scholarly journals Dynamic linear adsorption with solid adsorbent material

2021 ◽  
pp. 46-52
Author(s):  
V.L. Poliakov
Keyword(s):  
Bound States ◽  
Input Data ◽  
Physical Adsorption ◽  
Aqueous Suspension ◽  
Mathematical Problem ◽  
Elementary Functions ◽  
Solid Adsorbent ◽  
Time Period ◽  
Constant Rate ◽  
Diffusion Transfer

A mathematical problem of linear physical adsorption of a dissolved impurity is formulated, by consider-ing its diffusion transfer during the filtration of an aqueous suspension through a uniform adsorbent bed at a constant rate. By averaging the impurity concentrations in the free and bound states over an arbi-trary time period, an approximate solution of the problem is obtained, which is only expressed in terms of the elementary functions. On its basis, it is proposed to calculate the rational duration of the filter run. The solution is discussed and illustrated with a number of examples with typical input data.

Confidence-Based Method for Reliability-Based Design Optimization

2014 ◽  
Author(s):  
Hyunkyoo Cho ◽  
K. K. Choi ◽  
David Lamb
Keyword(s):  
Design Optimization ◽  
Confidence Level ◽  
Probabilistic Model ◽  
Input Data ◽  
Mathematical Problem ◽  
Design Sensitivity ◽  
Conditional Probabilities ◽  
Probabilistic Constraint ◽  
Reliability Based Design Optimization ◽  
Reliability Based Design

An accurate input probabilistic model is necessary to obtain a trustworthy result in the reliability analysis and the reliability-based design optimization (RBDO). However, the accurate input probabilistic model is not always available. Very often only insufficient input data are available in practical engineering problems. When only the limited input data are provided, uncertainty is induced in the input probabilistic model and this uncertainty propagates to the reliability output which is defined as the probability of failure. Then, the confidence level of the reliability output will decrease. To resolve this problem, the reliability output is considered to have a probability distribution in this paper. The probability of the reliability output is obtained as a combination of consecutive conditional probabilities of input distribution type and parameters using Bayesian approach. The conditional probabilities that are obtained under certain assumptions and Monte Carlo simulation (MCS) method is used to calculate the probability of the reliability output. Using the probability of the reliability output as constraint, a confidence-based RBDO (C-RBDO) problem is formulated. In the new probabilistic constraint of the C-RBDO formulation, two threshold values of the target reliability output and the target confidence level are used. For effective C-RBDO process, the design sensitivity of the new probabilistic constraint is derived. The C-RBDO is performed for a mathematical problem with different numbers of input data and the result shows that C-RBDO optimum designs incorporate appropriate conservativeness according to the given input data.

A Winter Weather Index for Estimating Winter Roadway Maintenance Costs in the Midwest

2004 ◽  
Vol 43 (11) ◽  
pp. 1783-1790 ◽  
Author(s):  
Craig G. Carmichael ◽  
William A. Gallus ◽  
Bradley R. Temeyer ◽  
Mark K. Bryden
Keyword(s):  
Neural Network ◽  
Input Data ◽  
Department Of Transportation ◽  
Climate Data ◽  
Winter Weather ◽  
Weather Index ◽  
The Neural Network ◽  
Time Period ◽  
Regression Techniques ◽  
Better Than

Abstract Winter roadway maintenance budget data for the state of Iowa have been combined with available climate data for a 6-yr period to create a winter weather index that provides a useful assessment of winter severity. The weather index can be combined with measures of transportation department infrastructure within a region to estimate expenses for a given time period in the region. The index was developed using artificial neural network techniques that are nonlinear and perceive patterns in the input data. Winter weather severity as diagnosed by the index correlates well with Iowa Department of Transportation roadway treatment expenses. The neural network–based index is shown to perform better than the Strategic Highway Research Program (SHRP) index and an index developed using linear regression techniques.

scholarly journals Reply to: Models for the in-host dynamics of malaria revisited: errors in some basic models lead to large over-estimates of growth rates

Parasitology ◽  
1998 ◽  
Vol 117 (5) ◽  
pp. 409-410 ◽  
Author(s):  
M. B. GRAVENOR ◽  
A. L. LLOYD
Keyword(s):  
Life Span ◽  
Growth Rates ◽  
Small Variation ◽  
Average Life ◽  
Average Life Span ◽  
Modified Model ◽  
Time Period ◽  
Proposed Model ◽  
Constant Rate ◽  
Large Growth

In the accompanying manuscript Saul (1998) points out that a model of within-host malaria population dynamics (Anderson, May & Gupta, 1989) can exhibit unrealistically large growth rates. He suggests that this error can be avoided by replacing the parameter r, which is the number of merozoites produced by each parasite at schizogony, with the value ln (r)+1. This substitution does not, however, address the true underlying problem with the model, namely that whilst in reality there is small variation in the distribution of Plasmodium spp. life-spans, the use of the constant rate α assumes an exponential, and hence much more variable, distribution. This can allow the population to increase, over the time period of the average life-span (48 h in the case of Plasmodium falciparum), by factors considerably larger than r. Saul identifies this assumption as unrealistic in terms of the biology of malaria, but it is not remedied in the proposed model.Within the structure of the original model there are two ways of addressing the growth rate problem. Firstly, the ‘growth constant’ r can be replaced by the value ln (r)+1, so that if all parasites reinvade, the model increases by a factor r over 1 generation. As pointed out by Saul, this is an artificial device since it means that each parasite produces a reduced number of merozoites. Alternatively, a parasite can produce the observed number of merozoites, r, many of which do not reinvade. This is the situation in the original paper and Gravenor, McLean & Kwiatkowski (1995). In these papers the model does grow at a reasonable rate because the parameter β is estimated directly from observed growth rates. These points, however, are only an aside. Both the original and Saul's modified model can grow at the same rate and they both have the same distributional assumptions concerning parasite life-span.

Penetration, Translocation, and Metabolism of14C-Difenzoquat in Wild Oat and Barley

Weed Science ◽  
1976 ◽  
Vol 24 (4) ◽  
pp. 379-384 ◽  
Author(s):  
M. P. Sharma ◽  
W. H. Vanden Born ◽  
H. A. Friesen ◽  
D. K. McBeath
Keyword(s):  
Acetic Acid ◽  
Chromatographic Analysis ◽  
Upward Movement ◽  
Wild Oat ◽  
Triticum Vulgare ◽  
Treated Area ◽  
Time Period ◽  
Constant Rate ◽  
Applied Dose ◽  
Dichlorophenoxy Acetic Acid

Foliar penetration of14C-difenzoquat (1,2-dimethyl-3,5-diphenyl-1-H-pyrazolium), in the presence of a surfactant, into both wild oat (Avena fatuaL.) and barley (Hordeum vulgareL. ‘Conquest’), was rapid and continued at a nearly constant rate for 72 hr, the maximum time period studied; 93 and 84% of the applied dose was absorbed by the leaves of wild oat and barley, respectively. Added surfactants at 0.01% to 0.3% and high relative. humidity (RH) greatly enhanced the penetration of the herbicide into wild oat. An increase in temperature from 10 to 30 C resulted in a large increase in penetration. Commercial formulations of bromoxynil (3,5-dibromo-4-hydroxy-benzonitrile) + MCPA {[(4-chloro-O-tolyl)oxy] acetic acid} (1:1, w/w), 2,4-D[(2,4-dichlorophenoxy)acetic acid] ester and barban (4-chloro-2-butynylm-chlorocarbanilate) markedly increased the penetration of14C-difenzoquat into wild oat. Amine formulation of 2,4-D, on the other hand, had no effect on penetration. Foliarly-applied14C-difenzoquat rapidly translocated mainly in the acropetal direction. Most of the absorbed14C, however, was accumulated in the treated area and a few centimeters above the treated area. There was some basipetal movement, and 24 hr after treatment14C was detectable in the roots. Root uptake of14C-difenzoquat was very rapid, but upward movement of14C was slight, and even 24 hr after treatment most of it was retained by the roots. Chromatographic analysis of plant extracts up to 15 days after treatment with14C-difenzoquat revealed no evidence of difenzoquat metabolism by wild oat, barley, and wheat (Triticum vulgareL. ‘Thatcher’). The selective action of difenzoquat in wild oat and barley cannot be accounted for by differences in its foliar penetration, translocation, or metabolism in these species.

Hydrological modeling in data sparse environments

2021 ◽  
Author(s):  
Faizan Anwar ◽  
András Bárdossy ◽  
Jochen Seidel
Keyword(s):  
Input Data ◽  
Hydrological Modeling ◽  
Hydrological Model ◽  
Heavy Rain ◽  
Data Uncertainty ◽  
Model Parameters ◽  
Daily Data ◽  
Time Period ◽  
Main Driver ◽  
Model Parameter Uncertainty

<p>We demonstrate that in data sparse environments, model parameter uncertainty is not the only cause of concern. To get a meaningful outcome, input data uncertainty has to be taken into account as well. The procedure involved calibration of a hydrological model using recent daily data rich time period along with validation. A historical flood was simulated (after warmup) for which the input data were relatively sparse in space, namely precipitation and temperature, using the calibrated model parameters. Precipitation was assumed to be the main driver of this event. Results showed that by only using interpolated precipitation (e.g. IDW or Kriging), the magnitude and timing of the peak were incorrect, even after using very many different parameter vectors that performed equally well for the recent times. Subsequently, the model was inverted for precipitation i.e. input fields that produced the correct timing, magnitude, dependence in space and distributions were searched for. This was done using a previously developed simulation algorithm. The new fields showed that the same hydrograph could have been produced by two main types of conditions, namely, early snow cover that melted and heavy rain. The plausibility of the simulated fields was also assessed by comparing their structure in space to events in recent times.</p>

scholarly journals Investigation of heuristic search functions for nonlinear substitutions for symmetric cryptography

Radiotekhnika ◽  
2021 ◽  
pp. 53-63
Author(s):  
A.A. Kuznetsov ◽  
N.A. Poluyanenko ◽  
V.A. Katrich ◽  
S.O. Kandii ◽  
Yu.A. Zaichenko
Keyword(s):  
Heuristic Search ◽  
Input Data ◽  
Mathematical Problem ◽  
Hill Climbing ◽  
Symmetric Cryptography ◽  
Random Generation ◽  
Genetic Search ◽  
Computational Costs ◽  
The One ◽  
The Cost

Nonlinear substitutions (S-boxes) are used in most modern symmetric cryptoalgorithms. They are designed to mix input data and play a significant role in ensuring resistance against known cryptanalytic attacks (differential, linear, algebraic and other cryptanalysis methods). However, random generation of nonlinear substitutions with the desired indicators is an extremely difficult mathematical problem. This article explores the heuristic techniques for S-boxes informed search, in particular, discusses various cost functions used in most of the known algorithms (for example, local search, hill climbing, simulated annealing, genetic search, etc.). The aim of the study is to determine the specific parameters of heuristic functions, which, on the one hand, do not reduce the degree of awareness of the search nodes, and on the other hand, do not require significant computational costs. The article examines the influence of individual parameters on the value of the cost function and complexity of its calculation. It also provides specific recommendations for the formation of parameters for heuristic search for S-boxes, which significantly affect the efficiency of generating nonlinear substitutions for symmetric cryptography.

Quaternionic accelerometer/magnetometer attitude determination using symbolic computations

2018 ◽  
Vol 233 (2) ◽  
pp. 133-143
Author(s):  
Qiang Han ◽  
Xianguo Tuo ◽  
Da Lin
Keyword(s):  
Input Data ◽  
Attitude Determination ◽  
Mathematical Problem ◽  
High Accuracy ◽  
Significant Aspect ◽  
Symbolic Computations ◽  
Complex Quaternion ◽  
Normalization Problem

Attitude determination is a significant aspect of the navigation technology. The determination of the attitudes based on accelerometer and magnetometer fusion is basically an applied mathematical problem. In this article, we obtained the proposed quaternionic symbolic solution for accelerometer and magnetometer fusion which is quite different from existing methods. The proposed symbolic solution has the advantages of high accuracy and consumes much less time. Besides, the normalization problem of input data was discussed. Biquaternions ware introduced to describe the existence of the complex quaternion. Several experiments were carried out to verify the proposed symbolic solution.

Reservoir Drought Prediction Using Two-Stage SVM

2013 ◽  
Vol 284-287 ◽  
pp. 1473-1477 ◽  
Author(s):  
Jie Lun Chiang ◽  
Yu Shiue Tsai
Keyword(s):  
Prediction Accuracy ◽  
Input Data ◽  
Support Vector ◽  
Severe Drought ◽  
Two Stage ◽  
Critical Limit ◽  
Data Set ◽  
Drought Prediction ◽  
Time Period ◽  
Operation Rule

The support vector machine (SVM) has been applied to drought prediction and it typically yields good performance on overall accuracy. However, the prediction accuracy of the drought category is much lower than that of the non-drought and severe drought categories. In this study, a two-stage approach was used to improve the SVM to increase the drought prediction accuracy. Four features, (1) reservoir storage, (2) inflows, (3) critical limit of operation rule curves, and (4) the Nth ten-day in a year, were used as input data to predict reservoir drought. We used these features as input data because they are the most commonly kept records in all reservoir offices. Empirical results show that the two-stage SVM outperforms the original SVM and the three other approaches (artificial neural networks, maximum likelihood classifier, Bayes classifier) for drought prediction. Not surprisingly, the longer the prediction time period, the lower the prediction accuracy is. However, the accuracy of predicting conditions within the next 50 days was approximately 85% both in training and testing data set by the two-stage SVM. Drought prediction provides information for reservoir operation and decision making in terms of water allocation and water quality issues. The result shows the benefit of a two-stage approach of SVM for drought prediction, as the accuracy of drought prediction increased quite substantially.

The Tempo and mode(S) of Prebiotic Evolution

1997 ◽  
Vol 161 ◽  
pp. 419-429 ◽  
Author(s):  
Antonio Lazcano
Keyword(s):  
Origin Of Life ◽  
Organic Compounds ◽  
Biological Evolution ◽  
Current Evidence ◽  
Early Diversification ◽  
Time Period ◽  
The Galaxy ◽  
History Of ◽  
Widespread Phenomenon ◽  
The Origin Of Life

AbstractDifferent current ideas on the origin of life are critically examined. Comparison of the now fashionable FeS/H2S pyrite-based autotrophic theory of the origin of life with the heterotrophic viewpoint suggest that the later is still the most fertile explanation for the emergence of life. However, the theory of chemical evolution and heterotrophic origins of life requires major updating, which should include the abandonment of the idea that the appearance of life was a slow process involving billions of years. Stability of organic compounds and the genetics of bacteria suggest that the origin and early diversification of life took place in a time period of the order of 10 million years. Current evidence suggest that the abiotic synthesis of organic compounds may be a widespread phenomenon in the Galaxy and may have a deterministic nature. However, the history of the biosphere does not exhibits any obvious trend towards greater complexity or «higher» forms of life. Therefore, the role of contingency in biological evolution should not be understimated in the discussions of the possibilities of life in the Universe.

Recent Radiative and Collisional Atomic Data of Astrophysical Interest

1988 ◽  
Vol 102 ◽  
pp. 129-132
Author(s):  
K.L. Baluja ◽  
K. Butler ◽  
J. Le Bourlot ◽  
C.J. Zeippen
Keyword(s):  
Mass Production ◽  
Bound States ◽  
Physical Models ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Atomic Data ◽  
Isoelectronic Sequence ◽  
Astrophysical Interest ◽  
Radiative Transitions ◽  
Forbidden Transitions

SummaryUsing sophisticated computer programs and elaborate physical models, accurate radiative and collisional atomic data of astrophysical interest have been or are being calculated. The cases treated include radiative transitions between bound states in the 2p4and 2s2p5configurations of many ions in the oxygen isoelectronic sequence, the photoionisation of the ground state of neutral iron, the electron impact excitation of the fine-structure forbidden transitions within the 3p3ground configuration of CℓIII, Ar IV and K V, and the mass-production of radiative data for ions in the oxygen and fluorine isoelectronic sequences, as part of the international Opacity Project.

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