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Start Over Creator Čermák, Jan

1. Asymptotic behaviour of solutions of some linear delay differential equations.

Creator:
Čermák, Jan
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
asymptotic behaviour, differential equation, delayed argument, and functional equation
Language:
English
Description:
In this paper we investigate the asymptotic properties of all solutions of the delay differential equation y'(x)=a(x)y(\tau(x))+b(x)y(x),\qquad x\in I=[x_0,\infty). We set up conditions under which every solution of this equation can be represented in terms of a solution of the differential equation z'(x)=b(x)z(x),\qquad x\in I and a solution of the functional equation |a(x)|\varphi(\tau(x))=|b(x)|\varphi(x),\qquad x\in I.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

2. Asymptotic properties of differential equations with advanced argument

Creator:
Čermák, Jan
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
functional differential equation, functional (nondifferential) equation, advanced argument, and asymptotic behaviour
Language:
English
Description:
The paper discusses the asymptotic properties of solutions of the scalar functional differential equation \[ y^{\prime }(x)=ay(\tau (x))+by(x),\qquad x\in [x_0,\infty ) \] of the advanced type. We show that, given a specific asymptotic behaviour, there is a (unique) solution $y(x)$ which behaves in this way.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

3. Comparative study of long-term water uptake of Norway spruce and Douglas-fir in Moravian upland

Creator:
Nadezhdina, Nadezhda, Urban, Josef, Čermák, Jan, Nadezhdin, Valeriy, and Kantor, Petr
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
sap flow, shallow roots, deep roots, heat field deformation, and soil water potential
Language:
Slovak
Description:
Long-term water uptake of Douglas-fir and Norway spruce trees, growing in condition of Moravian upland, was studied with aim of comparing sap flow in small roots with flow in stems. Sap flow was measured by the heat field deformation method using multi-point sensors for stems and single-point sensors for roots. Differences between species were found in relationships between sap flow in tree stems and water uptake by roots, suggesting that Douglas-fir is able to take water from deeper soil more efficiently than spruce. This allows Douglas-fir to transpire more water especially during drought and grow faster than spruce. These biological features should be taken into account for future forest species compositions because they may have impact on both, forestry and hydrology.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

6. K hodnocení stavu báze stromů a kořenového systému - posuzování hnilob a poškození

Creator:
Simon, Jaroslav, Buček, Antonín, and Čermák, Jan
Type:
article and TEXT
Language:
Czech
Description:
Posuzování hnilob a defektů báze kmene a hodnocení distribuce kořenového systému stromů: zjištění a posouzení hnilob a dutin na bázi kmene, zejména u starých stromů a dále hodnocení rozmístění a stavu kořenového systému jsou zásadní aspekty, které umožňují předvídat riziko destrukce stromu (vyvrácení, rozlomení). and This article deals with the methods of assessment of root and trunk base damage, as well as evaluation of distribution of root system of trees in soil. The detection and evaluation of rots and cavities in the trunk base (especially in the case of old trees) and the evaluation of the distribution and quality of root systems are the most important methods for prediction of the risk of tree destruction (uprooting and breaking of the stem).
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/

7. Note on a discretization of a linear fractional differential equation

Creator:
Čermák, Jan and Kisela, Tomáš
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
fractional difference, fractional sum, and discrete Mittag-Leffler function
Language:
English
Description:
The paper discusses basics of calculus of backward fractional differences and sums. We state their definitions, basic properties and consider a special two-term linear fractional difference equation. We construct a family of functions to obtain its solution.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

8. Sap flow index as an indicator of water storage use

Creator:
Nadezhdina, Nadezhda, Čermák, Jan, Downey, Alec, Nadezhdin, Valeriy, Perämäki, Martti, David, Jorge Soares, Pinto, Clara A., and David, Teresa Soares
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
diameter fluctuation, heat field deformation, multi-point sensor, symmetrical temperature difference, radial and circumferential variations, sap flow measurement, tree, and transpiration
Language:
Slovak
Description:
Symmetrical temperature difference also known as the sap flow index (SFI) forms the basis of the Heat Field Deformation sap flow measurement and is simultaneously collected whilst measuring the sap flow. SFI can also be measured by any sap flow method applying internal continuous heating through the additional installation of an axial differential thermocouple equidistantly around a heater. In earlier research on apple trees SFI was found to be an informative parameter for tree physiological studies, namely for assessing the contribution of stem water storage to daily transpiration. The studies presented in this work are based on the comparative monitoring of SFI and diameter in stems of different species (Pseudotsuga menziesii, Picea omorika, Pinus sylvestris) and tree sizes. The ability of SFI to follow the patterns of daily stem water storage use was empirically confirmed by our data. Additionally, as the HFD multipointsensors can measure sap flow at several stem sapwood depths, their use allowed to analyze the use of stored water in different xylem layers through SFI records. Radial and circumferential monitoring of SFI on large cork oak trees provided insight into the relative magnitude and timing of the contribution of water stored in different sapwood layers or stem sectors to transpiration.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public