Silicon dynamics in the Oder estuary, Baltic Sea

Studies on dissolved silicate (DSi) and biogenic silica (BSi) dynamics were carried out in the Oder estuary, Baltic Sea in 2000–2005. The Oder estuary proved to be an important component of the Oder River–Baltic Sea continuum where very intensive seasonal DSi uptake during spring and autumn, but also BSi regeneration during summer take place. Owing to the regeneration process annual DSi patterns in the river and the estuary distinctly differed; the annual patterns of DSi in the estuary showed two maxima and two minima in contrast to one maximum- and one minimum-pattern in the Oder River. DSi concentrations in the river and in the estuary were highest in winter (200–250 μmol dm^− 3) and lowest (often less than 1 μmol dm^− 3) in spring, concomitant with diatom growth; such low values are known to be limiting for new diatom growth. Secondary DSi summer peaks at the estuary exit exceeded 100 μmol dm^− 3, and these maxima were followed by autumn minima coinciding with the autumn diatom bloom. Seasonal peaks in BSi concentrations (ca. 100 μmol dm^− 3) occurred during the spring diatom bloom in the Oder River. Mass balance calculations of DSi and BSi showed that DSi + BSi import to the estuary over a two year period was 103.2 kt and that can be compared with the DSi export of 98.5 kt. The difference between these numbers gives room for ca. 2.5 kt BSi to be annually exported to the Baltic Sea. Sediment cores studies point to BSi annual accumulation on the level of 2.5 kt BSi. BSi import to the estuary is on the level of ca. 10.5 kt, thus ca. 5 kt of BSi is annually converted into the DSi, increasing the pool of DSi that leaves the system. BSi concentrations being ca. 2 times higher at the estuary entrance than at its exit remain in a good agreement with the DSi and BSi budgeting presented in the paper.     

Application of the reverse 3D scanning method to evaluate the wear of forging tools divided on two selected areas

This study is focused on tools used in the industrial hot forging process of a front wheel forging (eventually–gear wheel) manufactured for the automotive industry. Four different variants were applied for the tools: 2 die inserts were coated with two different hybrid layers (GN + PVD type), i.e. AlCrTiN and AlCrTiSiN, one insert was only nitrided, and one was pad welded, to improve tool durability. The tool wear was analysed and represented by the material degradation on the working surface, based on the 3D scanning and the material growth of the periodically collected forgings. Additionally, the scanned tools were divided into two areas, in which it was found, based on the reliminary analysis, that various degradation mechanisms are predominant. Microstructural and hardness measurements of the analyzed tools were also performed. Based on the results, it was found that, in the central part of the die insert (area A), thermo-mechanical fatigue and wear occurred, while in the area of the bridge insert (area B), only abrasive wear could be observed. For these areas (A and B), the loss of material was determined separately. In area A for the inserts with hybrid layer GN+AlCrTiSiN and gas nitrided, an intensive increase of wear took place, which was not observed for the pad welded and GN+AlCrTiN layer insert, for which, together with the increase of the forging number, a proportional growth of the loss of material occurred. In area B the weakest results were obtained for the insert with GN+AlCrTiSiN layer, while wear of other die inserts grew similar and proportional.     

Multi-objective topology and size optimization of high-speed vehicle-passenger catamaran structure by genetic algorithm

Ship structural design has become recently an ever more important and difficult task, because it should always take into account several estimation criteria which are a crucial element of shipyard management, as the hull structural strength is one of the most important factors of overall ship safety, and the total cost of structural materials used for the construction of a ship is a significant part of her total construction cost. Simultaneously, a complete definition of the optimal structural design requires a formulation of size-topology-shape-material optimization task unifying the optimization problems from these four areas and giving an effective solution of this problem. So far, a significant progress towards a solution of this problem has not been achieved. An objective of the underlying paper was to develop an evolutionary algorithm for multi-objective optimization of both topology and scantlings of structural elements of large spatial sections of ships. In the paper an evolutionary algorithm where selection takes place based on the scalar objective function is proposed and applied to solve the problem of structural elements weight and cleaned and painted surface area on a high-speed vehicle-passenger catamaran structure with several design variables, such as plate thickness, scantlings of longitudinal stiffeners and transverse frames, and spacing between longitudinal and transversal members. The results of numerical experiments with the use of the developed algorithm are presented. They show that the proposed genetic algorithm can be an efficient multi-objective optimization tool for simultaneous design of the topology and sizing of ship structures.     

What Happened to the National Road Carrier in a Post‐Communist Country? The Case of Poland's State Road Transport

Abstract

The purpose of this article is to seek to reconstruct the ownership transformation involving Poland's State Road Transport (PKS) companies passed through after 1990. Data collected from various sources (above all the Internet) were used to establish the degree of advancement of the transformation processes. Despite the passage of 18 years since the new economic reforms were launched, privatization processes are not well advanced. State ownership remains dominant, in the form of Treasury companies as well as state‐owned enterprises. Privatization processes have encompassed fewer than half of all firms, the most popular form taken (in about a quarter of all analysed cases) involving leasing by workers. This would seem of major interest, attesting as it does to the greater activity of some worker's teams, as well as the passive role of the state in privatization processes. A much smaller number of firms (26) have been purchased by external investors, the only important international concern among these being Veolia, which had taken control of 11 PKS companies as of mid‐2006. By and large, it is the firms carrying passengers or passenger and goods that are in a much better situation, as opposed to the companies that are commodity‐carriers only. The majority of the latter have collapsed, or have undergone the kind of privatization that involves simultaneous shutdown. Mixed passenger and goods carriers have had to reduce their level of activity in commodity transport.     

Organizational and Ownership Transformation in Poland’s Urban Transport Companies

Abstract

This paper seeks to reconstruct the organizational and ownership transformation involving Poland’s urban transport that companies passed through after 1990. Data collected from various sources (above all the Internet, including the Bulletins of Public Information) were used to establish the degree of advancement of the transformation processes. Despite the passage of nearly two decades since the new economic reforms were launched, the privatization processes involving enterprises of municipal origin are not well‐advanced. There is not a single private company among the organizers of urban transport. Instead, an absolute domination of budgetary‐sphere entities may be noted. Furthermore, there are seven transport municipal unions. Among the operators (carriers) public ownership remains dominant in the form of single‐person local authority companies, local government companies, municipal union ownerships, municipal companies as well as budgetary units. Privatization processes have encompassed fewer than 10% of all operators in the form of companies with foreign participation, workers’ companies and companies with Polish non‐public sector participation. Moreover, in 20 localities urban transport is supplied by multi‐trade municipal services enterprises (as of end‐2008). Thus, transformation processes, though started earlier than in the case of Poland’s State Road Transport coach companies, are much less advanced.     

Numerical analysis of unconventional forging process of hollowed shaft from Ti-6Al-4V alloy

This paper presents theoretical analysis of unconventional forging process of hollowed shaft from Ti-6Al-4V alloy in a three-slide forging press. This method in comparison with other metal forming methods allows for obtaining of hollowed products. The designed process is verified theoretically by means of numerical simulations based on finite element method with assumption of 3D state of strain. The following factors are considered in the analysis: material flow kinematics, strain distribution, temperature distribution and force of process. On the basis of results, it is stated that the application of designed technology allows for obtaining of a product of assumed quality. A comparison is made between material consumption in analyzed process and material consumption in typical metal forming methods, also in used at present technology of shaft manufacturing by machining only. It is stated that the application of forging in the three-slide forging press allows for a considerable decrease of manufacturing costs due to material savings and decrease of labor consumption of operations at finishing.     

Budget calculations of nitrogen, phosphorus and BOD5 passing through the Oder estuary

The Oder River estuary is a large and complex system composed of lagoons, lakes and river branches in which numerous biogeochemical processes lead to modification of loads of dissolved/suspended material brought in with the riverine waters. Budget calculations show that on an annual basis, 71–88% of total nitrogen, 73–89% of total phosphorus and 72–101% of BOD₅ inflowing to the estuary are exported to the Baltic Sea. Among the inorganic nutrient species, nitrates exhibit the highest net transformation rate into organically bound forms (over 60%). The transformation could have been equally high or even higher in the case of ammonia and phosphates but these processes may have been compensated by intensive mineralization. The mechanisms responsible for the nutrient transformation patterns, as well as their net effect on the annual loads delivered into the Baltic Sea, are discussed in the paper. Phosphorus seemed to play a limiting role in phytoplankton production in the estuary in spring, while nitrogen did the same in summer.     

Book Review

This paper examines the relationship between investment in transportation infrastructure capital and the debt-to-gross domestic product (GDP) ratio. We analyse the effect of bringing forward investment originally planned for future years to be executed during times of economic crisis and also consider the possible advantages of carrying out such investments with private sector financing. This paper presents a model which shows how policy aimed to encourage investment in transportation infrastructure projects through private sector participation may help raise long-term GDP and thus lead to a lower debt-to-GDP ratio. The theoretical model is then applied to current empirical data from Israel.     

A data-driven approach for origin–destination matrix construction from cellular network signalling data: a case study of Lyon region (France)

Transportation - Spatiotemporal data, and more specifically origin–destination matrices, are critical inputs to mobility studies for transportation planning and urban management purposes....     

Deregulation in Polish Rail Transport

Abstract

A phenomenon new to the Polish situation—the deregulation of rail transport—is presented. Despite its primarily legal nature, deregulation also implies various economic, socio‐political and spatial consequences. The relatively short period over which partial deregulation of public transport in Poland has been in effect (i.e. since 2000) ensures that the issue has not been taken up by Polish geographers as a research field. However, it has been of interest to Polish economists. Deregulation is a phenomenon of primary importance, with direct implications for the character, quality, type, intensity and spatial differentiation of transport (including freight and passenger traffic) within the market economy. This paper, therefore, presents the impact of the recent changes in the legal system (as regards deregulation) on the current pattern of railway connections of the major carriers. As the majority of these originate beyond the Polskie Koleje Państwowe (Polish State Railways) Group, they can be said to be independent of the main former state carrier.