Parthasarathy Vijay Shakkottai

US Patent:

50622951, Nov 5, 1991

Filed:

Dec 24, 1990

Appl. No.:

7/633130

Inventors:

Parthasarathy Shakkottai - Duarte CA
Eug Y. Kwack - Walnut CA

Assignee:

Sparktech - Duarte CA

International Classification:

G01F 2328
G01H 500

US Classification:

73290V

Abstract:

An accurate measurement of liquid levels in a tank are made using a dual tube sonic level gage. This uses plane waves of sound, in air, propagated in two vertical tubular wave guides to locate the levels of liquid contained in each tube. One tube has slots at the bottom and allows both the light (upper) and the heavy (lower) liquids to be present inside the tube at the same level as outside (i. e. in the tank). The other tube allows only the lower liquid to enter it. In the application for a measurement of gasoline and water levels in a tank, levels outside the tube (i. e. in the tank) are calculated using the equations of hydrostatics. Corrections due to temperature need not be made in order to obtain levels accurate to 1 percent.

US Patent:

48768898, Oct 31, 1989

Filed:

Jul 5, 1988

Appl. No.:

7/215374

Inventors:

Parthasarathy Shakkottai - Duarte CA
Eug Y. Kwack - Walnut CA
Shakkottai P. Venkate-Shan - Gandhi Nagar, Adyar Madras, IN

International Classification:

G01W 102
G01N 2902

US Classification:

733365

Abstract:

The water vapor content for air in drier ducts, ovens, furnaces and the like is determined by a measurement of sound speed which is done by measuring the time difference between sound pulses reflected by two reflectors spaced a known distance apart in a guide tube. The transmitter-receiver is located at one end of the tube. The tube has enough number of holes to allow the hot moist air to get into the probe tube. A non-porous tube containing dry air placed in the same duct provides a similar measurement of dry-sound speed. The ratio of the two speeds of sound or the two measured time intervals is a simple function of the water vapor content practically independent of temperature thereby providing a very accurate measurement of water vapor content over an extremely wide range of temperatures. The sensor is accurate, immune to harsh environments, has an extremely low time constant, has absolutely no hysteresis and needs no calibration.

US Patent:

48965405, Jan 30, 1990

Filed:

Apr 8, 1988

Appl. No.:

7/179076

Inventors:

Parthasarathy Shakkottai - Duarte CA
Eug Y. Kwack - Walnut CA

International Classification:

G01F 186
G01F 1504

US Classification:

7386102

Abstract:

The flowmeter is based on a measurement of phase difference between two points on the circumference of a pipe separated axially by an integral multiple of sound wavelength. Plane sound waves are generated aeroacoustically by a non-protruding ring cavity energized either directly by the flow or by a subsidiary flow of the same medium. The frequency of the aeroacoustic source varies with temperature and therefore the temperature can be obtained. In the case of steam flow, temperature can be measured independently and therefore from the measured frequency (or speed of sound), the quality of wet steam can be measured. The flowmeter is linear in velocity and no calibrations are required.

US Patent:

47624256, Aug 9, 1988

Filed:

Oct 15, 1987

Appl. No.:

7/108813

Inventors:

Parthasarathy Shakkottai - Duarte CA
Shakkottai P. Venkateshan - Gandhi Nagar, Adyar, Madras 60020, IN

International Classification:

G01K 1122

US Classification:

374117

Abstract:

Measurements of the times of flight of sound waves can be used to determine temperature in a gas contained in a long tube which confines sound waves. Sound pulses are transmitted and received by a suitable loud speaker attached to one end of the long tube. A number of stubs or other discontinuities produce the sound reflections whose times of arrival are measured. The time intervals yield average sound speeds in each interval between any two stubs from which temperatures are calculated. Corrections for thermal expansion of the tube are easily made.

US Patent:

50028944, Mar 26, 1991

Filed:

Jun 6, 1988

Appl. No.:

7/202401

Inventors:

Parthasarathy Shakkottai - Duarte CA
Eug Y. Kwack - Walnut CA
Daniel D. Lawson - Arcadia CA

International Classification:

G01N 3346

US Classification:

436128

Abstract:

The lignin content of wood, paper pulp or other material containing lignin (such as filter paper soaked in black liquor) is more readily determined by flash pyrolysis of the sample at approximately 550. degree. C. in a reducing atmosphere of hydrogen or in an inert atmosphere of helium followed by a rapid analysis of the product gas by a mass spectrometer. The heated pyrolysis unit as fabricated comprises a small platinum cup welded to an electrically-heated stainless steel ribbon with control means for programmed short duration (1. 5 sec, approximately) heating and means for continuous flow of hydrogen or helium. The pyrolysis products enter an electron-ionization mode mass spectrometer for spectral evaluation. Lignin content is obtained from certain ratios of integrated ion currents of many mass spectral lines, the ratios being linearly related to the Kappa number of Klason lignin.

US Patent:

49798200, Dec 25, 1990

Filed:

Apr 24, 1989

Appl. No.:

7/341840

Inventors:

Parthasarathy Shakkottai - Duarte CA
Vijayaraghavan Alwar - Altadena CA

International Classification:

G01M 324

US Classification:

356129

Abstract:

Two laser beams derived from a laser pass through a furnace and are superposed in a laser spot to produce interference fringes having the same pitch as that of a Ronchi grating printed on a retroreflecting screen. Minute fluctuations of the laser beams caused by sound waves from leaks result in intensity fluctuations of the laser spot when the laser fringes move past the fixed grating. A telescope and photocell arrangement detects the light variations to produce an electrical signal which is amplified and filtered to detect the sound of leaks. This non-contact laser Schlieren microphone is sensitive to sounds all along the path of the beams.

US Patent:

52110524, May 18, 1993

Filed:

Oct 11, 1990

Appl. No.:

7/598017

Inventors:

Parthasarathy Shakkottai - Duarte CA
Eug Y. Kwack - Walnut CA

Assignee:

Sparktech - Duarte CA

International Classification:

G01N 3700

US Classification:

73 232

Abstract:

The composition monitor uses a flow driven acoustic resonator whose frequency is simply related to the speed of sound of the gaseous mixture present in the cavity resonator. Because the speed of sound is a function of temperature and composition of mixtures, the oscillator frequency signal may be used to measure the composition and control the process. The aeroacoustic sources have the advantage that they are immune to high pressure and high temperature and are energized by flows leading into or out of reactors. In addition, sound is led to a measurement microphone from the source by a solid rod which isolates it from high pressure and temperature obtaining thereby a robust sensor.

US Patent:

51598434, Nov 3, 1992

Filed:

Feb 19, 1991

Appl. No.:

7/658477

Inventors:

Parthasarathy Shakkottai - Duarte CA
Eug Y. Kwack - Walnut CA
Lloyd Back - La Canada CA

Assignee:

The United States of America as represented by the Administrator of the
National Aeronautics and Space Administration - Washington DC

International Classification:

G01N 2900
G01N 2922

US Classification:

73 2405

Abstract:

Density measurements can be made in a gas contained in a flow through enclosure by measuring the sound pressure level at a receiver or microphone located near a dipole sound source which is driven at constant velocity amplitude at low frequencies. Analytical results, which are provided in terms of geometrical parameters, wave numbers and sound source type for systems of this invention, agree well with published data. The relatively simple designs feature a transmitter transducer at the closed end of a small tube and a receiver transducer on the circumference of the small tube located a small distance away from the transmitter. The transmitter should be a dipole operated at low frequency with the kL value preferably less than about 0. 3.