Current Issue : April - June Volume : 2018 Issue Number : 2 Articles : 5 Articles
Operational and economic aspects of water distribution make water demand forecasting paramount for water distribution systems\n(WDSs) management. However, water demand introduces high levels of uncertainty in WDS hydraulic models. As a result, there\nis growing interest in developing accurate methodologies for water demand forecasting. Several mathematical models can serve\nthis purpose. One crucial aspect is the use of suitable predictive variables. The most used predictive variables involve weather and\nsocial aspects. To improve the interrelation knowledge between water demand and various predictive variables, this study applies\nthree algorithms, namely, classical Principal Component Analysis (PCA) and machine learning powerful algorithms such as Self-\nOrganizing Maps (SOMs) and Random Forest (RF). We show that these last algorithms help corroborate the results found by\nPCA, while they are able to unveil hidden features for PCA, due to their ability to cope with nonlinearities. This paper presents a\ncorrelation study of three district metered areas (DMAs) from Franca, a Brazilian city, exploring weather and social variables to\nimprove the knowledge of residential demand for water. For the three DMAs, temperature, relative humidity, and hour of the day\nappear to be the most important predictive variables to build an accurate regression model....
Currently an international topicââ?¬â?not only among the members of the European Unionââ?¬â?is\nthe use of renewable energy, such as hydro power. The subject of this paper is the environmental\nimpact assessment of the small hydropower (SHP) plant. The paper identifies the environmental\nimpacts of an SHP plant in SpiÃ?¡skÃ?© BystrÃ?©, Slovakia. It also assesses the alternatives to a specific\nhydraulic structure by quantitative evaluation from the point of view of character of the impacts,\ntheir significance, and their duration. The conclusion of the work includes the selection of the optimal\nalternative of the assessed construction and proposes measurements to reduce the negative impacts.\nThe benefit of this paper is in highlighting the importance of assessing the impact of construction\non the environment in the planning phase. Eliminating the negative impacts of the construction on\nthe environment is much more challenging than the implementation of preventive measures, and it\nis therefore necessary to assess at the planning phase how the construction and operation of the\nproposed activities impact the environment....
In Lake Iseo (Lombardia, Italy), the predominant species in the cyanobacterial taxa\nwas Planktothrix rubescens. However, since 2014, the presence of an allochthonous Cyanobacteria,\nTychonema bourrellyi, able to produce consistent biomasses and harmful toxins, was detected.\nThe causes of this expansion are poorly understood. Many studies have linked the development of\nallochthonous Cyanobacteria populations with climate change. This study shows the spatio-temporal\ndynamics, the ecological requirements, and the interspecific relationship of P. rubescens and\nT. bourrellyi. Samples were collected monthly in 2016 at six different depths in the water column;\n20 chemico-physical characteristics were measured; and Cyanobacteria density, morphology,\nand biovolume were evaluated. The results allowed a comparison of the spatial pattern of the\ntwo species, which showed a greater distribution at a depth of 10ââ?¬â??20 m, and their seasonal dynamics.\nBoth Cyanobacteria were present throughout the year, with the greatest abundance during the\nperiod from March to May. A temporal shift was observed in their development, linked to different\ncapacities for overcoming winter and mixing periods. Principal Component Analysis, performed on\n20 observations (4 months Ã?â?? 5 depths), highlighted the important role of the stability of the water\ncolumn in determining T. bourrellyi settlement in Lake Iseo and the role of solar radiation in spring\npopulation development....
Pervious concrete is considered to be an advanced pavement material in terms of the\nenvironmental benefits arising from its basic featureââ?¬â?high water-permeability. This paper presents\nthe results of experimental work that is aimed at testing technically important properties of pervious\nconcrete prepared with three different water-to-cement ratios. The following properties of pervious\nconcrete were testedââ?¬â?compressive and splitting tensile strength, unit weight at dry conditions, void\ncontent, and permeability. The mix proportions were expected to have the same volume of cement\npaste, and, to obtain the same 20% void content for all of the samples. The results show that changes\nof water-to-cement ratio from 0.35 to 0.25 caused only slight differences in strength characteristics.\nArising tendency was found in the case of compressive strength and a decreasing tendency in the\ncase of splitting tensile strength. The hydraulic conductivity ranged from 10.2 mm/s to 7.5 mm/s.\nThe values of both the unit weight and void content were also analysed to compare the theoretical\n(calculated) values and real experiment results. A fairly good agreement was reached in the case of\nmixtures with 0.35 and 0.30 water-to-cement ratios, while minor differences were found in the case of\n0.25 ratio. Finally, a very tight correlation was found between void content, hydraulic conductivity,\nand compressive strength....
The aim of this paper was to study of utilization of converter sludge waste as a sorbent.\nThe sorbent was utilized to reduce the content of manganese, cobalt, and nickel ions from mine\nwater. Sorbent utilized in this work was obtained from the metallurgical industry from a process\nof gas treatment in an oxygen converter. Converter sludge was characterized by X-ray diffraction,\nScanning Electron Microscope, X-ray fluorescence spectroscopy, Specific Surface Area and Particle\nSize. Sorption experiments were conducted in a batch mode by using the real mine water. The impact\nof pH and contact time on the pollutant removal efficiency was observed. The sorption kinetics\nwere evaluated with pseudo-first and pseudo-second order kinetic models. For the tested materials,\nthe highest level of mine water purification was achieved; thus, the mine water could be discharged\ninto the watercourse. The results of this study indicate that the application of metallurgical waste as\na sorbent is highly effective for the treatment of multicomponent mine water....
Loading....