Separation Gap Estimation in Dynamic Systems Actuated by Casimir Force

2011 ◽  
Vol 254 ◽  
pp. 21-24
Author(s):  
Song Cui ◽  
Yeng Chai Soh
Keyword(s):  
Surface Roughness ◽  
Simulation Study ◽  
Dynamic Systems ◽  
Casimir Force ◽  
Estimation Method ◽  
Finite Conductivity ◽  
Unknown Parameters ◽  
Experimental Conditions

In this paper, a new estimation method is proposed to estimate the separation gap and other unknown parameters in Casimir force actuated systems. Real experimental conditions like the finite conductivity and surface roughness are considered as well. Simulation study shows that the method is accurate even when the system has severe nonlinearity.

scholarly journals Comparative investigation of lasing and amplification performance in cryogenic Yb:YLF systems

2021 ◽  
Vol 127 (3) ◽  
Author(s):  
Umit Demirbas ◽  
Martin Kellert ◽  
Jelto Thesinga ◽  
Yi Hua ◽  
Simon Reuter ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Estimation Method ◽  
Laser Cavity ◽  
Comparative Investigation ◽  
Limiting Factor ◽  
Experimental Conditions ◽  
Temperature Estimation ◽  
Transverse Temperature ◽  
First Time

AbstractWe present detailed experimental results with cryogenic Yb:YLF gain media in rod-geometry. We have comparatively investigated continuous-wave (cw) lasing and regenerative amplification performance under different experimental conditions. In the cw lasing experiments effect of crystal doping, cw laser cavity geometry and pump wavelength on lasing performance were explored. Regenerative amplification behavior was analyzed and the role of depolarization losses on performance was investigated. A recently developed temperature estimation method was also employed for the first time in estimating average crystal temperature under lasing conditions. It is shown that the thermal lens induced by transverse temperature gradients is the main limiting factor and strategies for future improvements are discussed. To the best of our knowledge, the achieved results in this study (375 W in cw, and 90 W in regenerative amplification) are the highest average powers ever obtained from this system via employing the broadband E//a axis.

scholarly journals New class of Lindley distributions: properties and applications

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Duha Hamed ◽  
Ahmad Alzaghal
Keyword(s):  
Maximum Likelihood ◽  
Maximum Likelihood Estimation ◽  
Simulation Study ◽  
Likelihood Estimation ◽  
Statistical Properties ◽  
Data Sets ◽  
Lifetime Data ◽  
Unknown Parameters ◽  
Lindley Distribution ◽  
New Class

AbstractA new generalized class of Lindley distribution is introduced in this paper. This new class is called the T-Lindley{Y} class of distributions, and it is generated by using the quantile functions of uniform, exponential, Weibull, log-logistic, logistic and Cauchy distributions. The statistical properties including the modes, moments and Shannon’s entropy are discussed. Three new generalized Lindley distributions are investigated in more details. For estimating the unknown parameters, the maximum likelihood estimation has been used and a simulation study was carried out. Lastly, the usefulness of this new proposed class in fitting lifetime data is illustrated using four different data sets. In the application section, the strength of members of the T-Lindley{Y} class in modeling both unimodal as well as bimodal data sets is presented. A member of the T-Lindley{Y} class of distributions outperformed other known distributions in modeling unimodal and bimodal lifetime data sets.

Identification of Viscously Damped Distributed Structural Dynamic Systems

1991 ◽  
Author(s):  
R. Chander ◽  
M. Meyyappa ◽  
S. Hanagud
Keyword(s):  
Dynamic Systems ◽  
Beam Theory ◽  
Continuous Functions ◽  
Model Parameters ◽  
Unknown Parameters ◽  
Structural Dynamic ◽  
Domain Identification ◽  
Forcing Function ◽  
Cardinal Splines ◽  
Stiffness And Damping

Abstract A frequency domain identification technique applicable to damped distributed structural dynamic systems is presented. The technique is developed for beams whose behavior can be modeled using the Euler-Bernoulli beam theory. External damping of the system is included by means of a linear viscous damping model. Parameters to be identified, mass, stiffness and damping distributions are assumed to be continuous functions over the beam. The response at a discrete number of points along the length of the beam for a given forcing function is used as the data for identification. The identification scheme involves approximating the infinite dimensional response and parameter spaces by using quintic B-splines and cubic cardinal splines, respectively. A Galerkin type weighted residual procedure, in conjunction with the least squares technique, is employed to determine the unknown parameters. Numerically simulated response data for an applied impulse load are utilized to validate the developed technique. Estimated values for the mass, stiffness and damping distributions are discussed.

INVESTIGATION OF SINGLE-POINT DRESSING OVERLAP RATIO AND DIAMOND-ROLL DRESSING INTERFERENCE ANGLE ON SURFACE ROUGHNESS IN GRINDING

2010 ◽  
Vol 34 (2) ◽  
pp. 295-308 ◽  
Author(s):  
Akram Saad ◽  
Robert Bauer ◽  
Andrew Warkentin
Keyword(s):  
Surface Roughness ◽  
Material Removal Rate ◽  
Empirical Model ◽  
Material Removal ◽  
Removal Rate ◽  
Single Point ◽  
Experimental Conditions ◽  
Workpiece Surface ◽  
Different Depths ◽  
Overlap Ratio

This paper investigates the effect of both single-point and diamond-roll dressing techniques on the workpiece surface roughness in grinding. Two empirical surface roughness models are studied – one that incorporates single-point dressing parameters, and another that incorporates diamond-roll dressing parameters. For the experimental conditions used in this research, the corresponding empirical model coefficients are found to have a linear relationship with the inverse of the overlap ratio for single-point dressing and the interference angle for diamond-roll dressing. The resulting workpiece surface roughness models are then experimentally validated for different depths of cut, workpiece speeds and dressing conditions. In addition, the models are used to derive a relationship between overlap ratio for single-point dressing, and interference angle for diamond-roll dressing such that both dressing techniques produce a similar surface finish for a given material removal rate.

scholarly journals A New Gaze Estimation Method Based on Homography Transformation Derived from Geometric Relationship

2020 ◽  
Vol 10 (24) ◽  
pp. 9079
Author(s):  
Kaiqing Luo ◽  
Xuan Jia ◽  
Hua Xiao ◽  
Dongmei Liu ◽  
Li Peng ◽  
...  
Keyword(s):  
Estimation Method ◽  
Gaze Estimation ◽  
Estimation Model ◽  
Experimental Accuracy ◽  
Unknown Parameters ◽  
The Gaze ◽  
Marquardt Algorithm ◽  
Mapping Equation ◽  
Estimation System ◽  
Homography Transformation

In recent years, the gaze estimation system, as a new type of human-computer interaction technology, has received extensive attention. The gaze estimation model is one of the main research contents of the system. The quality of the model will directly affect the accuracy of the entire gaze estimation system. To achieve higher accuracy even with simple devices, this paper proposes an improved mapping equation model based on homography transformation. In the process of experiment, the model mainly uses the “Zhang Zhengyou calibration method” to obtain the internal and external parameters of the camera to correct the distortion of the camera, and uses the LM(Levenberg-Marquardt) algorithm to solve the unknown parameters contained in the mapping equation. After all the parameters of the equation are determined, the gaze point is calculated. Different comparative experiments are designed to verify the experimental accuracy and fitting effect of this mapping equation. The results show that the method can achieve high experimental accuracy, and the basic accuracy is kept within 0.6∘. The overall trend shows that the mapping method based on homography transformation has higher experimental accuracy, better fitting effect and stronger stability.

scholarly journals A New Extended Two-Parameter Distribution: Properties, Estimation Methods, and Applications in Medicine and Geology

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1578 ◽  
Author(s):  
Hazem Al-Mofleh ◽  
Ahmed Z. Afify ◽  
Noor Akma Ibrahim
Keyword(s):  
Estimation Method ◽  
Estimation Methods ◽  
Parameter Distribution ◽  
Model Parameters ◽  
Unknown Parameters ◽  
Proposed Model ◽  
Rate Functions ◽  
The Mean ◽  
Modeling Data ◽  
Two Parameter

In this paper, a new two-parameter generalized Ramos–Louzada distribution is proposed. The proposed model provides more flexibility in modeling data with increasing, decreasing, J-shaped, and reversed-J shaped hazard rate functions. Several statistical properties of the model were derived. The unknown parameters of the new distribution were explored using eight frequentist estimation approaches. These approaches are important for developing guidelines to choose the best method of estimation for the model parameters, which would be of great interest to practitioners and applied statisticians. Detailed numerical simulations are presented to examine the bias and the mean square error of the proposed estimators. The best estimation method and ordering performance of the estimators were determined using the partial and overall ranks of all estimation methods for various parameter combinations. The performance of the proposed distribution is illustrated using two real datasets from the fields of medicine and geology, and both datasets show that the new model is more appropriate as compared to the Marshall–Olkin exponential, exponentiated exponential, beta exponential, gamma, Poisson–Lomax, Lindley geometric, generalized Lindley, and Lindley distributions, among others.

Artificial neural networks and adaptive neuro-fuzzy inference systems for parameter identification of dynamic systems

2020 ◽  
Vol 39 (5) ◽  
pp. 6145-6155
Author(s):  
Ramin Vatankhah ◽  
Mohammad Ghanatian
Keyword(s):  
Differential Equations ◽  
Dynamic Systems ◽  
Fuzzy Inference ◽  
Dynamic Equations ◽  
Control Analysis ◽  
Unknown Parameters ◽  
Inference System ◽  
Neuro Fuzzy ◽  
Artificial Neural ◽  
Inference Systems

There would always be some unknown geometric, inertial or any other kinds of parameters in governing differential equations of dynamic systems. These parameters are needed to be numerically specified in order to make these dynamic equations usable for dynamic and control analysis. In this study, two powerful techniques in the field of Artificial Intelligence (AI), namely Artificial Neural Network (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) are utilized to explain how unknown parameters in differential equations of dynamic systems can be identified. The data required for training and testing the ANN and the ANFIS are obtained by solving the direct problem i.e. solving the dynamic equations with different known parameters and input stimulations. The governing ordinary differential equations of the system is numerically solved and the output values in different time steps are obtained. The output values of the system and their derivatives, the time and the inputs are given to the ANN and the ANFIS as their inputs and the unknown parameters in the dynamic equations are estimated as the outputs. Finally, the performances of the ANN and the ANFIS for identifying parameters of the system are compared based on the test data Percent Root Mean Square Error (% RMSE) values.

LDA Measurements in Rough Surface ZPG Turbulent Boundary layers

2006 ◽  
Author(s):  
Brian Brzek ◽  
Rau´l Bayoa´n Cal ◽  
Gunnar Johansson ◽  
Luciano Castillo
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Laser Doppler Anemometry ◽  
Single Point ◽  
Roughness Parameter ◽  
Reynolds Stresses ◽  
Experimental Conditions ◽  
Boundary Layer Equations ◽  
Entire Boundary ◽  
Boundary Layer Development

A new set of experiments have been performed in order to study the effects of the upstream conditions and the surface roughness on a zero pressure gradient turbulent boundary layer. In order to properly capture the x-dependence of the single point statistics, consecutive measurements of 11 streamwise locations were performed. These 2-D Laser Doppler Anemometry (LDA) measurements enable us to use the full boundary layer equations in order to calculate the skin friction and determine the boundary layer development which is not possible in the majority of experiments on rough surfaces. It will be shown that for fixed experimental conditions (i.e., fixed upstream wind tunnel speed, trip wire, etc), the velocity deficit profiles collapse for each of the scalings investigated but only the Zagarola/Smits scaling (1998) could collapse all the different experimental conditions into a single curve. In addition, the Reynolds stresses were increasingly affected by the surface roughness as the roughness parameter, k+, increased. Moreover, it was found that the shape of the Reynolds stress profiles was very different throughout the entire boundary layer, particularly the < u2 > component. This is likely the result of the flow becoming more isotropic for increased k+, and will be seen in the anisotropy coefficients. Moreover, increased production of < u2 > and < uv > due to roughness is also seen throughout the entire boundary layer although its overall role in the changing shape of the < u2 > profiles still needs to be determined. The effect of roughness on the boundary layer parameters is also evident and their x-dependence is also shown.

A multi-scale modeling and simulation study to investigate the effect of roughness of a surface on its self-cleaning performance

2020 ◽  
Vol 5 (7) ◽  
pp. 1277-1289 ◽  
Author(s):  
Sushanta K. Sethi ◽  
Manjinder Singh ◽  
Gaurav Manik
Keyword(s):  
Surface Roughness ◽  
Modeling And Simulation ◽  
Simulation Study ◽  
Multi Scale ◽  
Cleaning Performance ◽  
Scale Modeling ◽  
Multi Scale Modeling ◽  
Self Cleaning

The importance of surface roughness on wettability is vital in developing novel techniques and materials for fabrication of self-cleaning coatings.

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