Investigations of negative and positive cesium ion species

A direct test is provided of the hypothesis of negative ion creation at the anode or collector of a diode operating under conditions simulating a cesium thermionic converter. The experimental technique involves using direct ion sampling through the collector electrode with mass analysis using a quadrupole mass analyzer. Similar measurements are undertaken on positive ions extracted through the emitter electrode. Measurements were made on a variety of gases including pure cesium, helium-cesium mixtures and cesium-hydrogen as well as cesium-xenon mixtures. The gas additive was used primarily to aid in understanding the negative ion formation processes. Measurements were conducted using emitter (cathode) temperatures up to about 1000 F. The major negative ion identified through the collector was Cs(-) with minor negative ion peaks tentatively identified as H(-), H2(-), H3(-), He(-) and a mass 66. Positive ions detected were believed to be Cs(+), Cs2(+) and Cs3(+)

Investigation of critical burning of fuel droplets

The steady combustion characteristics of droplets were considered in combustion chamber environments at various pressures, flow conditions, and ambient oxidizer concentrations for a number of hydrocarbon fuels. Using data obtained earlier, predicted gasification rates were within + or - 30% of measurements when the correction for convection was based upon average properties between the liquid surface and the flame around the droplet. Analysis was also completed for the open loop response of monopropellant droplets, based upon earlier strand combustion results. At the limit of large droplets, where the effect of flame curvature is small, the results suggest sufficient response to provide a viable mechanism for combustion instability in the frequency and droplet size range appropriate to practical combustors. Calculations are still in progress for a broader range of droplet sizes, including conditions where active combustion effects are small

Seasonal variation of the 11 year solar cycle effect on the middle atmosphere: Role of the quasi biennial oscillation

Before the introduction of the Quasi Biennial Oscillation (Q.B.O.) in the study of the solar atmosphere relationship by Labitzke (1987) and Labitzke and Van Loon (1988), the only region of the atmosphere where an effect of a change in solar activity was generally admitted was the mesosphere. The response of the mesosphere, in phase with the solar activity, was found to be about one order of magnitude above model expectancy (around 10 to 20 Kelvin). It was observed independently of the season and maximized around 70 km (Chanin et al. 1987). However, from the same study, it was shown that the response of the stratosphere of opposite sign, clearly seen during winter and autumn, was at the threshold of detection in spring and summer. In the stratosphere, it was shown later that the separation of the data taking into account the sign of the Q.B.O. amplifies the negative correlation of the stratospheric temperature with solar activity in winter; it then becomes more significantly negative for the East phase of the Q.B.O. than when the data are all mixed (Labitzke and Chanin 1988). The studies of the seasonal response of the atmosphere to solar effect is crucial to understand the possible mechanism responsible of such a solar activity Q.B.O. relationship, knowing that the global dynamic circulation is quite different according to the seasons. The question is examined as to whether such separation of the data according to the phase of the Q.B.O. has any impact on the solar response of the middle atmosphere for seasons other than winter

Investigation of critical burning of fuel droplets

Steady and unsteady combustion of liquid fuel droplets under rocket engine conditions was analyzed. Emphasis was placed on combustion at elevated pressures and temperatures. The results and their technical application to the design of liquid fueled rocket engines and the determination of combustion instability characteristics of these engines were summarized

Letter to Pearl Von Allmen regarding President plaque, September 11, 1972

A letter from Leah Chanin to Pearl Von Allmen thanking SEAALL for a plaque commemorating Chanin\u27s work as SEAALL President

Oscillatory combustion of liquid monopropellant droplets

A theoretical investigation was conducted on the open-loop combustion response of monopropellant droplets and sprays to imposed pressure oscillations. The theoretical model was solved as a perturbation analysis through first order, yielding linear response results. Unsteady gas phase effects were considered in some cases, but the bulk of the calculations assumed a quasi-steady gas phase. Calculations were conducted using properties corresponding to hydrazine decomposition. Zero-order results agreed with earlier measurements of hydrazine droplet burning in combustion gases. The droplet response was greatest (exceeding unity in some cases) for large droplets with liquid phase temperature gradients; at frequencies near the characteristic frequency of the liquid phase thermal wave. The response of a spray is less than that of its largest droplet, however, a relatively small percentage of large droplets provides a substantial response (exceeding unity in some cases)

Monitoring otter populations by DNA typing of spraints

To monitor mammals by direct observation is often very difficult. Therefore a new technique based on DNA typing of droppings has been developed. DNA typing of otter spraints can potentially provide estimates of population size, home ranges, dispersal, genetic diversity and which species are present. This article gives a set of guidelines based on two feasibility studies on how to use the spraint DNA typing method. There are three main points. First, a sample of the study population must be typed to check that levels of genetic polymorphism are high enough for individual identification. Second, spraints must be collected and stored correctly because DNA extracted from spraints is typically of poor quality and quantity. Spraint collection should take place within 12 hours after deposition and before 10 a.m., and spraints should be stored at -20°C in a solution to stop DNA breakdown. Third, laboratory technique must be meticulous in carrying out repeat assays of the same sample and in avoiding contamination among samples. The results of the feasibility studies suggest that spraint DNA typing shows promise for monitoring of otter populations. Further progress will depend on achieving higher success rates, lower cost, and developing more highly variable microsatellites and species-specific PCR assays. DNA typing of endangered and poorly known otter species could provide important information on their distribution and status. We therefore recommend that skin, tissue or DNA samples from all endangered otter species be archived for future genetic analysi

Letter to Scholarship Committee members regarding scholarship applications, March 31, 1976

A letter from Leah Chanin to Scholarship Committee members enclosing application materials for candidates for the Lucile Elliott Scholarship

Letter to William Younger regarding SEAALL letterhead, May 6, 1974

A letter from Leah Chanin to William Younger regarding the SEAALL letterhead

Factors Affecting Knowledge Conversion of Thai Bank Branches

This study focuses on factors affecting knowledge conversion of bank branches in Thailand. The four factors were information technology support, teamworking, social network and internal communication. The findings indicated that social network and information technology support had high influence on knowledge conversion respectively. The suggestions and directions for future research in the areas of knowledge management were also discussed