6. Thomas Scanlon and the Desire for Reasonable Agreement

2018 ◽  
pp. 78-89
2020 ◽  
Author(s):  
Daniel Koch ◽  
Sergei Manzhos

<p></p><p>The generalized gradient approximation (GGA) often fails to correctly describe the electronic structure and thermochemistry of transition metal oxides and is commonly improved using an inexpensive correction term with a scaling parameter <i>U</i>. We tune <i>U</i> to reproduce experimental vanadium oxide redox energetics with a localized basis and a GGA functional. We find the value for <i>U</i> to be significantly lower than what is generally reported with plane-wave bases, with the uncorrected GGA results being in reasonable agreement with experiments. We use this computational setup to calculate interstitial and substitutional <a>insertion energies of main group metals in vanadium pentoxide</a> and find <a>interstitial doping to be thermodynamically favored</a>.</p><p></p>


2001 ◽  
Vol 1 (5-6) ◽  
pp. 215-220
Author(s):  
A. Gillighan ◽  
S.J. Judd ◽  
R. Eyres

The efficacy of ultrafiltration (UF) and microfiltration (MF) membranes was assessed for the concentration of actual waterworks sludges using crossflow tubular membranes operated at constant trans-membrane pressure. The MF membrane gave higher initial fluxes than the UF membrane but after 10 min of filtration the flux value and its decline tended to be very similar for both membranes operating under the same conditions. All membranes gave permeate product water of &lt;0.2 NTU and &lt;100ppb coagulant at all times. For both membranes mechanical cleaning, with sponge balls, was at least as effective as acid chemical cleaning, indicating that no significant permanent internal fouling occurred for these membrane materials. Hydraulic resistance data indicated a significant difference in the dynamic layer resistance between the two membranes. Whilst the UF membrane had a hydraulic resistance 3.7 times that of the MF membrane, the dynamic layer formed on the UF membrane during operation displayed a maximum hydraulic resistance almost nine times lower than that of the MF membrane operating under the same conditions. Correlation of cake resistance R versus feed solids concentration C for all the data generated for t&gt;0 demonstrated reasonable agreement with the expression R∝ca where a=0.37 in the current study. This trend has been recorded in previous reported studies, a varying between 0.33 and 0.62 depending on sludge dewaterability.


Clay Minerals ◽  
1990 ◽  
Vol 25 (2) ◽  
pp. 161-179 ◽  
Author(s):  
H. C. B. Hansen ◽  
R. M. Taylor

AbstractTwo-layered Fe(III)-M(II) hydroxy carbonates (M(II) = Ni or Mg) have been synthesized by induced hydrolysis using controlled air oxidation of an aqueous Fe(II)-M(II) mixture (M(II)/Fe(II) ratio >3) at a pH below which the hydroxide of the M(II) cation precipitates. The crystalline, homogeneous product can be a single phase consisting of very thin circular to hexagonal plates (0·2–0·8 µm diam.). For synthetic reevesite (Ni(II)-Fe(III) hydroxy carbonate), stable spherular aggregates are formed. The well crystallized products have an M(II)/Fe(III) ratio of about two. However, by varying the pH, the initial M(II)-Fe(III) ratio and the oxidation rate, the M(II)/Fe(III) ratio in the product and its crystallinity can be varied. The derived formulae are in reasonable agreement with the known composition of pyroaurite-type compounds. Possible synthesis pathways are discussed. The ability to control some physical and morphological features of the products indicates that the synthesis technique could prove advantageous in the preparation of certain catalyst precursors.


2002 ◽  
Vol 12 ◽  
pp. 676-679
Author(s):  
Ruth C. Peterson

AbstractRecent results are reviewed for two methods of luminosity calibration based on high-resolution spectroscopy. The first relies onTeff/loggdeterminations from model-atmosphere analyses based on high-resolution spectra. This method is physically well founded but operationally demanding, and requires advance knowledge of stellar mass. The second, W-B, stems from the empirical relationship between luminosity and the width of chromospheric emission lines first established by Wilson and Bappu. Its physical basis is only partially understood, however, and the calibration depends on stellar metallicity and on the choice of lines.BothTeff/loggand W-B easily distinguish cool dwarfs from cool giants. Generally reasonable agreement is found between distances derived from Hipparcos parallaxes and those inferred from the loggvalues derived for nearby dwarfs with relatively well-known Hipparcos parallaxes, σ(π)/π &lt; 0.2. Constraining Hipparcos parallaxes star-by-star is not possible at present. Improvements are suggested for both approaches.


1993 ◽  
Vol 115 (4) ◽  
pp. 427-435 ◽  
Author(s):  
K. Gupta ◽  
K. D. Gupta ◽  
K. Athre

A dual rotor rig is developed and is briefly discussed. The rig is capable of simulating dynamically the two spool aeroengine, though it does not physically resemble the actual aeroengine configuration. Critical speeds, mode shape, and unbalance response are determined experimentally. An extended transfer matrix procedure in complex variables is developed for obtaining unbalance response of dual rotor system. Experimental results obtained are compared with theoretical results and are found to be in reasonable agreement.


2010 ◽  
Vol 56 (196) ◽  
pp. 333-338 ◽  
Author(s):  
Tsutomu Nakamura ◽  
Osamu Abe ◽  
Ryuhei Hashimoto ◽  
Takeshi Ohta

AbstractA new vibration apparatus for measuring the shear strength of snow has been designed and fabricated. The force applied to a snow block is calculated using Newton’s second law. Results from this apparatus concerning the dependence of the shear strength on snow density, overburden load and strain rate are in reasonable agreement with those obtained from the work of previous researchers. Snow densities ranged from 160 to 320 kg m−3. The overburden load and strain rate ranged from 1.95 × 10−1to 7.79 × 10−1kPa and 2.9 × 10−4to 9.1 × 10−3s−1respectively.


2005 ◽  
Vol 492-493 ◽  
pp. 459-464 ◽  
Author(s):  
Shin-ichiro Tsuru ◽  
Noriyuki Hayashi ◽  
Tomohiko Onoda ◽  
Yasushi Sakamoto ◽  
Masanori Hara

A new numerical method to simulate the centrifugal process of fabricating functionally graded materials (FGMs) from solid-particles/viscous-matrix mixtures is proposed, and the simulation method was successfully applied to a practical fabrication process of FGM from an alumina-fillers/epoxy-resin mixture. Gradient profiles of dielectric constant of the resultant FGM were estimated by using the proposed method and compared with the experimental ones, resulting in reasonable agreement between them. Based on the numerical results, gradient pro- files of the number density and size of the dispersed fillers were confirmed, and contribution of the filler size toward the gradient in the packing fraction was demonstrated. It is concluded that the gradient in the filler distribution can be intentionally regulated by changing not only the centrifugal conditions, but also the size distribution of the fillers.


2001 ◽  
Vol 17 (1) ◽  
pp. 51-66 ◽  
Author(s):  
Amaryta Sen

I am most grateful to Elizabeth Anderson (2000), Philip Pettit (2000) and Thomas Scanlon (2000) for making such insightful and penetrating comments on my work and the related literature. I have reason enough to be happy, having been powerfully defended in some respects and engagingly challenged in others. I must also take this opportunity of thanking Martha Nussbaum, for not only chairing the session in which these papers were presented followed by a splendid discussion (which she led), but also for taking the initiative, in the first place, to arrange the session.


1979 ◽  
Vol 46 (4) ◽  
pp. 761-766 ◽  
Author(s):  
W. C. Chin ◽  
D. P. Rizzetta

The “inverse” or “design” problem in aerodynamics, which solves for the airfoil shape that induces a prescribed chordwise surface pressure subject to additional requirements on trailing edge closure, is considered in the transonic small-disturbance limit. A new formulation for the stream function ψ is suggested which uses well-set Neumann conditions on the chordwise slit, with the degree of closure dictated by a specified jump in ψ across the downstream slit emanating from the trailing edge. The boundary-value problem is solved by a type-dependent relaxation method that automatically generates closed airfoils on convergence. Computed airfoil shapes using subcritical and supercritical pressure distributions obtained from existing finite-difference analysis codes, in the latter case, with and without shockwaves, give results in reasonable agreement with the original specified shapes, and validate the basic ideas.


1985 ◽  
Vol 107 (1) ◽  
pp. 31-36 ◽  
Author(s):  
D. Koffi ◽  
R. Gauvin ◽  
H. Yelle

Since thermoplastics are temperature-sensitive materials, heat generation in running spur gears is an important parameter. This paper presents two models for its evaluation, an exact one which considers all the parameters but needs a computer to solve the equations; then a simplified model. Both models take into account the contact outside the theoretical line of action which is the usual case with thermoplastic gears. Results for the simplified model are within reasonable agreement with the exact one.


Sign in / Sign up

Export Citation Format

Share Document