Journal articles: 'Energetic analysis at the national grid level'

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Duan, Chenghua, Chun Liu, Cheng Wang, and Xingye Yue. "Numerical complete solution for random genetic drift by energetic variational approach." ESAIM: Mathematical Modelling and Numerical Analysis 53, no. 2 (March 2019): 615–34. http://dx.doi.org/10.1051/m2an/2018058.

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In this paper, we focus on numerical solutions for random genetic drift problem, which is governed by a degenerated convection-dominated parabolic equation. Due to the fixation phenomenon of genes, Dirac delta singularities will develop at boundary points as time evolves. Based on an energetic variational approach (EnVarA), a balance between the maximal dissipation principle (MDP) and least action principle (LAP), we obtain the trajectory equation. In turn, a numerical scheme is proposed using a convex splitting technique, with the unique solvability (on a convex set) and the energy decay property (in time) justified at a theoretical level. Numerical examples are presented for cases of pure drift and drift with semi-selection. The remarkable advantage of this method is its ability to catch the Dirac delta singularity close to machine precision over any equidistant grid.

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Quintino, Filipe M., Nuno Nascimento, and Edgar C. Fernandes. "Aspects of Hydrogen and Biomethane Introduction in Natural Gas Infrastructure and Equipment." Hydrogen 2, no. 3 (August 10, 2021): 301–18. http://dx.doi.org/10.3390/hydrogen2030016.

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The injection of green hydrogen and biomethane is currently seen as the next step towards the decarbonization of the gas sector in several countries. However, the introduction of these gases in existent infrastructure has energetic, material and operational implications that should be carefully looked at. With regard to a fully blown green gas grid, transport and distribution will require adaptations. Furthermore, the adequate performance of end-use equipment connected to the grid must be accounted for. In this paper, a technical analysis of the energetic, material and operational aspects of hydrogen and biomethane introduction in natural gas infrastructure is performed. Impacts on gas transmission and distribution are evaluated and an interchangeability analysis, supported by one-dimensional Cantera simulations, is conducted. Existing gas infrastructure seems to be generally fit for the introduction of hydrogen and biomethane. Hydrogen content up to 20% by volume appears to be possible to accommodate in current infrastructure with only minor technical modifications. However, at the Distribution System Operator (DSO) level, the introduction of gas quality tracking systems will be required due to the distributed injection nature of hydrogen and biomethane. The different tolerances for hydrogen blending of consumers, depending on end-use equipment, may be critical during the transition period to a 100% green gas grid as there is a risk of pushing consumers off the grid.

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Rossitti, Marco, Marta Dell’Ovo, Alessandra Oppio, and Francesca Torrieri. "The Italian National Strategy for Inner Areas (SNAI): A Critical Analysis of the Indicator Grid." Sustainability 13, no. 12 (June 19, 2021): 6927. http://dx.doi.org/10.3390/su13126927.

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The National Strategy for Inner Areas (SNAI) is a public policy designed to tackle depopulation in inner areas, defined according to the distance from centers offering essential services. Such a policy’s success is crucial to address the new challenges for planning brought to light by the COVID-19 pandemic. In this sense, there is a need to adequately support its implementation by providing handy decision support tools, understanding the power balances among municipalities, and defining proper interventions. The Indicator Grid, already used by the SNAI for project areas selection, can answer this need. However, the Grid’s application to support public policy at the municipality level requires reviewing some of its features, such as the indicators’ large number and the impossibility of defining some of them at the municipal scale. Based on these premises, this paper aims at supporting inner areas policies by carrying out a critical analysis of the current SNAI Grid, aimed at improving its effectiveness. It relies on a hybrid methodology that merges qualitative data interpretations and statistical analyses. Thanks to this method, defining a parsimonious Grid by leaving its complexity and information level untouched is possible. The so-defined set of indicators can represent a valuable reference tool in pinpointing priorities for actions or selecting further territorial scopes from the SNAI perspective, even if it still brings some criticalities to be faced.

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Sun, Xiaoyan, and Wei Wei. "Intravitreal Conbercept with Grid/Focal Photocoagulation for the Treatment of Diabetic Macular Edema: A Systematic Review and Meta-Analysis." Journal of Ophthalmology 2022 (February 24, 2022): 1–9. http://dx.doi.org/10.1155/2022/2256779.

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Diabetic macular edema (DME) is the main cause of blindness in individuals with diabetes mellitus (DM). This meta-analysis compared the effectiveness and safety of macular grid/focal photocoagulation with and without conbercept in the treatment of DME. Studies were identified through systematic searches of PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure database, Wanfang Data Knowledge Service Platform, and VIP Information Resource Integration Service Platform from their earliest records to June 2021. Twelve articles involving 2600 patients with DME were included. Results showed that patients receiving conbercept with macular grid/focal photocoagulation had a statistically significant reduction in central macular thickness (CMT) over macular grid/focal photocoagulation alone at 1 month and 3 months post procedure. Compared with the control group, the combination therapy group had a significantly increased level of effectiveness and best-corrected visual acuity (BCVA) compared with the control group. The combination therapy group significantly increased the level of effectiveness and best-corrected visual acuity (BCVA) compared with the control group. Conbercept with macular grid/focal photocoagulation was more effective than macular grid/focal photocoagulation alone in terms of functional outcomes for DME treatment.

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Jędruch, Michalina, Marek Furmankiewicz, and Iwona Kaczmarek. "Spatial Analysis of Asymmetry in the Development of Tourism Infrastructure in the Borderlands: The Case of the Bystrzyckie and Orlickie Mountains." ISPRS International Journal of Geo-Information 9, no. 8 (July 26, 2020): 470. http://dx.doi.org/10.3390/ijgi9080470.

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This paper discusses the issue of analyzing the development of cross-border tourism infrastructure in the borderlands of countries with diversified administrative divisions and spatial databases, which hinders the use of national statistical units for comparative research. As an example, the ability to use the square grid and kernel density estimation methods for the analysis and spatial visualization of the level of tourism infrastructure development is studied for the Orlickie and Bystrzyckie Mountains, located in the Polish–Czech border area. To synthetically assess and compare the level of diversity, the methodology used in the Human Development Index was adapted using selected component indicators calculated for a square grid clipped to the boundaries of the area under study. This analysis enabled us to quantify the asymmetry in the development of tourism infrastructure in the borderlands via the calculation of the synthetic infrastructure development index. This index is 1.29 times higher in the Czech than in the Polish border area. However, the spatial concentration analysis of infrastructure shows that the diversity in the study area can be assessed as higher than the results using the average density indicators. This paper also discusses the benefits and problems associated with using the square grid method for the representation and analysis of heterogeneous data on tourism infrastructure in two neighboring national states.

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Dr. Sohaib Sultan. "Importance of Pre-Service Teacher Training and Need of Time to Strengthen at National Level." sjesr 3, no. 3 (September 30, 2020): 326–34. http://dx.doi.org/10.36902/sjesr-vol3-iss3-2020(326-334).

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The qualitative research had been carried on to highlight the importance of Pre-Service Teachers, Training programs in the country. It had been observing to underestimate the aforementioned subject during the last decade. For this purpose the topic was selected to carry on research to bring into limelight the importance of pre-service teachers’ training programs in the country. The document analysis was done to highlight the importance in the context of international scenario and its requirement in national grid. The recommendations were furnished accordingly.

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Zhang, Ruixiaoxiao, Meng Ni, Geoffrey Q. P. Shen, and Johnny K. W. Wong. "An analysis on the effectiveness and determinants of the wind power Feed-in-Tariff policy at China’s national-level and regional-grid-level." Sustainable Energy Technologies and Assessments 34 (August 2019): 87–96. http://dx.doi.org/10.1016/j.seta.2019.04.010.

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Sultan, Hamdy, Ahmed Diab, Oleg Kuznetsov, Ziad Ali, and Omer Abdalla. "Evaluation of the Impact of High Penetration Levels of PV Power Plants on the Capacity, Frequency and Voltage Stability of Egypt’s Unified Grid." Energies 12, no. 3 (February 11, 2019): 552. http://dx.doi.org/10.3390/en12030552.

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In this paper, the impact of integrating photovoltaic plants (PVPs) with high penetration levels into the national utility grid of Egypt is demonstrated. Load flow analysis is used to examine the grid capacity in the case of integrating the desired PVPs and computer simulations are also used to assess the upgrading of the transmission network to increase its capacity. Furthermore, the impact of increasing the output power generated from PVPs, during normal conditions, on the static voltage stability was explored. During transient conditions of operation (three-phase short circuit and outage of a large generating station), the impact of high penetration levels of PVPs on the voltage and frequency stability has been presented. Professional DIgSILENT PowerFactory simulation package was used for implementation of all simulation studies. The results of frequency stability analysis proved that the national grid could be maintained stable even when the PVPs reached a penetration level up to 3000 MW of the total generation in Egypt. Transmission network upgrading to accommodate up to 3000 MW from the proposed PV power plants by 2025 is suggested. In addition, analysis of voltage stability manifests that the dynamic behavior of the voltage depends remarkably on the short circuit capacity of the grid at the point of integrating the PVPs.

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Adnan, A. Z., M. E. Yusoff, and H. Hashim. "Analysis on the Impact of Renewable Energy to Power System Fault Level." Indonesian Journal of Electrical Engineering and Computer Science 11, no. 2 (August 1, 2018): 652. http://dx.doi.org/10.11591/ijeecs.v11.i2.pp652-657.

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Distributed Generation is generation of electricity from renewable energy resources, located closer to the customers or loads. Installation of Distributed Generation could improve voltage and power quality, mitigate voltage sags, minimize transmission system congestion, and provide more affordable capacity for utilizing renewable energy resources. However, high penetration of Distributed Generation to the existing national grid system may contribute several impacts including fault level, as well as the performance of power system protection. Monitoring of fault level is important in power system protection in order to sustain the health of power system networks. This paper investigates the impact of installing Distributed Generation to power system fault level. Three-phase symmetrical fault is simulated and analyzed for various sizes of distributed generation in IEEE 30 bus system using Power System Simulation for Engineering (PSS/E) software.<p class="MsoNormal" style="text-align: justify; text-indent: .5in;"><em><span style="font-size: 9.0pt; font-family: 'Arial','sans-serif'; color: black;">Distributed Generation is generation of electricity from renewable energy resources, located closer to the customers or loads. Installation of Distributed Generation could improve voltage and power quality, mitigate voltage sags, minimize transmission system congestion, and provide more affordable capacity for utilizing renewable energy resources. However, high penetration of Distributed Generation to the existing national grid system may contribute several impacts including fault level, as well as the performance of power system protection. Monitoring of fault level is important in power system protection in order to sustain the health of power system networks. This paper investigates the impact of installing Distributed Generation to power system fault level. Three-phase symmetrical fault is simulated and analyzed for various sizes of distributed generation in IEEE 30 bus system using Power System Simulation for Engineering (PSS/E) software.</span></em></p>

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Ren, Guizhou, Fangqing Li, Gang Liu, JianXin Ren, Yudong Liu, and Honghong Shen. "Study on the Development and Utilization of Renewable Energy in China." E3S Web of Conferences 136 (2019): 02013. http://dx.doi.org/10.1051/e3sconf/201913602013.

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With the continuous consumption of fossil energy and non-renewable, countries all over the world pay more and more attention to the use of renewable energy, among which Denmark, Japan, Germany and so on are among the best. Based on the basic national conditions and the energy development situation of our country, the utilization of renewable energy in our country is also promoted to the national strategic position. Experience shows that large-scale renewable energy access to the power grid system can not only meet the electricity demand of industrialized countries. Moreover, the safe and stable operation of the power grid can be realized by advanced technical means. Through the analysis of some advanced technology and equipment research in the development and utilization of renewable energy in foreign power grid, in order to improve the repeatability of our country, The level of development and utilization of raw energy.

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Forouli, Aikaterini, Emmanouil A. Bakirtzis, Georgios Papazoglou, Konstantinos Oureilidis, Vasileios Gkountis, Luisa Candido, Eloi Delgado Ferrer, and Pandelis Biskas. "Assessment of Demand Side Flexibility in European Electricity Markets: A Country Level Review." Energies 14, no. 8 (April 20, 2021): 2324. http://dx.doi.org/10.3390/en14082324.

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Power systems in many countries have recently undergone a significant transition towards renewable and carbon-free generation sources. Those sources pose new challenges to the grid operation due to their intermittency and uncertainty. Consequently, advanced policy strategies and technologies offering new flexibility solutions on the inelastic demand side are required to maintain the reliability of power systems. Given the diversity of situations, legislation and needs across European countries and the varying nature of distribution system operators, this article reviews the deployment of demand side flexibility at national level to identify best practices and main barriers. The analysis concerns European countries of different progress in solutions that leverage flexibility towards offering electricity grid services. The scope is to explore the operation principles of European electricity markets, to assess the participation of emerging flexible resources, and to propose new approaches that facilitate the integration of flexible assets in the distribution grid. The countries reviewed are the United Kingdom, Belgium, Italy and Greece. These countries were selected owing to their diversity in terms of generation mix and market design. Barriers for market access of flexibility resources are also identified in order to form relevant country-specific recommendations.

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Lim, Keumju, Justine Jihyun Kim, and Jongsu Lee. "Forecasting the future scale of vehicle to grid technology for electric vehicles and its economic value as future electric energy source: The case of South Korea." Energy & Environment 31, no. 8 (January 7, 2020): 1350–66. http://dx.doi.org/10.1177/0958305x19898283.

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With the world seeking ways to cope with climate change, the interest in and demand for electric vehicles are increasing as part of the efforts to resolve the issue of fine dust, especially in South Korea. The Korean government has consistently announced plans to promote electric vehicles as a means of transportation by providing benefits such as subsidies for electric vehicle purchase and expansion of charging infrastructure. Meanwhile, as electric vehicles continue to grow in number, the energy industry has become attentive to its role as a resource for power generation through vehicle to grid technology. This study analyzes electric vehicle consumer preferences using the discrete choice experiment (DCE) and found that there exists a clear nested structure in Korean consumers’ choice of vehicle. The study also estimates the amount of vehicle to grid electricity supply in the power market and calculates not only national but also individual economic benefit of electric vehicle owners participating in vehicle to grid services based on the estimated amount of electricity supplied. The results of scenario analysis indicate that the estimated electric vehicle supply in Korea will be about 560,000 units cumulatively and that the vehicle to grid electric vehicle power supply scale will reach 1.81 GW by 2030. The estimation shows that the economic benefit of vehicle to grid at the national power market level is 50.9 billion KRW per year, while the economic benefit at an individual level (per vehicle) is 104,151 KRW.

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MacAfee, Allan W., and Samuel W. K. Wong. "Extreme Value Analysis of Tropical Cyclone Trapped-Fetch Waves." Journal of Applied Meteorology and Climatology 46, no. 10 (October 1, 2007): 1501–22. http://dx.doi.org/10.1175/jam2555.1.

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Abstract Many of the extreme ocean wave events generated by tropical cyclones (TCs) can be explained by examining one component of the spectral wave field, the trapped-fetch wave (TFW). Using a Lagrangian TFW model, a parametric model representation of the local TC wind fields, and the National Hurricane Center’s hurricane database archive, a dataset of TFWs was created from all TCs in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea from 1851 to 2005. The wave height at each hourly position along a TFW trajectory was sorted into 2° × 2° latitude–longitude grid squares. Five grid squares (north of Hispaniola, Gulf of Mexico, Carolina coast, south of Nova Scotia, and south of Newfoundland) were used to determine if extreme value theory could be applied to the extremes in the TFW dataset. The statistical results justify accepting that a generalized Pareto distribution (GPD) model with a threshold of 6 m could be fitted to the data: the datasets were mostly modeled adequately, and much of the output information was useful. Additional tests were performed by sorting the TFW data into the marine areas in Atlantic Canada, which are of particular interest to the Meteorological Service of Canada because of the high ocean traffic, offshore drilling activities, and commercial fishery. GPD models were fitted, and return periods and the 95% confidence intervals (CIs) for 10-, 15-, and 20-m return levels were computed. The results further justified the use of the GPD model; hence, extension to the remaining grid squares was warranted. Of the 607 grid squares successfully modeled, the percentage of grid squares with finite lower (upper) values for the 10-, 15-, and 20-m return level CIs were 100 (80), 94 (53), and 90 (16), respectively. The lower success rate of 20-m TFW CIs was expected, given the rarity of 20-m TFWs: of the 5 713 625 hourly TFW points, only 13 958, or 0.24%, were 20 m or higher. Overall, the distribution of the successfully modeled grid squares in the data domain agreed with TFW theory and TC climatology. As a direct result of this study, the summary datasets and return level plots were integrated into application software for use by risk managers. A description of the applications illustrates their use in addressing various questions on extreme TFWs.

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Ree, Jason Jihoon, and Kwangsoo Kim. "Smart Grid R&D Planning Based on Patent Analysis." Sustainability 11, no. 10 (May 22, 2019): 2907. http://dx.doi.org/10.3390/su11102907.

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A smart grid employs information and communications technology to improve the efficiency, reliability, economics, and sustainability of electricity production and distribution. The convergent and complex nature of a smart grid and the multifarious connection between its individual technology components, as well as competition between private companies, which will exert substantial influences on the future smart grid business, make a strategic approach necessary from the beginning of research and development (R&D) planning with collaborations among various research groups and from national, industry, company, and detailed technological levels. However, the strategic, technological, business environmental, and regulatory barriers between various stakeholders with collaborative or sometimes conflictive interests need to be clarified for a breakthrough in the smart grid field. A strategic R&D planning process was developed in this study to accomplish the complicated tasks, which comprises five steps: (i) background research of smart grid industry; (ii) selection of R&D target; (iii) societal, technological, economical, environmental, and political (STEEP) analysis to obtain a macro-level perspective and insight for achieving the selected R&D target; (iv) patent analysis to explore capabilities of the R&D target and to select the entry direction for smart grid industry; and, (v) nine windows and scenario planning analyses to develop a method and process in establishing a future strategic R&D plan. This R&D planning process was further applied to the case of a Korean company holding technological capabilities in the sustainable smart grid domain, as well as in the sustainable electric vehicle charging system, a global consumer market of smart grid. Four plausible scenarios were produced by varying key change agents for the results of this process, such as technology and growth rates, policies and government subsidies, and system standards of the smart grid charging system: Scenario 1, ‘The Stabilized Settlement of the Smart Grid Industry’; Scenario 2, ‘The Short-lived Blue Ocean of the Smart Grid Industry’; Scenario 3, ‘The Questionable Market of the Smart Grid’; and, Scenario 4, ‘The Stalemate of the Smart Grid Industry’. The R&D plan suggestions were arranged for each scenario and detailed ways to cope with dissonant situations were also implied for the company. In sum, in this case study, a future strategic R&D plan was suggested in regard to the electric vehicle charging technology business, which includes smart grid communication system, battery charging duration, service infrastructure, public charge station system, platform and module, wireless charging, data management system, and electric system solution. The strategic R&D planning process of this study can be applicable in various technologies and business fields, because of no inherent dependency on particular subject, like electric vehicle charging technology based on smart grid.

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Ostojski, Arkadiusz. "Elementary analysis and energetic potential of the municipal sewage sludges from the Gdańsk and Kościerzyna WWTPs." E3S Web of Conferences 26 (2018): 00004. http://dx.doi.org/10.1051/e3sconf/20182600004.

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This paper aims to present municipal sewage sludge (MSS) elementary analysis and energetic potential based on measurement of heat of combustion (higher heating value HHV) and calculation of calorific values (lower heating value LHV). The analysis takes into the consideration water content in sewage sludge, at different utilization stages, in wastewater treatment plants in Gdańsk Wschód and Kościerzyna – Pomeranian Voivodeship. The study yielded the following results (in % dry matter): ash 19÷31 %, C - 31÷36 %, H - 5÷6 %, N - 4÷6 %, O - 28÷32 %, S – 1 %. Calorific value of stabilized sludges in Gdańsk was on average 13.8÷15 MJ/kg. In case of sludges not undergoing digestion from Kościerzyna WWTP, the calorific value was at the level of 17.5 MJ/kg. Thus, sewage sludges are good energy carriers. High water content though is the problem, as it lowers the useful effect of heat. There is no alternative for thermal sewage sludge neutralization, which is in conformity with valid Polish National Waste Management Plan (KPGO 2022).

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Tomczewski, Andrzej. "Operation of a Wind Turbine-Flywheel Energy Storage System under Conditions of Stochastic Change of Wind Energy." Scientific World Journal 2014 (2014): 1–16. http://dx.doi.org/10.1155/2014/643769.

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The paper presents the issues of a wind turbine-flywheel energy storage system (WT-FESS) operation under real conditions. Stochastic changes of wind energy in time cause significant fluctuations of the system output power and as a result have a negative impact on the quality of the generated electrical energy. In the author’s opinion it is possible to reduce the aforementioned effects by using an energy storage of an appropriate type and capacity. It was assumed that based on the technical parameters of a wind turbine-energy storage system and its geographical location one can determine the boundary capacity of the storage, which helps prevent power cuts to the grid at the assumed probability. Flywheel energy storage was selected due to its characteristics and technical parameters. The storage capacity was determined based on an empirical relationship using the results of the proposed statistical and energetic analysis of the measured wind velocity courses. A detailed algorithm of the WT-FESS with the power grid system was developed, eliminating short-term breaks in the turbine operation and periods when the wind turbine power was below the assumed level.

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Pliuhin, Vladyslav, and Vitaliy Teterev. "Possibility Implementation Analysis of the Smart Grid Network in a Current State Conditions of the United Energy Systems of Ukraine." Lighting engineering and power engineering 60, no. 1 (April 30, 2021): 15–22. http://dx.doi.org/10.33042/2079-424x.2021.60.1.03.

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The paper analyzes the current state of the energy system of Ukraine and the efficiency of generation and transmission of electricity. The analysis of the best world practices shows that the active development of modern technologies of energy accounting allows: to bring to a fundamentally new level the quality of data collection and analysis of consumers’ energy consumption; increases the efficiency of operational management of energy assets; promotes the active involvement of energy consumers in the processes of regulating their own energy consumption. Ukraine's energy system has been in operation for quite a long time, and it is difficult for it to withstand the load of modern times. The high level of wear of the main and auxiliary equipment of the power system and the uneven distribution of load in the network often lead to emergencies and power outages to consumers. Undoubtedly, increasing the efficiency of electricitygeneration and supply is an important and urgent task for Ukraine's energy sector. One of the modern and innovative concepts that can significantly affect the quality of electricity transmission is Smart Grid technology. This technology and its capabilities are not new. But the problems that accompany the widespread introduction of Smart Grid in the energy market of Ukraine do not have an unambiguous and effective solution. In this regard, this paper proposes to consider and discuss several scenarios for the implementation of Smart Grid in Ukraine, with an overview of their advantages and disadvantages. In particular, this is a scenario of monitoring and point-by-point implementation of certain Smart Grid technologies; scenario of development of existing and creation of new competencies in the field of Smart Grid; scenario of development and re-implementation of a comprehensive national program of innovative development of electric power on the basis of the Smart Grid concept. The ways of mathematical formulation of the Smart Grid optimization problem using the Data Science approach based on the machine learning system and neural networks are determined separately. These include Big Data processing methods, Data Mining, statistical methods, artificial intelligence methods, and Machine Learning. Data Science includes methods of designing and developing databases and application software. The main practical purpose of the scientist's work is to extract useful information for business from large arrays of information, identify patterns, develop and test hypotheses by modeling and developing new software, and therefore are necessary and sufficient conditions for theoretical justification of practical implementation of Smart Grid in Ukraine.

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Pati, Sutapa. "Socio-Technical Drivers for Community Renewable Energy Systems – Analysis of Case Studies from India." Journal of Sustainable Development 10, no. 3 (May 31, 2017): 143. http://dx.doi.org/10.5539/jsd.v10n3p143.

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Renewable energy sector of India has the potential to be a credible alternative for households and communities. The sector accounts for approximately 13 per cent of the national energy capacity, including technologies such as solar grid/ off – grid generation, wind power, small hydro power, biomass/ biogas, and waste to energy. Statistics related to implementation illustrate the scope of tapping the renewable energy sector comprehensively, esp. for decentralized, household and community level applications. This paper analyses on – ground case studies and projects from various renewable energy categories, specifically the socio – technical and community aspects that play a significant role in successful Renewable Energy Technologies (henceforth RET) implementation. The distilled positive and negative drivers include technical, economic considerations, policy and regulatory, environmental aspects, market/ business models, and social/ community linked aspects. Case studies describe the need for a system based and stakeholder engagement approach where all possible stakeholders and their issues are envisaged and taken into account. Use of an evaluating framework is suggested to ensure successful community models of RETs and mass adoption of renewable technologies.

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Murariu, Alin Constantin. "Investigations of Failure Mechanism and Structural Integrity of a Hydro-Energetic Component." Advanced Materials Research 1146 (April 2018): 1–8. http://dx.doi.org/10.4028/www.scientific.net/amr.1146.1.

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Hydro-energetic equipment and installations are part of a national energy system. Age and their wear, lack of implementation of the risk-based inspections on the structural integrity of components and a proper risk management system can lead to unexpected in-service failure, which causes temporary disturbances in electricity distribution networks and financial losses. Paper presents the structural integrity analysis of the cause of failure of a spindle from a hydro-aggregate. For the material characterization, tensile tests, notch impact tests, hardness tests and non-destructive visual and magnetic particle tests (NDT) were performed. The experimental program also includes complementary investigation for chemical and structural analysis using Energy-Dispersive X-ray spectroscopy (EDX) and Scanning Electron Microscopy (SEM) techniques to assess the quantity and dispersion of elements in different areas of the fractured surface to highlight the particularities of material degradation. Connecting the inspections results leads to an in-depth understanding of the components failure mechanisms, which allows increasing the safety level in operation of the installations by adopting specific measures for avoidance of similar failure. From analysis and experimental results of this study, overload by shock in operation, particularly low steel toughness and non-metallic aligned or clustered inclusions are shown to be the main reason of spindle failure.

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Jačková, Kateřina, and Dušan Romportl. "The Relationship Between Geodiversity and Habitat Richness in Šumava National Park and Křivoklátsko PLA (Czech Republic): A Quantitative Analysis Approach." Journal of Landscape Ecology 1, no. 1 (January 1, 2008): 23–38. http://dx.doi.org/10.2478/v10285-012-0003-6.

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The Relationship Between Geodiversity and Habitat Richness in Šumava National Park and Křivoklátsko PLA (Czech Republic): A Quantitative Analysis Approach This paper focuses on the development of a quantitative method for evaluating the relationship between abiotic heterogeneity and habitat richness at the landscape level. The study took place in the Křivoklátsko protected landscape area and Šumava national park (Czech Republic). Our initial hypothesis was that habitat richness should be high in areas with high abiotic heterogeneity, and vice versa. GIS vector layers of habitat were used for the formulation of habitat richness. A geological layer, a digital terrain model and hydrographic layers were used to determine abiotic heterogeneity. The study areas were overlain by a grid square and habitat richness and abiotic heterogeneity were assessed in each study cell. The data obtained were used in a statistical model (multiple spatial linear regression, with maximum credibility). The results of the statistical model indicated a significant influence of abiotic heterogeneity on habitat richness.

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Koo, Kang-Min, Kuk-Heon Han, Kyung-Soo Jun, Gyumin Lee, and Kyung-Taek Yum. "Smart Water Grid Research Group Project: An Introduction to the Smart Water Grid Living-Lab Demonstrative Operation in YeongJong Island, Korea." Sustainability 13, no. 9 (May 10, 2021): 5325. http://dx.doi.org/10.3390/su13095325.

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In South Korea, in line with the increasing need for a reliable water supply following the continuous increase in water demand, the Smart Water Grid Research Group (SWGRG) was officially launched in 2012. With the vision of providing water welfare at a national level, SWGRG incorporated Information and Communications Technology in its water resource management, and built a living lab for the demonstrative operation of the Smart Water Grid (SWG). The living lab was built in Block 112 of YeongJong Island, Incheon, South Korea (area of 17.4 km2, population of 8000), where Incheon International Airport, a hub for Northeast Asia, is located. In this location, water is supplied through a single submarine pipeline, making the location optimal for responses to water crises and the construction of a water supply system during emergencies. From 2017 to 2019, ultrasonic wave type smart water meters and IEEE 802.15.4 Advanced Metering Infrastructure (AMI) networks were installed at 527 sites of 958 consumer areas in the living lab. Therefore, this study introduces the development of SWG core element technologies (Intelligent water source management and distribution system, Smart water distribution network planning/control/operation strategy establishment, AMI network and device development, Integrated management of bi-directional smart water information), and operation solutions (Smart water statistics information, Real-time demand-supply analysis, Decision support system, Real-time hydraulic pipeline network analysis, Smart DB management, and Water information mobile application) through a field operation and testing in the living lab.

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Zhang, Fan, Shui Yuan Cheng, Ping Zhong, Rui Wu, Ming Juan Ma, and Wei Wei Gong. "Study of China’s Highway Environmental Monitoring Network Planning." Applied Mechanics and Materials 675-677 (October 2014): 318–24. http://dx.doi.org/10.4028/www.scientific.net/amm.675-677.318.

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Environmental monitoring of national highway is an important content of China’s environmental monitoring network in the transport field, a part of national environmental monitoring system, and also a significant basis for environmental protection supervision and management of the transport industry. Using the methods of spatial analysis, grid analysis, and optimization through ArcGIS, monitoring objects of Chinese national highway environmental monitoring network had been screened out. Among which, the environmental quality monitoring objects are composed of the national highway sensitive sections nearby or passing through 277 natural reserves, 32 national scenic areas, 7 of the world’s natural and cultural heritage sites, 8 important wetlands, 398 important reservoirs, and 193 state-level sensitive aquatic germ plasm resources conservation areas; and the pollutant emission monitoring objects include 316 long and extra-long tunnels, 539 service areas and 601 toll stations with large traffic volume. Environmental quality monitoring objects and pollutant emission monitoring objects form China’s National Highway Environmental Monitoring Network, which has filled the blank of highway environmental monitoring in the national environmental monitoring network. It will play a positive role in promoting the green development of China's transport industry.

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Bimenyimana, Samuel, Chen Wang, Godwin Norense Osarumwense Asemota, Aphrodis Nduwamungu, Cicilia Kemunto Mesa, Jeanne Paula Ihirwe, Jean De Dieu Niyonteze, et al. "A Technoeconomic Feasibility Analysis for Affordable Energy System in the East African Community Countries." International Journal of Photoenergy 2021 (August 23, 2021): 1–19. http://dx.doi.org/10.1155/2021/9921940.

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Access to energy is among the key pillars to socioeconomic and improved life style. The East African Community (EAC) countries, also members of sub-Saharan Africa, are among countries with enough energy resources but still struggling with low electricity access, and the lower proportion of citizens with electricity access challenges such as expensive tariff, frequent blackouts, and unreliable service still persists. Diesel technology is among the easy and fast installation technologies for a location with an urgent need of electricity while solar is a clean technology with free fuel. Considering the diversity of electricity tariffs, cost of diesel fuel, and suitability to solar energy exploitation in EAC, this paper intends to provide a technoeconomic analysis for reliable, affordable, and sustainable energy system in the region. A daily load of 94.44 kWh recorded from averaging electricity bills of a luxury house in Kigali, Rwanda, is used as research object, and HOMER simulations are carried on considering the level of such daily load being supplied by either (a) diesel generator, (b) solar + diesel technology, (c) PV + battery storage, or (d) PV + battery storage + grid system in each member country of the EAC. The results show that (a) solar energy is a feasible and applicable technology for energy generation for the whole six EAC countries; (b) for South Sudan, if it is a standalone system, the diesel technology is less costly than solar technology; however, solar energy can still be recommended to be adopted as it has no gas emissions; (c) except South Sudan, PV + battery storage technology is found to be more affordable and cleaner than any technology including diesel; and (d) the option of connecting PV + battery storage to the grid is found more economical for locations where grid interaction is possible because their levelized electricity costs (LCOE) are lower than the real electricity tariffs currently in use within each of the six EAC countries. The solar energy system with battery storage (both off-grid and grid connected) proposed in this research can lead to an efficient increase of national energy resource exploitation in the EAC countries, resulting in reliable, affordable, and sustainable energy access to all the citizenry of the EAC.

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Ru, Yuanxi, Xi Li, and Wubetu Anley Belay. "Tracking Spatiotemporal Patterns of Rwanda’s Electrification Using Multi-Temporal VIIRS Nighttime Light Imagery." Remote Sensing 14, no. 17 (September 4, 2022): 4397. http://dx.doi.org/10.3390/rs14174397.

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After recovering from the Rwanda Genocide in the last century, Rwanda is experiencing rapid economic growth and urban expansion. With increasing demand for electricity and a strong desire to achieve the Sustainable Development Goals (SDGs), it is significant to further investigate the electrification progress in Rwanda. This study analyzes the characteristics of electrification in Rwanda from 2012 to 2020 using VIIRS nighttime light imagery. Firstly, by analysis of the nighttime light change patterns on a national scale, we find that the electrification in Rwanda is seriously unbalanced, as electrification progress in Kigali is much faster than that in the rest of the country. Secondly, there is a common phenomenon where power grid expansion in Rwanda fails to keep pace with rapid urbanization, especially in areas with an inadequate electricity infrastructure foundation. Quantitatively, original electricity infrastructure level shows a positive impact on the grid access of new settlements, with an R2 value of 0.695 in the linear regression. In addition, new settlements inside the urban boundary tend to achieve more extensive grid access compared to those outside the boundary. Finally, the grid access rates are calculated on multi-spatial scales. By comparing the calculated results with the official electricity access rate data, we analyze the development of off-grid access in Rwanda. The results imply that, since 2016, off-grid access has rapidly developed in Rwanda, especially in the rural areas, playing an important role in achieving the SDGs.

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Mengyao, Lu. "Optimization Analysis on Layout of 220kV Outdoor Substation for Noise Control at the Boundary." E3S Web of Conferences 271 (2021): 01011. http://dx.doi.org/10.1051/e3sconf/202127101011.

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The noise in substations has become one of the most concerning problems in the field of power grid. In this paper, the principle of substation layout optimization based on the maximum acoustic ray shielding method is established in the premise of the sound wave propagation rule in complicated air medium to meet the requirements of relevant national environmental standards for noise at the boundary of the substation. By establishing the acoustic simulation analysis model of the 220kV outdoor substation, the noise level at the boundary of the substation before and after the layout optimization is compared and analysed, and the distribution rule of the sound field inside and outside the substation is obtained. The analysis results show that the optimized layout of the substation can effectively reduce the noise at the boundary of the substation, which provides a control method for the noise optimization design of the substation.

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Ellenson, Ashley, and H. Tuba Özkan-Haller. "Predicting Large Ocean Wave Events Characterized by Bimodal Energy Spectra in the Presence of a Low-Level Southerly Wind Feature." Weather and Forecasting 33, no. 2 (March 19, 2018): 479–99. http://dx.doi.org/10.1175/waf-d-17-0035.1.

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Abstract Three large wave events are simulated with WaveWatch III using different wind inputs and physics packages. The modeled output, including spectral shape and bulk parameter time series, are compared with National Data Buoy Center buoy observations offshore of Newport, Oregon. The atmospheric conditions that generate these large waves include a strong southerly wind along with a distant cyclone. The energetic contributions of these simultaneously occurring atmospheric features result in a wave field characterized by bimodal energy spectra for two events and unimodal energy spectra for the third event. The analysis of model output evaluates bulk parameter time series of significant wave height, mean period, and mean wave direction derived from partitioned energy spectra. A consistent underestimation in wave energy approaching from the southwestern direction is found for the output associated with all model configurations. This wave energy is generated by the southerly wind. An overestimation in swell energy approaching from the northwest is also found for all model configurations. The model configuration that most accurately reproduces the southerly wave energy results in the best performance for the overall bulk parameters.

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Khan, Muhammad Iftikhar, and Muhammad Amir. "Design and Stability Analysis of a proposed Microgrid for on Campus Diesel and Photovoltaic Power Sources." Proceedings of the Pakistan Academy of Sciences: A. Physical and Computational Sciences 58, no. 1 (September 1, 2021): 47–60. http://dx.doi.org/10.53560/ppasa(58-1)723.

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Pakistan is currently facing an energy crisis that is detrimental to its growth. Due to persistent load shedding by the National Grid throughout the country, the latest trend is tilting towards generating power at localized level through a mix of renewable and conventional energy sources. Such a mixture is referred to as Distributed Energy Resource (DER). Part of such a DER (i.e. solar energy) is free as naturally and mostly available in Pakistan having no degradation problem while providing benefit to the locality. The idea of using a Microgrid for our local power needs morphed accordingly. In this paper, a Microgrid design for our local campus i.e. University of Engineering & Technology, Peshawar, KPK is proposed. Our campus generators are not interconnected. Consequently, even while servicing small load periods, all of our campus’s diesel generators run at full capacity at the same time. Such a behavior is uneconomical, unacceptable and the generators run at low efficiency during islanding from the main utility grid. It is seen that behavior as such is endemic throughout Pakistan. Through design and analysis, it is proposed that if a Microgrid of such unconnected resources on campus is formed then during islanding, all generators and our Photovoltaic (PV) systems will economically and efficiently feed their common loads through load sharing. Synchronization, load flow analysis, short circuit analysis, harmonic analysis, transient stability, cost and reliability of our proposed Microgrid is analyzed using ETAP (Electrical Transient Analyzer Program) in this paper.

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Volianyk, Oleksii. "SMART GRID ENERGY CONSERVATION MANAGEMENT BASED ON THE UNIVERSITY'S ENERGY INNOVATION HUB OF KNOWLEDGE." Management 34, no. 2 (January 10, 2022): 90–102. http://dx.doi.org/10.30857/2415-3206.2021.2.8.

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BACKGROUND AND OBJECTIVES. Due to increasing energy costs, as well as strict environmental regulations, there is a growing need for greater resource efficiency, which makes energy-efficient solutions necessary. Thus, the importance of innovations based on technologies designed to save energy, such as the Smart Grid, is increasing. Smart Grid is not just a compilation of smart meters or other electrical devices, it is a series of technologies, a concept of a fully integrated, self-regulating and self-healing power grid, which has a network topology and includes all sources of generation, transmission and distribution, managed by a single network of information and control devices and systems.METHODS. As the main method used was the calculation of the synthetic balance of savings from the use of different types of energy resources by the university after the implementation of the application Smart Grid-energy conservation management on the basis of the university energy-innovation Hub of knowledge.FINDINGS. A mechanism for the implementation of the Smart Grid energy-saving management application on the basis of the university energy-innovation Knowledge Hub is proposed. Smart Grid is designed to provide real-time data on the almost instantaneous balance of energy supply and demand. To ensure grid reliability by reducing peak demands and improving energy efficiency, Smart Grid data management is an affordable and effective tool for data analysis and decision making.CONCLUSION. The results of calculation of the predicted effect of the Smart Grid application implementation for the 4th building of Kyiv National University of Technologies and Design proved that the reduction of installed capacity as a result of the project was 80.5%, i.e. a 1% reduction in capacity creates an economic effect of 0.58% of the costs associated with modernization. Given the current level of electricity consumption, we can predict a potential reduction of 951 thousand UAH per year or almost 50% of the cost of electricity consumed in 2020.

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Deng, Aijun, and David R. Stauffer. "On Improving 4-km Mesoscale Model Simulations." Journal of Applied Meteorology and Climatology 45, no. 3 (March 1, 2006): 361–81. http://dx.doi.org/10.1175/jam2341.1.

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Abstract A previous study showed that use of analysis-nudging four-dimensional data assimilation (FDDA) and improved physics in the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) produced the best overall performance on a 12-km-domain simulation, based on the 18–19 September 1983 Cross-Appalachian Tracer Experiment (CAPTEX) case. However, reducing the simulated grid length to 4 km had detrimental effects. The primary cause was likely the explicit representation of convection accompanying a cold-frontal system. Because no convective parameterization scheme (CPS) was used, the convective updrafts were forced on coarser-than-realistic scales, and the rainfall and the atmospheric response to the convection were too strong. The evaporative cooling and downdrafts were too vigorous, causing widespread disruption of the low-level winds and spurious advection of the simulated tracer. In this study, a series of experiments was designed to address this general problem involving 4-km model precipitation and gridpoint storms and associated model sensitivities to the use of FDDA, planetary boundary layer (PBL) turbulence physics, grid-explicit microphysics, a CPS, and enhanced horizontal diffusion. Some of the conclusions include the following: 1) Enhanced parameterized vertical mixing in the turbulent kinetic energy (TKE) turbulence scheme has shown marked improvements in the simulated fields. 2) Use of a CPS on the 4-km grid improved the precipitation and low-level wind results. 3) Use of the Hong and Pan Medium-Range Forecast PBL scheme showed larger model errors within the PBL and a clear tendency to predict much deeper PBL heights than the TKE scheme. 4) Combining observation-nudging FDDA with a CPS produced the best overall simulations. 5) Finer horizontal resolution does not always produce better simulations, especially in convectively unstable environments, and a new CPS suitable for 4-km resolution is needed. 6) Although use of current CPSs may violate their underlying assumptions related to the size of the convective element relative to the grid size, the gridpoint storm problem was greatly reduced by applying a CPS to the 4-km grid.

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Ahmad, Firoz, and Laxmi Goparaju. "Forest Fire Trend and Influence of Climate Variability in India: A Geospatial Analysis at National and Local Scale." Ekológia (Bratislava) 38, no. 1 (March 1, 2019): 49–68. http://dx.doi.org/10.2478/eko-2019-0005.

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AbstractClimate change and its severity play an important role in forest fire regime. Analysing the forest fires events becomes a prerequisite for safeguarding the forest from further damage. We have made an assessment of the long-term forest fire events at the district level in India and identified the forest fire hotspot districts. The spatial seasonal (January to June) district wise pattern and forest fire trend were analysed. In the second part of the study area (central part of India), we have evaluated the forest fire events in grid format with respect to the climatic/weather datasets, and the statistical analysis Cramer V coefficient (CVC) was performed to understand its association/relationship with forest fire events.The study revealed that Karbi Anglong and North Cachar Hills districts of Assam of India have the highest forest fire percent among all districts equivalent to 3.4 and 3.2% respectively. Dantewada district of Chhattisgarh and Garhchiroli district of Maharashtra of India occupied 3rd and 4th rank with value 3.1 and 3.0% respectively. The grid-based evaluation (local scale) revealed that most of the fire equivalent of 80% was found in the month of March and April. Forest fire frequency of the month of April is spread over 88 % of the grids over the study area. The 11 years average seasonal month-wise (February to June) maximum temperature, wind velocity, relative humidity, and solar radiation were found in the range of (25.9 to 40.6), (1.69 to 2.7), (0.301 to 0.736) and (14.21 to 22.98) respectively. The percentage increase (in the month of March) of maximum temperature, wind velocity, and solar radiation were 36, 39 and 62% respectively, when compared with the preceding month; whereas, a 60% decrease to relative humidity that was observed in the same month is usually the major cause of forest fire events in the month of March onwards.The evaluation of Cramer V coefficient (CVC) values of rainfall, relative humidity, potential evapotranspiration, maximum temperature, wind velocity, and solar radiation were in decreasing order and in the range of 0.778 to 0.293. The highest value of rainfall (0.778) showed its strongest association with the forest fire events. In the month of June, these areas receive adequate rainfall, which leads to an increase in the soil moisture and a reduction in forest fuel burning capacity by absorbing the moisture and it is a strong reason for less forest fire events during this month. Geospatial technology provides an opportunity to evaluate large datasets over various spatial and temporal scales and help in decision making/formulating various policies.

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Javed, Haniya, Arianna Brambilla, and Marcus Strang. "A climate-based moisture index approach for hygrothermal analysis in Australia." Journal of Physics: Conference Series 2069, no. 1 (November 1, 2021): 012065. http://dx.doi.org/10.1088/1742-6596/2069/1/012065.

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Abstract In Australia, one-third of new constructions are affected by condensation and about 50% of buildings suffer from mould risk, mainly due to inappropriate design and management strategies. Despite the potential structural damage and serious health hazards, there is a lack of preventive moisture management strategies at the legislative level. The first hygrothermal management provisions were adopted in the National Construction Code only in 2019, with very general indications that correlate the breathability of the membranes with the climate zone. However, the building code identifies only eight zones for the entire Australia, which were originally developed for thermal analysis and energy efficiency provisions. The result is a coarse climate grid that clusters locations with highly variable humidity conditions. This paper undertakes a semi-empirical approach to identify whether the current climate zones are suitable for hygrothermal purposes. This research represents the first step towards an Australian-specific moisture risks management framework, and it advances the discussion about the suitability of the current hygrothermal design and construction policy and practices. The outcomes reveal the highly variable moisture indices obtained for the different representative cities, affirming the inappropriate use of existing climate zone clustering for hygrothermal assessment purposes.

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Lima, Gabriel Constantino de, Andre Luiz Lopes Toledo, and Leonidas Bourikas. "The Role of National Energy Policies and Life Cycle Emissions of PV Systems in Reducing Global Net Emissions of Greenhouse Gases." Energies 14, no. 4 (February 11, 2021): 961. http://dx.doi.org/10.3390/en14040961.

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The energy sector and electricity generation in particular, is responsible for a great share of the global greenhouse gas (GHG) emissions. World electricity generation is still largely based on the burning of fossil fuels. However, Brazil has already a very low electricity carbon intensity due to the country’s large hydropower capacity. In countries with low grid carbon intensities such as Brazil, the investment in photovoltaic solar systems (PVSS) even if it is cost-effective, might become challenging as any new generation competes essentially against other renewable generation and the carbon offset is not a key driver for investment anymore. This study builds further upon that case to examine if national renewable energy incentives could actually lead to an increase of global net carbon emissions from the installation of PVSS in countries with a low grid carbon intensity. The study presents a life cycle analysis (LCA) of ten photovoltaic systems representative of the different operational conditions in regions across Brazil. It was found that the average energy payback time of the studied PV plants is between 3 and 5 years of operation. This result shows the feasibility and viability of such investments in the Brazilian context. When the LCA was integrated into the analysis though, the results showed that the “local” direct emissions avoidance from two out of ten studied PV plants would not manage to offset their “global” life cycle emissions due to the 2020 projected Brazilian grid emission factor which is already low. It is important to recognize that public policies of unrestricted, unconditional stimulus to photovoltaic systems investment might not help towards reducing global net emissions when the PV systems are installed at countries with a low carbon emission electric matrix. That is also something to consider for other countries as the carbon intensity of their grids will start reducing at levels similar to Brazil’s. It is likely that in the near future, the real net carbon offset achieved by PV systems at the global level will be largely defined by the manufacture procedures and the production’s carbon intensity at the country of origin of the PV panels.

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Gul, Mehr, Nengling Tai, Wentao Huang, Muhammad Haroon Nadeem, Muhammad Ahmad, and Moduo Yu. "Technical and Economic Assessment of VSC-HVDC Transmission Model: A Case Study of South-Western Region in Pakistan." Electronics 8, no. 11 (November 7, 2019): 1305. http://dx.doi.org/10.3390/electronics8111305.

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The southwestern part of Pakistan is still not connected to the national grid, despite its abundance in renewable energy resources. However, this area becomes more important for energy projects due to the development of the deep-sea Gwadar port and the China Pakistan Economic Corridor (CPEC). In this paper, a voltage source converter (VSC) based high voltage DC (HVDC) transmission model is proposed to link this area to the national gird. A two-terminal VSC-HVDC model is used as a case study, in which a two-level converter with standard double-loop control is employed. The proposed model has a capacity of transferring bulk power of 3500 MW at 350 kV from Gwadar to Matiari. Furthermore, the discounted cash flow analysis of VSC-HVDC against the HVAC system shows that the proposed system is economically sustainable. The outcomes of this study reveal that the implementation of this project can bring economic stability and energy security in the southwestern region.

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Ajiwibowo, Harman, and Munawir Bintang Pratama. "Hydrodynamic Model and Tidal Current Energy Potential in Lepar Strait, Indonesia." International Journal of Renewable Energy Development 11, no. 1 (July 30, 2021): 15–25. http://dx.doi.org/10.14710/ijred.2022.37028.

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Previous studies have shown the abundance of tidal energy resources in Indonesia. However, some sites have yet to be considered. The Lepar Strait, for example, is located between Bangka and Lepar Islands. This paper describes a field survey and numerical modelling conducted in the Lepar Strait. The modelling was performed using Delft3D, with the aim of determining potential sites for harvesting tidal current energy and estimate the generated power. In the modelling, the domain decomposition method was employed for model downscaling, allowing grid resolution reaching 130 x 130 m2, which is sufficient to represent the narrow gaps between tiny islands in the area of interest. The National Bathymetric (Batnas) from the Geospatial Information Agency (BIG) and the International Hydrographic Organization (IHO) tide constituents were applied for the bathymetry and tide elevation boundaries. The comparison between the surveyed and modelled data showed a good agreement. The RMSE and r for water level are > 0.95 and < 0.15, and the RMSE for velocity was <0.19. Furthermore, an energetic flow reaching 1.5 m/s was found at the Northern part of Lepar Strait, situated at the narrow gaps. The Gorlov Helical Turbine was selected in this study due to shallow water and low mean velocity. In the 2019 model, the power density and power output at the best potential sites were 2,436.94 kWh/m2 and 1,870.41 kWh, respectively. This number is higher than those previously found in Kelabat Bay. Nonetheless, it is still far below the currently promising project in Larantuka and Lombok Straits. Future research is recommended, to conduct a detailed field measurement campaign and assess the impact of energy extraction in more detail.

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Gebregiorgis, Abebe Sine, Pierre-Emmanuel Kirstetter, Yang E. Hong, Nicholas J. Carr, Jonathan J. Gourley, Walt Petersen, and Yaoyao Zheng. "Understanding Overland Multisensor Satellite Precipitation Error in TMPA-RT Products." Journal of Hydrometeorology 18, no. 2 (January 12, 2017): 285–306. http://dx.doi.org/10.1175/jhm-d-15-0207.1.

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Abstract The Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) has provided the global community a widely used multisatellite (and multisensor type) estimate of quasi-global precipitation. One of the TMPA level-3 products, 3B42RT/TMPA-RT (where RT indicates real time), is a merged product of microwave (MW) and infrared (IR) precipitation estimates, which attempts to exploit the most desirable aspects of both types of sensors, namely, quality rainfall estimation and spatiotemporal resolution. This study extensively and systematically evaluates multisatellite precipitation errors by tracking the sensor-specific error sources and quantifying the biases originating from multiple sensors. High-resolution, ground-based radar precipitation estimates from the Multi-Radar Multi-Sensor (MRMS) system, developed by the National Severe Storms Laboratory (NSSL), are utilized as reference data. The analysis procedure involves segregating the grid precipitation estimate as a function of sensor source, decomposing the bias, and then quantifying the error contribution per grid. The results of this study reveal that while all three aspects of detection (i.e., hit, missed-rain, and false-rain biases) contribute to the total bias associated with IR precipitation estimates, overestimation bias (positive hit bias) and missed precipitation are the dominant error sources for MW precipitation estimates. Considering only MW sensors, the TRMM Microwave Imager (TMI) shows the largest missed-rain and overestimation biases (nearly double that of the other MW estimates) per grid box during the summer and winter seasons. The Special Sensor Microwave Imagers/Sounders (SSMIS on board F17 and F16) also show major error during winter and spring, respectively.

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Hernandez-Escobedo, Quetzalcoatl, Alida Ramirez-Jimenez, Jesús Manuel Dorador-Gonzalez, Miguel-Angel Perea-Moreno, and Alberto-Jesus Perea-Moreno. "Sustainable Solar Energy in Mexican Universities. Case Study: The National School of Higher Studies Juriquilla (UNAM)." Sustainability 12, no. 8 (April 13, 2020): 3123. http://dx.doi.org/10.3390/su12083123.

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Universities around the world should be at the forefront of energy-saving and efficiency processes, seeking to be at the same level or preferably higher than the rest of society, and seeking the goal of 20% renewable energy by 2020. Sustainability practices have been carried out by several universities. In Mexico, the National Autonomous University of Mexico (UNAM) is a leader in this subject; in fact, the newest National School of Higher Studies - Juriquilla (ENES-J) that belongs to UNAM, located in the city of Queretaro (Mexico), is involved in its sustainability plan, with one of its main objectives being to save electric energy. UNAM has some campuses outside of Mexico City, and one of them is the National School of Higher Studies Juriquilla (ENES-J) in the state of Queretaro, where there is the Orthotics and Prosthetics Laboratory (OPL), in which has been installed a Computer Numerical Control (CNC) machine type Haas Automation model UMC-750, which has 5-axis and is an effective means to reduce the number of setups and increase accuracy for multi-sided and complex parts. This machine will be used to design, build, and assess human prosthesis. This study aimed to contribute to sustainability policies at the ENES-J from UNAM, implementing a solar photovoltaic system (PVS) to deliver electricity to the grid and contribute to reducing the electricity load at the Orthotics and Prosthetics Laboratory (OPL), as well to propose new research lines to support the sustainability policies in universities, and also proposing a financial analysis. To achieve this, in an area of 96.7 m2, 50 solar panels type mono-Si Advance Power API-M330 with an efficiency of 17.83% and a capacity factor of 20.4% will be installed and will provide 17.25 kW of power and 345 kWh of energy. The financial analysis shows the initial costs of 46,575 USD/kW, operation and maintenance (O&M) costs (savings) of 569 USD/kW-year, a monthly electricity export rate of 0.10 USD/kWh, electricity exported to the grid of 21.5 MWh, and an electricity export revenue of 2,145 USD. To assess the environmental balance with this PVS at ENES-J, an analysis of greenhouse gases (GHG) is carried out by using the RETScreen software. In this analysis, a GHG emission factor of 0.45 tCO2/MWh was found, as well as a savings of 12,089 USD per year.

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Alshammari, Meshari, and Maeve Duffy. "Feasibility Analysis of a DC Distribution System for a 6 kW Photovoltaic Installation in Ireland." Energies 14, no. 19 (October 1, 2021): 6265. http://dx.doi.org/10.3390/en14196265.

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Recent developments in micro-grids have led to increased interest in DC distribution due to its high efficiency in distributing energy from renewable energy sources to DC loads. This paper seeks to analyse the performance of AC and DC systems in a relatively large-sized 6 kW PV installation to determine the level of improvement in efficiency provided by DC distribution and to identify methods for further improvement. Baseline annual data for the AC system were collected from a live installation on a national school in Inis Oirr, an island off the west coast of Ireland. The results indicate that usage of a DC distribution system has the potential to reduce system losses by up to 50% as well as the ability for an annual saving in grid energy of 5% compared to the existing AC system. Moreover, the analysis reveals that DC outperforms AC distribution more in spring and autumn, when power consumption is comparable to the system production, but there is less impact in summer, when PV production is significantly higher than demand. These findings provide insights into the benefits of future DC distribution systems in individual buildings and in larger-scale micro-grids.

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Li, Chaodong, Zhanbin Li, Mingyi Yang, Bo Ma, and Baiqun Wang. "Grid-Scale Impact of Climate Change and Human Influence on Soil Erosion within East African Highlands (Kagera Basin)." International Journal of Environmental Research and Public Health 18, no. 5 (March 9, 2021): 2775. http://dx.doi.org/10.3390/ijerph18052775.

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Under global climate change and pressure from human activities, soil erosion is becoming a major concern in the quest for regional sustainable development in the Kagera basin (KB). However, few studies in this region have comprehensively considered the impact of climate change and human influence on soil erosion, and the associated processes are unclear. Based on the premise of quantifying climate change, human influence, and soil erosion, this study undertook a neighborhood analysis as the theoretical support, for a grey relation analysis which was conducted to realize the qualitative assessment of the influence of climate change and human activities on soil erosion. The results show that 90.32% of the KB saw climate change as having a greater influence on soil erosion than human influence, with the remaining area 9.68% seeing human influence having a greater impact than climate change, mainly as a result of the effect of rangeland and farmland. The average soil erosion rate of the KB shows a very low level (10.54 t ha−1 yr−1), with rangeland and farmland being the main land use/land cover (LULC) types that see soil loss, followed by forest, wetland, and built-up areas. The climate change trends of the KB show the most dramatic changes in the northeast and southwest, gradually decreasing towards the line crossing from the Birunga National Park (Rwanda) to the Keza district (Tanzania). The human influence intensity (HII) shows a high level in the KB (21.93), where it is higher in the west and lower in the east of the basin.

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Marchand, Lucile, and Mathilde Hérault. "The Implementation of Buen Vivir in Ecuador: An Analysis of the Stakeholders’ Discourses." European Journal of Sustainable Development 8, no. 3 (October 1, 2019): 282. http://dx.doi.org/10.14207/ejsd.2019.v8n3p282.

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Buen vivir is a central notion in Ecuador and was introduced in its Constitution in 2008. On the individual level, this notion describes a multidimensional form of well-being, integrating strong cultural and ecological aspects based on indigenous communities’ knowledge. On the national scale, buen vivir is the key notion of public policies and justifies an intervention of the state in all dimensions of sustainable development. The implementation of buen vivir in a developing country as Ecuador raises questions about multiple social and economic aspects. The aim of this paper is to identify all of these challenges that such a transition implies. To do so, this paper uses a qualitative and multidimensional approach based on 40 semi-directive interviews with stakeholders of the policy implementation of buen vivir. The interview grid was divided into four parts: (i) individual characteristics, (ii) definition and implementation of buen vivir, (iii) the extractivism in Ecuador and (iv) the challenges of the transition between two models of development. The preliminary results identify two major challenges. Firstly, the main challenge is the governance of this major transition and the issue of corruption in Ecuador. Secondly, these interviews show that education is the most central dimension to implement buen vivir correctly. Keywords: Buen vivir, discourse’s analysis, extractivism

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Liu, Yu Jen, Yen Chang Chen, Pei Hsiu Lan, and Tsang Pin Chang. "Power Quality Measurements of a Horizontal Axial Small Wind Turbine." Applied Mechanics and Materials 870 (September 2017): 329–34. http://dx.doi.org/10.4028/www.scientific.net/amm.870.329.

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As small wind turbines are increasingly used, the assessments of power quality may thus become paramount. Unlike the large-scale wind turbines which are optional required to perform power quality measurements during production certification stage; however the power quality measurements are often neglected in small wind turbines since they are not requested on the certain of national grid codes at low-voltage distribution system level. Considering the high penetrations of small wind turbines may be connected to the future urban electric network, the paper performs the power quality on-site measurements of a horizontal axle small wind turbines. The issues may include the discussion of measurement system structure, the description of measurement method, and the analysis of wind turbine power characteristic, voltage/current trends, harmonics and flicker phenomena. The measured data collected in the study will valuable for the further analysis of power systems connected with the small wind turbines.

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Aleksankina, Ksenia, Stefan Reis, Massimo Vieno, and Mathew R. Heal. "Advanced methods for uncertainty assessment and global sensitivity analysis of an Eulerian atmospheric chemistry transport model." Atmospheric Chemistry and Physics 19, no. 5 (March 7, 2019): 2881–98. http://dx.doi.org/10.5194/acp-19-2881-2019.

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Abstract. Atmospheric chemistry transport models (ACTMs) are extensively used to provide scientific support for the development of policies to mitigate the detrimental effects of air pollution on human health and ecosystems. Therefore, it is essential to quantitatively assess the level of model uncertainty and to identify the model input parameters that contribute the most to the uncertainty. For complex process-based models, such as ACTMs, uncertainty and global sensitivity analyses are still challenging and are often limited by computational constraints due to the requirement of a large number of model runs. In this work, we demonstrate an emulator-based approach to uncertainty quantification and variance-based sensitivity analysis for the EMEP4UK model (regional application of the European Monitoring and Evaluation Programme Meteorological Synthesizing Centre-West). A separate Gaussian process emulator was used to estimate model predictions at unsampled points in the space of the uncertain model inputs for every modelled grid cell. The training points for the emulator were chosen using an optimised Latin hypercube sampling design. The uncertainties in surface concentrations of O3, NO2, and PM2.5 were propagated from the uncertainties in the anthropogenic emissions of NOx, SO2, NH3, VOC, and primary PM2.5 reported by the UK National Atmospheric Emissions Inventory. The results of the EMEP4UK uncertainty analysis for the annually averaged model predictions indicate that modelled surface concentrations of O3, NO2, and PM2.5 have the highest level of uncertainty in the grid cells comprising urban areas (up to ±7 %, ±9 %, and ±9 %, respectively). The uncertainty in the surface concentrations of O3 and NO2 were dominated by uncertainties in NOx emissions combined from non-dominant sectors (i.e. all sectors excluding energy production and road transport) and shipping emissions. Additionally, uncertainty in O3 was driven by uncertainty in VOC emissions combined from sectors excluding solvent use. Uncertainties in the modelled PM2.5 concentrations were mainly driven by uncertainties in primary PM2.5 emissions and NH3 emissions from the agricultural sector. Uncertainty and sensitivity analyses were also performed for five selected grid cells for monthly averaged model predictions to illustrate the seasonal change in the magnitude of uncertainty and change in the contribution of different model inputs to the overall uncertainty. Our study demonstrates the viability of a Gaussian process emulator-based approach for uncertainty and global sensitivity analyses, which can be applied to other ACTMs. Conducting these analyses helps to increase the confidence in model predictions. Additionally, the emulators created for these analyses can be used to predict the ACTM response for any other combination of perturbed input emissions within the ranges set for the original Latin hypercube sampling design without the need to rerun the ACTM, thus allowing for fast exploratory assessments at significantly reduced computational costs.

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Missoum, Mohammed, and Larbi Loukarfi. "Investigation of a Solar Polygeneration System for a Multi-Storey Residential Building-Dynamic Simulation and Performance Analysis." International Journal of Renewable Energy Development 10, no. 3 (February 10, 2021): 445–58. http://dx.doi.org/10.14710/ijred.2021.34423.

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In the present study, the performance of a novel configuration of a solar polygeneration system for a multi-family residential building is investigated using dynamic simulation models. The system consists in Building Integrated PhotoVoltaic/Thermal (BIPVT) collectors, a water-to-water reversible heat pump and an adsorption chiller. The solar system will ensure space heating in winter, space cooling in summer and domestic hot water and electricity all over the year for a multi-storey building located in Algiers (Algeria). In the case of insufficient solar energy, the system is equipped with a gas-fired heater for auxiliary heat production, whereas the auxiliary electricity is supplied by the national grid. First, the simulation models of the solar system components and the building were described and developed in TRNSYS environment. Then, an energy-economic model based on the calculation of the primary energy consumption, the primary energy saving, the simple payback period and the electrical and thermal solar fractions, was carried-out. Finally, the system performance in terms of daily, monthly and yearly results was investigated and compared to the performance of a conventional energy system commonly used in Algerian buildings. The simulation results indicate that the solar collectors have the potential to cover more than 56% and 72% of the yearly heat and electricity requirements, respectively. The total primary energy saving achieved by the solar system with respect to the conventional one is 37.1 MWh/y, which represents 39% of the energy consumption of the conventional system. However, the economic feasibility of proposed solar system is difficult to be achieved due to the high initial cost of the solar collectors. Indeed, the obtained simple payback period is 55.40 years. Moreover, a sensitivity analysis has been performed aiming at studying the effect of various technical and economical parameters on the system performance. The analysis shows that the energetic as well as economic performances of the system are strongly influenced by the photovoltaic/thermal filed area, the system cost and the unitary cost of electricity. The system becomes economically profitable when the system cost is 400 €/m² and the electricity cost is 0.12 €/kWh. Additionally, the system performance is better in climate conditions where solar potential and building energy requirements are important.

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Goly, Aneesh, Ramesh S. V. Teegavarapu, and Arpita Mondal. "Development and Evaluation of Statistical Downscaling Models for Monthly Precipitation." Earth Interactions 18, no. 18 (November 1, 2014): 1–28. http://dx.doi.org/10.1175/ei-d-14-0024.1.

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Abstract Several statistical downscaling models have been developed in the past couple of decades to assess the hydrologic impacts of climate change by projecting the station-scale hydrological variables from large-scale atmospheric variables simulated by general circulation models (GCMs). This paper presents and compares different statistical downscaling models that use multiple linear regression (MLR), positive coefficient regression (PCR), stepwise regression (SR), and support vector machine (SVM) techniques for estimating monthly rainfall amounts in the state of Florida. Mean sea level pressure, air temperature, geopotential height, specific humidity, U wind, and V wind are used as the explanatory variables/predictors in the downscaling models. Data for these variables are obtained from the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis dataset and the Canadian Centre for Climate Modelling and Analysis (CCCma) Coupled Global Climate Model, version 3 (CGCM3) GCM simulations. The principal component analysis (PCA) and fuzzy c-means clustering method (FCM) are used as part of downscaling model to reduce the dimensionality of the dataset and identify the clusters in the data, respectively. Evaluation of the performances of the models using different error and statistical measures indicates that the SVM-based model performed better than all the other models in reproducing most monthly rainfall statistics at 18 sites. Output from the third-generation CGCM3 GCM for the A1B scenario was used for future projections. For the projection period 2001–10, MLR was used to relate variables at the GCM and NCEP grid scales. Use of MLR in linking the predictor variables at the GCM and NCEP grid scales yielded better reproduction of monthly rainfall statistics at most of the stations (12 out of 18) compared to those by spatial interpolation technique used in earlier studies.

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Wang, Taiping, Zhaoqing Yang, Wei-Cheng Wu, and Molly Grear. "A Sensitivity Analysis of the Wind Forcing Effect on the Accuracy of Large-Wave Hindcasting." Journal of Marine Science and Engineering 6, no. 4 (November 14, 2018): 139. http://dx.doi.org/10.3390/jmse6040139.

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Deployment of wave energy converters (WECs) relies on consistent and accurate wave resource characterization, which is typically achieved through numerical modeling using deterministic wave models. The accurate predictions of large-wave events are critical to the success of wave resource characterization because of the risk on WEC installation, maintenance, and damage caused by extreme sea states. Because wind forcing is the primary driver of wave models, the quality of wind data plays an important role in the accuracy of wave predictions. This study evaluates the sensitivity of large-wave prediction to different wind-forcing products, and identifies a feasible approach to improve wave model results through improved wind forcing. Using a multi-level nested-grid modeling approach, we perform a series of sensitivity tests at four representative National Data Buoy Center buoy locations on the U.S. East and West Coasts. The selected wind-forcing products include the Climate Forecast System Reanalysis global wind product and North American Regional Reanalysis regional wind product as well as the observed wind at the buoys. Sensitivity test results indicate a consistent improvement in model predictions for the large-wave events (e.g., >90th percentile of significant wave height) at all buoys when observed-wind data were used to drive the wave model simulations.

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Jin, Tae-Hwan, Ki-Yeol Shin, Mo Chung, and Geon-Pyo Lim. "Development and Performance Verification of Frequency Control Algorithm and Hardware Controller Using Real-Time Cyber Physical System Simulator." Energies 15, no. 15 (August 6, 2022): 5722. http://dx.doi.org/10.3390/en15155722.

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Frequency stability is a critical factor in maintaining the quality of the power grid system. A battery energy storage system (BESS) with quick response and flexibility has recently been used as a primary frequency control (PFC) resource, and many studies on its control algorithms have been conducted. The cyber physic system (CPS) simulator, which can perform virtual physical modelling and verification of many hardware systems connected to the network, is an optimal solution for the performance verification of control algorithms and hardware systems. This study introduces a large-scale real-time dynamic simulator that includes the national power system. This simulator comprises a power grid model, an energy management system (EMS) model, a BESS system model, and a communication model. It performs the control algorithm performance evaluation and the hardware controller’s response performance evaluation. The performance of the control algorithm was evaluated by tracking the power system’s characteristic trajectory in the transient state based on the physical response delay time between the output instruction of the frequency regulation controller (FRC), a hardware controller, and the output response of the BESS. Based on this, we examined the response performance evaluation results by linking them to the optimally designed actual FRC. As a result, we present an analysis of the BESS’s characteristic trajectories in the transient state, such as frequency, power system inertia, and power grid constant, and provide FRC response performance evaluation results at a level of 163 ms, by connecting the BESS installed at the actual site with the CPS simulator.

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Titko, Anna V. "FEATURES OF SIMBIRSK BOLSHEVIKS’ WORK AMONG THE CHUVASH POPULATION (1918–1920)." Historical Search 1, no. 3 (December 21, 2020): 127–31. http://dx.doi.org/10.47026/2712-9454-2020-1-3-127-131.

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The article deals with the problems of creation and activity of the Chuvash national section in 1918–1920 in Simbirsk. The analysis of document kept at the State Archives of Modern History of Ulyanovsk region is indicative of the national rise of the Chuvash people after the February Revolution of 1917; it shows a high level of education among the Chuvash communists. The work experience of Chuvash Bolsheviks among the population is analyzed. Errors and achievements of propaganda work among the Chuvash population of the province are shown. In Simbirsk province 250 thousand Chuvash lived, and Simbirsk was a recognized Chuvash cultural and educational center. From 1868 the Chuvash Teacher Seminary worked in the town, which launched the beginning of national intelligentsia formation. Graduates and students of the seminary (27 persons) became members of the Chuvash section of the RCP(b), setting the task of conducting propaganda and campaigning among the Chuvash population in their native language. The members of the section were young, energetic and fairly well educated. They were able to deploy the work on the scale of the whole province but they made mistakes: they put emphasis on the printed word. Most of the peasants were illiterate. Neither the calls of the Chuvash communists to create collective farms caused their sympathy. The members of the section found the right path to the masses. They noticed a passionate interest of the Chuvash population in art. Since the autumn 1919 all the public speakings of activists were accompanied by performances and singing of national choirs. Success was not long in coming.

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Nielsen, N. H., M. R. A. Larsen, and S. F. Rasmussen. "Development of a screening method to assess flood risk on Danish national roads and highway systems." Water Science and Technology 63, no. 12 (June 1, 2011): 2957–66. http://dx.doi.org/10.2166/wst.2011.157.

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A method to assess flood risk on Danish national roads in a large area in the middle and southern part of Jutland, Denmark, was developed for the Danish Road Directorate. Flood risk has gained renewed focus due to the climate changes in recent years and extreme rain events are expected to become more frequent in the future. The assessment was primarily based on a digital terrain model (DTM) covering 7,500 km2 in a 1.6 × 1.6 m grid. The high-resolution terrain model was chosen in order to get an accurate estimation of the potential flooding in the road area and in the immediate vicinity, but also put a high requirement on the methods, hardware and software applied. The outcome of the analysis was detailed maps (as GIS layers) illustrating the location of depressions with depths, surface area and volume data for each depression. Furthermore, preferential flow paths, catchment boundaries and ranking of each depression were calculated. The ranking was based on volume of depressions compared with upstream catchment and a sensitivity analysis of the runoff coefficient. Finally, a method for assessing flood risk at a more advanced level (hydrodynamic simulation of surface and drainage) was developed and used on a specific blue spot as an example. The case study shows that upstream catchment, depressions, drainage system, and use of hydrodynamic calculations have a great influence on the result. Upstream catchments can contribute greatly to the flooding.

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Kulakov, G. T., and K. I. Artsiomenka. "SYSTEM ANALYSIS OF SCIENTIFIC-AND-TECHNICAL INFORMATION IN AUTOMATIC CONTROL SYSTEM OF POWER UNITS WATTAGE." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 60, no. 5 (September 28, 2017): 446–58. http://dx.doi.org/10.21122/1029-7448-2017-60-5-446-458.

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The production, transformation, transmission, distribution and consumption of electricity is one continuous process. The change of the load, i.e. the level of energy consumption, should cause a corresponding change in the level of generated energy. It means that the power system should be a balance of produced and consumed energy, taking into account technological cost of conversion, transmission and distribution. Otherwise, electric power quality indicators will be violated. For example, at infringement of balance of active power the frequency in the grid will have a value different from 50 Hz. One of the automatic devices on the lowest rung in the hierarchy of automatic dispatcher control system of frequency and power interchange is the system of automatic control of power units (SACPU). It is a comprehensive and complex device, which consists of several connected together simpler systems, governing all thermal power devices of a power unit. SACPU ought to regulate the active power of the unit and participate in primary frequency regulation in the network with a given accuracy and sensitivity; also, it ought to be adequately fast. At the same time, this device should be simple from the point of view of technical implementation, easy to use, allow one to maintain a high level of efficiency, reliability, durability and environmental performance of the units. To satisfy all these requirements (often conflicting) simultaneously, SACPU should have a certain structure, which depends on the composition and characteristics of heat power equipment of the power unit and on operating modes. The analysis of known SACPU have demonstrated that they are unable to fully provide the requirements of the modern standards for quality control of frequency and power, i.e. the SACPU models are still in need of structural and parametric optimization on the basis of the proximate methods developed at the Belarusian National Technical University.

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Karapidakis, Emmanuel, Antonis Tsikalakis, Alexandros Paspatis, Emmanuel Fotakis, George Stavrakakis, Christina Chatzipoulka, and Panagiotis Zervas. "Grid Operation Assessment under a Specific EV Chargers Deployment Plan in the City of Heraklion." Electronics 10, no. 22 (November 18, 2021): 2831. http://dx.doi.org/10.3390/electronics10222831.

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The development of electric vehicles (EVs) as part of the electrification of the transportation sector plays a significant role in energy transition to a low-carbon and highly renewable society. The use of EVs has been promoted through the development of inclusive strategies for electromobility in the recent years. Apart from actions directed and funded by the European Union, national strategies have also been employed to support electromobility. Such a strategic plan has already been enacted by the Hellenic Ministry of Environment and Energy, funding municipalities to prepare siting and sizing plans for electric vehicle chargers. In this paper, the final study of this strategic plan for the municipality of Heraklion in Crete is used as a case study to investigate the effect of EV chargers on the operation of the Cretan power system. Their selected siting points are evaluated by performing a power flow analysis at the level of 150 kV. Thus, they are aggregated in each 20 kV/150 kV distribution substation of the electrical grid with the aim of investigating their effect on substation loading and transmission line losses. Generally, extensive fast charging should be avoided to minimize the risk of sudden stress of the existing cities’ grids and control strategies should be implemented to mitigate the need for upscale substation equipment or even postpone reinforcements.

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BADEA, Ovidiu, Diana Maria SILAGHI, Stefan NEAGU, Ioan TAUT, and Stefan LECA. "Forest Monitoring - Assessment, Analysis and Warning System for Forest Ecosystem Status." Notulae Botanicae Horti Agrobotanici Cluj-Napoca 41, no. 2 (December 6, 2013): 613. http://dx.doi.org/10.15835/nbha4129304.

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Forests provide essential benefits and services as an important component of terrestrial ecosystems. Their functionality and health result from multiple and cumulative interactions of biotic and abiotic stress factors such as air pollution, climate change, changes in land use, and poor management practices. A forest monitoring system was established to identify, analyse and assess the degradation of European forests. Two levels of forest monitoring were developed: I) large-scale forest condition surveys, based on an European grid system starting in 1986 and II) an intensive non-systematic survey network placed in representative forest ecosystems starting in 1994. Romania implemented both level I (1990-1991) and level II (1991-1992) forest monitoring surveys with the results showing the effects of increased air temperatures and a drastic decrease of precipitation since the decade of 1971-1980. Thus, the highest values of damaged trees (crown defoliation >25%) percent were recorded in 1993, 1994, 2000 and 2003 both in the national and European networks. Also, in southern and South-Eastern Romania the forests are more frequently damaged as a response to worsening of climatic factors in this region in recent decades, with temperatures rising 0.7-0.8Â°C. In general, in Romania, ozone concentrations remained below the critical threshold (40-50 ppb) for affecting growth or health of trees. The levels of S-SO4 and N-NO3 declined in the atmosphere but the accumulation continued to increase in the soil, leading to soil acidification, mainly at depths of 10-40 cm). In general, during the last decade, Romanian forests were affected at low to medium intensities with damage rate up to 11% of the trees and the status of general forest health improved slightly.

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Journal articles on the topic 'Energetic analysis at the national grid level'

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