National Repository of Grey Literature 34 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Analysis of fatigue damage accumulation of test specimens made from S690 and S960
Al Khazali, Mohammad ; Malíková, Lucie (referee) ; Seitl, Stanislav (advisor)
This thesis study and examines the behavior of high strength steels (HSS) during fatigue utilizing S-N curves of models based on the Palmgren-Miner Rule and some invented hypotheses, such as Haibach's model, Corten-Dolan's model and Serensen-Kogajev model. Firstly, a detailed mechanical testing will be done and discussed to ensure creating a proper understanding of the two types of steel that will be the focal point of the research. The curves created are interpolated using measured data form cyclically loaded of the steel to create the relation between the number of cycles the material can withstand before reaching failure state and the level of stress applied on a variety of specimens with different homogenizes but similar characteristics. The accuracy of each model is determined for each grade of steel, the S690 and the S960. Then we will conclude by the end of the work which can be considered suitable and which not of each model and an explanation of the reasoning behind the results achieved to ensure better outcome in future related work.
Analysis of crack behaviour under mixed-mode loading
Antalík, Adam ; Miarka, Petr (referee) ; Malíková, Lucie (advisor)
This bachelor’s thesis deals with the analysis of the stress field in the vicinity of the crack tip, described by the stress intensity factor K. The objective of this thesis is to calculate values of the parameter K for a crack in a rectangular specimen subjected to asymmetric four-point bending. Thus, mixed mode I + II loading conditions occur. The first part of the thesis deals with the fracture mechanics concept. In the second part, a cracked specimen is modelled in the Ansys Mechanical APDL software. In the final part, the resulting values of the parameter K, obtained from the commands KCALC, CINT and two empirical equations, are presented. The MTS criterion is applied for estimation of the crack propagation angel and all results are discussed thoroughly.
Habitat colonization by neophyte Impatiens glandulifera and estimate of factors limiting its spread
Marková, Zuzana ; Hejda, Martin (advisor) ; Malíková, Lenka (referee)
Invasive spread of neophyte Impatiens glandulifera in central Europe started approximatelly eighty years ago. First records of dense cover stands come from belt stands in riparian habitats. The scale of invaded habitats and degree of the dominance of I. glandulifera is more diversified nowadays. This thesis is objected on the dominance and fertility of I. glandulifera within different habitat types and scale of invaded habitats in different parts of invaded range within Europe (i. e. in Czech Republic and Switzerland). The results show that the height and cover (substitutes for biomass and dominance) of this neophyte (i) correlates with the character of invaded vegetation (ii) relates to the degree of hemeroby (a measure of human impact) negativelly, and (iii), of course, both the growth and dominance are positively affected by nutrient content. Fertility does not differ among the types of invaded habitats, but goes up with the height of I. glandulifera and decreases with its cover. Invaded habitats comprises ruderal and riparian vegetation, but also wet maedows, forest clearances, beach and slope forests or weed vegetation.
Teachers as actors of education policy: A conceptualization of actors in public policy and an application of selected approaches on the example of teachers
Mouralová, Magdalena ; Veselý, Arnošt (advisor) ; Malíková, Ludmila (referee) ; Winkler, Jiří (referee)
The doctoral thesis has primarily a theoretical character and outcomes. The focus of interest is formed by a detailed investigation of the actor concept in key theoretical approaches to contemporary public policy; the results are subsequently applied on the example of education policy, particularly on teachers as a specific actor category. The goals of this thesis are: 1) to describe how the words "actor", "agent" and "stakeholder" (which all translate as "aktér" in the Czech language) are used in public policy articles; 2) to introduce and compare selected public policy approaches working with actors; 3) to model how these approaches are used in the case of teachers (as actors) and the policy of tracking; 4) to create a comprehensive conceptual framework for the public policy research on actors. The analytical part of the doctoral thesis is based on a summative content analysis of public policy texts published in four extensive handbooks of public policy.
Perspectives on illicit drug use in the Czech Republic
Nekola, Martin ; Potůček, Martin (advisor) ; Malíková, Ludmila (referee) ; Radimecký, Josef (referee)
UNIVERZITA KARLOVA V PRAZE FAKULTA SOCIÁLNÍCH VĚD Institut sociologických studií Užívání nelegálních drog z pohledu aktérů české drogové politiky Perspectives on Illicit Drug Use in the Czech Republic Abstrakt / Abstract Studijní program: Sociologie Studijní obor: Veřejná a sociální politika Autor: Mgr. Martin Nekola Školitel: Prof. PhDr. Martin Potůček, CSc., MSc. Abstrakt Disertační práce prezentuje výsledky empirického šetření provedeného v roce 2009, jehož cílem byla identifikace stanovisek a perspektiv aktérů české drogové politiky týkajících se užívání nelegálních drog a souvisejících problémů. Práce vychází z teorie koalic aktérů, která je aplikována na drogovou politiku v České republice. Ta je spolu se stručnou analýzou rozsahu a závažnosti problému zasazena do kontextu vývoje drogových politik ve světě a EU a jsou popsány její prvky a aktéři. Empirické šetření aktérů bylo provedeno pomocí metody Q, která ve vzorku 24 účastníků identifikovala celkem tři nezávislé faktory reprezentující tři odlišné perspektivy. Mezi účastníky dominuje perspektiva kladoucí důraz na pragmatismus a odbornost, která se od zbylých dvou odlišuje ve vnímání míry závažnosti problému a skeptičtějším pohledem na nelegální status drog a související vymáhání práva. Aktéři sdílející tuto perspektivu definují užívání drog jako...
The assesment of trombocyte function by optical and impendance agregometry
Malíková, Lenka ; Stiborová, Marie (advisor) ; Poljaková, Jitka (referee)
Introduction: Platelets have an important role in the process of haemostasis in which they form blood clot generation. In some cases it is necessary to suppress activity of platelets by antiplatelet drugs to prevent life threatening states. Acetylsalicylic acid (ASA) and clopidogrel can influence the mechanism of primary haemostasis by inhibition of platelet function. This process has to be controlled. Clopidogrel is used for prevention of thrombotic states. The active form of clopidogrel is formed by cytochrome P450 3A4. Clopidogrel binds to the receptor P2Y12 instead of ADP, so platelets cannot be activated. The effect of clopidogrel is very variable. It is known that there is unresponsiveness to clopidogrel in 5-30 % patients. Acetylsalicylic acid acetylates cyclooxygenase and blocks the conversion of arachidonic acid to tromboxan A2, so platelets cannot be activated. ASA treatment is effective, but in some patients can appear so called aspirin resistance (AR). Possible unresponsiveness to the therapy is the reason why it is suitable to monitor antiplatelet therapy, which may be provided by various methods. Thesis target: To detect normal range in measurement of healthy control group, evaluate efficiency of clopidogrel and ASA and to determine which method (LTA - Light Transmission Aggregometry...
Analysis of stress field in the vicinity of fatigue crack in IPE made from stainless steel
Juhászová, Tereza ; Malíková, Lucie (referee) ; Seitl, Stanislav (advisor)
The master thesis is focused on analysis of stress field in the vicinity of stress concentration of stainless steel IPE beam loaded in tree point bending. Theoretical part includes introduction to fracture mechanics with basic terms, principles and variables used to describe fatigue behaviour of material. It concludes teoretical grounds of fracture tests which are future focus of the thesis, methodes used by numerical softwares and methodes used to obtain numerical results. Practical part includes comparision between two and three dimensional numerical models in three point bending, IPE model with different crack front shapes and plastic zone size. Numerical modelling was processed in Ansys Mechanical APDL. Thesis also involves results of experimental testing evaluated using numerical model.
The Influence of Specimen Thickness on Crack Initiation in the Tip of General Singular Stress Concentrator
Kopp, Dalibor ; Řoutil,, Ladislav (referee) ; Malíková, Lucie (referee) ; Klusák, Jan (advisor)
Geometrical discontinuities, like sharp notches, appear in constructions and engineering structures and lead to stress concentrations. These technical objects are very dangerous due to the fact that they reduce the structural conformity and can lead to crack initiation. Technical objects are not always designed as homogenous bodies but can consist of two or more materials with sharp notches on the interface of these materials. The influence of free surface on crack initiation conditions is studied and assessed by means of 3D model of sharp and bi-material notches with finite thickness. Stress fields around the singular stress concentrators are calculated with finite element method and the results are evaluated by means of criterion of critical quantity. This approach is easy applicable and can be used in combination with the knowledge of basic material properties and results of finite element analysis of the assessed notches. In order to estimate weather crack will initiate from the middle of the observed notched specimen or from its free surface, the value of averaged critical applied stress was introduced. With this value it’s possible to determine the location of crack initiation thru the sample thickness. Thru the ratio of values of critical applied stress in the middle and on the free surface of the observed specimen it’s possible to quantify the influence of the free surface on the location of crack initiation. With the use of this approach it’s shown, that the location of crack initiation depends on more parameters, loading direction, the notch opening angle and the sample thickness. In case of bi-material notches it depends also on the ratio of young modulus.
Numerical support for wedge splitting test on non-traditional geometry
Juhászová, Tereza ; Malíková, Lucie (referee) ; Seitl, Stanislav (advisor)
Bachelor thesis is focused on numerical support of wedge splitting test with non-traditional geometry. Numerical analysis takes place in program Ansys, defining behavior of models with modified entry parameters. Attention is focused on values of parameters characteristic for fracture mechanics; stress intensity factor and T-stress and functions describing their relationship to length of crack, evaluation of which is graphically illustrated.
Evaluation of fracture response of Silesian granite specimens via Effective Crack Model approach and finite element analysis
Malíková, L. ; Vavro, Leona ; Vavro, Martin ; Keršner, Z.
The paper is focused on the advanced evaluation of fracture tests of selected rock specimens. Assessment of fracture response of chevron notch cylindrical specimens of Silesian granite subjected to three-point bending test was performed. The effective crack model is used and academic software chevroncylinder (author Petr Frantík) based on the finite element method is applied for the analyses. Based on the described procedures, estimation of maximum values of the effective fracture toughness are established and discussed.

National Repository of Grey Literature : 34 records found   1 - 10nextend  jump to record:
See also: similar author names
5 MALÍKOVÁ, Lenka
5 Malíková, Lenka
1 Malíková, Lucia
8 Malíková, Lucie
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