Time filter

Source Type

Shenzhen, China

Shenzhen University is a public university established in 1983 located in Shenzhen, Guangdong, China. It is accredited by the State Council of the People's Republic of China and is funded by the Shenzhen government. The university took its first enrollment the same year at what Deng Xiaoping called "Shenzhen Speed". Wikipedia.

Zhang K.,Shenzhen University | Wang S.,University of Western Australia
Automatica | Year: 2012

We develop a novel numerical method to price American options on a discount bond under the CoxIngrosllRoss (CIR) model which is governed by a partial differential complementarity problem. We first propose a penalty approach to this complementarity problem, resulting in a nonlinear partial differential equation (PDE). To numerically solve this nonlinear PDE, we develop a novel fitted finite volume method for the spatial discretization, coupled with a fully implicit time-stepping scheme. We show that this full discretization scheme is consistent, stable and monotone, and hence the convergence of the numerical solution to the viscosity solution of the continuous problem is guaranteed. To solve the discretized nonlinear system, we design an iterative method and prove that the method is convergent. Numerical results are presented to demonstrate the accuracy, efficiency and robustness of our methods. © 2012 Elsevier Ltd. All rights reserved.

Tao S.,Central South University | Yu W.,Shenzhen University
Optics Express | Year: 2015

We present a beam shaping technique in controlling the complex amplitude of an optical beam. The constraint on the amplitude of the output beam in the Gerchberg-Saxton algorithm is replaced with constraints both on the amplitude and phase of the output beam in the proposed method. The total areas of the constrained regions and free regions on the complex amplitude of the output beam in the proposed method are maintained. An output beam with arbitrary complex amplitude can be realized with the proposed method. The computing result from the proposed method is a phase-only distribution, which can be fabricated as diffractive optical element for higher diffraction efficiency. Both simulations and experiments are present and the effectiveness of the proposed method is verified. ©2015 Optical Society of America.

Liu Z.X.,Shenzhen University
Science China Information Sciences | Year: 2013

The probability hypothesis density (PHD) filter provides an efficiently parallel processing method for multi-target tracking. However, measurements have to be gathered for a scan period before the PHD filter can perform a recursion, therefore, significant delay may arise if the scan period is long. To reduce the delay in the PHD filter, we propose a sequential PHD filter which updates the posterior intensity whenever a new measurement becomes available. An implementation of the sequential PHD filter for a linear Gaussian system is also developed. The unique characteristic of the proposed filter is that it can retain the useful information of missed targets in the posterior intensity and sequentially handle the received measurements in time. © 2013 Science China Press and Springer-Verlag Berlin Heidelberg.

Qu X.,Shenzhen University
Journal of NeuroEngineering and Rehabilitation | Year: 2014

Background: Though it is well recognized that gait characteristics are affected by concurrent cognitive tasks, how different working memory components contribute to dual task effects on gait is still unknown. The objective of the present study was to investigate dual-task effects on gait characteristics, specifically the application of cognitive tasks involving different working memory components. In addition, we also examined age-related differences in such dual-task effects. Methods: Three cognitive tasks (i.e. 'Random Digit Generation', 'Brooks' Spatial Memory', and 'Counting Backward') involving different working memory components were examined. Twelve young (6 males and 6 females, 20 ~ 25 years old) and 12 older participants (6 males and 6 females, 60 ~ 72 years old) took part in two phases of experiments. In the first phase, each cognitive task was defined at three difficulty levels, and perceived difficulty was compared across tasks. The cognitive tasks perceived to be equally difficult were selected for the second phase. In the second phase, four testing conditions were defined, corresponding to a baseline and the three equally difficult cognitive tasks. Participants walked on a treadmill at their self-selected comfortable speed in each testing condition. Body kinematics were collected during treadmill walking, and gait characteristics were assessed using spatial-temporal gait parameters. Results: Application of the concurrent Brooks' Spatial Memory task led to longer step times compared to the baseline condition. Larger step width variability was observed in both the Brooks' Spatial Memory and Counting Backward dual-task conditions than in the baseline condition. In addition, cognitive task effects on step width variability differed between two age groups. In particular, the Brooks' Spatial Memory task led to significantly larger step width variability only among older adults. Conclusion: These findings revealed that cognitive tasks involving the visuo-spatial sketchpad interfered with gait more severely in older versus young adults. Thus, dual-task training, in which a cognitive task involving the visuo-spatial sketchpad (e.g. the Brooks' Spatial Memory task) is concurrently performed with walking, could be beneficial to mitigate impairments in gait among older adults. © 2014 Qu; licensee BioMed Central Ltd.

Shenzhen University | Date: 2015-04-17

A mechanically rotating intravascular ultrasound probe relates to the technical field of medical devices, and aims to provide a forward-looking mechanically rotating intravascular ultrasound probe having a small volume, a high image resolution and good imaging stability. The intravascular ultrasound probe includes a catheter, an ultrasonic transducer disposed at a front end of a cavity of the catheter and a driving apparatus that drives the ultrasonic transducer to rotate mechanically. The driving apparatus is a micro motor disposed in the cavity of the catheter, including a rotor and a stator. The ultrasonic transducer is installed on top of the rotor and electrically connected to the rotor, and the rotor is also electrically connected to the stator; the catheter is a magnetic metal tube, and a front end thereof is enclosed by an acoustic window which has a spherical tip and allows ultrasonic waves of the ultrasonic transducer to pass through; the acoustic window is filled with an ionic liquid having a function of a ultrasonic coupling agent. The ultrasound probe solves a problem of rotation torsion of an image when the catheter passes through a lesion with high-grade stenosis or a curved blood vessel section, and achieves forward scanning imaging and side scanning imaging for a blood vessel wall.

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