This paper focuses on how to determine the instantaneous damping of the semi-active tuned mass damper (SATMD) with continuously variable damping.An off-and-towards-equilibrium (OTE) algorithm is employed to examine th...This paper focuses on how to determine the instantaneous damping of the semi-active tuned mass damper (SATMD) with continuously variable damping.An off-and-towards-equilibrium (OTE) algorithm is employed to examine the control performance of the structure/SATMD system by considering the damping as an assumptive control action.The damping modification of the SATMD is carried out according to the proposed OTE algorithm,which is formulated based on analysis of the structural movement under external excitations,and the measured responses of the structure at every time instant. As examples two numerical simulations of a five-storey and a ten-storey shear structures with a SATMD on the roof are conducted.The effectiveness on vibration reduction of MDOF systems subjected to seismic excitations is discussed.Analysis results show that the behavior of the structure with a SATMD is significantly improved and the feasibility of applying the OTE algorithm to the structural control design of SATMD is also verified.展开更多
The basic principle of particle image velocinmetry (PIV) is described. When a PIV image is analyzed by the method of auto-correlation, there is a direction ambiguity of 180 degrees iii velocity measurement. The proble...The basic principle of particle image velocinmetry (PIV) is described. When a PIV image is analyzed by the method of auto-correlation, there is a direction ambiguity of 180 degrees iii velocity measurement. The problem can be solved by using 'Image Shifting Technique', but this makes devices much complicated and difficult to control. A new arrangement of 2-CCD (Charge Coupled Device) fully digitized PIV system, which can also solve the problem successfully, is introduced in the paper. As an example of application of the system, an experimental result of flow field around a horizontal cylinder in wave is presented.展开更多
As China opens wider to the outside world, excess liquidity has become an outstanding issue in economic operations. This paper holds that China's liquidity is relatively excessive at the present time, and such exc...As China opens wider to the outside world, excess liquidity has become an outstanding issue in economic operations. This paper holds that China's liquidity is relatively excessive at the present time, and such excess liquidity is a reflection of domestic and foreign economic contradictions on the monetary level. Excess liquidity will pose a potential hazard to macroeconomic operation, and a multi-pronged approach should be taken to curb and control its sources at home and abroad.展开更多
The main goal of the fire management strategy is to avoid people interaction with fire hazards,therefore several studies are carried out for optimal escape route planning as well as smoke management and mechanical ven...The main goal of the fire management strategy is to avoid people interaction with fire hazards,therefore several studies are carried out for optimal escape route planning as well as smoke management and mechanical ventilation design.Underground spaces are a special case of study due to their technical characteristics that create different fire spread conditions compared to conventional buildings.In this paper,a comparative study on the fire smoke propagation is carried out taking into account the use and performance of smoke mitiga-tion techniques.The Underground Hazardous Waste Management Repository of Lavrion Technological and Cultural Park in Greece,is selected as a case study to achieve the paper objectives.A Computer Fluid Dynamic software is used to simulate various fire scenarios based on the specific characteristics of the underground space.Parameters that have significant impact on evacuation procedure and human health such as visibility and carbon monoxide concentration are monitored.Finally,the results are presented and an evaluation method is proposed based on evacuation simulation results,in order to predict the impact of the smoke control design on the conditions inside the underground space.The results reveal that the ventilation shaft(passive system)offers an effective smoke control without any other combined control system and that the installation of smoke curtains,which are activated on time,offers significant improvement on smoke spread control extending the available egress time(ASET)in case of fire.展开更多
Beam-column or beam-wall connections are an important problem in high-rise buildings. In this study, based on the analysis of an example structure, an analytical model for design of the semi-rigid connections between ...Beam-column or beam-wall connections are an important problem in high-rise buildings. In this study, based on the analysis of an example structure, an analytical model for design of the semi-rigid connections between steel beams and RC walls in high-rise hybrid buildings is proposed. Also, the mechanical characteristics of these connections subjected to low-reversed cyclic loading are investigated through comparison of experimental results from three semi-rigid connections and two rigid connections. Moreover, some latent problems for design of these connections as well as the corresponding solutions are discussed. The results from the experiments and analyses indicate that semi-rigid connections exhibit satisfactory capacity and seismic performance, and the proposed design can be used in practice.展开更多
Adjustment of Basle Capital Agreement will influence the risk management and capital arrangement demand of the banks with different scales, operation level and environment. It will have widespread and profound effect ...Adjustment of Basle Capital Agreement will influence the risk management and capital arrangement demand of the banks with different scales, operation level and environment. It will have widespread and profound effect on the competition strength of every country＇s banks in the global market. Starting with illustration of the present cond（tion of risk management in China＇s banks, the paper analyzes the major problems existing in the risk management system of China＇s banking industry, then puts forward some clues and suggestions to improve and better the risk management system of China＇s banking industry.展开更多
The outstanding properties of CVD diamond film such as electronic, optical, thermal and mechanical and the high radiation hardness have made it an ideal candidate material for radiation detectors in severe environment...The outstanding properties of CVD diamond film such as electronic, optical, thermal and mechanical and the high radiation hardness have made it an ideal candidate material for radiation detectors in severe environments. Fabrication of ＇detector grade＇ CVD diamond films and development of CVD diamond detectors have been leading edge subjects. Micro-strip gas chamber （MSGC） fabricated on CVD diamond substrate would overcome the charge-up effect and the substrate instability, which has been a hotspot in the research of gas detectors.展开更多
By using GARCH and EGARCH models, the authors examine the relationship between price volatility and new information flow, represented by trading volume, and past information flow, represented by the ARCH effect, in th...By using GARCH and EGARCH models, the authors examine the relationship between price volatility and new information flow, represented by trading volume, and past information flow, represented by the ARCH effect, in the Shanghai Stock Market for the three different periods from July 1998 to December 2002: the soft period, the bull period, and the bear period. The empirical results show that: (1) there exists a 'leverage effect' in the stock market; that is, negative news had a greater impact on stock price volatility than did positive news in the soft period and bear period, but in the bull period the 'leverage effect' behaves differently； (2) there is a significantly positive relationship between trading volume and stock price volatility, and such a relationship is even more significant in the bear period; (3) it turns out that in the three periods, the relationships between stock price volatility and information flow, both past and new, are not the same; that is, in both the soft and bull periods, both the ARCH effect, reflecting 'past information flow', and trading volume,reflecting 'new information flow', explain price volatility simultaneously, but in the bear period, the ARCH effect is substantially reduced. These findings provide key evidence for understanding, explaining, and tracking the characteristics of price volatility and the changing rules of the stock market in China more comprehensively.展开更多
Neural networks are being used to construct meta-models in numerical simulation of structures.In addition to network structures and training algorithms,training samples also greatly affect the accuracy of neural netwo...Neural networks are being used to construct meta-models in numerical simulation of structures.In addition to network structures and training algorithms,training samples also greatly affect the accuracy of neural network models.In this paper,some existing main sampling techniques are evaluated,including techniques based on experimental design theory, random selection,and rotating sampling.First,advantages and disadvantages of each technique are reviewed.Then,seven techniques are used to generate samples for training radial neural networks models for two benchmarks:an antenna model and an aircraft model.Results show that the uniform design,in which the number of samples and mean square error network models are considered,is the best sampling technique for neural network based meta-model building.展开更多
Monte Carlo simulations are an accurate but computationally expensive procedure for approximating the resultant non-Gaussian probability density function(PDF)after propagation of an initial Gaussian PDF through a nonl...Monte Carlo simulations are an accurate but computationally expensive procedure for approximating the resultant non-Gaussian probability density function(PDF)after propagation of an initial Gaussian PDF through a nonlinear function.Univariate splitting libraries for Gaussian Mixture Models(GMMs)exist with up to five elements in the literature.The number of splits are extended in the present work by generating three homoscedastic univariate splitting libraries with up to 39 elements.Mulitvariate GMMs are typically handled with splits along a single direction.Instead,we generate a regular multidirectional grid over the initial multivariate Gaussian distribution by recursively applying the splitting library along multiple directions.The splitting direction is arbitrary and no longer limited to directions parallel to the columns of the square-root of the covariance matrix.A second order Stirling’s interpolation of the nonlinear function evaluated at the mean of the initial Gaussian distribution is used to quantify nonlinearity along candidate splitting directions.The directions with the highest nonlinearity benefit most from splitting.The Multidirectional GMM(MGMM)has applications for uncertainty quantification with computationally intensive nonlinear functions.The variable number of splits in each direction allows for a spectrum of models in the accuracy versus compute time design space,filling the gap between expensive Monte Carlos and fast linearized models.The multidirectional method is demonstrated with four test cases,including an orbit uncertainty propagation case,to illustrate the benefit of splitting along multiple directions and of ranking the splitting directions.展开更多
Numerical simulation of complex flow fields with multi-scale structures is one of the most important and challenging branches of computational fluid dynamics. From linear analysis and numerical experiments it has been...Numerical simulation of complex flow fields with multi-scale structures is one of the most important and challenging branches of computational fluid dynamics. From linear analysis and numerical experiments it has been discovered that the higher-order accurate method can give reliable and efficient computational results, as well as better resolution of the complex flow fields with multi-scale structures. Compact finite difference schemes, which feature higher-order accuracy and spectral-like resolution with smaller stencils and easier application of boundary conditions, has attracted more and more interest and attention.展开更多
The paper analyzes the impact of U.S.direct investment in Chino on the Sino-US trade balance.The research shows that US FDI in China has largely widened the US-Chino trade deficit.On the one hand,cost-oriented US inve...The paper analyzes the impact of U.S.direct investment in Chino on the Sino-US trade balance.The research shows that US FDI in China has largely widened the US-Chino trade deficit.On the one hand,cost-oriented US investment enlarged Ch/nese export to the US;on the other hand,market-oriented investment decreased US exports to China.Moreover,China’s surplus against US high-technology products is mainly created by foreign invested enterprises.Therefore,the paper suggests that China should adjust its FDI policies to reduce the trade surplus against the US,thereby calming the trade dispute with the US as well as other countries.展开更多
This paper is a case study based on the privatization of Guoguang Ceramics.It is found that,contrary to the thoughts of some scholars, corporation performance actually deteriorated,rather than improved under privatiza...This paper is a case study based on the privatization of Guoguang Ceramics.It is found that,contrary to the thoughts of some scholars, corporation performance actually deteriorated,rather than improved under privatization.We analyze ownership arrangements before and after privatization and find that private ownership arrangements still have deficiencies and are not necessarily better than state ownership arrangements.The existence of private benefits of control is the essential reason why performance had been deteriorating.Private benefits of control under state ownership come from the government’s multiple objectives of corporation control,whereas the benefits with private ownership lie on resources transferred from the corporation.Ta succeed in privatizing SOEs,it is essential that legal systems be strengthened to effectively oversee private benefits of control.展开更多
文摘This paper focuses on how to determine the instantaneous damping of the semi-active tuned mass damper (SATMD) with continuously variable damping.An off-and-towards-equilibrium (OTE) algorithm is employed to examine the control performance of the structure/SATMD system by considering the damping as an assumptive control action.The damping modification of the SATMD is carried out according to the proposed OTE algorithm,which is formulated based on analysis of the structural movement under external excitations,and the measured responses of the structure at every time instant. As examples two numerical simulations of a five-storey and a ten-storey shear structures with a SATMD on the roof are conducted.The effectiveness on vibration reduction of MDOF systems subjected to seismic excitations is discussed.Analysis results show that the behavior of the structure with a SATMD is significantly improved and the feasibility of applying the OTE algorithm to the structural control design of SATMD is also verified.
基金This Project was financially supported by the National Science Foundation of China and British Council
文摘The basic principle of particle image velocinmetry (PIV) is described. When a PIV image is analyzed by the method of auto-correlation, there is a direction ambiguity of 180 degrees iii velocity measurement. The problem can be solved by using 'Image Shifting Technique', but this makes devices much complicated and difficult to control. A new arrangement of 2-CCD (Charge Coupled Device) fully digitized PIV system, which can also solve the problem successfully, is introduced in the paper. As an example of application of the system, an experimental result of flow field around a horizontal cylinder in wave is presented.
文摘As China opens wider to the outside world, excess liquidity has become an outstanding issue in economic operations. This paper holds that China's liquidity is relatively excessive at the present time, and such excess liquidity is a reflection of domestic and foreign economic contradictions on the monetary level. Excess liquidity will pose a potential hazard to macroeconomic operation, and a multi-pronged approach should be taken to curb and control its sources at home and abroad.
文摘The main goal of the fire management strategy is to avoid people interaction with fire hazards,therefore several studies are carried out for optimal escape route planning as well as smoke management and mechanical ventilation design.Underground spaces are a special case of study due to their technical characteristics that create different fire spread conditions compared to conventional buildings.In this paper,a comparative study on the fire smoke propagation is carried out taking into account the use and performance of smoke mitiga-tion techniques.The Underground Hazardous Waste Management Repository of Lavrion Technological and Cultural Park in Greece,is selected as a case study to achieve the paper objectives.A Computer Fluid Dynamic software is used to simulate various fire scenarios based on the specific characteristics of the underground space.Parameters that have significant impact on evacuation procedure and human health such as visibility and carbon monoxide concentration are monitored.Finally,the results are presented and an evaluation method is proposed based on evacuation simulation results,in order to predict the impact of the smoke control design on the conditions inside the underground space.The results reveal that the ventilation shaft(passive system)offers an effective smoke control without any other combined control system and that the installation of smoke curtains,which are activated on time,offers significant improvement on smoke spread control extending the available egress time(ASET)in case of fire.
基金National Natural Science Foundation of China Under Grant No. 50025821
文摘Beam-column or beam-wall connections are an important problem in high-rise buildings. In this study, based on the analysis of an example structure, an analytical model for design of the semi-rigid connections between steel beams and RC walls in high-rise hybrid buildings is proposed. Also, the mechanical characteristics of these connections subjected to low-reversed cyclic loading are investigated through comparison of experimental results from three semi-rigid connections and two rigid connections. Moreover, some latent problems for design of these connections as well as the corresponding solutions are discussed. The results from the experiments and analyses indicate that semi-rigid connections exhibit satisfactory capacity and seismic performance, and the proposed design can be used in practice.
文摘Adjustment of Basle Capital Agreement will influence the risk management and capital arrangement demand of the banks with different scales, operation level and environment. It will have widespread and profound effect on the competition strength of every country＇s banks in the global market. Starting with illustration of the present cond（tion of risk management in China＇s banks, the paper analyzes the major problems existing in the risk management system of China＇s banking industry, then puts forward some clues and suggestions to improve and better the risk management system of China＇s banking industry.
文摘The outstanding properties of CVD diamond film such as electronic, optical, thermal and mechanical and the high radiation hardness have made it an ideal candidate material for radiation detectors in severe environments. Fabrication of ＇detector grade＇ CVD diamond films and development of CVD diamond detectors have been leading edge subjects. Micro-strip gas chamber （MSGC） fabricated on CVD diamond substrate would overcome the charge-up effect and the substrate instability, which has been a hotspot in the research of gas detectors.
文摘By using GARCH and EGARCH models, the authors examine the relationship between price volatility and new information flow, represented by trading volume, and past information flow, represented by the ARCH effect, in the Shanghai Stock Market for the three different periods from July 1998 to December 2002: the soft period, the bull period, and the bear period. The empirical results show that: (1) there exists a 'leverage effect' in the stock market; that is, negative news had a greater impact on stock price volatility than did positive news in the soft period and bear period, but in the bull period the 'leverage effect' behaves differently； (2) there is a significantly positive relationship between trading volume and stock price volatility, and such a relationship is even more significant in the bear period; (3) it turns out that in the three periods, the relationships between stock price volatility and information flow, both past and new, are not the same; that is, in both the soft and bull periods, both the ARCH effect, reflecting 'past information flow', and trading volume,reflecting 'new information flow', explain price volatility simultaneously, but in the bear period, the ARCH effect is substantially reduced. These findings provide key evidence for understanding, explaining, and tracking the characteristics of price volatility and the changing rules of the stock market in China more comprehensively.
基金Specialized Research Fund for the Doctoral Program of Higher Education,China (No.20010227012)
文摘Neural networks are being used to construct meta-models in numerical simulation of structures.In addition to network structures and training algorithms,training samples also greatly affect the accuracy of neural network models.In this paper,some existing main sampling techniques are evaluated,including techniques based on experimental design theory, random selection,and rotating sampling.First,advantages and disadvantages of each technique are reviewed.Then,seven techniques are used to generate samples for training radial neural networks models for two benchmarks:an antenna model and an aircraft model.Results show that the uniform design,in which the number of samples and mean square error network models are considered,is the best sampling technique for neural network based meta-model building.
文摘Monte Carlo simulations are an accurate but computationally expensive procedure for approximating the resultant non-Gaussian probability density function(PDF)after propagation of an initial Gaussian PDF through a nonlinear function.Univariate splitting libraries for Gaussian Mixture Models(GMMs)exist with up to five elements in the literature.The number of splits are extended in the present work by generating three homoscedastic univariate splitting libraries with up to 39 elements.Mulitvariate GMMs are typically handled with splits along a single direction.Instead,we generate a regular multidirectional grid over the initial multivariate Gaussian distribution by recursively applying the splitting library along multiple directions.The splitting direction is arbitrary and no longer limited to directions parallel to the columns of the square-root of the covariance matrix.A second order Stirling’s interpolation of the nonlinear function evaluated at the mean of the initial Gaussian distribution is used to quantify nonlinearity along candidate splitting directions.The directions with the highest nonlinearity benefit most from splitting.The Multidirectional GMM(MGMM)has applications for uncertainty quantification with computationally intensive nonlinear functions.The variable number of splits in each direction allows for a spectrum of models in the accuracy versus compute time design space,filling the gap between expensive Monte Carlos and fast linearized models.The multidirectional method is demonstrated with four test cases,including an orbit uncertainty propagation case,to illustrate the benefit of splitting along multiple directions and of ranking the splitting directions.
文摘Numerical simulation of complex flow fields with multi-scale structures is one of the most important and challenging branches of computational fluid dynamics. From linear analysis and numerical experiments it has been discovered that the higher-order accurate method can give reliable and efficient computational results, as well as better resolution of the complex flow fields with multi-scale structures. Compact finite difference schemes, which feature higher-order accuracy and spectral-like resolution with smaller stencils and easier application of boundary conditions, has attracted more and more interest and attention.
文摘The paper analyzes the impact of U.S.direct investment in Chino on the Sino-US trade balance.The research shows that US FDI in China has largely widened the US-Chino trade deficit.On the one hand,cost-oriented US investment enlarged Ch/nese export to the US;on the other hand,market-oriented investment decreased US exports to China.Moreover,China’s surplus against US high-technology products is mainly created by foreign invested enterprises.Therefore,the paper suggests that China should adjust its FDI policies to reduce the trade surplus against the US,thereby calming the trade dispute with the US as well as other countries.
文摘This paper is a case study based on the privatization of Guoguang Ceramics.It is found that,contrary to the thoughts of some scholars, corporation performance actually deteriorated,rather than improved under privatization.We analyze ownership arrangements before and after privatization and find that private ownership arrangements still have deficiencies and are not necessarily better than state ownership arrangements.The existence of private benefits of control is the essential reason why performance had been deteriorating.Private benefits of control under state ownership come from the government’s multiple objectives of corporation control,whereas the benefits with private ownership lie on resources transferred from the corporation.Ta succeed in privatizing SOEs,it is essential that legal systems be strengthened to effectively oversee private benefits of control.
