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Adaptive Fault-tolerant Control for Trajectory Tracking and Rectification of Directional Drilling
Chi Zhang,Wei Zou,Ningbo Cheng,Junshan Gao 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.1
Motivated by the increasing demands on complex borehole trajectories in oil and gas directional drilling, an adaptive fault-tolerant control (AFTC) method for drilling trajectory tracking and rectification of rotary steerable system (RSS) is proposed by adopting actor-critic reinforcement learning (RL) and integral sliding mode control (ISMC) in the presence of system uncertainties and fault signals. Considering a discrete delay differential equation (DDE) with distance delays, uncertainties and fault signals, first we design an online learning framework via actor-critic RL and radial basis function neural network (RBFNN) in order to make drill bit can track pre-designed trajectory accurately and smoothly. Then in order to handle the fault signals problem, we utilize ISMC to eliminate it as weak as possible and rectify drilling trajectory which may derivate original direction caused by it. The system stability and convergence have been analyzed to ensure uniformly ultimately boundedness of tracking errors and fault-tolerant control signals. The proposed method would have wide application potentials in realizing the trajectory tracking and rectification with automatic operations of directional drilling. The effectiveness and accuracy of it are validated by simulation results with ramp and sine input signals.
Chi He,Zhengping Hao,Xinyan Zhang,Shaokai Gao,Jinsheng Chen 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.5
Mesoporous silica supported catalysts with highly dispersed Pd particles located in their pore channels were synthesized via a novel and simple two-solvents approach. It is found that the support morphology has significant effect on active phase dispersion. Both the pore diameter and pore length of the silica hosts are critical for the catalytic performances of prepared catalysts. Catalyst with plateletlike morphology (Pd/S-P) shows the highest catalytic activity with 90% toluene conversion at 192 8C. The catalytic performances of the synthesized catalysts are closely correlated with Pd dispersion, CO2desorption capability, pore diameter and pore length of the host materials.
Jiali Gao,Chi Wang,Yunbo Hao,Xudong Liang,Kai Zhao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.3
Laser metal deposition process usually involves the nonlinear interaction of multiple factors, such as process parameters and ambient temperature. In this study, random forest (RF) and multilayer back propagation neural network (BPNN) algorithms were employed to investigate the coupling relationship between process parameters and single-track geometry in laser metal deposition for TC11 alloy. With laser power, scanning speed, and powder feeding rate as inputs and track width and height as outputs, 30 different groups of experimental results were adopted as training groups. Their geometries were also predicted. The maximum relative errors of track width and height predictions based on BPNN model were 0.007 % and 0.029 %, respectively, which were lower than those based on RF model. Then, the two models were used to predict the geometry under four new sets of process parameters. Experimental results showed that the maximum error of BPNN model is lower than that of RF model. BPNN model also showed potential to improve cladding quality and efficiency.
Yang, Jie,Gao, Yan,Kim, Jeoung Woo,He, Yujian,Song, Rui,Ahn, Chi Won,Tang, Zhiyong Royal Society of Chemistry 2010 Physical chemistry chemical physics Vol.12 No.38
<P>A partial cation exchange reaction between CdTe nanoparticles and Bi<SUP>3+</SUP> ions gives rise to spontaneous formation of two-dimensional Bi<SUB>2</SUB>Te<SUB>3</SUB>/CdTe nanosheets. The average size and thickness of the nanosheets are around 200 and 6.9 nm, respectively. Both CdTe and Bi<SUB>2</SUB>Te<SUB>3</SUB>, which are there as the form of nanoparticles with average sizes of 3.4 nm, are found to be homogenously distributed in the nanosheets. The Bi<SUB>2</SUB>Te<SUB>3</SUB>/CdTe nanosheets are further integrated into a pellet by using spark plasma sintering for optimizing thermoelectric performance. Compared with the bulk n-type Bi<SUB>2</SUB>Te<SUB>3</SUB>, the pellets composed of Bi<SUB>2</SUB>Te<SUB>3</SUB>/CdTe nanosheets exhibit a considerably low thermal conductivity, 0.63 W m<SUP>−1</SUP> K<SUP>−1</SUP>, and a slightly high Seebeck coefficient, −182.2 μV K<SUP>−1</SUP>, at room temperature.</P> <P>Graphic Abstract</P><P>Two-dimensional Bi<SUB>2</SUB>Te<SUB>3</SUB>/CdTe nanosheets are prepared through a self-reorganization strategy, and they show a rather high thermoelectrical performance. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0cp00079e'> </P>
A Privacy-Preserving Health Data Aggregation Scheme
( Yining Liu ),( Gao Liu ),( Chi Cheng ),( Zhe Xia ),( Jian Shen ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.8
Patients` health data is very sensitive and the access to individual`s health data should be strictly restricted. However, many data consumers may need to use the aggregated health data. For example, the insurance companies needs to use this data to setup the premium level for health insurances. Therefore, privacy-preserving data aggregation solutions for health data have both theoretical importance and application potentials. In this paper, we propose a privacy-preserving health data aggregation scheme using differential privacy. In our scheme, patients` health data are aggregated by the local healthcare center before it is used by data comsumers, and this prevents individual`s data from being leaked. Moreover, compared with the existing schemes in the literature, our work enjoys two additional benefits: 1) it not only resists many well known attacks in the open wireless networks, but also achieves the resilience against the human-factor-aware differential aggregation attack; 2) no trusted third party is employed in our proposed scheme, hence it achieves the robustness property and it does not suffer the single point failure problem.
Zihao Chen,Chi Li,Liping Gao 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.8
Organic matter is widely distributed in soils, which has remarkably influenced geotechnical engineering. The difference of the soil’s structure, chemical constitution, and organic content leads to the distinction of mechanical property. The current research concentrates on the mechanical property of peaty soil and peat, and research on organic soil is rare. Several slope engineering issues show that the rainwater contact with the organic soil layer causes soil landslide, and the mechanism of landslide is that organic matter softens when it soaks the water under the vertical press. Studying the mechanical influence of organic soil with change in moisture content is meaningful because the moisture content of organic soil is much less than that of peat. This study mainly has the following content. The one-dimensional compression test with a variation of organic matter (F) and water (W) is selected to reveal the compression characteristics of organic soil. According to the analysis of the research consequence, the collapsibility with different organic contents and the same void ratio was further analyzed, and the research revealed the influence factor by analyzing the process of the collapse. Burland intrinsic compression theory, which reveals the soil’s structure by analyzing the difference of undisturbed soil and remolded soil, was suitable for the initial moisture content of 1.5 to 2 times the liquid limit but not for organic soil with a moisture content lower than the liquid limit. Therefore, a modified model was provided to widen the range of liquid limit and present the phenomenon of collapse, and good prediction outcome can be obtained based on the linear-regression analysis model and the modified model. A black soil collapsibility model was established based on the experimental results, and it has good prediction outcome.
Han-Lu Gao,Xuan Wang,Hong-Ru Sun,Jun-De Zhou,Shang-Qun Lin,Yu-Hang Xing,Lin Zhu,Hai-Bo Zhou,Ya-Shuang Zhao,Qiang Chi,Yu-Peng Liu 거트앤리버 소화기연관학회협의회 2018 Gut and Liver Vol.12 No.2
Background/Aims: Methylation status plays a causal role in carcinogenesis in targeted tissues. However, the relationship between the DNA methylation status of multiple genes in blood leukocytes and colorectal cancer (CRC) susceptibility as well as interactions between dietary factors and CRC risks are unclear. Methods: We performed a case-control study with 466 CRC patients and 507 cancer-free controls to investigate the association among the methylation status of individual genes, multiple CpG site methylation (MCSM), multiple CpG site heterogeneous methylation and CRC susceptibility. Peripheral blood DNA methylation levels were detected by performing methylation-sensitive high-resolution melting. Results: Total heterogeneous methylation of CA10 and WT1 conferred a significantly higher risk of CRC (adjusted odds ratio [ORadjusted], 5.445; 95% confidence interval [CI], 3.075 to 9.643; ORadjusted, 1.831; 95% CI, 1.100 to 3.047; respectively). Subjects with high-level MCSM (MCSM-H) status demonstrated a higher risk of CRC (ORadjusted, 4.318; 95% CI, 1.529 to 12.197). Additionally, interactions between the high-level intake of fruit and CRH, WT1, and MCSM on CRC were statistically significant. Conclusions: The gene methylation status of blood leukocytes may be associated with CRC risk. MCSM-H of blood leukocytes was associated with CRC, especially in younger people. Some dietary factors may affect hypermethylation status and influence susceptibility to CRC.