• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 19
  • 2
  • 1
  • 1
  • Tagged with
  • 23
  • 23
  • 23
  • 14
  • 13
  • 8
  • 6
  • 6
  • 5
  • 5
  • 4
  • 4
  • 4
  • 3
  • 3
  • 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.
11

Intelligentes Nesting in der Kreislaufwirtschaft zur Steigerung der Ressourceneffizienz

Kronenberg, Philipp, Wieck, Franz, Weber, Sebastian, Löwer, Manuel 09 September 2021 (has links)
Kreislaufwirtschaft ist ein Konzept, um den Rohstoff- und Ressourcenverbrauch wirksam zu reduzieren. Hierbei sollen bestehende Produkte und Ressourcen so lange wie möglich in wertschöpfenden Kreisläufen gehalten werden. Im Rahmen der Repurpose (Wiederverwendung) Strategie werden Bauteile und Ressourcen von ausrangierten Produkten in neue Produkte mit anderer Funktion wiederverwendet. Hierzu müssen Rohlinge für neue Produkte in Sekundärrohstoffen angeordnet und herausgetrennt werden. Bedingt durch den nicht standardisierten Zustand von Sekundärrohstoffen, wird ein intelligentes Nesting Verfahren eingesetzt, die Ressourceneffizienz zu verbessern. Der Einsatz von intelligentem Nesting im Rahmen der Kreislaufwirtschaft zeigt, dass der Einsatz von Sekundärrohstoffen gesteigert und die benötigte Energie für die nachfolgenden Fertigungsverfahren eingespart werden kann.
12

Možnosti využití odkalů po vypírce vápence / The possibilities of use of sludges from limestone wash

Švec, Jiří January 2011 (has links)
In modern point of view of waste management is desirable to effectively process the grates possible amount of wastes. Sediments from cleaning of mined lime stones contains a lot of clay components, but there is also indispensable share of soft calcite. This composition makes these sediments a promising material for preparation of hydraulic binders. Production of common hydraulic binders, especially Portland cement, is very energy-intensive plus loads environment with considerable amount of combustion gases, therefore it is necessary to explore possibilities of alternative low - energy binders production and usage.
13

Studium možností separace chloridů z by-passových odprachů / Study on the possibilities of separation of chlorides from by-pass dust

Havelka, Jaroslav January 2017 (has links)
The thesis deals with the study and the characterization of bypass dusts from the cement plants. The aim of the thesis is to search for the possibilities of the usage of that secondary product by means of the cement production. The thesis focuses mainly on the determination of the amount of soluble substances in the dusts, the dependence of dissolution of the soluble share on water – dust ratio, the dependence of dissolution time on the yield of the soluble share and the influence of the temperature on the yield. The physical and chemical properties of the investigated samples taken from several cement plants in the Czech Republic and Slovakia were found out by using the following methods: by TG/DTA analysis, particles size by laser diffraction, phase composition of raw materials, treated raw materials and evaporation residues by X-ray diffraction. It was further investigated whether there was a link between finesse of the particles and the content of soluble substances (chlorides). This was accomplished by classification of the bypass dusts as fine and coarse fraction on the air cassifier with the target parameter X50 1 m. The aim of the classification was to find out whether some of the fractions carry majority share of some of components.
14

Vývoj lepicí hmoty pro instalaci čedičových prvků na silikátový podklad v náročných expozičních podmínkách / Development of adhesive material for the installation of basalt elements on silicate foundations under severe exposure conditions

Bergerová, Kamila January 2019 (has links)
The diploma thesis deals with research and subsequent development of a new adhesive material for the installation of nonabsorbent basalt elements on silicate foundations under severe exposure conditions. For commercially produced tile adhesives, only primary raw materials are used as fillers. The purpose of this work is to evaluate the possibility of utilization of secondary raw materials as fillers in the tile adhesive. The thesis is mainly focused on the durability of these materials after exposure to the aggressive environment.
15

Hodnocení zdravotních rizik vybraných faktorů pracovního prostředí a pracovnělékařských služeb v oblasti recyklace a zpracování druhotných surovin a odpadů / Health Risk Assessment of Selected Factors of Working Environment and Occupational Health Services in the Field of Recycling and Processing of Secondary Raw Materials and Waste

DVOŘÁKOVÁ, Sára January 2017 (has links)
This thesis deals with the evaluation of health risks of chosen factors in the work environment and medical services in the recycling and secondary raw materials and waste processing field. The goal of the thesis is to chart companies which handle recycling and secondary raw materials and waste processing in the South Bohemian Region, to find out the risk factors that go in hand with this work and to determine in which work category these workers belong. I have determined three hypotheses within the research. Hypothesis 1: The nature of the work activities does not correspond with suggested risks. Hypothesis 2: The workers are not equipped with tools in accordance with detected risks. Hypothesis 3: The workers of companies dealing with recycling and secondary raw materials and waste processing do not attend the necessary medical check-ups. The thesis consists of a theoretical and a practical part. In the theoretical part I have introduced the risk factors connected to recycling and secondary raw materials and waste processing. I have covered the problematics of medical services for the employees, occupational disease and the protection of health from unfavorable effects of the work environment. To reach my goal, I have utilized quantitative research methods. For data collecting I have used anonymous surveys in the area of the South Bohemian Region. In the survey, I have adressed scrapyards, composting plants, collection yards and waste dumps. The collected data were processed by the Microsoft Excel program. The obtained data may be used as an information source for students as well as for employers and employees in companies handling secondary raw materials and waste processing.
16

Využití rychle obnovitelných surovin ve výplňových hmotách / Utilization of quickly renewable materials in the filling materials

Keprdová, Šárka Unknown Date (has links)
Construction is a very dynamically developing industry that is placing ever greater demands on the properties of used building materials and structures built on them. In this context, there is a long-term trend to use construction materials made from natural quickly renewable raw materials. These tendencies are caused by natural reaction to the overly technological modern society, as well as efforts towards a greener approach in construction. In this sense, the natural materials from renewable sources means technologically processed organic material of plant origin. Dissertation focuses on the research and subsequent development of filling materials for vertical and horizontal structures based on quickly renewable materials. Pivotal quickly renewable raw material used in the production of filling material is technical hemp. Technical hemp is quickly renewable raw material with very good properties very similar to wood. Furthermore, the research focused on secondary raw materials, which partly replace the binder of the filling material. The resulting filling material has good physical-mechanical and thermo-technical characteristics.
17

Popílky jako surovinová základna budoucnosti / Ash – the raw material base for the future

Marko, Michal January 2018 (has links)
This master’s thesis responds to the worldwide problem concerning in the search of new material base for the future usage. Solid residues from high temperature or fluid coal combustion could be one of many alternatives to the raw materials. The study deals with the analysis of side energy products produced by power plant industry in the Czech Republic. Based on the fly ash chemical composition, possibilities of aluminium and even iron and titanium separation were proposed and then proved in the laboratory scale. Extracted components were separated selectively using apropriate methods. Then a couple of sintering reactions leading to improvement the leachability of selected elements from the fly ash matrix were carried out. Appropriate input material modification by high-temperature sintering reaction combined with extraction process in the sulfuric acid solution leads in dissolution up to 99 % of aluminium from the fluid and high-temperature fly ash.
18

Studium vývoje fázového složení v silikátových systémech dostupnými metodami a jejich optimalizace / Development of phase composition in silicate systems by available methods and their optimalization

Opravilová, Lenka January 2015 (has links)
One of the most prominent measurable parameters of the development of phases and phase transformations in inorganic systems are undoubtedly the volume changes of silicate matrix. The study of volume changes is crucial in the terms of usable durability of final product. They represent shrinkage or expansion of the material and may lead to significant decrease of technological and ecological parameters and often to complete destruction of these materials. Most often the volume changes can be observed when cement is used as a binder and in concretes, mortars, artificial aggregates and other similar materials. There are many methods to detect, define and determine the volume changes qualitatively or quantitatively. The development of phases was investigated as a part of the dissertation thesis and hence the volume changes were observed under the conditions closest to the real state in the construction industry. The raw materials and admixtures were selected which model the content of hazardous components present in conventional materials (both natural and secondary), used in construction and the relationship with volume changes was searched and demonstrated. The contacts for measuring the volume changes were attached to test surfaces of specimens and the physical - mechanical tests (volume changes, phase changes, strength, etc.), chemical analysis and ecotoxicity tests depending on the length of hydration were performed.
19

Vývoj progresivního kotevního materiálu na polymerní bázi / Development of progressive polymer anchor material

Žlebek, Tomáš January 2017 (has links)
The diploma thesis deals with development of a new progressive anchor material on the polymer base. Nowadays, it is effort to utilize secondary raw materials in building industry as much as possible both from an environmental aspects in order to save primary energy sources and the reduction of waste and also due to economic reasons. Therefore, there is an effort to utilize high amount of suitable and appropriately treated secondary raw materials into the anchor materials. The main aim of this work is to develop high quality anchor material characterized by excellent ratio between speed and strength growth, high chemical resistance, thermal resistance and particularly minimal shrinkage. This new material is designed especially for anchoring building structures heavy machines steel barriers and other elements.
20

Optimalizace složení dřevoplastových kompozitů s ohledem na jejich využití ve stavebnictví / The optimization of the wood polymer composite composition regarding its utilization in building structures

Benešová, Anna January 2017 (has links)
Wood-polymer composite is a relatively new type of material that combines shattered wood mass and a thermoplastic polymer. This material is utilized especially as an alternative to hard wood in the area of non-bearing exterior elements, as it reaches better properties in terms of the basic durability and low maintenance. Raw material composition and processing of the composite enable to provide a significant modification with further matters leading to an improvement of the end-product properties. Research and development in this field focuses predominantly on the utilization of such modifying additives that either enhance the resistance to weathering or are of the recycled nature, as a significant part of the raw material mixture comprises the constituent obtained from non-renewable resources. The aim of the thesis is the evaluation of the influence of the wood-polymer composite modification separately at two levels. First of them is the modification to matrix by using a recycled polymer, the second one comprises the modification of the wood flour with a secondary spherical filler. Both types of modified composites have been assessed in terms pf the prime characteristics and the resistance to adverse ambient.

Page generated in 0.0832 seconds