scholarly journals Algorithm for Estimating the Laser Beam, Matrix Photo Receiver on the Background of the Gaussian Noise Using Full Sufficient Statistics of the Received Scattered Radiation

2021 ◽  
pp. 265-271
Author(s):  
Yuri L. Koziratsky ◽  
Roman G. Khilchenko ◽  
Ruslan E. Merkulov ◽  
Anton A. Koziratsky
Keyword(s):  
Parameter Estimation ◽  
Laser Radiation ◽  
Laser Beam ◽  
Gaussian Noise ◽  
Scattered Radiation ◽  
Finite Sample ◽  
Sufficient Statistics ◽  
Distribution Parameters ◽  
Photo Receiver

An algorithm for estimating the position of the laser beam by the component scattered in the atmosphere by a matrix photodetector against a background of Gaussian noise is developed. The algorithm is based on the Lehman-Scheffe theorem, which allows one to obtain effective estimates of the distribution parameters using complete sufficient statistics for reports of the observed implementation of scattered laser radiation. The obtained estimates provide the best quality of parameter estimation for any finite sample sizes and do not require additional studies

scholarly journals Effect of Laser Beam Focusing Adjustment on the Processing Quality of Aluminum Nitride Ceramic Micro-Holes

2021 ◽  
Vol 1865 (2) ◽  
pp. 022004
Author(s):  
Chunyan Yang ◽  
Yun Hao ◽  
Yangping Li ◽  
Bozhe Wang ◽  
Hai Yuan ◽  
...  
Keyword(s):  
Aluminum Nitride ◽  
Laser Beam ◽  
Processing Quality ◽  
Beam Focusing ◽  
Micro Holes

scholarly journals On Asymptotic Efficiency of the M2M4 Signal-to-Noise Estimator for Deterministic Complex Sinusoids

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 4950
Author(s):  
Gianmarco Romano
Keyword(s):  
Covariance Matrix ◽  
Gaussian Noise ◽  
Asymptotic Efficiency ◽  
Noise Power ◽  
Finite Sample ◽  
Signal To Noise ◽  
Numerical Examples ◽  
Unknown Phase ◽  
The Moment ◽  
Asymptotically Efficient

The moment-based M2M4 signal-to-noise (SNR) estimator was proposed for a complex sinusoidal signal with a deterministic but unknown phase corrupted by additive Gaussian noise by Sekhar and Sreenivas. The authors studied its performances only through numerical examples and concluded that the proposed estimator is asymptotically efficient and exhibits finite sample super-efficiency for some combinations of signal and noise power. In this paper, we derive the analytical asymptotic performances of the proposed M2M4 SNR estimator, and we show that, contrary to what it has been concluded by Sekhar and Sreenivas, the proposed estimator is neither (asymptotically) efficient nor super-efficient. We also show that when dealing with deterministic signals, the covariance matrix needed to derive asymptotic performances must be explicitly derived as its known general form for random signals cannot be extended to deterministic signals. Numerical examples are provided whose results confirm the analytical findings.

scholarly journals 1178 J, 527 nm near diffraction limited laser based on a complete closed-loop adaptive optics controlled off-axis multi-pass amplification laser system

2021 ◽  
Vol 9 ◽  
Author(s):  
Deen Wang ◽  
Xin Zhang ◽  
Wanjun Dai ◽  
Ying Yang ◽  
Xuewei Deng ◽  
...  
Keyword(s):  
Laser Beam ◽  
Adaptive Optics ◽  
Closed Loop ◽  
Focal Spot ◽  
Beam Quality ◽  
Laser System ◽  
Diffraction Limit ◽  
Kdp Crystal ◽  
Main Amplifier

Abstract A 1178 J near diffraction limited 527 nm laser is realized in a complete closed-loop adaptive optics (AO) controlled off-axis multi-pass amplification laser system. Generated from a fiber laser and amplified by the pre-amplifier and the main amplifier, a 1053 nm laser beam with the energy of 1900 J is obtained and converted into a 527 nm laser beam by a KDP crystal with 62% conversion efficiency, 1178 J and beam quality of 7.93 times the diffraction limit (DL). By using a complete closed-loop AO configuration, the static and dynamic wavefront distortions of the laser system are measured and compensated. After correction, the diameter of the circle enclosing 80% energy is improved remarkably from 7.93DL to 1.29DL. The focal spot is highly concentrated and the 1178 J, 527 nm near diffraction limited laser is achieved.

Improvement of Build Speed and Quality of H13 Tool Steel Processed by Laser-Beam Powder Bed Fusion with a High-Power Laser

2021 ◽  
Vol 68 (10) ◽  
pp. 415-421
Author(s):  
Takashi MIZOGUCHI ◽  
Takaya NAGAHAMA ◽  
Makoto TANO ◽  
Shigeru MATSUNAGA ◽  
Takayuki YOSHIMI ◽  
...  
Keyword(s):  
Laser Beam ◽  
Tool Steel ◽  
High Power ◽  
Powder Bed Fusion ◽  
High Power Laser ◽  
Power Laser ◽  
Powder Bed ◽  
H13 Tool Steel

Particularity of the Forming Barcode Image on the Surface of Machine Parts when Marking with a Pulsed Laser

2015 ◽  
Vol 806 ◽  
pp. 83-87 ◽  
Author(s):  
Oksana Ganzulenko ◽  
Ani Petkova
Keyword(s):  
Laser Beam ◽  
Pulsed Laser ◽  
Impact Zone ◽  
Influence Of Process Parameters ◽  
Laser Marking ◽  
Pulse Laser Beam ◽  
Local Impact ◽  
Machine Parts ◽  
Metal Materials

The article is devoted to some aspects of laser marking technology for machine parts. We consider the local impact zone effect of the pulse laser beam on the surface of metal materials. The results describing the influence of process parameters on the quality of the being marked images by pulsed laser are submitted. The examples of using barcode marking on several materials for machine parts in selected technological modes of installation are given.

scholarly journals Efficient gradient-based parameter estimation for dynamic models using qualitative data

2021 ◽  
Author(s):  
Leonard Schmiester ◽  
Daniel Weindl ◽  
Jan Hasenauer
Keyword(s):  
Parameter Estimation ◽  
Qualitative Data ◽  
Dynamic Models ◽  
Unknown Parameters ◽  
Differential Equation Models ◽  
Gradient Calculation ◽  
Order Of Magnitude ◽  
Gradient Based ◽  
Objective Function Values

AbstractMotivationUnknown parameters of dynamical models are commonly estimated from experimental data. However, while various efficient optimization and uncertainty analysis methods have been proposed for quantitative data, methods for qualitative data are rare and suffer from bad scaling and convergence.ResultsHere, we propose an efficient and reliable framework for estimating the parameters of ordinary differential equation models from qualitative data. In this framework, we derive a semi-analytical algorithm for gradient calculation of the optimal scaling method developed for qualitative data. This enables the use of efficient gradient-based optimization algorithms. We demonstrate that the use of gradient information improves performance of optimization and uncertainty quantification on several application examples. On average, we achieve a speedup of more than one order of magnitude compared to gradient-free optimization. Additionally, in some examples, the gradient-based approach yields substantially improved objective function values and quality of the fits. Accordingly, the proposed framework substantially improves the parameterization of models from qualitative data.AvailabilityThe proposed approach is implemented in the open-source Python Parameter EStimation TOolbox (pyPESTO). All application examples and code to reproduce this study are available at https://doi.org/10.5281/zenodo.4507613.

scholarly journals Temperature Calibration Measurements based on Laser-Induced Phosphorescence Technique for Combustion Applications

2015 ◽  
Vol 10 (1) ◽  
Keyword(s):  
Laser Radiation ◽  
Laser Beam ◽  
Intensity Ratio ◽  
Laser Power ◽  
Room Temperature ◽  
Pulsed Laser ◽  
Temperature Calibration ◽  
Phosphor Powder ◽  
Calibration Methods

Phosphor powder and phosphor-binder mixtures are successfully employed for temperature calibration measurements by using laser-induced phosphorescence (LIP) technique with an emphasis on higher precisions and accuracies than other non-intrusive methods. The phosphorescence intensities are used to perform these calibrations in three different strategies. The influence of laser power regular changes on particles heating and the calibration analyses is also carried out. A pulsed laser at 355 nm was used for exciting specimens of the phosphor powder as well as the phosphor-binder mixtures. The laser beam was directed onto the specimens and varied in three laser power levels (LPLs). The samples were kept in an oven with temperatures ranging from room temperature up to 1800 °C. The three strategies which are expressed in terms of non-dimensional intensity versus wavelength (NDI-W), normalised intensity (NI) and intensity ratio (IR) were used for the calibration assessments. A modified IR was compared with two different IRs. A precision of around ± (0.50-1.41)% was attained for different calibration methods. This research confirmed that these calibrations are possible using three different strategies, given high precisions and accuracies. The laser power alternations influenced the NI and do affect neither the NDI-W nor the IR curves. The laser radiation does not play any role for heating the particles of the studied powder.

scholarly journals A Functioning Model of a Dual-Band Radar System That Classifies Targets under the Influence of Interference and Noise

2020 ◽  
Vol 6 (4) ◽  
pp. 112-119
Author(s):  
V. Makarenkov
Keyword(s):  
Gaussian Noise ◽  
Radar System ◽  
White Gaussian Noise ◽  
Dual Band ◽  
Correct Classification ◽  
Noise Interference ◽  
Active Noise ◽  
Complex Target

There is proposed a model of a signal received from a complex target formed by a set of rapidly fluctuating point reflectors. Signal reception is carried out against the background of narrow-broadband active noise interference and white Gaussian noise. A functioning model of a dual-band radar system is proposed, in which the problem of classifying rapidly fluctuating point reflectors as a part of complex target against the background of interference and noise is solved. The article examines the issue of assessing the quality of this model, as well as meeting the re-quirements for ensuring a given value of the probability of correct classification of goals.

scholarly journals Neglect Of Parameter Estimation Uncertainty Can Significantly Overestimate Structural Reliability

2015 ◽  
Vol 15 (2) ◽  
Author(s):  
Árpád Rózsás ◽  
Miroslav Sýkora
Keyword(s):  
Parameter Estimation ◽  
Bayesian Statistics ◽  
Failure Probability ◽  
Structural Reliability ◽  
Probabilistic Models ◽  
Estimation Uncertainty ◽  
Point Estimates ◽  
Distribution Parameters ◽  
Order Of Magnitude ◽  
Parameter Estimation Uncertainty

Abstract Parameter estimation uncertainty is often neglected in reliability studies, i.e. point estimates of distribution parameters are used for representative fractiles, and in probabilistic models. A numerical example examines the effect of this uncertainty on structural reliability using Bayesian statistics. The study reveals that the neglect of parameter estimation uncertainty might lead to an order of magnitude underestimation of failure probability.

Sign in / Sign up

Export Citation Format

Share Document