scholarly journals Some aspects of thermal diffusivity for various soil layers in different harmonics

MAUSAM ◽  
2021 ◽  
Vol 49 (2) ◽  
pp. 255-258
Author(s):  
B. S. LAMBA ◽  
SUNITA BHANDARI
Keyword(s):  
Thermal Diffusivity ◽  
Amplitude Ratio ◽  
Phase Lag ◽  
Soil Medium ◽  
Soil Layers ◽  
Annual Cycles ◽  
Third Harmonic ◽  
The Third ◽  
Experimental Values ◽  
Dry Farming

Values of thermal diffusivity (K) in different soil layers for the first three harmonics have been computed for six stations in the dry farming tract of India by using amplitude ratio and phase lag. In general, the combined effect of all these harmonics gives the values of K close to the order of the experimental values. It is found that the theory of simple heat conduction is not applicable to soil medium. While the lowest values of K in all the harmonics are found at Rajahmundry, the highest values are observed at either Hissar or Bhubaneshwar for the first two harmonics and at Pantnagar for the third harmonic. Strong annual and bi-annual cycles dominate at Hissar. Pantnagar and Bhubaneshwar while quarterly cycle is significant only at Pantnagar.  

scholarly journals Soil thermal diffusivity estimated from data of soil temperature and single soil component properties

2013 ◽  
Vol 37 (1) ◽  
pp. 106-112 ◽  
Author(s):  
Quirijn de Jong van Lier ◽  
Angelica Durigon
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Soil Temperature ◽  
Spatial Organization ◽  
Amplitude Ratio ◽  
Subsurface Layer ◽  
Phase Lag ◽  
Soil Thermal Diffusivity ◽  
Soil Component ◽  
Soil Components

Under field conditions, thermal diffusivity can be estimated from soil temperature data but also from the properties of soil components together with their spatial organization. We aimed to determine soil thermal diffusivity from half-hourly temperature measurements in a Rhodic Kanhapludalf, using three calculation procedures (the amplitude ratio, phase lag and Seemann procedures), as well as from soil component properties, for a comparison of procedures and methods. To determine thermal conductivity for short wave periods (one day), the phase lag method was more reliable than the amplitude ratio or the Seemann method, especially in deeper layers, where temperature variations are small. The phase lag method resulted in coherent values of thermal diffusivity. The method using properties of single soil components with the values of thermal conductivity for sandstone and kaolinite resulted in thermal diffusivity values of the same order. In the observed water content range (0.26-0.34 m³ m-3), the average thermal diffusivity was 0.034 m² d-1 in the top layer (0.05-0.15 m) and 0.027 m² d-1 in the subsurface layer (0.15-0.30 m).

The Bender Equation of State and Virial Coefficients

2000 ◽  
Vol 65 (9) ◽  
pp. 1464-1470 ◽  
Author(s):  
Anatol Malijevský ◽  
Tomáš Hujo
Keyword(s):  
Equation Of State ◽  
Virial Coefficient ◽  
Virial Coefficients ◽  
Low Density ◽  
Second Virial Coefficients ◽  
The Third ◽  
Temperature Dependences ◽  
Experimental Values

The second and third virial coefficients calculated from the Bender equation of state (BEOS) are tested against experimental virial coefficient data. It is shown that the temperature dependences of the second and third virial coefficients as predicted by the BEOS are sufficiently accurate. We conclude that experimental second virial coefficients should be used to determine independently five of twenty constants of the Bender equation. This would improve the performance of the equation in a region of low-density gas, and also suppress correlations among the BEOS constants, which is even more important. The third virial coefficients cannot be used for the same purpose because of large uncertainties in their experimental values.

scholarly journals Ultrafast Third-Order Nonlinear Optical Response Excited by fs Laser Pulses at 1550 nm in GaN Crystals

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3194
Author(s):  
Adrian Petris ◽  
Petronela Gheorghe ◽  
Tudor Braniste ◽  
Ion Tiginyanu
Keyword(s):  
Harmonic Generation ◽  
Nonlinear Optical ◽  
Laser Pulses ◽  
Third Harmonic Generation ◽  
High Repetition Rate ◽  
Third Order ◽  
Third Harmonic ◽  
The Third ◽  
High Repetition ◽  
Gan Crystal

The ultrafast third-order optical nonlinearity of c-plane GaN crystal, excited by ultrashort (fs) high-repetition-rate laser pulses at 1550 nm, wavelength important for optical communications, is investigated for the first time by optical third-harmonic generation in non-phase-matching conditions. As the thermo-optic effect that can arise in the sample by cumulative thermal effects induced by high-repetition-rate laser pulses cannot be responsible for the third-harmonic generation, the ultrafast nonlinear optical effect of solely electronic origin is the only one involved in this process. The third-order nonlinear optical susceptibility of GaN crystal responsible for the third-harmonic generation process, an important indicative parameter for the potential use of this material in ultrafast photonic functionalities, is determined.

The third harmonic generated voltage by salient-pole synchronous generator during 3-phase-to-ground fault

2017 ◽  
Vol 27 (11) ◽  
pp. e2401
Author(s):  
Nur Iylia Shah Riman ◽  
Mohd Faris Abdullah ◽  
Mohd Fakhizan Romlie ◽  
Zuhairi Baharudin
Keyword(s):  
Synchronous Generator ◽  
Third Harmonic ◽  
The Third ◽  
Ground Fault ◽  
Salient Pole

scholarly journals Third harmonic current injection into highly saturated multi-phase machines

2017 ◽  
Vol 66 (1) ◽  
pp. 179-187
Author(s):  
Felix Klute ◽  
Torben Jonsky
Keyword(s):  
Current Injection ◽  
Saturation Level ◽  
Permanent Magnet Synchronous Machines ◽  
Flux Linkage ◽  
Harmonic Current ◽  
Fem Model ◽  
Third Harmonic ◽  
The Third ◽  
Rotor Flux ◽  
Multi Phase

Abstract One advantage of multi-phase machines is the possibility to use the third harmonic of the rotor flux for additional torque generation. This effect can be maximised for Permanent Magnet Synchronous Machines (PMSM) with a high third harmonic content in the magnet flux. This paper discusses the effects of third harmonic current injection (THCI) on a five-phase PMSM with a conventional magnet shape depending on saturation. The effects of THCI in five-phase machines are shown in a 2D FEM model in Ansys Maxwell verified by measurement results. The results of the FEM model are analytically analysed using the Park model. It is shown in simulation and measurement that the torque improvement by THCI increases significantly with the saturation level, as the amplitude of the third harmonic flux linkage increases with the saturation level but the phase shift of the rotor flux linkage has to be considered. This paper gives a detailed analysis of saturation mechanisms of PMSM, which can be used for optimizing the efficiency in operating points of high saturations, without using special magnet shapes.

Imaging Cracks in Bones Using Acoustic Nonlinearity: A Simulation Study

2011 ◽  
Vol 97 (5) ◽  
pp. 728-733
Author(s):  
Yang Liu ◽  
Xiasheng Guo ◽  
Zhao Da ◽  
Dong Zhang ◽  
Xiufen Gong
Keyword(s):  
Time Reversal ◽  
Three Dimensional ◽  
Harmonic Component ◽  
Ultrasonic Signal ◽  
Long Bone ◽  
Third Harmonic ◽  
Acoustic Nonlinearity ◽  
The Third ◽  
Nonlinear Approach ◽  
Radial Depth

This article proposes an acoustic nonlinear approach combined with the time reversal technique to image cracks in long bones. In this method, the scattered ultrasound generated from the crack is recorded, and the third harmonic nonlinear component of the ultrasonic signal is used to reconstruct an image of the crack by the time reversal process. Numerical simulations are performed to examine the validity of this approach. The fatigue long bone is modeled as a hollow cylinder with a crack of 1, 0.1, and 0.225 mm in axial, radial and circumferential directions respectively. A broadband 500 kHz ultrasonic signal is used as the exciting signal, and the extended three-dimensional Preisach-Mayergoyz model is used to describe the nonclassical nonlinear dynamics of the crack. Time reversal is carried out by using the filtered third harmonic component. The localization capability depends on the radial depth of the crack.

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