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Articles 1 - 11 of 11

Full-Text Articles in Engineering

Polymer Research In Austria. I: Introduction And The Facilities, Otto Vogl, Josef Schurz, Bernd Thrattnigg, Klaus Hummel, Wolfgang Daimler, Klaus Lederer Dec 1991

Polymer Research In Austria. I: Introduction And The Facilities, Otto Vogl, Josef Schurz, Bernd Thrattnigg, Klaus Hummel, Wolfgang Daimler, Klaus Lederer

Otto Vogl

No abstract provided.


Japan-U.S. Seminar On Polymer Synthesis, Otto Vogl, Hiroyuki Nishide Dec 1991

Japan-U.S. Seminar On Polymer Synthesis, Otto Vogl, Hiroyuki Nishide

Otto Vogl

No abstract provided.


First-Principles Study Of Phase Stability In Cu-Zn Substitutional Alloys, P. E. A. Turchi, M. Sluiter, F. J. Pinski, Duane D. Johnson, D. M. Nicholson, G. M. Stocks, J. B. Staunton Sep 1991

First-Principles Study Of Phase Stability In Cu-Zn Substitutional Alloys, P. E. A. Turchi, M. Sluiter, F. J. Pinski, Duane D. Johnson, D. M. Nicholson, G. M. Stocks, J. B. Staunton

Duane D. Johnson

A parameter-free approach to phase stability in Cu-Zn substitutional alloys is shown to describe order-disorder phenomena and structural transformations with remarkable accuracy. The method is based on a multiple-scattering description of the electronic structure properties of the random alloy. Configurational order is treated within the generalized perturbation method and the concentration-functional theory. Thermodynamical properties of α and β brasses are derived from the cluster variation method. This advanced scheme is of general validity and is expected to yield similarly accurate results for other Hume-Rothery alloys.


Interpretation Issues In Force Microscopy, Nancy Burnham, Richard Colton, Hubert Pollock Jun 1991

Interpretation Issues In Force Microscopy, Nancy Burnham, Richard Colton, Hubert Pollock

Nancy A. Burnham

In this paper, we will discuss force microscopy (FM) and its potential for determining mechanical properties of thin films. We will introduce the basic principles of FM, and demonstrate how FM can be used to determine materials properties as well as image surface topography, both with nanonewton or sub‐nanonewton force resolution and sub‐nanometer position resolution. As FM is still a new field, not all of the questions concerning interpretation have been fully answered. We will elucidate four current issues that must be resolved before the full potential of FM can be realized. They are: (1) the role of water vapor …


Setting Time Effects On Bentonite Water-Well Annulus Seals, Fred L. Ogden Jun 1991

Setting Time Effects On Bentonite Water-Well Annulus Seals, Fred L. Ogden

Fred L. Ogden

Shear strength tests are conducted in a model of a water well on four, commercially available, granular bentonite well sealing products. The time dependency of annulus seal shear strength and resistance to piping is examined. Dry bentonite samples are placed through water in the annular space between the casing and borehole and allowed to set for a specified time. Pressure is applied at a constant rate to one end of the clay seal until shear or piping failure occurs. Pressure and seal displacement data are recorded on a digital data acquisition system. Annulus seal strength and resistance to piping increase …


Transport Processes And Traveling Waves In Systems With Local Nonequilibrium, Sergey Sobolev Mar 1991

Transport Processes And Traveling Waves In Systems With Local Nonequilibrium, Sergey Sobolev

Sergey Sobolev

No abstract provided.


Origins Of Compositional Order In Nipt Alloys, F. J. Pinski, B. Ginatempo, Duane D. Johnson, J. B. Staunton, G. M. Stocks, B. L. Gyorffy Feb 1991

Origins Of Compositional Order In Nipt Alloys, F. J. Pinski, B. Ginatempo, Duane D. Johnson, J. B. Staunton, G. M. Stocks, B. L. Gyorffy

Duane D. Johnson

We investigate the cause of compositional ordering in fcc Ni0.50Pt0.50 on the basis of a first-principles theory of electronic structure and finite-temperature concentration fluctuations. We treat the size effect, electronegativity, and band filling on an equal footing and find that the first of these dominates, leading to L10 ordering in agreement with experiment. An electronic origin is given for the metallurgical ‘‘rule of thumb’’ that alloys comprised of big atoms and little atoms tend to order into simple stuctures.


The Interaction Between Dislocations And Intergranular Cracks, H. Zhang, Alexander H. King, R. Thomson Feb 1991

The Interaction Between Dislocations And Intergranular Cracks, H. Zhang, Alexander H. King, R. Thomson

Alexander H. King

The elastic interactions of dislocations and intergranular cracks in isotropic materials have been studied. In the first part of the paper, a model based on the Rice–Thomson theory is established under which the conditions for dislocation emission and crack propagation can be described in terms of an emission surface, cleavage surface, and loading line in the local k-space associated with a mixed mode intergranular crack. For a given crack, the local k-field changes with the emission of dislocations from the crack tip, which alters the balance of cleavage and emission. In the second part, we present experimental results of in …


Optimering Van Koagulasie En Flokkulasie In Die Herwinning Van Koelwater Uit Oliesintese-Afvalwater, Johannes Van Leeuwen, P. Wille Jan 1991

Optimering Van Koagulasie En Flokkulasie In Die Herwinning Van Koelwater Uit Oliesintese-Afvalwater, Johannes Van Leeuwen, P. Wille

Johannes van Leeuwen

The activated sludge process, which is used in the purification of an oil synthesis effiuent, produces an effiuent which is high in turbidity. The water also contains a lot of dispersed bacterial growth which is not removed during sedimentation. Flocculation is essential to remove these materials. The average diameter of the colloids was found to be 0,92/'m. The zeta potential of the colloids was determined in an attempt to correlate it to the amount of flocculant required. The value was relatively constant at -13,88 mV, which indicates that a cationic·coagulant was required. The required dosage to achieve clarification by means …


The Slater–Pauling Curve: First Principles Calculations Of The Moments Of Fe1 − C Ni C And V1 − C Fe C, Duane Johnson, F. Pinski, J. Staunton Jan 1991

The Slater–Pauling Curve: First Principles Calculations Of The Moments Of Fe1 − C Ni C And V1 − C Fe C, Duane Johnson, F. Pinski, J. Staunton

Duane D. Johnson

We have performed calculations of the electronic structure of the random substitutional alloys Fe1−c Ni c and V1−c Fe c using the spin‐polarized, self‐consistent Korringa–Kohn–Rostoker coherent‐potential approximation (KKR‐CPA) method. This is a first principles method based on spin density functionaltheory and a local spin density approximation for the exchange and correlation functional. For fcc Fe1−c Ni c , a range of volumes were considered for 0.25


72. Professor Cristofor I. Simionescu On His 70th Birthday, Otto Vogl, Ioan I. Negulescu Jan 1991

72. Professor Cristofor I. Simionescu On His 70th Birthday, Otto Vogl, Ioan I. Negulescu

Otto Vogl

No abstract provided.