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27 results on '"Chen, Zhitian"'

4. Littlewood-Paley Characterization for Musielak-Orlicz-Hardy Spaces Associated with Operators

Author

Shen, Jiawei, Chen, Zhitian, and Long, Shunchao

Subjects
Mathematics - Classical Analysis and ODEs, Mathematics - Analysis of PDEs, 42B20, 42B25, 42B30, 42B35, 46E30, 47B38
Abstract

Let $X$ be a space of homogeneous type. Assume that $L$ is an non-negative second-order self-adjoint operator on $L^2\left(X\right)$ with (heart) kernel associated to the semigroup $e^{ - tL}$ that satisfies the Gaussian upper bound. In this paper, the authors introduce a new characterization of the Musielak-Orlicz-Hardy Space $H_{\varphi, L}\left(X\right)$ associated with $L$ in terms of the Lusin area function where $\varphi$ is a growth function. Further, the authors prove that the Musielak-Orlicz-Hardy Space $H_{L,G,\varphi}\left(X\right)$ associated with $L$ in terms of the Littlewood-Paley function is coincide with $H_{\varphi, L}\left(X\right)$ and their norms are equivalent.

Published
2019

6. Adaptive Visual Control for Robotic Manipulators with Consideration of Rigid-Body Dynamics and Joint-Motor Dynamics.

Author

Chen, Zhitian, Wen, Weijian, and Yang, Weijun

Subjects
*ROBOT dynamics, *CASCADE control, *RADIAL basis functions, *CLOSED loop systems, *APPROXIMATION error
Abstract

A novel cascade visual control scheme is proposed to tailor for electrically driven robotic manipulators that operate under kinematic and dynamic uncertainties, utilizing an uncalibrated stationary camera. The proposed control approach incorporates adaptive weight radial basis function neural networks (RBFNNs) to learn the behaviors of the uncertain dynamics of the robot and the joint actuators. The controllers are designed to nullify the approximation error and mitigate unknown disturbances through an integrated robust adaptive mechanism. A major advantage of the proposed approach is that prior knowledge of the dynamics of the robotic manipulator and its actuator is no longer required. The controller autonomously assimilates the robot and actuator dynamics online, thereby obviating the need for fussy regression matrix derivation and advance dynamic measurement to establish the adaptive dynamic parameter update algorithm. The proposed scheme ensures closed-loop system stability, bounded system states, and the convergence of tracking errors to zero. Simulation results, employing a PUMA manipulator as a testbed, substantiate the viability of the proposed control policy. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Novel Chemiluminescence Immunoassay (CLIA) for the Sensitive Determination of Kidney Injury Molecule-1 in Human Urine.

Author

Li, Lanya, Yang, Zhiqiang, Lin, Jiayuan, Chen, Zhitian, Zhang, Bo, and Fu, Xiaoling

Subjects
CHEMILUMINESCENCE immunoassay, KIDNEY injuries, URINE, ALKALINE phosphatase, MAGNETIC separation, DIAGNOSIS
Abstract

Kidney injury molecule 1 (KIM-1) is markedly upregulated in the proximal tubule after injury and is maladaptive when chronically expressed. A practical sensitive chemiluminescence immunoassay combined with magnetic bead separation for the determination of KIM-1 in human urine has been developed. Based on a sandwich-type immunoassay, the analyte is captured by the monoclonal antibodies (mAb) coated in magnetic beads and those labeled with the alkaline phosphatase. The changes of KIM-1 concentration levels were monitored by the CLIA for the early diagnosis of kidney disease. The established immunoassay exhibited a wide linear range from 0.5 to 81 ng/mL with a detection limit of 0.17 ng/mL. The recoveries, specificity, and interference results of the developed method were satisfactory. The whole analysis time was 30 min. The developed method was for the detection of kidney disease in patients. This work is a novel chemiluminescence immunoassay with excellent performance for the early diagnosis of kidney diseases. [ABSTRACT FROM AUTHOR]

Published
2023
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17. Spiral Bragg gratings for TM mode silicon photonics

Author

Chen, Zhitian

Subjects
Physics::Optics
Abstract

In this thesis, we demonstrate long transverse magnetic (TM) Bragg gratings wrapped compactly using spiral waveguides on the silicon-on-insulator (SOI) platform. We developed three types of TM spiral Bragg grating waveguides (SBGWs) including uniform spiral Bragg grating (U-SBGWs), phaseshifted spiral Bragg grating (P-SBGWs), and chirped spiral Bragg gratings (C-SBGWs). Our spiral waveguides are space-efficient, requiring an area of only 189 x 189 μm² to accommodate 1 cm long Bragg grating waveguides and, thus, are less susceptible to fabrication non-uniformities. Due to these factors, the TM U-SBGWs are able to successfully obtain narrow bandwidths and high extinction ratios (ERs), as narrow as 0.09 nm and as large as 52 dB respectively. Also, the TM P-SBGWs can obtain sharp resonance peaks with high quality factors of 78790. Finally, we demonstrate the TM C-SBGWs, which exhibit group delays that are linear functions of the wavelengths over their passbands. Traditionally, due to the large coupling coefficients and the flexibility for achieving desired spectral characteristics, short Bragg grating waveguides for transverse electric (TE) modes on the SOI platform have been developed for applications in optical communication and sensing systems. In contrast, TM modes Bragg gratings on SOI platform have small coupling coefficients and, therefore, the grating lengths need to be much longer than TE mode devices, in order to obtain large ERs. However, such TM mode Bragg gratings can achieve very narrow bandwidths. Creating long gratings in regular straight waveguides suffer from the fabrication non-uniformity effects caused by the wafer thickness. As is shown here, spiral-shaped waveguides can be used to increase the grating length, while still being made using little on chip real estate, thus reducing the effects of fabrication non-uniformity.

Published
2015
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22. Sinusoidal Anti-coupling SOI Strip Waveguides

Author

Zhang, Fan, primary, Yun, Han, additional, Donzella, Valentina, additional, Lu, Zeqin, additional, Wang, Yun, additional, Chen, Zhitian, additional, Chrostowski, Lukas, additional, and Jaeger, Nicolas A. F., additional

Published
2015
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