GLORIA

GEOMAR Library Ocean Research Information Access

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • SAGE Publications  (17)
  • Li, Xiang  (17)
Material
Publisher
  • SAGE Publications  (17)
Language
Years
Subjects(RVK)
  • 1
    Online Resource
    Online Resource
    SAGE Publications ; 2016
    In:  Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering Vol. 230, No. 6 ( 2016-12), p. 486-497
    In: Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, SAGE Publications, Vol. 230, No. 6 ( 2016-12), p. 486-497
    Abstract: The problem of trajectory tracking for a class of nonlinear systems in the presence of un-modeled dynamics, parameter variations and even the actuator faults is investigated in this paper. A novel fault-tolerant control scheme is proposed by combining the nominal model-based controller and time-delay controller, which are adopted to achieve the real-time dynamic compensation and guarantee the robust stability of the controlled systems, respectively. Moreover, high-quality differential signals are unavailable in the presence of disturbances and measurement noise, which limit the performance of closed-loop systems in practice. Therefore, an extended state observer (ESO) is introduced to obtain high-quality differential signal estimations based on position measurements only. Furthermore, the effectiveness of the proposed novel control scheme is verified by testing in the spacecraft attitude tracking system.
    Type of Medium: Online Resource
    ISSN: 0954-4089 , 2041-3009
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2016
    detail.hit.zdb_id: 2024897-0
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    Online Resource
    Online Resource
    SAGE Publications ; 2018
    In:  Transactions of the Institute of Measurement and Control Vol. 40, No. 3 ( 2018-02), p. 968-986
    In: Transactions of the Institute of Measurement and Control, SAGE Publications, Vol. 40, No. 3 ( 2018-02), p. 968-986
    Abstract: A redundant electro-hydraulic shaking table (REST) of six degrees-of-freedom (6 DOFs) with eight hydraulic actuators is an essential experimental tool in many industrial applications for real-time simulation of actual vibrations, such as structural vibration, earthquake simulation and fatigue testing. In order to obtain a high-fidelity acceleration waveform on the REST, a feed-forward inverse model (FFIM) controller with a modelling error compensator is proposed in this study. A recursive extended least-squares algorithm is employed to identify an acceleration closed-loop transfer function of the REST. A zero phase error compensation technology is employed to guarantee stability of the designed FFIM because the identified acceleration closed-loop transfer function is a typical non-minimum phase system and its direct inverse transfer function is unstable. The modelling error compensator is designed to compensate for the modelling error between the identified transfer function and the actual experimental REST, which deteriorates the acceleration waveform replication accuracy of the REST. A 6 DOF REST experimental system was used to verify the proposed controller. Experimental results demonstrated that the proposed controller gave satisfactory acceleration tracking performances on the REST.
    Type of Medium: Online Resource
    ISSN: 0142-3312 , 1477-0369
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
    detail.hit.zdb_id: 2025882-3
    SSG: 3,2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Online Resource
    Online Resource
    SAGE Publications ; 2016
    In:  International Journal of Advanced Robotic Systems Vol. 13, No. 5 ( 2016-09-01), p. 172988141666253-
    In: International Journal of Advanced Robotic Systems, SAGE Publications, Vol. 13, No. 5 ( 2016-09-01), p. 172988141666253-
    Abstract: An electrohydraulic shaking table is an essential experimental facility in many industrial applications to real-time simulate actual vibration situations including structural vibration and earthquake. However, there is still a challenging area for its acceleration waveform replication because acceleration output responses of the electrohydraulic shaking table would not be as intended in magnitude and phase of an acceleration closed-loop system due to inherent hydraulic nonlinear dynamics of electrohydraulic servo systems. Thus, how to accurately and coordinately control parallel hydraulic actuators of the electrohydraulic shaking table is a critical issue; so, many control techniques have been developed to address the issue. Some currently used key techniques in this field are reviewed in the article, which are the objectives of academic investigations and industrial applications. The article reviews some new control algorithms for the electrohydraulic shaking table to obtain high-fidelity acceleration waveform replication accuracy.
    Type of Medium: Online Resource
    ISSN: 1729-8814 , 1729-8814
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2016
    detail.hit.zdb_id: 2202393-8
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    In: European Journal of Inflammation, SAGE Publications, Vol. 18 ( 2020-01), p. 205873922093503-
    Abstract: To analyse the differential indicators of COVID-19 in severe and mild cases and to study the factors affecting the immune function of patients and the time required for oropharyngeal swabs to become negative. Age, albumin (ALB) levels, prealbumin (PAB) levels, high-sensitivity C-reactive protein (hs-CRP) levels, platelet counts, lymphocyte counts, neutrophil counts, CD3+, CD4+, CD8+ T cell counts and the time for oropharyngeal swabs to become negative were collected from 37 patients with COVID-19; the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) were calculated as indicators of inflammation. An independent-sample t test was used to analyse differences between the severe and mild groups, and factors affecting the CD3+, CD4+ and CD8+ T cell counts and the time for the nucleic acid tests of oropharyngeal to convert to negative were identified by single-factor and multifactor analyses. Lymphocyte, ALB, PAB, CD3+, CD4+ and CD8+ T cell levels in the severe group were lower than those in the mild group, the P values were 0.048, 0.004, 0.033, 0.033, 0.015 and 0.013, respectively. The neutrophil count and PLR were higher in the severe group compared with that in the patients of mild group; the P values were all 0.000. Single-factor analysis showed that age, ALB level, PAB level, hs-CRP level, platelet count, the NLR, the PLR and the time to a negative nucleic acid test were the main factors influencing CD3+ T cells; the P values were 0.001, 0.031, 0.001, 0.010, 0.005, 0.002, 0.000 and 0.048, respectively. Age, ALB level, PAB level, hs-CRP level, platelet count, the NLR, the PLR and time to a negative nucleic acid test were the main factors influencing CD8+ T cells; the P values were 0.000, 0.012, 0.000, 0.005, 0.002, 0.004, 0.005 and 0.003, respectively. Age, PAB level, hs-CRP level, platelet count, the NLR and the PLR were the main factors influencing CD4+ T cells; the P values were 0.001, 0.006, 0.030, 0.041, 0.005 and 0.001, respectively. Age, ALB level, PAB level, hs-CRP level, platelet count, the NLR, CD3+ T cell count and CD8+ T cell count were the main factors influencing the time to a negative nucleic acid test in oropharyngeal swabs, and the P values were 0.032, 0.043, 0.013, 0.016, 0.042, 0.049, 0.048 and 0.003, respectively. Multivariate analysis showed that the PLR and platelet count were the main factors influencing CD3+ T cells. The P values were all 0.000. The PLR and platelet count were the main factors influencing CD4+ T cells. The P values were 0.000 and 0.001, respectively. The PLR and platelet count were also the main factors influencing CD8+ T cells. The P values were 0.004 and 0.001. CD8+ T cells affected the time to a negative nucleic acid test in oropharyngeal swab samples, and the P value was 0.002. There were differences in the PLR, PAB level, ALB level and T cells between the severe and mild groups. The platelet count and PLR were the main factors influencing the immune function of patients with COVID-19, and CD8+ T cells influenced the negative conversion time of the nucleic acid test in oropharyngeal swabs.
    Type of Medium: Online Resource
    ISSN: 2058-7392 , 2058-7392
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
    detail.hit.zdb_id: 2584683-8
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    Online Resource
    Online Resource
    SAGE Publications ; 2016
    In:  Advances in Mechanical Engineering Vol. 8, No. 4 ( 2016-04-01), p. 168781401664544-
    In: Advances in Mechanical Engineering, SAGE Publications, Vol. 8, No. 4 ( 2016-04-01), p. 168781401664544-
    Type of Medium: Online Resource
    ISSN: 1687-8140 , 1687-8140
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2016
    detail.hit.zdb_id: 2501620-9
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 6
    Online Resource
    Online Resource
    SAGE Publications ; 2014
    In:  Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering Vol. 228, No. 9 ( 2014-10), p. 722-733
    In: Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering, SAGE Publications, Vol. 228, No. 9 ( 2014-10), p. 722-733
    Abstract: In this article, a combined control strategy incorporating off-line iterative learning control and modified internal model control is proposed for improving the time waveform replication performance of electro-hydraulic shaking table. To reduce the modeling error between the estimated inverse model and the actual system, a modified internal model control strategy is first utilized to cope with the modeling error by back absorbing the nominal model and the inverse controller into a direct through block. Due to the non-minimum phase property of the nominal model estimated by the recursive extended least square algorithm, the zero magnitude error tracking controller is exploited to obtain a stable inverse controller. Then, an off-line iterative learning control strategy involving a real-time feedback controller is conducted on the compensated system to further enhance the replication performance. Therefore, the proposed algorithm combines the merits of modified internal model control and off-line iterative learning control and simplifies the conventional iterative control process by eliminating consecutive computation of Fourier and inverse Fourier transforms. The combined strategy is first programmed in MATLAB/Simulink and then compiled to a real-time personal computer with xPC target technology for implementation. Experiment results demonstrate that a better tracking accuracy and a faster convergence rate are achieved with the proposed algorithm than conventional pure iterative learning controller.
    Type of Medium: Online Resource
    ISSN: 0959-6518 , 2041-3041
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
    detail.hit.zdb_id: 2024903-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 7
    Online Resource
    Online Resource
    SAGE Publications ; 2020
    In:  Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering Vol. 234, No. 5 ( 2020-05), p. 622-633
    In: Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering, SAGE Publications, Vol. 234, No. 5 ( 2020-05), p. 622-633
    Abstract: In this article, the position control problem of electro-hydraulic servo systems with feedback signal transmission delay is studied. In order to improve the control accuracy of the system, a hybrid controller which combines a delay observer, a nonlinear disturbance observer and a backstepping controller is proposed. The controller has the characteristics of compensating the delay of signal transmission, restraining the uncertain disturbance of control systems and high control precision. In order to verify the stability and validity of the proposed hybrid controller, a single-degree-of-freedom electro-hydraulic shaking table is used to verify the experimental results. The experimental results show that the proposed controller has better control effects than proportional integral derivative and backstepping controller.
    Type of Medium: Online Resource
    ISSN: 0959-6518 , 2041-3041
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
    detail.hit.zdb_id: 2024903-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 8
    Online Resource
    Online Resource
    SAGE Publications ; 2018
    In:  Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit Vol. 232, No. 2 ( 2018-02), p. 369-383
    In: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, SAGE Publications, Vol. 232, No. 2 ( 2018-02), p. 369-383
    Abstract: Energy-efficient operation of trains in subway systems is regarded as one of the most effective strategies to cut down the operational cost. Most of the studies about the energy-efficient operation of trains aim to minimize the consumption of mechanical energy of trains. In this paper, an energy-efficient train control model is proposed under the practical billing system by introducing the traction efficiency. In addition, a numerical solution approach is presented to solve the energy-efficient driving strategy, which consists of the control sequences and the corresponding switching points. First, the authors analyze the energy-efficient control problem by applying the maximum principle, from which the energy-efficient control regime is proved to include the maximum acceleration, coasting, cruising with partial braking, and maximum braking. Second, the control sequences for one section are fully analyzed and an algorithm is presented to calculate the switching points with the energy consumption constraint. To obtain the solution to an interval with variable speed limits and gradients, the interval is divided into several sections, where the gradient and speed limit of each section are constants. A primary energy-efficient solution, which costs a longer trip time, is given. Then, energy units are assigned into multiple sections to shorten the trip time of the primary solution. Specifically, each energy unit is added into the selected section to achieve the maximum time reduction. Finally, the energy-efficient driving strategy at all sections will be obtained when the scheduled trip time of the interval is delivered. Some examples based on the practical data are conducted to illustrate that the proposed approach has a good potential on saving energy of trains.
    Type of Medium: Online Resource
    ISSN: 0954-4097 , 2041-3017
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
    detail.hit.zdb_id: 2024901-9
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 9
    Online Resource
    Online Resource
    SAGE Publications ; 2016
    In:  Journal of Vibration and Control Vol. 22, No. 19 ( 2016-11), p. 3945-3964
    In: Journal of Vibration and Control, SAGE Publications, Vol. 22, No. 19 ( 2016-11), p. 3945-3964
    Abstract: Shake tables are essential facilities in the laboratory for evaluating structural performance subject to vibration excitation. In this paper, to improve the time waveform replication accuracy of electro-hydraulic shake tables (EHSTs), an improved feedforward inverse control algorithm with adaptive refinement is proposed. The EHST system transfer function and stable inverse model is firstly estimated and designed by multi-step recursive extended least squares algorithm and zero magnitude error tracking controller technology, respectively. To reduce the side effect of model identification errors between the estimated and actual system, a system model corrector is further identified based on the previous estimated EHST model and an inverse corrector is obtained so as to constitute the improved feedforward inverse controller (iFIC) by cascading the inverse corrector to the previous designed inverse model. Then, an adaptive refinement controller using a least mean square algorithm is applied to the iFIC controlled system to cope with system uncertainties and nonlinear effects. Therefore, the proposed algorithm combines the merits of feedforward inverse control and adaptive control. Finally, with the help of xPC rapid prototyping technology, experiments are conducted on a real uniaxial EHST system and the experimental results demonstrate that the proposed algorithm exhibits a better tracking accuracy than the conventional controllers for shake tables.
    Type of Medium: Online Resource
    ISSN: 1077-5463 , 1741-2986
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2016
    detail.hit.zdb_id: 2070247-4
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 10
    Online Resource
    Online Resource
    SAGE Publications ; 2019
    In:  Technology in Cancer Research & Treatment Vol. 18 ( 2019-01-01), p. 153303381987077-
    In: Technology in Cancer Research & Treatment, SAGE Publications, Vol. 18 ( 2019-01-01), p. 153303381987077-
    Abstract: The newly released Protura 6 degrees-of-freedom couch (CIVCO) has limited quality assurance protocols and pertinent publications. Herein, we report our experiences of the Protura system acceptance, commissioning, and quality assurance. Methods: The Protura system integration was tested with peripheral equipment on the following items: couch movement range limit, 6 degrees-of-freedom movement accuracy, weight test and couch sagging, system connection with Linac, isocentricity of couch and rotation alignment, kV and cone-beam computed tomography imaging of HexaCHECK with MIMI phantom (Standard Imaging), and an in-house custom 6 degrees-of-freedom quality assurance phantom. A couch transmission measurement was also performed. Results: The vertical, longitudinal, and lateral ranges of the 6 degrees-of-freedom couch pedestal are 43.9 to 0.0 cm, 24.6 to 149.5 cm, −20.6 to 20.7 cm, respectively. The couch movement accuracy was within 1 mm in all directions. The couch sagging with a 200 lbs (∼91 kg) evenly distributed object is 1.0 cm and 0.4° pitch in the distal end of the couch. The isocentricity of the couch was about 0.5 mm in diameter of all crosshair projections on the couch isocenter level, and the largest couch rotation alignment observed was (0.3°) at the couch angle of 90°. The deviation from the reference position (zero position) of the HexaCHECK phantom, measured by matching the cone-beam computed tomography with the reference planning computed tomography, was found to be below 0.2 mm in the anterior–posterior and right–left dimensions, 0.4 mm in superior–inferior dimension, and 0.1° in roll, pitch, and yaw directions. Conclusions: A 6 degrees-of-freedom quality assurance phantom is helpful for the commissioning and routine quality assurance tests. Due to the third-party integration with Linac, the system is prone to “double-correction” errors. A rigorous quality assurance program is the key to a successful clinical implementation of the Protura system.
    Type of Medium: Online Resource
    ISSN: 1533-0346 , 1533-0338
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
    detail.hit.zdb_id: 2146365-7
    detail.hit.zdb_id: 2220436-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...