A disc-type magneto-rheological fluid damper operating in shear mode is proposed in this paper,which is based on the special characteristics of the magneto-rheological (MR) fluid with rapid, reversible and dramatic ch...A disc-type magneto-rheological fluid damper operating in shear mode is proposed in this paper,which is based on the special characteristics of the magneto-rheological (MR) fluid with rapid, reversible and dramatic change in its rheological properties by the application of an external magnetic field. The magneticfield of the disc-type MR fluid damper is analysed by the finite element method ; the controllability of the disctype MR fluid damper on the dynamic behaviour of a rotor system ; and the effectiveness of the disc-type MR fluid damper in controlling the vibration of a rotor system, are studied in a flexible rotor system with an over-hung disc. It is shown that the magnetic flux density of the disc-type MR fluid damper in the working areas can significantly change with the applied current in the coil ; and that the dynamic behavior of the disc-type MR fluid damper can be varied by the application of an external magnetic field produced by a low voltage electromagnetic coil. The disc-type MR fluid damper can significantly change the dynamic characteristics of a rotor system, provided that the location of the disk-type MR fluid damper is carefully chosen. The disc-type MR fluid damper is a new actuator with good dynamic characteristics for rotating machinery.展开更多
The paper describes information technologies （IT） role in organization---especially its influence on organizational structure. Article concerns the importance of analyzing IT acceptance, while describing IT in organ...The paper describes information technologies （IT） role in organization---especially its influence on organizational structure. Article concerns the importance of analyzing IT acceptance, while describing IT in organization and points out that inadequate variable choice may influence validity of IT analysis. First part of the article describes both variables analyzed in presented research--IT dissemination and IT acceptance. It also presents how in theory IT can influence organizational structure. The main part of the article describes empirical studies conducted in order to verify if the influence of IT on the organizational structure exists. First, the main goal and methodology of the empirical studies are presented. Variables used to assess IT and organizational structure in organizations are discussed. Then, there is a description of research results--statistical correlation between analyzed variables and regression models is shown. Conclusion of the article is that IT can influence organizational structure, but the most important factor ensuring this influence is the actual use of IT by employees of the organization--their access to IT is not enough.展开更多
Magneto-rheological (MR) fluid-based dampers are currently being explored for their potential implementation in intelligent vehicle suspension designs. Due to inherent hysteretic force properties of the MR dampers, an...Magneto-rheological (MR) fluid-based dampers are currently being explored for their potential implementation in intelligent vehicle suspension designs. Due to inherent hysteretic force properties of the MR dampers, analyzing and suppressing the MR-damper hysteresis effects, therefore, impose a great challenge. A quarter-vehicle MR-suspension model is formulated in conjunction with proposed hysteretic and mean MR-damper models, and the passive and semi-actively controlled MR-suspension systems are focused to investigate the influence of MR-damper force hysteresis. The semi-actively controlled MR-suspension employs the “on-off” control law in response to direction of the damper velocity, so as to generate the asymmetric damping force property form the symmetric MR-damper design. The results show that the MR-damping hysteresis yields serious transients and oscillations in responses for the semi-actively controlled MR-suspension than the passive MR-suspension due to the current-switching discontinuity, and would thus deteriorate the suspension performance. The undesired strong transients and oscillations in responses can be effectively suppressed by employing the proposed smooth technique without phase shift for modulating the command current discontinuity.展开更多
In many regions both urban expansion and rural development take place simultaneously, and for the purpose of understanding the dynamic process of land use/cover change （LUCC） in such large areas, this study develops...In many regions both urban expansion and rural development take place simultaneously, and for the purpose of understanding the dynamic process of land use/cover change （LUCC） in such large areas, this study develops a multi-agent based land use model. Taking the Poyang Lake area of China as a typical case, this study applies the mechanism of diffusion-limited aggregation to simulate the behavior of urban agents, while rural land use is illustrated with a bottom-up based model consisting of agent and environment layers. In the agent layer, each household agent makes its own decisions on land use, and at each time interval a government agent takes control of land use by implementing policies. According to incomes and the rate of migrant workers, household agents are divided into six categories, among which different decision rules are followed. For complex LUCC in the Poyang Lake area of China from 1985 to 2005, the artificial society model developed in this study yields results highly consistent with observations. Importantly, it is shown that governmental policies can impose significant effects on the decisions of individual household agents on land use and the multi-agent-based land use model developed in this study provides a robust means for assessing the effectiveness of governmental policies.展开更多
The concept of global governance first appeared in research on international political governance in the early 1990s. At the time much of the theoretical research on global governance was to some extent isolated from ...The concept of global governance first appeared in research on international political governance in the early 1990s. At the time much of the theoretical research on global governance was to some extent isolated from the realities of world development, but since the beginning of the 21th century, global governance research has been turning to real world issues, We propose the construction, from a public management perspective, of a governance ＂issue-actor-mechanism＂ framework. This sees postwar global governance practice as the old paradigm. The paper points out that the rapid global development after the end of the Cold War has had a crucial impact on the traditional governance paradigm, followed by the emergence of new global governance issues and changes in new governance actors resulting from the changing world of the last twenty or thirty years which have led to the failure of traditional governance mechanisms. These ＂issue-actor-mechanism＂ changes are closely interlocked, and hence require a new global governance paradigm that can reflect the complex interconnections of governance issues, actors and mechanisms. We thus need to reexamine and refresh our perceptions of the world and open up a new research agenda.展开更多
The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112 and slip on {111} 110 systems. The influence of ξ ...The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112 and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.展开更多
文摘A disc-type magneto-rheological fluid damper operating in shear mode is proposed in this paper,which is based on the special characteristics of the magneto-rheological (MR) fluid with rapid, reversible and dramatic change in its rheological properties by the application of an external magnetic field. The magneticfield of the disc-type MR fluid damper is analysed by the finite element method ; the controllability of the disctype MR fluid damper on the dynamic behaviour of a rotor system ; and the effectiveness of the disc-type MR fluid damper in controlling the vibration of a rotor system, are studied in a flexible rotor system with an over-hung disc. It is shown that the magnetic flux density of the disc-type MR fluid damper in the working areas can significantly change with the applied current in the coil ; and that the dynamic behavior of the disc-type MR fluid damper can be varied by the application of an external magnetic field produced by a low voltage electromagnetic coil. The disc-type MR fluid damper can significantly change the dynamic characteristics of a rotor system, provided that the location of the disk-type MR fluid damper is carefully chosen. The disc-type MR fluid damper is a new actuator with good dynamic characteristics for rotating machinery.
文摘The paper describes information technologies （IT） role in organization---especially its influence on organizational structure. Article concerns the importance of analyzing IT acceptance, while describing IT in organization and points out that inadequate variable choice may influence validity of IT analysis. First part of the article describes both variables analyzed in presented research--IT dissemination and IT acceptance. It also presents how in theory IT can influence organizational structure. The main part of the article describes empirical studies conducted in order to verify if the influence of IT on the organizational structure exists. First, the main goal and methodology of the empirical studies are presented. Variables used to assess IT and organizational structure in organizations are discussed. Then, there is a description of research results--statistical correlation between analyzed variables and regression models is shown. Conclusion of the article is that IT can influence organizational structure, but the most important factor ensuring this influence is the actual use of IT by employees of the organization--their access to IT is not enough.
文摘Magneto-rheological (MR) fluid-based dampers are currently being explored for their potential implementation in intelligent vehicle suspension designs. Due to inherent hysteretic force properties of the MR dampers, analyzing and suppressing the MR-damper hysteresis effects, therefore, impose a great challenge. A quarter-vehicle MR-suspension model is formulated in conjunction with proposed hysteretic and mean MR-damper models, and the passive and semi-actively controlled MR-suspension systems are focused to investigate the influence of MR-damper force hysteresis. The semi-actively controlled MR-suspension employs the “on-off” control law in response to direction of the damper velocity, so as to generate the asymmetric damping force property form the symmetric MR-damper design. The results show that the MR-damping hysteresis yields serious transients and oscillations in responses for the semi-actively controlled MR-suspension than the passive MR-suspension due to the current-switching discontinuity, and would thus deteriorate the suspension performance. The undesired strong transients and oscillations in responses can be effectively suppressed by employing the proposed smooth technique without phase shift for modulating the command current discontinuity.
基金Chinese R&D Program of "Development of a comprehensive monitoring and evaluation system for ecological compensation of typical ecologically vulnerable regions of China (2006BAC08B06)"National Science Fund for Distinguished Young Scholars (40788001)One Hundred Talents Program of the Chinese Academy of Sciences
文摘In many regions both urban expansion and rural development take place simultaneously, and for the purpose of understanding the dynamic process of land use/cover change （LUCC） in such large areas, this study develops a multi-agent based land use model. Taking the Poyang Lake area of China as a typical case, this study applies the mechanism of diffusion-limited aggregation to simulate the behavior of urban agents, while rural land use is illustrated with a bottom-up based model consisting of agent and environment layers. In the agent layer, each household agent makes its own decisions on land use, and at each time interval a government agent takes control of land use by implementing policies. According to incomes and the rate of migrant workers, household agents are divided into six categories, among which different decision rules are followed. For complex LUCC in the Poyang Lake area of China from 1985 to 2005, the artificial society model developed in this study yields results highly consistent with observations. Importantly, it is shown that governmental policies can impose significant effects on the decisions of individual household agents on land use and the multi-agent-based land use model developed in this study provides a robust means for assessing the effectiveness of governmental policies.
文摘The concept of global governance first appeared in research on international political governance in the early 1990s. At the time much of the theoretical research on global governance was to some extent isolated from the realities of world development, but since the beginning of the 21th century, global governance research has been turning to real world issues, We propose the construction, from a public management perspective, of a governance ＂issue-actor-mechanism＂ framework. This sees postwar global governance practice as the old paradigm. The paper points out that the rapid global development after the end of the Cold War has had a crucial impact on the traditional governance paradigm, followed by the emergence of new global governance issues and changes in new governance actors resulting from the changing world of the last twenty or thirty years which have led to the failure of traditional governance mechanisms. These ＂issue-actor-mechanism＂ changes are closely interlocked, and hence require a new global governance paradigm that can reflect the complex interconnections of governance issues, actors and mechanisms. We thus need to reexamine and refresh our perceptions of the world and open up a new research agenda.
基金supported by the National Natural Science Foundation of China(Grant Nos.50301016 and 59971067)the China Postdoctoral Science Foundation(Grant No.2005037003).
文摘The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112 and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.
