Given the concern for maintaining voltage stability in power systems integrated with renewable power systems due to a mismatch in generation and demand, there remains a need to invoke flexible ...alternating current transmission system (FACTS) devices in the distribution network. The present paper deals with identifying the locations of placement of a static var compensator in an experimental IEEE 14-bus system; the voltage drop in different buses in an IEEE 14-bus system is calculated by the standard formula. The total voltage drop in the network (TVDN) is also calculated as a reference. The ranking of buses in order of decreasing voltage drop is made, and the weak buses are identified as those showing the maximum or near-maximum voltage drop for the installation of a Static Var Compensator (SVC). The optimum usable size is calculated using a Genetic Algorithm approach to optimize the installation cost. After size optimization, installing a 2 MW solar generator is considered for the weak and most potential bus, which suffers from voltage drops or power loss. Based on the generator at the weakest bus, the total power loss in the network is calculated and compared with a similar method to assess the efficiency of the proposed model. Thus, the voltage stability enhancement problem is solved by applying a Genetic algorithm (GA) to optimize SVC size and using the Total Voltage Drop in Network (TVDN) method to identify weak buses in the systems. It is found that the performance of the proposed system is comparable with another existing system. It is further observed that a gain in power loss to 6.56% is achievable by adopting the proposed strategy, and the gain is better than the other system.
Chemical composition of bottled water on Croatian market Ptiček Siročić, Anita; Dogančić, Dragana; Bosilj, Mateja
e-zbornik. Elektronički zbornik radova Građevinskog fakulteta,
6/2023, Letnik:
13, Številka:
25
Journal Article
Recenzirano
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The Ordinance on natural mineral, natural spring and table waters regulates the market of bottled water. The Directive on the quality of water intended for human consumption sets water quality ...standards and three categories of parameters (microbiological, chemical and indicator). Microbiological parameters show the degree of water pollution by microorganisms, while chemical parameters show the degree of water pollution by different chemical substances. Natural spring and natural mineral water have a certain chemical composition in which the concentrations of individual elements have the prescribed maximum allowable amount. If the concentrations of individual elements exceed the maximum allowed amount, they can have a harmful effect on the human body. All categories of bottled water (table, spring and mineral) can be carbonated and non-carbonated, depending on the carbon dioxide (CO2) content. Due to extracting and bottling of drinking water, in order to improve its quality, it is necessary continuously conduct analyses that prove the safety of drinking water.
The main aim of this study is to comprehensively analyze the dynamics of land use and land cover (LULC) changes in the Bathinda region of Punjab, India, encompassing historical, current, and future ...trends. To forecast future LULC, the Cellular Automaton–Markov Chain (CA) based on artificial neural network (ANN) concepts was used using cartographic variables such as environmental, economic, and cultural. For segmenting LULC, the study used a combination of ML models, such as support vector machine (SVM) and Maximum Likelihood Classifier (MLC). The study is empirical in nature, and it employs quantitative analyses to shed light on LULC variations through time. The result indicates that the barren land is expected to shrink from 55.2 km2 in 1990 to 5.6 km2 in 2050, signifying better land management or increasing human activity. Vegetative expanses, on the other hand, are expected to rise from 81.3 km2 in 1990 to 205.6 km2 in 2050, reflecting a balance between urbanization and ecological conservation. Agricultural fields are expected to increase from 2597.4 km2 in 1990 to 2859.6 km2 in 2020 before stabilizing at 2898.4 km2 in 2050. Water landscapes are expected to shrink from 13.4 km2 in 1990 to 5.6 km2 in 2050, providing possible issues for water resources. Wetland regions are expected to decrease, thus complicating irrigation and groundwater reservoir sustainability. These findings are confirmed by strong statistical indices, with this study’s high kappa coefficients of Kno (0.97), Kstandard (0.95), and Klocation (0.97) indicating a reasonable level of accuracy in CA prediction. From the result of the F1 score, a significant issue was found in MLC for segmenting vegetation, and the issue was resolved in SVM classification. The findings of this study can be used to inform land use policy and plans for sustainable development in the region and beyond.
The adverse effects of improper disposal of collected and treated wastewater have become inevitable. To achieve the desired environmental standards, in addition to the construction of wastewater ...treatment plants, there is also a need to evaluate the continuous performance of treatment systems. In Iran, treated wastewater is mostly used in agriculture. Therefore, the use of wastewater with poor quality characteristics can endanger health. In this study, the neural network model's efficiency was investigated to predict the performance of the Perkandabad wastewater treatment plant in Mashhad in Iran. To achieve this, first, the factors affecting the TBOD parameter were identified as one of the quality indicators of the effluent. In the next step, using a genetic algorithm and network input factors, the performance of the treatment plant was predicted and evaluated. The highest correlation coefficient for the TBOD parameter was 0.89%. The results show that among the input parameters in the model, the amount of organic matter pollution load has the greatest effect on this prediction.
The construction of large-scale infrastructure projects like dams can substantially alter local hydrological systems, prompting concerns about their impacts on river water levels and discharge. This ...study was undertaken in response to the compelling need to investigate and analyze the potential implications of water scarcity, particularly within the framework of the Bisalpur Dam located on the Banas River. This study uses non-parametric trend analysis tests - Mann-Kendall (MK) and Modified Mann-Kendall (MMK) for river discharge and water level trend analysis, and Sen's Slope and Pettit's test for detecting changes or trends. Significant shifts in these parameters were identified post-construction. From 1960 to 2011, the Dam's construction led to a marked decrease in peak discharge (MK/MMK statistics Zc = −3.24; Pc = 0.001), with a Sen's slope of −21.51 MCM/year. Before the Dam's construction, the peak discharge reached a maximum of 7680 MCM in 1981–82. The gauge station's water level significantly decreased (MK/MMK statistics Zc = −3.46; Pc = 0.001) at an annual rate of −0.035 m/year. This level, peaking at 201.59 m in 1981–82, declined from an average of 196.04 m–194.5 m post-construction. The findings underscore the extensive impact of dam construction on local hydrological parameters. These results hold significant implications for future infrastructure projects, emphasizing the critical need for comprehensive environmental impact assessments to be conducted before project implementation. This understanding can aid in designing interventions with reduced environmental impacts, leading to more sustainable infrastructure development.
•After building the Bisalpur Dam, peak discharge decreased significantly.•Before the Dam's construction, the peak discharge reached a maximum of 7680 MCM in the 1981-82.•The water level at the gauge station significantly decreased, declining at an annual rate of −0.035 m/year.
Intensive agricultural practices lead to a deterioration in soil quality, causing a decline in farm productivity and quality, and disturbing the ecosystem balance in command areas. To achieve ...sustainable production and implement effective soil management strategies, understanding the state and spatial variability of soil quality is essential. The study aims to enhance the understanding of soil quality variability and provide actionable insights for sustainable soil management. In this regard, principal component analysis (PCA) and digital soil mapping were used to assess and map the spatial variability of the soil quality index (SQI) in the Cauvery command area, Mandya district, Karnataka, India. A total of 145 georeferenced soil samples were drawn at 0–15 cm depth and analyzed for physico-chemical properties. PCA was used to reduce the dataset into a minimum dataset as eight important soil indicators and to determine relative weightage factors, which were used for assessing SQI with linear and non-linear scoring methods. For spatial assessment of SQI, the random forest algorithm with environmental covariates was used to map eight soil indicators selected in the minimum dataset. The soil property maps were subjected to linear and non-linear scoring, followed by multiplying with corresponding weightage factors and summation to produce SQI maps. Results reveal that values of SQI calculated using linear scoring, range from 0.10 to 0.64, with a mean of 0.39, while non-linear scoring exhibits a wider range of 0.12 to 0.78 and a mean of 0.48. With a slight higher sensitivity index of 6.5, non-linear scoring proved to be the better scoring method compared to linear scoring. Spatial assessment shows that the R2 and LCC between the calculated and predicted SQI were higher for non-linear scoring (0.66 and 0.66) compared to linear scoring (0.60 and 0.65). The SQI maps reveal high spatial variability with more than 40 percent of soils classified as moderate-to-low index. The soils with low SQI were distributed in eastern parts, whereas western parts exhibited high-to-very-high soil quality. To achieve production goals and improve soil quality in the eastern region, sustainable soil and crop management strategies must be developed, and their effects on soil quality should be assessed.
(1) Background: Radon concentrations in the environment are generally very low. However, radon concentrations can be high indoors and can cause some serious health issues. The main source of indoor ...radon (homes, buildings and other residential objects) can be soil under the house, while other sources can be construction materials, groundwater and natural gas. Radon accumulates mainly in the lower levels of the buildings (especially low-ventilated underground levels and basements). (2) Methods: in this paper, we have measured the indoor radon concentrations at 15 locations in various objects (basements and ground floor/1st floor rooms) in the area of northern Croatia. (3) Results: the results show a higher concentration of radon in the basement area in comparison to values measured in the ground floor and first-floor rooms. The arithmetic mean (AM) and geometric mean (GM) of basement rooms were 70.9 ± 38.8 Bq/m3 and 61.2 ± 2.2 Bq/m3 compared to ground floor and first-floor rooms 42.5 ± 30.8 Bq/m3 and 32.8 ± 2.9 Bq/m3, respectively. (4) Conclusions: results obtained (AM and GM values) are within the maximal allowed values (300 Bq/m3) according to the Euroatom Directive. However, there are periods when maximum radon concentration exceeds 300 Bq/m3. Indoor radon concentrations vary with the occupancy of the rooms and it is evident that the ventilation has significant effect on the reduction of concentration.
Because textile industries are intensely water-consuming and generate a huge quantity of wastewater, the present study examines the scope of using solar thermal technology to treat wastewater from ...textile industries. A hybrid technology, comprising a compound parabolic concentrator-based solar thermal system in conjunction with a Membrane Distillation (MD) system, is experimented with for wastewater treatment in textile industries. The MD system requires a water temperature of around 90 °C for efficient functioning. The advanced MD technology using waste heat combined with solar heat to meet the system’s thermal load is technologically evaluated for an experimental textile industry in India. Moreover, the present study critically analyses the techno economics of the proposed hybrid technology. A detailed financial analysis has revealed that, besides technological superiority, the recommended technology is also financially rewarding for wastewater treatment in the textile industry. To cope with the delayed payback period, financial incentives are recommended so that the system becomes a lucrative technological option.
To describe the behaviour of watercourses, numerous parameters should be considered, such as water flow, depth/water level, velocity, and the amount of deposit in a waterbed. In addition, many other ...parameters should be analysed to understand the mechanism of specific watercourses. The most typical parameters are those associated with water quality, such as water temperature, and pH value, and temperature, as well as various climate parameters, such as precipitation, evaporation, and insolation, which are visualised in the form of a time series. The measurement frequency can differ for each parameter. Depending on the number of available measurements, hourly, daily, monthly, and yearly data can be obtained, which can then be used to form a time series. Many well-established and applicable procedures and models for time-series analyses exist, including the rescaled adjusted partial sums method (RAPS). This method is devised to detect possible irregularities and/or fluctuations within the original time series, which cannot be achieved using typical time-series analysis methods. This paper presents a comprehensive review of the application of the RAPS method in hydrology, where the advantages and disadvantages of the method are discussed.
Recikliranje otpadne gume devulkanizacijom Ptiček Siročić, Anita; Florijanić, Franjo; Šokman, Maja ...
Kemija u industriji,
06/2019, Letnik:
68, Številka:
5-6
Journal Article, Paper
Recenzirano
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Posljednjih nekoliko desetljeća polimeri i polimerni materijali postali su neizostavni dio različitih grana industrije i svakodnevnog života. Zbog vrlo raširene upotrebe elastomera nastaju velike ...količine gumenog otpada, što je opterećenje za okoliš te zahtijeva posebne mjere zbrinjavanja kako bi se smanjio njihov negativan utjecaj na okoliš. Uzorci polimernih mješavina na bazi prirodnog (NR) i stiren-butadienskog kaučuka (SBR) pripremljeni su u dvije serije s ciljem ispitivanja mehaničkih (prekidna čvrstoća, prekidno istezanje, ispitivanje čvrstoće na zarez) i reoloških svojstava te krajnje upotrebe u proizvodnji gumenih pružnih prijelaza. Prva serija uzoraka pripremljena je s gumenim prahom, a u drugu seriju umiješan je devulkanizirani gumeni prah. Uzorci su miješani na laboratorijskom mikseru te homogenizirani na laboratorijskom dvovaljku, a proces prešanja proveden je na hidrauličkoj preši. Dobiveni rezultati ispitivanja mehaničkih i reoloških svojstava pokazali su da je za NR/SBR polimernu mješavinu koja bi se upotrebljavala za pružne prijelaze znatno bolja opcija dodatak gumenog praha koji je dodatno devulkaniziran.
Environmental protection requires constant improvement of quality and the environmental management system in accordance with the international standards and laws in order to reduce human impact on the environment and responsibly manage natural resources. Environmentally acceptable recycling of waste tires and other rubber products is one of the biggest ecological challenges today. Landfilling or dumping of tires causes serious long-term pollution. The lack of alternatives for tire recycling increases their disposal in landfills. Recycling is currently the most effective way to improve the sustainability of the environment. The purpose of this work was to determine the optimal composition of the rubber blend to be used for rubber track crossings production, and to examine the ratio of individual components,
i.e.
, milled recycled tires, and milled and devulcanized tires in order to determine which option is more environmentally friendly and financially viable. In the first series of samples, recycled rubber powder (milled recycled tires) was mixed with a polymer blend of natural rubber and styrene-butadiene rubber, while the second series was milled and the devulcanized tires mixed with natural rubber and styrene-butadiene rubber. Rheological and mechanical properties of all the samples were measured according to appropriate standards. The results showed that an increase in the ratio of rubber powder increased the values of minimal rotation resistance and proportionally reduced the maximum rotation resistance. Minor deviations in the values of the vulcanization rate indicated that various ratios of added rubber powder had no significant effect on the rate of vulcanization of individual samples. The results of the viscosity measurement indicated a proportional increase in the values of initial rotation resistance with the increase in the ratio of added rubber dust compared to the samples prepared with milled and devulcanized rubber, whereby a proportional decrease in value was apparent. From the results of mechanical properties, observed was a reduction in tensile strength and elongation at break values for both series of tested samples. The same behaviour was also observed for the tear strength values. With the addition of different filler ratios, the hardness value for both series of prepared samples had reduced, while the values of the rebound elasticity differed slightly. Significant reduction in hardness value was evident for the samples prepared with the milled and devulcanized rubber powder, which could be attributed to the use of a softener during devulcanization of the material. It can be concluded that NR/SBR polymer blends can be mixed with various recycled rubber materials whereby the devulcanization process enables better mechanical and rheological properties, thus, used rubber tires can be effectively removed from the environment.
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