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214 results on '"Liao, Shasha"'

1. On the stability and instability of Kelvin-Stuart cat's eyes flows

Author

Liao, Shasha, Lin, Zhiwu, and Zhu, Hao

Subjects
Mathematics - Analysis of PDEs
Abstract

Kelvin-Stuart vortices are classical mixing layer flows with many applications in fluid mechanics, plasma physics and astrophysics. We prove that the whole family of Kelvin-Stuart vortices is nonlinearly stable for co-periodic perturbations, and linearly unstable for multi-periodic or modulational perturbations. This verifies a long-standing conjecture since the discovery of the Kelvin-Stuart cat's eyes flows in the 1960s. Kelvin-Stuart cat's eyes also appear as magnetic islands which are magnetostatic equilibria for the 2D ideal MHD equations in plasmas. We prove nonlinear stability of Kelvin-Stuart magnetic islands for co-periodic perturbations, and give the first rigorous proof of the coalescence instability, which is important for magnetic reconnection., Comment: 124 pages. We added a comment on the stability/instability of Taylor's 2-parameter family of cat's eyes solutions, and added Lemma 3.7

Published
2023

5. Nonlinear Modulational Instability of Dispersive PDE Models

Author

Jin, Jiayin, Liao, Shasha, and Lin, Zhiwu

Subjects
Mathematics - Analysis of PDEs
Abstract

We prove nonlinear modulational instability for both periodic and localized perturbations of periodic traveling waves for several dispersive PDEs, including the KDV type equations (e.g. the Whitham equation, the generalized KDV equation, the Benjamin-Ono equation), the nonlinear Schr\"odinger equation and the BBM equation. First, the semigroup estimates required for the nonlinear proof are obtained by using the Hamiltonian structures of the linearized PDEs; Second, for KDV type equations the loss of derivative in the nonlinear term is overcome in two complementary cases: (1) for smooth nonlinear terms and general dispersive operators, we construct higher order approximation solutions and then use energy type estimates; (2) for nonlinear terms of low regularity, with some additional assumption on the dispersive operator, we use a bootstrap argument to overcome the loss of derivative.

Published
2017
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11. Experimental observation of optical differentiation and optical Hilbert transformation using a single SOI microdisk chip

Author

Yang, Ting, Dong, Jianji, Liu, Li, Liao, Shasha, Tan, Sisi, Shi, Lei, Gao, Dingshan, and Zhang, Xinliang

Subjects
Physics - Optics
Abstract

Optical differentiation and optical Hilbert transformation play important roles in communications, computing, information processing and signal analysis in optical domain which offering huge bandwidth. Meanwhile, silicon-based photonic integrated circuits are preferable in all-optical signal processing due to their intrinsic advantages of low power consumption, compact footprint and ultra-high speed. In this study, we analyze the interrelation between first-order optical differentiation and optical Hilbert transformation and then experimentally demonstrate a feasible integrated scheme which can simultaneously function as first-order optical differentiation and optical Hilbert transformation based on a single microdisk resonator. This finding may motivate the development of integrated optical signal processors., Comment: 15 pages, 6 figures

Published
2013

12. Does the Quality of Digital Teaching Materials Matter? : A Comparative Study of Art Students’ Classroom Behavior and Learning Outcomes

Author

Liu, Zhejun, Jin, Yunshui, Liao, Shasha, Zhao, Zheng, Hutchison, David, Series Editor, Kanade, Takeo, Series Editor, Kittler, Josef, Series Editor, Kleinberg, Jon M., Series Editor, Mattern, Friedemann, Series Editor, Mitchell, John C., Series Editor, Naor, Moni, Series Editor, Pandu Rangan, C., Series Editor, Steffen, Bernhard, Series Editor, Terzopoulos, Demetri, Series Editor, Tygar, Doug, Series Editor, Weikum, Gerhard, Series Editor, Zaphiris, Panayiotis, editor, and Ioannou, Andri, editor

Published
2018
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14. Workload-Aware VM Consolidation in Cloud Based on Max-Min Ant System

Author

Zhang, Hongjie, Shu, Guansheng, Liao, Shasha, Fu, Xi, Li, Jing, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, Sun, Xingming, editor, Chao, Han-Chieh, editor, You, Xingang, editor, and Bertino, Elisa, editor

Published
2017
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16. Si3N4-Based Narrowband and High Peak Rejection Microwave Photonic Filter With Adjustable Bandwidth

Author

Liu, Li and Liao, Shasha

Abstract

A narrowband notch microwave photonic filter (MPF) with adjustable bandwidth and ultra-high rejection ratio is proposed and experimentally demonstrated leveraging a Mach–Zehnder interferometer (MZI) coupled Si3N4 ring resonator. The ring is designed with two interferometric coupling waveguides so as to tune the effective coupling coefficients between the bending waveguides and the resonator. Consequently, the bandwidth and the extinction ratio of the resonator could be adjusted. Leveraging the MZI-coupled Si3N4 ring, the experimental results illustrate that the 3dB-bandwidth of the notch microwave filters can be effectively adjusted. Furthermore, during the bandwidth tuning process, the rejection ratios of the notch MPFs could obtain high values by utilizing the interference cancellation. To our knowledge, with maintaining ultra-high rejections beyond 60 dB, the 3dB-bandwidth of the Si3N4-based notch MPFs is firstly verified with an adjustable range from tens of MHz to GHz level. The proposed narrowband MPF schemes with superior bandwidth tunability and ultra-high rejection ratios have various important applications in integrated radio frequency systems.

Published
2024
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17. DRL-enabled cooperative free-space optical communication system with an elastic optical splitter

Author

Liu, Yejun, Wang, Xi, Liao, Shasha, Sun, Qiming, Feng, Shuhua, and Guo, Lei

Abstract

Cooperative communication has been widely studied as an effective technique for free-space optical (FSO) systems to combat the effects of atmospheric conditions and beam misalignment. Related works on cooperative FSO communication mostly used a fixed splitter to uniformly distribute optical power for broadcast transmission, which tends to cause the insufficient utilization of optical power when the relay links have different channel statuses. In this paper, we focus on the optical power utilization of cooperative FSO communication, which remains less touched in previous works, while it is a decisive factor in system performance. We propose an elastic optical splitter structure to improve the efficiency of optical power by dynamically adjusting its optical output to the changing atmospheric channels. The elastic optical splitter brings a new chance for the relay selection and power allocation, which will become a different issue from that in traditional cooperative FSO systems. Thus, we further propose an adaptive relay selection and power allocation scheme using a deep reinforcement learning algorithm. Results demonstrate that the proposed elastic optical splitter is superior to the fixed optical splitter for cooperative FSO communication in bit error rate (BER) by a performance improvement of 1 to 2 orders of magnitude. Along with the proposed adaptive relay selection and power allocation scheme, the performance is further improved by more than 25% under different channel conditions.

Published
2024
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31. A RBF Network for Chinese Text Classification Based on Concept Feature Extraction

Author

Jiang, Minghu, Wang, Lin, Lu, Yinghua, Liao, Shasha, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, King, Irwin, editor, Wang, Jun, editor, Chan, Lai-Wan, editor, and Wang, DeLiang, editor

Published
2006
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32. Concept Features Extraction and Text Clustering Analysis of Neural Networks Based on Cognitive Mechanism

Author

Wang, Lin, Jiang, Minghu, Liao, Shasha, Deng, Beixing, Zong, Chengqing, Lu, Yinghua, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Huang, De-Shuang, editor, Li, Kang, editor, and Irwin, George William, editor

Published
2006
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35. An Improved Method of Feature Selection Based on Concept Attributes in Text Classification

Author

Liao, Shasha, Jiang, Minghu, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Wang, Lipo, editor, Chen, Ke, editor, and Ong, Yew Soon, editor

Published
2005
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37. 高Q值、超窄带宽反向耦合型相移光栅

Author

廖莎莎 Liao Shasha, 黄琮 Huang Cong, 冯玉婷 Feng Yuting, 张伍浩 Zhang Wuhao, 赵帅 Zhao Shuai, and 刘真伟 Liu Zhenwei

Subjects
Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials
Published
2023

38. Temperature determines the shift of thermal neutral zone and influences thermogenic capacity in striped hamsters.

Author

LIAO, Shasha, TAN, Song, JIANG, Meizhi, WEN, Jing, LIU, Jinsong, CAO, Jing, LI, Ming, and ZHAO, Zhijun

Subjects
*HAMSTERS, *CYTOCHROME oxidase, *BROWN adipose tissue, *COLD adaptation, *COLD (Temperature), *ACCLIMATIZATION
Abstract

The thermoneutral zone (TNZ) reflects the adaptation of mammals to their natural habitat. However, it remains unclear how TNZ shifts in response to variations in ambient temperature. To test the hypothesis that ambient temperature plays a key role in determining TNZ variations between seasons, we measured metabolic rate, body temperature, and cytochrome c oxidase (COX) activity of several visceral organs in striped hamsters (Cricetulus barabensis) either acclimated to semi‐natural conditions over a year, or subjected to a gradual decrease in mean temperature from 30 ± 1°C to −15 ± 1°C. The TNZ range in striped hamsters differed seasonally, with a wider TNZ and a lower lower‐critical temperature in winter compared to summer. The hamsters showed a considerable leftward shift of lower‐critical temperature from 30°C to 20°C after the ambient temperature of acclimation from 30°C down to −15°C, whereas the upper‐critical temperature of TNZ remained fixed at 32.5°C. The resting metabolic rate in thermoneutral zone (RMRt), nonshivering thermogenesis (NST), and COX activity of brown adipose tissue, liver, skeletal muscle, brain, and kidneys, increased significantly in hamsters acclimated at lower ambient temperatures. Following acute exposure to 5°C and −15°C, hamsters acclimated to 32.5°C had significantly lower maximal NST and lower serum thyroid tri‐iodothyronine (T3) levels compared to those kept at 23°C. These findings suggest that acclimation to the upper‐critical temperature of TNZ impairs the hamsters' thermogenic capacity to cope with extreme cold temperature. Reduced ambient temperature was mainly responsible for the leftward shift of TNZ in striped hamsters, which reflects the adaptation to cold environments. [ABSTRACT FROM AUTHOR]

Published
2023
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41. A non-isentropic model and the method of characteristic line for the post-detonation expansion of aluminized explosives.

Author

Yuan, Xiaoxia, Wu, Cheng, An, Fengjiang, Liao, Shasha, Zhou, Mingxue, and Xue, Dongyu

Subjects
ISENTROPIC expansion, ALUMINUM oxidation, EXPLOSIVES, DOPPLER velocimetry, ENTROPY
Abstract

The entropy of the flow field could not keep constant due to a strong exothermic reaction of aluminum powders during the post-detonation expansion of the aluminized explosives. Therefore, a non-isentropic model incorporating the aluminum oxidation in the detonation products was established. To solve the non-isentropic expansion process analytically, it was assumed that the whole expansion process was divided into several time ranges and the flow field was isentropic in each time range. Besides, the method of characteristic line was applied to theoretically calculate the velocity of the metal plate driven by aluminized explosives. Moreover, the effects on the pressure, density, sound speed, and temperature of detonation products due to the change of the entropy were analyzed. Finally, the metal plate-pushing tests were conducted to measure the velocity of metal plate driven by aluminized explosives through the Photonic Doppler Velocimetry system, and the degree of aluminum reaction was calculated indirectly from the test results. By comparing the results based on the isentropic model and novel non-isentropic model, it was proved that the non-isentropic model could more correctly describe the driving process of detonation products of aluminized explosives. [ABSTRACT FROM AUTHOR]

Published
2019
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