Under the background of Sino-US trade friction,soybean,as an important variety in the important and export trade of agricultural products,has become a key bargaining chip. After the Ministry of Commerce of China annou...Under the background of Sino-US trade friction,soybean,as an important variety in the important and export trade of agricultural products,has become a key bargaining chip. After the Ministry of Commerce of China announced the counter list of agricultural products including soybean,the price fluctuations of domestic soybean and related agricultural products are rapidly expanding. Under the background of SinoUS trade friction,taking the soybean-producing areas in Heilongjiang as an example,the impact of Sino-US trade friction on the important and export pattern of soybean in Heilongjiang was explored to provide a certain theoretical basis for the development of soybean industry in Heilongjiang.展开更多
With the development of science and technology, informationization and economic globalization are developing faster and faster, and their impact on the world's economy and trade is also growing. The United States ...With the development of science and technology, informationization and economic globalization are developing faster and faster, and their impact on the world's economy and trade is also growing. The United States started the rebalancing strategy with tax reform as the starting point, and had large-scale trade frictions with China. How to avoid economic and trade frictions and promote sustainable economic development has become an important issue facing all countries. Although the economic and trade relations between the two countries are generally in a stable state, the friction in the trade field between the two countries exists in every stage of their economic and trade cooperation from beginning to end. The occurrence of trade friction not only affects the development of bilateral trade and regional economic development, but also may lead to a worldwide economic crisis. This paper analyzes the new forms of trade friction faced by the two countries under economic globalization through the friction between China and the United States in trade. With a view to promoting the sound development of trade between the two countries.展开更多
College English teaching in China has long been criticized for its orientation to examination that consequently brings about negative learning attitude and ineffective learning achievement.Chinese educationists have b...College English teaching in China has long been criticized for its orientation to examination that consequently brings about negative learning attitude and ineffective learning achievement.Chinese educationists have brought forward several ap proaches to solve this problem but little has been changed due to the cultural influences.This paper analyzes the roots of examoriented education system in China in perspective of culture by comparing the Sino-U.S.cultural elements in depth in tradition al culture,learning and teaching motivation,teacher-student relationship and learners'engagement in class.This paper finally poses two suggestions on how to change the current situation gradually:(1) Focus on the washback of evaluation system on edu cational concepts.(2) Transform the product-evaluation to process-evaluation gradually by standardizing the current evaluation approaches,especially the standards of process-evaluation.展开更多
An approach is proposed for modeling and anal- yses of rigid multibody systems with frictional translation joints and driving constraints. The geometric constraints of translational joints with small clearance are tre...An approach is proposed for modeling and anal- yses of rigid multibody systems with frictional translation joints and driving constraints. The geometric constraints of translational joints with small clearance are treated as bilat- eral constraints by neglecting the impact between sliders and guides. Firstly, the normal forces acting on sliders, the driv- ing constraint forces (or moments) and the constraint forces of smooth revolute joints are all described by complementary conditions. The frictional contacts are characterized by a set- valued force law of Coulomb's dry friction. Combined with the theory of the horizontal linear complementarity problem (HLCP), an event-driven scheme is used to detect the transi- tions of the contact situation between sliders and guides, and the stick-slip transitions of sliders, respectively. And then, all constraint forces in the system can be computed easily. Secondly, the dynamic equations of multibody systems are written at the acceleration-force level by the Lagrange multiplier technique, and the Baumgarte stabilization method is used to reduce the constraint drift. Finally, a numerical example is given to show some non-smooth dynamical behaviors of the studied system. The obtained results validate the feasibility of algorithm and the effect of constraint stabilization.展开更多
The elastic support/dry friction damper is a type of damper which is used for active vibration control in a rotor system.To establish the analytical model of this type of damper,a two-dimensional friction model-ball/p...The elastic support/dry friction damper is a type of damper which is used for active vibration control in a rotor system.To establish the analytical model of this type of damper,a two-dimensional friction model-ball/plate model was proposed.By using this ball/plate model,a dynamics model of rotor with elastic support/dry friction dampers was established and experimentally verified.Moreover,the damping performance of the elastic support/dry friction damper was studied numerically with respect to some variable parameters.The numerical study shows that the damping performance of the elastic support/dry friction damper is closely related to the stiffness distribution of the rotor-support system,the damper location,the pressing force between the moving and stationary disk,the friction coefficient,the tangential contact stiffness of the contact interface,and the stiffness of the stationary disk.In general,the damper should be located on an elastic support which has a large vibration amplitude in order to achieve a better damping performance,and the more vibration energy in this elastic support concentrates,the better performance of the damper will be.The larger the tangential contact stiffness of the contact interface,and the stiffness of the stationary disk are,the better performance of the damper will be.There will be an optimal value of the friction force at which the damper performs best.展开更多
This work studies a mathematical model describing the static process of contact between a piezoelectric body and a thermally-electrically conductive foundation. The behavior of the material is modeled with a thermo-el...This work studies a mathematical model describing the static process of contact between a piezoelectric body and a thermally-electrically conductive foundation. The behavior of the material is modeled with a thermo-electro-elastic constitutive law. The contact is described by Signorini's conditions and Tresca's friction law including the electrical and thermal conductivity conditions. A variational formulation of the model in the form of a coupled system for displacements, electric potential, and temperature is de- rived. Existence and uniqueness of the solution are proved using the results of variational inequalities and a fixed point theorem.展开更多
In this paper,we investigate the equilibrium stability of a Filippov-type system having multiple stick regions based upon a smooth and discontinuous(SD) oscillator with dry friction.The sets of equilibrium states of...In this paper,we investigate the equilibrium stability of a Filippov-type system having multiple stick regions based upon a smooth and discontinuous(SD) oscillator with dry friction.The sets of equilibrium states of the system are analyzed together with Coulomb friction conditions in both( f_n,f_s) and(x,˙x) planes.In the stability analysis,Lyapunov functions are constructed to derive the instability for the equilibrium set of the hyperbolic type and La Salle's invariance principle is employed to obtain the stability of the nonhyperbolic type.Analysis demonstrates the existence of a thick stable manifold and the interior stability of the hyperbolic equilibrium set due to the attractive sliding mode of the Filippov property,and also shows that the unstable manifolds of the hyperbolic-type are that of the endpoints with their saddle property.Numerical calculations show a good agreement with the theoretical analysis and an excellent efficien y of the approach for equilibrium states in this particular Filippov system.Furthermore,the equilibrium bifurcations are presented to demonstrate the transition between the smooth and the discontinuous regimes.展开更多
In the history of Chinese-American people-to-people exchange,the implementation of the China-U.S.Fulbright Program is surely a bright facet which should not be ignored.This program has been cultivating talents in the ...In the history of Chinese-American people-to-people exchange,the implementation of the China-U.S.Fulbright Program is surely a bright facet which should not be ignored.This program has been cultivating talents in the fields of social sciences and humanities for the two countries,promoting Sino-U.S.communications in the domains of education,academia and culture,and propelling the diffusion and advance of both Chinese and American cultures.The Fulbright Program in China still has certain limitations waiting to be improved,and one obvious problem is its coverage in China.To solve this problem,more Chinese higher education institutions should be included in the China-U.S.Fulbright Program,and the result would be the generation of immeasurable value for the prosperity of Sino-American people-to-people exchange and therefore the construction of the new model of major country relations between China and the United States.展开更多
The past two years have witnessed great fluctuations ininternational oil prices,and diplomatic efforts,both above andunder the table,by major powers around this issue.The currenttension in the war-threatened Iraq has ...The past two years have witnessed great fluctuations ininternational oil prices,and diplomatic efforts,both above andunder the table,by major powers around this issue.The currenttension in the war-threatened Iraq has added more uncertainties to thefuture world oil situation.Will the world oil supply and demand change?What impact would this exert on big powers’ oil strategy choices,geopolitics as well as world economy?What should China do in such asituation?To find the answers to these questions,at the invitation of theeditor of the Contemporary International Relations,seven experts fromChina Institute of Contemporary International Relations gathered to have adiscussion in early February this year.Naturally,they have differentviews over many issues.Still,we hope our readers would find theirdiscussion interesting.Following is the list of participants.展开更多
The wind stress acquired from European Centre for Medium-Range Weather Forecasts (ECMWF), National Centers for Environmental Prediction (NCEP) climate models and QSCAT satellite observations are analyzed by using ...The wind stress acquired from European Centre for Medium-Range Weather Forecasts (ECMWF), National Centers for Environmental Prediction (NCEP) climate models and QSCAT satellite observations are analyzed by using frequency-wavenumber spectrum method. The spectrum of two climate models, i.e., ECMWF and NCEP, is similar for both 10 m wind data and model output wind stress data, which indicates that both the climate models capture the key feature of wind stress. While the QSCAT wind stress data shows the similar characteristics with the two climate models in both spectrum domain and the spatial distribution, but with a factor of approximately 1.25 times larger than that of climate models in energy. These differences show the uncertainty in the different wind stress products, which inevitably cause the atmospheric faction torque uncertainties on solid Earth with a 60% departure in annual amplitude, and furtherly affect the precise estimation of the Earth's rotation.展开更多
The movement of lubricated fibres in a fibre assembly is investigated theoretically and aviscous sliding model of friction is proposed.Previous work and experimental results are discussedin relation to the model.Resul...The movement of lubricated fibres in a fibre assembly is investigated theoretically and aviscous sliding model of friction is proposed.Previous work and experimental results are discussedin relation to the model.Results of drawing experiments carried out on wool slivers are also pres-ented and discussed.展开更多
China applied for restoration of its status as the GATT founding member in1986. The country has made great endeavor in reducing customs duties, removing non-tariff barriers, enhancing protection of intellectual proper...China applied for restoration of its status as the GATT founding member in1986. The country has made great endeavor in reducing customs duties, removing non-tariff barriers, enhancing protection of intellectual property rights andservice trades, launching reform of the foreign trade regime, eliminating trade bar-riers and improving environment for foreign investment. Over the past 14 years,China has taken part in 26 relevant multilateral meetings and hundreds of bilateralnegotiations.展开更多
Savings rates are the biggest difference in the economic structures of China and the United States,the two most important countries in today’s global economy.China has the highest savings rate of any major country,wh...Savings rates are the biggest difference in the economic structures of China and the United States,the two most important countries in today’s global economy.China has the highest savings rate of any major country,while the United States,at the other end of the spectrum, has the lowest.This paper discusses the origin of this contrast and its far-reaching implications for two-way economic and trade ties.展开更多
Since confidence is fading and anxiety is increasing in the US,America’s China policy has become more radical. In the short term, the US has the upper hand and China is in a relatively passive position. In the medium...Since confidence is fading and anxiety is increasing in the US,America’s China policy has become more radical. In the short term, the US has the upper hand and China is in a relatively passive position. In the medium-and long-term, there will be more balance between them. This current strategic gambling between China and the US will be the major issue of international politics in the first half of the 21 st century and the most prominent external challenge China faces. China needs to make strategic adjustments but the gamble may be worthwhile in correcting imbalance in the international order and in the co-evolution of the two countries.展开更多
In this paper, a quantitative analysis of the opening quality in friction spinning and its main ef-fecting factors is first made. Upon this basis the Box-Hunter’s experimental design method is usedto establish the qu...In this paper, a quantitative analysis of the opening quality in friction spinning and its main ef-fecting factors is first made. Upon this basis the Box-Hunter’s experimental design method is usedto establish the quadratic regressional equations in terms of primary opening technologicalparameters and yarn quality for medium and fine count friction spinning. The results of analysisand discussion show that the proper choice of opening roller speed and its reasonable match withthe yarn count is singificant for ensuring the spinning quality index as well as reducing unevenness,thin and thick places of the yarn.展开更多
A dynamic contact problem for elastic-viscoplastic materials with thermal effects is investigated. The contact is bilateral, and the friction is modeled with Tresca's friction law with heat exchange. A variational fo...A dynamic contact problem for elastic-viscoplastic materials with thermal effects is investigated. The contact is bilateral, and the friction is modeled with Tresca's friction law with heat exchange. A variational formulation of the model is derived, and the existence of a unique weak solution is proved. The proofs are based on the classical result of nonlinear first order evolution inequalities, the equations with monotone operators, and the fixed point arguments. Finally, the continuous dependence of the solution on the friction yield limit is studied.展开更多
The study indicates that public-private partnerships (PPPs) can play "strategic", "practical", or "regulative" roles by making use of "instrumental", "institutional", and "normative" approaches in tackli...The study indicates that public-private partnerships (PPPs) can play "strategic", "practical", or "regulative" roles by making use of "instrumental", "institutional", and "normative" approaches in tackling political issues between countries. PPPs have often been discussed in studies of urban development, service provision, health care, and so on, but they have rarely been analyzed in terms of international relations and political problems on global environmental issues. This study takes an environmental problena---Sino-US energy and climate change cooperation--as a case study to inspect the possible roles and approaches of PPPs. Sino-US cooperation has been launched such as under the Strategic & Economic Dialogue (S&ED) by both administrations, which has significantly contributed to their reconciliation of domestic abatement policies in climate change, environmental protection, and energy. The establishment of schemes such as the Ten-Year Framework for Cooperation on Energy and Environment (TYF), the EcoPartnerships, and wide-ranging dialogues and initiatives on clean energy and clean vehicles, in which both public and private actors participate, are among the important approaches of facilitating bilateral cooperation. The study concludes that these schemes have played strategic and practical roles in strengthening the degree of mutual trust and in facilitating the progress of cooperation, although more investigations are needed to considerate their regulative roles. The application of instrumental, institutional, and normative approaches have been observed through the implementation of the TYF and EcoPartnerships.展开更多
基金Supported by Tianjin Third National Agricultural Census Project (TJ2016NP023)
文摘Under the background of Sino-US trade friction,soybean,as an important variety in the important and export trade of agricultural products,has become a key bargaining chip. After the Ministry of Commerce of China announced the counter list of agricultural products including soybean,the price fluctuations of domestic soybean and related agricultural products are rapidly expanding. Under the background of SinoUS trade friction,taking the soybean-producing areas in Heilongjiang as an example,the impact of Sino-US trade friction on the important and export pattern of soybean in Heilongjiang was explored to provide a certain theoretical basis for the development of soybean industry in Heilongjiang.
文摘With the development of science and technology, informationization and economic globalization are developing faster and faster, and their impact on the world's economy and trade is also growing. The United States started the rebalancing strategy with tax reform as the starting point, and had large-scale trade frictions with China. How to avoid economic and trade frictions and promote sustainable economic development has become an important issue facing all countries. Although the economic and trade relations between the two countries are generally in a stable state, the friction in the trade field between the two countries exists in every stage of their economic and trade cooperation from beginning to end. The occurrence of trade friction not only affects the development of bilateral trade and regional economic development, but also may lead to a worldwide economic crisis. This paper analyzes the new forms of trade friction faced by the two countries under economic globalization through the friction between China and the United States in trade. With a view to promoting the sound development of trade between the two countries.
文摘College English teaching in China has long been criticized for its orientation to examination that consequently brings about negative learning attitude and ineffective learning achievement.Chinese educationists have brought forward several ap proaches to solve this problem but little has been changed due to the cultural influences.This paper analyzes the roots of examoriented education system in China in perspective of culture by comparing the Sino-U.S.cultural elements in depth in tradition al culture,learning and teaching motivation,teacher-student relationship and learners'engagement in class.This paper finally poses two suggestions on how to change the current situation gradually:(1) Focus on the washback of evaluation system on edu cational concepts.(2) Transform the product-evaluation to process-evaluation gradually by standardizing the current evaluation approaches,especially the standards of process-evaluation.
基金supported by the National Natural Science Foundation of China(11372018 and 11172019)
文摘An approach is proposed for modeling and anal- yses of rigid multibody systems with frictional translation joints and driving constraints. The geometric constraints of translational joints with small clearance are treated as bilat- eral constraints by neglecting the impact between sliders and guides. Firstly, the normal forces acting on sliders, the driv- ing constraint forces (or moments) and the constraint forces of smooth revolute joints are all described by complementary conditions. The frictional contacts are characterized by a set- valued force law of Coulomb's dry friction. Combined with the theory of the horizontal linear complementarity problem (HLCP), an event-driven scheme is used to detect the transi- tions of the contact situation between sliders and guides, and the stick-slip transitions of sliders, respectively. And then, all constraint forces in the system can be computed easily. Secondly, the dynamic equations of multibody systems are written at the acceleration-force level by the Lagrange multiplier technique, and the Baumgarte stabilization method is used to reduce the constraint drift. Finally, a numerical example is given to show some non-smooth dynamical behaviors of the studied system. The obtained results validate the feasibility of algorithm and the effect of constraint stabilization.
基金supported by the National Natural Science Foundation of China(No.51405393)
文摘The elastic support/dry friction damper is a type of damper which is used for active vibration control in a rotor system.To establish the analytical model of this type of damper,a two-dimensional friction model-ball/plate model was proposed.By using this ball/plate model,a dynamics model of rotor with elastic support/dry friction dampers was established and experimentally verified.Moreover,the damping performance of the elastic support/dry friction damper was studied numerically with respect to some variable parameters.The numerical study shows that the damping performance of the elastic support/dry friction damper is closely related to the stiffness distribution of the rotor-support system,the damper location,the pressing force between the moving and stationary disk,the friction coefficient,the tangential contact stiffness of the contact interface,and the stiffness of the stationary disk.In general,the damper should be located on an elastic support which has a large vibration amplitude in order to achieve a better damping performance,and the more vibration energy in this elastic support concentrates,the better performance of the damper will be.The larger the tangential contact stiffness of the contact interface,and the stiffness of the stationary disk are,the better performance of the damper will be.There will be an optimal value of the friction force at which the damper performs best.
文摘This work studies a mathematical model describing the static process of contact between a piezoelectric body and a thermally-electrically conductive foundation. The behavior of the material is modeled with a thermo-electro-elastic constitutive law. The contact is described by Signorini's conditions and Tresca's friction law including the electrical and thermal conductivity conditions. A variational formulation of the model in the form of a coupled system for displacements, electric potential, and temperature is de- rived. Existence and uniqueness of the solution are proved using the results of variational inequalities and a fixed point theorem.
基金supported by the National Natural Science Foundation of China(Grant 11372082)the National Basic Research Program of China(Grant 2015CB057405)
文摘In this paper,we investigate the equilibrium stability of a Filippov-type system having multiple stick regions based upon a smooth and discontinuous(SD) oscillator with dry friction.The sets of equilibrium states of the system are analyzed together with Coulomb friction conditions in both( f_n,f_s) and(x,˙x) planes.In the stability analysis,Lyapunov functions are constructed to derive the instability for the equilibrium set of the hyperbolic type and La Salle's invariance principle is employed to obtain the stability of the nonhyperbolic type.Analysis demonstrates the existence of a thick stable manifold and the interior stability of the hyperbolic equilibrium set due to the attractive sliding mode of the Filippov property,and also shows that the unstable manifolds of the hyperbolic-type are that of the endpoints with their saddle property.Numerical calculations show a good agreement with the theoretical analysis and an excellent efficien y of the approach for equilibrium states in this particular Filippov system.Furthermore,the equilibrium bifurcations are presented to demonstrate the transition between the smooth and the discontinuous regimes.
文摘In the history of Chinese-American people-to-people exchange,the implementation of the China-U.S.Fulbright Program is surely a bright facet which should not be ignored.This program has been cultivating talents in the fields of social sciences and humanities for the two countries,promoting Sino-U.S.communications in the domains of education,academia and culture,and propelling the diffusion and advance of both Chinese and American cultures.The Fulbright Program in China still has certain limitations waiting to be improved,and one obvious problem is its coverage in China.To solve this problem,more Chinese higher education institutions should be included in the China-U.S.Fulbright Program,and the result would be the generation of immeasurable value for the prosperity of Sino-American people-to-people exchange and therefore the construction of the new model of major country relations between China and the United States.
文摘The past two years have witnessed great fluctuations ininternational oil prices,and diplomatic efforts,both above andunder the table,by major powers around this issue.The currenttension in the war-threatened Iraq has added more uncertainties to thefuture world oil situation.Will the world oil supply and demand change?What impact would this exert on big powers’ oil strategy choices,geopolitics as well as world economy?What should China do in such asituation?To find the answers to these questions,at the invitation of theeditor of the Contemporary International Relations,seven experts fromChina Institute of Contemporary International Relations gathered to have adiscussion in early February this year.Naturally,they have differentviews over many issues.Still,we hope our readers would find theirdiscussion interesting.Following is the list of participants.
基金supported by research projects of National Basic Research Program of China (2012CB957802)the National Natural Science Foundation of China (41321063, 41374087)Open Fund of the State Key Laboratory of Geodesy and Earth's Dynamics (2014-2-1-E)
文摘The wind stress acquired from European Centre for Medium-Range Weather Forecasts (ECMWF), National Centers for Environmental Prediction (NCEP) climate models and QSCAT satellite observations are analyzed by using frequency-wavenumber spectrum method. The spectrum of two climate models, i.e., ECMWF and NCEP, is similar for both 10 m wind data and model output wind stress data, which indicates that both the climate models capture the key feature of wind stress. While the QSCAT wind stress data shows the similar characteristics with the two climate models in both spectrum domain and the spatial distribution, but with a factor of approximately 1.25 times larger than that of climate models in energy. These differences show the uncertainty in the different wind stress products, which inevitably cause the atmospheric faction torque uncertainties on solid Earth with a 60% departure in annual amplitude, and furtherly affect the precise estimation of the Earth's rotation.
文摘The movement of lubricated fibres in a fibre assembly is investigated theoretically and aviscous sliding model of friction is proposed.Previous work and experimental results are discussedin relation to the model.Results of drawing experiments carried out on wool slivers are also pres-ented and discussed.
文摘China applied for restoration of its status as the GATT founding member in1986. The country has made great endeavor in reducing customs duties, removing non-tariff barriers, enhancing protection of intellectual property rights andservice trades, launching reform of the foreign trade regime, eliminating trade bar-riers and improving environment for foreign investment. Over the past 14 years,China has taken part in 26 relevant multilateral meetings and hundreds of bilateralnegotiations.
文摘Savings rates are the biggest difference in the economic structures of China and the United States,the two most important countries in today’s global economy.China has the highest savings rate of any major country,while the United States,at the other end of the spectrum, has the lowest.This paper discusses the origin of this contrast and its far-reaching implications for two-way economic and trade ties.
文摘Since confidence is fading and anxiety is increasing in the US,America’s China policy has become more radical. In the short term, the US has the upper hand and China is in a relatively passive position. In the medium-and long-term, there will be more balance between them. This current strategic gambling between China and the US will be the major issue of international politics in the first half of the 21 st century and the most prominent external challenge China faces. China needs to make strategic adjustments but the gamble may be worthwhile in correcting imbalance in the international order and in the co-evolution of the two countries.
文摘In this paper, a quantitative analysis of the opening quality in friction spinning and its main ef-fecting factors is first made. Upon this basis the Box-Hunter’s experimental design method is usedto establish the quadratic regressional equations in terms of primary opening technologicalparameters and yarn quality for medium and fine count friction spinning. The results of analysisand discussion show that the proper choice of opening roller speed and its reasonable match withthe yarn count is singificant for ensuring the spinning quality index as well as reducing unevenness,thin and thick places of the yarn.
文摘A dynamic contact problem for elastic-viscoplastic materials with thermal effects is investigated. The contact is bilateral, and the friction is modeled with Tresca's friction law with heat exchange. A variational formulation of the model is derived, and the existence of a unique weak solution is proved. The proofs are based on the classical result of nonlinear first order evolution inequalities, the equations with monotone operators, and the fixed point arguments. Finally, the continuous dependence of the solution on the friction yield limit is studied.
文摘The study indicates that public-private partnerships (PPPs) can play "strategic", "practical", or "regulative" roles by making use of "instrumental", "institutional", and "normative" approaches in tackling political issues between countries. PPPs have often been discussed in studies of urban development, service provision, health care, and so on, but they have rarely been analyzed in terms of international relations and political problems on global environmental issues. This study takes an environmental problena---Sino-US energy and climate change cooperation--as a case study to inspect the possible roles and approaches of PPPs. Sino-US cooperation has been launched such as under the Strategic & Economic Dialogue (S&ED) by both administrations, which has significantly contributed to their reconciliation of domestic abatement policies in climate change, environmental protection, and energy. The establishment of schemes such as the Ten-Year Framework for Cooperation on Energy and Environment (TYF), the EcoPartnerships, and wide-ranging dialogues and initiatives on clean energy and clean vehicles, in which both public and private actors participate, are among the important approaches of facilitating bilateral cooperation. The study concludes that these schemes have played strategic and practical roles in strengthening the degree of mutual trust and in facilitating the progress of cooperation, although more investigations are needed to considerate their regulative roles. The application of instrumental, institutional, and normative approaches have been observed through the implementation of the TYF and EcoPartnerships.