In this study,we focused on a novel parallel mechanism for utilizing the motion simulator of a high-speed boat(HSB).First,we expressed the real behavior of the HSB based on a seakeeping trial.For this purpose,we recor...In this study,we focused on a novel parallel mechanism for utilizing the motion simulator of a high-speed boat(HSB).First,we expressed the real behavior of the HSB based on a seakeeping trial.For this purpose,we recorded the motion parameters of the HSB by gyroscope and accelerometer sensors,while using a special data acquisition technique.Additionally,a Chebychev highpass filter was applied as a noise filter to the accelerometer sensor.Then,a novel 3 degrees of freedom(DoF)parallel mechanism(1T2R)with prismatic actuators is proposed and analyses were performed on its inverse kinematics,velocity,and acceleration.Finally,the inverse dynamic analysis is presented by the principle of virtual work,and the validation of the analytical equations was compared by the ADAMS simulation software package.Additionally,according to the recorded experimental data of the HSB,the feasibility of the proposed novel parallel mechanism motion simulator of the HSB,as well as the necessity of using of the washout filters,was explored.展开更多
When an electromagnetic signal transmits through a coaxial cable, it propagates at speed determined by the dielectrics of insulator between the cooper core wire and the metallic shield. However, we demonstrate here th...When an electromagnetic signal transmits through a coaxial cable, it propagates at speed determined by the dielectrics of insulator between the cooper core wire and the metallic shield. However, we demonstrate here that, once the shielding layer of the coaxial cable is cut into two parts leaving a small gap, while the copper core wire is still perfectly connected, a remarkable transmission delay immediately appears in the system. We have revealed by both computational simulation and experiments that, when the gap spacing between two parts of the shielding layer is small, this delay is mostly determined by the overall geometrical parameters of the conductive boundary which connects two parts of the cut shielding layer. A reduced analytic formula for the transmission delay related with geometrical parameters, which is based on an inductive model of the transmission system, matches well with the fitted formula of the simulated delay. This above structure is analog to the situation that an interconnect is between two inter-modules in a circuit. The results suggest that for high speed circuits and systems, parasitic inductance should be taken into full consideration, and compact conductive packaging is favorable for reducing transmission delay of inter-modules, therefore enhancing the performance of the system.展开更多
以整体优化抬落道量最小为目标进行纵断面重构时,由于纵断面整体优化中各线元数学模型不同,拟合后的线元连接处会存在错位现象,不满足相邻线元首尾相接的平顺性条件。因此,本文提出了利用引入相切条件的方向加速(Powell with Tangent Co...以整体优化抬落道量最小为目标进行纵断面重构时,由于纵断面整体优化中各线元数学模型不同,拟合后的线元连接处会存在错位现象,不满足相邻线元首尾相接的平顺性条件。因此,本文提出了利用引入相切条件的方向加速(Powell with Tangent Condition,PTC)法来重构纵断面线形。首先利用方向加速(Powell)法进行各线元拟合优化,然后对竖曲线圆心坐标进行调整,通过调整后的圆心坐标重新计算纵断面竖曲线半径及直圆点和圆直点坐标,使竖曲线与左右两侧相邻直线坡段相切。对比利用PTC法与传统的曲率分段结合最小二乘法重构线形的抬落道量,结果表明,PTC法对线路重构的扰动更小,优化效果更好,在减小抬落道方面有显著优势。通过动力学仿真对比Powell法和PTC法优化线形后的车体动力学指标,结果表明,PTC法重构纵断面所得的线元连接处平顺性显著提高,各车体动力学性能指标明显减小,车辆运行的安全性和舒适性得到明显改善。展开更多
文摘In this study,we focused on a novel parallel mechanism for utilizing the motion simulator of a high-speed boat(HSB).First,we expressed the real behavior of the HSB based on a seakeeping trial.For this purpose,we recorded the motion parameters of the HSB by gyroscope and accelerometer sensors,while using a special data acquisition technique.Additionally,a Chebychev highpass filter was applied as a noise filter to the accelerometer sensor.Then,a novel 3 degrees of freedom(DoF)parallel mechanism(1T2R)with prismatic actuators is proposed and analyses were performed on its inverse kinematics,velocity,and acceleration.Finally,the inverse dynamic analysis is presented by the principle of virtual work,and the validation of the analytical equations was compared by the ADAMS simulation software package.Additionally,according to the recorded experimental data of the HSB,the feasibility of the proposed novel parallel mechanism motion simulator of the HSB,as well as the necessity of using of the washout filters,was explored.
文摘When an electromagnetic signal transmits through a coaxial cable, it propagates at speed determined by the dielectrics of insulator between the cooper core wire and the metallic shield. However, we demonstrate here that, once the shielding layer of the coaxial cable is cut into two parts leaving a small gap, while the copper core wire is still perfectly connected, a remarkable transmission delay immediately appears in the system. We have revealed by both computational simulation and experiments that, when the gap spacing between two parts of the shielding layer is small, this delay is mostly determined by the overall geometrical parameters of the conductive boundary which connects two parts of the cut shielding layer. A reduced analytic formula for the transmission delay related with geometrical parameters, which is based on an inductive model of the transmission system, matches well with the fitted formula of the simulated delay. This above structure is analog to the situation that an interconnect is between two inter-modules in a circuit. The results suggest that for high speed circuits and systems, parasitic inductance should be taken into full consideration, and compact conductive packaging is favorable for reducing transmission delay of inter-modules, therefore enhancing the performance of the system.
文摘以整体优化抬落道量最小为目标进行纵断面重构时,由于纵断面整体优化中各线元数学模型不同,拟合后的线元连接处会存在错位现象,不满足相邻线元首尾相接的平顺性条件。因此,本文提出了利用引入相切条件的方向加速(Powell with Tangent Condition,PTC)法来重构纵断面线形。首先利用方向加速(Powell)法进行各线元拟合优化,然后对竖曲线圆心坐标进行调整,通过调整后的圆心坐标重新计算纵断面竖曲线半径及直圆点和圆直点坐标,使竖曲线与左右两侧相邻直线坡段相切。对比利用PTC法与传统的曲率分段结合最小二乘法重构线形的抬落道量,结果表明,PTC法对线路重构的扰动更小,优化效果更好,在减小抬落道方面有显著优势。通过动力学仿真对比Powell法和PTC法优化线形后的车体动力学指标,结果表明,PTC法重构纵断面所得的线元连接处平顺性显著提高,各车体动力学性能指标明显减小,车辆运行的安全性和舒适性得到明显改善。
