This paper explores the disposition effect, the tendency of investors to hold losing investments too long and sell winning investments too soon, by analyzing a unique data set that consists of the buying and selling p...This paper explores the disposition effect, the tendency of investors to hold losing investments too long and sell winning investments too soon, by analyzing a unique data set that consists of the buying and selling positions of open-end fund investors in China. Results show that investors' buying and selling behaviors are significantly affected by fund performance. The reasons that lie behind such results are mainly related to the non-persistence of fund performance. When fund performance is non-persistent, investors are not clear about the future returns on funds. So, investors, especially individual investors, would have to realize the profits on hand immediately. Meanwhile, fund investors are highly sensitive to fund age and loading fees, but not sensitive to management fees charged by funds when they buy or sell fund shares.展开更多
Microwave fracturing of rocks before mechanical breakage could improve the performance of mechanical excavators and reduce environmental impacts.Previous research focused on the microwave fracturing of intact rock blo...Microwave fracturing of rocks before mechanical breakage could improve the performance of mechanical excavators and reduce environmental impacts.Previous research focused on the microwave fracturing of intact rock blocks.By using an open-ended antenna,this paper investigates the effect of pre-existing joints on the microwave fracturing of the Singapore Bukit Timah granite blocks.The results show that the specimens are weakened in the manners of cracking,spalling,melting,or a combination of them.The crack number and the total crack length produced by microwave treatment of jointed rock blocks are slightly smaller than those in the intact rock blocks.The interaction between joints and microwave-induced cracks can be summarized into the following four patterns:(1)microwave-induced cracks become arrested so that the crack propagation is terminated;(2)microwave-induced cracks penetrate the joints and continue to propagate;(3)microwave-induced cracks become deflected along the joints;and(4)microwave-induced cracks propagate forward following the joints.The smaller the approach angle between the microwave-induced crack and the preexisting joint is,the more microwave-induced cracks tend to be arrested at the joint.Increasing the approach angle between the microwave-induced crack and the joint can increase the chance of microwave-induced crack penetrating the joint.The results also show that the smaller the distance is between the microwave radiation point and the joint,the easier it is for microwave-induced cracks to penetrate the joints;otherwise,the microwave-induced crack is more likely to be arrested at the pre-existing joint.展开更多
During the installation of a pipe pile,the soil around the pile will be squeezed out. This paper deals with this squeezing effect of open-ended pipe piles using the cylindrical cavity expansion theory. The characteris...During the installation of a pipe pile,the soil around the pile will be squeezed out. This paper deals with this squeezing effect of open-ended pipe piles using the cylindrical cavity expansion theory. The characteristics of soil with different tension and compression moduli and dilation are involved by applying the elastic theory with different moduli and logarithmic strain. The closed-form solutions of the radius of the plastic region,the displacement of the boundary between the plastic region and the elastic region and the expansion pressure on the external surface of the pipe piles are obtained. When obtaining these solutions,the soil plug in the open-ended pipe pile is considered by employing an incremental filling ratio to quantify the degree of soil plugging. Moreover,the effects of the ratio of tension and compression moduli,angle of dilation and incremental filling ratio on the radius of the plastic region and the expansion pressure on the external surface of the pipe pile are investigated. The parametric analyses show that it is necessary and important to consider the difference between the tension modulus and compression modulus,dilation angle and incremental filling ratio for studying the squeezing effect of open-ended pipe pile installation. It is concluded that the analytical solutions presented in this paper are suitable for studying the squeezing effect of open-ended pipe piles.展开更多
Compared with the traditional three-phase star connection winding,the open-end winding permanent magnet synchronous motor(OW-PMSM)system with a common direct current(DC)bus has a zero-sequence circuit,which makes the ...Compared with the traditional three-phase star connection winding,the open-end winding permanent magnet synchronous motor(OW-PMSM)system with a common direct current(DC)bus has a zero-sequence circuit,which makes the common-mode voltage and the back electromotive force(EMF)harmonic generated by the inverters produce the zero-sequence current in the zero-sequence circuit,and the zero-sequence current has great influence on the operation efficiency and stability of the motor control system.A zero-sequence current suppression strategy is presented based on model predictive current control for OW-PMSM.Through the mathematical model of OW-PMSM to establish the predictive model and the zero-sequence circuit model,the common-mode voltage under different voltage vector combinations is fully considered during vector selection and action time calculation.Then zero-sequence loop constraints are established,so as to suppress the zero-sequence current.In the end,the control strategy proposed in this paper is verified by simulation experiments.展开更多
The flawed engineering practice is considered the main factor that is affecting to the development quality of engineering postgraduates.Taking Foshan Base as an example,this paper has analyzed the operational pattern,...The flawed engineering practice is considered the main factor that is affecting to the development quality of engineering postgraduates.Taking Foshan Base as an example,this paper has analyzed the operational pattern,practice teaching model,and internal governance system of the open-ended base as a new system for engineering practice and proposed several suggestions for the reformation of engineering postgraduates based on the construction effect.展开更多
Large open-ended pipe pile has been found to be advantageous for use in transportation projects. The current design method, however, is not adequately developed. To close this practice gap, this paper first summarized...Large open-ended pipe pile has been found to be advantageous for use in transportation projects. The current design method, however, is not adequately developed. To close this practice gap, this paper first summarized different design methods for open-ended pipe piles in sandy soils. A major factor for all the design codes is to properly account for the formation and effects of soil plug. The comparison indicates that there is a large variation in the base capacity evaluation among different methods due to the complex behaviors of soil plug. To close the knowledge gap, discrete element method （DEM） was used to simulate the soil plugging process and provide insight on the plugging mechanism. The simulation results show that the arching effect significantly increases the internal unit shear resistance along pipe piles. The porosity distribution and particle contact force distribution from DEM model indicate a large stress concentration occurs at the bottom of the soil plug. Besides, nearly 90% of the plug resistance is provided by the bottom half portion of the soil column. The soil-pile friction coefficient has a significant effect on the magnitude of plug resistance, with the major transition occurred for friction coefficient between 0.3 and 0.4.展开更多
Objective: To design a new open-end intracranial hematoma drainage tube for clinical application. Methods: The newly developed device consists of two parts: the plunger and barrel.On one side, the barrel is bullet sha...Objective: To design a new open-end intracranial hematoma drainage tube for clinical application. Methods: The newly developed device consists of two parts: the plunger and barrel.On one side, the barrel is bullet shaped with an opening tip. The plunger is located in the middle cavity of the tube barrel and extended out at the open-end. It was designed for strengthening the tube barrel and for convenience in performing the drainage procedure. It can be used by inserting the drainage tube into the lesion and pulling out the plunger, whereby blood will forcefully rise up inside the barrel, providing a satisfactory outcome. It is made for effusion drainage purposes. During the procedure, the drainage tip is placed at the deepest part of the intracranial hematoma to completely drain the blood. Moreover, the plunger fits tightly in the tube, preventing leakage during the operation. With the use of the device, brain can be separated. In addition, the device can help reduce the risk of cerebral damage because of the small operating area. The barrel sidewall has matching opening holes bilaterally and equally for exchanging substances between the inner and outer parts.The overlapping ratio in each horizontal pair is around 1/3–1/2. Each pair on the opposite side will form a different pressure. Thus, the opening holes will not easily get blocked with blood clot. Results: Blood and accumulated liquid from the deepest part of the intracranial hematoma can be directly drawn through the drainage tube without damaging a large area. The tube does not get blocked easily and allows for complete removal of the hematoma. Conclusions: The device is asuitable instrument for clinical application.展开更多
In open-ended piles, inner friction is developed between inner pile shaf and the inner soil. Inner frictional resistance depends largely on the degree of soil plugging, which is influenced by many factors including pi...In open-ended piles, inner friction is developed between inner pile shaf and the inner soil. Inner frictional resistance depends largely on the degree of soil plugging, which is influenced by many factors including pile diameter, relative density and end conditions of piles. In this paper, effects of inner sleeves on inner frictional resistance are discussed. The experiments were conducted on a medium-dense sandy ground using laboratory-scale piles. It was observed that the piles penetrated under partially-plugged or unplugged state. The results suggest that inner fiictional resistance, Qin increases with sleeve height, l linearly and requires 2D （D is pile outer diameter） of l to produce a large as 50% of Qt by Qin （Qt is total resistance）. The results also indicate that bearing capacity increases with wall thickness at the pile tip, which can be attributed to the increase in annular area. The results also indicate that soil plug height is independent of sleeve height. The results also reveal that the penetration of straight piles is closer to unplugged state than the sleeved piles. The results of incremental filling ratio and plug length ratio also indicate that the degree of soil plugging is affected by the sleeve height.展开更多
文摘This paper explores the disposition effect, the tendency of investors to hold losing investments too long and sell winning investments too soon, by analyzing a unique data set that consists of the buying and selling positions of open-end fund investors in China. Results show that investors' buying and selling behaviors are significantly affected by fund performance. The reasons that lie behind such results are mainly related to the non-persistence of fund performance. When fund performance is non-persistent, investors are not clear about the future returns on funds. So, investors, especially individual investors, would have to realize the profits on hand immediately. Meanwhile, fund investors are highly sensitive to fund age and loading fees, but not sensitive to management fees charged by funds when they buy or sell fund shares.
基金Innovative and Entrepreneurial Team Program of Jiangsu Province,China,Grant/Award Number:JSSCTD202140Innovative and Entrepreneurial Doctor Program of Jiangsu Province,Grant/Award Number:KYCX20_0114National Natural Science Foundation of China,Grant/Award Numbers:41831281,52104121。
文摘Microwave fracturing of rocks before mechanical breakage could improve the performance of mechanical excavators and reduce environmental impacts.Previous research focused on the microwave fracturing of intact rock blocks.By using an open-ended antenna,this paper investigates the effect of pre-existing joints on the microwave fracturing of the Singapore Bukit Timah granite blocks.The results show that the specimens are weakened in the manners of cracking,spalling,melting,or a combination of them.The crack number and the total crack length produced by microwave treatment of jointed rock blocks are slightly smaller than those in the intact rock blocks.The interaction between joints and microwave-induced cracks can be summarized into the following four patterns:(1)microwave-induced cracks become arrested so that the crack propagation is terminated;(2)microwave-induced cracks penetrate the joints and continue to propagate;(3)microwave-induced cracks become deflected along the joints;and(4)microwave-induced cracks propagate forward following the joints.The smaller the approach angle between the microwave-induced crack and the preexisting joint is,the more microwave-induced cracks tend to be arrested at the joint.Increasing the approach angle between the microwave-induced crack and the joint can increase the chance of microwave-induced crack penetrating the joint.The results also show that the smaller the distance is between the microwave radiation point and the joint,the easier it is for microwave-induced cracks to penetrate the joints;otherwise,the microwave-induced crack is more likely to be arrested at the pre-existing joint.
文摘During the installation of a pipe pile,the soil around the pile will be squeezed out. This paper deals with this squeezing effect of open-ended pipe piles using the cylindrical cavity expansion theory. The characteristics of soil with different tension and compression moduli and dilation are involved by applying the elastic theory with different moduli and logarithmic strain. The closed-form solutions of the radius of the plastic region,the displacement of the boundary between the plastic region and the elastic region and the expansion pressure on the external surface of the pipe piles are obtained. When obtaining these solutions,the soil plug in the open-ended pipe pile is considered by employing an incremental filling ratio to quantify the degree of soil plugging. Moreover,the effects of the ratio of tension and compression moduli,angle of dilation and incremental filling ratio on the radius of the plastic region and the expansion pressure on the external surface of the pipe pile are investigated. The parametric analyses show that it is necessary and important to consider the difference between the tension modulus and compression modulus,dilation angle and incremental filling ratio for studying the squeezing effect of open-ended pipe pile installation. It is concluded that the analytical solutions presented in this paper are suitable for studying the squeezing effect of open-ended pipe piles.
基金Fundamental Research Funds for the Central Universities,China(No.2232019D3-53)Initial Research Funds for Young Teachers of Donghua University,China(104070053029)Shanghai Rising-Star Program,China(No.19QA1400400)。
文摘Compared with the traditional three-phase star connection winding,the open-end winding permanent magnet synchronous motor(OW-PMSM)system with a common direct current(DC)bus has a zero-sequence circuit,which makes the common-mode voltage and the back electromotive force(EMF)harmonic generated by the inverters produce the zero-sequence current in the zero-sequence circuit,and the zero-sequence current has great influence on the operation efficiency and stability of the motor control system.A zero-sequence current suppression strategy is presented based on model predictive current control for OW-PMSM.Through the mathematical model of OW-PMSM to establish the predictive model and the zero-sequence circuit model,the common-mode voltage under different voltage vector combinations is fully considered during vector selection and action time calculation.Then zero-sequence loop constraints are established,so as to suppress the zero-sequence current.In the end,the control strategy proposed in this paper is verified by simulation experiments.
基金supported by Guangdong Province Graduate Education Innovation Program(2021JGXM103)the 2020“Research on Talents”Project by the Guangdong Planning Office of Philosophy and Social Science.
文摘The flawed engineering practice is considered the main factor that is affecting to the development quality of engineering postgraduates.Taking Foshan Base as an example,this paper has analyzed the operational pattern,practice teaching model,and internal governance system of the open-ended base as a new system for engineering practice and proposed several suggestions for the reformation of engineering postgraduates based on the construction effect.
文摘Large open-ended pipe pile has been found to be advantageous for use in transportation projects. The current design method, however, is not adequately developed. To close this practice gap, this paper first summarized different design methods for open-ended pipe piles in sandy soils. A major factor for all the design codes is to properly account for the formation and effects of soil plug. The comparison indicates that there is a large variation in the base capacity evaluation among different methods due to the complex behaviors of soil plug. To close the knowledge gap, discrete element method （DEM） was used to simulate the soil plugging process and provide insight on the plugging mechanism. The simulation results show that the arching effect significantly increases the internal unit shear resistance along pipe piles. The porosity distribution and particle contact force distribution from DEM model indicate a large stress concentration occurs at the bottom of the soil plug. Besides, nearly 90% of the plug resistance is provided by the bottom half portion of the soil column. The soil-pile friction coefficient has a significant effect on the magnitude of plug resistance, with the major transition occurred for friction coefficient between 0.3 and 0.4.
基金Supported by the Zhejiang Province General Medical Health Research Program(No.2016KYB315)
文摘Objective: To design a new open-end intracranial hematoma drainage tube for clinical application. Methods: The newly developed device consists of two parts: the plunger and barrel.On one side, the barrel is bullet shaped with an opening tip. The plunger is located in the middle cavity of the tube barrel and extended out at the open-end. It was designed for strengthening the tube barrel and for convenience in performing the drainage procedure. It can be used by inserting the drainage tube into the lesion and pulling out the plunger, whereby blood will forcefully rise up inside the barrel, providing a satisfactory outcome. It is made for effusion drainage purposes. During the procedure, the drainage tip is placed at the deepest part of the intracranial hematoma to completely drain the blood. Moreover, the plunger fits tightly in the tube, preventing leakage during the operation. With the use of the device, brain can be separated. In addition, the device can help reduce the risk of cerebral damage because of the small operating area. The barrel sidewall has matching opening holes bilaterally and equally for exchanging substances between the inner and outer parts.The overlapping ratio in each horizontal pair is around 1/3–1/2. Each pair on the opposite side will form a different pressure. Thus, the opening holes will not easily get blocked with blood clot. Results: Blood and accumulated liquid from the deepest part of the intracranial hematoma can be directly drawn through the drainage tube without damaging a large area. The tube does not get blocked easily and allows for complete removal of the hematoma. Conclusions: The device is asuitable instrument for clinical application.
文摘In open-ended piles, inner friction is developed between inner pile shaf and the inner soil. Inner frictional resistance depends largely on the degree of soil plugging, which is influenced by many factors including pile diameter, relative density and end conditions of piles. In this paper, effects of inner sleeves on inner frictional resistance are discussed. The experiments were conducted on a medium-dense sandy ground using laboratory-scale piles. It was observed that the piles penetrated under partially-plugged or unplugged state. The results suggest that inner fiictional resistance, Qin increases with sleeve height, l linearly and requires 2D （D is pile outer diameter） of l to produce a large as 50% of Qt by Qin （Qt is total resistance）. The results also indicate that bearing capacity increases with wall thickness at the pile tip, which can be attributed to the increase in annular area. The results also indicate that soil plug height is independent of sleeve height. The results also reveal that the penetration of straight piles is closer to unplugged state than the sleeved piles. The results of incremental filling ratio and plug length ratio also indicate that the degree of soil plugging is affected by the sleeve height.
