domestic markets, the energy and heat market respectively.
Statistical methods, because of their quantitative nature, are important in identifying the correlations between the coal fines prices and economic conditions. Therefore, the article presents examples of relatively strong linear correlations between the PSCMI 1 and/or PSCMI 2 and some indicators of the economic situation.
In the text the author makes a critical assessment of legal solutions regulating the education of teachers in Poland. In the realms of argument, he refers to his own experiences as a member of the Polish Accreditation Committee. The presentation of those experiences reveals areas of omissions, irregularities, and even pathologies in the process of conferring teaching qualifications on graduates of schools of higher education. The author derives the sources of the status quo from imperfections or contradictions in the documents regulating the same areas of education, as well as from the struggle of schools of higher education to survive in the market, leading to a dramatic reduction in the quality of education. The text ends in demands for necessary modifications of the standards of teacher education and changes in legislation.
In the article the author acquaints the readers with a number of renovated nineteenth-century market halls, that are located in Barcelona, as well as the Markthal, a new and large market hall opened in Rotterdam in 2014. Avant-garde contemporary designs were presented, demonstrating the philosophy of introducing new shapes into a historical environment different for each architect. Apart from the predominant function of selling foodstuffs from practically all over the world, market halls are places, that are proof of the individuality and local traditions of every European city.
This article presents a quality analysis of convectively dried fruits and vegetables with preliminary osmotic dehydration. Tests were carried out on banana fruit and red beetroot samples. Hypertonic solutions of fructose for the banana and those of sucrose for the red beetroot were used, each one at three different concentrations. After osmotic dewatering treatment conducted at different time intervals and after osmotic dehydration the samples were dried convectively until an equilibrium with the surroundings was attained. Osmotic dehydration and convective drying curves were determined. The values of Solids Gain (SG), Water Loss (WL) and Weight Reduction (WR) were measured and changes in the samples’ colour and shape after convective drying with and without osmotic pretreatment were assessed.
The purpose of this paper is to reconstruct Roger Scruton’s views on patriotism and the attitudes of nationalism and oikophobia that endanger proper love of homeland. According to Scruton, patriotism is identical with loyalty to the people who inhabited a certain territory and share common culture, customs and history. The feeling of national loyalty so understood is peaceful by its nature and stabilizes the democratic system. Besides patriotism, Scruton distinguishes two attitudes, of worship of one’s nation and of hostility towards it. The first attitude may transform into nationalism, and then deifies nation and leads to wars and conflicts in history. Unlike the former, the attitude of hostility towards own nation (oikophobia) justifies development of transnational institutions that limited sovereignty of the democratic nation-states and – indirectly – undermine the sovereignty of one’s people. In the final part of the paper I paraphrase the concepts of nation presupposed in the attitudes of patriotism, nationalism and oikophobia, as they are discussed in the theoretical apparatus used by Leszek Nowak in his deformative conception of culture.
A data warehouse (DW) is a large centralized database that stores data integrated from multiple, usually heterogeneous external
data sources (EDSs). DW content is processed by so called On-Line Analytical Processing applications, that analyze business trends, discover anomalies and hidden dependencies between data. These applications are part of decision support systems. EDSs constantly change their content and often change their structures. These changes have to be propagated into a DW, causing its evolution. The propagation of content changes is implemented by means of materialized views. Whereas the propagation of structural changes is mainly based on temporal extensions and schema evolution, that limits the application of these techniques. Our approach to handling the evolution of a DW is based on schema and data versioning. This mechanism is the core of, so called, a multiversion data warehouse. A multiversion DW is composed of the set of its versions. A single DWversion is in turn composed of a schema version and the set of data described by this schema version. Every DW version stores a DW state which is valid within a certain time period. In this paper we present: (1) a formal model of a multiversion data warehouse, (2) the set of operators with their formal semantics that support a DW evolution, (3) the impact analysis of the operators on DW data and user analytical queries. The presented formal model was a basis for implementing a multiversion DW prototype system.
The article presents briefly several methods of working time estimation. However, three methods of task duration assessment have been selected to investigate working time in a real construction project using the data collected from observing workers laying terrazzo flooring in staircases. The first estimation has been done by calculating a normal and a triangular function. The next method, which is the focus of greatest attention here, is PERT. The article presents a way to standardize the results and the procedure algorithm allowing determination of the characteristic values for the method. Times to perform every singular component sub-task as well as the whole task have been defined for the collected data with the reliability level of 85%. The completion time of the same works has also been calculated with the use of the KNR. The obtained result is much higher than the actual time needed for execution of the task calculated with the use of the previous method. The authors argue that PERT is the best method of all three, because it takes into account the randomness of the entire task duration and it can be based on the actual execution time known from research.