46 research outputs found
Xylogenesis and phloemogenesis of Norway spruce in different ages stands at middle altitudinal zone
This study aimed to determine the influence of the stand age and selected weather conditions on the cambial activity, xylem and phloem formation and their development. For the analysis, microcores were taken weekly from two corresponding stands of Norway spruce (Picea abies (L.) Karst.) with various ages (35- and 106-years-old) during the growing season 2012 in the Czech Republic. Young specimens were characterised by higher cambium activity; however, more considerable variation and imbalance were found there. In old trees, delayed processes during the development of the xylem and phloem at the cell level were proved. The cambium activity started in March till mid-April, and it lasted for 22 weeks in both cases. The commencement of xylogenesis was established in the first half of May. In both investigated stands, the fully lignified ring was observed at the end of October. For the creation of most xylem cells, it was required 124 and 121 days in the young and old stands, respectively. Daily increment of 0.57 (young) and 0.49 (old) cells on average was observed during the active xylem growth. The relationship between air temperature and wood cell formation for both age groups was recorded. The precipitation influenced wood development just in the case of the young trees. Phloem formation was resistant to external influence according to the Pearson correlation coefficient.O
Viabilidade econômica e rotação florestal de plantios de candeia (Eremanthus erythropappus), em condições de risco
PVTxy properties of CO2 mixtures relevant for CO2 capture, transport and storage: Review of available experimental data and theoretical models
Risk analysis in investment appraisal based on the Monte Carlo simulation technique
This work has been prepared for the purpose of presenting the methodology and uses
of the Monte Carlo simulation technique as applied in the evaluation of investment projects to
analyze and assess risk. In the deterministic appraisal the basic decision rule for a project is
simply to accept or reject the project depending on whether its net present value (NPV) is
positive or negative, respectively. Similarly, when choosing among alternative (mutually
exclusive) projects, the decision rule is to select the one with the highest NPV, provided that it
is positive. Recognizing the fact that the key project variables (as: volume of sales, sales
price, costs) are not certain, an appraisal report is usually supplemented to include sensitivity
and scenario analysis tests. Both tests are static and rather arbitrary in their nature.
During the simulation process, random scenarios are built up using input values for
the project's key uncertain variables, which are selected from appropriate probability
distributions. The results are collected and analyzed statistically so as to arrive at a probability distribution of the potential outcomes of the project and to estimate various measures of
project risk
Information system extension and integration with social networks
katedra softwarového inženýrstv
Cooperation between elementary schools and Police of Czech Republic in Police headquarters of Prague III
Katedra pedagogikyPedagogická fakultaFaculty of Educatio
Monitoring tvorby dřeva smrku ztepilého (Picea abies (L.) Karst.) vystaveného stresu suchem
Bayesowska estymacja punktu zmiany w modelu regresji dwufazowej
The purpose of this paper is to carry out the Bayesian analysis of
a two-phase regression model with an unknown break point. Essentially, there are two
problems associated with a changing linear model. Firstly, one will want to be able to
detect a break point, and secondly, assuming that a change has occurred, to be able
to estimate it as well as other parameters of the model. Much of the classical testing
procedure for the parameter constancy (as the Chow test, CUSUM, CUSUMSQ, tests
and their modifications, predictions tests for structural stability) indicate only that the
regression coefficients shifted, without specifying a break point.
In this study we adopt the Bayesian methodology of investigating structural changes
in regression models. The break point is identified as the largest posterior mass density,
the peak of the posterior discrete distribution of a break point. It seems to work well
with artificially generated data.
The Bayesian framework also seems to be promising for extending the analysis of
a single break to that of multiple breaks.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej naukę
Skośny rozkład normalny - podstawowe własności i obszary zastosowań
The skew-normal is a class of distribution that includes the normal distribution
as a special case. A systematic treatment of the skew-normal distribution has been given in
Azzalini (1985, 1986); generalizations to the multivariate case are given in Azzalini and Capitanio
(1999), while Azzalini and Capitanio (2003) propose a further extension with a skew-t
distribution. In this paper we study the properties of this class of density functions and we
investigate the applicability of this distributions for modeling some financial and income data.Klasa skośnych rozkładów normalnych zawiera jako szczególny przypadek rozkład normalny.
Szczegółowemu omówieniu własności rozkładu skośnego normalnego poświęcona jest
praca Azzalini (1985, 1986); przypadek wielowymiarowy przedstawili Azzalini i Capitanio (1999),
natomiast w pracy tych autorów z roku 2003 można znaleźć dalsze rozszerzenie tej klasy
rozkładów o rozkłady skośne t-Studenta. W niniejszym artykule przedstawiono podstawowe
własności funkcji gęstości omawianych rozkładów i pokazano możliwości ich wykorzystania
w modelowaniu dochodów i danych finansowych