Once three young men went hunting in the woods and took a-long another to be the cook.They hunted all day long withoutstopping to eat,and when evening came they had caught nothingbut one partridge(鹧鹕).One little bir...Once three young men went hunting in the woods and took a-long another to be the cook.They hunted all day long withoutstopping to eat,and when evening came they had caught nothingbut one partridge(鹧鹕).One little bird was hardly enough for four hungry men,sothey hit upon(突然想起)a plan.They would save the partridgefor breakfast,and whoever dreamed the best dream in the nightshould have it.Then they went to sleep.展开更多
Sister Carrie is called the quintessential modern American novel. By depicting Carrie's legendary experience, the story illustrates how the changing economic structure affects the American's life. This article...Sister Carrie is called the quintessential modern American novel. By depicting Carrie's legendary experience, the story illustrates how the changing economic structure affects the American's life. This article's main objective is to analyze how the main character: carrie achieves her success.展开更多
You may have heard of the"American Dream",an ideal that has powered the hopes of Americans for generations.It began as a belief that the US was a land of"opportunity,and that anyone could achieve succes...You may have heard of the"American Dream",an ideal that has powered the hopes of Americans for generations.It began as a belief that the US was a land of"opportunity,and that anyone could achieve success through hard work.At times,the dream has referred to home ownership,a good job,retirement security or each generation doing better than the last.Yet today,this concept seems to have greatly changed.As Time magazine pointed out,quite展开更多
传统有源电力滤波器(active power filter,APF)基于逆变器拓扑,直流侧采用大容量电解电容器组作为储能元件,容易损坏,且价格昂贵。提出一种基于推挽正激式高频隔离交交变换器(insolated high frequency push-pull forward AC-AC convert...传统有源电力滤波器(active power filter,APF)基于逆变器拓扑,直流侧采用大容量电解电容器组作为储能元件,容易损坏,且价格昂贵。提出一种基于推挽正激式高频隔离交交变换器(insolated high frequency push-pull forward AC-AC converter,IHF-PPFAC)的IL-APF(inverter-less APF)结构,无需储能装置。分析了基于偶次谐波调制技术(even harmonic modulation,EHM)的单相IHF-PPFAC综合补偿原理;对补偿注入电流进行傅里叶级数分解分析其频谱特性,发现EHM耦合问题并提出非相邻调制波的解决方案;提出三相IL-APF结构,并建立了数学模型;同时设计了逐次谐波补偿策略(successive harmonic compensation strategy,SHCS)的闭环控制方案。仿真和实验结果验证了IL-APF的可行性,新装置没有使用直流储能元件,并实现了补偿电容器和电网侧的电气隔离;具有无功和谐波的综合补偿功能,适用于三相三线平衡系统。展开更多
With the rapid development of economy and increase of population in the drainage areas, the nutrient loading has increased dramatically in the Changjiang estuary and adjacent coastal waters. To properly assess the imp...With the rapid development of economy and increase of population in the drainage areas, the nutrient loading has increased dramatically in the Changjiang estuary and adjacent coastal waters. To properly assess the impact of nutrient enrichment on phytoplankton community, seasonal microcosm experiments were conducted during August 2010-July 2011 in the coastal waters of Zhejiang Province. The results of the present study indicated that the chl a concentration, cell abundance, diversity indices, species composition and community succession of the phytoplankton varied significantly with different N/P ratios and seasons. Higher growth was observed in the 64：1 （spring）, 32：1 （summer）, 16：1 （autumn） and 128：1,256：1 （winter） treatments, respectively. The values of Shannon-Wiener index （H） and Pielou evenness index （J） were lower in the 8：1 and 16：1 treatments in autumn test, while H value was higher in the 128：1 and 8：1 treatments in winter test. A definite community succession order from diatoms to dinoflagel lares was observed in the autumn and winter tests, while the diatoms dominated the community throughout the culture in the spring and summer tests.展开更多
文摘Once three young men went hunting in the woods and took a-long another to be the cook.They hunted all day long withoutstopping to eat,and when evening came they had caught nothingbut one partridge(鹧鹕).One little bird was hardly enough for four hungry men,sothey hit upon(突然想起)a plan.They would save the partridgefor breakfast,and whoever dreamed the best dream in the nightshould have it.Then they went to sleep.
文摘Sister Carrie is called the quintessential modern American novel. By depicting Carrie's legendary experience, the story illustrates how the changing economic structure affects the American's life. This article's main objective is to analyze how the main character: carrie achieves her success.
文摘You may have heard of the"American Dream",an ideal that has powered the hopes of Americans for generations.It began as a belief that the US was a land of"opportunity,and that anyone could achieve success through hard work.At times,the dream has referred to home ownership,a good job,retirement security or each generation doing better than the last.Yet today,this concept seems to have greatly changed.As Time magazine pointed out,quite
文摘传统有源电力滤波器(active power filter,APF)基于逆变器拓扑,直流侧采用大容量电解电容器组作为储能元件,容易损坏,且价格昂贵。提出一种基于推挽正激式高频隔离交交变换器(insolated high frequency push-pull forward AC-AC converter,IHF-PPFAC)的IL-APF(inverter-less APF)结构,无需储能装置。分析了基于偶次谐波调制技术(even harmonic modulation,EHM)的单相IHF-PPFAC综合补偿原理;对补偿注入电流进行傅里叶级数分解分析其频谱特性,发现EHM耦合问题并提出非相邻调制波的解决方案;提出三相IL-APF结构,并建立了数学模型;同时设计了逐次谐波补偿策略(successive harmonic compensation strategy,SHCS)的闭环控制方案。仿真和实验结果验证了IL-APF的可行性,新装置没有使用直流储能元件,并实现了补偿电容器和电网侧的电气隔离;具有无功和谐波的综合补偿功能,适用于三相三线平衡系统。
基金supported by the Ministry of Science and Technology of P.R.China under grant contracts (No.2010CB428903)the National Natural Science Foundation of China (No.41306112)+3 种基金the National Marine Public Welfare Research Project of China (Nos.201305043,200805069)the Zhejiang Provincial Natural Science Foundation (Nos.LY13D060004,Y5110131)the Marine Science Foundation of State Oceanic Administration for Youth (Nos.2013140,2013144)the Basic Scientific Research Fund of SIO,China (Nos.JG1311,JG1221)
文摘With the rapid development of economy and increase of population in the drainage areas, the nutrient loading has increased dramatically in the Changjiang estuary and adjacent coastal waters. To properly assess the impact of nutrient enrichment on phytoplankton community, seasonal microcosm experiments were conducted during August 2010-July 2011 in the coastal waters of Zhejiang Province. The results of the present study indicated that the chl a concentration, cell abundance, diversity indices, species composition and community succession of the phytoplankton varied significantly with different N/P ratios and seasons. Higher growth was observed in the 64：1 （spring）, 32：1 （summer）, 16：1 （autumn） and 128：1,256：1 （winter） treatments, respectively. The values of Shannon-Wiener index （H） and Pielou evenness index （J） were lower in the 8：1 and 16：1 treatments in autumn test, while H value was higher in the 128：1 and 8：1 treatments in winter test. A definite community succession order from diatoms to dinoflagel lares was observed in the autumn and winter tests, while the diatoms dominated the community throughout the culture in the spring and summer tests.
