Calculation of the vacuum pressure gradient in field emission displays

The usual design of field-emission displays (FEDs) often results in high vacuum pressure gradients inside the glass plates of the device, and this is the main limitation to the widespread availability of large area FEDs. In this paper, we perform theoretical calculations using the finite element method for determining the pressure distributions in several pumping configurations, including a new FED configuration known as porous FED or pFED. The approach here is capable of clarifying the design issues influencing the final pressure relevant to the field-emission display devices. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Model to design drip hose lateral line using two spacing between emitters

The use of non-pressure compensating drip hose in horticultural and annual cycle fruits is growing in Brazil. In this case, the challenge for designers is getting longer lateral lines with high values of uniformity. The objective of this study was to develop a model to design longer lateral lines using non-pressure compensating drip hose. Using the developed model, the hypotheses to be evaluated were: a) the use of two different spacing between emitters in the same lateral line allows longer length; b) it is possible to get longer lateral lines using high values of pressure variation in the lateral lines since the distribution uniformity stays below allowable limits. A computer program was developed in Delphi based on the model developed and it is able to design lateral lines in level using non-pressure compensating drip hose. The input data are: desired distribution uniformity (DU); initial and final pressure in the lateral line; coefficients of relationship between emitter discharge and pressure head; hose internal diameter; pipe cross-sectional area with the dripper; and roughness coefficient for the Hazen-Williams equation. The program allows calculate the lateral line length with three possibilities: selecting two spacing between emitters and defining the exchange point; using two pre-established spacing between emitters and calculating the length of each section with different spacing; using one emitter spacing. Results showed that the use of two sections with different spacing between drippers in the lateral line didn't allow longer length but got better uniformity when compared with lateral line with one spacing between emitters. The adoption of two spacing increased the flow rate per meter in the final section which represented approximately 80% of the lateral line total length and this justifies their use. The software allowed DU above 90% with pressure head variation of 40% and the use of two spacing between emitters. The developed model/software showed to be accurate, easy to handle and useful for lateral line design using non-pressure compensating drip hose.

Development of new concepts in low tire pressure warning devices. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Feasibility of automating truck tire pressure data collection. Final report.

Texas State Department of Highways and Public Transportation, Austin

Proof pressure evaluation of worn passenger car tire carcasses. Final report.

National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

Procedures for controlling the effect of increased tire pressure on asphalt concrete pavement damage. Final report.

Oregon Department of Transportation, Salem

Effects of load, inflation pressure and tire deflection on truck tire noise levels. Final report.

Transportation Department, Office of Noise Abatement, Washington, D.C.

Comfort and convenience specifications for safety belts: shoulder belt fit, pressure and pullout forces. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Pressure tests in flood-control conduit, Melvern Dam, Kansas : final report /

Issued May 1977.

Piezoelectric polymer transducers for dynamic pressure measurements. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Pressure effects on worn passenger car tire carcasses. Final report.

Transportation Systems Center, Cambridge, Mass.

Pressure gradient effects on supersonic boundary layer turbulence : final report /

"Carried out by the Fluid Mechanics Section of the Aeronutronic Division of the Ford Aerospace & Communications Corporation."