Improvement of Temperature Precision in Embryo-Incubator Chamber by Reducing Fluctuations

Works of Georgian Technical University ◽

10.36073/1512-0996-2021-2-220-231 ◽

2021 ◽

pp. 220-231

Author(s):

Giorgi Andriadze ◽

◽

Zviad Gurtskaia ◽

Keyword(s):

Heating Element ◽

Infrared Sensor ◽

Control Temperature ◽

Stable Temperature ◽

Reverse Process ◽

Duty Cycles

Temperature is one of the parameters that affects development of embryos. Therefore, it is important to keep stability of temperature in the chambers of embryo-incubators. In modern incubators, some accuracy of temperature has been achieved, although fluctuations are not eliminated yet. The aim of this research was to improve temperature accuracy by reducing of fluctuations. In modern benchtop incubators, a heating element is switched on and automatically shuts off when the desired value is reached. The heating element continues to heat up to a certain temperature after switching off, and the reverse process takes place during cooling. Inappropriate temperature may adversely affect the embryo. To control temperature more precisely, a new principle with infrared sensor has been developed, where power to heater is supplied with different PWM duty cycles. As the results, much more stable temperature with less fluctuations were achieved in comparison to modern systems using thermocouples and thermistors.

Download Full-text

Selective Corrosion of brazed joint between BNi-2 filler metal and stainless steel 316

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100163551 ◽

1996 ◽

Vol 54 ◽

pp. 218-219

Author(s):

H. S. Kim ◽

R. U. Lee

Keyword(s):

Stainless Steel ◽

Filler Metal ◽

Surface Preparation ◽

Optical Microscope ◽

Heating Element ◽

Incomplete Fusion ◽

Atmospheric Conditions ◽

Leak Test ◽

High Temperature Side ◽

Inconel 600

A heating element/electrical conduit assembly used in the Orbiter Maneuvering System failed a leak test during a routine refurbishment inspection. The conduit, approximately 100 mm in length and 12 mm in diameter, was fabricated from two tubes and braze-joined with a sleeve. The tube on the high temperature side (heating element side) and the sleeve were made of Inconel 600 and the other tube was stainless steel (SS) 316. For the filler metal, a Ni-Cr-B brazing alloy per AWS BNi-2, was used. A Helium leak test spotted the leak located at the joint between the sleeve and SS 316 tubing. This joint was dissected, mounted in a plastic mold, polished, and examined with an optical microscope. Debonding of the brazed surfaces was noticed, more pronounced toward the sleeve end which was exposed to uncontrolled atmospheric conditions intermittently. Initially, lack of wetting was suspected, presumably caused by inadequate surface preparation or incomplete fusion of the filler metal. However, this postulation was later discarded based upon the following observations: (1) The angle of wetting between the fillet and tube was small, an indication of adequate wetting, (2) the fillet did not exhibit a globular microstructure which would be an indication of insufficient melting of the filler metal, and (3) debonding was intermittent toward the midsection of the sleeve.

Download Full-text

Acoustic-Reflex Dynamics for Pulsed Signals

Journal of Speech and Hearing Research ◽

10.1044/jshr.2102.295 ◽

1978 ◽

Vol 21 (2) ◽

pp. 295-308

Author(s):

Terry L. Wiley ◽

Raymond S. Karlovich

Keyword(s):

Duty Cycle ◽

Acoustic Impedance ◽

Normal Hearing ◽

Broadband Noise ◽

Threshold Shift ◽

Temporary Threshold Shift ◽

Acoustic Reflex ◽

Stapedius Muscle ◽

Duty Cycles

Contralateral acoustic-reflex measurements were taken for 10 normal-hearing subjects using a pulsed broadband noise as the reflex-activating signal. Acoustic impedance was measured at selected times during the on (response maximum) and off (response minimum) portions of the pulsed activator over a 2-min interval as a function of activator period and duty cycle. Major findings were that response maxima increased as a function of time for longer duty cycles and that response minima increased as a function of time for all duty cycles. It is hypothesized that these findings are attributable to the recovery characteristics of the stapedius muscle. An explanation of portions of the results from previous temporary threshold shift experiments on the basis of acoustic-reflex dynamics is proposed.

Download Full-text