National Repository of Grey Literature 52 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Possibilities of using 4D computed tomography in fracture tests
Kumpová, Ivana ; Fíla, Tomáš ; Koudelka, Petr ; Rozsypalová, I. ; Keršner, Z. ; Kytýř, Daniel ; Vopálenský, Michal ; Vavřík, Daniel ; Vyhlídal, M. ; Drdácký, Miloš
The paper presents the study of the internal structure and fracture properties of selected quasi-brittle building materials subjected to temperature changes and the possibility of applying the method combining bending fracture tests and time-dependent computed tomography (4D CT). The tested specimens were subjected to hightemperature effects and subsequently tested by a four-point bending during 4D CT. Thus, 3D image information was obtained in different phases of loading and material damage. Comparative compression strength measurements were also performed. These results are in good agreement
Experiment E7/0,3-displacement processes in non cohesive sand mass during active translative motion of retaining wall
Koudelka, Petr
The first part of information on the new experiment denominated as E7/0,3 with active pressure of non-cohesive quartz sand on time behaviour of the mass was presented at the last Conference (P. Koudelka, 2015). The second part is object of this Paper. The experiment was performed at the Institute of Theoretical and Applied Mechanics in 2014. The moved rigid front wall of the experimental equipment was translatively moved towards active direction (out of the mass) at a position of supposed acting of active pressure value, then the wall motion was stopped and time pressure stability was monitored. After more than three months the wall was moved at the last position of 100 mm from original position before the experiment. The experiment ran four and a half months. The paper presents firstly results on the deforming mass through the course of the wall movement at a supposed position for active pressure mobilization of 1.357 mm and after the further movement. The experiment was repeated to be the results proved (Experiment E8/0,3). New results are analysed.
A Language for Programming the Adventure Games
Koudelka, Petr ; Smrčka, Aleš (referee) ; Hrubý, Martin (advisor)
This thesis deals with design and realization of programming language for adventure games programming. This language was supposed to been suitable for users without knowledge of programming. Reader is introduced to problematic of adventure games and there history. Then a reader is informed that the created language is interpreted imperative programming language, with elements of structured and unstructured languages. The name of designed language is AGScript. Interpret was also created as a part of this thesis. Next phase was creation of demonstration application with use of AGScript. This application was inspired by a book called The Warlock of The Firetop Mountain. With this, usability of AGScript was verified. Last phase of the thesis consists of two experiments. The aim of first experiment was confirmation of comprehensibility of AGScript. The result was positive. The second experiment was inquiring demonstration application. Keywords
On geotechnical design according to residual shear strength
Koudelka, Petr
The paper consider on possibility and effectivity of a new concept of ULS design on residual shear strength based. Values of residual shear strength are the most reliable and in opposite, applied peak values of shear strength are the most favorable and applicable for states of small deformations only. The paper presents results of a prior analysis of slope stability and compares designs applying values of residual shear strength and peak shear strength. Some recommendations are included.
DEA analysis applied to Tax Offices in Czech Republic
Koudelka, Petr ; Jablonský, Josef (advisor) ; Fiala, Petr (referee)
Data envelopment analysis models are common tools to measure efficiency of decision-making unit. This thesis presents several DEA-based approaches and describes data that are collected and closely watched by Czech Tax Offices. Presented methods are used to evaluate Tax Offices. Each Tax Office will be evaluated with efficiency rate by every presented approach. In the last part of this thesis, the Tax Offices will be ordered by achieved results and the methods will be compared.
Shear strength of sand under very low normal load
Hudek, J. ; Koudelka, Petr
Solutions of some extraordinary geotechnical problems need knowledge of shear strength in a scale of very low normal stress. An example is physical modelling of soil mass behaviour using medium or little samples. The paper deals with results of testing a very dry uniform quartz sand of medium size. Resulting values of effective shear strength for the normal stress scale till of 25 kPa are compared with former testing of the same material in other scale of 63 – 163 kPa.
Application of soil designes values according to ULSD of EC 7-1 in Czech conditions
Koudelka, Petr
Some contemporary European codes (e.g., EC 1, EC 7-1) and standards (e.g., ČSN 73 0031) have taken into account in their theoretical bases a special granular character of soils and rocks with a different extent. The EUROCODES, i.e. EUROCODE 1 (EN 1991-1) "Basis of design and actions on structures - Part 1: Basis of design" and EUROCODE 7-1 (EN 1997-1) "Geotechnical design - Part 1: General rules" consider underground environment/mass in the same way as the other structures (e.g. steel, concrete, masonry, timber) without any theoretical exception for analyses of three-phase granular material structures. Thus, using theory of the Ultimate Limit State Design (ULSD), a statistical definition of characteristic values and several partial factors have been considered along with material partial factors for material design values of the soil mass properties.
Experiment E5/0,1 with lateral passive pressure during rotation about the toe - granular mass deformations
Koudelka, Petr ; Bryscejn, Jan
A basic physical experimental research of lateral passive pressure is in progress at the Institute. The research is composed of three doubles of the same experiments with three basic retaining wall movements: rotations about the toe and top and translative motion. The experiment E5/0,1 with passive pressure and pressure at rest during wall rotation about the toe was carried out in 1st half 2012 and it was the first of the same experiment double (the 2nd one was the experiment E6/0,1 finished in the early 2013. Both experiments together should prove a real behaviour of non-cohesive mass acting on moving wall. The behaviour appears distinct from a theory of EUROCODE 7-1 contemporaneously used. Each of experiments has brought a huge data quantity. The paper shows mass deformations and slip surfaces of the experimental sandy mass.
Development of Retaining Structures of the Prague Metro
Koudelka, Petr
The Paper shows a state of theoretical and practical knowledge in design of retaining structures at beginning 60ties when a project of underground system started (the 1st section of line C- IC) and after. The project brought great stride and development in Czech geotechnics which had to solve tasks not solved before (e.g. big excavated pits of depths more than 8 m in built-up area, applications of new technologies). The paper concentrates on a designer practice and a development of the earth pressure theory.
Speedy partial process of lateral pressure in granular mass during consolidation – Experiment E5/0,2
Koudelka, Petr ; Bryscejn, Jan
The long-term experiment E5/0,2 with pressure at rest and passive pressure of ideally non-cohesive sand ran in 2010 and consist of a number of phases which brought huge quantity of data. The experiment contained also a phase of consolidation after passive wall rotation about the top with a toe movement of 15.6 mm. Movement velocity of the front wall toe was 0.005 mm/min. only. On the contrary, processes of the pressure components (normal and shear) were surprisingly quick. The Paper presents an analysis of a process of time pressure instability at the beginning and the end of a reconsolidation phase.

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