Evaluation of an electro-optic remote displacement measuring system

An instrumentation system to provide a noncontact method for measurement of target positions was evaluated. The system employs two electro-optic camera units which give stereo information for use in determining three dimensional target locations. Specially developed, infrared sensitive photodetectors are used in the cameras to sense radiation from light emitting diode targets. Up to 30 of these targets can be monitored with a sampling rate of 312 Hz per target. An important part of the system is a minicomputer which is used to collect the camera data, sort it, make corrections for distortions in the electro-optic system, and perform the necesssary coordinate transformations. If target motions are restricted to locations in a plane which is perpendicular to a camera's optical axis, the system can be used with just one camera. Calibrations performed in this mode characterize accuracies in single camera operation. This information is also useful in determination of single camera contributions to total system errors. For this reason the system was tested in both the single camera and two camera (stereo) modes of operation

An investigation of thin film oxygen partial pressure sensors

Product development and testing of thin film oxygen partial pressure sensor

A study of charge storage in silicon oxide resulting from non-penetrating electron irradiation

Charge storage in silicon dioxide resulting from electron irradiatio

Charge storage effects in Mylar resulting from electron irradiation, June 1965 - June 1966

Charge storage effects in Mylar from electron irradiatio

Study of the use of Metal-Oxide-Silicon (MOS) devices for particulate detection and monitoring in the earth's atmosphere

A metal-oxide-silicon (MOS) capacitor-type particulate sensor was evaluated for use in atmospheric measurements. An accelerator system was designed and tested for the purpose of providing the necessary energy to trigger the MOS-type sensor. The accelerator system and the MOS sensor were characterized as a function of particle size and velocity. Diamond particles were used as particulate sources in laboratory tests. Preliminary tests were performed in which the detector was mounted on an aircraft and flown in the vicinity of coal-fired electric generating plants

Particulate and aerosol detector

A device is described for counting aerosols and sorting them according to either size, mass or energy. The component parts are an accelerator, a capacitor sensor and a readout. The accelerator is a means for accelerating the aerosols toward the face of the capacitor sensor with such force that they partially penetrate the capacitor sensor, momentarily discharging it. The readout device is a means for counting the number of discharges of the capacitor sensor and measuring the amplitudes of these different discharges. The aerosols are accelerated by the accelerator in the direction of the metal layer with such force that they penetrate the metal and damage the oxide layers, thereby allowing the electrical charge on the capacitor to discharge through the damaged region. Each incident aerosol initiates a discharge path through the capacitor in such a fashion as to vaporize the conducting path. Once the discharge action is complete, the low resistance path no longer exists between the two capacitor plates and the capacitor is again able to accept a charge. The active area of the capacitor is reduced in size by the damaged area each time a discharge occurs

Weather and water in the Sudano-Sahelian Zone

Evaporation horn bare soll surfaces and from vegetation plays a dominant role in the watcr balance of the Sudano-Sahelian zone. Starting from the formula first derived by Penman, equations are derived for (i) evaporation hom bare soil: (ii) potential transpiration hom well-watered crop stands; and (iii) actual evaporation from a reglon. ll~cae equations were used to estimate rates of evaporation in southern Nkr with emphasis on the contrast bchvccn a vcrv dw y~ar(1 984) and n set vear 11988). ~hacnn ual evaporation f;om-d.re Dbi~ ia estimated io be'aboit 230 mm. Potential evaporation from uopa In the wst season is close to 6 mm per day, consistent with meaarrcmmts by Dancctte, but is underestimated in the dry sewn by the original Penman equation and by the Priestlcy-Taylor equation Actual reglonal evaporation estimated belwr.cn 1984 and 1989 ranged between 300 and 500 mm. Corresponding esHrnates of runoff arc consistent wlth published measurements raneine horn about 30 to 230 mm for areas with little vegetation and horn rcro to about 110 mm for areas with 50% vegetatio

Contrasting stomatal sensitivity to temperature and soil drought in mature alpine conifers

Conifers growing at high elevations need to optimize their stomatal conductance (g(s)) for maximizing photosynthetic yield while minimizing water loss under less favourable thermal conditions. Yet the ability of high-elevation conifers to adjust their g(s) sensitivity to environmental drivers remains largely unexplored. We used 4 years of sap flow measurements to elucidate intraspecific and interspecific variability of g(s) in Larix decidua Mill. and Picea abies (L.) Karst along an elevational gradient and contrasting soil moisture conditions. Site- and species-specific g(s) response to main environmental drivers were examined, including vapour pressure deficit, air temperature, solar irradiance, and soil water potential. Our results indicate that maximum g(s) of L. decidua is >2 times higher, shows a more plastic response to temperature, and down-regulates g(s) stronger during atmospheric drought compared to P. abies. These differences allow L. decidua to exert more efficient water use, adjust to site-specific thermal conditions, and reduce water loss during drought episodes. The stronger plasticity of g(s) sensitivity to temperature and higher conductance of L. decidua compared to P. abies provide new insights into species-specific water use strategies, which affect species' performance and should be considered when predicting terrestrial water dynamics under future climatic change