Wyniki wyszukiwania - Biblioteka Nauki

1

Nonparametric instrumental variables for identification of block-oriented systems

100%

Mzyk G.

|

tom 23

|

nr 3

521-537

EN

A combined, parametric-nonparametric identification algorithm for a special case of NARMAX systems is proposed. The parameters of individual blocks are aggregated in one matrix (including mixed products of parameters). The matrix is estimated by an instrumental variables technique with the instruments generated by a nonparametric kernel method. Finally, the result is decomposed to obtain parameters of the system elements. The consistency of the proposed estimate is proved and the rate of convergence is analyzed. Also, the form of optimal instrumental variables is established and the method of their approximate generation is proposed. The idea of nonparametric generation of instrumental variables guarantees that the I.V. estimate is well defined, improves the behaviour of the least-squares method and allows reducing the estimation error. The method is simple in implementation and robust to the correlated noise.

2

Nonparametric methods in the analysis of the quality of kernel of selected winter wheat cultivars

100%

Ćwiklińska M. , Hanusz Z. , Soja J. , Polak R.

Agricultural Engineering

|

2021

|

tom Vol. 25, No. 1

125--134

EN

The paper presents a statistical analysis of weight and diameter of kernel obtained for eight investigated winter wheat cultivars. Preliminary analyses of experimental results, such as compliance with a normal distribution, equality of variance for particular cultivars, and occurrence of outliers proved that there is no justification for the use of a traditional one-way analysis of variance for verification of hypotheses according to which weight and diameter of grains of the investigated winter wheat cultivars do not differ. A nonparametric Kruskal-Wallis test was used for verification of hypotheses which based on the experimental results enabled to reject both hypotheses. Further, simultaneous average weight and diameters of grain of the investigated cultivars were compared with the use of Nemenyi-Dunn test. The applied test enabled to conclude which cultivars had a significantly higher weight than the others. Analogous comparisons were carried out for the diameter of kernels of the investigated winter wheat cultivars.

PL

W pracy przedstawiono analizę statystyczną masy oraz średnicy ziarniaków uzyskanych dla ośmiu badanych odmian pszenicy ozimej. Wstępne analizy wyników eksperymentalnych, takie jak, zgodność z rozkładem normalnym, równość wariancji dla poszczególnych odmian oraz wystąpienie obserwacji odstających, wykazały brak podstaw do zastosowania klasycznej jednokierunkowej analizy wariancji do weryfikacji hipotez o braku zróżnicowania masy oraz średnicy ziarniaków badanych odmian pszenicy ozimej. Do weryfikacji hipotez wykorzystano nieparametryczny test Kruskala-Wallisa, który w oparciu o wyniki eksperymentalne pozwolił odrzucić obydwie hipotezy. W dalszej kolejności dokonano porównań jednoczesnych średnich mas i średnic ziarniaków badanych odmian stosując test Nemenyi-Dunna. Zastosowany test pozwolił stwierdzić, które odmiany charakteryzowały się masą istotnie wyższą od pozostałych. Analogiczne porównania przeprowadzono dla średnicy ziarniaków badanych odmian pszenicy ozimej.

3

A parallel net of (1-NN, K-NN) classifiers for optical inspection of surface defects in ferrites

100%

Jóźwik A. , Chmielewski L. , Skłodowski M. , Cudny W.

Machine Graphics and Vision

|

1998

|

tom Vol. 7, No. 1/2

99-112

EN

The challenging task of optical inspection of surface defects in ferrite cores has been successfully approached with a set of methods. In this paper the attention is paid to the k Nearest Neighbours classifier developed for the system. A parallel net of two-decision classifiers is presented. The combination of the 1-NN and k-NN rules reduces the training time. A great part of computations is restricted to the class overlap area. The classification quality is significantly improved if a separate feature selection for each of the component classifiers is done. A dramatic improvement of classification speed obtained by reference patterns sets reduction for component classifiers is vital, as in the considered task the classifier is used for recognition of pixels. The proposed modifications of the classifier are of general usefulness for pattern recognition. The presented quality inspection system can be applied to various defect detection tasks.

4

Analysis of the spatial variability of the concentrations of Na+ and K+ ions in the groundwater sourced in Southern Poland

84%

Kotowski T. , Satora S.

Environment Protection Engineering

|

2016

|

tom Vol. 42, nr 2

5--18

EN

Differences in the spatial variability of Na+ and K+ ion concentrations in the groundwater sourced in Southern Poland have been analysed. The study was based on selected hydrogeological environments differing in the lithology and geometry of aquifer rock voids. The hydrogeochemical background for Na+ and K+ ions was determined for various hydrogeological environments as well. The hydroge-ochemical background ranges obtained do not deviate significantly from the background ranges for groundwater observed in other areas of Poland. The analyses conducted indicate the presence of anomalous concentrations of Na+ and K+ ions in all hydrogeological environments often accompanied with significantly elevated concentrations of Cl- and SO42– ions. Owing to the fact that the data analysed exhibit a distribution deviating considerably from a normal one, non-parametric methods of statistical inference were used. The results obtained indicate statistically significant differences between the variabilities of Na+ and K+ ion concentrations in various hydrogeological environments. The factors responsible for such differences are lithological variability and different groundwater circulation systems.

5

The Level of Hard Competencies and the Amount of Earnings – Evaluation by Selected Nonparametric Methods

67%

Grześkowiak A.

|

tom 5

|

nr 338

143-156

PL

W artykule podjęto tematykę porównania zarobków osiąganych w grupach osób deklarujących różny poziom posiadanych kompetencji twardych: umiejętności analizowania informacji, kompetencji informatycznych, obsługi urządzeń, wykonywania obliczeń oraz znajomości języka obcego. Analizę przeprowadzono na podstawie danych z ogólnopolskiego badania Bilans Kapitału Ludzkiego. Do oceny różnic w zarobkach zastosowano nieparametryczne metody statystyczne: estymację jądrową oraz koncepcję rozkładów względnych. Wyniki badania wskazują, że lepszym umiejętnościom towarzyszą wyższe zarobki oraz że różnice wykazują odmienności w zależności od typu kompetencji.

EN

The article discusses the comparison of earnings achieved in groups of people who declare different levels of following hard competences: information analysis abilities, computer skills, machine operation, making calculations and foreign language skills. The analysis is based on data from the nationwide study of the Human Capital in Poland. Nonparametric statistical methods are used to evaluate the differences in earnings: the kernel estimation and the concept of relative distributions. The results show that better skills are associated with higher earnings and that there are differences depending on the type of competencies.