P6.09 MULTIPLE REFLECTIONS, NOT A SINGLE DISTAL AORTIC REFLECTION DETERMINE PRESSURE WAVE SHAPE

2013 ◽  
Vol 7 (3-4) ◽  
pp. 156
Author(s):  
N. Westerhof ◽  
B.E. Westerhof
Keyword(s):  
Pressure Wave ◽  
Wave Shape ◽  
Multiple Reflections

Controlling the Tonal Characteristics of the Aerodynamic Noise Generated by Fan Rotors

1970 ◽  
Vol 92 (1) ◽  
pp. 143-154 ◽  
Author(s):  
R. C. Mellin ◽  
G. Sovran
Keyword(s):  
Background Noise ◽  
Pressure Wave ◽  
Sound Pressure ◽  
Axial Flow ◽  
Aerodynamic Noise ◽  
Wave Shape ◽  
Survey Technique ◽  
The Individual ◽  
Equal Spacing

A technique has been developed for selecting circumferentially-unequal blade spacings that will reduce the tonal annoyance of the aerodynamic noise generated by the rotors of fans. The procedure has been successfully applied to a number of axial-flow fans. The predictions of harmonic spectra are based on an experimentally-determined sound-pressure wave shape for the individual blades of such fans. However, the technique can be extended to other types of tonal-annoyance problems provided that the particular relevant sound-pressure wave shape is determined. Unequal blade spacings that will produce a particular degree of “whiteness” in the noise with a minimum departure from equal spacing are tabulated for a range of blade numbers. Both unbalanced and naturally balanced blading arrangements are considered. A survey technique is also outlined for those applications in which it is important to reduce a particular frequency, or where blending with a given background noise must be achieved.

REFLECTIONS FROM MULTIPLE TRANSITION LAYERS PART I—THEORETICAL RESULTS

Geophysics ◽  
1958 ◽  
Vol 23 (2) ◽  
pp. 223-243 ◽  
Author(s):  
L. H. Berryman ◽  
P. L. Goupillaud ◽  
K. H. Waters
Keyword(s):  
Digital Computer ◽  
Input Pulse ◽  
Double Layers ◽  
Wave Shape ◽  
Multiple Reflections ◽  
Base Thickness ◽  
Transition Layers ◽  
Double Transition ◽  
Theoretical Results ◽  
Input Wave

Continuous velocity logs may be approximated by a series of zones in which the velocity is a linear function of the depth. The reflection response of a series of transition layers may be calculated from an iterative type formula, developed in this paper, which is well suited to digital computer use. This solution takes into account multiple reflections between layers. The reflection output for any input wave shape may be calculated. In this paper a Gram Charlier series pulse having a spectrum peaked at 40 cps is used throughout to facilitate comparison of results. The dependence of the reflection response of single and double layers on frequency and the reflections for the standard input pulse are illustrated. It is shown that 1. Symmetrical double transition layers give an appreciable reflection output even for a base thickness as low as 10 ft. 2. The upper layers of a multilayer group may influence considerably the reflection character from the lower layers.

The Impact of Light Polarisation on Light Field of Scenes with Multiple Reflections

2020 ◽  
pp. 108-115 ◽  
Author(s):  
Vladimir P. Budak ◽  
Anton V. Grimaylo
Keyword(s):  
Mathematical Model ◽  
Light Field ◽  
Global Illumination ◽  
Multiple Reflections ◽  
Software Environment ◽  
The Monte Carlo Method ◽  
Mueller Matrices ◽  
Volume Integration ◽  
The Impact

The article describes the role of polarisation in calculation of multiple reflections. A mathematical model of multiple reflections based on the Stokes vector for beam description and Mueller matrices for description of surface properties is presented. On the basis of this model, the global illumination equation is generalised for the polarisation case and is resolved into volume integration. This allows us to obtain an expression for the Monte Carlo method local estimates and to use them for evaluation of light distribution in the scene with consideration of polarisation. The obtained mathematical model was implemented in the software environment using the example of a scene with its surfaces having both diffuse and regular components of reflection. The results presented in the article show that the calculation difference may reach 30 % when polarisation is taken into consideration as compared to standard modelling.

Microwave Non-Destructive Testing of Coatings and Paints Using Free Space Microwave Measurement

2005 ◽  
Vol 2 (2) ◽  
pp. 17
Author(s):  
Norhayati Hamzah ◽  
Deepak Kumar Ghodgaonkar ◽  
Kamal Faizin Che Kasim ◽  
Zaiki Awang
Keyword(s):  
Free Space ◽  
Protective Coatings ◽  
Microwave Measurement ◽  
Multiple Reflections ◽  
Destructive Testing ◽  
Lens Antennas ◽  
Coatings And Paints ◽  
Microwave Nondestructive Testing ◽  
Mode Transitions ◽  
Diffraction Effects

Microwave nondestructive testing (MNDT) techniques are applied to evaluate quality of anti-corrosive protective coatings and paints on metal surfaces. A tree-space microwave measurement (FSMM) system is used for MNDT of protective coatings. The FSMM system consists of transmit and receive spot-focusing horn lens antennas, a vector network analyzer, mode transitions and a computer. Diffraction effects at the edges of the sample are minimized by using spot-focusing horn lens antennas. Errors due to multiple reflections between antennas are corrected by using free-space LRL (line, reflect, line) calibration technique. We have measured complex reflection coefficient of polyurethane based paint which is coated on brass plates.

Numerical and experimental investigation on internal membrane pressure wave inside sealed structure

2013 ◽  
Vol 61 (3) ◽  
pp. 613-621 ◽  
Author(s):  
W. Barnat
Keyword(s):  
Experimental Investigation ◽  
Pressure Wave ◽  
Pressure Increase ◽  
Internal Organs ◽  
Pressure Impulse ◽  
Internal Membrane ◽  
Contaminated Area

Abstract The article presents an approach to modeling the internal membrane pressure wave inside a sealed structure. During an explosion near a vehicle when a pressure wave reaches a hull, a pressure wave inside arises due to the hull’s bottom and the deformation of sides. They act like the piston - membrane. This membrane transfers the pressure impulse into the vehicle’s interior. A pressure increase causes the damage of internal organs or even death of occupants. In case of an armor penetration the pressure increase may be even larger. One of basic methods to protect a crew is to open hatches. However, such a method cannot be used in a contaminated area.

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