High-speed analog simulation of CMOS vision chips using explicit integration techniques on many-core processors

2012 ◽

Vol 7 (4) ◽

Cited By ~ 6

Author(s):

Liang Ling ◽

Xinbiao Xiao ◽

Xuesong Jin

Keyword(s):

High Speed ◽

Dynamical Behavior ◽

Vehicle Speed ◽

Vertical Force ◽

Explicit Integration ◽

Running Safety ◽

Earthquake Motion ◽

High Speed Trains ◽

Wheel Loading ◽

Safety Operation

In order to investigate the derailment mechanism and safety operation area of high-speed trains under earthquake, a coupled vehicle-track dynamic model considering earthquake effect is developed, in which the vehicle is modeled as a 35 degrees of freedom (DOF) multibody system with nonlinear suspension characteristic and the slab track is modeled as a discrete elastic support model. The rails of the track are assumed to be Timoshenko beams supported by discrete rail fasteners, and the slabs are modeled with solid finite elements. The system motion equations are solved by means of an explicit integration method in time domain. The present work analyzes in detail the effect of earthquake characteristics on the dynamical behaviors of a vehicle-track coupling system and the transient derailment criteria. The considered derailment criteria include the ratio of the wheel/rail lateral force to the vertical force, the wheel loading reduction, the wheel/rail contact point traces on the wheel tread, and the wheel rise with respect to the rail top, respectively. The present work also finds the safety operation area, the derailment area, and the warning area of high-speed trains under earthquake, and their boundaries. These areas consist of three key parameters influencing the dynamical behavior of high-speed train and track under earthquake. The three key influencing parameters are, respectively, the vehicle speed and the lateral and vertical peak ground acceleration (PGA) of an earthquake. The results obtained indicate that the lateral earthquake motion has a greater influence on the vehicle dynamic behavior and its running safety compared to the vertical earthquake motion. The risk of derailment increases quickly with the increasing of lateral earthquake motion amplitude. The lateral earthquake motion is dominant in the vehicle running safety influenced by an earthquake. While the vertical earthquake motion promotes jumping of the wheels easily, not easy is flange climb derailment. And the effect of the vehicle speed is not significant under earthquake.

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Receiver Integration with Arrayed Waveguide Gratings toward Multi-Wavelength Data-Centric Communications and Computing

Applied Sciences ◽

10.3390/app10228205 ◽

2020 ◽

Vol 10 (22) ◽

pp. 8205

Author(s):

Yoshiyuki Doi ◽

Toshihide Yoshimatsu ◽

Yasuhiko Nakanishi ◽

Satoshi Tsunashima ◽

Masahiro Nada ◽

...

Keyword(s):

Wavelength Division Multiplexing ◽

High Speed ◽

Baud Rate ◽

Arrayed Waveguide Gratings ◽

Wavelength Division ◽

Integrated Devices ◽

Multi Wavelength ◽

Integration Techniques ◽

Waveguide Gratings ◽

Arrayed Waveguide

This paper reviews receivers that feature low-loss multimode-output arrayed waveguide gratings (MM-AWGs) for wavelength division multiplexing (WDM) as well as hybrid integration techniques with high-speed throughput of up to 100 Gb/s and beyond. A design of optical coupling between higher-order multimode beams and a photodiode for a flat-top spectral shape is described in detail. The WDM photoreceivers were fabricated with different approaches. A 10-Gb/s photoreceiver was developed for a 1.25-Gb/s baud rate and assembled for eight-channel WDM by mechanical alignment. A receiver with 40-Gb/s throughput was built by using visual alignment for a 10-Gb/s baud rate and four-channel WDM. A 100-Gb/s receiver assembled by active alignment with a four-channel by 25-Gb/s baud rate is the basis for beyond-100 Gb/s and future multi-wavelength integrated devices toward data-centric communications and computing.

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Analysis on Impact Loading at Rail Welds at High Speed

Volume 2: Automotive Systems; Bioengineering and Biomedical Technology; Computational Mechanics; Controls; Dynamical Systems ◽

10.1115/esda2008-59383 ◽

2008 ◽

Cited By ~ 1

Author(s):

Guangwen Xiao ◽

Xinbiao Xiao ◽

Zefeng Wen ◽

Xuesong Jin

Keyword(s):

Impact Loading ◽

High Speed ◽

Hertzian Contact ◽

Railway Vehicle ◽

Vehicle Speed ◽

Explicit Integration ◽

Normal Forces ◽

Rail Irregularity ◽

Multi Body ◽

The Impact

When a railway vehicle passes through a track with different weld irregularities at high speed, the impact loading of the vehicle coupled with the track is investigated in detail using a coupled vehicle/track model. In this model, a half vehicle is considered and modeled as a multi-body system. In the track model, a Timoshenko beam resting on discrete sleepers is applied to model each rail. Each sleeper is modeled as a rigid body accounting for its vertical, lateral, roll motions. A moving sleeper support model is used to simulate the interaction of the vehicle and the track. The ballast bed is replaced with equivalent masses. The equivalent dampers and springs are used to replace the connections between the parts of the vehicle and track. In calculating the coupled vehicle and track dynamics, Hertzian contact theory and the creep force theory by Shen et al. are, respectively, used to calculate the normal forces and the creep forces between the wheels and the rails. The motion equations of the vehicle-track are solved by means of an explicit integration method. The weld rail irregularity is modeled by setting a local track vertical deviation at a rail weld joint, which is described with a simplified cosine function. In the numerical analysis the effect of the different wavelength, depth, the position of the welded joint in a sleeper span, and vehicle speed is taken into account. The numerical results obtained are greatly useful in the tolerance design of welded rail profile irregularity caused by damage and hand-grinding after rail welding.

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