Proper design of hydrotechnical structures should meet the basic principles of sustainable development, i.e., the investment should be designed and made in technical terms, in accordance with the ...applicable standards and regulations, provide certain economic benefits and guarantee the absence of environmental hazards. The article examines the work of a Small Hydropower Plant (SHP) in Jaracz in technical and hydraulic terms. It also provides the analysis of the effect of changes in parameters such as water head, flow rate velocity, and shape of trash rack bars on expected SHP profits. The assessment of hydraulic performance consisted of investigating the impact of reduced flow rate and water head on power output and energy production. The analyses were carried out for the Francis turbine installed in the facility. Since the loss of channel capacity is shaped by plant debris accumulated on trash racks, the hydraulic performance assessment was extended to include the analysis of the species and weight composition of such accumulation on fine trash racks located in the inlet channel. Field research involved collecting organic material from the growing season (spring, summer) and post-growing season (autumn). Technical conditions were developed on the basis of the current technical condition of the inlet channel; there were also made simulations of its deteriorating state, as well as its impact on the received energy and economic benefits.
Helicobacter pylori - (H. pylori) play a role in the pathogenesis of gastritis, gastric and duodenal ulcers as well as gastric cancer. A possible involvement of outer membrane vesicles (OMVs) ...produced by H. pylori in the distribution of bacterial antigens through the gastric epithelial barrier and their role in the development of local and systemic host inflammatory and immune responses has been suggested. OMVs contain various biologically active compounds, which internalize into host cells affecting signaling pathways and promoting apoptosis of gastric epithelial and immunocompetent cells. OMVs-associated H. pylori virulence factors may strengthen or downregulate the immune responses leading to disease development. This review describes the biological importance of H. pylori OMVs and their role in the course of H. pylori infections, as well as H. pylori related local and systemic effects.
There is currently a growing trend towards renewable energy sources, which are characterised by a guaranteed power supply and low failure rate. Hydropower plants (small or large) are an example of ...such a source. They supply a total of 16% of the world’s electricity. The advantages of a small hydropower plant include the relatively simple construction process and the lack of need for upstream water storage. SHPs are one of the most cost-effective and environmentally friendly energy technologies, which is why they are steadily increasing in popularity. One of the important components of SHPs are the trash racks in the inlet channels. Their main purpose is to catch debris and other elements carried downstream and to prevent these pollutants from reaching the turbine units. They can also protect migrating ichthyofauna such as larger fish. If trash racks are installed in the inlet channel, hydraulic losses are to be expected due to the reduction in the flow cross-section through the racks (bars) themselves and through the accumulation of debris and various types of trash on these racks. Energy losses on the trash racks affect the financial aspect of SHP investments. This paper presents the results of laboratory tests on trash racks for SHPs by taking into account the different shapes of the bars used, their number and spacing, and the angles of the trash racks to estimate the hydraulic losses on the trash racks. The measured values of hydraulic losses Δh on the trash racks varied according to the type of trash racks, the density of the bars in the cross-section, and the angle of the trash racks from the horizontal, reaching the highest values on the trash racks with angle bars (AB). They were almost eight times greater than those recorded on cylindrical-bar (CB) trash racks, although they involved different angles. It was shown that the discrepancy in the magnitude of losses on trash racks can be large, even for the same type of trash racks. It depends significantly on the design (shape and bar spacing) of the trash racks and the way the trash racks are installed. Depending on the inclination angle, the increase in energy losses reached 70% for angle bars, 60% for flat-bar trash racks, and almost 40% for cylindrical bars. The values of energy loss as well as the loss coefficient β varied non-linearly for the different bar types depending on the angle of inclination of the gratings, and the degree of this non-linearity depended on the type of bars and the blockage ratio of the section. The presented research results can be useful both during the design and the operation of an SHP.
Deposition of debris on the screens of hydroelectric power plants translates into measurable economic losses. Occurring plant debris, although it is an organic material, is characterised by different ...forms and structure. It is often leaves, branches, and grasses in lowland areas, while in mountainous regions, broken boughs and trees can be expected. On the trash racks of power plants, debris may be deposited in different forms, shapes, and places. This work aims to determine the impact of the degree of submergence of debris on the values of the force acting on the racks. This paper analyzes the influence of the rectangular shape of the debris deposited on the trash racks and its degree of submergence and weight on the obtained values of the force acting on the racks as a result of water pressure, which directly affects the hydraulic losses and productivity of hydroelectric power plants. Our research confirms the negative influence of the deposited plant debris on the value of forces recorded on the gratings. The increase in the recorded force, and thus the resistance on the grating, is obviously dependent on the degree of obstruction of the debris by the grating obtained by changing the degree of debris immersion and its weight. In the case of changing the degree of submergence, the increase in force recorded on the gratings varied during the experiment from about 25% recorded for the fully submerged debris compared to that of the partially submerged debris for the mass of 100 g; in comparison, an increase of about 31% was recorded for that of the mass of 200 g. However, comparing the values of the forces recorded on the obstructed grids to that of the forces recorded on the clean grids, the increase ranged from about 15–53%.
Small hydropower plants are one of the most important renewable energy sources that do not degrade and consume natural resource. The paper presents a case study of an already operating small ...hydropower plant (SHP) and a potential increase in its energy production by raising the damming level. Three variants were defined and subjected to detailed analysing. The analyses used the Fuzzy AHP methodology (FAHP), which allowed for identifying the variant that has the best chance of being implemented in the context of administrative, legal and social realities of the country where an SHP is located. The adopted solution will increase electricity production by 108.78 MWh annually, while reducing carbon dioxide emissions by 86000 kg CO2. The described methodology is of general use and can be applied in any country in the world.
•The FAHP method was used to select the optimal variant of increasing the SHP damming level.•The proposed variant A1 will enable increased "green" energy production, and provide the best chances for implementation.•Variant A1 will enable an increase in electricity production by about 110 MWh per year and reduce CO2 emissions by 86,000 kg.•The proposed methodology can also be easily used for analysis and optimisation of other SHP facilities.
The operation of water structures causes various problems. They are related, for example, to the material carried by the water, hydrological conditions, range of operation of hydroelectric turbines, ...or water elevations at the lower position of the hydroelectric power plant. Among the various operational problems, this article focuses mainly on the impact of the backwater of Gwda river on the water level elevations at the lower station of the Stary Młyn hydropower plant in Dobrzyca. The power plant is located on Głomia river. The analysis was carried out for different flow variants in both the Gwda and Głomia rivers. The effect of characteristic flows on the water surface level at the lower station of the hydropower plant was examined. It was found that the water surface level at the lower station of the hydropower plant is strongly influenced by flows higher than the average high flow on Gwda river. Due to the extent of the backwater in current operating conditions, the hydroelectric power plant is shut down from flows on Gwda river of 30–28 m3/s (flows that are not much higher than the multi-year average SSQ). The modeling results were confirmed by an analysis of power plant shutdowns of normal operation especially in wet years, when the plant did not operate for almost half of the year (188 days), with losses of 203 MWh. It was also shown that even a small additional damming of water, e.g., of the order of 0.2 m, can extend the operating time of a power plant up to 249 days even under unfavorable hydrological conditions. Factors related to climate change are beginning to play an increasingly important role in the current operating conditions of small lowland hydroelectric power plants. They can contribute to a reduction in electricity production. The proposed solution related to the possibility of greater water retention on dammed-up water barrages allows one to partially offset these problems as well.
Considering the limited capabilities of obtaining energy in a traditional way from coal combustion and the requirements of the European Union, other alternative energy sources should be sought. They ...have been being increasingly used by business entities and individual investors and are designed to provide financial profits, which will be ensured only with correct operation of the energy system. One of examples of alternative energy sources application is the construction of small hydropower plants, where the efficiency of all elements included is of great importance. The article analyses financial losses incurred by owners of power plants when the energy system lacks 100% capacity of the inlet channel. Material that accumulates on SHP trash racks might be analysed in two ways: biologically (these are screenings – as in wastewater treatment plants) and hydraulically.
One of the biggest threats to many lakes is their accelerated eutrophication resulting from anthropogenic pressure, agricultural intensification, and climate change. A very important element of ...surface water protection in environmentally conserved areas is the proper monitoring of water quality and detection of potential threats by examining the physicochemical properties of water and performing statistical analyses that enable possible exposure of unfavourable trends. The article presents the analyses of the results of measurements made in three lakes located in the Sierakowski Landscape Park. As part of the measurements, water quality indicators i.e., phosphorus, nitrogen, BOD5 and COD, were determined monthly for a year at the inflows and outflows of the studied lakes. The test results of selected water quality indicators were analysed using machine learning algorithms i.e., PCA and k-means. The conducted tests enabled statistical estimation of changes in water quality indicators in the reservoirs and evaluation of their correlation.
Trash racks are the first element mounted in inlet channels of hydraulic structures. Their primary task is to capture coarse pollutants flowing in the riverbed/river channel and protect water ...facilities downstream. With the use of these devices, it is possible to separate coarse suspended matter, branches carried with the current, floating plastic elements, etc., which undoubtedly contributes to a trouble-free flow through culverts or channels and prevents hydroelectric power plant turbines from failure. An important issue here is also to ensure the proper operation of trash racks, particularly in respect of hydraulic structures whose task is to convert water energy into electricity (hydropower plants). Proper operation of trash racks minimizes losses arising from obstructing the free flow of water through accumulated waste or, in the wintertime, through icing. Incorrect work in this area entails specific head losses, and consequently leads to economic harm. In the paper, the resistance values of trash racks were analyzed at small hydropower plants (SHPs) operating at low temperatures, determined under laboratory conditions, with the occurrence of frazil ice and ice. The results indicate that the added ice into the channel resulted in the formation of a cover in front of the trash racks with an average thickness of about 0.02 m. The accumulated ice increased the head losses up to 14%. The range of the ice cover depended on the weight added ice and reached 0.6 m in analyzed cases.
This paper presents the efficient reduction of phosphinoylacetic acid esters and 3-phosphorylated coumarin to their corresponding phosphino-boranes using BH₃-THF complexes. Optimized conditions for ...the reduction of phosphinoylacetic acid esters resulted in high yields of phosphinoborates. The straightforwardness and efficiency of the process were demonstrated for diarylphosphinoylacetic acid ethyl esters, as well as P-stereogenic L-menthyl esters, where the simultaneous reduction of the strong P=O bond and the ester group was exclusively observed for the first time. The study also highlighted the significant influence of steric effects with bulky substituents, such as the menthol group or the 1-naphthyl substituent at phosphorus, on the reduction efficiency. However, the reduction of 3-phosphorylated coumarins produced an unexpected reaction product: a 2,3-dihydrobenzofuran derivative. The present findings provide valuable information on the direct reduction of phosphine oxides and related compounds, demonstrating the versatility of borane complexes in synthetic chemistry, and provide new perspectives for studying the problems of symmetry and asymmetry in the chemistry of such transformations.
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