142 resultados para saturated porous media


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Summary: Pedagogics and media : multidisciplinary aspects for the innovative development of LIS education

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UMTS is a 3rd generation telecommunication system, which introduces new network architecture. The change in the network architecture introduces new logical network nodes and changes the role of existing nodes in the network. This architecture changes the current vertically specialized network into a horizontally layered structure. In practice, the layering means that different levels in network hierarchy are separated, and they communicate over well-specified interfaces. The Connectivity Layer, at the bottom of the UMTS network architecture, contains Media Gateways (MGW). The GSM radio access network and UMTS access network are connected to the connectivity network via a MGW. External networks, e.g. ISDN networks, are accessed via other MGWs. The user plane is transported across the connectivity network between/via MGWs. ATM network is used as the backbone in Ericsson’s UMTS core network release 2.0. The main goal of this thesis is to study how the MGW is used to bridge ATM and TDM networks. The Circuit Emulation Service (CES) for ATM is studied, as the conversion from TDM to ATM is made according it. The transportation is made using AAL2 and the issues that it has with voice traffic are studied. The implementation and usage of TDM switching service in MGW are described in detail.

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Työssä tutkitaan, kuinka Symbian käyttöjärjestelmälle voidaan tehdä siirrettäviä ohjelmia. Työssä käydään läpi menetelmiä, jotka helpottavat ohjelmistojen siirrettävyyttä uudelle alustalle. Uuteen älypuhelimeen voi tulla monia uusia komponentteja. Laite voi muuttua piiritasolla, käyttöjärjestelmästä voi tulla uusi versio sekä siirrettävästä ohjelmasta voi tulla uusi versio. Kaikki nämä vaikuttavat ohjelman siirrettävyyteen. Työssä tehtiin Java-rajapinnan siirto uudelle alustalle. Prosessin aikana löydettiin tärkeitä tekijöitä, jotka vaikuttavat ohjelmiston siirrettävyyteen. Siirrettävyys sinänsä pitäisi ottaa huomioon ohjelmistoprosessin jokaisessa vaiheessa. Älypuhelimista tulee jatkuvasti uusia versioita. Tämä tekee ohjelmien siirrettävyydestä hyvin tärkeän tekijän ohjelmistojen suunnittelussa. Hyvin suunniteltu ohjelma on helpompi ylläpitää, päivättää ja siirtää myöhemmin.

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Tavoitteena on tutkia mitä mahdollisuuksia Internet tarjoaa business-to-business markkinointiviestintään. Tämä tutkimus on tyypiltään deskriptiivinen case-tutkimus, jossa casen avulla saadaan käytännön esimerkki siitä miten eräs yritys on käytännössä hyödyntänyt Internetiä markkinointiviestinnässään. Case toteutettiin puhelin-, sähköposti- ja henkilökohtaisilla haastatteluilla. Internet tarjoaa markkinointiviestinnälle sekä haasteen että mahdollisuuden. Se tarjoaa markkinoijalle käyttöön sekä uudentyyppisen median että mahdollisuuden suoriin markkinakontakteihin. Internet-markkinointi pohjautuu perinteisiin markkinoinnin konsepteihin, erottuen yhden tärkeän ominaisuuden, interaktiivisuuden, perusteella. Koska näin yritys pääsee suoraan kommunikoimaan asiakkaidensa kanssa, se saa jatkuvasti tietoja, joiden avulla yritys voi paremmin suunnitella markkinointistrategiaansa ja kohdentaa markkinointiviestintäänsä tarkasti asiakkaiden tarpeiden mukaan.

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Abstract: A bouble-faced medium? The challenges and opportunities of the Internet for social movements

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The objective of this thesis is to shed light on the vertical vibration of granular materials for potential interest in the power generation industry. The main focus is investigating the drag force and frictional resistance that influence the movement of a granular material (in the form of glass beads) contained in a vessel, which is subjected to sinusoidal oscillation. The thesis is divided into three parts: theoretical analysis, experiments and computer simulations. The theoretical part of this study presents the underlying physical phenomena of the vibration of granular materials. Experiments are designed to determine fundamental parameters that contribute to the behavior of vibrating granular media. Numerical simulations include the use of three different software applications: FLUENT, LS-DYNA and ANSYS Workbench. The goal of these simulations is to test theoretical and semiempirical models for granular materials in order to validate their compatibility with the experimental findings, to assist in predicting their behavior, and to estimate quantities that are hard to measure in laboratory.

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Streaming potential measurements for the surface charge characterisation of different filter media types and materials were used. The equipment was developed further so that measurements could be taken along the surfaces, and so that tubular membranes could also be measured. The streaming potential proved to be a very useful tool in the charge analysis of both clean and fouled filter media. Adsorption and fouling could be studied, as could flux, as functions of time. A module to determine the membrane potential was also constructed. The results collected from the experiments conducted with these devices were used in the study of the theory of streaming potential as an electrokinetic phenomenon. Several correction factors, which are derived to take into account the surface conductance and the electrokinetic flow in very narrow capillaries, were tested in practice. The surface materials were studied using FTIR and the results compared with those from the streaming potentials. FTIR analysis was also found to be a useful tool in the characterisation of filters, as well as in the fouling studies. Upon examination of the recorded spectra from different depths in a sample it was possible to determine the adsorption sites. The influence of an external electric field on the cross flow microflltration of a binary protein system was investigated using a membrane electroflltration apparatus. The results showed that a significant improvement could be achieved in membrane filtration by using the measured electrochemical properties to help adjust the process conditions.

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The development of load-bearing osseous implant with desired mechanical and surface properties in order to promote incorporation with bone and to eliminate risk of bone resorption and implant failure is a very challenging task. Bone formation and resoption processes depend on the mechanical environment. Certain stress/strain conditions are required to promote new bone growth and to prevent bone mass loss. Conventional metallic implants with high stiffness carry most of the load and the surrounding bone becomes virtually unloaded and inactive. Fibre-reinforced composites offer an interesting alternative to metallic implants, because their mechanical properties can be tailored to be equal to those of bone, by the careful selection of matrix polymer, type of fibres, fibre volume fraction, orientation and length. Successful load transfer at bone-implant interface requires proper fixation between the bone and implant. One promising method to promote fixation is to prepare implants with porous surface. Bone ingrowth into porous surface structure stabilises the system and improves clinical success of the implant. The experimental part of this work was focused on polymethyl methacrylate (PMMA) -based composites with dense load-bearing core and porous surface. Three-dimensionally randomly orientated chopped glass fibres were used to reinforce the composite. A method to fabricate those composites was developed by a solvent treatment technique and some characterisations concerning the functionality of the surface structure were made in vitro and in vivo. Scanning electron microscope observations revealed that the pore size and interconnective porous architecture of the surface layer of the fibre-reinforced composite (FRC) could be optimal for bone ingrowth. Microhardness measurements showed that the solvent treatment did not have an effect on the mechanical properties of the load-bearing core. A push-out test, using dental stone as a bone model material, revealed that short glass fibre-reinforced porous surface layer is strong enough to carry load. Unreacted monomers can cause the chemical necrosis of the tissue, but the levels of leachable resisidual monomers were considerably lower than those found in chemically cured fibre-reinforced dentures and in modified acrylic bone cements. Animal experiments proved that surface porous FRC implant can enhance fixation between bone and FRC. New bone ingrowth into the pores was detected and strong interlocking between bone and the implant was achieved.

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Invocatio: kreik.

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Ceramics are widely used in industrial applications due to their advantageous thermal and mechanical stability. Corrosion of ceramics is a great problem resulting in significant costs. Coating is one method of reducing adversities of corrosion. There are several different thin film deposition processes available such as sol-gel, Physical and Chemical Vapour Deposition (PVD and CVD). One of the CVD processes, called Atomic Layer Deposition (ALD) stands out for its excellent controllability, accuracy and wide process capability. The most commonly mentioned disadvantage of this method is its slowness which is partly compensated by its capability of processing large areas at once. Several factors affect the ALD process. Such factors include temperature, the grade of precursors, pulse-purge times and flux of precursors as well as the substrate used. Wrongly chosen process factors may cause loss of self-limiting growth and thus, non-uniformities in the deposited film. Porous substrates require longer pulse times than flat surfaces. The goal of this thesis was to examine the effects of ALD films on surface properties of a porous ceramic material. The analyses applied were for permeability, bubble point pressure and isoelectric point. In addition, effects of the films on corrosion resistance of the substrate in aqueous environment were investigated. After being exposured to different corrosive media the ceramics and liquid samples collected were analysed both mechanically and chemically. Visual and contentual differences between the exposed and coated ceramics versus the untreated and uncoated ones were analysed by scanning electron microscope. Two ALD film materials, dialuminium trioxide and titanium dioxide were deposited on the ceramic substrate using different pulse times. The results of both film materials indicated that surface properties of the ceramic material can be modified to some extent by the ALD method. The effect of the titanium oxide film on the corrosion resistance of the ceramic samples was observed to be fairly small regardless of the pulse time.