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334 results on '"Pfeffer, Robert"'

21. Electromagnetic threats to he national power grid

Author

Pfeffer, Robert

Subjects
United States. House of Representatives, Chemicals, plastics and rubber industries, Military and naval science, Federal Power Act
Abstract

The NPG is now so fundamental to U.S. infrastructure that, without it, the national economy would collapse and the health of the civilian population would be at risk. This scenario [...]

Published
2010

22. DODI 3222.3 and Army system HEMP survivability: an update

Author

Pfeffer, Robert A.

Subjects
United States. Department of Defense, United States. Army, Combat survivability (Military engineering) -- Military aspects, Weapons of mass destruction -- Military aspects, Chemicals, plastics and rubber industries, Military and naval science
Abstract

[ILLUSTRATION OMITTED] Note. A previous article entitled 'DODI 3222.3 and Army System HEMP Survivability' was published in the Combating WMD Journal in 2007. (1) Since then, several Department of Defense [...]

Published
2009

30. The argument for a unified approach to non-ionizing radiation protection

Author

Perala, Rodney A., Pfeffer, Robert A., and Rigden, Gregory J.

Subjects
Military electronics -- Design and construction, Nonionizing radiation -- Evaluation, Electronic equipment and supplies, Effect of radiation on -- Research, Business, Electronics, Electronics and electrical industries
Abstract

New generation military equipment will be required to operate in severe electromagnetic environments containing non-ionizing frequencies from a variety of sources which can possibly cause the failure of onboard electronic equipment. It is suggested that a combination of zonal shielding and penetration protection can harden electronic equipment against non-ionizing radiation from both hostile and non-hostile sources.

Published
1993

39. Directional drilling on construction section SBT3.1 – the challenge of drilling speed and accuracy.

Author

Pfeffer, Robert, Rohm, Paul, and Oppitz, David

Subjects
*DIRECTIONAL drilling, *FAULT zones, *SPEED, *BOREHOLES, *HORIZONTAL wells, *DRAINAGE
Abstract

The Semmering Base Tunnel is being built by Austrian Federal Railways as part of the upgrading of the southern railway line. On contract SBT3.1, Züblin Spezialtiefbau Ges.m.b.H. was employed to undertake slope stabilization, piles dia. 1,500 mm embedded into the rock, as well as vertical and horizontal boreholes in the fault zones of Semmering. Due to the high requirements on drilling speed and accuracy of the boreholes, they were drilled as directional drilling with a hydraulic down‐the‐hole hammer. The vertical holes were used to install sleeve pipes for grouting works for the shaft Sommerau 2. The horizontal holes, also planned for the inclusion of sleeve pipes for grouting works, were used after on‐site rescheduling during the project for exploration and drainage of the rock mass. The drilling and survey data were subject to continual and thorough review to increase the efficiency of each control operation. [ABSTRACT FROM AUTHOR]

Published
2019
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50. The influence of viscosity on the strength of an axially strained pendular liquid bridge

Author

Pfeffer Robert, Bryan J. Ennis, I Tardos Gabriel, and Jianlan Li

Subjects
Oscillation, Chemistry, Applied Mathematics, General Chemical Engineering, Reynolds number, General Chemistry, Mechanics, Lubrication theory, Industrial and Manufacturing Engineering, Capillary number, symbols.namesake, Viscosity, Classical mechanics, symbols, Deformation (engineering), Axial symmetry, Added mass
Abstract

Pendular liquid bridges between two relatively moving solid particles (dynamic bridges) occur extensively throughout the powder technology industry, with a typical example being binder granulation. By means of a sensitive linear voltage differential force tranducer, the influence of viscosity on the strength of an axially, periodically strained pendular bridge was investigated where bridge strength is defined as the maximum interparticle force developed during one complete sphere oscillation. The relative importance of the theoretically derived dimensionless groups governing bridge strength is experimentally established for systems exhibiting complete solid—liquid wettability. A simplified solution of dynamic bridge strength based on the superposition of lubrication theory and circular approximation is presented. For a small gap distance with sufficient bridge volume and in the limit of small Reynolds number, a good agreement between the experimental and present theoretical axial force response is observed, indicating the importance of the capillary number Ca in determining pendular bridge strength. The present quasi-static solution is zeroeth-order in Ca and gap distance, and is expected to break down with increasing local inertial effects. Such inertial effects are governed by a modified Bond number. In the limit of low Ca , they lead to an increase in bridge strength due to an added mass effect, whereas in the limit of high Ca , they lead to a reduced, shifted force response due to an insufficient rate of vorticity propagation. Under industrially relevant conditions, the strength of the dynamic bridge was observed to exceed the static by over an order of magnitude. Since a significant number of powder processes such as granulation are not static in nature, viscous interactions between particles should be considered whenever a liquid interstitial phase is present.

Published
1990

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