US3769834A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Whole body measurement systems
Assignee: National Aeronautics and Space Administration
•
Filing: 1971-11-18
•
Granted: 1973-11-06
•
Expires: 1991-11-18
Abstract
Abstract A system for measuring the volume and volume variations of a human body under zero gravity conditions is disclosed. An enclosed chamber having a defined volume and arranged for receiving a human body is provided with means for infrasonically varying the volume of the chamber. The changes in volume produce resultant changes in pressure, and under substantially isentropic conditions, an isentropic relationship permits a determination of gas volume which, in turn, when related to total chamber volume permits a determination of the body volume. By comparison techniques, volume changes of a human independent of gravity conditions can be determined.
Inventors
- 👤 J Fletcher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 08:14
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/103; A61B5/107; A61B5/1073; A61B5/08; A61B5/0806; G; G01; G01F; G01F17/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
158 words
A method of ascertaining the volume of a human body wherein a respiratory subject is located within a chamber having a defined volume comprising the steps of cyclically changing at a rate of 1 to 100 Hz the volume of a chamber containing a respiratory subject; suppLying a gas to said respiratory subject; while changing the volume of such chamber, measuring the pressure change in such chamber; measuring the absolute pressure in said chamber; and computing by machine operations the body volume of the respiratory subject by subtracting from the total volume of the enclosure the gas volume as determined from the equation ( Delta P/ Delta V) ( gamma Pg/Vg) where Delta P/ Delta V is the derivative change in pressure relative to volume, gamma is the ratio of specific heat at constant pressure to the specific heat at constant volume, Pg is the absolute pressure of the gas, and Vg is the volume of the gas.
Claim 2
Independent Claim
158 words
A method of ascertaining the volume of a human body wherein a respiratory subject is located within a chamber having a defined volume comprising the steps of cyclically changing at a rate of 1 to 100 Hz the volume of a chamber containing a respiratory subject; suppLying a gas to said respiratory subject; while changing the volume of such chamber, measuring the pressure change in such chamber; measuring the absolute pressure in said chamber; and computing by machine operations the body volume of the respiratory subject by subtracting from the total volume of the enclosure the gas volume as determined from the equation ( Delta P/ Delta V) ( gamma Pg/Vg) where Delta P/ Delta V is the derivative change in pressure relative to volume, gamma is the ratio of specific heat at constant pressure to the specific heat at constant volume, Pg is the absolute pressure of the gas, and Vg is the volume of the gas.
Claim 3
Dependent Claim
37 words
The method as defined in claim 1 wherein the frequency of the changing of the volume is such that it has a short time period relative to the time period established for any leaks from the enclosure.
Claim 4
Dependent Claim
154 words
Apparatus for determining the volume of a human body comprising a substantially gas-tight enclosure containing a gas; means for supplying air to a subject within said enclosure; means for cyclically varying at a rate of 1 to 100 Hz the volume of said enclosure and for deriving an indication of the relative volume of said enclosure; means for deriving indications of changes in pressure; means for deriving an indication of the absolute pressure within said enclosure; means responsive to the derivative change in indications of pressure relative to changes in volume of said enclosure, the ratio of specific heat at constant pressure to the specific heat at constant volume, and the ambient absolute pressure of the gas in said enclosure for deriving the volume of gas in said enclosure; and means responsive to the derived value for the volume of gas in said enclosure for determining the volume of a subject in said enclosure.
Claim 5
Dependent Claim
154 words
Apparatus for determining the volume of a human body comprising a substantially gas-tight enclosure containing a gas; means for supplying air to a subject within said enclosure; means for cyclically varying at a rate of 1 to 100 Hz the volume of said enclosure and for deriving an indication of the relative volume of said enclosure; means for deriving indications of changes in pressure; means for deriving an indication of the absolute pressure within said enclosure; means responsive to the derivative change in indications of pressure relative to changes in volume of said enclosure, the ratio of specific heat at constant pressure to the specific heat at constant volume, and the ambient absolute pressure of the gas in said enclosure for deriving the volume of gas in said enclosure; and means responsive to the derived value for the volume of gas in said enclosure for determining the volume of a subject in said enclosure.
Claim 6
Dependent Claim
32 words
The apparatus of claim 3 wherein said means for varying the volume of said enclosure includes a piston and cylinder system and said pressure deriving means comprises a low frequency response device.
Claim 7
Dependent Claim
82 words
The apparatus of claim 4 wherein said gas volume deriving means operates according to the relationship of ( Delta P/ Delta V) ( gamma P/V) where Delta P/ Delta V is the derivative change in indications of pressure relative to volume in said enclosure, gamma is the ratio of specific heat at constant pressure to the specific heat at constant volume, P is the ambient absolute pressure of the gas in said enclosure, and V is the gas volume in said enclosure.
References Cited (Backward Citations)
DE748729C
Cited
FR1480470A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-05 | 1977-05-07 | 1977-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-05 | 1981-05-07 | 1981-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-05 | 1985-05-07 | 1985-11-06 | $7700.00 | Window Closed / Lapsed |