• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 69
  • 6
  • Tagged with
  • 75
  • 41
  • 14
  • 11
  • 10
  • 9
  • 8
  • 8
  • 8
  • 8
  • 6
  • 6
  • 5
  • 5
  • 5
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Kontaminace vybraných lokalit Ostravy těžkými kovy / The heavy metal contamination of selected sites in Ostrava

Mihočová, Silvie January 2011 (has links)
This thesis is focused on the assessment of contamination of non-agricultural soils of selected locations in Ostrava of hazardous metals. Selection of locations was based on the stationary pollution source REZZO1. Total 36 collected samples from 12 locations in three times periods between July 2010 and March 2011 that each collection represented a different time period for characteristic emissions conditions. The risk of metals mercury, cadmium, lead, copper and chromium were determined by atomic absorption spectrometry (F AAS, ET AAS, AMA 254).The influence of the distance of locations from stationary sources of REZZO1 on the extent of soil contamination by selected metals was confirmed.
62

Výskyt těžkých kovů v blízkosti dopravních komunikací v Brně / Presence of heavy metals in vicinity of the roads in Brno

Brzobohatý, Jan January 2011 (has links)
Diploma thesis deals with the risk assessment of metals in soils near roads in the city of Brno. For samples collection has been chosen twenty-five localities which were divided into five groups depending on the traffic load, in order to compare the impact of transport on the risk of soil contamination with metals. In the soil samples were determined levels of six hazardous metals (Cd, Hg, Pb, Zn, Ni, Cu). Lead, zinc, nickel and copper were determined by the flame atomic absorption spectrometry (F-AAS), cadmium by the electrotermic atomic absorption spectrometry (ET-AAS) and mercury by the advanced mercury analyzer AMA 254.
63

Použití scruberů při čištění vzduchu / Air contaminants separation process

Krištof, Ondřej January 2012 (has links)
The Diploma thesis is focused on the separation of gaseous pollutants from contaminated mixtures of gases into liquids using absorbent device. The theoretical part is mainly concerned with describing the absorption process, the method expression and the factors influencing the rate of transfer of contaminants between phases. The experimental part deals with the dependence of transfer of carbon dioxide contained in an air mixture into an aqueous solution of sodium hydroxide on the process conditions of separation in pilot scrubber.
64

Vliv skladovacích podmínek na metabolický profil jablek / Influence of Storage Conditions on Metabolic Profile of Apples

Duroňová, Kateřina January 2012 (has links)
The goal of presented dissertation has been complex analysis of changes in content of fatty acids, enzymatic and low-molecular antioxidants in apples and related evaluation of perception of originators of storage diseases for apples stored in various conditions. Main part of the work has been dedicated to study of the impact of storage of apples in modified atmosphere with reduced amount of oxygen and in reference “normal” atmosphere for six months. Next part of the work has been dedicated to study how apple storage in common, consumer affordable, conditions (storage in a cellar, in a refrigerator, and in room temperature) affects content of low-molecular antioxidants. For testing has been selected apple kinds Jonagored, Golden Delicious, Idared, Šampion, and Granny Smith. Within the scope of this work has been optimized the method for determination of fatty acids in plant material with higher content of wax. The measured values imply the apples are valuable source of many important nutrition substances like vitamins, provitamins and antioxidants. During the storage process these substances exhibit considerable protective function. Long-term storage, mainly in the atmosphere with reduced amount of oxygen (FAN), enables preservation of majority of these important nutrition substances depending on the kind of apple and conditions of storage. Freezing process is conservative to apples (mainly in the presence of protective substances), while in the process of drying the values of all monitored antioxidants decrease depending on temperature and conditions of drying. Upon the choice of the storage method one must consider nutrition, sensoric characteristic and consumer demands.
65

Vícestupňové stochastické programování s CVaR: modely, algoritmy a robustnost / Multi-Stage Stochastic Programming with CVaR: Modeling, Algorithms and Robustness

Kozmík, Václav January 2015 (has links)
Multi-Stage Stochastic Programming with CVaR: Modeling, Algorithms and Robustness RNDr. Václav Kozmík Abstract: We formulate a multi-stage stochastic linear program with three different risk measures based on CVaR and discuss their properties, such as time consistency. The stochastic dual dynamic programming algorithm is described and its draw- backs in the risk-averse setting are demonstrated. We present a new approach to evaluating policies in multi-stage risk-averse programs, which aims to elimi- nate the biggest drawback - lack of a reasonable upper bound estimator. Our approach is based on an importance sampling scheme, which is thoroughly ana- lyzed. A general variance reduction scheme for mean-risk sampling with CVaR is provided. In order to evaluate robustness of the presented models we extend con- tamination technique to the case of large-scale programs, where a precise solution cannot be obtained. Our computational results are based on a simple multi-stage asset allocation model and confirm usefulness of the presented procedures, as well as give additional insights into the behavior of more complex models. Keywords: Multi-stage stochastic programming, stochastic dual dynamic programming, im- portance sampling, contamination, CVaR
66

In-situ reduktivní dehalogenace / In-situ reductive dehalogenation

Dvořák, Petr January 2018 (has links)
This master thesis is focused on groundwater remediation of chlorinated ethylenes and methanes in the area of chemical factory Spolchemie in the Czech Republic, Ústí nad Labem city. For these purposes nano zero valent iron particles were used. For the remediation two separate applications of different types of particles together in suspension with tracer (lithium chloride), were carried out. The results from the first application were evaluated by the supervisor of this thesis and are briefly summarized and discussed together with the second application which was evaluated by the author of this thesis. Second application of particles was carried out in October 2015 and observed for 424 days. Observation consisted of monitoring of groundwater level, physical-chemical parameters and collection of water samples for the analysis of concentrations of chlorinated hydrocarbons, their degradation products and several chosen ions. Nanoiron particles had the assumed effect onto the physical-chemical parameters and reduction of contamination. The application of tracer had proven the expected groundwater flow and made a possibility to distinguish between the process of reductive dehalogenation and dilution caused by the injected water, the dilution did not exceeded 5 % in most monitored points. Other...
67

Persistentní organické polutanty v životním prostředí Jihomoravského kraje / Persistent Organic Pollutants in the Environment of the Southern Moravia Region

Lána, Radim January 2008 (has links)
Byla provedena studie bioakumulace POP v potravním řetězci a historických trendů hladin POP v sedimentech Brněnské přehrady. Současné úrovně kontaminantů byly stanoveny v jelci tloušti z řeky Svratky a rovněž byla posouzena hygienická kvalita ryb z rekreačního rybolovu. Současné úrovně POP v terestrickém ekosystému byly posouzeny pomocí analýz jehličí jako přirozeného indikátoru znečištění. Studium jedinců tří druhů dravých ptáků z ČR bylo zaměřeno na zhodnocení kontaminace těchto vrcholných predátorů POP. S pomocí analýz vybraných druhů ryb ze Záhlinických rybníků byl rovněž studován proces bioakumulace. Posouzení parametrů dvou moderních extrakčních technik a jejich využitelnosti pro izolaci POP z různých matric bylo námětem poslední části dizertace.
68

Hodnocení radiační zátěže pacientů a možnost vzniku a řešení radiačních mimořádných událostí na oddělení nukleární medicíny Nemocnice České Budějovice, a.s. / The evaluation of radiation burden of patients and the possibility of radiation emergence and management of emergencies at the nuclear medicine department of the Hospital České Budějovice, PLC

DAŇOVÁ, Kristína January 2019 (has links)
The aim of my thesis was to evaluate radiation consequences in patients, and to evaluate unusual occurrences stemming from radiation at the department of nuclear medicine in hospital Ceske Budejovice. In the theory part, I worked with professional literature, applicable laws and internal documentation provided by the department of nuclear medicine in hospital Ceske Budejovice Plc The thesis reacted to the need of the department of nuclear medicine (dept. NM) in hospital Ceske Budejovice to evaluate the optimisation of doses for the patients and set local diagnostic levels. Different organisations worldwide deal with the question of optimising radiation protection, and their recommendations and standards are used in the Czech Republic. For this purpose, it is necessary to know the real activity of radiopharmaceuticals applied in each examination and to conduct a forecast resulting in effective doses also based on CT scans. The thesis also evaluates the occurrence of special radiation events really experienced at the department of NM (nuclear medicine) in the hospital mentioned above, the reasons for these events happening and precautions preventing them from happening in future. The owner of the permission for this activity, meaning the use of the source of ionizing radiation, has the duty to keep all documentation and paperwork in accordance with the law regulating nuclear power, abide by the rules of good practices and the real state of allowed practice. The occurrence of unusual events is closely connected with the documentation - internal emergency plan and monitoring program. (Law 263/2016) Therefore, it was recommended to compare these to the actual state and to review them based on the facts found. The values of applied activities and effective doses found were compared to the values published in the last report from UNSCEAR in 2016 and national referential values published in the bill about radiation protection no 422/ 2016. All results were inputted into tables and graphs. It was found that the applied activities at the department of NM in hospital Ceske Budejovice are in agreement with the values presented in UNSCEAR report and that they are lower than the national referential levels, which shows that there is optimised state of radiation protection for patients. The occurrence of concrete unusual radiation events at the department of NM in hospital Ceske Budejovice and their analysis revealed certain shortcomings in the process and the absence of security elements needed while holding radioactive liquid waste in storage at the hospital. It was necessary to find and implement such precautions, which will prevent similar type of events in future. The thesis will be handed in to the person tending to the radiation protection for the use of evaluation and providing the protection at the department of NM at the hospital Ceske Budejovice and to enable the documentation to be completed for the allowed activity.
69

Systém zajištění provozuschopnosti věcných prostředků chemické a technické služby HZS Pardubického kraje / Securing operability system of resources in kind of chemical and technical service in the fire brigade of Pardubice region

KOŽENÝ, Petr January 2017 (has links)
The aim of the diploma thesis is to assess contamination by chemical substances of selected operating premises at the FRS stations of the Pardubice Region. Elevated contamination by dangerous dangerous chemical substances of the mentioned premises can be results of many factors, from technical to organisational ones, and as a final consequence of this, it may influence firefighters´ health negatively. The theoretical part of the thesis presents basic information about the organisation, duties and securing the operability of chemical and technical services material equipment. Furthermore, knowledge of possible risks of contamination of material equipment and about inspections of the chemicals in operating environment are presented. In the survey part, air contamination of 13 selected areas is assessed during everyday operations and once in an intentionally contaminated area. As the measuring procedure in all the selected areas, air sampling through adsorption tube with Tenax sorbent was used. Specifying the chemical substances in the samples is implemented by the means of a thermodesorption equipment and a gas chromatograph with a mass spectrometer. Furthermore, sampling in sample bags with following analysis by the means of infrared spectroscopy is implemented in contaminated areas. There are 42 air sampling in Tenax adsorption tubes and 2 air sampling in sample bags implemented altogether. Numbers of volatile organic substances is identified in the surveyed areas, most of them benzene and toluene. From identified inorganic gases hydrogen sulfide is discovered in one case, which concentration exceeded strongly the hygienic standards set by the Czech legislation. The identified results not only can influence securing the operability of material equipment but also contribute to a general reduction of firefighters´ exposure to dangerous chemical substances.
70

Indexy znečištění pro hodnocení půd / Assessment of soils using pollution indices

Satola, Ondřej January 2020 (has links)
Subject of this diploma thesis is analysis of selected heavy metals in soils which are exposed to long-time cause of contaminants from metallurgical industry in localities Třinec and Ostrava. For assessment of the contamination, indexes for evaluation of soils were chosen. Those indexes are focusing mainly on rate of enrichment of the soils by selected heavy metals and resulting ecological and possibly health risk for human organism. Within every location, 26 samples were extracted, while every sample extract location, were selected to map the level of pollution around metallurgical plants in the most complex way. The analysis of the samples was done by techniques F-AAS and AMA 254 and established metals were mercury, lead, copper, chrome, nickel, manganese and zinc.

Page generated in 0.4505 seconds