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EN
Settling of solid particles in a stratifed ambient fuid is a process widely encountered in geophysical fows. A set of experiments demonstrating the settling behaviour (the pattern of trajectory, variation of particle orientation, and settling velocity with depth) of thin disks descending through a nonlinear density transition was performed. The results showed complex hydrodynamic interactions between a particle and a liquid causing settling orientation instabilities and unsteady particle descent in low to moderate Reynolds number regime. Five phases of settling were observed: two phases with stable horizontal, one with stable vertical disk position, and two reorientation phases; moreover, two local minima of settling velocity were identifed. It was demonstrated that thresholds for local minima and the frst reorientation depend on the settling dynamics in an upper layer, stratifcation conditions, and disk geometry. The comparison of settling behaviour of thin disks varying in diameter revealed that settling dynamics is sensitive to particle geometry mainly in the upper part of density transition with a non-obvious result that the frst minimum velocity is smaller for a disk with a larger diameter than for a disk with a smaller diameter. The analysis of settling trajectory showed that two reorientations are accompanied with a horizontal drift, which may be important in the context of interactions between particles settling in a group.
EN
Food is a product that breaks down quickly and easily. Therefore, it require storage at a low and controlled temperature. Maintaining a constant temperature inside the refrigeration furniture requires removal of the heat which enters the interior of the furniture and the heat produced by stored products. The paper presents methods of heat transfer implementation, such as: heat conduction (including fluid stratification case), natural and forced convection and radiation. Heat balance have been presented for selected refrigeration furniture including the characteristics of its individual parameters. A method for determining the components of a heat balance is also presented.
PL
Żywność jest produktem, który szybko i łatwo się psuje, dlatego wymaga przechowywania w kontrolowanej temperaturze. Zachowanie niezmiennej temperatury wewnątrz mebla chłodniczego wymaga odprowadzenia ciepła, które dopływa do wnętrza mebla z otoczenia i ciepła wytwarzanego przez przechowywany produkt. Omówiono sposoby realizacji procesu przepływu ciepła takie jak: przewodzenie ciepła (w tym stratyfikacja), konwekcja naturalna i sztuczna oraz promieniowanie. Przedstawiono bilans cieplny dla wybranych mebli chłodniczych wraz z charakterystyką jego poszczególnych parametrów. Zaprezentowano również sposób pozwalający wyznaczyć składowe bilansu ciepła.
EN
Hot water storage tanks are devices with high energy consumption, used widely in residential, industrial and commercial sectors. The hot storage tank is a key device in numerous applications such as electrical heaters, solar thermal storage, solar electrical energy production and many others. Its superior technology is favorable for the designers and has a great impact on the market competition. Hot water storage tanks were studied under continuous usage feature, for different inlet types, flow rates, thermal stratification in static and dynamic modes, both experimentally and numerically. The real discrete usage feature has not been analyzed in a proper way. In this study, the experimental and performance analyses with frequent discrete usage of the hot storage tank were performed. Different flow rates of 3, 6, and 9 l/min with 5, 10 and 20 min discrete usage waiting periods were studied. It was found that the thermocline thickness and mixing number increases for both increasing the flow rate due the increment in turbulent mixing potential and increasing the waiting period due to the increase in heat transfer time available between the hot and cold layers. The real data was drawn as is to permit further analyses and data comparison to other researchers. The effect of waiting periods can be used in solar HST to maximize the efficiency of solar collectors as the solar collector efficiency is high at low temperatures.
4
Content available remote Analiza stratyfikacji temperaturyw zbiorniku akumulacyjnym
PL
Zużycie ciepłej wody stanowi znaczny udział w bilansie energii budynku. W warunkach polskich jest to około 15%. Obecnie znaczna liczba instalacji c.w. jest wyposażona w zasobniki akumulacyjne. Dlatego wzrost efektywności magazynowania ciepła ma istotne znaczenie. Jednym ze sposobów jej poprawy jest zapewnienie jak najwyższego pionowego uwarstwienia temperatury wody w zasobniku akumulacyjnym polegającym na ograniczeniu do minimum procesu wyrównywania się temperatury. Może to przyczynić się do wzrostu efektywności nawet od 6 do 20% w stosunku do zbiornika z pełnym zmieszaniem. Jest to związane z jakością termodynamiczną czynnika, tzn. im wyższa temperatura, tym wyższa jakość termodynamiczna czynnika. Na pionowe uwarstwienie temperatury wody ma wpływ wiele czynników, takich jak: rozmiary zbiornika, jego kształt, lokalizacja wężownic, króćców zasilających, straty ciepła do otoczenia, konwekcja swobodna, przewodzenie ciepła pomiędzy chłodnymi i ciepłymi warstwami cieczy itp. Zapewnienie jak najlepszego uwarstwienia wymaga odpowiedniego ukształtowania zbiornika, rozmieszczenia elementów znajdujących się w jego wnętrzu tak, aby ograniczyć mieszanie zimnej i ciepłej wody. W pracy przedstawiono wyniki eksperymentalnych pomiarów stratyfikacji temperatury wody w zbiorniku akumulacyjnym przeznaczonym do przygotowania c.w. wyposażonym w trzy wężownicowe wymienniki ciepła rozmieszczone na różnych wysokościach zbiornika oraz układ stratyfikacji temperatury. Głównym celem pracy była analiza procesu stratyfikacji temperatury w zbiorniku akumulacyjnym oraz wpływ parametrów geometrycznych i cieplno – przepływowych na rozkład temperatury wody w zbiorniku. Badania eksperymentalne przeprowadzono dla trzech przypadków: nagrzewania wody w zasobniku przy wykorzystaniu wężownicowego wymiennika ciepła układu odzysku ciepła oraz wężownicowych wymienników zlokalizowanych w dolnej i górnej części zasobnika. Zastosowanie stratyfikatora znacznie poprawia uwarstwienie temperatury w zbiorniku w początkowej fazie pracy wężownicy układu odzysku ciepła jednak w dłuższej perspektywie czasu stosunkowo duża energia kinetyczna transportowanej wody przyczynia się do degradacji uwarstwienia temperatury. Zaobserwowano również, że górna wężownica powoduje zakłócenia procesu stratyfikacji w przypadku pracującej dolnej wężownicy. W związku z powyższym wymagana jest optymalizacja kształtu układu stratyfikacji oraz rozmieszczenia wężownic wewnątrz zbiornika.
EN
Consumption of the domestic hot water (DHW) represents a significant part in the energy balance of the building. In the Poland, it is about 15%. Currently a significant number of installations DHW is equipped with storage tanks. Therefore, the increase in energy storage efficiency is important. One way to improve it is to ensure the highest vertical stratification of the temperature in the storage tank by minimizing the mixing of the hot and cold water. This can contribute to an efficiency increase up to (6 ÷20)%. The vertical water temperature stratification is influenced by many factors such as the size and shape of the tank, location of the heat exchanger coils, heat loss to the environment, free convection, heat conduction between the cold and hot water layers, etc. The paper presents the results of experimental measurements of water temperature stratification in the storage tank equipped with stratification device and three coil heat exchangers located at different levels of the tank. Experimental investigations were carried out for three cases: water heating in a storage tank using a coil heat exchanger for heat recovery and heat exchangers located in the lower and upper part of the tank. The main objective of the study was to analyze the process of temperature stratification in the storage tank and the influence of geometric and thermal-flow parameters on the water temperature distribution. The use of a stratification device greatly improves the temperature stratification, but in the long period of the time the relatively high kinetic energy of transported water contributes to the degradation of temperature stratification. It has also been observed that the upper coil causes interference with the stratification of the water temperature. The shape of the stratification device and the arrangement of the coils within the tank should be optimized to improve temperature stratification level in the storage tank.
EN
The current growth in geotourism requires an urgent development of classifications of geological features on the basis of criteria that are relevant to tourist perceptions. It appears that structure-related patterns are especially attractive for geotourists. Consideration of the main criteria by which tourists judge beauty and observations made in the geodiversity hotspot of the Western Caucasus allow us to propose a tentative aesthetics-based classification of geological structures in outcrops, with two classes and four subclasses. It is possible to distinguish between regular and quasi-regular patterns (i.e., striped and lined and contorted patterns) and irregular and complex patterns (paysage and sculptured patterns). Typical examples of each case are found both in the study area and on a global scale. The application of the proposed classification permits to emphasise features of interest to a broad range of tourists. Aesthetics-based (i.e., non-geological) classifications are necessary to take into account visions and attitudes of visitors.
EN
While modeling water dynamics in dam reservoirs, it is usually assumed that the flow involves the whole water body. It is true for shallow reservoirs (up to several meters of depth) but may be false for deeper ones. The possible presence of a thermocline creates an inactive bottom layer that does not move, causing all the discharge to be carried by the upper strata. This study compares the results of hydrodydynamic simulations performed for the whole reservoir to the ones carried out for the upper strata only. The validity of a non-stratified flow approximation is then discussed.
EN
The paper presents a comparative and statistical analysis of the changes of water quality indices values with depth on the water intake from Dobczyce reservoir. Moreover, seasonal variability of the tested indices was analysed and water quality with its usable values were assessed. Dobczyce reservoir is a 12 km long and 1.0 km wide submountain dam reservoir. The reservoir area at the maximum impoundment level (maximum water level) is 915 ha, its capacity 112.1 mln m3 and mean depth 10.2 m. It is situated 20 south of Krakow, in the malopolskie voivodship, myślenicki county. Raw water from the reservoir is collected on tower intake which makes possible water intake from three depth levels. Real water extraction on the intake is about 1.0 m3 ∙s-1, guaranteed 2.5 m3 ∙ s-1 and permissible 5.5 m3 ∙ s-1. The investigations conducted in 2008 and 2009 covered selected physicochemical water indices: the temperature, pH, turbidity, electrolytic conductivity, total suspended solids, dissolved oxygen, oxygen saturation, silica, phosphates, total phosphorus, as well as bioindicator – chlorophyll „a”. At weekly intervals, water samples for laboratory analyses were collected from three depth levels of the reservoir directly at the tower water intake for Krakow. Physicochemical and biological analyses, using referential methods were conducted in the Laboratory of the Municipal Waterworks and Sewer Enterprise in Krakow. For each analysed index mean values for 2008 and 2009 and for the 2008–2009 period of analyses were computed, divided into the winter (October-March) and summer (April-September) half year and for the calendar year (January-December). Statistical significance of the differences between the values of individual indices registered on various depth levels on the reservoir were estimated by nonparametric U Manna-Whitney’a significance test, on α = 0.05. For all investigated indices box-whiskers plots were made which suggestively presented the median, extreme values and 10–90% percentiles. The assessment of Dobczyce reservoir water for drinking water supply for people was conducted following the methodology described in the Regulation of the Minister of the Environment [Dz. U. 2002 Nr 204, poz. 1728]. Selected quality parameters of the tested water were also confronted with the requirements stated in the Regulation of the Minister of Health dated 29 March 2007 on drinking water quality for people [Dz. U. 2007 nr 61, poz. 417]. Trophic state of Dobczyce reservoir was assessed on the basis of total phosphorus and chlorophyll „a” concentrations, using the criteria stated by OECD. On the basis of data analysis it was established that mean annual values of water temperature, pH, oxygen saturation and concentrations of dissolved oxygen and chlorophyll „a” were decreasing with depth. On the other hand, in the vertical profile, turbidity, electrolytic conductivity, as well concentrations of total suspended solids, phosphates and total phosphorus were increasing. Higher water temperatures and pH values were noted in the summer half-year, whereas dissolved oxygen, oxygen saturation and phosphates in the winter half-year. On average for the investigated period, water collected in Dobczyce reservoir on the depth of 3.55 and 9.65 m was classified, respectively to A2 and A3 water category, therefore it required appropriate typical or high performance typical treatment. On the other hand, due to low oxygen saturation in the summer half-year, water on the level of 15.87 m did not meet the standards. Irrespective of the depth, pH and salinity fulfilled the requirements for water intended for direct consumption by people, whereas water turbidity was unsatisfactory all the time. Mean annual concentrations of total phosphorus qualify water collected in the reservoir as mezotrophic, while average and maximum concentrations of chlorophyll „a” allow to regard the water as respectively mezotrophic or eutrophic. Due to relatively big differences in values of the analysed indices, better quality raw water intended for running water outside the growing period supply should be skillfully collected from various depths – generally in the from the shallowest level, in the vegetation season from the middle level and from the lowest level on case higher concentrations of chlorophyll „a” and plankton occur on the first two depths of the reservoir.
EN
In our intraseasonal variability studies of currents in the coastal sea of the Gulf of Finland northeast of Pakri Peninsula, we compared the observation data from a bottom-mounted ADCP (March–June of 2009, 50 m depth) with the simulation data from High Resolution Operational Model of the Baltic (HIROMB). The structure of the current pattern appeared strongly dependent on the stratification conditions. The flow was quasi-barotropic during the periods of weak inverse thermal stratification at the end of winter season and at transition from the inverse thermal stratification to summer type stratification when the sea was thermally unstratified, but mostly two-layered (baroclinic) when the summer type thermal stratification had developed. The alternation of strong westward (eastward) currents (up to 30 cm s-1) in the upper layer is explained in terms of coastal upwelling (downwelling) due to favourable background winds. The measured and the modelled upper layers along isobath currents showed a noticeable correlation with the correlation coefficient of 0.52 and 0.82 during the periods of winter type and summer type stratifications, respectively, and the absence of a significant correlation during the transition period. The eastward (upwind) current episodes with speeds reaching 18 cm s-1 below the seasonal thermocline are likely to reflect the specific circulation response in the elongated basin caused by the easterly wind. The long-term mean (over 3.5 months) current vector (−2.0 cm s-1, −2.9 cm s-1) was westward in the upper sea and eastward, nearly along isobaths (1.1 cm s-1, −0.3 cm s-1) in the deeper layers.
EN
The epilimnetic and metalimnetic phytoplankton assemblages were compared in two mesotrophic lakes (L. Hańcza and L. Dejguny, northeastern Poland) and a “metalimnetic niche” is described. Phytoplankton analysis conducted during July and August 2006, 2007, and 2008 indicated that the total phytoplankton biomass in both lakes was relatively small (from 0.6 to 5.2 mg dm-3), with maximum values mainly occurring in the metalimnion. The lowest number of species and diversity indices values were usually observed in the metalimnetic layers. Lake Hańcza was dominated by diatoms (e.g. Cyclotella spp.) whereas Lake Dejguny was mainly dominated by cyanoprokaryotes (e.g. Planktothrix agardhii), with a distinct predominance of diatoms (e.g. Tabellaria flocculosa) in 2007. The common features of the phytoplankton assemblages in both lakes were a tolerance to nutrient and light deficiencies. A cluster analysis of the taxonomic patterns indicated large dissimilarities between the lakes. The phytoplankton assemblages developed under the influence of seasonal conditions, especially in Lake Hańcza. The distinction between metalimnetic and epilimnetic phytoplankton assemblages only appeared in Lake Dejguny.
PL
W artykule przedstawiono problemy związane z zabezpieczeniem eksploatacji w zachodniej części rowu II-rzędu, gdzie stwierdzono występowanie struktury geologicznej, w granicach której wydzielono dwa rejony zagrożeń, rejon X/S (w zakresie rzędnych +90/ -25 m n.p.m.) oraz rejon XV/S (20/ -110 m n.p.m.) W trakcie prowadzenia eksploatacji w piętrach VII i VIII, dochodziło do rozwoju niewielkich osuwisk oraz obserwowano reakcje reperów powierzchniowej sieci obserwacyjnej. W marcu 2011 roku, w czasie realizacji zabierki w piętrze VIII (eksploatacja do rzędnej +20 m n.p.m.), doszło do rozwoju osuwiska i strefowego wyparcia poziomu na wysokość ok. 3-4 m . Obserwacje wskazywały na możliwość rozwoju wieloskarpowego osuwiska, które utrudni eksploatację w strefie do rzędnej -110 m n.p.m. Podczas eksploatacji w VIII i IX piętrze górniczym, poprzez zestramianie zbocza oraz kontrolowane prowokowanie pełzania osuwającego się fragmentu zbocza, wyeksploatowano znaczny fragment osuniętych gruntów. Pozwoliło to na ograniczenie zagrożeń dla eksploatacji w zakresie rzędnych -20/-110 m n.p.m.
EN
Problems connected with securing exploitation in the western part of II-order graben were presented in paper. Occurrence of geological structure was noted in that area, in which two hazardous areas were distinguished. Area X/S (ordinate +90/-25 m a.s.l) and area XV/S (20/-110 m a.s.l). During exploitation in levels VII and VIII, expansion of small landslides and reaction of superficial observation network bench marks occurred. In march 2011, during exploitation in level VIII (exploitation to ordinate +20 m a.s.l), expansion of landslide and zonal displacement of level, up to 3-4 m occurred. Observations showed possibility of multiscarp landslide, that will make exploitation difficult in zone, up to ordinate -110 m a.s.l. During level VIII and IX exploitation, sloping of slide and controlled provoking of crawling of sliding bevel was performed. During that, part of slided part was exploited. That allowed to limit the hazards for exploitation in ordinates -20/-110 m a.s.l.
11
Content available remote Klasy próżniacze w realiach świata konsumpcji
PL
Myślą przewodnią artykułu jest diagnoza czynników wpływających na tworzenie się tak zwanych nowych klas próżniaczych oraz pokazanie struktury zawodów uznawanych przez społeczeństwo polskie za klasy próżniacze. Ideą przedstawionych treści jest ukazanie historycznych uwarunkowań powstawania klas próżniaczych oraz teoria klas próżniaczych rozpatrywana w kategoriach uwarstwienia społecznego. Jeden z obszarów badań stanowiło teoretyczne ujęcie stratyfikacji społecznej. Szczególny nacisk autor położył na strukturyzację zawodów w odniesieniu do skali prestiżu w Polsce, w tym również pozycji zawodu żołnierza.
XX
The purpose of this article is to diagnose the factors affecting the formation of the so-called idle classes, and to show the structure of professions recognized by the Polish society as an idle class, including the profession of a soldier. Referring to the sources of cognitive phenomena should emphasize its historical context. The formation of idle class has its origins along with creating the primitive forms of social differentiation. This institution is an effect of stratification and has a permanent place in the coexistence of groups, classes and social units. In order to fully understand the topic, the question of social inequality in theoretical was presented, as well as structuring the competition for the prestige scale in Poland.
PL
W artykule przedstawiono zagrożenia osuwiskowe występujące w trakcie prowadzenia eksploatacji w rowie II rzędu, tj. w najgłębszej części złoża Bełchatów. Omówiono główne tektoniczne granice struktury oraz ich wpływ na bezpieczeństwo robót górniczych. Artykuł zawiera dokładną charakterystykę strefy uskokowej tzw. uskoku północnego brzeżnego (UNB nr 2), udokumentowaną w trakcie prowadzenia eksploatacji. Zrzut uskoku notowany w podłożu mezozoicznym wynosi od 60 do 200 m. Charakter strefy ulega zmianie od rozległej fleksury do szeregu powierzchni uskokowych o zróżnicowanym kącie i kierunku upadu. Ciekawym elementem tej strefy są pojawiające się coraz częściej powierzchnie nasunięć zlokalizowane po północnej stronie uskoku. Drugim istotnym elementem scharakteryzowanym w artykule jest blok skał mezozoicznych budujących południowy brzeg rowu Kleszczowa. Strefa ta zwana blokiem paleoosuwiskowym (BP) zlokalizowana jest na południowym uskoku brzeżnym Rowu Kleszczowa tzw. USB nr 1. Blok paleoosuwiskowy ma długość około 1700 metrów i jest prawdopodobnie szeregiem bloków przesuniętych ku północy poza górną krawędź uskoku USB nr 1 na odległość około 140 metrów w efekcie starych osuwisk. Szacunkowa objętość BP wynosi około 118 mln m3 przy udokumentowanej miąższości 260 metrów. W granicach BP wykartowano do tej pory 11 mniejszych bloków zalegających w obrębie osadów trzeciorzędowych. Przedstawiono wyniki dotychczasowych prac terenowych zmierzających do rozpoznania deformacji wewnętrznych BP. Zwrócono uwagę na praktyczny aspekt rozpoznania struktur powodujących wewnętrzną anizotropię bloku, jako elementu niezbędnego dla prawidłowego planowania i bezpiecznego prowadzenia robót górniczych.
EN
In this article described landslide hazards occur while mine technology for extraction in II order graben, the deepest part of the brown coal deposit Bełchatów. Discussed major tectonic structure have influence to safe mine extraction. The article contains precise characteristic fault line called "North border fault line" (UNB no. 2) documented while mine extractions. Drop has been recorded in the Mesozoic substratum and amount 60 to 200 meters. The style of zone is varied from expansive flexure to series fault lines varied angle and dip direction. Interest aspect of this zone is appearing more often imply surfaces in the north side of fault line. The second important aspect described in this article is block of Mesozoic rock which is building south border Kleszczow graben. The zone called paleolandslide block (BP) is locating in the south border fault line Kleszczow graben called USB no. 1. Paleolandslide block is 1700 meters long and it is probably blocks group move to the north board fault line USB no. 1 about 140 meters bring about old landslide. Estimate volume BP is 118 mln m3 with documented depth 260 meters. In the board BP charted 11 lower block group deposit in the Tertiary sediments. Described results previous field work driving to better knowledge deformations inside BP. It was taken note of practical aspect recognition structure cause steady inside block as necessary element to right planning and safe mining extraction.
PL
W pracy zbadano zjawisko rozwarstwiania nasion podczas wypływu z silosów z wypływem lejowym. Materiałem użytym do badań były nasiona rzepaku. Badania przeprowadzono w trzech typach silosów SZD o pojemności 40 m3. Celem badań było określenie, w jaki sposób dodatkowe elementy umieszczone w silosie wpływają na segregację mieszaniny nasiennej rzepaku. Stwierdzono wyraźne rozwarstwienie nasion w silosach z promieniowym i pionowym układem wietrzenia w porównaniu z silosem bez układu wietrzącego. Zaleca się żeby w tych silosach ostatnią partię nasion stanowiącą 15% objętości zbiornika poddać ponownemu czyszczeniu.
EN
The study deals with the question of size stratification of seeds during the funnel flow from a silo. Oilseed rape seeds were used for the tests. The experiment was carried out in three types of SZD silos, each 40 m3 in capacity. The purpose of the study was to determine how some additional elements in a silo affected the segregation of a seed mixture. In silos equipped with vertical or radial ventilation systems, seeds were size stratified, whereas in silos without a ventilation system seed stratification was much less efficient. It is, therefore, recommended to further clean the last 15% of grain removed from the latter types of silos.
EN
The problem of unsteady free convection heat transfer from a one-dimensional (parallel) flow along an infinite verticaI fiat plate embedded in a thermaIly stratified fluid-saturated porous medium is considered. FIows are induced by a step change in surface temperature or heat flux. By a formaI reduction of the corresponding boundary vaIue problems to well known Fourier heat conduction problems, analytical solutions of the Darcy and energy equations are obtained.
EN
The results of long-term research confirm that Lake Czarne in the Drawieński National Park is meromictic due to natural factors, not human influence. The lake is located in a large natural basin, so the tall forest stands covering the steep slopes surrounding the lake protect it from strong winds. Its small surface area and relatively large mean and maximum depth also limit the possibilities of water mixing in the lake.
EN
Five years (1998, 2000-2003) of summer records of temperature, nutrients and dissolved oxygen concentrations in the upper 400 m of the water column of the northern Gulf of Aqaba were employed to produce a simple statistical model of the relationship between temperature versus nitrate, phosphate, silicate and dissolved oxygen concentrations. Temperature profiles in the upper 400 m during summer revealed a clear thermocline in the upper 200 m. This was reflected in nutrient and oxygen concentrations as nitrate, phosphate, and silicate increased from the surface to deep water while dissolved oxygen decreased. The best fit relationship between temperature versus nitrate and phosphate was inverse linear and the best fit correlation between temperature versus silicate and dissolved oxygen was fractional. The observed nutrient concentrations were shaped by a combination of the hydrodynamics and biological factors. Deep winter mixing and high nutrient concentrations dominate during winter. Shortly after the water stratifies in spring, the nutrients are drawn down by phytoplankton during the spring bloom and remain low throughout the rest of the year. The regression equations presented here will be useful in estimating nutrient concentrations from temperature records as long as the annual natural cycle is the main driver of nutrient concentrations and external inputs are insignificant. Deviations from these relationships in the future could provide insight into modifications in the nutrient concentrations probably resulting from new nutrient sources, such as anthropogenic inputs.
17
Content available remote Sediment cores from river dams as flood archives
EN
Studies of sediment cores originating from a dam of the River Mulde near Bitterfeld (Saxony-Anhalt, Germany) confirmed that river dams act as excellent archives of flood events. The records were performed by significant changes of the composition and quality of suspended matter and sediment. To combine the investigated sediment core with a reliable time scale, suitable reference data (e.g. radionuclides, geochemical markers) were included into the study. Subsequently, flow data of the Mulde (from 1975 up to now) were used to assign specific floods (>300 m3/s) to the event layers detected in the sediment cores. In addition to this, further time markers were inspected towards a more reliable adjustment of the time scale. In detail we made use of the 137Cs activity maximum (caused by Chernobyl fallout), as well as of the drop in organic pollution (following the collapse of East Germany's industrial sector 1989/90), and finally of the decrease in the concentration levels of elements and isotopes (a consequence of the reduced activities of mines and metallurgical plants in the River Mulde catchment). Exemplarily we present the results for a short sediment core, which originates from the Friedersdorf basin of the Mulde river dam (sampled in September 2002). The most recent such layer occurring in this sediment core was caused by the flood in August 2002. This event proved to be an outstanding flood time marker with regard to its thickness and geochemical properties.
18
Content available remote Effects of design and flow conditions on the losses of hot water storage tanks
EN
In this paper the author describes a method which is being developed for calculation of the energetic and exergetic losses of hot water storage tanks (HWST). As input data for the calculation only the details of design, materials and main aspects of intended operation conditions are to be included. Based o experimental investigations and extensive numerical modeling with the CFD-code Fluent, semi-empirical correlation was developed as a tool for storage tank designers. In this way, tank losses could be approximated already at the time of tank design and a lot of experimental tast could be avoided.
19
Content available remote Zbiorniki akumulujące ciepło w systemach pozyskiwania energii słonecznej
PL
W artykule omówiono czynniki warunkujące uzyskanie pożądanego rozkładu temperatury w zbiornikach akumulujących ciepło, przedstawiono przykładowe rozwiązania konstrukcyjne.
EN
Factors influence the proper stratification in the storage tanks. Selected constructional solutions of hot water storage tanks in solar installations.
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