Melting of troilite at high pressure in a diamond cell by laser heating

A system for measuring melting temperatures at high pressures is described. The sample is heated with radiation from a YAG laser. The beam is reflected downward through a microscope objective, through the upper diamond anvil, and focused onto the sample. Hense, intense heating is produced only at the sample and not within the diamond anvils. A vidicon system is used to observe the sample during heating. Incandescent light from the heated sample passes back through the objective lens into a grating spectrometer. The spectrum of the incandescent light is received by the photodiode array and stored in the multichannel analyzer. These data can then be transferred to floppy disk for analysis. A curve fitting program is used to compare the spectra with standard blackbody curves and to determine the temperature. Pressure is measured by the ruby fluorescence method. The system was used to study the melting behavior of natural troilite (FeS)

A Study of the Ecological Distribution of Income, Education and Occupation in Omaha, Nebraska

A social ecological study involves the spatial, selective and distributive functions and relations of human beings in a given geographical and cultural area. In the present study, Omaha is viewed as an ecological area for purposes of the following analysis. Briefly stated, the purpose of this study is to present the ecological distribution of income, education, and occupation in the several census tracts in Omaha, Nebraska. Following the pattern of ecological studies in general, it is assumed that such characteristics will be distributed in a pattern. Ecological distribution, of these indices, refers to the differential distributionof Income, education, and occupation in Omaha. An arbitrary scaling technique, representing numbers from 1 to ”5 , was employed in order to measure and classify the different levels in the various tracts and to draw conclusions therefrom

Opportunities for building design and construction resulting from local resources

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 2007.Includes bibliographical references (p. 48-51).Current and future generations of architects must learn to operate effectively in an era of unprecedented resource constraints if they want to achieve their design intentions. This thesis addresses the architect's role in resource consumption. Specifically, it explores the potential for design and construction constrained to local resources. This research encompasses the following questions:What are the material resources local to MIT? What are the architectural and logistical limitations of using those resources in buildings? How might this research shape a building at MIT? By auditing local resources and industries, this thesis highlights unique opportunities for an architect to mobilize sustainable materials for MIT's growth. The subsequent design exercise transforms this knowledge into building strategies responsive to material and energy constraints. This new building serves to increase the density of MIT's east campus, developing underutilized lots on the edge of a future quad and rehabilitating a condemned structure. A framework of fixed and fluid components allows for sustainable adaptation, creating a flexible environment sought by emerging interdisciplinary groups.by Thomas A. Weathers.M.Arch

Effects of horizontal vibration on hopper flows of granular materials

The current experiments investigate the discharge of glass spheres in a planar wedge-shaped hopper (45 degree sidewalls) that is vibrated hoizontally. When the hopper is discharged without vibration, the discharge occurs as a funnel flow, with the material exiting the central region of the hopper and stagnant material along the sides. With horizontal vibration, the discharge rate increases with the velocity of vibration as compared with the discharge rate without vibration. For a certain range of acceleration parameters (20-30 Hz and accelerations greater than about 1 g), the discharge of the material occurs in an inverted-funnel pattern, with the material along the sides exiting first, followed by the material in the core; the free surface shows a peak at the center of the hopper with the free surface particles avalanching from the center toward the sides. During the deceleration phase of a vibration cycle, particles all along the trailing or low-pressure wall separate from the surface and fall under gravity for a short period before reconnecting the hopper. For lower frequencies (5 and 10 Hz), the free surface remains horizontal and the material appears to discharge uniformly from the hopper

Dashboard Lights: Monitoring Implementation of District Instructional Reform Strategies

In this report, the authors describe the system implemented in Duval County Public Schools (Florida) to monitor the district’s instructional reform efforts and the influences of the system on teachers and school and district leaders. The system, called the Standards Implementation Snapshot System, was implemented by John Fryer, Superintendent of Duval Public Schools, in 2002. The snapshot system seeks to take a snapshot at a point in time of the depth of implementation of the district’s standards-based reform initiatives. This report is the story of the development and influence of the snapshot system

Effects of Horizontal Vibration on Hopper Flows of Granular Material

This study experimentally examines the flow of glass spheres in a wedge-shaped hopper that is vibrated hoizontally. When the hopper is discharged without vibration, discharge occurs as a funnel flow, with the material exiting the central region of the hopper and stagnant material along the sides. With vibration, the discharge of the material occurs in reverse, with the material along the sides exiting first, followed by the material in the central region. These patterns are observed with flow visualization and high-speed photography. The study also includes measurements of the discharge rate, which increases with the amplitude of the velocity of vibration

Calculation of clearances in twin screw compressors

Clearances between rotating and stationary parts in a screw compressor are set to ensure the efficient operation and allow for thermal deformation without unwanted contacts. The change in clearances is caused by both pressure and temperature changes within the machine. If clearances are too large, the increased leakage flows will reduce efficiency. However, if the nominal clearances are too small, contacts between the rotating and stationary parts can occur as a consequence of rotor and casing deformations. In order to determine the operational clearances, a numerical analysis of deformation of screw compressor rotors and casing has to be performed. This paper discusses how the temperature of rotor and casing surfaces calculated from the one-dimensional chamber model in the SCORG could be used as a boundary conditions for a steady state thermal and structural analysis of a screw compressor solid parts. Deformations of rotors and casing under temperature load were calculated using a commercial Finite Element Analysis code ANSYS. Operational clearance are estimated from these deformations and some recommendations for further work are proposed

Collaborative Understanding of Cyanobacteria in Lake Ecosystems

We describe a collaboration between mathematicians and ecologists studying the cyanobacterium Gloeotrichia echinulata and its possible role in eutrophication of New England lakes. The mathematics includes compartmental modeling, differential equations, difference equations, and testing models against high-frequency data. The ecology includes observation, field sampling, and parameter estimation based on observed data and the related literature. Mathematically and ecologically, a collaboration like this progresses in ways it never would have if either group worked alone