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Uncertainty Quantification and Model Calibration
The damage-based structural seismic performance evaluations are widely used in seismic design and risk evaluation of civil facilities. Due to the large uncertainties rooted in this procedure, the application of damage quantification results is still a challenge for researchers and engineers. Uncertainties in damage assessment procedure are important consideration in performance evaluation and design of structures against earthquakes. Due to lack of knowledge or incomplete, inaccurate, uncleardoi:10.5772/intechopen.68153 fatcat:57kziqljircqpfpitmng7ihagi
more »... formation in the modeling, simulation, and design, there are limitations in using only one framework (probability theory) to quantify uncertainty in a system because of the impreciseness of data or knowledge. In this work, a methodology based on the evidence theory is presented for quantifying the epistemic uncertainty of damage assessment procedure. The proposed methodology is applied to seismic damage assessment procedure while considering various sources of uncertainty emanating from experimental force-displacement data of reinforced concrete column. In order to alleviate the computational difficulties in the evidence theory-based uncertainty quantification analysis (UQ), a differential evolutionbased computational strategy for efficient calculation of the propagated belief structure in a system with evidence theory is presented here. Finally, a seismic damage assessment example is investigated to demonstrate the effectiveness of the proposed method.
The thermohydrodynamic lubrication properties of overturning slipper pair considering elastic deformation and thermal deformation are studied. The effect of thermal deformation and elastic deformation of slipper surface on the thermoehydrodynamic lubrication of slipper pair under work conditions of different load pressure, shaft speed and inlet temperature is discussed mainly. The lubrication properties of slipper pair is analyzed by using Reynolds equation and film thickness equation baseddoi:10.3901/jme.2017.04.168 fatcat:updqe3xdffdovic3vsnvcuu2jy
more »... te difference method. The slipper deformation is calculated by finite element method. The film temperature distribution is calculated by energy equation and heat conduction equation. The results show that there is a convex shape of oil film temperature and pressure distribution in slipper pocket and edge. Oil film temperature cross slipper radius decreases from the slipper pocket to the edge of slipper. The high shaft speed, load pressure and inlet temperature are, the more obvious damped oscillation of oil thickness will be. The fiction torque increases with decreasing oil film thickness. The peaks of fiction torque and oil film thickness exist at the high-pressure and low-pressure alternate region of piston pump.
Tang et al. (2020) presented an overview of recognition and localization methods for vision-based fruitpicking robots. ... Tang et al. (2019) presented a dynamic real-time detection method for examining surface deformation and full-field strain in recycled aggregate concrete-filled steel tubular columns. ... Copyright © 2020 Tang, Xie, Zhao and Xue. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). ...doi:10.3389/fmats.2020.00298 fatcat:w6hg6njtdbbfzmiykq5zcbzi6q
et al. (2007); Tang and Xue(2008)). ... Kalman filter (Yang et al. (2005) ), the H ∞ filter method (Sato and Qi (1998) ), and the particle filter method (Li et al. (2004) ; Tang and Sato (2005) ). ...doi:10.3130/jaabe.8.517 fatcat:4dfl6ohxe5f7tfackvx5ovq3la
In this paper, cables are proposed to connect the inerter and main frame for translation-to-rotation conversion, i.e., the cable-bracing inerter system (CBIS), with a magnified mass and enhanced damping effect. This novel configuration has the benefits of deformation relaxation at the connecting joints, easy installation, and an adaptive layout for nonconsecutive-story deployment. Dynamic motion equations were established for a single degree-of-freedom (SDOF) model equipped with a CBIS. Thedoi:10.3390/app9194096 fatcat:3v7mqyoosffgvmntgbjkguwjam
more »... uence of dimensionless parameters, such as inertance-mass ratio, stiffness ratio and additional damping ratio on vibration mitigation were studied in terms of displacement response and force output. A single objective and multiple objective optimal design method were developed for a CBIS-equipped structure based on a performance-oriented design framework. Finally, the mitigation effect was illustrated and verified by a numerical simulation in a time-domain. The results showed that a CBIS is an effective structural response mitigation device used to mitigate the response of structural systems under earthquake excitation. Using the proposed optimization method, CBIS parameters can be effectively designed to satisfy the target vibration control level.
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 lifetimedoi:10.3390/met10050646 fatcat:bdsb5rqt7vfgzfsol7eaakrak4
more »... 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.
The heat exchanger is widely applied to many axial piston machines, and its structure significantly affects the heat transfer performance. Flow characteristic and heat transfer performance in heat exchanger channels with different dimples geometries are numerically and experimentally analyzed in this research work. The objective is to present details of flow field structure and heat transfer mechanisms for the dimpled channel. The realizable k-ε turbulence model was employed in the numericaldoi:10.3390/machines9040072 fatcat:r6svspse4jctjh4gt23zqqgtey
more »... ulations with the Re range from 3500 to 20,000. The temperature contour, local streamlines, friction factor, and Nu were presented to illustrate the heat transfer enhancement mechanisms. From this investigation, it is found that dimples cause downward flow, improve the flow mixing and reattachment, interrupt the boundary layer and form periodic impingement flows and then greatly improve the heat transfer. The heat transfer coefficient of hemispherical dimple channels with the three kinds of dimple radius–depth ratios is the highest, and it is about 27.2% higher than that of the traditional rhombus dimple channel. Comparing to the rhombus dimpled channel, the lower flow friction performance of the hemispherical dimple channel depends on the lower dimple radius–depth ratio. The hemispherical dimpled channel present better overall thermal performance due to the strength and extent of the recirculation flow reduction.
There are two main approaches to solving this problem: sampling (Walpole 1998 ) and optimization (Storn & Price 1997; Tang et al 2008) . ...doi:10.1007/s12046-015-0388-0 fatcat:hovatbfp6zg5xidttjdehpzxry
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 theirdoi:10.3390/app8122480 fatcat:bdmhuekfdvht3huq4awapj7544
more »... nce 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 Sox family member Sox30 is highly expressed in the testis of several vertebrate species and has been shown to play key roles in spermiogenesis. However, its transcription regulation remains unclear. Here, we analyzed the Sox30 promoter from the teleost fish Nile tilapia (Oreochromis niloticus) and predicted a putative cis-regulatory element (CRE) for doublesex and mab-3 related transcription factor 1 (Dmrt1), a male-specific transcription factor involved in male sex differentiation.doi:10.3390/ijms20215487 fatcat:qkrv4yzzefhs3nhmjqcuuallum
more »... ptional profiling revealed that Sox30 and Dmrt1 similarly exhibited a high expression in tilapia testes from 90 days after hatching (dah) to 300 dah, and the transcription of the Sox30 gene was reduced about one-fold in the testes of male tilapia with Dmrt1 knockdown. Further dual-luciferase reporter assay confirmed that Dmrt1 overexpression significantly promoted transcriptional activity of the Sox30 promoter and this promotion was decreased following the mutation of putative CRE for Dmrt1 within the Sox30 promoter. Chromatin immunoprecipitation-based PCR (ChIP-PCR) and electrophoretic mobility shift assay (EMSA) demonstrated that Dmrt1 directly binds to putative CRE within the Sox30 promoter. These results together indicate that Dmrt1 positively regulates the transcription of the tilapia Sox30 gene by directly binding to specific CRE within the Sox30 promoter.
Due to the complex working medium of oil in construction engineering, the waterproof valve in mixing machinery can easily cause different degrees of failure. Moreover, under adverse working conditions and complicated noise backgrounds, it is very difficult to detect the fault of waterproof valves. Thus, a fault diagnosis method is proposed, especially for the fault detection of waterproof valves as a key component in the construction of mixing machinery. This fault diagnosis method is based ondoi:10.3390/en15082796 fatcat:ywpo2c2uhjdbvkbuv6qoapgkk4
more »... new adaptive feature extraction model, with multi-path signals to the improved deep residual shrinkage network–stacked denoising convolutional autoencoder (named DRSN–SDCAE). Firstly, the noisy vibration signals collected by the two vibration sensors are preprocessed, and then transmitted to the parallel structure improved DRSN–SDCAE for adaptive denoising and feature extraction. Finally, these results are fused through the feature fusion strategy to realize the effective fault diagnosis of the waterproof valve. The effectiveness of this method was verified through theory and experiments. The experimental results show that the proposed fault diagnosis method based on the improved DRSN–SDCAE model can automatically and effectively extract fault features from noise for fault diagnosis without relying on signal processing technology and diagnosis experiences. When compared with other intelligent fault diagnosis methods, the features extracted from multi-path inputs were more comprehensive than those extracted from single-path inputs, and contained more complete features of hidden data, which significantly improved fault diagnosis accuracy based on these fault features. The contribution of this paper is to learn fault features autonomously in signals with strong and complex noise through a deep network structure, which extends the fault diagnosis method to the field of construction machinery to improve the safe operation and maintainability of engineering machinery.
This paper aimed to reveal elastohydrodynamic lubrication characteristics for surface-textured slipper bearing of axial piston pump. The proposed model was established including slipper-tilting motion and surface deformation. Further, a numerical simulation was conducted under hydrodynamic and elastohydrodyamic lubrication conditions. Numerical solutions were obtained under this lubrication conditions in terms of the film pressure, film thicknesses, and bearing stiffness. The simulation resultsdoi:10.1007/s40430-020-02282-w fatcat:ajqjnmp2affv3ajs5fotaevvke
more »... reveal that the film pressure in EHD solution increases slightly with the growth of the area density within the range of 10-30% and then tends to remain stable. When the area density of dimple is set to 38%, the dimensionless stiffness of oil film shows the highest value. If the dimple depth is set to 0.8 μm, there exists the maximum dimensionless stiffness of oil film in EHD solution when the optimum dimple depth-to-diameter ratio is set to 0.22. Journal of the Brazilian Society of Mechanical Sciences and Engineering (2020) 42:199 Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
The uncertainty in parameter estimation arises from structural systems' 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' space and to infer thedoi:10.3390/app9224959 fatcat:c34favyyabewhocl2oapvwvyga
more »... terior 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.
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 modifieddoi:10.3390/app10155245 fatcat:wmfz6rq54zdxxh7f46wv7juc5m
more »... o 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.
*Contact Author: Hesheng Tang, Associate Professor, Institute of Structural Engineering and Disaster Reduction, College of Civil Engineering, Tongji University, Siping Road 1239, Shanghai 200092, P.R. ...doi:10.3130/jaabe.14.241 fatcat:tcgfg5om6jgw3adp7wnc5oo7dq
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