914 results on '"Xiaowei Zhao"'
Search Results
902. Model-free semi-active structural control of floating wind turbines
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Mohamed Edrah, Xiaowei Zhao, Xue Xu, Zi Lin, Maurizio Collu, Hongyang Dong, and Abhinav K A
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Wind power ,Adaptive control ,business.industry ,Computer science ,010401 analytical chemistry ,Floating wind turbine ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Dynamical system ,01 natural sciences ,0104 chemical sciences ,Vibration ,Surrogate model ,TA ,Control theory ,Linearization ,Tuned mass damper ,TH ,Quadratic programming ,TJ ,0210 nano-technology ,business - Abstract
This paper addresses the load/vibration reduction problem of offshore floating wind turbines (FWTs). Based on the tuned mass damper (TMD), a novel semi-active control method is designed to mitigate the floating platform’s structural vibration. Different from existing results, the proposed control method is model-free and insensitive to system uncertainties and unmodelled dynamics. We base our design on the model-free adaptive control (MFAC) method. A data-based surrogate model is developed to approximate the unknown FWT dynamical system through the dynamic linearization technique. In addition, a quadratic programming (QP) module is embedded in our MFAC-based semi-active structural controller for constraint handling and control allocation purposes. High-fidelity simulations of FWTs show that our model-free semi-active structural controller can address the limitations of existing results and significantly reduce the platform’s vibration.
903. Vortex moment map for unsteady incompressible viscous flows
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Michael Graham, Juan Li, Xiaowei Zhao, and Yinan Wang
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Physics ,Airfoil ,Chord (geometry) ,Field (physics) ,TL ,Mechanical Engineering ,Applied Mathematics ,Mechanics ,Vorticity ,Condensed Matter Physics ,Vortex shedding ,01 natural sciences ,010305 fluids & plasmas ,Vortex ,Physics::Fluid Dynamics ,Moment (mathematics) ,TA ,Mechanics of Materials ,Condensed Matter::Superconductivity ,0103 physical sciences ,Pitching moment ,010306 general physics - Abstract
In this paper, a vortex moment map (VMM) method is proposed to predict the pitching moment on a body from the vorticity field. VMM is designed to identify the moment contribution of each given vortex in the flow field. Implementing this VMM approach in starting flows of a NACA0012 airfoil, it is found that, due to the rolling up of leading-edge vortices (LEVs) and trailing-edge vortices (TEVs), the unsteady nose-down moment about the quarter chord is higher than the steady-state value. The time variation of the unsteady moment is closely related to the LEVs and TEVs near the body and the VMM gives an intuitive understanding of how each part of the vorticity field contributes to the pitching moment on the body.
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904. MiR-33a Overexpression Exacerbates Diabetic Nephropathy Through Sirt6-dependent Notch Signaling.
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Yingying Wang, Shasha Dai, Jing Yang, Jun Ma, Peng Wang, Xiaowei Zhao, Juan Liu, Ao Xiao, Yahui Song, and Lipin Gao
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DIABETIC nephropathies , *CHRONIC kidney failure , *GENETIC overexpression , *BASAL lamina - Abstract
Introduction. Diabetic nephropathy (DN) belongs to the major cause of end-stage kidney disease. We probed the functions of a microRNA miR-33a in inducing podocytes injury during childhood DN (CDN). Methods. Kidney samples were collected from 20 children with DN. Matrix deposition and glomerular basement membranes thickness were examined by periodic acid-Schiff staining. Immunofluorescence staining was performed to assess kidney function-related proteins. MicroRNA (MiR)-33a mimic together with miR-33a inhibitor was transfected into podocytes for determining the roles of miR-33a. Glomerular podocyte apoptosis was determined by terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) staining along with flow cytometry. Results. Down-regulation of Nephrin and Podocin and increased podocyte apoptosis rate were observed in the glomerulus of CDN as well as podocytes treated with high glucose. MiR-33a was up-regulated in the glomeruli and glucose-treated podocytes. Injury in podocytes was aggravated with miR-33a elevation but alleviated with miR-33a inhibition. Moreover, the expression of Sirtuin 6 (Sirt6) was decreased while the levels of notch receptor 1 (Notch1) and notch receptor 4 (Notch4) were elevated in the glomerulus and glucose-treated podocytes. Decreased level of Sirt6 upon glucose treatment was abrogated by miR-33a inhibition, and the podocytes injury induced by glucose exposure was relieved by Sirt6 via Notch signaling. Conclusion. These findings indicated that miR-33a promoted podocyte injury via targeting Sirt6-dependent Notch signaling in CDN, which might provide a novel sight for CDN treatment. [ABSTRACT FROM AUTHOR]
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- 2024
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905. A Solar Eruption with Relatively Strong Geoeffectiveness Originating from Active Region Peripheral Diffusive Polarities.
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Rui Wang, Ying D. Liu, Huidong Hu, and Xiaowei Zhao
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HELIOSEISMOLOGY ,FLOW velocity ,FERROMAGNETOGRAPHY ,ASTRONOMICAL observations ,COSMIC magnetic fields ,SOLAR active regions - Abstract
We report the observations of a moderate but relatively intense geoeffective solar eruption on 2015 November 4 from the peripheral diffusive polarities of active region 12443. We use space-borne Solar Dynamics Observatory and ACE observations. EUV images identified a helical pattern along a filament channel, and we regard this channel as flux-rope structure. Flow velocity derived from tracked magnetograms infers converging motion along the polarity inversion line beneath the filament channel. An associated magnetic cancellation process was detected in the converging region. Further, the pre-eruptive EUV brightening was observed in the converging region, the most intense part of which appeared in the magnetic cancellation region. These observations imply that the converging and canceling flux probably contributed to the formation of the helical magnetic fields associated with the flux rope. A filament-height estimation method suggests that the middle part of the filament probably lies at a low altitude and was consistent with the initial place of the eruption. A thick current channel associated with the flux rope is also determined. For an expanding thick current channel, the critical height of the decay index for torus instability lies in the range of 37–47 Mm. Southward magnetic fields in the sheath and the ejecta induced a geomagnetic storm with a D
st global minimum of ∼−90 nT. [ABSTRACT FROM AUTHOR]- Published
- 2018
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906. Multi-spacecraft Observations of the Rotation and Nonradial Motion of a CME Flux Rope Causing an Intense Geomagnetic Storm.
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Yi A. Liu, Ying D. Liu, Huidong Hu, Rui Wang, and Xiaowei Zhao
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SPACE vehicles ,ASTRONOMICAL observations ,MAGNETIC storms ,CORONAL mass ejections ,EXTRAPOLATION ,MAGNETIC energy storage - Abstract
We present an investigation of the rotation and nonradial motion of a coronal mass ejection (CME) from AR 12468 on 2015 December 16 using observations from SDO, SOHO, STEREO A, and Wind. The EUV and HMI observations of the source region show that the associated magnetic flux rope (MFR) axis pointed to the east before the eruption. We use a nonlinear force-free field (NLFFF) extrapolation to determine the configuration of the coronal magnetic field and calculate the magnetic energy density distributions at different heights. The distribution of the magnetic energy density shows a strong gradient toward the northeast. The propagation direction of the CME from a Graduated Cylindrical Shell (GCS) modeling deviates from the radial direction of the source region by about 45° in longitude and about 30° in latitude, which is consistent with the gradient of the magnetic energy distribution around the AR. The MFR axis determined by the GCS modeling points southward, which has rotated counterclockwise by about 95° compared with the orientation of the MFR in the low corona. The MFR reconstructed by a Grad–Shafranov (GS) method at 1 au has almost the same orientation as the MFR from the GCS modeling, which indicates that the MFR rotation occurred in the low corona. It is the rotation of the MFR that caused the intense geomagnetic storm with the minimum D
st of −155 nT. These results suggest that the coronal magnetic field surrounding the MFR plays a crucial role in the MFR rotation and propagation direction. [ABSTRACT FROM AUTHOR]- Published
- 2018
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907. Beneficiary Population Analysis of Curative Care Expenditure in Community Health Service Institutions before and after Comprehensive Medical Reform in Beijing
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JIANG Yan, MAN Xiaowei, ZHAO Liying, CHENG Wei
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community health services ,treatment services ,curative care expenditure ,health care costs ,beneficiary groups ,comprehensive medical reform ,Medicine - Abstract
Background It is of great significance to clarify the characteristics of the main population served by community health service institutions for the precise reform of community health service institutions in the next step. Objective To provide accurate data support for the next reform policy formulation and adjustment by analyzing the characteristics of the beneficiary population in terms of curative care expenditure (CCE) in community health service institutions in Beijing before and after the comprehensive reform. Methods The basic data of this study was obtained from the basic database of total health expenditure accounting in Beijing from 2016 to 2019, and other data was obtained from Beijing Health Statistical Yearbook, Beijing Health Financial Statistics Annual Report, and Beijing Health Expenditure Accounting Report from 2016 to 2019. The multi-stage stratified cluster sampling was adopted to select community health service institutions, and the annual out-patient data and in-patient data were included from HIS system. System of Health Accounts 2011 (SHA 2011) was used to calculate and analyze the situation of the beneficiaries of community health service institutions. Results The CCE of community health service institutions in Beijing increased from 12.181 billion yuan to 22.245 billion yuan with an average annual increase of 19.07% from 2016 to 2019. The CCE of middle-aged and elderly patients over 40 years age accounted for more than 92% over the years, and CCE of patients in the age groups of 60s and 80s increased rapidly, with an average annual growth rate of 24.08% and 25.84%, respectively. Among the CCE, endocrine, nutritional and metabolic diseases, abnormal symptoms, signs and test results, circulatory system diseases accounted for the highest proportion. The CCE of endocrine, nutritional and metabolic diseases, nervous system diseases, abnormal symptoms, signs and test results increased rapidly, with an average annual growth rate of 40.11%, 48.40% and 32.43%, respectively. Conclusion The effectiveness of hierarchical diagnosis and treatment has begun to emerge after the comprehensive reform. Community medical service resources in Beijing are mainly consumed by middle-aged and elderly patients and patients with chronic non-communicable diseases such as endocrine and circulatory diseases. The comprehensive reforms guided more middle-aged and elderly people and patients with chronic diseases to community health service institutions. Community health service institutions should improve their service capacities in many aspects, such as service capacity, human resource, chronic disease management and medical consortium construction, to consolidate and maintain the effectiveness of the reform.
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- 2024
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908. Intelligent wind farm control via deep reinforcement learning and high-fidelity simulations
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Hongyang Dong, Xiaowei Zhao, and Jincheng Zhang
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Wind power ,Computer science ,business.industry ,020209 energy ,Mechanical Engineering ,TK ,02 engineering and technology ,Building and Construction ,Management, Monitoring, Policy and Law ,Q1 ,Turbine ,Offshore wind power ,General Energy ,Electricity generation ,020401 chemical engineering ,TA ,Control theory ,Robustness (computer science) ,Control system ,0202 electrical engineering, electronic engineering, information engineering ,Reinforcement learning ,TJ ,0204 chemical engineering ,business - Abstract
Wind farms’ power-generation efficiency is constrained by the high system complexity. A novel deep reinforcement learning (RL)-based wind farm control scheme is proposed to handle this challenge and achieve power generation optimization. A reward regularization (RR) module is designed to estimate wind turbines’ normalized power outputs under different yaw settings and uncertain wind conditions, which brings strong robustness and adaptability to the proposed control scheme. The RR module is then combined with the deep deterministic policy gradient algorithm to evaluate the optimal yaw settings for all the wind turbines within the farm. The proposed wind farm control scheme is data-driven and model-free, which addresses the limitations of current approaches, including reliance on accurate analytical/parametric models and lack of adaptability to uncertain wind conditions. In addition, a novel composite learning-based controller for each turbine is designed to achieve closed-loop yaw tracking, which can guarantee the exponential convergence of tracking errors in the presence of uncertainties of yaw actuators. The whole control system can be pre-trained offline and fine-tuned online, providing an easy-to-apply solution with enhanced generality and flexibility for wind farms. High-fidelity simulations with SOWFA (simulator for offshore wind farm applications) and Tensorflow show that the proposed scheme can significantly improve the wind farm’s power generation by exploiting a sparse data set without requiring any wake model.
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909. Propagation and Interaction Properties of Successive Coronal Mass Ejections in Relation to a Complex Type II Radio Burst.
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Ying D. Liu, Xiaowei Zhao, and Bei Zhu
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CORONAL mass ejections , *SOLAR radio bursts , *MAGNETOHYDRODYNAMICS , *SOLAR activity , *RADIO astronomy - Abstract
We examine the propagation and interaction properties of three successive coronal mass ejections (CMEs) from 2001 November 21–22, with a focus on their connection with the behaviors of the associated long-duration complex type II radio burst. In combination with coronagraph and multi-point in situ observations, the long-duration type II burst provides key features for resolving the propagation and interaction complexities of the three CMEs. The two CMEs from November 22 interacted first and then overtook the November 21 CME at a distance of about 0.85 au from the Sun. The timescale for the shock originally driven by the last CME to propagate through the preceding two CMEs is estimated to be about 14 and 6 hr, respectively. We present a simple analytical model without any free parameters to characterize the whole Sun-to-Earth propagation of the shock, which shows a remarkable consistency with all the available data and MHD simulations even out to the distance of Ulysses (2.34 au). The coordination of in situ measurements at the Earth and Ulysses, which were separated by about 71.°4 in latitude, gives important clues for the understanding of shock structure and the interpretation of in situ signatures. The results also indicate a means by which to increase geo-effectiveness with multiple CMEs, which can be considered as another manifestation of the “perfect storm” scenario proposed by Liu et al., although the current case is not “super” in the same sense as the 2012 July 23 event. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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910. Propagation Characteristics of Two Coronal Mass Ejections from the Sun Far into Interplanetary Space.
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Xiaowei Zhao, Ying D. Liu, Huidong Hu, and Rui Wang
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STELLAR corona , *STELLAR mass , *INTERPLANETARY medium , *MAGNETIC storms , *MAGNETOHYDRODYNAMIC waves - Abstract
Propagation of coronal mass ejections (CMEs) from the Sun far into interplanetary space is not well understood, due to limited observations. In this study we examine the propagation characteristics of two geo-effective CMEs, which occurred on 2005 May 6 and 13, respectively. Significant heliospheric consequences associated with the two CMEs are observed, including interplanetary CMEs (ICMEs) at the Earth and Ulysses, interplanetary shocks, a long-duration type II radio burst, and intense geomagnetic storms. We use coronagraph observations from SOHO/LASCO, frequency drift of the long-duration type II burst, in situ measurements at the Earth and Ulysses, and magnetohydrodynamic propagation of the observed solar wind disturbances at 1 au to track the CMEs from the Sun far into interplanetary space. We find that both of the CMEs underwent a major deceleration within 1 au and thereafter a gradual deceleration when they propagated from the Earth to deep interplanetary space, due to interactions with the ambient solar wind. The results also reveal that the two CMEs interacted with each other in the distant interplanetary space even though their launch times on the Sun were well separated. The intense geomagnetic storm for each case was caused by the southward magnetic fields ahead of the CME, stressing the critical role of the sheath region in geomagnetic storm generation, although for the first case there is a corotating interaction region involved. [ABSTRACT FROM AUTHOR]
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- 2017
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911. Proteomics and pathway analysis of N-glycosylated mammary gland proteins in response to Escherichia coli mastitis in cattle.
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Yongxin Yang, Weijun Shen, Xiaowei Zhao, Huiling Zhao, Dongwei Huang, and Guanglong Cheng
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MAMMARY glands , *CATTLE diseases research , *BOVINE mastitis , *ESCHERICHIA coli , *GLYCOSYLASES - Abstract
The aim of this study was to investigate the N-linked glycosylated protein profile of mammary tissue from healthy cows and cows with mastitis due to Escherichia coli, in order to understand the molecular mechanisms of the host response to mastitis. N-glycopeptides were enriched with a lectin mixture and identified through high-accuracy mass spectrometry. A total of 551 N-glycosylation sites, corresponding to 294 proteins, were identified in the mammary tissues of healthy cows; these glycoproteins were categorised into three functional groups and clustered into 11 specific pathways. A total of 511 N-glycosylation sites, corresponding to 283 glycosylated proteins, were detected in the mammary tissues of cows with E. coli mastitis. There were differences in N-glycosylation sites in 98 proteins in the mammary tissues of healthy cows and cows with mastitis due to E. coli. Most proteins with altered glycosylation were those involved in responses to stress, cell adhesion and the immune response, and were assigned to five specific pathways based on their gene ontology annotation. The results from this study show that the glycosylated protein profile in the mammary tissues of healthy and mastitic cows are different, and altered glycoproteins are associated with several pathways, including the lysosome and O-glycan biosynthesis pathways. [ABSTRACT FROM AUTHOR]
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- 2014
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912. Evaluating Unsteady Fluid Dynamic Forces in Viscous Flows from the Vorticity Field.
- Author
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Juan Li, Yinan Wang, Graham, Michael, and Xiaowei Zhao
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The vortex force map (VFM) method is a promising low-cost technique for predicting unsteady aerodynamic load from the vorticity field. Developed under potential flow assumption and applied to high-resolution computational fluid dynamics (CFD) data, the original VFM method needs to be further explored for viscous flows, especially at low Reynolds numbers and with incomplete knowledge of the flow data. In this paper, the VFM method is extended to general viscous flows, with both forces contributed from vorticity in the flowfield and on the body surface considered. We find that viscosity contributes to not only the skin-friction force but also a pressure force term. We also show that the extended vortex pressure force maps for general flow problems without the potential flow assumption lead to vanishing contributions from the far-field. The extended VFM method is applied to CFD flowfields for the starting flow of a cylinder and a NACA0012 airfoil, and it is used to analyze the force contribution effect of a given vortex. Moreover, acceptable accuracy of the method on truncated domains and under coarse sampling of typical particle image velocimetry measurement size is demonstrated. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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913. Bioinformatics Resources and Tools for Conformational B-Cell Epitope Prediction.
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Pingping Sun, Haixu Ju, Zhenbang Liu, Qiao Ning, Jian Zhang, Xiaowei Zhao, Yanxin Huang, Zhiqiang Ma, and Yuxin Li
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Identification of epitopeswhich invoke strong humoral responses is an essential issue in the field ofimmunology. Localizing epitopes by experimental methods is expensive in terms of time, cost, and effort; therefore, computational methods feature for its low cost and high speed was employed to predict B-cell epitopes. In this paper, we review the recent advance of bioinformatics resources and tools in conformational B-cell epitope prediction, including databases, algorithms, web servers, and their applications in solving problems in related areas. To stimulate the development of better tools, some promising directions are also extensively discussed. [ABSTRACT FROM AUTHOR]
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- 2013
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914. A Structured Skin Care Protocol for Preventing and Treating Incontinence-associated Dermatitis in Critically Ill Patients.
- Author
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Zhang X, Wang X, Zhao X, and Zhang Y
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- Adolescent, Critical Illness, Humans, Intensive Care Units, Skin Care methods, Dermatitis etiology, Dermatitis prevention & control, Fecal Incontinence
- Abstract
Objective: To examine the effectiveness of a structured skin care protocol for preventing and treating incontinence-associated dermatitis (IAD) in critically ill patients., Methods: Participants were drawn from the ICUs of three teaching hospitals between January 2016 and December 2017. Patients were eligible if they were ≥18 years old, had idiopathic fecal incontinence, had diarrhea but were unable to sense it, and were expected to stay in the ICU for at least 72 hours after developing incontinence. A total of 143 patients were enrolled: 79 in the experimental group and 64 in the control group. In the first phase of the study, routine skin care measures were used; in the second phase, three ICU caregivers were trained to provide a structured skin care protocol. Trained research team members conducted the data collection and analysis. The TREND (Transparent Reporting of Evaluations with Nonrandomized Designs) Statement Checklist was followed in reporting the study results., Results: Application of the structured skin care protocol reduced the incidence of IAD from 35.9% in the control phase to 17.7% in the intervention phase (χ2 = 6.117, P < .05) and also decreased the severity of IAD (z = -2.023, P < .05). Further, IAD developed later (z = -2.116, P < .05) in the intervention group than in the control group. In addition, the nursing times to prevent or manage IAD did not differ significantly between the groups (t = -0.258, P > .05; t = -1.190, P > .05)., Conclusions: Use of the developed structured skin care protocol for IAD in critically ill patients lowered the incidence and severity of IAD and delayed IAD development., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)
- Published
- 2022
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