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Full-Text Articles in Engineering

On The Liquid Flow Distribution In Trickle-Bed Reactors, Rodney O. Fox Dec 1987

On The Liquid Flow Distribution In Trickle-Bed Reactors, Rodney O. Fox

Rodney O. Fox

The previous analytical expression for the liquid flow distribution in trickle beds found by maximizing the so-called configurational entropy is reviewed, and a novel derivation is offered, more closely modeling data found in the literature. The novel distribution is an analytical expression describing the liquid flow distribution recently found by employing a Monte Carlo simulation of the very large lattice model (VLLM), thus reducing this computationally time-consuming procedure to a simple equation. The resultant distribution is a function of the total flow rate through the trickle bed, the bed permeability as expressed by the number of open channels through the …


Theoretical Study Of The Environmental Effects On The Hyperfine Fields Of Ni And Fe In Ni0.75fe0.25, H. Ebert, H. Winter, B. Gyorffy, Duane D. Johnson, F. J. Pinski Nov 1987

Theoretical Study Of The Environmental Effects On The Hyperfine Fields Of Ni And Fe In Ni0.75fe0.25, H. Ebert, H. Winter, B. Gyorffy, Duane D. Johnson, F. J. Pinski

Duane D. Johnson

The dependence of the hyperfine fields Bhf of Ni and Fe in Ni0.75Fe0.25 on the surrounding atomic configuration has been studied by performing charge selfconsistent 6 shell-cluster Korringa-Kohn-Rostoker Coherent Potential Approximation (KKR-CPA) bandstructure calculations. By replacing the CPA- scatterers in the various shells around the central atom by Ni - or Fe-atoms, respectively, it could be shown that the hyperfine fields vary linearly with the number of Fe-atoms within a given shell and that the changes of Bhf due to simultaneous changes of the atomic configurations of different shells are additive. The changes of the hyperfine fields upon ordering of …


Post-Effect Of Ammonia On Energetics Of Laying Hens At High Temperatures, Hongwei Xin, James A. Deshazer, M. M. Beck Jun 1987

Post-Effect Of Ammonia On Energetics Of Laying Hens At High Temperatures, Hongwei Xin, James A. Deshazer, M. M. Beck

Hongwei Xin

Leghorn layers were monitored for heat loss, feed intake, egg production and respiratory rate at various environmental temperatures (TJ after first being exposed to aerial ammonia (NH3). The initial exposure was to 10 or 60 ppm NH3 at a T, of 25 °C for 30 days to simulate a winter environmental condition in a poultry facility. Hens were then allowed to recover in an environment of 5 ppm of NH3 at a T^ of 22 °C for seven days to simulate a spring environmental condition. Birds were then placed individually in a partitional calorimeter free of NH3 at 25, 29, …


The Further Geometry Of Grain Boundaries In Hexagonal Close-Packed Metals, Fu-Rong Chen, Alexander H. King Jan 1987

The Further Geometry Of Grain Boundaries In Hexagonal Close-Packed Metals, Fu-Rong Chen, Alexander H. King

Alexander H. King

A technique is given for finding partial DSC vectors appropriate to crystals with more than one atom per lattice site. The DSC lattice is made up of vectors that represent displacements of one crystal with respect to the other that leave the boundary structure shifted, but not complete. A new, rapid method for finding the step vectors associated with perfect DSC dislocations is described. Partial DSC vectors and step vectors for perfect DSC dislocations in hexagonal close-packed crystals are determined. The availability of reactions between lattice partial dislocations and grain boundaries in hexagonal close-packed crystals is also assessed.


Calculated High‐Pressure Properties Of Solid Acetylene And Possible Polymerization Paths, Richard Alan Lesar Jan 1987

Calculated High‐Pressure Properties Of Solid Acetylene And Possible Polymerization Paths, Richard Alan Lesar

Richard Alan Lesar

Results of theoretical calculations at 0 K on the two known structures of solid acetylene using the modified Gordon–Kim plus damped dispersion model are reported. The lattice energy of the low temperature C m c astructure is compared to that of the high temperature P a3 structure at zero pressure and found to be slightly less stable, though a very small pressure (about 0.25 kbar) stabilizes the C m c astructure relative to the P a3 structure. Agreement between the experimental structure and energy for the C m c astructure and our present results is good. Structural properties of the …


Ultrasonic Nondestructive Evaluation Of Fibre-Reinforced Composite Materials - A Review, Vikram K. Kinra, Vinay Dayal Jan 1987

Ultrasonic Nondestructive Evaluation Of Fibre-Reinforced Composite Materials - A Review, Vikram K. Kinra, Vinay Dayal

Vinay Dayal

This paper reviews various ultrasonic nondestructive evaluation techniques applicable to fibre-reinforced composites. The techniques are briefly described and key references are cited. Methods to evaluate the reduced stiffness of composites due to micro-damage are described. Results show that for composites through-the-thickness attenuation increases and stiffness does not change due to transverse cracks, but in-plane stiffness and attenuation changes are substantial and can be measured by the Lamb wave techniques.


Vibrational Frequency Shifts In Dense Molecular Fluids, Richard Alan Lesar Jan 1987

Vibrational Frequency Shifts In Dense Molecular Fluids, Richard Alan Lesar

Richard Alan Lesar

A theory is presented for calculating the bond length and vibrational frequency shifts in dense molecular fluids. We combine equation‐of‐state calculations based on the effective spherical potentials of Shaw, Johnson, and co‐workers with a simple model for the interactions of a molecule with the surrounding fluid. The repulsive interactions are approximated with the hard‐sphere model of Schweizer and Chandler. We extend their model by including an improved treatment of the long‐range attractive interactions and the centrifugal forces. We apply this model to fluid nitrogen and compare with static and shock wave experimental frequency shifts, as well as computer simulation data, …


Interaction Between Magnetic And Compositional Order In Ni‐Rich Ni C Fe1−C Alloys (Invited), J. B. Staunton, Duane D. Johnson, B. L. Gyorffy Jan 1987

Interaction Between Magnetic And Compositional Order In Ni‐Rich Ni C Fe1−C Alloys (Invited), J. B. Staunton, Duane D. Johnson, B. L. Gyorffy

Duane D. Johnson

We have developed a first‐principles electronic theory of concentration fluctuations in spin polarized binary alloys. It is a mean field theory of the state of compositional order and it is based on the local spin density (LSD) approximation for describing the electrons. The usual averages over the statistical mechanical ensemble are carried out with the aid of the self‐consistent Korringe–Kohn–Rostoker coherent‐potential approximation (SCF‐KKR‐CPA). To illustrate the main consequences of the theory we study the compositional short‐range order in the Ni c Fe1−c alloy system. We find that the ordering energy is almost entirely of magnetic origin.