scholarly journals General post-Minkowskian expansion of time transfer functions

2008 ◽  
Vol 25 (14) ◽  
pp. 145020 ◽  
Author(s):  
Pierre Teyssandier ◽  
Christophe Le Poncin-Lafitte
Keyword(s):  
Transfer Functions ◽  
Time Transfer

Experimental Investigation about Rinse Water Consumption of a CIP Process Applied to a Shell and Tube Exchanger

2013 ◽  
Vol 785-786 ◽  
pp. 1294-1298
Author(s):  
Valdir Melero ◽  
Estevao Dos Santos Gedraite ◽  
Leo Kunigk ◽  
Patricia Angelica Vieira ◽  
Ricardo Amâncio Malagoni ◽  
...  
Keyword(s):  
Food Industry ◽  
Dead Time ◽  
Transfer Functions ◽  
Water Flow Rate ◽  
Systems Dynamics ◽  
Temperature Influence ◽  
Time Transfer ◽  
Flow Models ◽  
Shell And Tube ◽  
Rinse Water

This paper focused the CIP (clean in place) rinse stage, typically applied to the food industry. The dynamic behavior of residuals removal kinetics was studied, to obtain mathematical models that describe adequately the system. The optimization of water, detergent, etc., is the next goal. The obtained results show that the temperature influence can be neglected in comparison with the rinse water flow rate considering the cleaning process. The systems dynamics are non linear and were adequately represented by 1st order plus dead time transfer functions. The flow models obtained with this paper were validated versus experimental data and the results were close with respect to the last ones.

scholarly journals Relativistic modeling of atmospheric occultations with time transfer functions

2021 ◽  
Vol 648 ◽  
pp. A46
Author(s):  
A. Bourgoin ◽  
M. Zannoni ◽  
L. Gomez Casajus ◽  
P. Tortora ◽  
P. Teyssandier
Keyword(s):  
Transfer Function ◽  
Transfer Functions ◽  
Integral Form ◽  
Original Method ◽  
Electromagnetic Signal ◽  
Time Transfer ◽  
Spacetime Curvature ◽  
Covariant Description ◽  
Analytical Expressions ◽  
Optical Metric

Context. Occultation experiments represent unique opportunities to remotely probe the physical properties of atmospheres. The data processing involved in modeling the time and frequency transfers of an electromagnetic signal requires that refractivity be properly accounted for. On theoretical grounds, little work has been done concerning the elaboration of a covariant approach for modeling occultation data. Aims. We present an original method allowing fully analytical expressions to be derived up to the appropriate order for the covariant description of time and frequency transfers during an atmospheric occultation experiment. Methods. We make use of two independent powerful relativistic theoretical tools, namely the optical metric and the time transfer functions formalism. The former allows us to consider refractivity as spacetime curvature while the latter is used to determine the time and frequency transfers occurring in a curved spacetime. Results. We provide the integral form of the time transfer function up to any post-Minkowskian order. The discussion focuses on the stationary optical metric describing an occultation by a steadily rotating and spherically symmetric atmosphere. Explicit analytical expressions for the time and frequency transfers are provided at the first post-Minkowskian order and their accuracy is assessed by comparing them to results of a numerical integration of the equations for optical rays. Conclusions. The method accurately describes vertical temperature gradients and properly accounts for the light-dragging effect due to the motion of the optical medium. It can be pushed further in order to derive the explicit form of the time transfer function at higher order and beyond the spherical symmetry assumption.

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