A Low‐Cost Spatial Equilibrium Solution Procedure

1972 ◽  
Vol 54 (2) ◽  
pp. 373-374 ◽  
Author(s):  
Foo‐Shiung Ho ◽  
Richard A. King
Keyword(s):  
Equilibrium Solution ◽  
Low Cost ◽  
Solution Procedure ◽  
Spatial Equilibrium

The outcome of a general spatial epidemic on the line

1983 ◽  
Vol 20 (04) ◽  
pp. 715-727 ◽  
Author(s):  
M. J. Faddy
Keyword(s):  
Equilibrium Solution ◽  
Numerical Results ◽  
Quasi Equilibrium ◽  
Deterministic Case ◽  
Spatial Equilibrium ◽  
Threshold Behaviour ◽  
Stochastic Epidemic ◽  
Stochastic Case ◽  
Spatial Epidemic

The general (non-spatial) stochastic epidemic is extended to allow infective individuals to move forward through a system of spatially connected locations · ··, L 1, L 2, · ·· (on the line) each containing susceptible individuals and the outcome of the epidemic in each of these locations is then considered. In the deterministic case, a (spatial) equilibrium solution and threshold behaviour are discussed. In the stochastic case, a (spatial) quasi-equilibrium behaviour (conditional on sufficient numbers of infectives present) is discussed; numerical results suggest some correspondence between this stochastic quasi-equilibrium and the deterministic equilibrium.

The outcome of a general spatial epidemic on the line

1983 ◽  
Vol 20 (4) ◽  
pp. 715-727 ◽  
Author(s):  
M. J. Faddy
Keyword(s):  
Equilibrium Solution ◽  
Numerical Results ◽  
Quasi Equilibrium ◽  
Deterministic Case ◽  
Spatial Equilibrium ◽  
Threshold Behaviour ◽  
Stochastic Epidemic ◽  
Stochastic Case ◽  
Spatial Epidemic

The general (non-spatial) stochastic epidemic is extended to allow infective individuals to move forward through a system of spatially connected locations · ··, L1, L2, · ·· (on the line) each containing susceptible individuals and the outcome of the epidemic in each of these locations is then considered. In the deterministic case, a (spatial) equilibrium solution and threshold behaviour are discussed. In the stochastic case, a (spatial) quasi-equilibrium behaviour (conditional on sufficient numbers of infectives present) is discussed; numerical results suggest some correspondence between this stochastic quasi-equilibrium and the deterministic equilibrium.

Computer Prediction of Local Destratification Near Low-Level Release Structures of Reservoirs

1983 ◽  
Vol 105 (1) ◽  
pp. 65-70 ◽  
Author(s):  
A. A. Busnaina ◽  
D. G. Lilley
Keyword(s):  
Low Cost ◽  
Three Dimensional ◽  
Axial Flow ◽  
Solution Procedure ◽  
Design Parameters ◽  
Fundamental Study ◽  
Computer Prediction ◽  
Practical Applications ◽  
Low Level ◽  
Dimensional Simulation

The Garton Pump consists of a low-energy axial flow propeller placed just below the surface so as to provide a downward directed jet of fluid and thereby locally mix reservoirs near the release structure of the dam. In this way high-quality epilimnion water is transported downwards, so obtaining local destratification and improved release water quality in the vicinity of low-level release structures. The flowfield is fully three-dimensional and a simplified numerical simulation and solution procedure has been formulated in Cartesian coordinates to include species diffusion and buoyancy forces. Comparison of predictions with experimenal data confirms that the main dynamic effects are modeled adequately and better than a previous two-dimensional simulation. This fundamental study with practical applications represents a low cost basic tool to show the influence of design parameters on the practical flowfield.

The static equilibrium of drag anchors in sand

1996 ◽  
Vol 33 (4) ◽  
pp. 574-583 ◽  
Author(s):  
S R Neubecker ◽  
M F Randolph
Keyword(s):  
Equilibrium Solution ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Limit Equilibrium Method ◽  
Solution Procedure ◽  
Static Equilibrium ◽  
Static Limit ◽  
Centrifuge Model ◽  
Calcareous Sands ◽  
Good Agreement

This paper examines the static equilibrium of drag anchors during embedment in sand. A limit equilibrium method is developed to allow the anchor holding capacity to be predicted given a specific anchor geometry and position relative to the free surface of the sand. The method is based on the earlier approach of Le Lievre and Tabatabaee, but is extended to include a three-dimensional soil wedge, which is consistent with experimental observation. The solution procedure is also extended to be more applicable for anchors at a preultimate stage by incorporating a force behind the anchor fluke. To calibrate the method, a series of centrifuge model anchor tests has been performed in silica and calcareous sands. The static capacity of the anchor during embedment is compared with the static limit equilibrium solution and good agreement is demonstrated. Key words: drag anchor, statics, sand, limit equilibrium, ultimate holding capacity.

Decomposition of the metastable beta titanium alloy Ti-15-3

1983 ◽  
Vol 41 ◽  
pp. 264-265
Author(s):  
Y. L. Chen ◽  
S. Fujlshiro
Keyword(s):  
Low Cost ◽  
High Strength ◽  
Alpha Phase ◽  
Thick Sheet ◽  
Omega Phase ◽  
Beta Titanium Alloy ◽  
Beta Titanium ◽  
Beta Matrix ◽  
Metastable Beta ◽  
Very High

Metastable beta titanium alloys have been known to have numerous advantages such as cold formability, high strength, good fracture resistance, deep hardenability, and cost effectiveness. Very high strength is obtainable by precipitation of the hexagonal alpha phase in a bcc beta matrix in these alloys. Precipitation hardening in the metastable beta alloys may also result from the formation of transition phases such as omega phase. Ti-15-3 (Ti-15V- 3Cr-3Al-3Sn) has been developed recently by TIMET and USAF for low cost sheet metal applications. The purpose of the present study was to examine the aging characteristics in this alloy.The composition of the as-received material is: 14.7 V, 3.14 Cr, 3.05 Al, 2.26 Sn, and 0.145 Fe. The beta transus temperature as determined by optical metallographic method was about 770°C. Specimen coupons were prepared from a mill-annealed 1.2 mm thick sheet, and solution treated at 827°C for 2 hr in argon, then water quenched. Aging was also done in argon at temperatures ranging from 316 to 616°C for various times.

Chromic Acid Etching of Polyethylene

1973 ◽  
Vol 31 ◽  
pp. 72-73
Author(s):  
J. D. Muzzy ◽  
R. D. Hester ◽  
J. L. Hubbard
Keyword(s):  
Chromic Acid ◽  
Low Cost ◽  
Acid Etching ◽  
Crystalline Morphology ◽  
Bulk Specimen ◽  
Morphological Studies ◽  
Perfect Form ◽  
Molecular Length ◽  
Lamellar Texture ◽  
Cost Studies

Polyethylene is one of the most important plastics produced today because of its good physical properties, ease of fabrication and low cost. Studies to improve the properties of polyethylene are leading to an understanding of its crystalline morphology. Polyethylene crystallized by evaporation from dilute solutions consists of thin crystals called lamellae. The polyethylene molecules are parallel to the thickness of the lamellae and are folded since the thickness of the lamellae is much less than the molecular length. This lamellar texture persists in less perfect form in polyethylene crystallized from the melt.Morphological studies of melt crystallized polyethylene have been limited due to the difficulty of isolating the microstructure from the bulk specimen without destroying or deforming it.

Glass Knife Geometry as Seen by the SEM

1971 ◽  
Vol 29 ◽  
pp. 454-455
Author(s):  
J. Temple Black
Keyword(s):  
Low Cost ◽  
Amorphous Material ◽  
Stress Concentrations ◽  
Basic Tool ◽  
Tool Materials ◽  
Optical Inspection ◽  
Surface Flaws ◽  
Slip Planes ◽  
Glass Knife ◽  
Diamond Knife

In ultramicrotomy, the two basic tool materials are glass and diamond. Glass because of its low cost and ease of manufacture of the knife itself is still widely used despite the superiority of diamond knives in many applications. Both kinds of knives produce plastic deformation in the microtomed section due to the nature of the cutting process and microscopic chips in the edge of the knife. Because glass has no well defined slip planes in its structure (it's an amorphous material), it is very strong and essentially never fails in compression. However, surface flaws produce stress concentrations which reduce the strength of glass to 10,000 to 20,000 psi from its theoretical or flaw free values of 1 to 2 million psi. While the microchips in the edge of the glass or diamond knife are generally too small to be observed in the SEM, the second common type of defect can be identified. This is the striations (also termed the check marks or feathers) which are always present over the entire edge of a glass knife regardless of whether or not they are visable under optical inspection. These steps in the cutting edge can be observed in the SEM by proper preparation of carefully broken knives and orientation of the knife, with respect to the scanning beam.

Spectraplot: A PC-based spectrum translation and display program

1988 ◽  
Vol 46 ◽  
pp. 918-919
Author(s):  
H. O. Colijn
Keyword(s):  
Low Cost ◽  
Transfer Program ◽  
File Transfer ◽  
Transfer Data ◽  
Error Checking ◽  
Data Files ◽  
The University

Many labs today wish to transfer data between their EDS systems and their existing PCs and minicomputers. Our lab has implemented SpectraPlot, a low- cost PC-based system to allow offline examination and plotting of spectra. We adopted this system in order to make more efficient use of our microscopes and EDS consoles, to provide hardcopy output for an older EDS system, and to allow students to access their data after leaving the university.As shown in Fig. 1, we have three EDS systems (one of which is located in another building) which can store data on 8 inch RT-11 floppy disks. We transfer data from these systems to a DEC MINC computer using “SneakerNet”, which consists of putting on a pair of sneakers and running down the hall. We then use the Hermit file transfer program to download the data files with error checking from the MINC to the PC.

Transmission Electron Microscopy of oriented Co84Cr14Ta2 thin films for longitudinal magnetic recording

1991 ◽  
Vol 49 ◽  
pp. 756-757
Author(s):  
T. P. Nolan
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Cost ◽  
Low Noise ◽  
Information Storage ◽  
High Coercivity ◽  
Magnetic Alloy ◽  
Magnetic Media ◽  
Transmission Electron

Thin film magnetic media are being used as low cost, high density forms of information storage. The development of this technology requires the study, at the sub-micron level, of morphological, crystallographic, and magnetic properties, throughout the depth of the deposited films. As the microstructure becomes increasingly fine, widi grain sizes approaching 100Å, the unique characterization capabilities of transmission electron microscopy (TEM) have become indispensable to the analysis of such thin film magnetic media.Films were deposited at 225°C, on two NiP plated Al substrates, one polished, and one circumferentially textured with a mean roughness of 55Å. Three layers, a 750Å chromium underlayer, a 600Å layer of magnetic alloy of composition Co84Cr14Ta2, and a 300Å amorphous carbon overcoat were then sputter deposited using a dc magnetron system at a power of 1kW, in a chamber evacuated below 10-6 torr and filled to 12μm Ar pressure. The textured medium is presently used in industry owing to its high coercivity, Hc, and relatively low noise. One important feature is that the coercivity in the circumferential read/write direction is significandy higher than that in the radial direction.

Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

1985 ◽  
Vol 43 ◽  
pp. 364-365
Author(s):  
K.M. Hones ◽  
P. Sheldon ◽  
B.G. Yacobi ◽  
A. Mason
Keyword(s):  
High Efficiency ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Growth Conditions ◽  
Nonradiative Recombination ◽  
Device Structure ◽  
Si Substrates ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

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