High repetition rate sealed CO2 TEA lasers using heterogeneous catalysts

The significant operational advantages offered by CO2 lasers, operating in the 10.6 micron region of the spectrum, over current solid state lasers, emitting in the near IR region, have prompted increased interest in the development of compact, reliable, rugged CO2 laser sources. Perhaps the most critical aspect associated with achieving a laser compatible with military use is the development of lasers which require no gas replenishment. Sealed, single shot, CO2 TEA lasers have been available for a number of years. Stark et al were first to demonstrate reliable sealed operation in single shot CO2 TEA lasers in 1975 using gas catalysis. GEC Avionics reported the compact, environmentally qualified, MKIII CO2 TEA laser with a pulse life of greater than 10 to the 6th power pulses in 1980. A sealed laser lifetime of greater than 10 to the 6th power pulses is acceptable for single shot cases, such as direct detection rangefinders for tank laser sights. However, in many other applications, such as tracking of fast moving targets, it is essential that a repetition rate of typically 30Hz to 100Hz is employed. In such cases, a pulse lifetime of 10 to the 6th power pulses is no longer sufficient and a minimum pulse lifetime 10 to the 7th power pulses is essential to ensure a useful service life. In 1983 Stark el al described a sealed, 100Hz CO2 TEA laser, with a life of greater than 2.6 x 10 to the 6th power, which employed heterogeneous catalysis. Following this pioneering work, GEC Avionics has been engaged in the development of sealed high repetition rate lasers with a pulse lifetime of 20 million pulses

Turbofan blade stresses induced by the flow distortion of a VTOL inlet at high angles of attack

A 51-cm-diameter turbofan with a tilt-nacelle VTOL inlet was tested in the Lewis Research Center's 9- by 15-Ft Low Speed Wind Tunnel at velocities up to 72 m/s and angles of attack up to 120 deg. Fan-blade vibratory stress levels were investigated over a full aircraft operating range. These stresses were due to inlet air flow distortion resulting from (1) internal flow separation in the inlet, and (2) ingestion of the exterior nacelle wake. Stress levels are presented, along with an estimated safe operating envelope, based on infinite blade fatigue life

Growing-degree units for corn in the north central region

Growing-degree units were calculated for the North Central Region by using the so-called National Weather Service Method. This adjusts for maximum temperatures above 86°F and for minimum temperatures below 50°F. Growing-degree units were calculated for five different periods: 14 days before the average planting date to the average fall safe-from-frost date, 7 days before the average planting date to the average fall safe-from-frost date, the average planting date to the average fall safe-from-frost date, 7 days after the average planting date to the average fall safe-from-frost date, and 14 days after the average planting date to the average fall safe-from-frost date. Maps are shown giving the average growing-degree units for each of these periods. Also included are data for computing the number of growing-degree units that will be received with 10 different probability levels

Estimation of soil moisture under corn

This study was undertaken as an attempt to develop a simplified approach to a complex problem- the prediction of soil moisture under corn which, at times, may have a limited moisture supply. Soil moisture under corn was estimated for June, early August and early November by using April, June and August soil-moisture survey data as the starting points. All computations were made on the basis of the amount of plant-available water present. To obtain this value, both the field capacity and the wilting point of a soil need to be known. Precipitation amounts were added to the data for soil moisture supply after deducting a value for runoff. An antecedent precipitation index, which \u27Varied with the season, was used to compute runoff. For the April-June period, evaporation was estimated as 0.1 inch per day for as long as any available water was present in the top 6 inches. After early June, evapotranspiration was estimated by using open-pan evaporation data as the measure of the potential for evaporation. This was multiplied by a factor to account for crop development and, when necessary, by a factor that considered any moisture stress present. The product of these values gave the actual evapotranspiration for each day. The water used in evapotranspiration was removed from the shallow depths early in the season, with a gradual increase in the depth of extraction as the season progressed. By Aug. 1, water use was assumed to take place to a depth of 5-feet. Water use was apportioned among the different depths active in water absorption, with the largest percentage coming from the shallow depths

A spectrum of ozone from 760 to 5800 cm-1

An atlas of O3 lines between 760 and 5800/cm obtained from a low pressure, long-path-length sample of O3 at 296K is presented. Many of the line centers are marked and their positions tabulated

Evaporation climatology of Iowa

Class A evaporation-pan observations and évapotranspiration data generated from a soil-moisture program for com have been summarized. Evaporation-pan data provide an estimate of the atmospheric potential for evaporation. These data show that the peak rate occurs in early July, averaging from near 0.26 inch per day in east-central Iowa to 0.29 inch per day in southwestern Iowa. A gradient in the evaporation rate is consistently present across the state throughout the growing season, with higher rates in western Iowa.https://lib.dr.iastate.edu/specialreports/1085/thumbnail.jp

Almanac Weather - How Accurate?

You can check up on the weather forecasting skill of your almanac or, for that matter, your own skill and that of any other long-range forecaster

Electrochemical characterization of systems for secondary battery application Quarterly report, Nov. 1966 - Jan. 1967

Multisweep cyclic voltammograms of electrochemical systems for secondary batterie

Situation Report on Cloud Seeding

The answer to what can be done by cloud seeding is at best still incomplete and inconclusive. More study is needed on the fundamentals of how rain falls and how cloud seeding might modify this. But here\u27s a report on this controversial subject in the light of the information now known