Construction risk assessment is the final and decisive stage of risk analysis. When highly changeable conditions of works execution are predicted, risk should be evaluated in the favorable, moderate, and difficult random conditions of construction. Given the random conditions, the schedule and cost estimate of the construction are developed. Based on these values, the risk of final deadline delay and the risk of total cost increase of construction completion are calculated. Next, the charts of the risks are elaborated. Risk changes are shown in the charts and are analyzed in the range [1, 0].
The paper presents an analysis of the influence of elevated temperature on thin-walled purlins restrained by sheeting. In the first part of the study the bearing capacity of purlins cooperating with sheeting is examined in normal and elevated temperature based on European Standards. Next, special attention is paid to creating a numerical FEM model of the restrained purlins in Abaqus program taking into account different materials properties with respect to temperature increase.
Temporal differentiation of the air thermal conditions in SW part of Spitsbergen has been presented in this paper. Daily meteorological records of the Polish Polar Station of the Polish Academy of Sciences in Hornsund have been used for the period of 1978—1986. Distributions of basic thermal indices based on mean, maximum, minimum air temperatures and minimum temperature at a ground surface have been given. Annual patterns of the above elements of various occurrence probabilities have been also presented and thermal periods have been distinguished.
Multidisciplinary research was carried on in 1978/79 in the region of Admiralty Bay and Arctowski Station. This area is representative of the near-shore Antarctic ecosystem. It is characterized by a number of local traits such as climate, ice conditions, hydrology, hydrochemistry and hydrodynamics. Estimates were made of primary production and abundance of zooplankton in Admiralty Bay and of the biomass and quantity of food taken by avi-fauna and pinnipeds. Main routes and directions of transport of mineral and organic matter are shown; some of them have been estimated quantitatively. A continuous inflow of organic matter from Bransfield Strait is necessary for the summer functionning of Admiralty Bay.
The aim of this article is to defi ning problems occurring in the spatial management system, including those independent of subsequent legislative changes. The process of adopting decisions to be viable and socially equitable and execute the requirements of spatial order and sunstainable development requires fundamental changes. The study draws a conclusion – important in the context of subsequent research activities – that the varied application of development decisions in diff erent municipalities is also the result of not preparing a large part of the representatives of municipalities for specifi c spatial activities.
Ground temperature measurement results in main ecotopes of the Kaffiöyra coastal plain (Oscar II Land, northwestern Spitsbergen): sea beach, tundra and morainic plateau, are presented and discussed in the paper. The spatial distribution of thermal conditions is discussed with particular regard to temperature of the active surface and vertical gradients of temperature dependent on daytime and weather conditions.
An investigation of cyanobacterial microflora in the northern, deglaciated part of James Ross Island in the NW part of the Weddell Sea, Antarctica , was conducted during the Antarctic summer season 2005-2006. Five main types of habitats with dominant cyanobacterial assemblages were analyzed (soils, seepages, streams, wetted rocky walls and lakes), and main ecological variables were measured (pH, temperature, intensity of global radiation, conductivity and nutrients), as a background for further ecological and ecophysiological studies. The definable traditional cyanobacterial morphospecies were identified.
This paper describes the spatial differentiation of topoclimatic conditions in the vicinity of the Arctowski Station (King George Island, Antarctica) during the summer season of the 2006/2007. The measurement stations were located in the Point Thomas oasis as well as on the Ecology Glacier and Warszawa Icefield. The paper analyses meteorological elements such as air temperature, air humidity (eight sites) and wind direction and velocity (three sites). Significant topoclimatic diversities resulting from denivelation, exposure, ground properties and local air circulation were recorded in the study area.
Soil-plant conditions in selected valleys typical for Bellsund Region are varying from hardly favourable (Skilvika), to favourable (Calypsostranda) and medium (Lyellstranda). Plant growth and development of a soil cover are favoured by grain size composition (loamy sands and light loams), quick warming-up of a soil, relative stability of a ground, location and shape of valleys, etc. Unfavourable soil-plant conditions result from too light or too heavy grain size composition, considerable dynamics of ground mechanical features and high compactness of a soil. Varying contents of carbonates and alkaline reaction (except for almost neutral reaction in organic horizons) were typical for the studied soils. Thickness of humus horizons as well as contents of organic C vary at the three studied sites. Significant is high concentration of easily available Ca and Mg, sometimes also of Na.
With reference to the situation experienced in several Polish collieries where the risk of occurrence of gas-geodynamic phenomena is increasing and decisions to start the mining activities need to take numerous constraints associated with previous mining into account, this paper addresses certain geo-mechanical aspects of longwall mining in the zones of excavation edge interactions giving rise to major changes in the conditions of the deposit and rock strata, as a consequence of previous mining operations in adjacent coalbeds. Starting from the analytical description of displacements and stresses in the proximity of longwall mining systems, the paper summarizes the results of model tests and investiga-tions of the influence that the excavation edge has on the behavior and structural continuity of a portion of the coal body in the coalbed beneath or above an old excavation. Based on selected nonlinear functions emulating the presence of edges in the rock strata, a comparative study is carried out by investigating two opposite directions of workface advance, from the gob area towards the coal body and from the coal body towards the gobs. The discussion of the results relies on the analysis of roof deformation and the concentration factor of the vertical stress component at the workface front.
In the Accession Treaty of 16 April 2003, Poland agreed to adopt euro as its national currency, but the date of this adoption was not specified. The financial crisis in several countries of the Eurozone, in response to the world financial crisis in 2008, reduced drastically the public support in Poland for the replacement of the zloty by the euro. This article has two objectives. One is to assess the net costs, economic and political, for Poland remaining long outside the Eurozone. In this assessment the analysis includes also two official reports by National Bank of Poland, the country’s central bank, published in 2009 and 2014. The other objective is to note and assess the reforms which have been undertaken by member states of the Eurozone in response to this crisis, in order to maintain and enhance financial stability and economic effectiveness of the rules adopted at the start of the Eurozone on 1 January 1999. The author suggests to consider and adopt additional reforms. Discussed is also the USA experience with its own monetary union, and the potential influence on policy developments in the EU of increasing global competitive pressures from China and India.
The paper aimed to get the analysis of spatial horizontal distribution of summer phyto-plankton in a small and shallow lake (Głębokie, Western Polesie, CE Poland) in relation to wind conditions occurring during the research period. The study was conducted in 2011 from 5th of July to 5th of September with eight sampling dates between. Water was sampled in the littoral zone from the depth of 0.5 m in four sites situated in different and opposite to one another lake shores. We analyzed the phytoplankton abundance by the way of chlorophyll a determination as well as the community taxonomic structure. Our research revealed that: a) the direction of the wind, which occurred during sampling might have an important role in the horizontal distribution of planktonic algal biomass within the lake; b) the geomorphology of lake surroundings probably mitigated the influence of wind on phytoplankton distribution; c) even weak or mild wind may influence phytoplankton horizontal differentiation.
Mid-winter rapid rise of temperature in the vicinity of Arctowski Station, King George Island (West Antarctica) was studied in 1991. Depending on circumantarctic migration of cyclones, sudden drop in air pressure and foehn-like phenomenon intensified by local topography occurred. Two such events are described on May 13 and June 28, against meteorological conditions during autumn and winter. Extreme intensification of morphogenetic processes caused degradation of a snow cover, immense meltwater discharge, radical transformation of slopes, effective aeolian activity and dynamic modifications in a sea-shore zone.
Due to unfavorable factors, dangerous conditions occurred in the delivery of electric energy in Poland. This was the most serious incident of its kind since the 1980’s. Such a serious incident raised concern about the safety of the electric power system in the summer and led to the formulation of conclusions for the future. In this article, the author analyses the conditions, which caused that situation. Poland was experiencing a doubt in August 2015, which along with an extremely high maximum daily temperature created remarkably unfavorable conditions for power plants and decreased the capacity of overhead power lines. Such unfavorable metrological conditions occurred not only in Poland, but also in Central-Eastern and Western Europe. It is worth emphasizing that the safety of electric energy delivery was endangered only in Poland. The improper renovation and upkeep policies, as well as unplanned outages in power plants caused a significant decrease of available power in the National Electric Power System. Unscheduled flows between Germany and Poland ruled out the possibility of importing electric energy at such a critical time. The author presents the correlation between the maximum daily air temperature in the sweltering heat and an increase in the demand for electric energy. Overall, unfavorable conditions posed a threat in the delivery of electric energy in Poland. In this article, the author draws attention to the report from the Supreme Audit Office (Najwyższa Izba Kontroli – NIK) from 2014, which predicted such a dangerous situation. Unfortunately, that report remained unnoticed. The author formulated appropriate solutions in order to increase the safety of electric energy delivery in the summer and to prevent such occurrences in the future.
The paper presents the results of assessment studies of the time course for technical wear in masonry buildings located in the area of mining-induced ground deformations. By using fuzzy inference system (FIS) and the “if-then” rule, corresponding language labels describing actual damage recorded in structure components were translated into scalar outputs describing the degree of damage to the building. Adopting this approach made it possible to separate damage resulting from additional effects coming from mining-induced ground deformations and the natural wear and tear of masonry structure. By using statistical analysis an exponential function for the condition of building damage and the function of natural wear and tear were developed. Both phenomena were subject to studies as a function of time regarding the technical age of building structure. The results obtained were used to develop a model for the course of technical wear of traditionally constructed buildings used within mining areas. In the course of natural wear and tear buildings located in mining areas are additionally exposed to forced ground deformations. The increase of internal forces in structure components induced by those effects results in creating an additional stress factor and damage. The hairline cracks and cracks of building structure components take place when the intensity value of mining effects becomes higher than the component stress resistance and repeated effects result in the decrease of structure rigidity. The observations of building behaviour in mining areas show that the intensity of mining activity and the multiplicity of its effect play a substantial role in the course of technical wear of buildings. The studies show that the level of damage resulting from mining effects adds up to natural wear and tear of the building and impairs the global technical condition as compared to similar buildings used outside mining areas.
The debate between Ludwik Fleck (microbiologist and philosopher of science) and Tadeusz Bilikiewicz (historian and philosopher of medicine) took place shortly before the outbreak of World War II and remained virtually unnoticed until 1978. A wider recognition of their exchange was possible only after the English and German translations appeared. Basically, the polemics concerned understanding of the concept of style and influence that the environment exerted on scientific activity and its products. The polemic started with the review of Bilikiewicz’s book Die Embryologie im Zeitalter des Barock und des Rokoko (1932) where the historical account of the development of embryology in the early and late Baroque period was interwoven with bold sociological remarks. The commentators of the debate were quick to notice that the claims made by Fleck at that time were crucial for understanding of his position, especially because they let to interpret his views in a non-relativist way. While the importance of the controversy was univocally acknowledged, its assessment so far has been defective for two reasons. First, for decades the views of Bilikiewicz were known only from the short and rather critical presentation given by Fleck and this put their discussion into an inadequate perspective. Second, for over 40 years it remained a complete puzzle what prompted their exchange of views. This paper closes these gaps. Thus, on the one hand, I reconstruct the central issue of the disputation between Fleck and Bilikiewicz and situate it within the context of Bilikiewicz’s views. On the other hand – and this is more important – I try to explain the origin of their debate by quoting some recently discovered and unpublished archival materials. A review of their correspondence gives me an opportunity to advance some hypotheses about the aims and hopes connected with their project but also possible reasons for its failure.
The interesting properties of a class of expanding systems are discussed. The operation of the considered systems can be described as follows: the input signal is processed by a linear dynamic converter in subsequent time intervals, each of them is equal to Ti. Processing starts at the moments n · Ti, always after zeroing of converter initial conditions. For smooth input signals and a given transfer function of the converter one can suitably choose Ti and the gain coefficient in order to realize the postulated linear operations on input signals, which is quite different comparing it to the operation realized by the converter. The errors of postulated operations are mainly caused by non-smooth components of the input signal. The principles for choice of system parameters and rules for system optimization are presented in the paper. The referring examples are attached too.
In this paper a three-dimensional model for determination of a microreactor's length is presented and discussed. The reaction of thermocatalytic decomposition has been implemented on the base of experimental data. Simplified Reynolds-Maxwell formula for the slip velocity boundary condition has been analysed and validated. The influence of the Knudsen diffusion on the microreactor's performance has also been verified. It was revealed that with a given operating conditions and a given geometry of the microreactor, there is no need for application of slip boundary conditions and the Knudsen diffusion in further analysis. It has also been shown that the microreactor's length could be practically estimated using standard models.
Hornsund and Kongsfjorden are two similar-sized Arctic fjords on the West coast of Spitsbergen. They are influenced by cold coastal Arctic water (Hornsund) and warmer Atlantic water (Kongsfjorden). Environmental conditions affect the timing, quantity, spatial distribution (horizontal and vertical) of spring and summer blooms of protists as well as the taxonomic composition of those assemblages. Here, we compile published data and unpublished own measurement from the past two decades to compare the environmental factors and primary production in two fjord systems. Kongsfjorden is characterized by a deeper euphotic zone, higher biomass and greater proportion of autotrophic species. Hornsund seems to obtain more nutrients due to the extensive seabird colonies and exhibits higher turbidity compared to Kongsfjorden. The annual primary production in the analysed fjords ranges from 48 g C m-2 y-1 in Kongsfjorden to 216 g C m-2 y-1 in Hornsund, with a dominant component of microplankton (90%) followed by macrophytes and microphytobenthos.
The role of two submerged macrophyte species (Ceratophyllum demersum and Potamogeton pectinatus) as biological factor affecting concentrations of P and chlorophyll a concentrations was tested under laboratory conditions. In general, after four weeks exposition, the significant reduction of TP, P-PO4 and chlorophyll a was observed in all experimental variants (aquaria with P. pectinatus, C. demersum and P. pecinatus + C. demersum), but the highest decrease of phosphorous compounds (TP, P-PO4) was noted in aquarium with C. demersum, whereas the highest decline of chlorophyll a concentration (biomass of phytoplankton) was observed in aquarium with C. demersum + P. pectinatus. Together with the reduction of chemical parameters the biomass of macrophytes as well mean length of plant shoots significantly increases. The highest growth of shoots and biomass showed C. demersum.
The relationships between epiphytic fauna and habitat conditions were studied in three oxbow lakes of Wieprz River (eastern Poland). Fauna associated with macrophytes showed low species richness (range 8–11 taxa dependently on site and season) usually observed in lakes of high water trophy. Densities of fauna were high (mean 71–5250 ind. 100 g DW-1), typical for shallow lakes with well developed submerged vegetation. In the domination structure prevailed Gastropoda (relative abundance 23–100%) and Chironomidae (relative abundance 8–87%). Re-dundancy analysis showed the significance of four environmental variables – temperature, dis-solved oxygen, Ptot and P-PO4 as determinants of abundance of epiphytic fauna.
This paper proposes an inverse method to obtain accurate measurements of the transient temperature of fluid. A method for unit step and linear rise of temperature is presented. For this purpose, the thermometer housing is modelled as a full cylindrical element (with no inner hole), divided into four control volumes. Using the control volume method, the heat balance equations can be written for each of the nodes for each of the control volumes. Thus, for a known temperature in the middle of the cylindrical element, the distribution of temperature in three nodes and heat flux at the outer surface were obtained. For a known value of the heat transfer coefficient the temperature of the fluid can be calculated using the boundary condition. Additionally, results of experimental research are presented. The research was carried out during the start-up of an experimental installation, which comprises: a steam generator unit, an installation for boiler feed water treatment, a tray-type deaerator, a blow down flashvessel for heat recovery, a steam pressure reduction station, a boiler control system and a steam header made of martensitic high alloy P91 steel. Based on temperature measurements made in the steam header using the inverse method, accurate measurements of the transient temperature of the steam were obtained. The results of the calculations are compared with the real temperature of the steam, which can be determined for a known pressure and enthalpy.
Conditions for the positivity of linear electrical circuits composed of resistances, coils, capacitors and voltage (current) sources are established. It is shown that: 1) the electrical circuit composed of resistors, coils and voltage source is positive for any values of their resistances, inductances and source voltages if and only if the number of coils is less or equal to the number of its linearly independent meshes, 2) the electrical circuit is not positive for any values of its resistances, capacitances and source voltages if each its branch contains resistor, capacitor and voltage source, 3) the positive n-meshes electrical circuit with only one inductance in each linearly independent mesh is reachable if all resistances of branches belonging to two linearly independent meshes are zero.
The restoration of the anthropogenic Pławniowice water reservoir with the hypolimnion withdrawal method (the Olszewski's tube) began in December 2003. The decision to restore the reservoir had been taken due to its terrible condition resulting from the hypertrophy, which had been indicated by the research from the years 1993–1998. The following paper presents the results of eight-year-long research into the formation of oxygen conditions and restoration settings. They were compared with the data obtained from the research before the restoration. Positive changes were witnessed. It was showed that grasping the changes in oxygen conditions enables the comparison of oxygen profiles in the same months in subsequent years. The ratio of anoxic water layer thickness to the oxygenated layer thickness was suggested as a factor characterizing oxygen conditions. The area described with an izooxa in the xy coordinate system was suggested as a factor [O2 mg/m2] allowing researchers to understand and describe occurring changes. It was observed that the oxygen solved in water as a result of the restoration occurred in the whole water column in the third decade of July. The oxygen concentration in the hypolimnion gradually rose in May, June and July each year. It was showed that the improvement in oxygen conditions stemmed from progressing oligotrophy of the reservoir.