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Introduction: Arteriovenous fistula or arteriovenous graft is essential to long‐term survival and quality of life in patients receiving hemodialysis. To date, no research has examined the clinical impacts of different puncture methods. This study compared the rope ladder and area puncture techniques in terms of vascular patency, pain, and quality of life among patients receiving hemodialysis. Methods: A prospective longitudinal study was performed with 6‐month follow‐up. A total of 98 participants recruited from a hemodialysis center in Taiwan were randomly assigned to receive the rope ladder technique (experimental group) or the area puncture technique (control group). Vascular patency was assessed by examining access flow and percutaneous transluminal angioplasty rate. Pain and quality of life were measured using the Numerical Pain Rating Scale (NPRS) and Kidney Disease Quality of Life Instrument (KDQOL‐36™), respectively. All outcome variables were measured repeatedly and analyzed using a generalized estimating equation. Results: Overall, quality of life was significantly better for the experimental group than for the control group (β = 47.23, p < 0.001). The percutaneous transluminal angioplasty rate was lower for the experimental group than for the control group (12.0% vs. 18.8%). However, no significant differences were found in access flow and pain level between the two groups over time. Conclusion: Hemodialysis patients who received the rope ladder puncture technique had a lower percutaneous angioplasty rate and better quality of life than patients who received the area puncture technique, suggesting that the rope ladder technique could be implemented as a routine cannulation method in hemodialysis clinics. [ABSTRACT FROM AUTHOR]

External displacement control (EDC) is essential to a structural test in which a servo‐hydraulic actuator is connected to the specimen through loading fixtures, steel plates, and bolts in order to ensure that the specimen deformation meets the predefined displacement profile accurately. However, external displacement transducers for actuator feedback control could be detached from the specimen due to concrete spalling or steel buckling, leading to potential risks associated with actuator control stability and safety. In this study, image‐based displacement feedback control of actuators for structural testing is proposed and validated, which provides a noncontact approach to measure specimen deformation. In the proposed control scheme, a high‐speed camera is used to capture the images of a feature on the specimen during the test. The specimen deformation is calculated by using the captured images through online image processing and analysis. The actuator controller utilizes the calculated displacement as the feedback signal for displacement control. Finally, the proposed control scheme is validated in the laboratory. Two types of loading protocols are adopted for experimental validation including quasi‐static cyclic testing and dynamic loading testing. Experimental results demonstrate that the proposed image‐based displacement feedback control of the actuator completes quasi‐static cyclic tests and dynamic loading tests successfully and stably with satisfactory displacement tracking performance. The proposed method provides an alternative for EDC in a structural test. [ABSTRACT FROM AUTHOR]

Seismic responses of high-rise buildings are dominated by the first few vibration modes; therefore, high-floor responses contain long predominant vibration periods. However, it may not be achievable to investigate the seismic performance of nonstructural facilities at high levels of high-rise buildings in the laboratory by using seismic shake tables because of the actuator stroke limitation. In this study, an advanced control strategy that incorporates a transfer system with modern control algorithms is proposed for shake tables to replicate high-floor responses of high-rise buildings subjected to earthquakes. First, design diagrams are proposed to determine the parameters of the transfer system. Then, a set of friction pendulums is adopted as the transfer system for the proof-of-concept stage. A mathematical model for the set of friction pendulums is developed for numerical studies prior to real experimental validation. Three linear controllers and three nonlinear controllers are designed and synthesized to verify the feasibility and applicability of the proposed strategy. Finally, the friction pendulum set is installed on a uniaxial shake table to replicate the roof responses of a 34-story building subjected to historical earthquakes. Experimental results demonstrate the proposed control strategy successfully replicates floor responses of the high-rise building that cannot be achieved formerly. [ABSTRACT FROM AUTHOR]

Sloped rolling-type isolation devices incorporating built-in friction damping and pounding preventer have been verified to be effective for mitigation of seismic risks posed to critical equipment and facilities. Although the built-in damping design can effectively suppress excessive displacement responses, it also increases the acceleration transmitted to the protected object above the isolation device. In this study, a novel mechanism using embedded electromagnets is proposed to improve the control performance of the isolation device. By varying the input currents to the electromagnets, the corresponding magnetic force becomes controllable and can appropriately adjust the normal force applied to the sliding interface, leading to indirect semi-active control of friction damping force. The efficacy of the proposed mechanism is verified through several shaking table tests. Experimental results demonstrate that the control target of the isolation device can be semi-actively achieved using the electromagnetic mechanism. Accordingly, a numerical model of such a smart isolation system, the incorporation of the proposed controllable damping mechanism into the conventional sloped rolling-type isolation device, is proposed and calibrated by the experimental data. Its effectiveness and advantage can be clearly observed particularly when appropriate control algorithms are applied to calculating input currents for the electromagnets. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Real-time hybrid testing is a very effective technique for evaluating the dynamic responses of rate-dependent structural systems subjected to earthquake excitation. A smart base isolation system has been proposed by others using conventional low-damping isolators and controllable damping devices such as magnetorheological (MR) dampers to achieve specified control target performance. In this paper, real-time hybrid tests of a smart base isolation system are conducted. The simulation is for a base-isolated two-degrees-of-freedom building model where the superstructure and the low-damping base isolator are numerically simulated, and the MR damper is physically tested. The target displacement obtained from the step-by-step integration of the numerical substructure is imposed on the MR damper, which is driven by three different control algorithms in real-time. To compensate the actuator delay and improve the accuracy of the test, an adaptive phase-lead compensator is implemented. The accuracy of each test is investigated by using the root mean square error and the tracking indicator. Experimental results demonstrate that the hybrid testing procedure using the proposed actuator compensation techniques is effective for investigating the control performance of the MR damper in a smart base isolation system. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Real-time hybrid testing is an experimental technique for evaluating the dynamic responses of structural systems under seismic loading. Servo-hydraulic actuators, by nature, induce inevitable time delay between the command and the achieved displacements. This delay would lead to incorrect test results and even cause instability of the system; therefore, delay compensation is critical for stability and accuracy of hybrid simulations of structural dynamic response. In this paper, a dual delay compensation strategy is proposed by a combination of a phase lead compensator and a restoring force compensator. An outer-loop feed-forward phase lead compensator is derived by introducing the inverse model in the z domain. The adaptive law based on the gradient algorithm is used to estimate the system delay in the format of parametric model during the test. It is shown mathematically that the parameter in the delay estimator is guaranteed to converge. The restoring force compensator is adopted to improve the accuracy of experimental results especially when the structure is subjected to high frequency excitations. Finally, analytical simulations of an inelastic SDOF structure are conducted to investigate the feasibility of the proposed strategy. The accuracy of the dual compensation strategy is demonstrated through several shaking table tests. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Coupled steel plate shear wall (C-SPSW) consists of two or more steel plate shear walls interconnected by coupling beams at the floor levels. In this study, a six-story C-SPSW prototype building was designed. A 40% scale C-SPSW specimen, which is representative of the bottom two-and-half-story substructure of the prototype, was cyclically tested using Multi-Axial Testing System at the National Center for Research on Earthquake Engineering in 2009. In addition to a constant vertical force representing the gravity load effects, cyclic increasing displacements and the corresponding overturning moments transmitted from the upper stories were computed online and simultaneously applied on the substructural specimen. This paper firstly introduces the designs of the prototype C-SPSW and the test specimen. Then, the test results and the numerical simulation are discussed in detail. Test results confirm the effectiveness of the proposed column capacity design method, which aims at limiting the plastic hinge formation within the bottom quarter height of the bottom column. Test and analytical results suggest that the coupling beam rotational demands can be estimated as the design story drifts when the formation of desirable plastic mechanism of the C-SPSW is expected. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]