A moving rigid-body and an unrestrained Timoshenko beam, which is subjected to the transverse impact of the rigid-body, are treated as a contact-impact system. The generalized Fourier-series method was used to derive ...A moving rigid-body and an unrestrained Timoshenko beam, which is subjected to the transverse impact of the rigid-body, are treated as a contact-impact system. The generalized Fourier-series method was used to derive the characteristic equation and the characteristic function of the system. The analytical solutions of the impact responses for the system were presented. The responses can be divided into two parts: elastic responses and rigid responses. The momentum sum of elastic responses of the contact-impact system is demonstrated to be zero, which makes the rigid responses of the system easy to evaluate according to the principle of momentum conservation.展开更多
The generalized Fourier-series method was used to derive the impact responses formula of an unrestrained planar frame structure when subjected to an impact of a moving rigid-body. By using these formula, the analytic ...The generalized Fourier-series method was used to derive the impact responses formula of an unrestrained planar frame structure when subjected to an impact of a moving rigid-body. By using these formula, the analytic solutions of dynamic responses of the contact-impact system can be obtained. During the derivation, the momentum sum of elastic responses of the contact-impact system is demonstrated to be zero. From the derivation, it is seen that the modal method can also be used to solve this kind of impact problem.展开更多
By using the formula derived in Part （ Ⅰ ）, the instant response of an unrestrained planar frame structure subjected to the impact of a moving rigid-body are evaluated and analysed. The impact force-time history be...By using the formula derived in Part （ Ⅰ ）, the instant response of an unrestrained planar frame structure subjected to the impact of a moving rigid-body are evaluated and analysed. The impact force-time history between the structure and the moving rigid-body, shear force and bending moment distribution along the beams, axial force distribution along the bars were calculated. The wave propagation phenomena of the longitudinal wave in the bars, the flexural and shear waves in the beams were also analysed. The numerical results show that the time duration of impact force is controlled by the flexural wave and the longitudinal wave ; the shear effect in beams should not be neglected in the impact response analysis of structures.展开更多
The purpose of this study was to investigate the effect of leadership on job creativity in the public institutions of the state of Kuwait. Population of the study consisted of some public bodies, namely： General Inve...The purpose of this study was to investigate the effect of leadership on job creativity in the public institutions of the state of Kuwait. Population of the study consisted of some public bodies, namely： General Investment Corporation, Kuwait Development Fund, Ministry of Planning, and Civil Service Department. There are 540 questionnaires distributed, 15 recovered, and 525 of the distributed questionnaires good for statistical analysis. Analysis of the data depended on descriptive statistical analysis, multi and simple regression. Following the hypotheses test by using the F-test, T-test, R2 coefficient and the One-Way variance analysis （ANOVA） test, the study reached the following results： There is a relation between leadership patterns and job creativity in the public institutions of the State of Kuwait. The relation is considered of medium strength, because r = 56.4% and this result matched the results of the previous studies that dealt with the same subject, which indicated that the leadership patterns affect the creative behavior in the organizations at different levels according to the prevalent pattern type. This enhances the logicality of the result, which means that the leadership patterns play a vital role in job creativity in various institutions. Results of the study showed that the democratic pattern is the most prevalent leadership pattern among managers, followed by the unrestrained pattern and finally the authoritarian pattern. Analysis results revealed that there is a weak relation between the authoritarian pattern and the job creativity in the public institutions of the State of Kuwait. The weakness of relation between the two variables can be interpreted in view of the fact that the increase of authoritarianism in leadership might give adverse results contrary to the expected and consequently, it is logical that the relation would be weak between the authoritative management approach and job creativity. There is a concern in providing work environment that encourages change in the public institutions of the State of Kuwait. Managers remarkably support the employees＇ efforts in performing the job. The study was concluded by the following recommendations： The effect of the leadership patterns on creative behavior was reached and therefore, the author recommended that it is necessary to choose well-qualified leadership that contributes to achieving excellence in the institutions operating in different sectors; to hold workshops, committees, seminars, and conferences in order to enhance confidence between management and employees; to concentrate on enhancing the democratic administrative pattern in the institutions due to its immense influence on the creative behavior of employees.展开更多
文摘A moving rigid-body and an unrestrained Timoshenko beam, which is subjected to the transverse impact of the rigid-body, are treated as a contact-impact system. The generalized Fourier-series method was used to derive the characteristic equation and the characteristic function of the system. The analytical solutions of the impact responses for the system were presented. The responses can be divided into two parts: elastic responses and rigid responses. The momentum sum of elastic responses of the contact-impact system is demonstrated to be zero, which makes the rigid responses of the system easy to evaluate according to the principle of momentum conservation.
文摘The generalized Fourier-series method was used to derive the impact responses formula of an unrestrained planar frame structure when subjected to an impact of a moving rigid-body. By using these formula, the analytic solutions of dynamic responses of the contact-impact system can be obtained. During the derivation, the momentum sum of elastic responses of the contact-impact system is demonstrated to be zero. From the derivation, it is seen that the modal method can also be used to solve this kind of impact problem.
文摘By using the formula derived in Part （ Ⅰ ）, the instant response of an unrestrained planar frame structure subjected to the impact of a moving rigid-body are evaluated and analysed. The impact force-time history between the structure and the moving rigid-body, shear force and bending moment distribution along the beams, axial force distribution along the bars were calculated. The wave propagation phenomena of the longitudinal wave in the bars, the flexural and shear waves in the beams were also analysed. The numerical results show that the time duration of impact force is controlled by the flexural wave and the longitudinal wave ; the shear effect in beams should not be neglected in the impact response analysis of structures.
文摘The purpose of this study was to investigate the effect of leadership on job creativity in the public institutions of the state of Kuwait. Population of the study consisted of some public bodies, namely： General Investment Corporation, Kuwait Development Fund, Ministry of Planning, and Civil Service Department. There are 540 questionnaires distributed, 15 recovered, and 525 of the distributed questionnaires good for statistical analysis. Analysis of the data depended on descriptive statistical analysis, multi and simple regression. Following the hypotheses test by using the F-test, T-test, R2 coefficient and the One-Way variance analysis （ANOVA） test, the study reached the following results： There is a relation between leadership patterns and job creativity in the public institutions of the State of Kuwait. The relation is considered of medium strength, because r = 56.4% and this result matched the results of the previous studies that dealt with the same subject, which indicated that the leadership patterns affect the creative behavior in the organizations at different levels according to the prevalent pattern type. This enhances the logicality of the result, which means that the leadership patterns play a vital role in job creativity in various institutions. Results of the study showed that the democratic pattern is the most prevalent leadership pattern among managers, followed by the unrestrained pattern and finally the authoritarian pattern. Analysis results revealed that there is a weak relation between the authoritarian pattern and the job creativity in the public institutions of the State of Kuwait. The weakness of relation between the two variables can be interpreted in view of the fact that the increase of authoritarianism in leadership might give adverse results contrary to the expected and consequently, it is logical that the relation would be weak between the authoritative management approach and job creativity. There is a concern in providing work environment that encourages change in the public institutions of the State of Kuwait. Managers remarkably support the employees＇ efforts in performing the job. The study was concluded by the following recommendations： The effect of the leadership patterns on creative behavior was reached and therefore, the author recommended that it is necessary to choose well-qualified leadership that contributes to achieving excellence in the institutions operating in different sectors; to hold workshops, committees, seminars, and conferences in order to enhance confidence between management and employees; to concentrate on enhancing the democratic administrative pattern in the institutions due to its immense influence on the creative behavior of employees.
