Distributed generators now is widely used in electrical power networks, in some cases it works seasonally, and some types works at special weather conditions like photo voltaic systems and wind energy, and due to this...Distributed generators now is widely used in electrical power networks, in some cases it works seasonally, and some types works at special weather conditions like photo voltaic systems and wind energy, and due to this continuous changes in generation condition, the fault current level in network will be affected, this changes in fault current level will affect in the coordination between protection relays and to keep the coordination at right way, an adaptive protection system is required that can adaptive its setting according to generation changes, the fault current level in each case is evaluated using ETAP software, and the required relay setting in each case is also evaluated using Grey Wolf Optimizer (GWO) algorithm, and to select suitable setting which required in each condition, to select the active setting group of protection relay according to generation capacity, central protection unite can be used, and to improve protection stability and minimizing relays tripping time, a proposed method for selecting suitable backup relay is used, which leads to decrease relays tripping time and increase system stability, output settings for relays in all cases achieved our constrains.展开更多
For a square-free integer d other than 0 and 1, let K = Q（√d）, where Q is the set of rational numbers. Then K is called a quadratic field and it has degree 2 over Q. For several quadratic fields K = Q（√d）, the r...For a square-free integer d other than 0 and 1, let K = Q（√d）, where Q is the set of rational numbers. Then K is called a quadratic field and it has degree 2 over Q. For several quadratic fields K = Q（√d）, the ring Rd of integers of K is not a unique-factorization domain. For d 〈 0, there exist only a finite number of complex quadratic fields, whose ring Rd of integers, called complex quadratic ring, is a unique-factorization domain, i.e., d = -1,-2,-3,-7,-11,-19,-43,-67,-163. Let Q denote a prime element of Rd, and let n be an arbitrary positive integer. The unit groups of Rd/（Q^n） was determined by Cross in 1983 for the case d = -1. This paper completely determined the unit groups of Rd/（Q^n） for the cases d = -2, -3.展开更多
In this paper, we completely determine the structure of the unit group of the group algebra of some dihedral groups D2 n over the finite field Fpk, where p is a prime.
Representing the appeals of its industry,the high-tech interest group has recently become an emerging political force in the United States.With abundant financial resources and proficiency in political communication,t...Representing the appeals of its industry,the high-tech interest group has recently become an emerging political force in the United States.With abundant financial resources and proficiency in political communication,the group rapidly grows to be a significant force in the American political sphere.It has started to affect the internal and foreign affairs of the U.S.and played a proactive role in the latest presidential election.Since the high-tech interest group has already become and will continue to be a big player in Sino-U.S.relations,China should carefully deal with its appeals and conflict of interests,and try to develop this group into a stabilizer between the two countries.展开更多
OUR"COVER GIRL"for this issue is a young woman of the Lisu minority who lives in the Nu River valley of China's southwestern Yunnan Province.A number of color pictures,together with two articles in the i...OUR"COVER GIRL"for this issue is a young woman of the Lisu minority who lives in the Nu River valley of China's southwestern Yunnan Province.A number of color pictures,together with two articles in the issue,outline changes that have taken place in Yunnan,the province with the largest diversity of China's ethnic minorities.展开更多
Efficient storage and handling facilities play a pivotal role in ensuring the quality and longevity of date palm produce. This study aims to contribute to the assessment of the operation of refrigeration units in the ...Efficient storage and handling facilities play a pivotal role in ensuring the quality and longevity of date palm produce. This study aims to contribute to the assessment of the operation of refrigeration units in the Drâa Tafilalet region through a diagnostic study conducted by surveying 12 date-packing units. Interviews and surveys were conducted among 12 date packaging units provided by the State to Economic Interest Groups (EIG) in the Drâa-Tafilalet region. Data focused on general EIG information, unit identification, a four-year operational overview, and 2021 palm date processing activities. To streamline analysis, units were categorized into two groups based on packaging capacity: Group 1 (≥400 tons) and Group 2 (<400 tons). The assessment revealed that the packaging units had enhanced this crucial link in the dating industry and introduced a new dynamic in the date marketing chain. However, operational expertise and optimal equipment utilization often fall short, with over 50% of the EIG failing to use provided equipment, except for cold storage rooms. The chain involves a series of operations to preserve the stored product’s intrinsic and extrinsic quality. Evaluated practices include fumigation, meticulous sorting to eliminate visually anomalous dates, calibration during packaging, and storage at temperatures ranging from 0 to 4˚C with humidity levels between 50 and 80%, varying based on the date’s nature (soft, dry, or semi-dry). Expertise in this process mitigates the risk of desiccation or excessive rehydration, preventing date fermentation. Finally, to reduce their energy consumption and solve the balance sheet deficit issue, the government has equipped all the date packaging units from Group 1 and one from Group 2 in the Daraa Tafilalet region with photovoltaic energy. The date packaging infrastructure has boosted the value of Moroccan dates, benefiting small-scale agriculture. Despite improved packaging quality and job creation, suboptimal equipment usage by over 50% of EIGs emphasizes the need for enhanced operational efficiency.展开更多
文摘Distributed generators now is widely used in electrical power networks, in some cases it works seasonally, and some types works at special weather conditions like photo voltaic systems and wind energy, and due to this continuous changes in generation condition, the fault current level in network will be affected, this changes in fault current level will affect in the coordination between protection relays and to keep the coordination at right way, an adaptive protection system is required that can adaptive its setting according to generation changes, the fault current level in each case is evaluated using ETAP software, and the required relay setting in each case is also evaluated using Grey Wolf Optimizer (GWO) algorithm, and to select suitable setting which required in each condition, to select the active setting group of protection relay according to generation capacity, central protection unite can be used, and to improve protection stability and minimizing relays tripping time, a proposed method for selecting suitable backup relay is used, which leads to decrease relays tripping time and increase system stability, output settings for relays in all cases achieved our constrains.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 11461010, 11161006）, the Guangxi Natural Science Foundation （2014GXNSFAAll8005, 2015GXNSFAA139009）, the Guangxi Science Research and Technology Development Project （1599005-2-13）, and the Science Research Fund of Guangxi Education Department （KY2015ZD075）.
文摘For a square-free integer d other than 0 and 1, let K = Q（√d）, where Q is the set of rational numbers. Then K is called a quadratic field and it has degree 2 over Q. For several quadratic fields K = Q（√d）, the ring Rd of integers of K is not a unique-factorization domain. For d 〈 0, there exist only a finite number of complex quadratic fields, whose ring Rd of integers, called complex quadratic ring, is a unique-factorization domain, i.e., d = -1,-2,-3,-7,-11,-19,-43,-67,-163. Let Q denote a prime element of Rd, and let n be an arbitrary positive integer. The unit groups of Rd/（Q^n） was determined by Cross in 1983 for the case d = -1. This paper completely determined the unit groups of Rd/（Q^n） for the cases d = -2, -3.
文摘In this paper, we completely determine the structure of the unit group of the group algebra of some dihedral groups D2 n over the finite field Fpk, where p is a prime.
文摘Representing the appeals of its industry,the high-tech interest group has recently become an emerging political force in the United States.With abundant financial resources and proficiency in political communication,the group rapidly grows to be a significant force in the American political sphere.It has started to affect the internal and foreign affairs of the U.S.and played a proactive role in the latest presidential election.Since the high-tech interest group has already become and will continue to be a big player in Sino-U.S.relations,China should carefully deal with its appeals and conflict of interests,and try to develop this group into a stabilizer between the two countries.
文摘OUR"COVER GIRL"for this issue is a young woman of the Lisu minority who lives in the Nu River valley of China's southwestern Yunnan Province.A number of color pictures,together with two articles in the issue,outline changes that have taken place in Yunnan,the province with the largest diversity of China's ethnic minorities.
文摘Efficient storage and handling facilities play a pivotal role in ensuring the quality and longevity of date palm produce. This study aims to contribute to the assessment of the operation of refrigeration units in the Drâa Tafilalet region through a diagnostic study conducted by surveying 12 date-packing units. Interviews and surveys were conducted among 12 date packaging units provided by the State to Economic Interest Groups (EIG) in the Drâa-Tafilalet region. Data focused on general EIG information, unit identification, a four-year operational overview, and 2021 palm date processing activities. To streamline analysis, units were categorized into two groups based on packaging capacity: Group 1 (≥400 tons) and Group 2 (<400 tons). The assessment revealed that the packaging units had enhanced this crucial link in the dating industry and introduced a new dynamic in the date marketing chain. However, operational expertise and optimal equipment utilization often fall short, with over 50% of the EIG failing to use provided equipment, except for cold storage rooms. The chain involves a series of operations to preserve the stored product’s intrinsic and extrinsic quality. Evaluated practices include fumigation, meticulous sorting to eliminate visually anomalous dates, calibration during packaging, and storage at temperatures ranging from 0 to 4˚C with humidity levels between 50 and 80%, varying based on the date’s nature (soft, dry, or semi-dry). Expertise in this process mitigates the risk of desiccation or excessive rehydration, preventing date fermentation. Finally, to reduce their energy consumption and solve the balance sheet deficit issue, the government has equipped all the date packaging units from Group 1 and one from Group 2 in the Daraa Tafilalet region with photovoltaic energy. The date packaging infrastructure has boosted the value of Moroccan dates, benefiting small-scale agriculture. Despite improved packaging quality and job creation, suboptimal equipment usage by over 50% of EIGs emphasizes the need for enhanced operational efficiency.
