63 resultados para Phase change material (PCM)


Relevância:

30.00% 30.00%

Publicador:

Resumo:

[Abstract]

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Työssä tarkasteltiin paikallisen teleyhtiön muutos- ja sopeuttamisprosessia vanhanaikaisesta puhelinyhtiöstänykyajan moderniksi teletoimijaksi. Selvitettiin, miten kaikki on saanut alkunsa ja minkälainen yritys on tänä päivänä. Yrityksen kehitykseen vaikuttaa väkisinkin organisaatiokulttuuri ja sen muuttuminen yrityksen toiminnan laajentuessa jamuuttuessa. Käytiin läpi orgäanisaatioteoriaa sekä siihen olennaisena osana liittyvää yrityksen arvomaailmaa ja yrityskuvaa. Tutkimus suoritettiin aikasarjana.Tutkimuksessa suoritettiin lyhyt historiakuvaus, jonka avulla selvitettiin tämän päivän kehitykseen vaikuttavat tekijät. Niitä olivat pääsääntöisesti yleinen teleliikennetoimialan kehittyminen ja viranomaisvalvonta. Asiaa tutkittiin kulttuurin kasvu- ja kehitysvaiheet menetelmää avuksi käyttäen. Empiirisenä aineistonakäytettiin paikallisen teleyhtiön vuosikertomuksia, otoksia julkisista lehti- ja internetartikkeleista sekä paikallisesta teleyhtiöstä ja yleisesti telealasta kertovaa kirjallisuutta. Lisäksi käytettiin hyväksi tutkijan omaa kokemusta pitkään telealalla työskennelleenä. Tutkimuksessa päädyttiin siihen tulokseen, että paikallisen teleyhtiön pitäisi näkyä enemmän valtakunnallisesti. Henkilöstön sopeuttaminen uuteen tilanteeseen tulee olemaan yritysjohdolle tärkein tehtävä. Tässä asiassa edesauttaa se, että yritysjohdolta löytyisi hyvät muutos-johtamisen ja vuorovaikuttamisen taidot. Viestinnän merkitys nousee myös erittäin tärkeäksi.Sen pitää toimia kumpaankin suuntaan, henkilöstön ja yritysjohdon välillä pitääolla kahdensuuntaista viestintää. Lisäksi todettiin, että todennäköisesti tapahtuu fuusioitumista joko niin, että isommat paikalliset teleyhtiöt ostavat pieniäyhtiöitä, ja markkinoille jää vain muutama iso paikallinen teleyhtiö, tai sitten kaikki paikalliset teleyhtiöt fuusioituvat yhteen isoon yhtiöön. Tulevaisuudessa kilpailun kiristyminen tulee luomaan tämänkaltaisia paineita. Tuote- ja palvelukehitykseen pitää tulevaisuudessa panostaa huomattavasti enemmän. Telealalla saadaan myös tottua siihen, että EU:n alueella tullaan vaatimaan kilpailun täyttävapautumista. Lisäksi viranomaiset tulevat seuraamaan telealaa jatkossakin erittäin tarkasti.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In this thesis, the sorption and elastic properties of the cation-exchange resins were studied to explain the liquid chromatographic separation of carbohydrates. Na+, Ca2+ and La3+ form strong poly(styrene-co-divinylbenzene) (SCE) as well as Na+ and Ca2+ form weak acrylic (WCE) cation-exchange resins at different cross-link densities were treated within this work. The focus was on the effects of water-alcohol mixtures, mostly aqueous ethanol, and that of the carbohydrates. The carbohydrates examined were rhamnose, xylose, glucose, fructose, arabinose, sucrose, xylitol and sorbitol. In addition to linear chromatographic conditions, non-linear conditions more typical for industrial applications were studied. Both experimental and modeling aspectswere covered. The aqueous alcohol sorption on the cation-exchangers were experimentally determined and theoretically calculated. The sorption model includes elastic parameters, which were obtained from sorption data combined with elasticity measurements. As hydrophilic materials cation-exchangers are water selective and shrink when an organic solvent is added. At a certain deswelling degree the elastic resins go through glass transition and become as glass-like material. Theincreasing cross-link level and the valence of the counterion decrease the sorption of solvent components in the water-rich solutions. The cross-linkage or thecounterions have less effect on the water selectivity than the resin type or the used alcohol. The amount of water sorbed is higher in the WCE resin and, moreover, the WCE resin is more water selective than the corresponding SCE resin. Theincreased aliphatic part of lower alcohols tend to increase the water selectivity, i.e. the resins are more water selective in 2-propanol than in ethanol solutions. Both the sorption behavior of carbohydrates and the sorption differences between carbohydrates are considerably affected by the eluent composition and theresin characteristics. The carbohydrate sorption was experimentally examined and modeled. In all cases, sorption and moreover the separation of carbohydrates are dominated by three phenomena: partition, ligand exchange and size exclusion. The sorption of hydrophilic carbohydrates increases when alcohol is added into the eluent or when carbohydrate is able to form coordination complexes with the counterions, especially with multivalent counterions. Decreasing polarity of the eluent enhances the complex stability. Size exclusion effect is more prominent when the resin becomes tighter or carbohydrate size increases. On the other hand,the elution volumes between different sized carbohydrates decreases with the decreasing polarity of the eluent. The chromatographic separation of carbohydrateswas modeled, using rhamnose and xylose as target molecules. The thermodynamic sorption model was successfully implemented in the rate-based column model. The experimental chromatographic data were fitted by using only one adjustable parameter. In addition to the fitted data also simulated data were generated and utilized in explaining the effect of the eluent composition and of the resin characteristics on the carbohydrate separation.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Tämän tutkielman tarkoituksena on selvittää suomalaisen kartonkikuljetuspakkausfirman, Eltete TPM Oy:n, tulevaisuudennäkymät selvittämällä voiko puisen kuljetuspakkausmateriaalin korvata kartonkisilla materiaaleilla. Kyseinen tutkimus suoritetaan selvittämällä toimialanmuutokseen vaikuttavia tekijöitä kuten ostokäyttäytymistä, innovaation ominaisuuksia, säädöksiä, kilpailuympäristöä sekä lopuksi tutkimalla mitä kuljetuspakkauksien asiakkaat haluavat ja tarvitsevat. Kyseisen tutkimuksen kohdeasiakkaiksi valittiin suurimmat kodinkoneyritykset Euroopassa ja tutkimusmenetelmäksi postikysely. Suoritetun markkinointitutkimuksen tulokset kodinkoneyritysten pakkausratkaisuista sekä kilpailija-analyysi osoittivat, että todella on olemassa kasvava kysyntä kierrätettäville kartonkisille kuljetuspakkausratkaisuille, kuten Eltete TPS - Framepack solution on, sekä että Eltete TPM Oy:llä on voimavaroja tulevaisuudessa nousta markkinajohtajaksi muuttuvalla kuljetuspakkaussektorilla.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Substances emitted into the atmosphere by human activities in urban and industrial areas cause environmental problems such as air quality degradation, respiratory diseases, climate change, global warming, and stratospheric ozone depletion. Volatile organic compounds (VOCs) are major air pollutants, emitted largely by industry, transportation and households. Many VOCs are toxic, and some are considered to be carcinogenic, mutagenic, or teratogenic. A wide spectrum of VOCs is readily oxidized photocatalytically. Photocatalytic oxidation (PCO) over titanium dioxide may present a potential alternative to air treatment strategies currently in use, such as adsorption and thermal treatment, due to its advantageous activity under ambient conditions, although higher but still mild temperatures may also be applied. The objective of the present research was to disclose routes of chemical reactions, estimate the kinetics and the sensitivity of gas-phase PCO to reaction conditions in respect of air pollutants containing heteroatoms in their molecules. Deactivation of the photocatalyst and restoration of its activity was also taken under consideration to assess the practical possibility of the application of PCO to the treatment of air polluted with VOCs. UV-irradiated titanium dioxide was selected as a photocatalyst for its chemical inertness, non-toxic character and low cost. In the present work Degussa P25 TiO2 photocatalyst was mostly used. In transient studies platinized TiO2 was also studied. The experimental research into PCO of following VOCs was undertaken: - methyl tert-butyl ether (MTBE) as the basic oxygenated motor fuel additive and, thus, a major non-biodegradable pollutant of groundwater; - tert-butyl alcohol (TBA) as the primary product of MTBE hydrolysis and PCO; - ethyl mercaptan (ethanethiol) as one of the reduced sulphur pungent air pollutants in the pulp-and-paper industry; - methylamine (MA) and dimethylamine (DMA) as the amino compounds often emitted by various industries. The PCO of VOCs was studied using a continuous-flow mode. The PCO of MTBE and TBA was also studied by transient mode, in which carbon dioxide, water, and acetone were identified as the main gas-phase products. The volatile products of thermal catalytic oxidation (TCO) of MTBE included 2-methyl-1-propene (2-MP), carbon monoxide, carbon dioxide and water; TBA decomposed to 2-MP and water. Continuous PCO of 4 TBA proceeded faster in humid air than dry air. MTBE oxidation, however, was less sensitive to humidity. The TiO2 catalyst was stable during continuous PCO of MTBE and TBA above 373 K, but gradually lost activity below 373 K; the catalyst could be regenerated by UV irradiation in the absence of gas-phase VOCs. Sulphur dioxide, carbon monoxide, carbon dioxide and water were identified as ultimate products of PCO of ethanethiol. Acetic acid was identified as a photocatalytic oxidation by-product. The limits of ethanethiol concentration and temperature, at which the reactor performance was stable for indefinite time, were established. The apparent reaction kinetics appeared to be independent of the reaction temperature within the studied limits, 373 to 453 K. The catalyst was completely and irreversibly deactivated with ethanethiol TCO. Volatile PCO products of MA included ammonia, nitrogen dioxide, nitrous oxide, carbon dioxide and water. Formamide was observed among DMA PCO products together with others similar to the ones of MA. TCO for both substances resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide and water. No deactivation of the photocatalyst during the multiple long-run experiments was observed at the concentrations and temperatures used in the study. PCO of MA was also studied in the aqueous phase. Maximum efficiency was achieved in an alkaline media, where MA exhibited high fugitivity. Two mechanisms of aqueous PCO – decomposition to formate and ammonia, and oxidation of organic nitrogen directly to nitrite - lead ultimately to carbon dioxide, water, ammonia and nitrate: formate and nitrite were observed as intermediates. A part of the ammonia formed in the reaction was oxidized to nitrite and nitrate. This finding helped in better understanding of the gasphase PCO pathways. The PCO kinetic data for VOCs fitted well to the monomolecular Langmuir- Hinshelwood (L-H) model, whereas TCO kinetic behaviour matched the first order process for volatile amines and the L-H model for others. It should be noted that both LH and the first order equations were only the data fit, not the real description of the reaction kinetics. The dependence of the kinetic constants on temperature was established in the form of an Arrhenius equation.

Relevância:

30.00% 30.00%

Publicador:

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The purpose of this dissertation is to examine the dynamics of the socio-technical system in the field of ageing. The study stems from the notion that the ageing of the population as a powerful megatrend has wide societal effects, and is not just a matter for the social and health sector. The central topic in the study is change: not only the age structures and structures of society are changing, but also at the same time there is constant development, for instance, in technologies, infrastructures and cultural perceptions. The changing concept of innovation has widened the understanding of innovations related to ageing from medical and assistive technological innovations to service and social innovations, as well as systemic innovations at different levels, which means the intertwined and co-evolutionary change in technologies, structures, services and thinking models. By the same token, the perceptions of older people and old age are becoming more multi-faceted: old age is no longer equated to illnesses and decline, but visions of active ageing and a third age have emerged, which are framed by choices, opportunities, resources and consumption in later life. The research task in this study is to open up the processes and mechanisms of change in the field of ageing, which are studied as a complex, multi-level and interrelated socio-technical system. The question is about co-effective elements consisting of macro-level landscape changes, the existing socio-technical regime (the rule system, practices and structures) and bottom-up niche-innovations. Societal transitions do not account for the things inside the regime alone, or for the long-term changes in the landscape, nor for the radical innovations, but for the interplay between all these levels. The research problem is studied through five research articles, which offer micro-level case studies to macro-level phenomenon. Each of the articles focus on different aspects related to ageing and change, and utilise various datasets. The framework of this study leans on the studies of socio-technical systems and multi-level perspective on transitions mainly developed by Frank Geels. Essential factors in transition from one socio-technological regime to another are the co-evolutionary processes between landscape changes, regime level and experimental niches. Landscape level changes, like the ageing of the population, destabilise the regime in the forms of coming pressures. This destabilization offers windows for opportunity to niche-innovations outside or at fringe of the regime, which, through their breakthrough, accelerate the transition process. However, the change is not easy because of various kinds of lock-ins and inertia, which tend to maintain the stability of the regime. In this dissertation, a constructionist approach of society is applied leaning mainly to the ideas of Anthony Giddens’ theory of structuration, with the dual nature of structures. The change is taking place in the interplay between actors and structures: structures shape people’s practices, but at the same time these practices constitute and reproduce social systems. Technology and other material aspects, as part of socio-technical systems, and the use of them, also take part in the structuration process. The findings of the study point out that co-evolutionary and co-effective relationships between economic, cultural, technological and institutional fields, as well as relationships between landscape changes, changes in the local and regime-level practices and rule systems, are a very complex and multi-level dynamic socio-technical phenomenon. At the landscape level of ageing, which creates the pressures and triggers to the regime change, there are three remarkable megatrends: demographic change, changes in the global economy and the development of technologies. These exert pressures to the socio-technical regime, which as a rule system is experiencing changes in the form of new markets and consumer habits, new ways of perceiving ageing, new models of organising the health care and other services and as new ways of considering innovation and innovativeness. There are also inner dynamics in the relationships between these aspects within the regime. These are interrelated and coconstructed: the prevailing perceptions of ageing and innovation, for instance, reflect the ageing policies, innovation policies, societal structures, organising models, technology and scientific discussion, and vice versa. Technology is part of the inner dynamics of the sociotechnological regime. Physical properties of the artefacts set limitations and opportunities with regard to their functions and uses. The use of and discussion about technology, contributes producing and reproducing the perceptions of old age. For societal transition, micro-level changes are also needed, in form of niche-innovations, for instance new services, organisational models or new technologies, Regimes, as stabilitystriven systems, tend to generate incremental innovations, but radically new innovations are generated in experimental niches protected from ‘normal’ market selection. The windows of opportunity for radical novelties may be opened if the circumstances are favourable for instance by tensions in the socio-technical regime affected by landscape level changes. This dissertation indicates that a change is taking place, firstly, in the dynamic interactionbetween levels, as a result of purposive action and governance to some extent. Breaking the inertia and using the window of opportunity for change and innovation offered by dynamics between levels, presupposes the actors’ special capabilities and actions such as dynamic capabilities and distance management. Secondly, the change is taking place the socio-technological negotiations inside the regime: interaction between technological and social, which is embodied in the use of technology. The use of technology includes small-level contextual scripts that also participate in forming broader societal scripts (for instance defining old age at the society level), which in their turn affect the formation of policies for innovation and ageing. Thirdly, the change is taking place by the means of active formation of the multi-actor innovation networks, where the role of distance management is crucial to facilitate the communication between actors coming from different backgrounds as well as to help the niches born outside the regime to utilise the window of opportunity offered by regime destabilisation. This dissertation has both theoretical and practical contributions. This study participates in the discussion of action-oriented view on transition by opening up of the socio-technological, coevolutionary processes of the multi-faceted phenomenon of ageing, which has lacked systematic analyses. The focus of this study, however, is not on the large-scale coordination and governance, but rather on opening up the incremental elements and structuration processes, which contribute to the transition little by little, and which can be affected to. This increases the practical importance of this dissertation, by highlighting the importance of very tiny, everyday elements in the change processes in the long run.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Sementti on yksi eniten maailmassa käytetty rakennusmateriaali ja Suomessa sementin valmistuksesta vastaa Finnsementti Oy kahden tehtaan voimin. Lappeenrannan tehtaalle investoitiin uusi uunilinja vuonna 2007, joka on aikansa kehittyneintä tekniikkaa. Järjes-telmän esilämmitysvaiheen laitteissa, erityisesti kalsinaattorissa, on esiintynyt luvattoman paljon plastisoitumista ja murtumia. Tässä työssä tutkittiin lämpötilan ja sen vaihtelun vaikutusta järjestelmässä syntyneisiin siirtymiin ja murtumiin. Työn alussa luotiin katsaus erilaisiin murtumisilmiöihin ja niiden syntyyn. Vuorauksessa käytettyihin tiilien käyttäytymistä tutkittiin myös, koska ne ovat olennainen osa esilämmi-tysjärjestelmää. Työn kokeellisessa osuudessa aluksi määriteltiin järjestelmässä käytetylle teräkselle lujuusominaisuudet tutkimalla mikrorakennetta sekä suorittamalla veto- että kovuuskokeet materiaalille. Toisessa osiossa mitattiin järjestelmän alasajon aikana tapah-tuneet siirtymät. Laskennallisessa osuudessa tutkittiin väsymismurtuman mahdollisuutta sekä määritettiin kuoressa esiintyvän särön vaikutusta puhkeamis- ja murtumiskuormituk-seen. FEM- analyysissä tarkasteltiin lämpötilan vaikutusta siirtymien suuruuksiin ja pyrittiin löytämään perusteluita, miksi rakenne on todellisuudessa siirtynyt eri suuntiin kuin alun perin oli tarkoitettu. Lisäksi analysoitiin FEM- mallit tiilihyllystä ja kalsinaattorin kuoren tukikehästä, joista tutkittiin lämpökuorman aiheuttamia jännityksiä. Materiaalin osalta selvisi, että kyseessä oli hyvin yleinen rakenneteräs S235 tai sitä vas-taava teräslaatu. Teräs ei ominaisuuksiltaan sovellu kuumiin olosuhteisiin, jonka vuoksi järjestelmässä käytettävän eristevuorauksen kunto on erityisen tärkeä rakenteen käyttöiän kannalta. Vuorauksen kunnosta riippuu, kuinka suuren lämpökuorman teräskuori saa. Väsymismurtuman mahdollisuus jäi minimaalisen pieneksi lämpötilan muutoksen vaiku-tuksesta. Analysoinnin tulosten perusteella voitiin todeta, että lämpötilan hitaasti mutta kohtalaisen suurella vaihteluvälillä sekä tiilien turpoamisen vaikutuksella on erittäin suuri merkitys järjestelmässä esiintyviin murtumiin.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Novel biomaterials are needed to fill the demand of tailored bone substitutes required by an ever‐expanding array of surgical procedures and techniques. Wood, a natural fiber composite, modified with heat treatment to alter its composition, may provide a novel approach to the further development of hierarchically structured biomaterials. The suitability of wood as a model biomaterial as well as the effects of heat treatment on the osteoconductivity of wood was studied by placing untreated and heat‐treated (at 220 C , 200 degrees and 140 degrees for 2 h) birch implants (size 4 x 7mm) into drill cavities in the distal femur of rabbits. The follow‐up period was 4, 8 and 20 weeks in all in vivo experiments. The flexural properties of wood as well as dimensional changes and hydroxyl apatite formation on the surface of wood (untreated, 140 degrees C and 200 degrees C heat‐treated wood) were tested using 3‐point bending and compression tests and immersion in simulated body fluid. The effect of premeasurement grinding and the effect of heat treatment on the surface roughness and contour of wood were tested with contact stylus and non‐contact profilometry. The effects of heat treatment of wood on its interactions with biological fluids was assessed using two different test media and real human blood in liquid penetration tests. The results of the in vivo experiments showed implanted wood to be well tolerated, with no implants rejected due to foreign body reactions. Heat treatment had significant effects on the biocompatibility of wood, allowing host bone to grow into tight contact with the implant, with occasional bone ingrowth into the channels of the wood implant. The results of the liquid immersion experiments showed hydroxyl apatite formation only in the most extensively heat‐treated wood specimens, which supported the results of the in vivo experiments. Parallel conclusions could be drawn based on the results of the liquid penetration test where human blood had the most favorable interaction with the most extensively heat‐treated wood of the compared materials (untreated, 140 degrees C and 200 degrees C heat‐treated wood). The increasing biocompatibility was inferred to result mainly from changes in the chemical composition of wood induced by the heat treatment, namely the altered arrangement and concentrations of functional chemical groups. However, the influence of microscopic changes in the cell walls, surface roughness and contour cannot be totally excluded. The heat treatment was hypothesized to produce a functional change in the liquid distribution within wood, which could have biological relevance. It was concluded that the highly evolved hierarchical anatomy of wood could yield information for the future development of bulk bone substitutes according to the ideology of bioinspiration. Furthermore, the results of the biomechanical tests established that heat treatment alters various biologically relevant mechanical properties of wood, thus expanding the possibilities of wood as a model material, which could include e.g. scaffold applications, bulk bone applications and serving as a tool for both mechanical testing and for further development of synthetic fiber reinforced composites.