The world is facing the third important global power shift.The United States,EU, Japan,Russia,China,and the newly emerging power group are becoming the six big forces in the international center stage,while the former...The world is facing the third important global power shift.The United States,EU, Japan,Russia,China,and the newly emerging power group are becoming the six big forces in the international center stage,while the former three forces and the latter three belong to two groups,waning and waxing respectively.The major shift in the global balance of power is bound to give rise to the transitional multi-polar configuration,which implies a shifting of leadership over the configuration,China and U.S.outweighing other forces,global issues looming large,homogeneity blending with heterogeneity,and a shifting center of world powers.The transitional multi-polar configuration is all about change,upon which China is one of the decisive forces.展开更多
The use of an electrical network as close as possible to its limits can lead to its instability in the event of a high amplitude disturbance. The damping of system oscillations can be achieved by conventional means of...The use of an electrical network as close as possible to its limits can lead to its instability in the event of a high amplitude disturbance. The damping of system oscillations can be achieved by conventional means of voltage and speed regulation but also by FACTS (Flexible AC Transmission Systems) devices, which are increasingly used in power networks. In this work, optimal control coordination between a hybrid power flow controller and a three-level inverter was used to improve the transient stability of a transmission line. The UPFC is a combination of a serial compensator (SSSC) and a parallel compensator (STATCOM) both connected to a DC-LINK DC bus. The SSSC acts as a voltage source for the network and injects a voltage that can be adjusted in phase and amplitude in addition to the network voltage;the STATCOM acts as a current source. The approach used is tested in the Matlab Simulink environment on a single machine network. Optimal controller tuning gives a better transient stability improvement by reducing the transport angle oscillations from 248.17% to 9.85%.展开更多
The effect of transition metal ions(M^(2+)=Mn^(2+),Ni^(2+),Co^(2+),Cu^(2+)) on the chemical synthesis of polyaniline(PANI) used as a platinum-free counter electrode(CE) in dye-sensitized solar cells(DSSCs) was investi...The effect of transition metal ions(M^(2+)=Mn^(2+),Ni^(2+),Co^(2+),Cu^(2+)) on the chemical synthesis of polyaniline(PANI) used as a platinum-free counter electrode(CE) in dye-sensitized solar cells(DSSCs) was investigated.PANI was synthesized by co-polymerization of aniline in the presence of different transition metal ions by using potassium dichromate in acidic medium. It was found that the ion doping of PANI showed a certain catalytic activity for the regeneration of traditional iodide/triiodide(I^-/I_3^-) redox couples. The power conversion efficiency(η) of PANI CEs doped with Mn^(2+),Ni^(2+),Co^(2+) (4.41%, 2.36% and 2.10%, respectively) were higher than 1.94%, the value measured for PANI CE without doping. Doping with Cu^(2+)decreased the power conversion efficiency of PANI CE(PANI-Cu^(2+) η = 1.41%). The electrical properties of the PANI, PANI-Ni^(2+), PANI-Co^(2+),PANI-Mn^(2+) and PANI-Cu^(2+) were studied by cyclic voltammetry(CV), impedance(EIS), and Tafel polarization curve. The experimental results confirmed that PANI was affected by the doping of different transition metal ions(M^(2+)=Mn^(2+),Ni^(2+),Co^(2+),Cu^(2+)). These results indicate a potential application of ion doped PANI as counter electrode in cost-effective DSSCs.展开更多
An attempt has been made to explore whether the power relation can be obtained from theoretical considerations. The classical laminar and turbulent boundary layer concepts have been employed to determine appropriate v...An attempt has been made to explore whether the power relation can be obtained from theoretical considerations. The classical laminar and turbulent boundary layer concepts have been employed to determine appropriate values of the scaling lengths associated with vortex shedding and shear layer frequencies to predict the power law relationship with Reynolds number. The predicted results are in good agreement with experimental results. The findings will provide a greater insight into the overall phenomenon involved.展开更多
Under the pressure of environmental issues,decarbonization of the entire energy system has emerged as a prevalent strategy worldwide.The evolution of China’s power system will increasingly emphasize the integration o...Under the pressure of environmental issues,decarbonization of the entire energy system has emerged as a prevalent strategy worldwide.The evolution of China’s power system will increasingly emphasize the integration of variable renewable energy(VRE).However,the rapid growth of VRE will pose substantial challenges to the power system,highlighting the importance of power system planning.This letter introduces Grid Optimal Planning Tool(GOPT),a planning tool,and presents the key findings of our research utilizing GOPT to analyze the transition pathway of China’s power system towards dual carbon goals.Furthermore,the letter offers insights into key technologies essential for driving the future transition of China’s power system.展开更多
With high carbon emission,the low-carbon transition of power sector will be critical for China to achieve the carbon peaking and carbon neutrality goals.The power transition will have an impact on the economy and empl...With high carbon emission,the low-carbon transition of power sector will be critical for China to achieve the carbon peaking and carbon neutrality goals.The power transition will have an impact on the economy and employment through the value chain.Quantifying the impact is important for China's future energy and welfare policies.This study adopts input‒output model to analyze the impact on economy and employment based on accelerated and slow power transition scenarios.The results show that the low-carbon power transition will have a negative impact on coal power and coal mining and washing sectors,while a positive impact on machine manufacturing and equipment sector.Low-carbon power transition will have a positive economic and employment effect to promote inclusive growth.By 2060,economic output will increase by about 8.50 trillion CNY,value-added by about 3.39 trillion CNY,and employment will increase by about 3.74 million.Although slower coal power transition can stabilize the economic and employment effect in the short and medium run,accelerating the power transition will produce more positive effect and lower job losses by coal power in the long run.By 2060,accelerating transition will boost output by 8.21%,value-added by 8.20%and jobs by 7.97%.Accordingly,the government should establish an all-round just low-carbon transition mechanism.展开更多
This paper goes beyond Sino-Nordic Arctic science diplomacy and looks at Sino-Nordic Arctic triple-helix knowledge- based collaborations among academia, business, civil society （the inclusion of which moves beyond th...This paper goes beyond Sino-Nordic Arctic science diplomacy and looks at Sino-Nordic Arctic triple-helix knowledge- based collaborations among academia, business, civil society （the inclusion of which moves beyond the original triple-helix concept）, and government. In light of the potential of science diplomacy for building Sino-Arctic trust under systemic international conditions of power transition and globalization, this is the natural next step toward exploring triple-helix collaborations. Knowledge-based collaborations between academia, business, civil society, and government also open up avenues for innovation and entrepreneurship by both Arctic societies and Chinese society in attempts to address major challenges to sustainable development in these societies. This paper discusses possible triple-helix knowledge-based collaborations with China by each of the five Nordic countries, and highlights the innovation and entrepreneurial talents of summer school students at the University of International Relations in Beijing in developing projects as part of a course entitled ＂The Global Arctic＂.展开更多
As the world seeks to increase ambition rapidly to limit global warming to 1.5℃,joint leadership from the world's largest greenhouse gas(GHG)emitters-the United States(U.S.)and China-will be critical to deliver s...As the world seeks to increase ambition rapidly to limit global warming to 1.5℃,joint leadership from the world's largest greenhouse gas(GHG)emitters-the United States(U.S.)and China-will be critical to deliver significant emissions reductions from their own countries as well as to catalyze increased international action.After a period of uncertainty in international climate policy,these countries now both have current leadership that supports ambitious climate action.In this context,a feasible,high-impact,and potentially globally catalytic agreement by the U.S.and China to transition away from coal to clean energy would be a major contribution toward this global effort.We undertake a plant-by-plant assessment in the power sector to identify practical coal retirement pathways for each country that are in line with national priorities and the global 1.5℃ target.Our plant-by-plant analysis shows that the 1.5℃-compatible pathways may result in an average retirement age of 47 years for the U.S.coal plants and 22 years for Chinese coal plants,raising important questions of how to compare broader economic,employment,and social impacts.We also demonstrate that such pathways would also lead to significant emissions reductions,lowering overall global energy-related CO_(2) emissions by about 9%in 2030 relative to 2020.A catalytic effect from the possibility of other countries taking compatible actions is estimated to reduce global emissions by 5.1 Gt CO_(2) in 2030 and by 10.1 Gt CO_(2) in 2045.展开更多
Pressure fluctuations signals of a lab-scale fiuidized bed （15 cm inner diameter and 2 m height） at different superficial gas velocities were measured. Recurrence plot （RP） and recurrence rate （RR）, and the simp...Pressure fluctuations signals of a lab-scale fiuidized bed （15 cm inner diameter and 2 m height） at different superficial gas velocities were measured. Recurrence plot （RP） and recurrence rate （RR）, and the simplest variable of recurrence quantification analysis （RQA） were used to analyze the pressure signals. Different patterns observed in RP reflect different dynamic behavior of the system under study. It was also found that the variance of RR （a2R） Could reveal the peak dominant frequencies （PDF） of different dynamic systems： completely periodic, completely stochastic, Lorenz system, and fluidized bed. The results were compared with power spectral density. Additionally, the diagram of σ^2RR provides a new technique for prediction of transition velocity from bubbling to turbulent fluidization regime.展开更多
文摘The world is facing the third important global power shift.The United States,EU, Japan,Russia,China,and the newly emerging power group are becoming the six big forces in the international center stage,while the former three forces and the latter three belong to two groups,waning and waxing respectively.The major shift in the global balance of power is bound to give rise to the transitional multi-polar configuration,which implies a shifting of leadership over the configuration,China and U.S.outweighing other forces,global issues looming large,homogeneity blending with heterogeneity,and a shifting center of world powers.The transitional multi-polar configuration is all about change,upon which China is one of the decisive forces.
文摘The use of an electrical network as close as possible to its limits can lead to its instability in the event of a high amplitude disturbance. The damping of system oscillations can be achieved by conventional means of voltage and speed regulation but also by FACTS (Flexible AC Transmission Systems) devices, which are increasingly used in power networks. In this work, optimal control coordination between a hybrid power flow controller and a three-level inverter was used to improve the transient stability of a transmission line. The UPFC is a combination of a serial compensator (SSSC) and a parallel compensator (STATCOM) both connected to a DC-LINK DC bus. The SSSC acts as a voltage source for the network and injects a voltage that can be adjusted in phase and amplitude in addition to the network voltage;the STATCOM acts as a current source. The approach used is tested in the Matlab Simulink environment on a single machine network. Optimal controller tuning gives a better transient stability improvement by reducing the transport angle oscillations from 248.17% to 9.85%.
基金Supported by the National Natural Science Foundation of China(21473048,21303039)the Natural Science Foundation of Hebei Province(B2016205161,B2015205163)the 2015 Hebei Province Undergraduate Training Programs for Innovation and Entrepreneurship
文摘The effect of transition metal ions(M^(2+)=Mn^(2+),Ni^(2+),Co^(2+),Cu^(2+)) on the chemical synthesis of polyaniline(PANI) used as a platinum-free counter electrode(CE) in dye-sensitized solar cells(DSSCs) was investigated.PANI was synthesized by co-polymerization of aniline in the presence of different transition metal ions by using potassium dichromate in acidic medium. It was found that the ion doping of PANI showed a certain catalytic activity for the regeneration of traditional iodide/triiodide(I^-/I_3^-) redox couples. The power conversion efficiency(η) of PANI CEs doped with Mn^(2+),Ni^(2+),Co^(2+) (4.41%, 2.36% and 2.10%, respectively) were higher than 1.94%, the value measured for PANI CE without doping. Doping with Cu^(2+)decreased the power conversion efficiency of PANI CE(PANI-Cu^(2+) η = 1.41%). The electrical properties of the PANI, PANI-Ni^(2+), PANI-Co^(2+),PANI-Mn^(2+) and PANI-Cu^(2+) were studied by cyclic voltammetry(CV), impedance(EIS), and Tafel polarization curve. The experimental results confirmed that PANI was affected by the doping of different transition metal ions(M^(2+)=Mn^(2+),Ni^(2+),Co^(2+),Cu^(2+)). These results indicate a potential application of ion doped PANI as counter electrode in cost-effective DSSCs.
文摘An attempt has been made to explore whether the power relation can be obtained from theoretical considerations. The classical laminar and turbulent boundary layer concepts have been employed to determine appropriate values of the scaling lengths associated with vortex shedding and shear layer frequencies to predict the power law relationship with Reynolds number. The predicted results are in good agreement with experimental results. The findings will provide a greater insight into the overall phenomenon involved.
基金supported by the National Natural Science Foundation of China(No.52130702,No.52177093)。
文摘Under the pressure of environmental issues,decarbonization of the entire energy system has emerged as a prevalent strategy worldwide.The evolution of China’s power system will increasingly emphasize the integration of variable renewable energy(VRE).However,the rapid growth of VRE will pose substantial challenges to the power system,highlighting the importance of power system planning.This letter introduces Grid Optimal Planning Tool(GOPT),a planning tool,and presents the key findings of our research utilizing GOPT to analyze the transition pathway of China’s power system towards dual carbon goals.Furthermore,the letter offers insights into key technologies essential for driving the future transition of China’s power system.
基金funding of National Natural Science Foundation of China(72173043)Rockefeller Brothers Fund(21-200).
文摘With high carbon emission,the low-carbon transition of power sector will be critical for China to achieve the carbon peaking and carbon neutrality goals.The power transition will have an impact on the economy and employment through the value chain.Quantifying the impact is important for China's future energy and welfare policies.This study adopts input‒output model to analyze the impact on economy and employment based on accelerated and slow power transition scenarios.The results show that the low-carbon power transition will have a negative impact on coal power and coal mining and washing sectors,while a positive impact on machine manufacturing and equipment sector.Low-carbon power transition will have a positive economic and employment effect to promote inclusive growth.By 2060,economic output will increase by about 8.50 trillion CNY,value-added by about 3.39 trillion CNY,and employment will increase by about 3.74 million.Although slower coal power transition can stabilize the economic and employment effect in the short and medium run,accelerating the power transition will produce more positive effect and lower job losses by coal power in the long run.By 2060,accelerating transition will boost output by 8.21%,value-added by 8.20%and jobs by 7.97%.Accordingly,the government should establish an all-round just low-carbon transition mechanism.
基金China Nordic Arctic Research Center(Polar Research Institute of China)for providing me with a visiting fellowship from 1 March to 28 April,2016funding from the Department of Sociology,Political Science and Community Planning,and the HSL-utdanningsfond(Faculty of Humanities,Social Sciences and Education Teaching Fund),University of Tromso-The Arctic University of Norway,to attend the China-Nordic Arctic Cooperation Symposium in Rovaniemi from 6 to 9 June,2016
文摘This paper goes beyond Sino-Nordic Arctic science diplomacy and looks at Sino-Nordic Arctic triple-helix knowledge- based collaborations among academia, business, civil society （the inclusion of which moves beyond the original triple-helix concept）, and government. In light of the potential of science diplomacy for building Sino-Arctic trust under systemic international conditions of power transition and globalization, this is the natural next step toward exploring triple-helix collaborations. Knowledge-based collaborations between academia, business, civil society, and government also open up avenues for innovation and entrepreneurship by both Arctic societies and Chinese society in attempts to address major challenges to sustainable development in these societies. This paper discusses possible triple-helix knowledge-based collaborations with China by each of the five Nordic countries, and highlights the innovation and entrepreneurial talents of summer school students at the University of International Relations in Beijing in developing projects as part of a course entitled ＂The Global Arctic＂.
基金RC,NH,DC,LC,HM acknowledge funding support from Bloomberg Philanthropies,USA and Climate Works Foundation,USAJH Yuan acknowledges the funding of National Natural Science Foundation of China(72173043)+1 种基金WJ Cai acknowledges the funding of National Natural Science Foundation of China(71773061)the GEIGC Science and Technology Project in the framework of the“Research on Comprehensive Path Evaluation Methods and Practical Models for the Synergetic Development of Global Energy,Atmospheric Environment and Human Health”(grant No.20210302007).
文摘As the world seeks to increase ambition rapidly to limit global warming to 1.5℃,joint leadership from the world's largest greenhouse gas(GHG)emitters-the United States(U.S.)and China-will be critical to deliver significant emissions reductions from their own countries as well as to catalyze increased international action.After a period of uncertainty in international climate policy,these countries now both have current leadership that supports ambitious climate action.In this context,a feasible,high-impact,and potentially globally catalytic agreement by the U.S.and China to transition away from coal to clean energy would be a major contribution toward this global effort.We undertake a plant-by-plant assessment in the power sector to identify practical coal retirement pathways for each country that are in line with national priorities and the global 1.5℃ target.Our plant-by-plant analysis shows that the 1.5℃-compatible pathways may result in an average retirement age of 47 years for the U.S.coal plants and 22 years for Chinese coal plants,raising important questions of how to compare broader economic,employment,and social impacts.We also demonstrate that such pathways would also lead to significant emissions reductions,lowering overall global energy-related CO_(2) emissions by about 9%in 2030 relative to 2020.A catalytic effect from the possibility of other countries taking compatible actions is estimated to reduce global emissions by 5.1 Gt CO_(2) in 2030 and by 10.1 Gt CO_(2) in 2045.
基金Supports from the Iran National Science Foundation(INSF) in lran(No.91001766)
文摘Pressure fluctuations signals of a lab-scale fiuidized bed （15 cm inner diameter and 2 m height） at different superficial gas velocities were measured. Recurrence plot （RP） and recurrence rate （RR）, and the simplest variable of recurrence quantification analysis （RQA） were used to analyze the pressure signals. Different patterns observed in RP reflect different dynamic behavior of the system under study. It was also found that the variance of RR （a2R） Could reveal the peak dominant frequencies （PDF） of different dynamic systems： completely periodic, completely stochastic, Lorenz system, and fluidized bed. The results were compared with power spectral density. Additionally, the diagram of σ^2RR provides a new technique for prediction of transition velocity from bubbling to turbulent fluidization regime.
