5,689 research outputs found
Water for agriculture. 6. Control of algae in water supplies
ALGAE are primitive forms of plant life that are common and normal in surface waters. They are fonnd in every water supply exposed to sunlight.
Their presence is not normally detectable until there are enough of them to make their presence obvious
Development and evaluation of lessons for class and group situations in grade I. Volume I.
Thesis (Ed.M.)--Boston University
For volume II, please see: http://hdl.handle.net/2144/1415
Environmental Dependence of the Fundamental Plane of Galaxy Clusters
Galaxy clusters approximate a planar (FP) distribution in a three-dimensional
parameter space which can be characterized by optical luminosity, half-light
radius, and X-ray luminosity. Using a high-quality catalog of cluster
redshifts, we find the nearest neighbor cluster for those common to an FP study
and the cluster catalog. Examining scatter about the FP, we find 99.2%
confidence that it is dependent on nearest neighbor distance. Our study of
X-Ray clusters finds that those with high central gas densities are
systematically closer to neighbor clusters. If we combine results here with
those of Fritsch and Buchert, we find an explanation for some of our previous
conclusions: Clusters in close proximity to other clusters are more likely to
have massive cooling flows because they are more relaxed and have higher
central gas densities.Comment: Accepted for publication in Astrophysical Journal Letters. Moderate
revisions, including more statistical analysis and discussion. Latex, 7 page
Orbital assembly and maintenance study
The requirements, conceptual design, tradeoffs, procedures, and techniques for orbital assembly of the support structure of the microwave power transmission system and the radio astronomy telescope are described. Thermal and stress analyses, packaging, alignment, and subsystems requirements are included along with manned vs. automated and transportation tradeoffs. Technical and operational concepts for the manned and automated maintenance of satellites were investigated and further developed results are presented
Orbital assembly and maintenance study. Executive summary
A sound, practical approach for the assembly and maintenance of very large structures in space is presented. The methods and approaches for assembling two large structures are examined. The maintenance objectives include the investigation of methods to maintain five geosynchronous satellites. The two assembly examples are a 200-meter-diameter radio astronomy telescope and a 1,000-meter-diameter microwave power transmission system. The radio astronomy telescope operates at an 8,000-mile altitude and receives RF signals from space. The microwave power transmission system is part of a solar power satellite that will be used to transmit converted solar energy to microwave ground receivers. Illustrations are included
Patient-specific CFD models for intraventricular flow analysis from 3D ultrasound imaging : comparison of three clinical cases
Background: As the intracardiac flow field is affected by changes in shape and motility of the heart, intraventricular flow features can provide diagnostic indications. Ventricular flow patterns differ depending on the cardiac condition and the exploration of different clinical cases can provide insights into how flow fields alter in different pathologies. Methods: In this study, we applied a patient-specific computational fluid dynamics model of the left ventricle and mitral valve, with prescribed moving boundaries based on transesophageal ultrasound images for three cardiac pathologies, to verify the abnormal flow patterns in impaired hearts. One case (P1) had normal ejection fraction but low stroke volume and cardiac output, P2 showed low stroke volume and reduced ejection fraction, P3 had a dilated ventricle and reduced ejection fraction. Results: The shape of the ventricle and mitral valve, together with the pathology influence the flow field in the left ventricle, leading to distinct flow features. Of particular interest is the pattern of the vortex formation and evolution, influenced by the valvular orifice and the ventricular shape. The base-to-apex pressure difference of maximum 2 mmHg is consistent with reported data. Conclusion: We used a CFD model with prescribed boundary motion to describe the intraventricular flow field in three patients with impaired diastolic function. The calculated intraventricular flow dynamics are consistent with the diagnostic patient records and highlight the differences between the different cases. The integration of clinical images and computational techniques, therefore, allows for a deeper investigation intraventricular hemodynamics in patho-physiology. (C) 2016 Elsevier Ltd. All rights reserved
Supercritical Water Gasification: Practical Design Strategies and Operational Challenges for Lab-Scale, Continuous Flow Reactors
Optimizing an industrial-scale supercritical water gasification process
requires detailed knowledge of chemical reaction pathways, rates, and product
yields. Laboratory-scale reactors are employed to develop this knowledge base.
The rationale behind designs and component selection of continuous flow,
laboratory-scale supercritical water gasification reactors is analyzed. Some
design challenges have standard solutions, such as pressurization and
preheating, but issues with solid precipitation and feedstock pretreatment
still present open questions. Strategies for reactant mixing must be evaluated
on a system-by-system basis, depending on feedstock and experimental goals, as
mixing can affect product yields, char formation, and reaction pathways.
In-situ Raman spectroscopic monitoring of reaction chemistry promises to
further fundamental knowledge of gasification and decrease experimentation
time. High-temperature, high-pressure spectroscopy in supercritical water
conditions is performed, however, long-term operation flow cell operation is
challenging. Comparison of Raman spectra for decomposition of formic acid in
the supercritical region and cold section of the reactor demonstrates the
difficulty in performing quantitative spectroscopy in the hot zone. Future
designs and optimization of SCWG reactors should consider well-established
solutions for pressurization, heating, and process monitoring, and effective
strategies for mixing and solids handling for long-term reactor operation and
data collection
The complications of âhiring a hubbyâ: gender relations and the commoditisation of home maintenance in New Zealand
This paper examines the commoditization of traditionally male domestic tasks through interviews with handymen who own franchises in the company âHire a Hubbyâ in New Zealand and homeowners who have paid for home repair tasks to be done. Discussions of the commoditization of traditionally female tasks in the home have revealed the emotional conflicts of paying others to care as well as the exploitative and degrading conditions that often arise when work takes place behind closed doors. By examining the working conditions and relationships involved when traditionally male tasks are paid for, this paper raises important questions about the valuing of reproductive labour and the production of gendered identities. The paper argues that while working conditions and rates of pay for âhubbiesâ are better than those for people undertaking commoditized forms of traditionally female domestic labour, the negotiation of this work is still complex and implicated in gendered relations and identities. Working on the home was described by interviewees as an expression of care for family and a performance of the ârightâ way to be a âKiwi blokeâ and a father. Paying others to do this labour can imply a failure in a duty of care and in the performance of masculinity
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