The effects of the interactions between bi-directional pedestrians on the crossing time and the crosswalk width are studied. Firstly,the crossing process of bi-directional pedestrians is analyzed.The total crosswalk t...The effects of the interactions between bi-directional pedestrians on the crossing time and the crosswalk width are studied. Firstly,the crossing process of bi-directional pedestrians is analyzed.The total crosswalk time is divided into a discharge time and a crossing time. The interactions between bi-directional pedestrians are quantified with the drag force theory. Then,a model is developed to study the crossing time based on the kinetic energy theory and momentum theory. Subsequently,the related parameters of the proposed model are calibrated with observed information. The relationships among crosswalk width,signal time,pedestrian volume and level of service are simulated with the proposed model. The results are verified and compared with other models. The proposed model has an absolute value of relative error of 9. 38%,which is smaller than that of the Alhajyaseen model（ 15. 26%） and Highway Capacity Manual（ HCM） model（ 12. 42%）. Finally,suggested crosswalk widths at different conditions are successfully estimated with the proposed crossing time model.展开更多
烟丝的宽度是衡量卷烟质量的重要指标,为了能够实时把控烟丝质量,该文设计一种烟丝宽度实时在线检测方法。该文将YOLOv4中的SPP和PANet结构进行融合,并将输出三种输出尺度改为一种输出尺度,使改进后的YOLOv4算法结构更加简单,在性能几...烟丝的宽度是衡量卷烟质量的重要指标,为了能够实时把控烟丝质量,该文设计一种烟丝宽度实时在线检测方法。该文将YOLOv4中的SPP和PANet结构进行融合,并将输出三种输出尺度改为一种输出尺度,使改进后的YOLOv4算法结构更加简单,在性能几乎不下降的情况下,运算速度提升近35%;烟丝宽度计算方法是该文设计的MCS(Moving Center Search)中心移动搜索法。该方法能够自动搜索出烟丝的两个侧边,并较为精确地计算出烟丝宽度,计算精度可达0.2毫米。将MCS烟丝宽度计算方法与该文改进后的YOLOv4模型相结合,能够进行实时在线的烟丝宽度检测,实时把控烟丝生产质量,提升生产效率。展开更多
A study of the evolution of the pulse width in homogeneous dielectric barrier dis- charge at atmospheric pressure with helium as the working gas is reported by using a one- dimensional fluid model. In this paper, a ne...A study of the evolution of the pulse width in homogeneous dielectric barrier dis- charge at atmospheric pressure with helium as the working gas is reported by using a one- dimensional fluid model. In this paper, a new computational method is presented to estimate the pulse width through calculating the time interval between the breakdown voltage and the extinguishing voltage. The effects on the discharge characteristics of the applied voltage and exci- tation frequency are studied based on the computational data. The results of the simulation show that the pulse width is observed to be narrower and the time intervals between two consecutive current pulses decrease with increasing amplitude and excitation frequency, which indicates that the homogeneous discharge is susceptible to the filamentary mode. The simulation results support the conclusion that in order to restrain the transition from the glow mode to filamentary mode, the applied voltage and excitation frequency should be kept within an appropriate range.展开更多
Using the method of Laplace transform, analytical expressions are derived for the time periodic pulse electroosmotic flow (EOF) velocity of the triangle and sawtooth of Maxwell fluid in circular microchannel. The solu...Using the method of Laplace transform, analytical expressions are derived for the time periodic pulse electroosmotic flow (EOF) velocity of the triangle and sawtooth of Maxwell fluid in circular microchannel. The solution involves analytically solving the linearized Poisson-Boltzmann (P-B) equation, together with the Cauchy momentum equation and the general Maxwell constitutive equation. By numerical computations of inverse Laplace transform, the effects of electrokinetic width <em>K</em>, relaxation time <img src="Edit_ac271231-18df-479a-bb85-bcac486dfbb1.bmp" alt="" /> and pulse width <em>a</em> on the above several pulse EOF velocities are investigated. In addition, we focused on the comparison and analysis of the formulas and graphs between the triangle and sawtooth pulse EOF with the rectangle pulse EOF. The study found that there are obvious differences in formulas and graphs between triangle and sawtooth pulse EOF with rectangle pulse EOF, and the difference mainly depends on the different definitions of the three kinds of time periodic pulse waves. Finally, we also studied the stability of the above three kinds of pulse EOF and the influence of relaxation time on pulse EOF velocity under different pulse widths is discussed. We find that the rectangle pulse EOF is more stable than the triangle and sawtooth pulse EOF. For any pulse, as the pulse width <em>a</em> increases, the influence of the relaxation time on the pulse EOF velocity will be weakened.展开更多
基金Supported by the National Natural Science Foundation of China(51278220)
文摘The effects of the interactions between bi-directional pedestrians on the crossing time and the crosswalk width are studied. Firstly,the crossing process of bi-directional pedestrians is analyzed.The total crosswalk time is divided into a discharge time and a crossing time. The interactions between bi-directional pedestrians are quantified with the drag force theory. Then,a model is developed to study the crossing time based on the kinetic energy theory and momentum theory. Subsequently,the related parameters of the proposed model are calibrated with observed information. The relationships among crosswalk width,signal time,pedestrian volume and level of service are simulated with the proposed model. The results are verified and compared with other models. The proposed model has an absolute value of relative error of 9. 38%,which is smaller than that of the Alhajyaseen model（ 15. 26%） and Highway Capacity Manual（ HCM） model（ 12. 42%）. Finally,suggested crosswalk widths at different conditions are successfully estimated with the proposed crossing time model.
文摘烟丝的宽度是衡量卷烟质量的重要指标,为了能够实时把控烟丝质量,该文设计一种烟丝宽度实时在线检测方法。该文将YOLOv4中的SPP和PANet结构进行融合,并将输出三种输出尺度改为一种输出尺度,使改进后的YOLOv4算法结构更加简单,在性能几乎不下降的情况下,运算速度提升近35%;烟丝宽度计算方法是该文设计的MCS(Moving Center Search)中心移动搜索法。该方法能够自动搜索出烟丝的两个侧边,并较为精确地计算出烟丝宽度,计算精度可达0.2毫米。将MCS烟丝宽度计算方法与该文改进后的YOLOv4模型相结合,能够进行实时在线的烟丝宽度检测,实时把控烟丝生产质量,提升生产效率。
基金supported by National Natural Science Foundation of China(No.51077089)
文摘A study of the evolution of the pulse width in homogeneous dielectric barrier dis- charge at atmospheric pressure with helium as the working gas is reported by using a one- dimensional fluid model. In this paper, a new computational method is presented to estimate the pulse width through calculating the time interval between the breakdown voltage and the extinguishing voltage. The effects on the discharge characteristics of the applied voltage and exci- tation frequency are studied based on the computational data. The results of the simulation show that the pulse width is observed to be narrower and the time intervals between two consecutive current pulses decrease with increasing amplitude and excitation frequency, which indicates that the homogeneous discharge is susceptible to the filamentary mode. The simulation results support the conclusion that in order to restrain the transition from the glow mode to filamentary mode, the applied voltage and excitation frequency should be kept within an appropriate range.
文摘Using the method of Laplace transform, analytical expressions are derived for the time periodic pulse electroosmotic flow (EOF) velocity of the triangle and sawtooth of Maxwell fluid in circular microchannel. The solution involves analytically solving the linearized Poisson-Boltzmann (P-B) equation, together with the Cauchy momentum equation and the general Maxwell constitutive equation. By numerical computations of inverse Laplace transform, the effects of electrokinetic width <em>K</em>, relaxation time <img src="Edit_ac271231-18df-479a-bb85-bcac486dfbb1.bmp" alt="" /> and pulse width <em>a</em> on the above several pulse EOF velocities are investigated. In addition, we focused on the comparison and analysis of the formulas and graphs between the triangle and sawtooth pulse EOF with the rectangle pulse EOF. The study found that there are obvious differences in formulas and graphs between triangle and sawtooth pulse EOF with rectangle pulse EOF, and the difference mainly depends on the different definitions of the three kinds of time periodic pulse waves. Finally, we also studied the stability of the above three kinds of pulse EOF and the influence of relaxation time on pulse EOF velocity under different pulse widths is discussed. We find that the rectangle pulse EOF is more stable than the triangle and sawtooth pulse EOF. For any pulse, as the pulse width <em>a</em> increases, the influence of the relaxation time on the pulse EOF velocity will be weakened.
