The year of 2008 is the year of Olympic.The city of Beijing,being the host city for the game,implicates numerous potential business opportunities significantly,especially for the sporting goods industry. In china,due ...The year of 2008 is the year of Olympic.The city of Beijing,being the host city for the game,implicates numerous potential business opportunities significantly,especially for the sporting goods industry. In china,due to the abundant labor resources,market potentials and favorable policies,the sporting goods industry has developed markedly:within more than 50 years,it展开更多
Benba,38,is Director ofthe BorderTrade Bureau of the TibetAutonomous Region.Born andbrought up in Xigaze,he talkedabout booming border trade in Tibet duringmy recent interview.
Active attitude control of solar sails is required to control the direction of the force generated by Solar Radiation Pressure(SRP). It is desirable to control the attitude through propellantfree means. This paper pro...Active attitude control of solar sails is required to control the direction of the force generated by Solar Radiation Pressure(SRP). It is desirable to control the attitude through propellantfree means. This paper proposes a new method for attitude control of solar sails: A boom consisting of "smart" structural material can be deformed by the piezoelectric actuator, and Solar Radiation Pressure torque will be generated due to shape variation of sail membrane caused by boom deformation. The method has the advantages of simple structure, small disturbance and small additional load, and is not limited by the size of the solar sail. The case of rendezvous with the Asteroid 2000SG344 is used to verify the attitude control around the pitch and yaw axes.展开更多
Solar arrays are the primary energy source for spacecraft.Although traditional rigid solar arrays improve power supply,the quality increases proportionally.Hence,it is difficult to satisfy the requirements of high-pow...Solar arrays are the primary energy source for spacecraft.Although traditional rigid solar arrays improve power supply,the quality increases proportionally.Hence,it is difficult to satisfy the requirements of high-power and low-cost space applications.In this study,a shape-memory polymer composite(SMPC)boom was designed,fabricated,and characterized for flexible reel-type solar arrays.The SMPC boom was fabricated from a smart material,a shape-memory polymer composite,whose mechanical properties were tested.Additionally,a mathematical model of the bending stiffness of the SMPC boom was developed,and the bending and buckling behaviors of the boom were further analyzed using the ABAQUS software.An SMPC boom was fabricated to demonstrate its shape memory characteristics,and the driving force of the booms with varying geometric parameters was investigated.We also designed and manufactured a reel-type solar array based on an SMPC boom and verified its self-deployment capability.The results indicated that the SMPC boom can be used as a deployable unit to roll out flexible solar arrays.展开更多
The purpose of this paper is to demonstrate and investigate the concepts of new deployable boom systems, which consist of the BCON （braid coated bi-convex tape） boom and the SMA-BCON （braid coated bi-shape memory a...The purpose of this paper is to demonstrate and investigate the concepts of new deployable boom systems, which consist of the BCON （braid coated bi-convex tape） boom and the SMA-BCON （braid coated bi-shape memory alloy convex tape） boom. Both booms are developed for the deployable membrane structures such as solar sails, thin membrane solar array panels, deorbit mechanisms for small satellites and reflectors of space solar power satellite, etc. BCON booms can store around polygonal or cylindrical center hub, and the booms can deploy by the stepwise manner by releasing a constraint mechanism which pins the boons into two or three points for the total length. SMA-BCON booms are mainly developed for a square center body systems, and SMA is adapted on the bent po^nts of the booms where stored around each edge of the center hub. Through the deployment experiments of both booms, the stepwise deployment behavior and its tendency are obtained. The design concept of BCON boom and SMA-BCON hnnm i~ demonstrated through this study.展开更多
Incorporating asymmetric cost and benefit of supplying excess liquidity into an otherwise standard time inconsistency model this paper offers an explanation of the excess liquidity and housing price booms recently exp...Incorporating asymmetric cost and benefit of supplying excess liquidity into an otherwise standard time inconsistency model this paper offers an explanation of the excess liquidity and housing price booms recently experienced in China. We find that the central bank＇s incentive to stimulate eeonomie growth with excess liquidity fuels real estate prices and accelerates inflation bias. Therefore, the central bank should free itself from the pressure to achieve an economic growth rate higher than the potential level and assign an appropriate weight to the real estate price fluctuations in the central bank＇s objective function, so that the central bank ＂s policy of stimulating economic growth with excess liquidity can be constrained.展开更多
From August 14 to 16,the 52nd China Beijing International Gifts,Premium&Houseware Exhibition(hereinafter referred to as Beijing Gift&Home)was held at the China International Exhibition Center(Chaoyang Pavilion...From August 14 to 16,the 52nd China Beijing International Gifts,Premium&Houseware Exhibition(hereinafter referred to as Beijing Gift&Home)was held at the China International Exhibition Center(Chaoyang Pavilion)in Beijing,China.As the annual grand finale of the northern gift industry.展开更多
In order to reduce the ecological environmental pollution and economic losses caused by oil spill accidents from cross-river oil pipelines,this paper studies the structures of oil containment booms used for intercepti...In order to reduce the ecological environmental pollution and economic losses caused by oil spill accidents from cross-river oil pipelines,this paper studies the structures of oil containment booms used for intercepting oil spills in rapid rivers and proposes a new type of double-layer hole oil containment boom.By establishing a solid mechanics model,the geometric deformation and stress-strain distribution patterns of the double-layer hole oil containment boom under rapid flow velocities were analyzed.Additionally,the impact of the skirt angle,hole size,and porosity on themechanical properties of the newoil containment boomstructure was investigated,and the optimization range of the boom structure was determined.The results showed that,compared to the traditional single-layer oil containment boom,the optimized new boom reduced maximum tensile deformation by 91.1%and the maximum equivalent stress by 45.3%.Theresearch findings provide an effective reference for the rational design of oil containment booms in rapid rivers to ensure the safety of energy transportation and protect the ecological environment.展开更多
Although momentum strategies result in abnormal profitability,thereby challenging the efficient market hypothesis(EMH),concerns persist regarding their reliability due to their significant volatility and susceptibilit...Although momentum strategies result in abnormal profitability,thereby challenging the efficient market hypothesis(EMH),concerns persist regarding their reliability due to their significant volatility and susceptibility to substantial losses.In this study,we investigate the limitations of these strategies and propose a solution.Our literature review reveals that the volatile profits are due to statistical analyses that assume the persistence of past patterns,leading to unreliable results in out-of-sample scenarios when underlying mechanisms evolve.Statistical analysis,the predominant method in financial economics,often proves inadequate in explaining market fluctuations and predicting crashes.To overcome these limitations,a paradigm shift towards dynamic approaches is essential.Drawing inspiration from three groundbreaking economists,we introduce the extended Samuelson model(ESM),a dynamic model that connects price changes to market participant actions.This paradigm transition uncovers several significant findings.First,timely signals indicate momentum initiations,cessations,and reversals,validated using S&P 500 data from 1999 to 2023.Second,ESM predicts the 1987 Black Monday crash weeks in advance,offering a new perspective on its underlying cause.Third,we classify sequential stock price data into eight distinct market states,including their thresholds for transitions,laying the groundwork for market trend predictions and risk assessments.Fourth,the ESM is shown to be a compelling alternative to EMH,offering potent explanatory and predictive power based on a single,realistic assumption.Our findings suggest that ESM has the potential to provide policymakers with proactive tools,enabling financial institutions to enhance their risk assessment and management strategies.展开更多
文摘The year of 2008 is the year of Olympic.The city of Beijing,being the host city for the game,implicates numerous potential business opportunities significantly,especially for the sporting goods industry. In china,due to the abundant labor resources,market potentials and favorable policies,the sporting goods industry has developed markedly:within more than 50 years,it
文摘Benba,38,is Director ofthe BorderTrade Bureau of the TibetAutonomous Region.Born andbrought up in Xigaze,he talkedabout booming border trade in Tibet duringmy recent interview.
基金National Natural Science Foundation of China(Nos.11772167,11822205)。
文摘Active attitude control of solar sails is required to control the direction of the force generated by Solar Radiation Pressure(SRP). It is desirable to control the attitude through propellantfree means. This paper proposes a new method for attitude control of solar sails: A boom consisting of "smart" structural material can be deformed by the piezoelectric actuator, and Solar Radiation Pressure torque will be generated due to shape variation of sail membrane caused by boom deformation. The method has the advantages of simple structure, small disturbance and small additional load, and is not limited by the size of the solar sail. The case of rendezvous with the Asteroid 2000SG344 is used to verify the attitude control around the pitch and yaw axes.
基金Supported by National Natural Science Foundation of China(Grant Nos.52105013 and 51835002)Self-Planned Task of State Key Laboratory of Robotics and System(HIT)of China(Grant No.SKLRS202202C)China Postdoctoral Science Foundation(Grant No.2020M681087).
文摘Solar arrays are the primary energy source for spacecraft.Although traditional rigid solar arrays improve power supply,the quality increases proportionally.Hence,it is difficult to satisfy the requirements of high-power and low-cost space applications.In this study,a shape-memory polymer composite(SMPC)boom was designed,fabricated,and characterized for flexible reel-type solar arrays.The SMPC boom was fabricated from a smart material,a shape-memory polymer composite,whose mechanical properties were tested.Additionally,a mathematical model of the bending stiffness of the SMPC boom was developed,and the bending and buckling behaviors of the boom were further analyzed using the ABAQUS software.An SMPC boom was fabricated to demonstrate its shape memory characteristics,and the driving force of the booms with varying geometric parameters was investigated.We also designed and manufactured a reel-type solar array based on an SMPC boom and verified its self-deployment capability.The results indicated that the SMPC boom can be used as a deployable unit to roll out flexible solar arrays.
文摘The purpose of this paper is to demonstrate and investigate the concepts of new deployable boom systems, which consist of the BCON （braid coated bi-convex tape） boom and the SMA-BCON （braid coated bi-shape memory alloy convex tape） boom. Both booms are developed for the deployable membrane structures such as solar sails, thin membrane solar array panels, deorbit mechanisms for small satellites and reflectors of space solar power satellite, etc. BCON booms can store around polygonal or cylindrical center hub, and the booms can deploy by the stepwise manner by releasing a constraint mechanism which pins the boons into two or three points for the total length. SMA-BCON booms are mainly developed for a square center body systems, and SMA is adapted on the bent po^nts of the booms where stored around each edge of the center hub. Through the deployment experiments of both booms, the stepwise deployment behavior and its tendency are obtained. The design concept of BCON boom and SMA-BCON hnnm i~ demonstrated through this study.
文摘Incorporating asymmetric cost and benefit of supplying excess liquidity into an otherwise standard time inconsistency model this paper offers an explanation of the excess liquidity and housing price booms recently experienced in China. We find that the central bank＇s incentive to stimulate eeonomie growth with excess liquidity fuels real estate prices and accelerates inflation bias. Therefore, the central bank should free itself from the pressure to achieve an economic growth rate higher than the potential level and assign an appropriate weight to the real estate price fluctuations in the central bank＇s objective function, so that the central bank ＂s policy of stimulating economic growth with excess liquidity can be constrained.
文摘From August 14 to 16,the 52nd China Beijing International Gifts,Premium&Houseware Exhibition(hereinafter referred to as Beijing Gift&Home)was held at the China International Exhibition Center(Chaoyang Pavilion)in Beijing,China.As the annual grand finale of the northern gift industry.
文摘In order to reduce the ecological environmental pollution and economic losses caused by oil spill accidents from cross-river oil pipelines,this paper studies the structures of oil containment booms used for intercepting oil spills in rapid rivers and proposes a new type of double-layer hole oil containment boom.By establishing a solid mechanics model,the geometric deformation and stress-strain distribution patterns of the double-layer hole oil containment boom under rapid flow velocities were analyzed.Additionally,the impact of the skirt angle,hole size,and porosity on themechanical properties of the newoil containment boomstructure was investigated,and the optimization range of the boom structure was determined.The results showed that,compared to the traditional single-layer oil containment boom,the optimized new boom reduced maximum tensile deformation by 91.1%and the maximum equivalent stress by 45.3%.Theresearch findings provide an effective reference for the rational design of oil containment booms in rapid rivers to ensure the safety of energy transportation and protect the ecological environment.
文摘Although momentum strategies result in abnormal profitability,thereby challenging the efficient market hypothesis(EMH),concerns persist regarding their reliability due to their significant volatility and susceptibility to substantial losses.In this study,we investigate the limitations of these strategies and propose a solution.Our literature review reveals that the volatile profits are due to statistical analyses that assume the persistence of past patterns,leading to unreliable results in out-of-sample scenarios when underlying mechanisms evolve.Statistical analysis,the predominant method in financial economics,often proves inadequate in explaining market fluctuations and predicting crashes.To overcome these limitations,a paradigm shift towards dynamic approaches is essential.Drawing inspiration from three groundbreaking economists,we introduce the extended Samuelson model(ESM),a dynamic model that connects price changes to market participant actions.This paradigm transition uncovers several significant findings.First,timely signals indicate momentum initiations,cessations,and reversals,validated using S&P 500 data from 1999 to 2023.Second,ESM predicts the 1987 Black Monday crash weeks in advance,offering a new perspective on its underlying cause.Third,we classify sequential stock price data into eight distinct market states,including their thresholds for transitions,laying the groundwork for market trend predictions and risk assessments.Fourth,the ESM is shown to be a compelling alternative to EMH,offering potent explanatory and predictive power based on a single,realistic assumption.Our findings suggest that ESM has the potential to provide policymakers with proactive tools,enabling financial institutions to enhance their risk assessment and management strategies.
