Persistent Scatterer Interferometry (PSI), a remote sensing technique, is used for detecting surface deformation in the cities of Prague and Ostrava. PSI is able to detect vertical movements with an accuracy of less than 1 mm for a long time series of the SAR data, but the maximum detectable rate of movement is only a few centimetres per year. This technique is quite suitable for detecting recent movements in most Prague localities. On the other hand, in Ostrava and its surroundings, affected by undermining, where subsidences (1992-2006) amount to decimetres per year, movements cannot be fully detected by the PSInSAR technique. The paper presents results of analysing PSI data for two localities in Prague and one locality in the Ostrava areas. The localities are strictly situated in built-up areas with many suitable reflectors. Data from the ERS-1/2 and ENVISAT satellites covering a 13-year period for the Prague (1992-2005) and a 14-year period for the Ostrava (1992-2006) area were used. Annual movement velocities and time-series of reflectors were determined. At these three localities, where different types of movements were identified, the application and possible limitations of PSI in urban areas are shown., Pavel Kadlečík, Vladimír Schenk, Zuzana Seidlová and Zdeňka Schenková., and Obsahuje bibliografii
The main objective of this paper is to explain how the application of various interpolation methods influence the determination of vertical crustal movements at any given point. The paper compares several methods of interpolation and verifies their suitability, including kriging, minimum curvature, nearest neighbor, natural neighbor, polynomial regression, inverse distance to a power, and triangulation with linear interpolation. The calculations show that the chosen interpolation method has significant influence on the final result of the study. Nearest neighbor method was chosen to be the best., Kamil Kowalczyk, Jacek Rapinski and Marek Mroz., and Obsahuje bibliografii
Einstein-Barbarossa velocity or resistance equation (1952) is widely used to find resistance to flow in alluvial channel. In order to validate the equation in all ranges (smooth to rough); they introduced a correction factor based on the Nikuradse measurement. This correction factor is determined from the graphical method, which can be erroneous. Present work reanalyzes the Nikuradse measurements and gives an analytical formulation for the correction factor. and Einsteinova-Barbarossova rovnica (1952) sa často používa na určenie odporu voči prúdeniu v kanáloch. Autori do nej zaviedli korekčný faktor, založený na meraniach Nikuradzeho, aby overili platnosť rovnice v celom rozsahu drsností (od hladkých stien po drsné). Tento korekčný faktor sa určuje grafickou metódou, ktorá môže viesť k chybným výsledkom. V tejto práci sa znova analyzujú výsledky Nikuradzeho meraní a je navrhnutá analytická formulácia na výpočet korekčného faktora.
An improved theoretical formulation is proposed here to predict the moment field induced in laterally loaded RC rectangular stiffened plates including the effect of strength and stiffness of the internal stiffening beams. Design charts are also presented for their quick proportioning. The study reveals the effect of strength and stiffness of the internal beams on the moment field induced in the plate-system which was not considered, currently, by various methods prescribed by different design codes. The use of stiffened-plates becomes mandatory in buildings to accomodate some architectural constraints as well as for satisfying the serviceability criterion of design codes. This type of a structural system is efficient, economical and readily constructible in most of common materials. Moreover, it can be built as a monolithic unit or as a composite system comprising a plate cast in concrete and beams constructed in prestressed concrete, fabricated sections in steel, and so forth. A working example is presented to demonstrate the validity and efficiency of the simplified approach in comparison to finite element based design and other code prescribed methods. and Obsahuje seznam literatury a Appendix A
This paper presents closed form solution for unsteady flow equation corresponding to the transient hydraulic head, flow rate and volumetric exchange of a confined aquifer which is in contact with a constant piezometric head at one end and a stream whose water level is rising at a constant rate at the other end. The aquifer is also subjected to receive constant inflow due to rain infiltration. The unsteady groundwater flow equation is solved using Laplace transform to get analytical expressions for the transient hydraulic head and flow rate at the left and right interfaces and the net volumetric exchange of water at the aquifer-stream interface. The analytical results presented here show the effect of recharge due to rain infiltration on the net volumetric exchange and reveal the conditions for which net inflow in the aquifer could be positive, negative or zero. The results obtained have the capability to determine transient hydraulic head for two extreme scenarios: (i) very slow rise and (ii) very fast rise in the stream water. Analytical result show that the net volumetric exchange could be positive, zero or negative depending on the surface infiltration and stream water rise rate. and Príspevok obsahuje analytické riešenie rovnice neustáleného prúdenia vzhľadom na neustálenú hydraulickú výšku, rýchlosť prúdenia a objemové toky vo zvodnenom kolektore s napätou hladinou, ktorý je v kontakte s konštantnou piezometrickou výškou na jednej strane a s tokom s konštantne sa zvyšujúcou hladinou vody na strane druhej. Zvodnený kolektor je tiež napájaný konštantnou rýchlosťou infiltrovanou vodou zo zrážok. Rovnica neustáleného prúdenia podzemnej vody je riešená s použitím Laplaceovej transformácie, aby sme získali neustálenú tlakovú výšku na ľavej aj pravej strane a objemový prítok vody na rozhraní zvodnený kolektor - tok. Výsledky analytického riešenia, ktoré predkladáme, ukazujú vplyv infiltrácie zrážok na doplňovanie podzemnej vody a odhaľujú podmienky, za ktorých prítok do zvodneného kolektora môže byť kladný, negatívny, alebo nulový. Získané výsledky umožňujú určiť neustálené hydraulické výšky pre dva extrémne scenáre: (i) veľmi pomalé a (ii) veľmi rýchle zvýšenie hladiny vody v toku. Analytické riešenie ukazuje, že objem vody, ktorou je zvodnený kolektor doplňovaný, môže byť kladný, záporný, alebo nulový, v závislosti na intenzite infiltrácie a rýchlosti zvyšovania sa hladiny vody v toku.
The paper deals with a new manner of obtaining a closed-form analytical solution of the problem of bending of a beam on an elastic foundation. The basic equations are obtained by a variational formulation based on the minimum of the total potential energy functional. The basic methods for solving the governing equations are considered and their advantages and disadvantages are analyzed. The author proposes a felicitous approach for solving the equilibrium equation and applying the boundary conditions by transformation of the loading using singularity functions. This approach, combined with the resources of the modern computational algebra systems, allows a reliable and effective analysis of beams on an elastic foundation. The numerical examples show the applicability and efficiency of the approach for the solution of classical problems of soil-structure interaction. and Obsahuje seznam literatury
An analytical solution for the two-dimensional tension leg platform (TLP) interacting with ocean wave is presented. The legs of TLP are considered as elastic springs. The flow is assumed to be irrotational and single-valued velocity potentials are defined. The effects of radiation and scattering are considered in the boundary value problem. Because of linear behavior of legs during wave excitation, ignoring coupling effects with other degrees of freedom, the analytical solution of heave response has good agreement with the real behavior of the structure. and Práce uvádí analytické řešení působení vln na dvoudimenzionální pevně ukotvenou plošinu (TLP). Úchyty plošiny jsou uvažovány jako elastické pružiny. Předpokládá se nevírový tok a je definováno jednoznačné rychlostní pole. Okrajové podmínky zahrnují vlivy radiace a rozptylu. Předpoklad lineárního chování úchytů při excitaci mořskými vlnami i zanedbání některých dalších efektů v analytickém řešení odezvy TLP na vznášení ukázaly, že existuje soulad mezi naším řešením a skutečným chováním konstrukce.
The article presents an analytical solution to deterministic problems of infinite fatigue life (determining the safety factor, predicting tha carrying capacity and proposing the cross-section dimensions) of machine parts subjected to arbitrary pure harmonic loading. Presented mathematical models do not require to construct any fatigue strength diagram adopting it only as a basis of graphical solving. Finally, these models may serve as a starring point formulating analytical solution to deterministic problems of infinite fatigue life of machine parts under combined harmonic loading. and Obsahuje seznam literatury
A new analytical formula of the velocity profile for both the laminar and turbulent flow in a tube with a circular cross-section will be introduced in his article. This formula is rather simple and easy to use. The advantage of this velocity profile is that one formula can be used for laminar and turbulent flow. This new formula will be compared with power law velocity profile and with the law of the wall also called as the log-law. and Obsahuje seznam názvosloví