Two new different metal-organic frameworks(MOFs)[Ba(L1)(H_(2)O)_(2)]_(n)·nH_(2)O(MOF 1)and[Ba(L2)(-n2 O)_(2)]_(n)·0.5 nDMF·0.5 nH_(2)O(MOF 2)were yielded by the assembly of oxygen-friendly Ba(Ⅱ)ions an...Two new different metal-organic frameworks(MOFs)[Ba(L1)(H_(2)O)_(2)]_(n)·nH_(2)O(MOF 1)and[Ba(L2)(-n2 O)_(2)]_(n)·0.5 nDMF·0.5 nH_(2)O(MOF 2)were yielded by the assembly of oxygen-friendly Ba(Ⅱ)ions and two similar linkers,namely 2-(imidazol-1-yl)terephthalic acid(H_(2)L1)and 2-(1 H-1,2,4-triazol-1-yl)terephthalic acid(H_(2)L2).Single-crystal X-ray diffractions(XRD)indicate that MOF1 is a new three-dimensional(3 D)stacking dense network formed by the one-dimensional(1 D)rod-shaped chains and L1 linkers,whereas MOF 2 presents a 3 D nanotube porous framework with cylindrical tunnels based on the 1 D loop chains as the secondary building units(SBUs)by replacing the imidazole group in H_(2)L1 with the triazole group in H_(2)L2.As a result,MOF 2 has a higher density of active sites and Lewis acid sites in the porous surface of nanotube than MOF 1.Thereby,the CO_(2)capture and separation capacity of MOF 2 is great higher than that of CH_(4)at298 K.展开更多
As the world’s top two economies,the United States(U.S.)and China face a number of similar water resources problems.Yet,few studies have been done to systematically compare policies and approaches on water resources ...As the world’s top two economies,the United States(U.S.)and China face a number of similar water resources problems.Yet,few studies have been done to systematically compare policies and approaches on water resources management between China and the U.S.This study compares water resources policies of China and the U.S.in the areas of national authority,water supply,water quality,and ecosystem use of the water to draw lessons learned and shed light on water resources management in China,the U.S.,and the rest of the world.The lessons learned from the comparison include six aspects.1)New paradigms of people-water harmony and a water-saving society are urgently needed to address the pressing water crisis and achieve the United Nations Sustainable Development Goals(UN SDGs).2)A comprehensive,consistent,forward-looking national policy is necessary to achieve sustainable use of water resources.3)Empowerment of river basin commissions with comprehensive authority over the integrative management of air,land,water,and biological resources in the river basin could significantly enhance the benefits and effectiveness of economic development and environmental protection.4)Expansion of water exchange through market mechanisms among water users promotes efficient and beneficial water uses.5)Use of water for ecosystem services should be an integral part of water resources management.China has set up a national blueprint for achieving ecological civilization;maintaining appropriate amounts of flow in rivers and lakes for maintenance of wildlife and fisheries and ecosystems should be institutionalized as part of this national strategy as well.6)By sharing their rich experiences and lessons in water resources management,economic development,and ecological protection with other countries,China and the U.S.can help the world to achieve global human-water harmony and the UN SDGs.展开更多
Many energy consuming countries have carried out research, development, demonstration, planning and deployment of coal-to-liquids (CTL) because of its ability to replace oil imports by converting coal resources into f...Many energy consuming countries have carried out research, development, demonstration, planning and deployment of coal-to-liquids (CTL) because of its ability to replace oil imports by converting coal resources into fuel. Among them, China and South Africa successfully had their CTL technology industrialized, while the United States did not. To understand the differences in the industrial development level, a comparative study is necessary. This paper compares the history, driver and policy of CTL industry in China, South Africa and United States, collates and discloses numbers of industry details for the first time. We figure out that the motivation, top level planning and policy consistency are the key indicators of the difference on the industrial development level. Among them, the key to the success of CTL industrialization in China and South Africa is the government’s strong and stable determination to improve energy security, which provides a stable top-level planning and robust policy support. The failure of CTL in United States is caused by the shift of policy attention after its energy security situation improved.展开更多
It is well-known that the United States,a highly developed country whether in high-tech.or higher education,is in a leading position in the world.Based on the comparison and analysis of higher education between China ...It is well-known that the United States,a highly developed country whether in high-tech.or higher education,is in a leading position in the world.Based on the comparison and analysis of higher education between China and the U.S.,this article highly affirms the advantages of American higher education,offers an objective comment on China's higher education reform in recent years,and earnestly indicates that China's higher education needs to be improved in order to facilitate greater development.展开更多
This article introduces a novel 20 V radiation-hardened high-voltage metal-oxide-semiconductor field-effect transistor(MOSFET)driver with an optimized input circuit and a drain-surrounding-source(DSS)structure.The inp...This article introduces a novel 20 V radiation-hardened high-voltage metal-oxide-semiconductor field-effect transistor(MOSFET)driver with an optimized input circuit and a drain-surrounding-source(DSS)structure.The input circuit of a conventional inverter consists of a thick-gate-oxide n-type MOSFET(NMOS).These conventional drivers can tolerate a total ionizing dose(TID)of up to 100 krad(Si).In contrast,the proposed comparator input circuit uses both a thick-gate-oxide p-type MOSFET(PMOS)and thin-gate-oxide NMOS to offer a high input voltage and higher TID tolerance.Because the thick-gate-oxide PMOS and thin-gate-oxide NMOS collectively provide better TID tolerance than the thick-gate-oxide NMOS,the circuit exhibits enhanced TID tolerance of>300 krad(Si).Simulations and experimental date indicate that the DSS structure reduces the probability of unwanted parasitic bipolar junction transistor activation,yielding a better single-event effect tolerance of over 81.8 MeVcm^(2)mg^(-1).The innovative strategy proposed in this study involves circuit and layout design optimization,and does not require any specialized process flow.Hence,the proposed circuit can be manufactured using common commercial 0.35μm BCD processes.展开更多
The comparative advantage of maize production in Jilin Province was analyzed based on the sow area index,unit yield index,benefit index and comprehensive comparative advantage index in this study.The results showed th...The comparative advantage of maize production in Jilin Province was analyzed based on the sow area index,unit yield index,benefit index and comprehensive comparative advantage index in this study.The results showed that compared with other provinces in China,there was obvious comparative advantage in sow area index and unit yield index of maize in Jilin,the average of which stood for the first and the fourth in China from 2002 to 2006;there was no comparative advantage of benefit index compared with the average value of the whole countries,the average of which stood for the 14th in China from 2002 to 2006;the comprehensive comparative advantage in Jilin provincial maize production showed significant comparative advantage,the average of which stood for the fourth in China from 2002 to 2006.On the basis of the above,the suggestions to develop maize production in Jilin province had been put forward.展开更多
China and the United States are the two most significant nations in the contemporary global food and agricultural network.In addition,they are two of the most important innovators with respect to the development of ne...China and the United States are the two most significant nations in the contemporary global food and agricultural network.In addition,they are two of the most important innovators with respect to the development of new crop varieties,agro-technologies,farm products,markets and consumer issues,such as consumer resistance to genetically modified foods,among others.In the face of an ever-complex web of interactions,technologies and products among producers and consumers in both nations,there are far more structural similarities than differences in the food and agriculture sectors of these two nations.This essay,adopting some of the themes of the Sino-American Symposium on Future Issues Affecting Quality of Life,presents a limited but representative comparative assessment of three of the most important shared challenges impacting the agricultural sectors of China and the United States for the period from 2000 to the present including 1)environmental challenges related to agricultural water supply,2)declines in farm labor and rural population,and 3)growing food-related concerns and challenges.For both nations,excessive and unsustainable groundwater consumption has lowered water tables and limited crop production.Rural populations and farm workforces in both nations are also declining,leading to labor challenges in both nations.Finally,concerns regarding food safety are also very similar with major challenges to the farm sector associated with consumer resistance to genetically modified food crops and sanitation issues linked to lengthening supply chains.All of these issues threaten the development of sustainable agricultural production systems.展开更多
The coal-fired power unit integration with a CO2 capture and compression installation involves a considerable rise in the costs of electricity generation. Therefore, there is a need for a continuous search for methods...The coal-fired power unit integration with a CO2 capture and compression installation involves a considerable rise in the costs of electricity generation. Therefore, there is a need for a continuous search for methods of improving the electricity generation efficiency in steam power plants. One technology which is especially promising is the advanced ultra-supercritical (A-USC) power unit. Apart from steam parameters upstream the turbine, the overall efficiency also depends on the efficiency values of individual elements of the plant and the size of energy consumption of the process of CO2 sequestration from the boiler flue gases. These problems are considered herein to emphasize that without specifying the efficiency values of the power plant main elements the information concerning its electricity generation efficiency is incomplete. This paper presents the influence of the efficiency of individual elements of the power plant on its electricity generation efficiency. The lack of information of the efficiencies of the power plant individual elements, by presenting its overall efficiency, may lead to the false conclusions.展开更多
The paper proposes a stochastic unit commitment(UC)model to realize the low-carbon operation requirement and cope with wind power prediction errors for power systems with intensive wind power and carbon capture power ...The paper proposes a stochastic unit commitment(UC)model to realize the low-carbon operation requirement and cope with wind power prediction errors for power systems with intensive wind power and carbon capture power plant(CCPP).A linear re-dispatch strategy is introduced to compensate the wind power deviation from the spot forecast.The robust optimization technique is employed to obtain a reliable commitment plan against all realizations of wind power within the uncertainty set given by probabilistic forecast.The proposed model is validated with IEEE 39-bus system.The advantages of flexible CCPPs are compared to the normal coal-fueled plants and the impacts of robustness controlling are discussed.展开更多
基金the National Natural Science Foundation of China(Nos.21971207 and21801111)the Project of Central Plains Science and Technology Innovation Leading Talents of Henan Province(No.204200510001)the Natural Science Foundation of Shaanxi Province(No.2019JM-013)。
文摘Two new different metal-organic frameworks(MOFs)[Ba(L1)(H_(2)O)_(2)]_(n)·nH_(2)O(MOF 1)and[Ba(L2)(-n2 O)_(2)]_(n)·0.5 nDMF·0.5 nH_(2)O(MOF 2)were yielded by the assembly of oxygen-friendly Ba(Ⅱ)ions and two similar linkers,namely 2-(imidazol-1-yl)terephthalic acid(H_(2)L1)and 2-(1 H-1,2,4-triazol-1-yl)terephthalic acid(H_(2)L2).Single-crystal X-ray diffractions(XRD)indicate that MOF1 is a new three-dimensional(3 D)stacking dense network formed by the one-dimensional(1 D)rod-shaped chains and L1 linkers,whereas MOF 2 presents a 3 D nanotube porous framework with cylindrical tunnels based on the 1 D loop chains as the secondary building units(SBUs)by replacing the imidazole group in H_(2)L1 with the triazole group in H_(2)L2.As a result,MOF 2 has a higher density of active sites and Lewis acid sites in the porous surface of nanotube than MOF 1.Thereby,the CO_(2)capture and separation capacity of MOF 2 is great higher than that of CH_(4)at298 K.
文摘As the world’s top two economies,the United States(U.S.)and China face a number of similar water resources problems.Yet,few studies have been done to systematically compare policies and approaches on water resources management between China and the U.S.This study compares water resources policies of China and the U.S.in the areas of national authority,water supply,water quality,and ecosystem use of the water to draw lessons learned and shed light on water resources management in China,the U.S.,and the rest of the world.The lessons learned from the comparison include six aspects.1)New paradigms of people-water harmony and a water-saving society are urgently needed to address the pressing water crisis and achieve the United Nations Sustainable Development Goals(UN SDGs).2)A comprehensive,consistent,forward-looking national policy is necessary to achieve sustainable use of water resources.3)Empowerment of river basin commissions with comprehensive authority over the integrative management of air,land,water,and biological resources in the river basin could significantly enhance the benefits and effectiveness of economic development and environmental protection.4)Expansion of water exchange through market mechanisms among water users promotes efficient and beneficial water uses.5)Use of water for ecosystem services should be an integral part of water resources management.China has set up a national blueprint for achieving ecological civilization;maintaining appropriate amounts of flow in rivers and lakes for maintenance of wildlife and fisheries and ecosystems should be institutionalized as part of this national strategy as well.6)By sharing their rich experiences and lessons in water resources management,economic development,and ecological protection with other countries,China and the U.S.can help the world to achieve global human-water harmony and the UN SDGs.
文摘Many energy consuming countries have carried out research, development, demonstration, planning and deployment of coal-to-liquids (CTL) because of its ability to replace oil imports by converting coal resources into fuel. Among them, China and South Africa successfully had their CTL technology industrialized, while the United States did not. To understand the differences in the industrial development level, a comparative study is necessary. This paper compares the history, driver and policy of CTL industry in China, South Africa and United States, collates and discloses numbers of industry details for the first time. We figure out that the motivation, top level planning and policy consistency are the key indicators of the difference on the industrial development level. Among them, the key to the success of CTL industrialization in China and South Africa is the government’s strong and stable determination to improve energy security, which provides a stable top-level planning and robust policy support. The failure of CTL in United States is caused by the shift of policy attention after its energy security situation improved.
文摘It is well-known that the United States,a highly developed country whether in high-tech.or higher education,is in a leading position in the world.Based on the comparison and analysis of higher education between China and the U.S.,this article highly affirms the advantages of American higher education,offers an objective comment on China's higher education reform in recent years,and earnestly indicates that China's higher education needs to be improved in order to facilitate greater development.
基金supported by the National Natural Science Foundation of China(U2241221).
文摘This article introduces a novel 20 V radiation-hardened high-voltage metal-oxide-semiconductor field-effect transistor(MOSFET)driver with an optimized input circuit and a drain-surrounding-source(DSS)structure.The input circuit of a conventional inverter consists of a thick-gate-oxide n-type MOSFET(NMOS).These conventional drivers can tolerate a total ionizing dose(TID)of up to 100 krad(Si).In contrast,the proposed comparator input circuit uses both a thick-gate-oxide p-type MOSFET(PMOS)and thin-gate-oxide NMOS to offer a high input voltage and higher TID tolerance.Because the thick-gate-oxide PMOS and thin-gate-oxide NMOS collectively provide better TID tolerance than the thick-gate-oxide NMOS,the circuit exhibits enhanced TID tolerance of>300 krad(Si).Simulations and experimental date indicate that the DSS structure reduces the probability of unwanted parasitic bipolar junction transistor activation,yielding a better single-event effect tolerance of over 81.8 MeVcm^(2)mg^(-1).The innovative strategy proposed in this study involves circuit and layout design optimization,and does not require any specialized process flow.Hence,the proposed circuit can be manufactured using common commercial 0.35μm BCD processes.
基金Supported by Key Projects in the National Science & Technology Pillar Program in the Eleventh Five-year Plan Period(2007BAD98B06)Scientific Research Foundation of Jilin Agricultural University~~
文摘The comparative advantage of maize production in Jilin Province was analyzed based on the sow area index,unit yield index,benefit index and comprehensive comparative advantage index in this study.The results showed that compared with other provinces in China,there was obvious comparative advantage in sow area index and unit yield index of maize in Jilin,the average of which stood for the first and the fourth in China from 2002 to 2006;there was no comparative advantage of benefit index compared with the average value of the whole countries,the average of which stood for the 14th in China from 2002 to 2006;the comprehensive comparative advantage in Jilin provincial maize production showed significant comparative advantage,the average of which stood for the fourth in China from 2002 to 2006.On the basis of the above,the suggestions to develop maize production in Jilin province had been put forward.
文摘China and the United States are the two most significant nations in the contemporary global food and agricultural network.In addition,they are two of the most important innovators with respect to the development of new crop varieties,agro-technologies,farm products,markets and consumer issues,such as consumer resistance to genetically modified foods,among others.In the face of an ever-complex web of interactions,technologies and products among producers and consumers in both nations,there are far more structural similarities than differences in the food and agriculture sectors of these two nations.This essay,adopting some of the themes of the Sino-American Symposium on Future Issues Affecting Quality of Life,presents a limited but representative comparative assessment of three of the most important shared challenges impacting the agricultural sectors of China and the United States for the period from 2000 to the present including 1)environmental challenges related to agricultural water supply,2)declines in farm labor and rural population,and 3)growing food-related concerns and challenges.For both nations,excessive and unsustainable groundwater consumption has lowered water tables and limited crop production.Rural populations and farm workforces in both nations are also declining,leading to labor challenges in both nations.Finally,concerns regarding food safety are also very similar with major challenges to the farm sector associated with consumer resistance to genetically modified food crops and sanitation issues linked to lengthening supply chains.All of these issues threaten the development of sustainable agricultural production systems.
基金The results presented in this paper were obtained from research work co-financed by the Polish National Centre of Research and Development in the framework of Contract SP/E/1/67484/10—Strategic Research Programme—Advanced technologies for energy generation:Development of a technology for highly efficient zero-emission coal-fired power units integrated with CO2 capture.
文摘The coal-fired power unit integration with a CO2 capture and compression installation involves a considerable rise in the costs of electricity generation. Therefore, there is a need for a continuous search for methods of improving the electricity generation efficiency in steam power plants. One technology which is especially promising is the advanced ultra-supercritical (A-USC) power unit. Apart from steam parameters upstream the turbine, the overall efficiency also depends on the efficiency values of individual elements of the plant and the size of energy consumption of the process of CO2 sequestration from the boiler flue gases. These problems are considered herein to emphasize that without specifying the efficiency values of the power plant main elements the information concerning its electricity generation efficiency is incomplete. This paper presents the influence of the efficiency of individual elements of the power plant on its electricity generation efficiency. The lack of information of the efficiencies of the power plant individual elements, by presenting its overall efficiency, may lead to the false conclusions.
基金This work was supported by the National Basic Research Program of China(No.2012CB215106)State Grid Corporation of China(No.52150014006W).
文摘The paper proposes a stochastic unit commitment(UC)model to realize the low-carbon operation requirement and cope with wind power prediction errors for power systems with intensive wind power and carbon capture power plant(CCPP).A linear re-dispatch strategy is introduced to compensate the wind power deviation from the spot forecast.The robust optimization technique is employed to obtain a reliable commitment plan against all realizations of wind power within the uncertainty set given by probabilistic forecast.The proposed model is validated with IEEE 39-bus system.The advantages of flexible CCPPs are compared to the normal coal-fueled plants and the impacts of robustness controlling are discussed.
