scholarly journals The effect of the application of the exact and approximate methods on values of selected ecological indices

2014 ◽  
Vol 67 (1) ◽  
pp. 39-46
Author(s):  
Maria Ługowska ◽  
Zofia Rzymowska
Keyword(s):  
Wiener Index ◽  
Ecological Indices ◽  
Exact Methods ◽  
Approximate Methods ◽  
Winter Cereals ◽  
Spring Cereals ◽  
Phytosociological Relevés ◽  
Exact And Approximate Methods ◽  
Potato Crops ◽  
Tuber Crops

<p>The work presents the results of a study on the biodiversity of agrocenoses using ecological indices. In order to calculate the measures, phytosociological relevés were made and exact methods were applied in winter cereals, spring cereals, tuber crops and stubble fields. The objective of the work was to compare ecological indices (Simpson’s index of dominance <em>C</em>, Simpson’s index of species richness <em>D,</em> and Shannon-Wiener index of biodiversity <em>H</em>’) calculated using the number of plants and their cover determined based on the degree of presence. Moreover, correlation analysis was conducted between the indices computed using the two approaches applied.</p><p>The results of the study revealed significant differences between all the indices calculated using the exact and approximate methods. In turn, comparisons of the measures computed for individual crops showed significant differences only for potato crops and winter cereals. No significant differences were found between the indicators calculated for spring cereals and stubble fields.</p>

scholarly journals Species diversity of segetal communities in tuber crops and in winter and spring cereals

2013 ◽  
Vol 66 (3) ◽  
pp. 95-102
Author(s):  
Zofia Rzymowska ◽  
Maria Ługowska ◽  
Janina Skrzyczyńska
Keyword(s):  
Species Diversity ◽  
Species Abundance ◽  
Wiener Index ◽  
Species Number ◽  
Individual Species ◽  
Soil Conditions ◽  
Weed Communities ◽  
Spring Cereals ◽  
Dominance Indices ◽  
Tuber Crops

The work presents the results of studies on the diversity of weed communities in tuber crops as well as in winter and spring cereals under similar climatic and soil conditions. We examined overall species abundance in the groups analysed, the average species number per relevé, as well as weed cover of the study area. Additionally, species composition, number of individual species and their biomass were determined. Dominant species in each crop group were distinguished. Species diversity was determined based on the following ecological indices: the Shannon-Wiener index of biodiversity <em>H’</em> and Simpson’s index of dominance <em>C</em>. The indices were computed on the biomass and number-of-species basis. The objective of the work was to compare the structure and diversity of weed communities in the crops studied. The communities analysed differed in all the characteristics examined. Differences were found between biodiversity and dominance indices calculated for individual crop groups, but their significance depended on the method applied to calculate the indices.

Bio-Inspired Metaheuristics

2020 ◽  
Vol 10 (4) ◽  
pp. 1-18
Author(s):  
Rachid Kaleche ◽  
Zakaria Bendaoud ◽  
Karim Bouamrane
Keyword(s):  
Real Life ◽  
Optimal Solution ◽  
Np Hard ◽  
Exact Methods ◽  
Approximate Methods ◽  
Life Problems ◽  
Comprehensive Survey ◽  
Hard Problems ◽  
Exact And Approximate Methods ◽  
Np Hard Problems

In real life, problems becoming more complicated, among them NP-Hard problems. To resolve them, two families of methods exist, exact and approximate methods. When exact methods provide the optimal solution in an unacceptable amount of time, the approximate ones provide good solutions in a reasonable amount of time. Approximate methods are two kinds, heuristics and metaheuristics. The first ones are problem specific, while metaheuristics are independent from problems. A broad number of metaheuristics are inspired from nature, specially from biology. These bio-inspired metaheuristics are easy to implement and provide interesting results. This paper aims to provide a comprehensive survey of bio-inspired metaheuristics, their classification, principals, algorithms, their application domains, and a comparison between them.

EXACT AND APPROXIMATE METHODS FOR DATA DIRECTED MICROAGGREGATION IN ONE OR MORE DIMENSIONS

2002 ◽  
Vol 10 (05) ◽  
pp. 459-476 ◽  
Author(s):  
GORDON SANDE
Keyword(s):  
Cluster Size ◽  
Linear Optimization ◽  
Economic Data ◽  
Fixed Size ◽  
Exact Methods ◽  
Approximate Methods ◽  
Minimum Cluster Size ◽  
Higher Dimensional ◽  
Size Groups ◽  
Exact And Approximate Methods

Microaggregation is a technique for the protection of the confidentiality of respondents in microdata releases. It is used for economic data where respondent identifiability is high. Microaggregation releases the averages of small groups in which no single respondent is dominant. It was developed for univariate data. The data was sorted and the averages of adjacent fixed size groups were reported. The groups can be allowed to have varying sizes so that no group will include a large gap in the sorted data. The groups become more homogeneous when their boundaries are sensitive to the distribution of the data. This is like clustering but with the number of clusters chosen to be as large as possible subject to homogeneous clusters and a minimum cluster size. Approximate methods based on comparisons are developed. Exact methods based on linear optimization are also developed. For bivariate, or higher dimensional, data the notion of adjacency is defined even though sorting is no longer well defined. The constraints for minimum cluster size are also more elaborate and not so easily solved. We may also use only a triangulation to limit the number of adjacencies to be considered in the algorithms. Hybrids of the approximate and exact methods combine the strengths of each strategy.

Comparison of exact and approximate methods for analysing vibrational relaxation regions

1961 ◽  
Vol 10 (1) ◽  
pp. 33-47 ◽  
Author(s):  
P. A. Blythe
Keyword(s):  
Exact Solution ◽  
Shock Waves ◽  
Numerical Integration ◽  
Vibrational Relaxation ◽  
Relaxation Frequency ◽  
Rayleigh Line ◽  
Relaxation Equation ◽  
Approximate Methods ◽  
Exact And Approximate Methods

The validity of various solutions for the vibrational relaxation region in shock-waves, and of the assumptions on which they are based, has been assesed by comparison with an exact solution obtained by numerical integration of the relaxation equation, and also by use of the Rayleigh-line equations. Estimates of errors in the values of the relaxation frequency, determined by means of these solutions, are given.

Optimal Feedback Solutions for a Class of Distributed Systems

1966 ◽  
Vol 88 (2) ◽  
pp. 337-342 ◽  
Author(s):  
H. C. Khatri ◽  
R. E. Goodson
Keyword(s):  
Heat Transfer ◽  
Integral Equation ◽  
Control System ◽  
Partial Differential Equations ◽  
Differential Equations ◽  
Lagrange Equations ◽  
Partial Differential ◽  
Approximate Methods ◽  
Exact And Approximate Methods ◽  
Good Agreement

In the design of controllers for heat transfer systems, one must often describe the plant dynamics by partial differential equations. The problem of optimizing a controller for a system described by partial differential equations is considered here using exact and approximate methods. Results equivalent to the Euler-Lagrange equations are derived for the minimization of an index of performance with integral equation constraints. These integral equation constraints represent the solution of the partial differential equations and the associated boundary conditions. The optimization of the control system using a product expansion as an approximation to the transcendental transfer function of the system is also considered. The results using the two methods are in good agreement. Two examples are given illustrating the application of both the exact and approximate methods. The approximate method requires less computation.

scholarly journals Exact Optimum Design of Segmented Thermoelectric Generators

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
M. Zare ◽  
H. Ramin ◽  
S. Naemi ◽  
R. Hosseini
Keyword(s):  
Maximum Efficiency ◽  
Thermoelectric Generators ◽  
Approximate Methods ◽  
Design And Optimization ◽  
Compatibility Factor ◽  
Maximum Conversion Efficiency ◽  
Design Characteristics ◽  
Exact And Approximate Methods ◽  
And Performance ◽  
Theoretical Results

A considerable difference between experimental and theoretical results has been observed in the studies of segmented thermoelectric generators (STEGs). Because of simplicity, the approximate methods are widely used for design and optimization of the STEGs. This study is focused on employment of exact method for design and optimization of STEGs and comparison of exact and approximate results. Thus, using new highly efficient thermoelectric materials, four STEGs are proposed to operate in the temperature range of 300 to 1300 kelvins. The proposed STEGs are optimally designed to achieve maximum efficiency. Design and performance characteristics of the optimized generators including maximum conversion efficiency and length of elements are calculated through both exact and approximate methods. The comparison indicates that the approximate method can cause a difference up to 20% in calculation of some design characteristics despite its appropriate results in efficiency calculation. The results also show that the maximum theoretical efficiency of 23.08% is achievable using the new proposed STEGs. Compatibility factor of the selected materials for the proposed STEGs is also calculated using both exact and approximate methods. The comparison indicates a negligible difference in calculation of compatibility factor, despite the considerable difference in calculation of reduced efficiency (temperature independence efficiency).

scholarly journals Accumulation of biomass and bioenergy in culms of cereals as a factor of straw cutting height

2017 ◽  
Vol 31 (2) ◽  
pp. 273-285
Author(s):  
Tomasz Zając ◽  
Agnieszka Synowiec ◽  
Andrzej Oleksy ◽  
Jan Macuda ◽  
Agnieszka Klimek-Kopyra ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Spring Barley ◽  
Winter Barley ◽  
Biomass Energy ◽  
Winter Cereals ◽  
Cereal Species ◽  
Arable Fields ◽  
Spring Cereals ◽  
Biometric Measurements ◽  
Cutting Height

Abstract Cereal straw is an important biomass source in Europe. This work assessed: 1) the morphological and energetic characteristics of culms of spring and winter cereals, 2) the energy deposited in the different aboveground parts of cereals, 3) losses of energy due to different cutting heights. The straw of winter and spring cereals was collected from arable fields during the seasons 2009/10 and 2010/11 in southern Poland. Detailed biometric measurements of culms and internodes were performed. The losses of straw biomass and energy were assessed during simulation of cutting the culm at different heights, up to 50 cm. Longer and heavier culms were developed by winter wheat and triticale and oat. Cutting of straw up to 10 cm did not lead to significant losses in straw yield. The total amount of energy in the culms was as follows: triticale > winter wheat > oat > spring wheat > winter barley > spring barley. Cutting the culms above 20 cm led to significant differences in terms of biomass energy between cereal species. The smallest losses of energy were recorded for spring and winter barley. Oat and barley accumulated the highest energy in grains.

Computation of atmospheric cooling rates by exact and approximate methods

1991 ◽  
Vol 96 (D5) ◽  
pp. 8969 ◽  
Author(s):  
William L. Ridgway ◽  
Harshvardhan ◽  
Albert Arking
Keyword(s):  
Approximate Methods ◽  
Cooling Rates ◽  
Exact And Approximate Methods
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