HYBRID PolyHIPE MATERIALSSebastijan Kovačič
, 2011, dissertation
Abstract: A new class of polyHIPE materials has been prepared using high internal phase emulsions (HIPEs) with monomers in both phases. Resulting materials, namely hybrid polyHIPE materials, are obtained consisting of hydrophobic matrix (consisted of styrene cross-linked with DVB or dicyclopentadiene) filled with hydrophilic polymer gel (polyacrylic acid or polyNIPAM) and exhibit morphology changes according to pH and temperature of the surrounding medium. Our focus with regards to the production of hybrid polyHIPE materials was the responsiveness of such materials used for flow control. This property is beneficial for controlling the flow of the solution through the monolithic polymers. Furthermore, polyHIPE materials have also been prepared by using ring opening metathesis polymerisation of monomers, such as dicyclopentadiene and norbornene. Obtained materials have Young’s moduli in the range of hundred times higher than standard polyHIPE materials with the same level of porosity which represents a very important improvement in the development of highly porous cellular polymeric materials.
Keywords: emulsions, high internal phase emulsions, polymers, polyHIPEs, hybrid, hybrid polyHIPE materials, ROMP, flow-through, styrene, DVB, acrylic acid, NIPAM
Published: 04.05.2011; Views: 2315; Downloads: 208
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STRUCTURING OF SOL-GEL FUNCTIONALIZED CELLULOSE HYBRID MATERIALS AND THEIR CHARACTERIZATIONHeike M. A. Ehmann
, 2012, doctoral dissertation
Abstract: The goal of this thesis is the structuring of cellulose nanocrystals using different organofunctional silane compounds and different cationic species to prepare highly functional materials with tailored properties. In addition different new aspects and approaches for the structural characterization of functionalised cellulose nanocrystals (CNC) functionalised with different organofunctionalalkoxysilanes as well as cationic species have been introduced.
Cellulose nanocrystals (CNC) are prepared using three different acidic conditions to hydrolyse microcrystalline cellulose (MCC). The sulphuric acid hydrolysis introduces highly negative charged sulphate groups on the CNC. The aqueous nanocrystalline cellulose suspensions (aNCS) are analysed in terms of ζ-potential related to the pH and concentration to investigate the stability while dynamic light scattering (DLS) is used to investigate the size distribution. The hydrochloric acid hydrolysis in contrast only removes the amorphous regions but the so obtained CNC are less stabilized (decreased ζ-potential) and tend to agglomerate very fast. The use of the mixture of both acids (HCl and H2SO4) during the hydrolysis of MCC introduces less sulphate groups compared with the sulphuric acid hydrolysis. AFM investigations show that the shapes of the CNC are highly influenced by the hydrolysis conditions. While the shape of the H2SO4 hydrolysed CNC is rod like, while the shape of the other two CNC samples is more spherical in nature. One of the major topic in this work is the analysis of aNCS in aqueous solutions by small angle x-ray scattering (SAXS). The use of the generalized indirect Fourier transformation (GIFT) method allows the analysis of these systems and structural properties such as shape, size and surface charge of aNCS can be assessed. Using this kind of characterisation it can be seen that the shape of the H2SO4 hydrolysed CNC is definitely rod like while the other CNC sample can be described with spheres. In addition to the aNCS characterisation different substrates (Si-wafer, glass slides, polystyrene, etc.) are equipped with aNCS using a variety of different deposition methods (e.g. spin coating, solution casting, dip coating). The resulting films are studied in terms of morphology AFM, SARFUS and SEM. Sophisticated scattering techniques are employed for surface structural characterisation as grazing incidence small angel x-ray scattering. The determination of surface free energies allows conclusions about the hydrophilicity and hydrophobicity as well as the interaction capacity with different liquids. It can be seen that besides the hydrophilic nature of the CNC also hydrophobic interactions are present. The highly negative charged CNC sample which was prepared using sulphuric acid hydrolysis is found to be best suitable for the further hybridization with different organofunctional silanes and for the layer by layer approach (LBL) with different cationic species.
The organofunctionalalkoxysilanes which were used in this study can be divided into three groups (e.g filler, surface functionalisation silanes, cross linking silanes). Depending on the nature of the organic residue the silanes are capable to introduce functionalities with enhanced hydrophobic and olephobic properties. The surface energies are investigated using contact angle method, while the surface energies are calculated using three different model approaches (OWRK, Wu, Acid-Base). The most increased hydrophobic and oleophobic properties were measured for trimethylfluorophenylsilantriol (PFTEOS). The morphology of the coated silanes is investigated using SAFRUS technique. It can be seen that nearly all silanes can be coated as homogeneous films onto different substrates (Si-wafer, SURFs, glass slides) with different methods (spin coating, solution casting). The macroscopic appearance of solution casted silanes is investigated using optical microscopy. The differences of the structural nature of the so obtained coatings and detaching films were investigated...
Keywords: Cellulose nanocrystals, sol-gel chemistry, organofunctionalalkoxysilanes, hybrid materials, small angle x-ray scattering, generalized indirect Fourier Transformation, quartz crystal microbalance dissipation, surface free energy, surface functionalisation, layer by layer
Published: 28.11.2012; Views: 1618; Downloads: 98
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A modular hybrid approach to employee timetablingDrago Bokal
, Gašper Fijavž
, Bor Harej
, Andrej Taranenko
, Klemen Žagar
, 2008, published scientific conference contribution
Abstract: We consider a classical employee timetabling problem: a set of employees with various skill levels, qualifications, workload and availability distributions has to be assigned to a set of shifts, each requiring a prescribed number of qualified employees and spanning a given time period. The novelty of our approach is a hybrid combination of the methods proposed in bibliography, such that we leverage the advantages of known methods while minimizing their disadvantages. Thus, we first apply the generalized local hill-climbing with randomized neighborhoods to quickly reach the vicinity of local optima, and then use the tabu search to explore more of the search space around those solutions. Our experiments show that the resulting hybrid technique performs better than the comparable approaches presented in bibliography due to the hybrid nature of the technique. In addition, we propose a modular design that utilizes dependency injection to compose the the search algorithm. Together with careful modeling, this approach allows for constant-time evaluation of each possible step in the neighborhood and for an easy evaluation of different hybrid combinations that can be combined and parameterized at runtime.
Keywords: operacijsko raziskovanje, razporejanje zaposlenih, urniki, lokalna optimizacija, operations research, employee timetabling, generalized local hill-climbing, tabu search, hybrid local optimization
Published: 10.07.2015; Views: 289; Downloads: 32
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Impact of hybrid queing disciplines on the VoIP traffic delaySaša Klampfer
, Jože Mohorko
, Žarko Čučej
, 2009, original scientific article
Abstract: Impact of hybrid queuing disciplines on the VoIP traffic delay
Keywords: hibridne metode, načini uvrščanja, VoIP, zakasnitev, ožičeno omrežje, hybrid methods, queuing disciplines, VoIP, delay, wired network
Published: 10.07.2015; Views: 546; Downloads: 5
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Educationa Park - Technical Academy MariborSamanta Rebernak
, 2016, master's thesis
Abstract: The Educational Park - Technical Academy Maribor is a new concept with which we wish to enrich the city of Maribor. The main idea is to connect research and education with practical experience, start up companies and the production spaces of big companies. This broad content with multiple additions could be placed in the Business Industrial Zone Tezno, with certain modifications to the existing structures.
This thesis deals with the evolution of industrial architecture and especially its importance to the city of Maribor. We present an in depth historical analysis of the company TAM, the predecessor of today’s BIZ Tezno, which was one of the biggest factories with research facilities and educational spaces in the former Yugoslavia.
The urban master plan consists of the placement of the afore-mentioned content in the facilities of BIZ Tezno. The idea is to create an open, inviting space that would be a part of city life, with the addition of sports facilities, pool areas, a museum of industrial heritage, a concert hall, etc.
As a continuation of the master plan, we also designed an industrial architectural model that shows how the concept of the Educational park can be implemented in the facilities of an established company. We also contemplated the use of renewable materials and, therefore, used timber in the construction. The facility would be an addition to the brand image of any company that values sustainable development and progress.
Keywords: degraded urban areas, brownfield, converting a factory complex, Maribor industrial heritage, TAM, industrial architecture, Science park, Technology Park, Industrial Park, Timber construction, Timber hybrid construction
Published: 20.04.2016; Views: 1039; Downloads: 111
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Hybrid Web Application Development Using Meteor.js FrameworkNejc Burič Novačan
, 2016, undergraduate thesis
Abstract: This Thesis work shows one of many possible ways of developing hybrid web applications. In the theoretical part, we described the Meteor.js framework and MongoDB database, which we used for realization of the web application. In the presentation of the framework, new and modern methods are described which are used in modern web programming. The hybrid web application which we developed in the practical part enables the user to navigate to tourist attractions in Slovenia. It enables the user to discover and locate natural landmarks, rural tourism, clubs, electric car charging stations, places of interest,, and Tourist Information Centres. Admin can regulate the points of interest with the help of Google API. The application also displays current distances to every point of interest and notifies the users about the changes made by the administrator.
Keywords: web programming, hybrid applications, Meteor.js, MongoDB
Published: 22.09.2016; Views: 956; Downloads: 65
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Hybrid societies: challenges and perspectives in the design of collective behavior in self-organizing systemsHeiko Hamann
, Yara Khaluf
, Jean Botev
, Mohammad Divband Soorati
, Eliseo Ferrante
, Oliver Kosak
, Jean-Marc Montanier
, Sanaz Mostaghim
, Richard Redpath
, Jon Timmis
, Frank Veenstra
, Mostafa Wahby
, Aleš Zamuda
, 2016, original scientific article
Abstract: Hybrid societies are self-organizing, collective systems, which are composed of different components, for example, natural and artificial parts (bio-hybrid) or human beings interacting with and through technical systems (socio-technical). Many different disciplines investigate methods and systems closely related to the design of hybrid societies. A stronger collaboration between these disciplines could allow for re-use of methods and create significant synergies. We identify three main areas of challenges in the design of self-organizing hybrid societies. First, we identify the formalization challenge. There is an urgent need for a generic model that allows a description and comparison of collective hybrid societies. Second, we identify the system design challenge. Starting from the formal specification of the system, we need to develop an integrated design process. Third, we identify the challenge of interdisciplinarity. Current research on self-organizing hybrid societies stretches over many different fields and hence requires the re-use and synthesis of methods at intersections between disciplines. We then conclude by presenting our perspective for future approaches with high potential in this area.
Keywords: hybrid society, bio-hybrid, distributed, self-organization, design, intedisciplinary
Published: 10.07.2017; Views: 455; Downloads: 236
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Efficient copper removal from an aqueous anvironment using a novel and hybrid nanoadsorbent based on derived-polyethyleneimine linked to silica magnetic nanocompositesOlivija Plohl
, Matjaž Finšgar
, Sašo Gyergyek
, Urban Ajdnik
, Irena Ban
, Lidija Fras Zemljič
, 2019, original scientific article
Keywords: environmental nanotechnology, nanoparticle characterization, surface analysis, magnetic polymer nanosorbents, heavy metal reduction, hybrid nanocomposites
Published: 25.02.2019; Views: 483; Downloads: 169
Full text (4,36 MB)