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This paper evaluates the influence of supporting frames on the seismic performance of an ultra-high voltage (UHV) gas insulated switchgear (GIS) bushing. Shaking table tests were carried out on a full-size UHV-GIS bushing mounted on two identical supporting frames except for their braces and joints. Finite element analyses were carried out on the joints' stiffness of the two frames, and seismic analyses on the bushing-supporting frame systems were conducted. Afterwards, parametric analyses on the joints' rotational and axial stiffness in the frames were carried out. The results indicated that the dynamic properties of the supporting frames affect the seismic performance of the bushing. After retrofitting, the amplification effects of the frame were reduced, and the seismic performance of the system improved. Moreover, the frame mainly amplified the acceleration response spectra near the fundamental frequency of the frame itself. The supplemented braces made greater contributions to reduce the seismic responses of the GIS bushiung, and increasing the joints' stiffness could reduce the severity of seismic responses on a bushing.

Since the seismic performance of the bypass switch (BPS) cannot satisfy the stress safety factor requirement, an isolated combination of wire ropes with linear viscous dampers was employed. The assembled base isolation was designed using modal parameters, and the effectiveness of the isolation was validated numerically using finite element (FE) analysis and experimentally by the shaking table test. The numerical study shows that wire rope isolation can reduce the stress of a BPS considerably. Furthermore, the implementation of supplementary viscous dampers can further reduce the stress and, more importantly, displacement response, which is significant for UHV equipment. The middle section of BPS generates obvious high frequency vibration during test, although the root section still experiences the maximum stress response. Besides, testing verified the reliability of the FE model and confirmed that the stress safety factor requirement was satisfied. Therefore, the isolation comprised of wire ropes and a viscous damper is proposed to improve the seismic performance of the slender 800 kV composite BPS.

A model of interconnected electrical equipment was established to study how flexible conductors affect the seismic responses of electrical equipment. The model was validated by conducting shaking table tests on an interconnected 220-kV full-size disconnecting switch-breaker system. The system was connected by flexible conductors of varying slackness. Afterwards, the model was adopted to carry out parametric analyses of the interconnected equipment. The tests and analyses showed that the critical sag-to-span ratio of a flexible conductor is related to equipment frequency and peak ground acceleration. Specifically, when the sag-to-span ratio of the conductor was less than the critical ratio, the horizontal terminal force increased rapidly. Even if the conductor was not straightened in the earthquakes considered, its vibration amplified the seismic responses of the interconnected equipment. Both the frequency ratio of the interconnected equipment and the frequency of the softer equipment influenced the interconnected effects of the electrical equipment. Furthermore, the displacement of the lower-frequency equipment made a larger contribution to the observed coupling effects.

Extreme winds may expose overhead transmission lines to loads that may result in the collapse of transmission towers leading to severe economic losses. This paper develops a modelling framework to assess the fragility of transmission towers under extreme winds such as tropical storms. To this end, the wind loading on a transmission tower is represented by a combination of three wind load components (i.e., the transverse and longitudinal tower loads as well as the wire load) expressed in terms of three key wind load-related input parameters (wind speed, wind angle of attack and horizontal span of the transmission line). The wind load-carrying capacity of towers is accordingly defined by a three-dimensional convex-curve surface with the three wind load components as the principle axes. A kriging surrogate model is established for the tower capacity surface as a function of uncertain structural parameters, based on the results from the nonlinear static analysis of the tower and Latin-hypercube sampling. Accordingly, the limit state function would suggest tower failure if the wind load effect exceeds the tower capacity defined by the surface. In this framework, the tower fragility is established by the Monte Carlo simulation. If the wind intensity, wind direction and line configuration are known, the wind load components can be evaluated. Utilizing the surrogate model, the capacity surfaces of sample towers are also obtained in terms of the simulated uncertain structural parameters simulated. Comparison between the estimated wind load components and the simulated sample surfaces yields the fragility curve. The proposed framework is demonstrated by a numerical example, as well as an application to a typhoon scenario analysis in which the failure probability of a real-world long-distance transmission line is assessed.

To evaluate the terminal force and configuration of bundled flexible conductors used in high voltage substations, this study developed a parametric method for modelling the large planar deflection of the flexible conductors. The flexible conductors were assumed to be planar beams. Based on the chained-beam constraint model (CBCM), the equations of the constraint effects of spacers and the geometric constraint of the bundled conductors were added to the model. Additionally, the CBCM was modified to capture the loading of a concentrated force on the intermediate part of the conductors. The model was validated by static tests and finite element analyses. Some case studies on the terminal force and configuration of the bundled flexible conductors based on this model were carried out. The terminal force and configuration of the bundled conductors calculated with and without bending stiffness were compared, showing that the constraint effects of the spacers increased the stiffness of the bundled conductors. Ignoring the bending stiffness and the constraint effects of the spacers will lead to analytical errors in the terminal force and configurations of the bundled flexible conductors used in high voltage substations.

To evaluate and improve the seismic performance of a ±800 kV ultra-high voltage (UHV) wall bushing-valve hall system, a finite element model of the system was established. Sixteen different earthquake ground motions were adopted in the analysis, and the critical seismic responses of the system were obtained. Moreover, a vibration theoretical model of the UHV wall bushing-valve hall system was established, and an investigation was conducted on the influence of different vibration components on the wall bushing seismic responses. The results indicate that the valve hall has an amplification effect on the seismic responses of the wall bushing and the vibration of the gable wall has a remarkable influence on the responses of the wall bushing. Two retrofitting measures were carried out on the valve hall to reduce the seismic responses of the wall bushing. It is concluded that increasing the stiffness of the gable wall could improve the seismic performance of the UHV wall bushing-valve hall system.

Overconsolidated (OC) clay has a strong dilatancy property, which has a significant effect on ultimate strength and deformation. Compared with normal consolidated (NC) clay, OC clay tends ...

Tuned mass dampers (TMD) are installed in base-isolated building to suppress the excessive isolator displacement and acceleration responses of primary structure. By incorporating an inerter element into the original configuration, the seismic performance of TMD is significantly enhanced. In this work, optimal solutions of tuned mass damper inerter (TMDI) for improving the seismic resilience of base-isolated building are proposed. The analytical formulations of optimal design of TMDI are respectively developed to minimize the H2 norm of the displacement of primary structure relative to the base floor and the isolator displacement. The performance of presented optimal methods are validated by using stationary responses under the stochastic excitations. Additionally, the seismic performance of TMDI with parameters obtained from the proposed method are compared with the established methods.

This paper presents a capacitive displacement sensor based on a capacitively fed inverted-F antenna (CFIFA) for displacement detection. The sensor is composed of a grounded L-shape patch and a rectangular upper patch, forming a capacitor between them. The asymmetric dipole model is adopted to explain the frequency shift and current distribution of the proposed antenna sensor at its first-order resonance. The numerical simulation of the CFIFA using the Ansoft high-frequency structure simulator (HFSS) software is carried out to optimize the dimensional parameters, allowing the antenna to perform better. Two sets of CFIFAs are fabricated and tested for verification. Results show that the CFIFA has a good linear relationship between its first resonant frequency and the relative displacement, and is capable of a long range of displacement measuring.

This paper presents a passive wireless long-range displacement sensor that is based on the circular patch antenna, and the detecting range of the sensor can be customized. The sensor consists of a chipped circular antenna with two opened rectangular windows, a substrate, and a ground plate with a sloping channel. No bonding between the antenna and the ground plate allows for the chipped antenna to slide along the sloping channel. The channel will drive the current flow on the plate once the chip is activated, increasing the effective electrical length and, consequently, decreasing the resonant frequency of the circular antenna. The sensing mechanism equates the measuring displacement to the relative movement of the antenna with respect to the ground that achieves the measurement of long-range displacement and, thus, the proposed sensor can avoid stress damage to the antenna due to excessive deformation. Three different range sensors were simulated in the the Ansoft high frequency structure simulator (HFSS). The results show that the resonance frequency of the antenna has a linear relationship with the varying chute depth beneath the chip. Three sensors were fabricated, and the experimental results also validated that the sensitivity of the sensor can be adjusted.

Inerter-based vibration control systems have been developed rapidly in recent years. However, previous studies mainly focus on the development of new devices and parameter optimization strategies, while ignoring the improvements in the utilization efficiency of the inerter system that the bracing system and novel installation methods may bring. In this paper, a cross-layer installed cable-bracing inerter system (CICBIS) is proposed to improve the utilization efficiency of the inerter system, which can cross more layers and is suitable for shear-type multi-degree-of-freedom (MDOF) structures. A demand-based cable-bracing inerter system (CBIS) design method is developed. The mass enhancement and utilization efficiency improvement of the inerter system caused by the cross-layer installation are quantified through calculating the effective inerter-mass ratio of the CBIS-equipped MDOF structure. A 10-story benchmark structure is used to verify the control performance of the CICBIS and the design method. The analysis results show that the proposed design method can exert the cable-bracing system&rsquo, s adjustability and the damping enhancement of the inerter system. The CICBIS can reduce the total apparent mass and damping coefficient requirements of the inerter systems without increasing the control force. It means that the proposed design method is effective, and the CICBIS has a high efficiency.

Based on the classical Timoshenko beam theory, the rotary inertia caused by shear deformation is further considered and then the equation of motion of the Timoshenko beam theory is modified. The dynamic characteristics of this new model, named the modified Timoshenko beam, have been discussed, and the distortion of natural frequencies of Timoshenko beam is improved, especially at high-frequency bands. The effects of different cross-sectional types on natural frequencies of the modified Timoshenko beam are studied, and corresponding simulations have been conducted. The results demonstrate that the modified Timoshenko beam can successfully be applied to all beams of three given cross sections, i.e., rectangular, rectangular hollow, and circular cross sections, subjected to different boundary conditions. The consequence verifies the validity and necessity of the modification.

Background As an important member of platinum-based chemotherapeutic drugs, cisplatin is effective and is commonly used in the treatment of esophageal cancer. However, repeated use of cisplatin usually causes severe side-effects on patients. Novel approaches should be explored to increase the sensitivity of cancer cells to cisplatin. Methods The expression level of miR-183 in esophageal cancer tissues and cell lines was measured by quantitative reverse transcriptase real-time PCR (qRT-PCR). The sensitivity of EC cell lines to cisplatin was evaluated by CCK-8 assay and flow cytometry. Luciferase reporter assay was used to confirm the association between miR-183 and FOXO1. The apoptosis pathway of EC cells was tested by Western blot assay. Results The expression level of miR-183 was increased in esophageal cancer patients’ tumor tissues and esophageal cancer cell lines. However, knockdown of miR-183 was found to enhance the effect of cisplatin on inducing the apoptotic cell death of esophageal cancer cells. In the mechanism research, we proved that FOXO1 was the target of miR-183 in esophageal cancer cells. Inhibition of miR-183 increased the expression of FOXO1 to promote the expression of Bim and Noxa. As Bim and Noxa acted as key pro-apoptotic proteins in mitochondrial apoptosis, inhibition of miR-183 enhanced the cisplatin-induced apoptosis pathway in esophageal cancer. Conclusion Knockdown of miR-183 enhanced the cisplatin-induced apoptosis in esophageal cancer through an increase of FOXO1 expression.

Wind turbine tower vibration parameters are critical for design and maintenance of wind farms. In this paper, measurement campaigns of two in-service 65-m tall wind turbine towers are inves...

This paper presents an angle sensor based on a sector ring patch antenna (SRPA) for loose bolt detection. The sensor is comprised of two parts, a ring substrate sandwiched between a ground plane and a sector ring radiation patch, and a sector ring substrate covered by a radiation patch. The two radiation patches are partially overlapped and the overlapped areas are in contact allowing the electric current to flow within the combined radiation patch. The resonant cavity theory is adopted to explain the relationship between the frequency shift and the overlapped angle. The Ansoft high frequency structure simulator software is used to simulate SRPA, and the dimensional parameters of the antenna are optimized to make the antenna perform better. For verification, two sets of SRPAs are fabricated and tested.

Purpose This paper aims to develop a comprehensive uncertainty quantification method using evidence theory for Park–Ang damage index-based performance design in which epistemic uncertainties are considered. Various sources of uncertainty emanating from the database of the cyclic test results of RC members provided by the Pacific Earthquake Engineering Research Center are taken into account. Design/methodology/approach In this paper, an uncertainty quantification methodology based on evidence theory is presented for the whole process of performance-based seismic design (PBSD), while considering uncertainty in the Park–Ang damage model. To alleviate the burden of high computational cost in propagating uncertainty, the differential evolution interval optimization strategy is used for efficiently finding the propagated belief structure throughout the whole design process. Findings The investigation results of this paper demonstrate that the uncertainty rooted in Park–Ang damage model have a significant influence on PBSD design and evaluation. It might be worth noting that the epistemic uncertainty present in the Park–Ang damage model needs to be considered to avoid underestimating the true uncertainty. Originality/value This paper presents an evidence theory-based uncertainty quantification framework for the whole process of PBSD.

It is of great importance to consider uncertainty due to insufficient data or imprecise information in topology optimization design. In this paper, evidence theory is presented to handle the imprecise data situation. The plausibility measure based on evidence theory is introduced to overcome the difficulty of constructing the precise probabilistic constraint. Furthermore, the topology problem in this evidence-based optimization design is solved by combined strategy of the differential evolution and superior topology technique. In order to overcome the difficulty of intensive computational cost in calculating plausibility measure, an improved method of evolutionary optimization design integrating with imprecise extremum idea is proposed. Two truss examples are given to demonstrate the proposed approach. The research indicates that deterministic results may be the failure solutions under epistemic uncertainty. Although evidence-based optimum topology designs are more conservative than deterministic results in aspects of weight and optimal structural topology layout, it gains a more robust design under epistemic uncertainty.

With the rapid development of subway systems, the negative environmental impacts of vibration induced by subways has gradually become a research hotspot. For the purpose of developing predictive models of vibration and designing effective vibration mitigation systems, continuous field dynamic measurements were conducted simultaneously in a subway tunnel, ground, and building in eastern China, the most prosperous region in China. The characteristics of vibration transmission and attenuation induced by subway were analyzed by statistical analysis of large amounts of measurement data. The results showed that most prominent and visible attenuation of vibration is from the track to the ballast bed in the tunnel, where the ground-borne vibration would quickly decrease exponentially with distance. The results also showed that the measured attenuation value of indoor vibration was approximate 0.76 dB on average between each floor. Moreover, the decay ratio of the vibration increased with the increase in the frequency range. Based on these findings, construction gauge of 20&ndash, 25 m outside of the tunnel is recommended. In addition, reducing the vibration source excitation intensity is the most effective vibration isolation method, especially by track structural transformation.

Evidence theory, with its powerful features for uncertainty analysis, provides an alternative to probability theory for representing epistemic uncertainty, which is an uncertainty in a system caused by the impreciseness of data or knowledge that can be conveniently addressed. However, this theory is time-consuming for most applications because of its discrete property. This article describes an adaptive sub-interval perturbation-based computational strategy for representing epistemic uncertainty in structural dynamic analysis with evidence theory. The possibility of adopting evidence theory as a general tool for uncertainty quantification in structural transient response under stochastic excitation is investigated using an algorithm that can alleviate computational difficulties. Simulation results indicate that the effectiveness of the presented strategy can be used to propagate uncertainty representations based on evidence theory in structural dynamics.

A new fracture criterion based on the crack opening displacement for peridynamic (PD) and dual-horizon peridynamics (DH-PD) is proposed. When the relative deformation of the PD bond between the particles reaches the critical crack tip opening displacement of the fracture mechanics, we assume that the bond force vanishes. A new damage rule similar to the local damage rule in conventional PD is introduced to simulate fracture. The new formulation is developed for a linear elastic solid though the extension to nonlinear materials is straightforward. The performance of the new fracture criterion is demonstrated by four examples, i.e. a bilateral crack problem, double parallel crack, monoclinic crack and the double inclined crack. The results are compared to experimental data and the results obtained by other computational methods.

A wind tunnel test on the aero-elastic model of UHV transmission tower line system was carried out for researching tower line system's dynamic behavior under different wind speeds. The effect of wires' vibration on tower was particularly addressed in the paper. For comparison, the single tower model and tower line system model were involved. Both alongwind and crosswind responses of tower were investigated. The wire's dynamic strain was traced synchronously for exploring the coupling vibration effect of tower line system. Comparing the responses of the single tower model and the tower line model, it is found that 70–90% displacement and strain are induced by wires. This action is more prominent in the alongwind direction. However, the peak response values of the tower line model are smaller than those of the single tower model. Test results in frequency domain indicate that the dynamic behavior of the tower becomes more susceptible to wind speed when it connects with wires. As to the tower line system, the response power spectra of the tower and the conductors show the tendency of moving to lower and higher frequency region respectively with the crests weakened and vibration energy dispersed when wind speed increases.

In the field of bridge health monitoring, it is ubiquitous to model the relationship for monitoring data. However, in many cases, especially for concrete bridge structures, field response data collected from sensors, such as strains and deflections, presents hysteresis phenomena due to the cyclic temperature variation. Such phenomena refer to the time-lag effect of the structure and impede the following correlation analysis because it will weaken the linearity among strains. In conventional methods, correlation analysis will be conducted after eliminating time-lag effect by using averaging method or simple phase shifting. In this paper, correlations between temperature-induced strain responses are investigated after the time-lag effect is accurately quantified by nonlinear phase shifting. In order to capture the features of nonlinear phase variation between responses, a novel approach, namely functional data analysis (FDA), is then proposed. Phase component is extracted through warping functions in square-root slope framework (SRSF) under Bayesian inference, in which the warping functions reveal the time delay effect between quasi-static strain data. The deformation pattern of warping function is further studied through functional principal component analysis (FPCA) in tangent space. After the phase difference is eliminated by the warping function, inter-relationship between strain data exhibits highly strong linearity instead of original hysteresis loop. To seek the underlying features of time-lag effect, hundreds of pairs of daily field measurements acquired from different locations on a long-span bridge have been analyzed to disclose statistical regularities. It is found that after the application of warping function, the time-lag effect has been remarkably eliminated and strong linearity of the responses emerges.

Peridynamics (PD) is a nonlocal continuum theory based on integro-differential equations without spatial derivatives. The fracture criterion is implicitly incorporated in the PD theory and fracture is a natural outcome of the simulation. However, capturing of complex mixed-mode crack patterns has been proven to be difficult with PD. On the other hand, the extended finite element method (XFEM) is one of the most popular methods for fracture which allows crack propagation with minimal remeshing. It requires a fracture criterion which is independent of the underlying discretization though a certain refinement is needed in order to obtain suitable results. This article presents a comparative study between XFEM and PD. Therefore, two examples are studied. The first example is crack propagation in a double notched specimen under uniaxial tension with different crack spacings in loading direction. The second example is the specimens with two center cracks. The results show that PD as well as XFEM are well suited to capture this type of behaviour.

Uncertainties originate from physical variability, data uncertainty, and modeling errors in the fatigue crack growth prediction analysis. This study presents an evidential uncertainty quantification (UQ) approach for determining uncertainties involved in revealing the material constants of the metal fatigue crack growth model with imprecise uncertainty information (i.e., epistemic uncertainty). The parameters in fatigue crack growth model are obtained by fitting the available sparse experimental data, and then the uncertainties in these parameters are considered. To alleviate the computational difficulties in the UQ analysis based on evidence theory, an interval optimization method based on differential evolution is used in finding the propagated belief structure. The overall procedure is demonstrated using the results of several replicated experiments on aluminum alloy CCT specimens.

Structures get local damaged during their daily service or natural disaster like earthquakes and hurricanes. Local damage will gradually develop and grow, which will lead to the overall damage of the structure, and even lead to the collapse. Therefore, local damage detection plays an important role in ensuring structural safety and lifecycle maintenance of structures. In response to this phenomenon, the paper propose a new local damage detection method based on spatial-temporal correlation in dense sensor networks without the need for exact knowledge of structural properties. Firstly, the structural response is collected by sensor networks. The collected response is then used to analyze spatial-temporal correlation between the responses of different points. The damage indicator in the paper is called the angle coefficient, which measures the angle between regressed plans from two different states of the system. To ensure accurate detection of local damage, coefficient of determination is used in the paper to evaluate the reliability of angle coefficient, and chooses angle coefficients with higher coefficient of determination to detect structural damage. The performance of proposed method was verified through a dynamic excitation experiment on a scaled model of twostory assembled frame structure. The frame structure was constructed at the State Key Laboratory for Disaster Reduction in Civil Engineering at Tongji University. There are 7 cases in the experiment, including three different damage degrees. According to the structural response collected from the experiment, the angle coefficient is calculated to detect local damage in the system. The results show that the proposed method can successfully detect local damage and its location in the structure, even at a complex environment. Comparing influence coefficients of different damage degrees, it can be found that there is a certain positive correlation between angle coefficient and damage degree of the structure. That is, the greater the damage degree is, the higher the angle coefficient is.

In this study, a novel vibration mitigation device which uses a displacement amplification mechanism is proposed. It is called cable-bracing inerter system (CBIS) and provides the additional damping force through inerter element, friction element and eddy current damping element. Eddy current damping is a non-contacting damping mechanism, and the damping ratio can be easily adjusted by varying the air gap between the permanent magnets and the conductor in this device. In the traditional tuned mass dampers, large additional mass is often required for its seismic control which is a limitation of a tuned mass damper. This device overcomes this kind of limitation and its effective masses can be several times than the actual mass. In this paper, we present a comprehensive study that involves experimental, analytical, and computational approaches. First, we described the principle of the CBIS which includes eddy current damping mechanism and an apparent mass amplifier using inerter. CBIS utilizes two cables which are easy to install to transmit control forces and deformation between the main structure and CBIS. Second, the theoretical model was given and to simplify the theoretical model of CBIS, the flexibility of the cable was neglected and the motion governing equation was also given. A series of free vibration tests and shaking table tests were conducted on a single degree of freedom (SDOF) steel-frame model with/without a CBIS to evaluate the effectiveness and performance of the CBIS in suppressing the vibration of the model. In the free vibration tests, the extend Kalman filter is used to identify the parameters of structure and CBIS. The results show that by using a properly designed inerter system, a lightly damped primary system can achieve a considerable reduction in its response with a small weight penalty. The experimental results show that the CBIS can effectively reduce the displacement and acceleration responses under different earthquake excitations.

The uncertainty in parameter estimation arises from structural systems&rsquo, input and output measured errors and from structural model errors. An experimental verification of the shuffled complex evolution metropolis algorithm (SCEM-UA) for identifying the optimal parameters of structural systems and estimating their uncertainty is presented. First, the estimation framework is theoretically developed. The SCEM-UA algorithm is employed to search through feasible parameters&rsquo, space and to infer the posterior distribution of the parameters automatically. The resulting posterior parameter distribution then provides the most likely estimation of parameter sets that produces the best model performance. The algorithm is subsequently validated through both numerical simulation and shaking table experiment for estimating the parameters of structural systems considering the uncertainty of available information. Finally, the proposed algorithm is extended to identify the uncertain physical parameters of a nonlinear structural system with a particle mass tuned damper (PTMD). The results demonstrate that the proposed algorithm can effectively estimate parameters with uncertainty for nonlinear structural systems, and it has a stronger anti-noise capability. Notably, the SCEM-UA method not only shows better global optimization capability compared with other heuristic optimization methods, but it also has the ability to simultaneously estimate the uncertainties associated with the posterior distributions of the structural parameters within a single optimization run.

BACKGROUND: To investigate the expression and significance of c-kit and epithelial-mesenchymal transition (EMT) molecules (E-cadherin, N-cadherin, Twist, Snail) in thymic epithelial tumors (TETs). METHODS: The tissue microarray technology and immunohistochemistry MaxVisionTM-use kit were used to detect the expression of c-kit and EMT molecular markers in 150 cases of paraffin sections of TET tissue and analysis the correlation between c-kit and EMT molecules and explore the malignancy and the relationship of clinicopathological parameters between c-kit, EMT molecules and TETs. RESULTS: The expression difference of c-kit and EMT molecular markers (E-cadherin, N-cadherin, Snail, Twist) in TETs subtypes was statistically significant (P

Monolithic patch antennas for deformation measurements are designed to be stressed. To avoid the issues of incomplete strain transfer ratio and insufficient bonding strength of stressed antennas, this paper presents a passive wireless crack sensor based on an unstressed patch antenna. The rectangular radiation patch of the proposed sensor is partially covered by a radiation sub-patch, and the overlapped length between them will induce the resonate frequency shift representing the crack width. First, the cavity model theory is adopted to show how the resonant frequencies of the crack sensor are related to the overlapped length between the patch antenna and the sub-patch. This phenomenon is further verified by numerical simulation using the Ansoft high-frequency structure simulator (HFSS), and results show a sensitivity of 120.24 MHz/mm on average within an effective measuring range of 1.5 mm. One prototype of proposed sensor was fabricated. The experiments validated that the resonant frequency shifts are linearly proportional to the applied crack width, and the resolution is suitable for crack width measuring.

This paper presents a passive displacement sensor based on a normal mode helical antenna. The sensor consists of an external helical antenna and an inserting dielectric rod. First, the perturbation theory is adopted to demonstrate that both the electric intensity and magnetic intensity have a noticeable gradient change within the in-and-out entrance of the helical antenna, which will cause the sensor to experience a resonant frequency shift. This phenomenon was further verified by numerical simulation using the Ansoft high frequency structure simulator (HFSS), and results show the linear correlation between the retrieved resonant frequency and the displacement. Two sets of proposed sensors were fabricated. The experiments validated that the resonant frequency shifts are linearly proportional to the applied displacement, and the sensing range can be adjusted to accommodate the user&rsquo, s needs.

In this paper, the concept of separated Inverted-F antenna (SIFA) is proposed, coupling feeding is used in SIFA, and the thickness of the additional capacitor’s dielectric is studied to find the suitable range of being a displacement sensor. Simulation result shows that the current can get through the capacitor, and feeder’s moving can let the resonant frequency shift linearly. So it’s reliable to transform the SIFA to a displacement sensor, so as to provide evaluation basis for structural health monitoring (SHM).

Since physical parameters are much more sensitive than modal parameters, structural parameter identification with an extended Kalman filter (EKF) has received extensive attention in structural health monitoring for civil engineering structures. In this paper, EKF-based parameter identification technique is studied with numerical and experimental approaches. A four-degree-of-freedom (4-DOF) system is simulated and analyzed as an example. Different integration methods are examined and their influence to the final identification results of the structural stiffness and damping is also studied. Furthermore, the effect of different kinds of noise is studied as well. Identification results show that the convergence speed and estimation accuracy under Gaussian noises are better than those under non-Gaussian noises. Finally, experiments with a five-story steel frame are conducted to verify the damage identification capacity of the EKF. The results show that stiffness with different damage degrees can be identified effectively, which indicates that the EKF is capable of being applied for damage identification and health monitoring for civil engineering structures.

The industrial chimney is one of the important components used in industrial processes. The tuned mass damper was introduced in previous studies to improve its reliability for resisting earthquakes. However, a large additional mass is generally required for applying a tuned mass damper in a chimney, which may be inappropriate owing to the additional moment action. In this study, the tuned mass inerter system (TMIS) is adopted as an ungrounded lightweight passive control device for the seismic response mitigation of high-rise chimneys. The ungrounded TMIS consists of a tuned mass element and a parallel-connected tuning spring and inerter subsystem. Considering that the influence of high modes on the responses of a high-rise chimney may not be neglected, distributed TMISs (d-TMISs) are proposed for installation on the chimney for multimode control of seismic response. A strategy to optimize d-TMISs for multimode control of high-rise chimneys is developed. A typical numerical chimney model is established to illustrate the proposed optimal design method. Time history analysis and comparative studies are conducted to verify the optimal multimode control design and the lightweight effect of d-TMISs compared to the traditional tuned mass dampers. The results show that by applying the proposed optimization in d-TMISs, the performance objectives can be achieved and the chimney’s responses involving the high-order modes can be reduced as anticipated. The required weight of d-TMISs is less than that for tuned mass dampers under an identical performance objective. It is observed that the proposed optimal multimode control method is effective and that d-TMISs can achieve the lightweight effect.

The damping estimation of an eight-story steel building equipped with oil dampers is examined, carried out by adopting a proposed framework, which consists of an enhanced strain-energy method and an improved direct method for model updating. The building is located at Tohoku Institute of Technology and is equipped with a structural monitoring system that measures its seismic response, including floor acceleration and displacement and force of oil dampers. The enhanced strain-energy method is first developed and employed to assess the supplemental damping and stiffness provided by oil dampers, herein quantified in the form of equivalent damping ratios and natural frequencies. Then, modal characteristics extracted from the earthquake measurements are modified accordingly and utilized for the building model updating, in which mass and stiffness matrices are corrected by the improved direct method. The updated model accurately reproduces the target modal data, especially measured mode participation factors, and is further used for the building response predictions. Through prediction validations, the precision of the modified modal parameters is verified. Finally, a large earthquake event is chosen to demonstrate the effectiveness of the proposed framework for the damping estimation of the investigated building.

In this paper, an adaptive immune clone selection algorithm for multi-objective optimization (AICSAMO) is proposed. A novel adaptive polynomial mutation operator with dynamic mutation probability i...

A robust multi-objective optimization method for truss optimum design is presented. In the robust design, materials and loads are assumed to be affected by epistemic uncertainties (imprecise or lack of knowledge). Uncertainty quantification using evidence theory in optimum design subject to epistemic uncertainty is undertaken. In addition to a functional objective, an evidence-based plausibility measure of failure of constraint satisfaction is minimized to formulate the robust design into a multi-objective optimization problem. In order to alleviate the computational difficulties in the evidence theory-based uncertainty quantification analysis, a combined strategy of differential evolution-based interval optimization method and parallel computing technique is proposed. A population-based multi-objective differential evolution optimization algorithm is designed for searching robust Pareto front. Two truss structures with shape and sizing optimum design problems are presented to demonstrate the effectiveness and applicability of the proposed method.

In this paper, the full rehabilitation process of a damaged passively controlled building is reported. A hybrid retrofit plan that uses tin-rubber bearings to replace the damaged oil dampers is pro...

Due to the increased service life, environmental corrosion, unreasonable construction, and other issues, local defects inevitably exist in civil structures, which affect the structural performance and can lead to structural failure. However, research on grout defect identification of precast reinforced concrete frame structures with rebars spliced by sleeves faces great challenges owing to the complexity of the problem. This study presents a multiple-variable spatiotemporal regression model algorithm to identify local defects based on structural vibration responses collected using a sensor network. First, numerical simulations were carried out on precast beam&ndash, column connection models by comparing the identification results based on a single-variable regression model, two-variable spatial regression model, and two-variable spatiotemporal regression model, furthermore, a multiple-variable spatiotemporal regression model was proposed and robustness analysis of the damage indicator was carried out. Then, to explore the validity of the proposed method, a nondestructive vibration experiment was considered on a half-scaled, two-floor, precast concrete frame structure with column rebars spliced by defective grout sleeves. The results show that local defects were successfully identified based on a multiple-variable spatiotemporal regression model.

Due to the uncertainties originating from the underlying physical model, material properties and the measurement data in fatigue crack growth (FCG) processing, the prediction of fatigue crack growth lifetime is still challenging. The objective of this paper was to investigate a methodology for uncertainty quantification in FCG analysis and probabilistic remaining useful life prediction. A small-timescale growth model for the fracture mechanics-based analysis and predicting crack-growth lifetime is studied. A stochastic collocation method is used to alleviate the computational difficulties in the uncertainty quantification in the small-timescale model-based FCG analysis, which is derived from tensor products based on the solution of deterministic FCG problems on sparse grids of collocation point sets in random space. The proposed method is applied to the prediction of fatigue crack growth lifetime of Al7075-T6 alloy plates and verified by fatigue crack-growth experiments. The results show that the proposed method has the advantage of computational efficiency in uncertainty quantification of remaining life prediction of FCG.

Circular RNAs (circRNAs) are a type of endogenous non-coding RNA with multiple binding sites that specifically bind to microRNAs (miRNAs) and serve an important role in cellular regulatory networks. Patients exhibit varying levels of lymphatic metastasis in a clinical setting. The present study investigated the association between circRNAs and lymphatic metastasis in esophageal squamous cell carcinoma (ESCC). The tissue samples were divided into three groups, including early tumor stage associated with advanced nodal stage (T1 group), advanced tumor stage associated with early nodal stage (T2 group) and healthy esophageal epithelial tissues as the control group (C group). Gene chip analysis identified circRNAs, and those with possible regulatory functions were validated by reverse transcription-quantitative polymerase chain reaction analysis (RT-qPCR). circRNAs containing miRNA response element (MRE) sequences were obtained, and circRNA/miRNA prediction software was used to predict miRNAs that may interact with circRNA. A total of 12,275 circRNAs were detected, including 861 with statistically significant differences. A comparison between the T1 and C groups identified 152 upregulated circRNAs and 431 downregulated ones, while a comparison between the T2 and C groups identified 187 upregulated and 481 downregulated circRNAs. A T1/T2 group comparison revealed that four circRNAs were upregulated and seven were downregulated (fold change >1.5; P