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Jiahui Zhang,Lili Zhang,Shouyong Zhou,Haiqun Chen,Hui Zhong,Yijiang Zhao,Xin Wang 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5
A magnetically recoverable composite photocatalyst was obtained by introducing TiO2–FexOy hybrid oxide onto the surface of attapulgite via an in-situ deposit technique (marked as ATT–TiO2–FexOy-r, r represents molar ratio of r = nTi/(nTi + nFe)). The obtained composites were carefully characterized and results showed TiO2–FexOy particles with an average size of 10 nm were successfully loaded onto attapulgite fibers’ surface. The FexOy (mixture of Fe2O3 and Fe3O4) acted not only as magnetic source but also took part in the formation of TiO2–Fe2O3 heterojunction structure, which resulted in the obvious absorption in visible light region for the obtained ATT–TiO2–FexOy. The obtained ATT–TiO2–FexOy-r exhibited quite good catalytic activity towards photodegradation of methyl orange under visible light irradiation. The highest degradation ratio and COD removal of methyl orange reached to 94.13% and 90.91% for ATT–TiO2–FexOy-0.5. Moreover, ATT–TiO2–FexOy could be readily recovered and the degradation ratio maintains 83.89% after 5 cycles. Possible mechanism for this enhancement was proposed.
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PLI-VIO: Real-time Monocular Visual-inertial Odometry Using Point and Line Interrelated Features
Jiahui Zhang,Qingzhen Shang,Jinfu Yang,Mingai Li 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.6
As a popular technology, visual-inertial odometry (VIO) has been widely applied in many fields such as autonomous robots and unmanned aerial vehicle (UAV). However, the trade-off between localization accuracy and real-time performance still needs to be optimized. This paper presents a real-time tightly-coupled monocular VIO system using point and line interrelated features (PLI-VIO) under the sliding window optimization framework. In line feature extraction part of PLI-VIO, a line segment extraction and coalescence algorithm based on EDlines is proposed, which extracts line features in real-time without concession on feature quality. At the same time, in order to get efficient and robust line tracking effect, PLI-VIO presents a line-to-point tracking method that fully utilizes the interrelation between point and line. Specifically, line features are divided as a group of points and tracked by pyramidal implementation of Lucas Kanade feature tracker. The proposed line feature tracking method can effectively reduce time consumption on tracking process in a robust way. Extensive evaluations on Euroc and TUM-VI public datasets are performed to demonstrate the preferable performance of our proposed system, and the results show that PLI-VIO obtains better localization accuracy with less computation cost compared against other state-of-the-art VIO algorithms.
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Jiahui Xu,Jingcheng Wang,Jun Rao,Yanjiu Zhong,Shangwei Zhao 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.9
Recent achievements in the field of adaptive dynamic programming (ADP), as well as the data resources and computational capabilities in modern control systems, have led to a growing interest in learning and data-driven control technologies. This paper proposes a twin deterministic policy gradient adaptive dynamic programming (TDPGADP) algorithm to solve the optimal control problem for a discrete-time affine nonlinear system in a modelfree scenario. To solve the overestimation problem resulted from function approximation errors, the minimum value between the double Q network is taken to update the control policy. The convergence of the proposed algorithm in which the value function is served as the Lyapunov function is verified. By designing a twin actor-critic network structure, combining the target network and a specially designed adaptive experience replay mechanism, the algorithm is convenient to implement and the sample efficiency of the learning process can be improved. Two simulation examples are conducted to verify the efficacy of the proposed method.
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Jiahui Jin,Yonghui Liu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.12
Based on epidemic model, a stochastic disturbance propagation model of power grids is proposed in this paper. Firstly, compared with epidemic model, some concepts in power grids are introduced. Then, by analyzing parameters of the nodes, some key nodes are extracted. Hence, the complex power grids are divided into some simple power grids. For the simple power grids, taking Markovian chain into account, the probability of the propagation is solved backward. Combined with the probability and the parameters of the power grids, a model describing importance of the nodes is established. Finally, to demonstrate the effectiveness of the model, an improved clustering algorithm is proposed. The simulation results show that the model has high accuracy in selecting the key nodes. Moreover, it provides an effective method in prediction of power grids.
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Jiahui Liu,Jianyong Yao,Wenxiang Deng 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.4
Electro-hydrostatic actuators (EHAs) have gradually been applied in the flight control systems of multielectric/all-electric aircraft due to the high power-to-volume ratio and the absence of throttling loss as well as overflow loss. However, the existence of high-order dynamics, system nonlinearities, and uncertainties significantly limits the tracking performance of EHAs. This article developed a robust adaptive controller with continuous friction compensation to improve the precise control performance of an EHA with a variable load, nonlinear friction, parametric uncertainties, and unmodeled disturbances. A nonlinear robust control law is used to attenuate various disturbances, and an adaptive law is adopted to cope with parametric uncertainties. Additionally, a continuous friction model is used to describe the friction behavior of an EHA to achieve effective friction compensation and further enhance the motion performance. Moreover, the upper bounds of the matched and mismatched uncertainties can be updated in real-time via adaptive laws, which can reduce design conservatism to some degree. The Lyapunov stability analysis reveals that asymptotic performance can be guaranteed despite the presence of unmodeled disturbances and parametric uncertainties. Furthermore, the applicability of the designed control algorithm with continuous friction compensation is demonstrated with experimental results.
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HS-Sign: A Security Enhanced UOV Signature Scheme Based on Hyper-Sphere
( Jiahui Chen ),( Shaohua Tang ),( Xinglin Zhang ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.6
For “generic” multivariate public key cryptography (MPKC) systems, experts believe that the Unbalanced Oil-Vinegar (UOV) scheme is a feasible signature scheme with good efficiency and acceptable security. In this paper, we address two problems that are to find inversion solution of quadratic multivariate equations and find another structure with some random Oil-Oil terms for UOV, then propose a novel signature scheme based on hyper-sphere (HS-Sign for short) which directly answers these two problems. HS-Sign is characterized by its adding Oil-Oil terms and more advantages compared to UOV. On the one side, HS-Sign is based on a new inversion algorithm from hyper-sphere over finite field, and is shown to be a more secure UOV-like scheme. More precisely, according to the security analysis, HS-Sign achieves higher security level, so that it has larger security parameters choice ranges. On the other side, HS-Sign is beneficial from both the key side and computing complexity under the same security level compared to many baseline schemes. To further support our view, we have implemented 5 different attack experiments for the security analysis and we make comparison of our new scheme and the baseline schemes with simulation programs so as to show the efficiencies. The results show that HS-Sign has exponential attack complexity and HS-Sign is competitive with other signature schemes in terms of the length of the message, length of the signature, size of the public key, size of the secret key, signing time and verification time.
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Jiahui Yuan,Cressler, J.D.,Krithivasan, R.,Thrivikraman, T.,Khater, M.H.,Ahlgren, D.C.,Joseph, A.J.,Jae-Sung Rieh IEEE 2009 IEEE transactions on electron devices Vol.56 No.5
<P>The goal of achieving terahertz (THz) transistors within the silicon material system has generated significant recent interest. In this paper, we use operating temperature as an effective way of gaining a better understanding of the performance limits of SiGe HBTs and their ultimate capabilities for achieving THz speeds. Different approaches for vertical profile scaling and reduction of parasitics are addressed, and three prototype fourth-generation SiGe HBTs are compared and evaluated down to deep cryogenic temperatures, using both dc and ac measurements. A record peak f<SUB>T</SUB>/f<SUB>max</SUB> of 463/618 GHz was achieved at 4.5 K using 130-nm lithography (309/343 GHz at 300 K), demonstrating the feasibility of reaching half-THz f<SUB>T</SUB> and f<SUB>max</SUB> simultaneously in a silicon-based transistor. The BV<SUB>CEO</SUB> of this cooled SiGe HBT was 1.6 V at 4.5 K (BV<SUB>CBO</SUB> = 5.6 V), yielding a record f<SUB>T</SUB> times BV<SUB>CEO</SUB> product of 750 GHzldrV (510 GHzldrV at 300 K). These remarkable levels of transistor performance and the associated interesting device physics observed at cryogenic temperatures in these devices provide important insights into further device scaling for THz speeds at room temperature. It is predicted in a new scaling roadmap that f<SUB>T</SUB>/f<SUB>max</SUB> of room-temperature SiGe HBTs could potentially achieve 782/910 GHz at a BV<SUB>CEO</SUB> of 1.1 V at the 32-nm lithographic node.</P>
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3D Bioprinted GelMA/PEGDA Hybrid Scaffold for Establishing an In Vitro Model of Melanoma
( Jiahui Duan ),( Yanyan Cao ),( Zhizhong Shen ),( Yongqiang Cheng ),( Zhuwei Ma ),( Lijing Wang ),( Yating Zhang ),( Yuchuan An ),( Shengbo Sang ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.4
Due to the high incidence of malignant melanoma, the establishment of in vitro models that recapitulate the tumor microenvironment is of great biological and clinical importance for tumor treatment and drug research. In this study, 3D printing technology was used to prepare GelMA/PEGDA composite scaffolds that mimic the microenvironment of human malignant melanoma cell (A375) growth and construct in vitro melanoma micro-models. The GelMA/PEGDA hybrid scaffold was tested by the mechanical property, cell live/dead assay, cell proliferation assay, cytoskeleton staining and drug loading assay. The growth of tumor cells in two- and three-dimensional culture systems and the anti-cancer effect of luteolin were evaluated using the live/dead staining method and the Cell Counting Kit-8 (CCK-8) method. The results showed a high aggregation of tumor cells on the 3D scaffold, which was suitable for long-term culture. Cytoskeleton staining and immunofluorescent protein staining were used to evaluate the degree of differentiation of tumor cells under 2D and 3D culture systems. The results indicated that 3D bioprinted scaffolds were more suitable for tumor cell expansion and differentiation, and the tumor cells were more aggressive. In addition, luteolin was time- and dose-dependent on tumor cells, and tumor cells in the 3D culture system were more resistant to the drug.
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