Метод обработки сигналов трехфазного PDV, устраняющий влияние ускорения на точность определения скорости

2021 ◽  
Vol 47 (21) ◽  
pp. 24
Author(s):  
Т.В. Казиева ◽  
И.Ю. Тищенко ◽  
В.Н. Решетов ◽  
К.Л. Губский ◽  
В.А. Пирог
Keyword(s):  
Measurement Accuracy ◽  
Time Window ◽  
Signal Spectrum ◽  
Optic System ◽  
Speed Measurement ◽  
Number Of Factors ◽  
Proposed Model ◽  
Order Of Magnitude ◽  
Fiber Optic System ◽  
Photonic Doppler Velocimetry

The interference method for determining the speed of objects using direct optical heterodyning (PDV-Photonic Doppler Velocimetry) has become widespread due to the simplicity of setting up the fiber-optic system, the unambiguousness of the results, and wide possibilities for varying the measurement accuracy and temporal resolution. The accuracy of speed measurement can be fractions of a percent, but there are a number of factors that prevent this. For example, a change in the speed of an object, that is, its movement with acceleration, leads to a broadening of the signal spectrum with an increase in the working time window and, as a consequence, to a decrease, rather than an increase in the accuracy of speed measurement. In this paper, we propose a method to compensate for the effect of acceleration on the accuracy of speed measurement. The proposed model for processing the registered signals makes it possible to determine both the acceleration and the speed of the object. The applied algorithm made it possible to avoid spectrum broadening with an increase in the time window and to increase the accuracy of measuring the speed of a freely falling body by an order of magnitude.

The impact of duration observations on precision of results GNSS measurements

2017 ◽  
Vol 921 (3) ◽  
pp. 7-13 ◽  
Author(s):  
S.V. Grishko
Keyword(s):  
Measurement Accuracy ◽  
Functional Dependence ◽  
Observation Time ◽  
Satellite Networks ◽  
Satellite Measurements ◽  
Proposed Model ◽  
Actual Error ◽  
Gnss Measurements ◽  
The Impact ◽  
Qualitative Characteristics

This paper shows that the accuracy of relative satellite measurements depend not only on the length of the baseline, as it is regulated by the rating formula of accuracy of GNSS equipment, but also on the duration of observations. As a result of the strict adjustment much redundant satellite networks with different duration of observations obtained covariance matrix of baselines, the most realistic reflecting the actual error of satellite observations. Research of forms of communication of these errors from length of the baseline and duration of its measurement is executed. A significant influence of solar activity on accuracy of satellite measurements, in general, leads to unequal similar series of measurements made at different periods, for example, in the production of monitoring activities. The model of approximation of the functional dependence of accuracy of the baseline from its length and duration of observations having good qualitative characteristics is offered. Based on the proposed model, we analyzed the dynamics of changes in measurement accuracy with an increase in observation time.

Fluorescent Organofilms for Oxygen Sensing in Organic Solvents Using a Fiber Optic System

The Analyst ◽  
1997 ◽  
Vol 122 (11) ◽  
pp. 1405-1410 ◽  
Author(s):  
N. Velasco-García ◽  
M. J. Valencia-González ◽  
M. E. Díaz-García
Keyword(s):  
Organic Solvents ◽  
Fiber Optic ◽  
Oxygen Sensing ◽  
Optic System ◽  
Fiber Optic System

scholarly journals A multidimensional generalized many-facet Rasch model for rubric-based performance assessment

2021 ◽  
Author(s):  
Masaki Uto
Keyword(s):  
Performance Assessment ◽  
Rasch Model ◽  
Measurement Accuracy ◽  
Estimation Method ◽  
Real Data ◽  
Monte Carlo Algorithm ◽  
Irt Model ◽  
Irt Models ◽  
Proposed Model ◽  
Problem Item

AbstractPerformance assessment, in which human raters assess examinee performance in a practical task, often involves the use of a scoring rubric consisting of multiple evaluation items to increase the objectivity of evaluation. However, even when using a rubric, assigned scores are known to depend on characteristics of the rubric’s evaluation items and the raters, thus decreasing ability measurement accuracy. To resolve this problem, item response theory (IRT) models that can estimate examinee ability while considering the effects of these characteristics have been proposed. These IRT models assume unidimensionality, meaning that a rubric measures one latent ability. In practice, however, this assumption might not be satisfied because a rubric’s evaluation items are often designed to measure multiple sub-abilities that constitute a targeted ability. To address this issue, this study proposes a multidimensional IRT model for rubric-based performance assessment. Specifically, the proposed model is formulated as a multidimensional extension of a generalized many-facet Rasch model. Moreover, a No-U-Turn variant of the Hamiltonian Markov chain Monte Carlo algorithm is adopted as a parameter estimation method for the proposed model. The proposed model is useful not only for improving the ability measurement accuracy, but also for detailed analysis of rubric quality and rubric construct validity. The study demonstrates the effectiveness of the proposed model through simulation experiments and application to real data.

scholarly journals A Synchronous Optimization Model for Multiship Shuttle Tanker Fleet Design and Scheduling Considering Hard Time Window Constraint

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Zhenfeng Jiang ◽  
Dongxu Chen ◽  
Zhongzhen Yang
Keyword(s):  
Time Window ◽  
Programming Model ◽  
Transportation Cost ◽  
Exact Algorithm ◽  
Mixed Integer ◽  
Routing Problem ◽  
Hard Time ◽  
Proposed Model ◽  
Total Transportation Cost ◽  
Time Window Constraints

A Synchronous Optimization for Multiship Shuttle Tanker Fleet Design and Scheduling is solved in the context of development of floating production storage and offloading device (FPSO). In this paper, the shuttle tanker fleet scheduling problem is considered as a vehicle routing problem with hard time window constraints. A mixed integer programming model aiming at minimizing total transportation cost is proposed to model this problem. To solve this model, we propose an exact algorithm based on the column generation and perform numerical experiments. The experiment results show that the proposed model and algorithm can effectively solve the problem.

Enhanced Evaporation of Microscale Droplets With an Infrared Laser

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Luis A. Ferraz-Albani ◽  
Alberto Baldelli ◽  
Chrissy J. Knapp ◽  
Wolfgang Jäger ◽  
Reinhard Vehring ◽  
...  
Keyword(s):  
Water Droplet ◽  
Droplet Evaporation ◽  
Radiant Flux ◽  
Droplet Temperature ◽  
Ambient Conditions ◽  
Drying Time ◽  
Proposed Model ◽  
Environment Temperature ◽  
Order Of Magnitude ◽  
Surface Area Change

Enhancement of water droplet evaporation by added infrared radiation was modeled and studied experimentally in a vertical laminar flow channel. Experiments were conducted on droplets with nominal initial diameters of 50 μm in air with relative humidities ranging from 0% to 90% RH. A 2800 nm laser was used with radiant flux densities as high as 4 × 105 W/m2. Droplet size as a function of time was measured by a shadowgraph technique. The model assumed quasi-steady behavior, a low Biot number liquid phase, and constant gas–vapor phase material properties, while the experimental results were required for model validation and calibration. For radiant flux densities less than 104 W/m2, droplet evaporation rates remained essentially constant over their full evaporation, but at rates up to 10% higher than for the no radiation case. At higher radiant flux density, the surface-area change with time became progressively more nonlinear, indicating that the radiation had diminished effects on evaporation as the size of the droplets decreased. The drying time for a 50 μm water droplet was an order of magnitude faster when comparing the 106 W/m2 case to the no radiation case. The model was used to estimate the droplet temperature. Between 104 and 5 × 105 W/m2, the droplet temperature changed from being below to above the environment temperature. Thus, the direction of conduction between the droplet and the environment also changed. The proposed model was able to predict the changing evaporation rates for droplets exposed to radiation for ambient conditions varying from dry air to 90% relative humidity.

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