| 1. |
- Gao, Shigen, et al.
(författare)
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Fuzzy adaptive automatic train operation control with protection constraints : A residual nonlinearity approximation-based approach
- 2020
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Ingår i: Engineering applications of artificial intelligence. - : Elsevier BV. - 0952-1976 .- 1873-6769. ; 96
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we present fuzzy adaptive control based on residual nonlinearity approximation in the presence of protection constraints for the target trajectory tracking problem observed in automatic train operation. Herein, protection constraints refer to a condition wherein the speed and position of a controlled train are not allowed to surpass the boundaries imposed by automatic train protection and moving authority. By defining proper coordinate transformation, the protection constraints are converted to an error-prescribed performance control problem that facilitates operational efficiency by reducing the margin with respect to target trajectories. Based on the prescribed performance control methodology, we present an improved scheme using fuzzy residual nonlinearity approximation and establish the uniformly ultimately boundedness (UUB) property. A novel feature therein is that the ultimate boundary of the proposed scheme is simultaneously characterized by the prescribed performance functions and control parameters, with rigorous and analytically mathematical expressions; while pioneering the prescribed performance control methodology, the ultimate boundary is characterized solely by the prescribed performance functions. To verify the effectiveness and advantages of the proposed scheme, the controllers are applied to the automatic train operation on the Beijing Yizhuang line, which contains 13 operational intervals. Finally, comparative and simulation results are presented to validate the proposed method.
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| 2. |
- Gao, Shigen, et al.
(författare)
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High-Speed Trains Automatic Operation with Protection Constraints : A Resilient Nonlinear Gain-based Feedback Control Approach
- 2019
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Ingår i: IEEE-CAA JOURNAL OF AUTOMATICA SINICA. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2329-9266. ; 6:4, s. 992-999
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Tidskriftsartikel (refereegranskat)abstract
- This paper addresses the control design for automatic train operation of high-speed trains with protection constraints. A new resilient nonlinear gain-based feedback control approach is proposed, which is capable of guaranteeing, under some proper non-restrictive initial conditions, the protection constraints control raised by the distance-to-go (moving authority) curve and automatic train protection in practice. A new hyperbolic tangent function-based model is presented to mimic the whole operation process of high-speed trains. The proposed feedback control methods are easily implementable and computationally inexpensive because the presence of only two feedback gains guarantee satisfactory tracking performance and closed-loop stability, no adaptations of unknown parameters, function approximation of unknown nonlinearities, and attenuation of external disturbances in the proposed control strategies. Finally, rigorous proofs and comparative simulation results are given to demonstrate the effectiveness of the proposed approaches.
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| 3. |
- Nan, Hairong, et al.
(författare)
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Serum uric acid and components of the metabolic syndrome in non-diabetic populations in Mauritian Indians and Creoles and in Chinese in Qingdao, China.
- 2008
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Ingår i: Metabolic syndrome and related disorders. - : Mary Ann Liebert Inc. - 1557-8518 .- 1540-4196. ; 6:1, s. 47-57
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To assess the association of serum uric acid (UA) with components of metabolic syndrome (MetS) in different ethnic groups. METHODS: Nondiabetic men (3285) and nondiabetic women (4078) aged 25 to 74 years without a history of cardiovascular disease and gout from Mauritius and Qingdao China, comprising Mauritian Indians, Mauritian Creoles, and an urban Chinese population, were studied. The top quintile of waist circumference, body mass index (BMI), blood pressure, serum total cholesterol and triglycerides, plasma glucose levels, and the bottom quintile of HDL cholesterol was defined as the metabolic disorder. Hyperuricemia was defined if UA values were in the top quintile. RESULTS: In a multivariate model (adjusted for age, cohort, smoking, and alcohol consumption), waist circumference, BMI, and serum triglycerides appeared to be independently associated with hyperuricemia in both sexes and in all ethnic groups except in Chinese women. Multivariate adjusted odds ratios (95% confidence intervals [CIs]) for having three or more metabolic disorders vs fewer than three, corresponding to a one SD increase in serum UA concentration, were 1.75 (1.51 to 2.02), 2.19 (1.71 to 2.82) and 2.30 (1.68 to 3.16) in Indian, Creole, and Chinese men, respectively, and 1.74 (1.52 to 2.00), 1.75 (1.40 to 2.19) and 1.72 (1.37 to 2.16) in Indian, Creole, and Chinese women, respectively. CONCLUSIONS: In nondiabetics of Asian and African ancestry, elevated serum UA was closely associated with components of MetS, but whether UA provides additional information to the definition of the MetS in predicting future cardiovascular disease and diabetes needs to be studied.
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| 4. |
- Yang, Xiaoxia, et al.
(författare)
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Guided crowd dynamics via modified social force model
- 2014
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Ingår i: Physica A. - : Elsevier BV. - 0378-4371 .- 1873-2119. ; 411, s. 63-73
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Tidskriftsartikel (refereegranskat)abstract
- Pedestrian dynamics is of great theoretical significance for strategy design of emergency evacuation. Modification of pedestrian dynamics based on the social force model is presented to better reflect pedestrians' behavioral characteristics in emergency. Specifically, the modified model can be used for guided crowd dynamics in large-scale public places such as subway stations and stadiums. This guided crowd model is validated by explicitly comparing its density-speed and density-flow diagrams with fundamental diagrams. Some social phenomena such as gathering, balance and conflicts are clearly observed in simulation, which further illustrate the effectiveness of the proposed modeling method. Also, time delay for pedestrians with time-dependent desired velocities is observed and explained using the established model in this paper. Furthermore, this guided crowd model is applied to the simulation system of Beijing South Railway Station for predictive evacuation experiments.
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| 5. |
- Yu, Xia, et al.
(författare)
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Wild-Type and Non-Wild-Type Mycobacterium tuberculosis MIC Distributions for the Novel Fluoroquinolone Antofloxacin Compared with Those for Ofloxacin, Levofloxacin, and Moxifloxacin
- 2016
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Ingår i: Antimicrobial Agents and Chemotherapy. - : AMER SOC MICROBIOLOGY. - 0066-4804 .- 1098-6596. ; 60:9, s. 5232-5237
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Tidskriftsartikel (refereegranskat)abstract
- Antofloxacin (AFX) is a novel fluoroquinolone that has been approved in China for the treatment of infections caused by a variety of bacterial species. We investigated whether it could be repurposed for the treatment of tuberculosis by studying its in vitro activity. We determined the wild-type and non-wild-type MIC ranges for AFX as well as ofloxacin (OFX), levofloxacin (LFX), and moxifloxacin (MFX), using the microplate alamarBlue assay, of 126 clinical Mycobacterium tuberculosis strains from Beijing, China, of which 48 were OFX resistant on the basis of drug susceptibility testing on Lowenstein-Jensen medium. The MIC distributions were correlated with mutations in the quinolone resistance-determining regions of gyrA (Rv0006) and gyrB (Rv0005). Pharmacokinetic/pharmacodynamic (PK/PD) data for AFX were retrieved from the literature. AFX showed lower MIC levels than OFX but higher MIC levels than LFX and MFX on the basis of the tentative epidemiological cutoff values (ECOFFs) determined in this study. All strains with non-wild-type MICs for AFX harbored known resistance mutations that also resulted in non-wild-type MICs for LFX and MFX. Moreover, our data suggested that the current critical concentration of OFX for Lowenstein-Jensen medium that was recently revised by the World Health Organization might be too high, resulting in the misclassification of phenotypically non-wildtype strains with known resistance mutations as wild type. On the basis of our exploratory PK/PD calculations, the current dose of AFX is unlikely to be optimal for the treatment of tuberculosis, but higher doses could be effective.
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| 6. |
- Zhou, Min, et al.
(författare)
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Modeling and Simulation of Crowd Evacuation With Signs at Subway Platform : A Case Study of Beijing Subway Stations
- 2022
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Ingår i: IEEE transactions on intelligent transportation systems (Print). - : Institute of Electrical and Electronics Engineers (IEEE). - 1524-9050 .- 1558-0016. ; 23:2, s. 1492-1504
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Tidskriftsartikel (refereegranskat)abstract
- Emergency signage systems provide effective route guidance and evacuation information for pedestrians in case of emergencies such as fire, blackout, and explosion. This paper proposes a modified social force (SF) model to investigate crowd evacuation dynamics taking into account the influence of emergency signs. The perceiving probability model is formulated for the quantitative description of the probability that pedestrians can successfully notice the sign and clearly perceive the guidance information. Simulation experiments and controlled experiments are designed to calibrate the parameters of the proposed model. The effectiveness of the modified SF model is preliminarily verified by comparing the simulation results with experimental data and/or empirical results such as fundamental diagrams and self-organization phenomena. A case study of crowd evacuation simulations at a typical Beijing subway station is conducted to evaluate evacuation performance of three signage distribution schemes, i.e., Maximal Covering (MaxCover), Uniform, and Random, which are proposed by the maximal covering location and empirical approaches, as well as contrasted scheme without emergency signs. The effects of the quantity and distribution of emergency signs on crowd evacuation efficiency are studied quantitatively by simulations. The results show that installing emergency signs can improve evacuation efficiency no matter what distribution scheme is adopted. By choosing an appropriate distribution scheme i.e., MaxCover, the evacuation performance can be further improved and the evacuation time can be significantly reduced.
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