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[en] This work demonstrates and discusses the fabrication of cross-plane configured micro thermoelectric devices for the power generation and thermal management of the photonic devices. The device is fabricated using a cost-effective electrodeposition technique on the silicon wafer with 210 pairs of the electrodeposited p-type BiTe and n-type CuTe pillars. The complete device is fabricated using the flip-chip bonding technique. Our focus in this work is on the challenges in the device fabrication and the solutions employed to overcome the obstacles thereby successfully fabricating the micro thermoelectric device. (paper)
[en] Hydropower is the world's leading renewable energy resources in electricity generation that produces 71% of electricity more than other forms of energy sources such as coal, gas, and oil which are not reliable and gradually diminish day by day. Therefore, hydropower is essential and considered as an economical factor for producing electricity. There are many untapped hydropower resources in the world. The developing country, Myanmar, is also have about 100 GW unexploited energy potential from the rivers for hydropower electrification. This paper is the review paper which presents about the condition of the hydroelectricity in Myanmar in detail.
[en] Overlay welding is commonly applied in numerous industrial fields, such as off-shore plants, nuclear power plants, various power generation facilities, heavy machinery, and large diesel engines. Overlay welding technology is constantly being developed with increasing demand. Therefore, high-productivity and high-quality welds must be obtained. LF occurs frequently in the vicinity of an overlapped part of the bead, and one cause of this is the bead's low spreadability. If the bead spreadability is poor, a problem occurs in which the deviation between the top and the valley of beads increases. In this study, characteristics of both the base material temperature and oscillation were studied for TIG welding using a C-type filler. Results showed that as the temperature of the base material and oscillation width increase, the bead width increases proportionally. The shape of the penetration changes according to the characteristics of the oscillation, and the bead spread ratio converges to 1 as the oscillation width increases.
[en] The state of Rio Grande do Norte is a leader in wind power generation in the country with more than 150 wind farms in operation and 4 GW of installed capacity. Although the wind energy industry continues to grow, there are still very few papers that analyze wind behavior at heights above 80 m, which is typically the height of a wind turbine rotor. In this paper, a 95 m wind behavior analysis was carried out in two wind farms in the city of Parazinho-RN on monthly, seasonal and hourly scale, with the goal of identifying which periods of 2017 were more favorable for wind power production in the region. The wind speed and direction data used in this study were collected by a Thies First Class high precision cup anemometer and a Thies Compact wind direction indicator, corresponding to the hourly average of the measurements performed every second and integrated in intervals of 10 minutes in the period from January 1 to December 31, 2017. According with the results presented in this paper, it was verified that spring is the season of 2017 that presents the highest average monthly wind speeds, with maximum peak in the month of September, while lower speeds vary during the March-April-May quarter. The diurnal period between 10:00 am and 5:00 pm local time is the one with the most frequently wind speed ≥ 10 m.s-1. Wind direction varies from east to south, with predominance of east and southeast directions, in about 80% of the time. During the quarters that correspond to summer and fall, Weibull distributions are more concentrated around 6.5 and 7 m.s-1, indicating that in this period of the year there is a greater probability of occurrence of lower average speeds, implying in lower productivity for wind energy. The opposite is observed in winter and spring, with the exception of June, where the distributions are more concentrated around speeds ≥ 8 m.s-1 and there is a higher probability of higher average speeds to occur, showing that this was the best period of the year 2017 for wind power generation. (author)
[en] 6 points to know about nuclear power in the European Union. Point 1: The European nuclear industry employs 1.1 million people and generates a GDP of 500 billions euros. Point 2: a better coordination between countries is required to face the shutdown of electricity production units in some countries, mainly coal power plants and nuclear power plants. Point 3: the European Union acknowledges that nuclear power combined with renewable energies could be the backbone of a European energy strategy to reach the goal of a climate-neutral economy by 2050. Point 4: there is in Europe a strong divide among countries, only 14 countries use nuclear energy totalling 126 reactors and more than 50% of the installed power is localized in one country. The countries that reject nuclear power must be aware that they will have to operate gas-power plants instead, which would jeopardize their mid- and long- term climate objectives. Point 5: in term of financing, a large priority is given to the fusion research program. Point 6: in the European Union, the energy mix for electricity production is 30% for renewable energies, 26% for nuclear energy, 20% for gas-power plants, and 20% for coal- or oil-power plants. (A.C.)
[en] This study focuses on investigating possible changes in hydrometeorological behavior on important Brazilian river basins for power generation purposes. Thereby, this research analyzes the historical averages and observed trends regarding rainfall and streamflow and their impact on the hydrological regime. Ten river basins were selected for the assessment of alterations in the precipitation and streamflow series throughout descriptive measures and statistical significance tests (Mann-Kendall and Sen’s slope). These data are available over different time spans, but most of the records include information from 1961 to 2006. As long as these river basins are subjected to different climate types, their corresponding rainfall and streamflow patterns vary accordingly the basin location in the country, in addition to the season. Most of the country has a predominantly tropical climate, with a wet period concentrated between October and March and a dry period between April and September. Some exceptions are the Northeastern region, where the climate is semi-arid, besides the Southern region, where there is abundant precipitation throughout the year. According to the obtained results, it could be noted that the streamflow response to precipitation is faster in the smaller river basins, what can be due especially to the water travel time. It was found that Belo Monte basin, in Northern Brazil, presents a statistically significant reduction in the annual rainfall. Furthermore, a significant decrease in the annual streamflow was also identified in Xingó and Sobradinho basins, in the Northeastern region. In contrast, Itaipu basin, located in Southern Brazil, showed increasing statistically significant trends in annual rainfall and streamflow during the second half of the twentieth century. Relevant decreasing trends were also identified in the minimum streamflows of the Brazilian Northern and Northeastern basins and increasing ones in the maximum streamflows in the Southern region basins. The results obtained in this work will support the assessment of the impact of rainfall and streamflow future scenarios in regulating capacity of the hydroelectric power plant reservoirs.
[en] As much wind power is connected to the power system, the accommodation of the wind power in the power grids becomes a huge challenge to the operation model of China’s power system. Releasing and improving the flexibility of the power system will be necessary and important to enable the accommodation of power generated with renewable energy sources, which is connected to the power grids on a large scale and accounts for a high proportion. The paper, with North Hebei as an example, discusses the relationship between the demand for the flexibility of thermal power units and the accommodation of wind power. This paper further analyzes the demand for peak load regulation in North Hebei at both the present and the future as well as the characteristics of power sources in the power grids of North Hebei and the technical potential of power generation. It also compares the quantity of curtailed power before and after the flexibility-oriented transformation of thermal power units in North Hebei and calculates the minimum technical output of thermal power under different levels of accommodation of wind power. The research shows that the peak load regulating resources in the power grids of North Hebei boast huge potential, but in the long term, to achieve the objective of a 10% curtailment rate of power generated with renewable energy sources, the minimum technical output of condensing units must be lower than the internationally advanced level of 25%. So, it is difficult to fulfill the said objective solely relying on the strengthened transformation of generating units. To reach the level of 5% curtailment rate of power generated with renewable energy sources, the minimum technical output must achieve breakthrough improvement, which requires continuous technological innovation and power flexibility in close coordination.
[en] In a few years the fight against climate change has become one of European Union's priorities. The European Commissioner for energy and climate change has recently recalled that electricity will be produced from renewable energies and nuclear energy by 2050. Concerning the fight against climate warming, EU's commitments by 2030 are: -) increasing the production of renewable energies by 32%, -) improving energy efficiency by 32.5% and -) reducing CO2 emissions by 40%. A chart gives the number of operating nuclear reactors in each EU member and also the share of nuclear power in the energy mix. It also appears that a large part of the EU members support nuclear power. Only 6 countries are opposed to nuclear energy: Austria, Denmark, Germany, Italy, Lithuania and Portugal. (A.C.)
[en] This study aims to find in the literature the main works published on innovation and R&D in the Brazilian electric sector and to verify the contribution of the nuclear sector in this group. The technique chosen was the bibliometric analysis with five databases: Emerald, SciELO, Spell, IEEE and the CNEN virtual library. The main results show that the subject is relevant, recent, consistent, but that it is concentrated by some groups of specialists. The results provided an overview of the field of research studied, a comparison of the nuclear sector with the rest of the electricity sector concern innovation projects, a comparison with a previous bibliometric study, but using a different combination of bases and the opportunities for new studies to foster the innovative policy of the Brazilian electricity sector. (author)