A thermistor based sensor for flow measurement in water

There is limited experimental data describing the mixing processes and coherent velocity structures near the surface of the ocean. These play an important part in the interactions between the atmosphere and the ocean and thus affect the climate of the earth. A robust, low cost thermistor based sensor suitable for use in the detection and quantification of velocity structures has been designed and developed. The flow sensor, a thermal anemometer, consists of a self-heated thermistor that is maintained at constant temperature using a feedback control circuit. The thermistor is exposed to the moving fluid and the heat transfer from it is a function of the velocity of the fluid. The sensor has been interfaced with a PC to facilitate data acquisition. A tow tank calibration and testing facility also interfaced to a PC was developed. The sensor is compensated for changes in ambient fluid temperature, which is a major problem for all thermal anemometers that operate in water. The calibration relation that is normally used for thermistor anemometers has been improved upon and gives better results than any found in the literature. In order to provide electrical isolation from the water the sensor was protected with an insulating coating. The effect of coating thickness and the type of coating used on sensor performance was investigated. It was found that a polymer coating resulted in a sensor that did not show any appreciable drift due to sensor contamination over a number of months. This is a significant improvement over glass coated hot film sensors, which are widely used for velocity measurements in water and previously developed thermistor based sensors. The effect of various control circuit parameters on the frequency response of the sensor was determined and these parameters were tuned to give maximum frequency response A procedure for easily replacing broken/damaged sensors in the field was also developed

Development of enhanced performance luminescence-based optical sensor systems for single-analyte and multii-analyte applications

Luminescence-based sensors are widely used and are the subject of considerable attention from both a research and a commercial perspective. This work details the development of enhanced-performance luminescence-based sensor systems. Development eorts have focussed on three areas: instrumentation electronics, en- hanced luminescence capture-based optical platforms, and multi-parameter sens- ing using numerical techniques. Three instrumentation electronics systems were developed using a progressive design process that culminated in the development of a DSP-based system which is capable of multi-frequency operation and can be used to obtain intensity, phase or ratiometric-intensity measurements. When a luminophore is placed close to a dielectric interface it exhibits an anisotropic emission prole. An optical probe that exploits this phenomenon to achieve enhanced luminescence capture was designed previously, however, it suered from a number of shortcomings. A range of design improvements were developed and implemented which addressed a number of robustness and reliabil- ity related issues and which facilitated ratiometric mode operation. In addition, an enhanced capture element that was optimised for general sensing as opposed to bio-sensing applications was designed using a combined ray tracing/optimisation approach. The detection of multiple parameters using a single luminescent sensor ele- ment is desirable in many applications. A multi-parameter technique was devel- oped that achieves this through the use of numerical techniques. This approach addresses a number of limitations that are associated with alternative techniques. A key part of this work was the development of sensor systems for a number of specic applications. Sensor systems were developed for the following: real-time measurement of oxygen concentration in breath, measurement of dissolved oxygen and dissolved carbon dioxide, and the simultaneous measurement of oxygen and temperature using a single sensor element

The Dalles and Hood River Formations, and the Columbia River Gorge

A definite assignment of geologic dates to the main events of the Cenozoic history of the Columbia Gorge and Columbia plateau-vulcanism, sedimentation, folding, erosion-is manifestly possible only if we know the age of at least some of the formations. Because of their stratigraphic position, the ages of The Dalles beds and of the gravels heretofore known as Satsop lying between the Columbia River lavas and the volcanic Cascades formation in the Gorge have critical value for historical purposes. Some doubt has arisen in recent years regarding the extreme youth heretofore assigned to these sedimentary formations and the consequent recency of the physiographic development of the Columbia River Gorge. The writers and Mr. John H. Maxson devoted about ten days in July 1927 to a study of the region extending from somewhat east of The Dalles to west of Hood River. Efforts were concentrated on securing fossil material from the formations lying on the Columbia lavas and on determining the relations of these formations to each other. A very brief preliminary statement of results has been published. The investigation was made under the general direction of Dr. John C. Merriam, President of the Carnegie Institution of Washington, as part of a broad program of Tertiary history' studies in the Northwest

Visual suppression of the vestibulo-ocular reflex during space flight

Visual suppression of the vestibulo-ocular reflex was studied in 16 subjects on 4 Space Shuttle missions. Eye movements were recorded by electro-oculography while subjects fixated a head mounted target during active sinusoidal head oscillation at 0.3 Hz. Adequacy of suppression was evaluated by the number of nystagmus beats, the mean amplitude of each beat, and the cumulative amplitude of nystagmus during two head oscillation cycles. Vestibulo-ocular reflex suppression was unaffected by space flight. Subjects with space motion sickness during flight had significantly more nystagmus beats than unaffected individuals. These susceptible subjects also tended to have more nystagmus beats before flight

Eye and head motion during head turns in spaceflight

Eye-head motion was studied pre-, in- and postflight during single voluntary head turns. A transient increase in vestibulo-ocular reflex (VOR) gain occurred early in the flight, but later trended toward normal. This increased gain was produced by a relative increase in eye counterrotation velocity. Asymmetries in gain with right and left turns also occurred, caused by asymmetries in eye counterrotation velocities. These findings were remarkably similar to those from Soviet primate studies using gaze fixation targets, except the human study trended more rapidly toward normal. These findings differ substantially from those measuring VOR gain by head oscillation, in which no significant changes were found inflight. No visual disturbances were noted in either test condition or in normal activities. These head turn studies are the only ones to date documenting any functional change in VOR in weightlessness

Age of the "Satsop" and the Dalles Formations of Oregon and Washington

Geologists have differed regarding the ages of the "Satsop" and the Dalles formations of the Columbia River Gorge region. Because of their bearing on the history of the Gorge and for other reasons their ages are important. During a brief investigation of these beds under the auspices of the Carnegie Institution of Washington, the writers secured fragmentary mammalian fossil remains from the Dalles formation representing not a Quaternary, but approximately an upper Miocene or lower Pliocene stage. This age determination is corroborated by the lithologic resemblance of the Dalles beds to the middle Neocene Ellensburg formation of central Washington, by the apparently similar relations of these two formations to the Columbia lavas, and by the induration of the Dalles beds, which is equal to that of lower or middle Neocene deposits of the west, but much greater than that of Quaternary formations