An Updated Analytical Structural Pounding Force Model Based on Viscoelasticity of Materials

Based on the summary of existing pounding force analytical models, an updated pounding force analysis method is proposed by introducing viscoelastic constitutive model and contact mechanics method. Traditional Kelvin viscoelastic pounding force model can be expanded to 3-parameter linear viscoelastic model by separating classic pounding model parameters into geometry parameters and viscoelastic material parameters. Two existing pounding examples, the poundings of steel-to-steel and concrete-to-concrete, are recalculated by utilizing the proposed method. Afterwards, the calculation results are compared with other pounding force models. The results show certain accuracy in proposed model. The relative normalized errors of steel-to-steel and concrete-to-concrete experiments are 19.8% and 12.5%, respectively. Furthermore, a steel-to-polymer pounding example is calculated, and the application of the proposed method in vibration control analysis for pounding tuned mass damper (TMD) is simulated consequently. However, due to insufficient experiment details, the proposed model can only give a rough trend for both single pounding process and vibration control process. Regardless of the cheerful prospect, the study in this paper is only the first step of pounding force calculation. It still needs a more careful assessment of the model performance, especially in the presence of inelastic response.

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Distilling Deep Structural Facial Relationships for FAU Intensity Estimation

10.36227/techrxiv.14157080.v1 ◽

2021 ◽

Author(s):

Yingruo Fan ◽

Jacqueline CK Lam ◽

Victor On Kwok Li

Keyword(s):

Structural Characteristics ◽

Model Performance ◽

Training Model ◽

Model Parameters ◽

Intensity Estimation ◽

Structural Relationships ◽

Proposed Model ◽

Comparable Performance ◽

Knowledge Distillation ◽

The Difference

<div> <div> <div> <p>Facial emotions are expressed through a combination of facial muscle movements, namely, the Facial Action Units (FAUs). FAU intensity estimation aims to estimate the intensity of a set of structurally dependent FAUs. Contrary to the existing works that focus on improving FAU intensity estimation, this study investigates how knowledge distillation (KD) incorporated into a training model can improve FAU intensity estimation efficiency while achieving the same level of performance. Given the intrinsic structural characteristics of FAU, it is desirable to distill deep structural relationships, namely, DSR-FAU, using heatmap regression. Our methodology is as follows: First, a feature map-level distillation loss was applied to ensure that the student network and the teacher network share similar feature distributions. Second, the region-wise and channel-wise relationship distillation loss functions were introduced to penalize the difference in structural relationships. Specifically, the region-wise relationship can be represented by the structural correlations across the facial features, whereas the channel-wise relationship is represented by the implicit FAU co-occurrence dependencies. Third, we compared the model performance of DSR-FAU with the state-of-the-art models, based on two benchmarking datasets. Our proposed model achieves comparable performance with other baseline models, though requiring a lower number of model parameters and lower computation complexities. </p> </div> </div> </div>

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A nonlinear fractional-order damage model of stress relaxation of net-like red soil

Scientific Reports ◽

10.1038/s41598-021-02317-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mingwu Wang ◽

Xinyu Xu ◽

Qiuyan Liu ◽

Yingxun Ding ◽

Fengqiang Shen

Keyword(s):

Stress Relaxation ◽

Fractional Order ◽

Damage Model ◽

Red Soil ◽

Analytical Models ◽

Model Parameters ◽

Nonlinear Characteristics ◽

Loading Mode ◽

Proposed Model ◽

Analytical Result

AbstractIt is essential to precisely describe the nonlinear characteristics of the stress relaxation behavior to ensure the long-term stability of geotechnical structures in the net-like red soil. A novel damage model of variable fractional-order was discussed here to accurately analyze the progress of stress relaxation for the net-like red soil. Moreover, unsaturated triaxial experiments on stress relaxation under a step-loading mode were performed to identify model parameters and investigate the nonlinear relaxation characteristics of the net-like red soil. The feasibility and validity of the proposed model were furthermore verified by comparisons with the experimental results and fitting curves obtained from the Nishihara model and the generalized Kelvin model. Results show that the analytical result by the proposed model is consistent with the measured data, and the proposed model can better depict the nonlinear characteristics of stress relaxation relative to other analytical models. It can better exhibit the relaxation evolution of soil compared with the conventional models.

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Modelling of simple shear tests on volcanic unsaturated sands

E3S Web of Conferences ◽

10.1051/e3sconf/202019502021 ◽

2020 ◽

Vol 195 ◽

pp. 02021

Author(s):

Mariagiovanna Moscariello ◽

Yanni Chen ◽

Sabatino Cuomo ◽

Giuseppe Buscarnera

Keyword(s):

Simple Shear ◽

Unsaturated Soils ◽

Model Performance ◽

Frictional Resistance ◽

Flow Rule ◽

Model Parameters ◽

Shear Tests ◽

Soil Response ◽

Proposed Model ◽

Unsaturated Sands

In landslide susceptibility analysis, a relevant issue is the proper modelling of the complex mechanisms that regulate the failure and post-failure stages. In this paper, simple shear experiments replicating the kinematics of failure in landslide-prone areas are interpreted through an elastoplastic strain-hardening constitutive model for both saturated and unsaturated soils. The material tested is an air-fall volcanic (pyroclastic) soil from Southern Italy which originated from the explosive activity of the Somma-Vesuvius volcanic apparatus. Data from triaxial and shear tests performed on remoulded specimens characterized by saturated and unsaturated conditions are used to calibrate the model parameters. The evolution of shear stress, volumetric and shear strain measured during the experiments are reproduced by means of a model formulation specific for simple shear conditions. To capture the strength emerging under different states of saturation, non-associated flow rule, and a suction-dependent yield surface are used. Examination of the experimental data available for various testing conditions enabled the quantification of the variability of fundamental model constants, such as those controlling frictional resistance and water retention behaviour. To account for such scatter in the physical properties, the constitutive analyses are performed by employing varying model constants within a band of admissible values. The resulting model performance is validated by comparing the simulations with the experimental results at different saturation conditions. The results show that the combination of the proposed model with a data-driven determination of the range of variation of hydro-mechanical properties is crucial to satisfactorily simulate the essential features of the soil response under a variety of simple shear testing regimes.

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On the Adequacy of Representing Water Reflectance by Semi-Analytical Models in Ocean Color Remote Sensing

Remote Sensing ◽

10.3390/rs11232820 ◽

2019 ◽

Vol 11 (23) ◽

pp. 2820

Author(s):

Jing Tan ◽

Robert Frouin ◽

Didier Ramon ◽

François Steinmetz

Keyword(s):

Ocean Color ◽

Atmospheric Correction ◽

Model Performance ◽

Analytical Models ◽

Model Parameters ◽

Water Signal ◽

Wide Range ◽

Reflectance Model ◽

The Impact ◽

Best Fit

Deterministic or statistical inversion schemes to retrieve ocean color from space often use a simplified water reflectance model that may introduce unrealistic constraints on the solution, a disadvantage compared with standard, two-step algorithms that make minimal assumptions about the water signal. In view of this, the semi-analytical models of Morel and Maritorena (2001), MM01, and Park and Ruddick (2005), PR05, used in the spectral matching POLYMER algorithm (Steinmetz et al., 2011), are examined in terms of their ability to restitute properly, i.e., with sufficient accuracy, water reflectance. The approach is to infer water reflectance at MODIS wavelengths, as in POLYMER, from theoretical simulations (using Hydrolight with fluorescence and Raman scattering) and, separately, from measurements (AERONET-OC network). A wide range of Case 1 and Case 2 waters, except extremely turbid waters, are included in the simulations and sampled in the measurements. The reflectance model parameters that give the best fit with the simulated data or the measurements are determined. The accuracy of the reconstructed water reflectance and its effect on the retrieval of inherent optical properties (IOPs) is quantified. The impact of cloud and aerosol transmittance, fixed to unity in the POLYMER scheme, on model performance is also evaluated. Agreement is generally good between model results and Hydrolight simulations or AERONET-OC values, even in optically complex waters, with discrepancies much smaller than typical atmospheric correction errors. Significant differences exist in some cases, but having a more intricate model (i.e., using more parameters) makes convergence more difficult. The trade-off is between efficiency/robustness and accuracy. Notable errors are obtained when using the model estimates to retrieve IOPs. Importantly, the model parameters that best fit the input data, in particular chlorophyll-a concentration, do not represent adequately actual values. The reconstructed water reflectance should be used in bio-optical algorithms. While neglecting cloud and aerosol transmittances degrades the accuracy of the reconstructed water reflectance and the retrieved IOPs, it negligibly affects water reflectance ratios and, therefore, any variable derived from such ratios.

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Research of Self-Learning of Plate Deformation Resistance Based on Genetic Algorithm

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.154-155.260 ◽

2010 ◽

Vol 154-155 ◽

pp. 260-264

Author(s):

Chun Yu He ◽

Zhi Jie Jiao ◽

Di Wu

Keyword(s):

Genetic Algorithm ◽

Rolling Force ◽

Deformation Resistance ◽

Learning System ◽

Model Parameters ◽

Decision Variable ◽

Force Model ◽

Calculation Error ◽

Force Calculation ◽

Self Learning

The model parameters value of deformation resistance determines the prediction accuracy of rolling force model during the plate rolling. According to the influencing factors analysis of rolling force calculation error, the genetic algorithm was introduced into the self-learning method of deformation resistance, and searches the optimal value of deformation resistance on the basic of space exploration and optimization ability of genetic algorithm. The decision variable selection, the coding and decoding, the fitness evaluation and the terminal conditions process were implemented during development process of self-learning system. The results show that the optimization speed and accuracy can meet production requirement.

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Fuzzy Modeling of Urban Water Supply Crisis

10.5772/intechopen.95882 ◽

2021 ◽

Author(s):

Welitom Ttatom Pereira da Silva ◽

Marco Antonio Almeida de Souza

Keyword(s):

Water Supply ◽

Conceptual Model ◽

Influencing Factors ◽

Water Consumption ◽

Model Performance ◽

Real Data ◽

Model Parameters ◽

Urban Water ◽

Urban Water Supply ◽

Proposed Model

The chaotic growth of cities results in numerous problems related to public health and urban environment. One of these problems is the urban water supply system crisis. This research aims to develop a mathematical model for urban water supply crises (UWC) able to deal with the ambiguity of the real available data. The applied methodology comprises the following steps: (i) identifying the influencing factors in UWC; (ii) proposing a conceptual model for the description of UWC; (iii) collecting and simulating the necessary and available data; (iv) optimizing the conceptual model parameters; and (v) verifying the proposed model performance. The results indicate that there are many influencing factors in UWC. The model developed comprises two parts or two sub-models. The first sub-model explains water consumption, and the second sub-model explains water availability. In the first sub-model, the functions are related to the factors that influence water consumption. In the second sub-model, the functions are related to the factors that influence the availability of water. This research also aims to analyze the possibility of applying Fuzzy Logic to deal with the ambiguity of real data. It was concluded that, with the proposed model, the UWC was modeled appropriately. The model proposed can help to predict the impact of actions such as reducing losses, reducing pressure on the water supply network and intermittent supply on the intensity of water crisis cases in cities.

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Vibration control analysis of the power head for a rotary drilling rig

Advances in Mechanical Engineering ◽

10.1177/1687814019891040 ◽

2019 ◽

Vol 11 (11) ◽

pp. 168781401989104

Author(s):

Renzhi Wu ◽

Lei Qin ◽

Jixiang Diao

Keyword(s):

Vibration Control ◽

Analytical Models ◽

Control Analysis ◽

Control Performance ◽

Rotary Drilling ◽

Construction Engineering ◽

Displacement Response ◽

Drilling Rig ◽

Steel Rope ◽

Relationship Of

Impacting between the multilayer Kelly bar and the power head has a detrimental effect on the drilling system and may cause huge losses to the construction engineering and machinery. This study is a further development of the vibro-impact mechanism, and especially, the study considers the constraint of the steel rope on the multilayer Kelly bar. Efficient analytical models are presented, and the total responses are obtained. Three types of displacement response are found by changing the matching relationship of global parameters. The first type has the optimal vibration control performance with the shortest path and no periodicity. The second type is inferior to the first type. The third type has the worst vibration-control performance with the longest path and periodicity. Then this article proposes the general feasibility to get the first type of displacement response and the most effective way is controlling the steel rope velocity. The research provides the foundation for the intelligent control of steel rope velocity on the rig machine.

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Modeling and Parameter Identification of Harmonic Drive Systems

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.2801484 ◽

1998 ◽

Vol 120 (4) ◽

pp. 439-444 ◽

Cited By ~ 76

Author(s):

H. D. Taghirad ◽

P. R. Be´langer

Keyword(s):

Dynamic Behavior ◽

Model Performance ◽

Sensitivity Study ◽

Model Parameters ◽

Harmonic Drive ◽

Nonlinear Regression Models ◽

Proposed Model ◽

Stiffness Model ◽

Drive Systems ◽

Compact Geometry

The unique performance features of harmonic drives, such as high gear ratios and high torque capacities in a compact geometry, justify their widespread industrial application. However, harmonic drive can exhibit surprisingly more complex dynamic behavior than conventional gear transmission. In this paper a systematic way to capture and rationalize the dynamic behavior of the harmonic drive systems is developed. Simple and accurate models for compliance, hysteresis, and friction are proposed, and the model parameters are estimated using least-squares approximation for linear and nonlinear regression models. A statistical measure of variation is defined, by which the reliability of the estimated parameter for different operating condition, as well as the accuracy and integrity of the proposed model is quantified. By these means, it is shown that a linear stiffness model best captures the behavior of the system when combined with a good model for hysteresis. Moreover, the frictional losses of harmonic drive are modeled at both low and high velocities. The model performance is assessed by comparing simulations with the experimental results on two different harmonic drives. Finally, the significance of individual components of the nonlinear model is assessed by a parameter sensitivity study using simulations.

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Creep Force Characteristics of Wheel/Rail Contact Under Friction Control

Volume 9: Transportation Systems; Safety Engineering, Risk Analysis and Reliability Methods; Applied Stochastic Optimization, Uncertainty and Probability ◽

10.1115/imece2011-62626 ◽

2011 ◽

Author(s):

Shunpei Yamashita ◽

Akihiko Sakamaki ◽

Hiroyuki Sugiyama

Keyword(s):

Model Parameters ◽

Force Model ◽

Friction Modifiers ◽

Test Rig ◽

Friction Control ◽

Proposed Model ◽

Creep Force ◽

Equivalent Shear Modulus ◽

Semi Empirical ◽

Force Characteristics

In this investigation, a creep force model for contact with friction modifiers is developed and validated by comparing with the experimental results. To this end, a creep force model is developed by introducing a concept of equivalent shear modulus of rigidity, and a two-roller test rig is developed and used for validating the proposed model. Furthermore, relationships between the model parameters and the amount of friction modifiers applied to the contact patch are discussed. It is demonstrated that good agreements are obtained for the creep force characteristics obtained using the proposed model and the two-roller test rig developed in this investigation. Furthermore, it is shown that the proposed model can be used as a semi-empirical model, in which one can define the model parameter as a curve-fitting parameter and, at the same time, physical interpretations regarding the lubrication state between the wheel and rail interface can be obtained using the identified parameters.

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