Aromaticity, quantum multimolecular polyhedra, and quantum QSPR fundamental equation

2015 ◽  
Vol 37 (1) ◽  
pp. 78-82 ◽  
Author(s):  
Ramon Carbó-Dorca
Keyword(s):  
Fundamental Equation ◽  
Quantum Qspr ◽  
Quantum Multimolecular Polyhedra

Molecular Spaces Quantum Quantitative Structure-Properties Relations (QQSPR)

2016 ◽  
Vol 1 (2) ◽  
pp. 1-22
Author(s):  
Ramon Carbó-Dorca ◽  
Silvia González
Keyword(s):  
Fundamental Equation ◽  
Space Structure ◽  
Molecular Properties ◽  
Quantum Mechanical ◽  
Density Functions ◽  
Quantitative Structure ◽  
Expectation Values ◽  
Quantum Qspr ◽  
Structure Properties

Quantum QSPR can be described as a set of procedures, which can be obtained from molecular space structure, where quantum (multi)molecular polyhedra (QMP) can be defined. The collective vectors, which can be described characteristic of a given QMP and their condensed scalar values, can be used in turn to construct Hermitian QQSPR operators, which can be further employed to obtain expectation values of complex molecular properties. The linear QQSPR fundamental equation constructed from this quantum mechanical idea is able to fundament, not only an algorithm capable to obtain estimates of unknown molecular properties from the knowledge of quantum mechanical density functions, but also from the empirical, classical numerical description of molecular sets.

Speed-of-Sound Measurements and a Fundamental Equation of State for Propylene Glycol

2021 ◽  
Vol 50 (2) ◽  
pp. 023105
Author(s):  
Tim Eisenbach ◽  
Christian Scholz ◽  
Roland Span ◽  
Diego Cristancho ◽  
Eric W. Lemmon ◽  
...  
Keyword(s):  
Equation Of State ◽  
Propylene Glycol ◽  
Speed Of Sound ◽  
Fundamental Equation ◽  
Fundamental Equation Of State

An appraisal of numerical integration methods as applied to strong-motion data

1943 ◽  
Vol 33 (1) ◽  
pp. 21-60
Author(s):  
Frank Neumann
Keyword(s):  
Numerical Integration ◽  
Fundamental Equation ◽  
Shaking Table ◽  
Mathematical Treatment ◽  
Torsion Pendulum ◽  
Massachusetts Institute Of Technology ◽  
Shaking Table Tests ◽  
Complex Type ◽  
Double Integration ◽  
Table Motion

Abstract Summary Accuracy of displacement curves computed from accelerograph records by numerical double integration.—The following results were obtained from Coast and Geodetic Survey accelerograph records in shaking-table tests made at the Massachusetts Institute of Technology: Accelerograph performance.—The preceding paragraphs show that the pivot type of accelerometer now in use is satisfactory from the engineering viewpoint and that wave forms in terms of displacement can be satisfactorily computed for all but the longer-period waves. In transferring from the quadrifilar type of pendulum suspension to the pivot type to obtain a sturdier and more readily adjustable instrument, some sacrifice was made in accuracy of performance, but it is not serious. Although the pivot suspensions embody the highest quality of workmanship, they nevertheless undergo (when recording an earthquake) a certain amount of minute shifting, and this is greatly amplified in the double-integration process. This necessitates a high standard of servicing, and some adjusting in the mathematical treatment. The present drum speed of 1 cm/sec. seems satisfactory enough for the present. Any expected increase in the accuracy of computed displacements through opening up the time scale would, at the present time, be nullified by errors resulting from pendulum instability. A more immediate advantage would be greater ease in disentangling overlapping curves and extrapolating those which go off the sheet entirely. Reduction of accelerometer sensitivity solves this problem, which in practice is serious. Errors due to imperfections in the uniformity of the paper speed are of secondary importance. A test with one accelerometer recording a 45° component of the true table motion indicated that accelerographs correctly record the components of an impressed motion according to theoretical expectations, but obviously within the limits of normal instrumental performance. Numerical integration.—The shaking-table tests prove the validity of the basis on which axis adjustments are made when one is double-integrating an accelerograph record to obtain displacement. All shaking-table motions were computed from the recorded acceleration (or seismograph) records without advance knowledge of the table motion, and no preliminary tests were made to investigate possible sources of error. They demonstrated that even permanent displacements can be detected under favorable conditions; but with most accelerograph records this is problematical. In the accelerometer tests a systematic error was found to be due to heat distortion of the accelerogram in the lantern enlargement process. After the tests, a specially designed mechanical enlarging apparatus eliminated this and incorporated many other practical advantages. With respect to the more complex type of shaking-table accelerograph record, it was found that a time increment five times larger than the 1/30 second actually used would have given practically the same result in computation of the shaking-table displacement. This means that the time employed on the summation processes could safely have been reduced to one-fifth that required for the smaller increment. Caution is necessary, however, if the velocity curve is to be used for period investigations or other special purposes, as the increment must be small enough to outline correctly all important waves. Time increments between 0.07 and 0.15 second would appear to serve satisfactorily for active types of accelerograms. The effect of omitting the first two terms of the fundamental equation of pendulum motion was determined for a complex type of shaking-table motion and was found to be rather insignificant. Current practice assumes that an accelerometer registers true acceleration for very rapid motions as well as for the slower ones, but there are limitations. The effect would be even less if the accelerometer pendulum period should be shortened, a step which would also effect a desirable decrease in sensitivity. The time required to process accelerograms is not prohibitive. The actual summation processes require less time than enlarging and scaling the acceleration curves and constructing the computed curves, but a considerable amount of additional work is usually involved because of adjustments and recomputations made necessary by accelerometer-pendulum zero shifts. Displacement with a torsion-pendulum analyzer.—An actual earthquake accelerograph record was used to test the practicability of determining displacement by making an experimental torsion pendulum simulate the response of a long-period seismograph pendulum. A comparison between the pendulum curve and the displacement computed by double-integrating the accelerograph record revealed a difference which was only half the smallest displacement error found in the M.I.T. shaking-table tests. Pendulum results, however, are subject to some uncertainty at the beginning of the motion, because acceleration records lose a certain amount of the initial ground motion in getting started. They “smooth out” rather than correct the effects of unstable accelerometer pendulums. The torsion pendulum, nevertheless, is well suited to play an important part in the practical solution of seismological as well as engineering problems.

Comparison of spectral methods for the evaluation of Stokes integral  

2021 ◽  
Author(s):  
Avadh Bihari Narayan ◽  
Ashutosh Tiwari ◽  
Govind Sharma ◽  
Balaji Devaraju ◽  
Onkar Dikshit
Keyword(s):  
Boundary Value Problems ◽  
Numerical Integration ◽  
Spectral Methods ◽  
Boundary Value ◽  
Fundamental Equation ◽  
Computation Time ◽  
Spherical Approximation ◽  
Integration Technique ◽  
Gravity Measurements ◽  
Stokes Integral

<p>The spherical approximation of the fundamental equation of geodesy defines the boundary value problems. Stokes’s integral provides the solution of boundary value problems that enables the computation of geoid from the properly reduced gravity measurements to the geoid. The stokes integral can be evaluated by brute-force numerical integration, spectral methods, and least-squares collocation. There is a trade-off between computation time and accuracy when we chose numerical integration technique or any spectral method. This research will compare time complexity and the accuracy of different spectral methods (1D-FFT, 2D-FFT, Multi-band FFT) and numerical integration technique for the region in the lower Himalaya, around Nainital, Uttarakhand, India. </p>

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