The Determination of Optimal Finite-Precision Controller Realisations Using a Global Optimisation Strategy: A Pole-Sensitivity Approach

2001 ◽  
pp. 87-104 ◽  
Author(s):  
Sheng Chen ◽  
Jun Wu
Keyword(s):  
Global Optimisation ◽  
Finite Precision ◽  
Sensitivity Approach

Sensitivity of the Human Comfort Equation and of Free Convection in a Vertical Enclosure as Examples of the Use of Global Sensitivity to Evaluate Parameter Interactions

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
A. F. Emery ◽  
M.-H. H. Wu ◽  
A. M. Mescher
Keyword(s):  
Free Convection ◽  
Human Comfort ◽  
Global Sensitivity ◽  
Sensitivity Studies ◽  
Multiple Variables ◽  
Sensitivity Approach ◽  
Parameter Interactions ◽  
Scientific Systems ◽  
Large Interaction

Many models of engineering and scientific systems involve interactions between and among the parameters, stimuli, and physical properties. The determination of the adequacy of models for predictions and for designing experiments generally involves sensitivity studies. Good designs mandate that the experiments be sensitive to the parameters sought with little interaction between them because such interaction generally confuses the estimation and reduces the precision of the estimates. For design purposes, analysts frequently want to evaluate the sensitivities of the predicted responses to specific variables, but if the variables interact it is often difficult to separate the effects. Global sensitivity is a technique by which one can evaluate the magnitude of the interactions between multiple variables. In this paper, the global sensitivity approach is applied to the human comfort equation and to free convection in a rectangular enclosure. It is found that when occupants are uncomfortable, there is little interaction and that one can predict the effects of changing several environmental conditions at once by adding the separate effects. But when occupants are comfortable, there is a large interaction and the effects cannot be treated separately. Free convective heat transfer in an enclosure is a function of the Rayleigh number Ra and the aspect ratio H/W, and the flow field changes from unicellular to multicellular as Ra increases. There is a strong interaction for H/W≤2 but little for H/W≥2.

Sensitivity of the Human Comfort Equation: An Example of the Use of Global Sensitivity to Evaluate Sensitivity Interactions

2007 ◽  
Author(s):  
A. F. Emery ◽  
MingHang H. Wu
Keyword(s):  
Physical Properties ◽  
Environmental Conditions ◽  
Human Comfort ◽  
Global Sensitivity ◽  
Sensitivity Studies ◽  
Multiple Variables ◽  
Sensitivity Approach ◽  
Scientific Systems ◽  
Large Interaction

Many models of engineering and scientific systems involve interactions between and among the parameters, stimuli, and physical properties. The determination of the adequacy of models for predictions and for designing experiments generally involves sensitivity studies. This is particularly true for experiments by which properties are to be estimated. Good designs mandate that the experiments be sensitive to the parameters sought with little interaction between them because such interaction generally confuse the estimation and reduce the precision of the estimates. For design purposes, analysts frequently want to evaluate the sensitivities of the predicted responses to specific variables but it the variables interact it is often difficult to separate the effects. Global sensitivity is a technique by which one can evaluate the magnitude of the interactions between multiple variables. In this paper the global sensitivity approach is applied to the human comfort equation. The aim is twofold: 1) to demonstrate the usefulness of the global sensitivity approach, 2) to increase our understanding of how human comfort is affected by activity, clothing, and environmental conditions. It is found that when occupants are uncomfortable there is little interaction and that one can predict the effects of changing several environmental conditions at once by adding the separate effects. But when occupants are comfortable there is a large interaction and the effects cannot be treated separately.

Determination of the soil hazardous concentrations of bisphenol A using the species sensitivity approach

2018 ◽  
Vol 344 ◽  
pp. 390-397 ◽  
Author(s):  
Jin Il Kwak ◽  
Jongmin Moon ◽  
Dokyung Kim ◽  
Rongxue Cui ◽  
Youn-Joo An
Keyword(s):  
Bisphenol A ◽  
Species Sensitivity ◽  
Sensitivity Approach

scholarly journals Analysis, Evaluation and Exact Tracking of the Finite Precision Error Generated in Arbitrary Number of Multiplications

Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1199
Author(s):  
Constantin Papaodysseus ◽  
Dimitris Arabadjis ◽  
Fotios Giannopoulos ◽  
Athanasios Rafail Mamatsis ◽  
Constantinos Chalatsis
Keyword(s):  
Theoretical Analysis ◽  
Statistical Properties ◽  
General Applicability ◽  
Precision Error ◽  
Finite Precision ◽  
Novel Approach ◽  
Exact Evaluation ◽  
Error Accumulation ◽  
Accumulated Error

In the present paper, a novel approach is introduced for the study, estimation and exact tracking of the finite precision error generated and accumulated during any number of multiplications. It is shown that, as a rule, this operation is very “toxic”, in the sense that it may force the finite precision error accumulation to grow arbitrarily large, under specific conditions that are fully described here. First, an ensemble of definitions of general applicability is given for the rigorous determination of the number of erroneous digits accumulated in any quantity of an arbitrary algorithm. Next, the exact number of erroneous digits produced in a single multiplication is given as a function of the involved operands, together with formulae offering the corresponding probabilities. In case the statistical properties of these operands are known, exact evaluation of the aforementioned probabilities takes place. Subsequently, the statistical properties of the accumulated finite precision error during any number of successive multiplications are explicitly analyzed. A method for exact tracking of this accumulated error is presented, together with associated theorems. Moreover, numerous dedicated experiments are developed and the corresponding results that fully support the theoretical analysis are given. Eventually, a number of important, probable and possible applications is proposed, where all of them are based on the methodology and the results introduced in the present work. The proposed methodology is expandable, so as to tackle the round-off error analysis in all arithmetic operations.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

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