2,552 research outputs found
Lunar material transport vehicle
The proposed vehicle, the Lunar Material Transport Vehicle (LMTV), has a mission objective of efficient lunar soil material transport. The LMTV was designed to meet a required set of performance specifications while operating under a given set of constraints. The LMTV is essentially an articulated steering, double-ended dump truck. The vehicle moves on four wheels and has two identical chassis halves. Each half consists of a chassis frame, a material bucket, two wheels with integral curvilinear synchronous motors, a fuel cell and battery arrangement, an electromechanically actuated dumping mechanism, and a powerful microprocessor. The vehicle, as designed, is capable of transporting up to 200 cu ft of material over a one mile round trip per hour. The LMTV is capable of being operated from a variety of sources. The vehicle has been designed as simply as possible with attention also given to secondary usage of components
A Teachers guide: The basic characteristics of wetlands and why they are important to the environment
The purpose of this thesis is to develop an educational guide about wetlands that can be used by 3rd- 12th grade teachers. This guide will enable students to learn about wetlands and why they are important to our environment. I will provide examples and a series of activities that teachers can use in the classroom to help their students better understand the benefits and function of wetlands
Relative effects on global warming of halogenated methanes and ethanes of social and industrial interest
The relative potential global warming effects for several halocarbons (chlorofluorocarbons (CFC's)-11, 12, 113, 114, and 115; hydrochlorofluorocarbons (HCFC's) 22, 123, 124, 141b, and 142b; and hydrofluorocarbons (HFC's) 125, 134a, 143a, and 152a; carbon tetrachloride; and methyl chloroform) were calculated by two atmospheric modeling groups. These calculations were based on atmospheric chemistry and radiative convective models to determine the chemical profiles and the radiative processes. The resulting relative greenhouse warming when normalized to the effect of CFC-11 agree reasonably well as long as we account for differences between modeled lifetimes. Differences among results are discussed. Sensitivity of relative warming values is determined with respect to trace gas levels assumed. Transient relative global warming effects are analyzed
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Hydrology of an Evaporite Aquitard Permian Evaporite
Permian evaporite strata of the Palo Duro Basin, Texas Panhandle, are considered to have low permeabilities but are capable of some leakage. Cross-sectional and areal modeling of regional groundwater flow in the Palo Duro Basin indicates leakage from the Upper aquifer through the Evaporite aquitard that contributes approximately 30 percent of the water in the underlying Deep-Basin Brine aquifer. The regional estimate of permeability of the aquitard (˜ 10^-4 md) is in general agreement with laboratory testing of salt permeability. Oxygen and hydrogen isotopic composition and the Cl/Br ratio of the deep-basin brines also suggest leakage through the aquitard. Isotopically nonequilibrated meteoric waters are found to depths of 8,000 ft.
Leakage through the aquitard may occur as either matrix or fracture flow. According to petrographic and geochemical studies of the evaporite strata, halite dissolution and minor recrystallization occurred predominantly during Permian time. Post-Permian waters may have altered the top of the Evaporite aquitard. Fracturing is prevalent in the rock strata in the basin; the greatest density of fracturing occurs in areas with tectonic deformation. The potential for leakage may be greatest in these areas.Bureau of Economic Geolog
Patterns of Psychotherapy Attendance in Emerging and Mature Adults
Approximately 760,000 emerging adults use outpatient psychotherapy in the U.S. each year (Olfson et al.,2002). Emerging adults are 1.6-7.9 times more likely to drop out of mental health treatment than fully mature adults (Edlund et al., 2002; Olfson et al., 2002). This Study compared temporal patterns of attendance and non attendance between emerging and mature adult
Ursinus College Bulletin Vol. 6, No. 6
A digitized copy of the March 1890 Ursinus College Bulletin.https://digitalcommons.ursinus.edu/ucbulletin/1054/thumbnail.jp
A disk census for the nearest group of young stars: Mid-infrared observations of the TW Hydrae Association
A group of young, active stars in the vicinity of TW Hydrae has recently been
identified as a possible physical association with a common origin. Given its
proximity (50 pc), age (10 Myr) and abundance of binary systems,
the TW Hya Association is ideally suited to studies of diversity and evolution
of circumstellar disks. Here we present mid-infrared observations of 15
candidate members of the group, 11 of which have no previous flux measurements
at wavelengths longer than 2m. We report the discovery of a possible
10m excess in CD -337795, which may be due to a circumstellar
disk or a faint, as yet undetected binary companion. Of the other stars, only
TW Hya, HD 98800, Hen 3-600A, and HR 4796A -- all of which were detected by
IRAS -- show excess thermal emission. Our 10m flux measurements for the
remaining members of the Association are consistent with photospheric emission,
allowing us to rule out dusty inner disks. In light of these findings, we
discuss the origin and age of the TW Hya Association as well as implications
for disk evolution timescales.Comment: 10 pages and 1 PostScript figure, accepted for publication in The
Astrophysical Journal Letter
Pulsewidth dependence of ozone interference in the laser fluorescence measurement of OH in the atmosphere
By varying the pulsewidth of the output from two dye lasers, we have verified experimentally that the steady‐state interference level of OH due to laser‐induced dissociation of ozone decreases linearly with decreasing pulsewidth of the exciting radiation. At low pressures, further reduction in the interference level due to the transient nature of OH formation processes was also observed. These results should greatly facilitate measurements of OH concentrations in the atmosphere.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70170/2/JCPSA6-66-5-2118-1.pd
Re\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e7\u3c/sub\u3e-catalyzed reaction of hemiacetals and aldehydes with O-, S-, and C-nucleophiles
Re(VII) oxides catalyze the acetalization, monoperoxyacetalization, monothioacetalization and allylation of hemiacetals. The reactions, which take place under mild conditions and at low catalyst loadings, can be conducted using hemiacetals, the corresponding O-silyl ethers, and, in some cases, the acetal dimers. Aldehydes react under similar conditions to furnish good yields of dithioacetals. Reactions of hemiacetals with nitrogen nucleophiles are unsuccessful. 1,2-Dioxolan-3-ols (peroxyhemiacetals) undergo Re(VII)-promoted etherification but not allylation. Hydroperoxyacetals (1-alkoxyhydroperoxides) undergo selective exchange of the alkoxide group in the presence of either Re2O7 or a Brønsted acid
Re\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e7\u3c/sub\u3e-catalyzed reaction of hemiacetals and aldehydes with O-, S-, and C-nucleophiles
Re(VII) oxides catalyze the acetalization, monoperoxyacetalization, monothioacetalization and allylation of hemiacetals. The reactions, which take place under mild conditions and at low catalyst loadings, can be conducted using hemiacetals, the corresponding O-silyl ethers, and, in some cases, the acetal dimers. Aldehydes react under similar conditions to furnish good yields of dithioacetals. Reactions of hemiacetals with nitrogen nucleophiles are unsuccessful. 1,2-Dioxolan-3-ols (peroxyhemiacetals) undergo Re(VII)-promoted etherification but not allylation. Hydroperoxyacetals (1-alkoxyhydroperoxides) undergo selective exchange of the alkoxide group in the presence of either Re2O7 or a Brønsted acid
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