scholarly journals Using POD method in experiments with convection flow on the cube benchmark

2019 ◽  
Vol 213 ◽  
pp. 02071
Author(s):  
Daniil Sergeev ◽  
Alexander Kandaurov
Keyword(s):  
Low Cost ◽  
Velocity Fields ◽  
Measuring System ◽  
Convection Flow ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Continuous Laser ◽  
Frequency Spectra ◽  
Ansys Cfx ◽  
Good Agreement

Investigations of the flow structure on the benchmark “cube” under conditions of natural convection caused by a vertical temperature gradient are performed using a low cost PIV-measuring system with continuous laser. The obtained velocity fields were processed with POD method to obtain typical structures (modes) in the flow. It is shown that the steady flow can be described by combination of the first three modes. It is demonstrated that only starting with the third mode there is a significant change in the spectra of the amplitude coefficients of the modes, the peak shifts to the region of higher frequencies. Thus accounting for this mode is essential for describing turbulent processes in the system and verification of numerical calculations. Comparison with the results of the LES simulation performed using the Ansys CFX package (taking into account the results of processing the experimental data by the POD method) demonstrated good agreement both in the structure of the modes and in their frequency spectra.

scholarly journals Effects of rotation on the bulk turbulent convection

2019 ◽  
Vol 881 ◽  
pp. 648-659
Author(s):  
Francesco Toselli ◽  
Stefano Musacchio ◽  
Guido Boffetta
Keyword(s):  
Reynolds Numbers ◽  
Boussinesq Approximation ◽  
Velocity Fields ◽  
Turbulent Convection ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Maximum Enhancement ◽  
Prandtl Numbers ◽  
Effects Of Rotation ◽  
Rayleigh Benard

We study rotating homogeneous turbulent convection forced by a mean vertical temperature gradient by means of direct numerical simulations in the Boussinesq approximation in a rotating frame. In the absence of rotation, our results are in agreement with the ‘ultimate regime of thermal convection’ for the scaling of the Nusselt and Reynolds numbers versus Rayleigh and Prandtl numbers. Rotation is found to increase both $Nu$ and $Re$ at fixed $Ra$ with a maximum enhancement for intermediate values of the Rossby numbers, qualitatively similar, but with stronger intensity, to what is observed in Rayleigh–Bénard rotating convection. Our results are interpreted in terms of a quasi-bidimensionalization of the flow with the formation of columnar structures displaying strong correlation between the temperature and the vertical velocity fields.

A LOW-COST RESISTIVIMETER FOR USE IN PRACTICAL LECTURES OF APPLIED GEOPHYSICS

2016 ◽  
Vol 34 (1) ◽  
Author(s):  
Walter Sydney Dutra Folly ◽  
Aracy Sousa Senra
Keyword(s):  
Electrical Resistivity ◽  
Low Cost ◽  
Test Area ◽  
Vertical Electrical Sounding ◽  
Applied Geophysics ◽  
Resistivity Profile ◽  
Electrical Sounding ◽  
Good Agreement

ABSTRACT. We describe the construction and testing of a simple and efficient low-cost resistivimeter designed for use in practical classes in Applied Geophysics. The equipment was successfully tested in a vertical electrical sounding (VES) performed on sandy terrain within the campus of the Universidade Federal de Sergipe, Brazil. The VES results were in good agreement with the profiles obtained from two boreholes located approximately 500 m from the test area, clearly demonstrating the efficiency of the equipment and the adopted methodology.Keywords: vertical electrical sounding, electrical resistivity, resistivity profile. RESUMO. Neste artigo, descrevemos a construção e o teste de um resistivímetro de baixo custo, simples e eficiente, concebido para ser utilizado em aulas práticas de Geofísica Aplicada. O equipamento foi testado com a realização de uma sondagem elétrica vertical (SEV) em um terreno arenoso localizado no campus da Universidade Federal de Sergipe, Brasil. Os resultados obtidos nesta SEV apresentaram boa concordância com os perfis observados em dois poços de sondagem localizados a 500 m da área de teste, fato que comprovou a eficiência do equipamento e da metodologia adotada.Palavras-chave: sondagem elétrica vertical, resistividade elétrica, perfil de resistividade. 

scholarly journals The grades and freshness assessment of eggs based on density detection using machine vision and weighing sensor

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Supakorn Harnsoongnoen ◽  
Nuananong Jaroensuk
Keyword(s):  
Machine Vision ◽  
Vision System ◽  
Low Cost ◽  
Measuring System ◽  
Coefficient Of Determination ◽  
Water Displacement ◽  
Non Invasive ◽  
Future Potential ◽  
Non Destructive ◽  
Egg Freshness

AbstractThe water displacement and flotation are two of the most accurate and rapid methods for grading and assessing freshness of agricultural products based on density determination. However, these techniques are still not suitable for use in agricultural inspections of products such as eggs that absorb water which can be considered intrusive or destructive and can affect the result of measurements. Here we present a novel proposal for a method of non-destructive, non-invasive, low cost, simple and real—time monitoring of the grading and freshness assessment of eggs based on density detection using machine vision and a weighing sensor. This is the first proposal that divides egg freshness into intervals through density measurements. The machine vision system was developed for the measurement of external physical characteristics (length and breadth) of eggs for evaluating their volume. The weighing system was developed for the measurement of the weight of the egg. Egg weight and volume were used to calculate density for grading and egg freshness assessment. The proposed system could measure the weight, volume and density with an accuracy of 99.88%, 98.26% and 99.02%, respectively. The results showed that the weight and freshness of eggs stored at room temperature decreased with storage time. The relationship between density and percentage of freshness was linear for the all sizes of eggs, the coefficient of determination (R2) of 0.9982, 0.9999, 0.9996, 0.9996 and 0.9994 for classified egg size classified 0, 1, 2, 3 and 4, respectively. This study shows that egg freshness can be determined through density without using water to test for water displacement or egg flotation which has future potential as a measuring system important for the poultry industry.

scholarly journals Thermal ignition of a combustible over an inclined hot plate

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Salaika Parvin ◽  
Nepal Chandra Roy ◽  
Rama Subba Reddy Gorla
Keyword(s):  
Mixed Convection ◽  
Convection Flow ◽  
Physical Parameters ◽  
Thermal Ignition ◽  
Mixed Convection Flow ◽  
Flow Properties ◽  
Continuous Transformation ◽  
Hot Plate ◽  
Ignition Characteristics ◽  
Good Agreement

AbstractIn this study, the ignition characteristics and the flow properties of the mixed convection flow are presented. Detailed formulations of the forced, natural and mixed convection problems have been discussed. In order to avoid inconvenient switch between the forced and natural convection we introduce a continuous transformation in the mixed convection. We make a comparison between these situations which reveal a good agreement. For mixed convection flow, the ignition distance is explicitly expressed as a function of the Prandtl number, reaction parameter and wall temperature. It has been observed that owing to the increase of the aforesaid parameters, the thermal ignition distance is reduced. Numerical results are illustrated for velocity, temperature, and concentration for different physical parameters. Furthermore, the development of combustion is presented by using streamlines, isotherms and isolines of fuel and oxidizer.

Dependence of Aerosol Particle Concentration in Surface Air over the Moscow Region on Wind Speed and Lapse Rate

2021 ◽  
pp. 103-110
Author(s):  
E. A. Stulov ◽  
◽  
E. V. Sosnikova ◽  
N. A. Monakhova ◽  
◽  
...  
Keyword(s):  
Surface Layer ◽  
Wind Speed ◽  
Particle Concentration ◽  
Meteorological Factors ◽  
Lapse Rate ◽  
Radiosonde Data ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Simple Estimation ◽  
The City

Based on the daily measurements of atmospheric aerosol characteristics in the city of Dolgoprudny (20 km from the center of Moscow) carried out during 2013-2018, the influence of some meteorological factors on the concentration of various aerosol fractions in the surface layer of the atmosphere is analyzed. It is that the aerosol concentration depends most on the wind speed and the vertical temperature gradient. The method of simple estimation of aerosol particles accumulation conditions in the surface layer based on the use of standard radiosonde data is developed.

Experimental Study on New Wave Measurement Using Passive Underwater Acoustics

2008 ◽  
Author(s):  
Jing Li ◽  
Dingyong Yu ◽  
Huaxing Liu
Keyword(s):  
Virtual Instrument ◽  
Low Cost ◽  
Measuring System ◽  
Time Data ◽  
Significant Wave ◽  
Wave Measurement ◽  
Wave Heights ◽  
Mean Wave Period ◽  
Passive Acoustic ◽  
User Friendly

The passive acoustic-based wave measurement via hydrophones is presented in this paper. It has the potential to measure non-intrusively, implement with low cost and with higher resolution. Details of experiments, real-time data recording and processing are described respectively. Particularly, the portable data acquisition system based on virtual instrument technique is designed to make the in situ measurement convenient and user-friendly. Special emphasis is put on FFT filtering technique to band pass the signal fast and efficiently. The key wave parameters, i.e. the mean wave period and the significant wave height, can be obtained from the comparatively safe and stable underwater by means of submerged hydrophones. Considering the pressure sensor has been widely used in the ocean wave measurement, it is deployed simultaneously to test the feasibility of the new system. The result shows that the present measuring system can give satisfactory measurement of significant wave heights and average wave periods in shallow water despite of the little deviation.

scholarly journals Robot Control Using Alternative Trajectories Based on Inverse Errors in the Workspace

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Quoc Khanh Duong ◽  
Thanh Trung Trang ◽  
Thanh Long Pham
Keyword(s):  
Control System ◽  
High Resolution ◽  
Robot Control ◽  
Low Cost ◽  
Transmission System ◽  
Measuring System ◽  
Robot Calibration ◽  
Measuring Device ◽  
Calibration Solution ◽  
System Errors

It is easy to realize that most robots do not move to the desired endpoint (Tool Center Point (TCP)) using high-resolution noncontact instrumentation because of manufacturing and assembly errors, transmission system errors, and mechanical wear. This paper presents a robot calibration solution by changing the endpoint trajectories while maintaining the robot’s control system and device usages. Two independent systems to measure the endpoint positions, the robot encoder and a noncontact measuring system with a high-resolution camera, are used to determine the endpoint errors. A new trajectory based on the measured errors will be built to replace the original trajectory. The results show that the proposed method can significantly reduce errors; moreover, this is a low-cost solution and easy to apply in practice and calibration can be done cyclically. The only requirement for this method is a noncontact measuring device with high-resolution and located independently with the robot in calibration.

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