Global ETD Search

131	Unapređenje kvaliteta alata za livenje pod pritiskom primenom tehnologija inženjerstva površina / Application of surface engineering technologies for improvement of diecasting tools quality Terek Pal 21 September 2016 (has links) <p>Proučavane su koroziona postojanost i tendencija lepljenja različitih<br />materijala u kontaktu sa tečnom Al–Si–Cu legurom. Ispitivanjem su<br />obuhvaćeni čelik za rad na toplo, plazma nitrirani čelik i dupleks<br />slojevi sa CrN, TiAlN, TiAlSiN i CrAlN prevlakama, različitog nivoa<br />površinske hrapavosti. Za ispitivanja pomenutih fenomena<br />primenjena je metoda izvlačenja, koja je unapređena kako bi se povećale<br />njena tačnost i verodostojnost simulacije procesa livenja. Korozioni<br />efekti su pojačani tako što su uzorci osim kratkog kontakta sa odlivkom<br />zadržavani i u dužim periodima u kontaktu sa tečnom legurom (5 i 20<br />min). Uprkos opštim stavovima, za ispitivane materijale je<br />ustanovljeno da su sile izvlačenja uzoraka iz Al–Si–Cu odlivaka<br />nezavisne od njihovog hemijskog sastava. Uticaj hrapavosti je izražen<br />kod uzoraka sa prevlakama kod kojih pri smanjenju hrapavosti dolazi do<br />povećanja sile izvlačenja. Sve ispitane prevlake su sklone mehaničkom<br />lepljenju Al–Si–Cu legure za svoje površine, ali sa aspekta korozije u<br />tečnom metalu značajno prevazilaze performanse čelika i plazma<br />nitriranog sloja. Duži kontakt livene legure sa površinama prevlaka<br />uzrokovao je niže vrednosti sila izvlačenja, što je posledica<br />oksidacije površina prevlaka. Ustanovljeno je da su ispitivane<br />prevlake inertne ka tečnoj leguri aluminijuma. Međutim, dolazi do<br />oksidacije i korozije materijala podloge kroz greške rasta koje su<br />prisutne u prevlakama. Stečena znanja o identifikovanim<br />mehanizmima habanja i propadanja zaštitnih slojeva prevlaka<br />poslužiće daljem razvoju dupleks slojeva namenjenih za zaštitu alata<br />za livenje pod pritiskom.</p> / <p>Corrosion resistance and soldering tendency of different materials in molten<br />Al–Si–Cu alloy were studied. Hot-working tool steel, plasma nitrided steel and<br />duplex layers with CrN, TiAlN, TiAlSiN and CrAlN top coatings, which were<br />produced to various degree of surface roughness, were covered by the study.<br />An ejection test was employed for investigation of the concerned phenomena.<br />The ejection test was improved in order to increase its accuracy and the<br />reliability of process simulation. Samples were examined in both short and<br />extended periods of contact (5 and 20 min) with liquid casting. Casting<br />solidification was extended in order to intensify the corrosion effects. Contrary<br />to common findings, it was found that the ejection force of the investigated<br />materials does not depend on their chemical composition. For the coated<br />samples, a pronounced dependence of the ejection force on the surface<br />roughness was found. The ejection force increases with decrease in surface<br />roughness. All investigated coatings are prone to mechanical soldering by Al–<br />Si–Cu alloy. Still, their corrosion resistance substantially exceeds the corrosion<br />resistance of steel and plasma nitrided layer. Longer exposure of coated<br />samples to cast alloy induced lower ejection forces, which is a consequence<br />of coatings oxidation. It was found that the investigated coatings are inert to<br />liquid aluminium. However, the underlying material undergoes oxidation and<br />corrosion through coating growth defects. The findings concerning the wear<br />mechanisms of protective layers support further development of duplex layers<br />intended for die casting tools protection.</p>
132	A pentecostal response to the challenges of HIV/AIDS in Tumahole Skhosana, Thabang Johannes 11 1900 (has links) This dissertation is a challenge to the Pentecostal churches, particularly, the Apostolic Faith Mission Church in Tumahole, to take an action in meeting the challenges posed by HIV/AIDS. This disease, HIV/AIDS, is the latest enemy to human life that the nations are faced with. In the newspapers like Sowetan, there is an article almost daily about HIV and AIDS. In this dissertation, I have tried to show shocking figures of how this disease is spreading in Africa. The seriousness of the disease, unlike other diseases, is its in curability. The secular organisations are far ahead of the churches in as far as the relevant programmes on combating HIV/AIDS are concerned. Despite these massive programmes, the disease is spreading like the wild fire. Deducing from this background, it is no longer the question of whether the Pentecostal churches have any role to play, but what specific role should the church play in this challenge. In this challenging times, many people look at the church as one of the most important institute that would play a positive role in bringing hope to the hopeless. / Christian Spirituality, Church History and Missiology / M. Th. (Missiology (Urban Ministry)) AIDS: Acquired Immunedeficiency Syndrome ARC: AIDS Related Complex (sicknesses) AZT: Zidovudine Drug HIV: Human Immunedeficiency Virus TB: Tuberculosis TLC: Transitional Local Council PCP: Pneumocystis Carinii Pneumonia WHO: World Health Organisation 261.8321969792 Apostolic Faith Mission of South Africa AIDS (Disease) -- Religious aspects Church work with the sick Tumahole (Parys, South Africa)
133	A pentecostal response to the challenges of HIV/AIDS in Tumahole Skhosana, Thabang Johannes 11 1900 (has links) This dissertation is a challenge to the Pentecostal churches, particularly, the Apostolic Faith Mission Church in Tumahole, to take an action in meeting the challenges posed by HIV/AIDS. This disease, HIV/AIDS, is the latest enemy to human life that the nations are faced with. In the newspapers like Sowetan, there is an article almost daily about HIV and AIDS. In this dissertation, I have tried to show shocking figures of how this disease is spreading in Africa. The seriousness of the disease, unlike other diseases, is its in curability. The secular organisations are far ahead of the churches in as far as the relevant programmes on combating HIV/AIDS are concerned. Despite these massive programmes, the disease is spreading like the wild fire. Deducing from this background, it is no longer the question of whether the Pentecostal churches have any role to play, but what specific role should the church play in this challenge. In this challenging times, many people look at the church as one of the most important institute that would play a positive role in bringing hope to the hopeless. / Christian Spirituality, Church History and Missiology / M. Th. (Missiology (Urban Ministry)) AIDS: Acquired Immunedeficiency Syndrome ARC: AIDS Related Complex (sicknesses) AZT: Zidovudine Drug HIV: Human Immunedeficiency Virus TB: Tuberculosis TLC: Transitional Local Council PCP: Pneumocystis Carinii Pneumonia WHO: World Health Organisation 261.8321969792 Apostolic Faith Mission of South Africa AIDS (Disease) -- Religious aspects Church work with the sick Tumahole (Parys, South Africa)
134	GRUPPARBETE INOM HEM- OCH KONSUMENTKUNSKAP : En kvalitativ intervjustudie utifrån lärares perspektiv / GROUP WORK IN HOME AND CONSUMER STUDIES : A qualitative interview studyfrom teachers’ perspective Erlandsson Tordsjänta, Marie, Boode Nylander, Madeleine January 2022 (has links) SAMMANFATTNING Bakgrund Elevers grupparbeten utgör en betydande del av HKK-undervisningen. Tidigare forskning kring elevers grupparbeten i allmänhet är omfattande, men forskning gällande elevers grupparbeten inom HKK är ytterst begränsad. Som utpräglat processämne är det av största vikt att eleverna ges möjlighet att träna på praktiska moment inom hem- och konsumentkunskap (HKK), för att eleverna ska kunna utveckla kunskap i handling vilket sedermera ska bedömas av undervisande lärare. Syfte Syftet med studien var att utforska lärares uppfattningar, upplevelser och erfarenheter av grupparbete i HKK. Metod Kvalitativa intervjuer genomfördes med tio HKK-lärare runtom i Sverige. Intervjuerna analyserades med stöd av kvalitativ innehållsanalys. Resultat Det mest framträdande resultatet i studien var att arbetsformen grupparbete var dominerande i såväl praktiskt som teoretiskt arbete inom HKK. Ramfaktorer påverkade, styrde och begränsade undervisningen. Samarbete, kamratlärande, trygghet och praktisk träning var främsta syften med grupparbeten inom HKK. Det sociala klimatet, elevernaskunskapsnivå och särskilda behov var de faktorer som främst togs i beaktning vid sammansättning av elevgrupper. Lärarnas arbete kring elevgruppernas varaktighet skilde sig åt. Observationer var den vanligaste bedömningsformen när elever arbetade i grupp. Bedömning av elever som arbetade i grupp upplevdes vara svårt och utmanande bland lärarna i studien. Slutsats Grupparbete som undervisningsmetod framstår som rådande kutym inom ämnet. Studien påvisade brister med denna undervisningsmetod, främst utifrån bedömningsaspekten. Med mer noggrant uttänkta strategier för varför, hur och när det vore lämpligt att använda grupparbete som undervisningsmetod anser vi att HKK-läraren har möjlighet att höja kvaliteten på såväl undervisning som bedömning. / ABSTRACT Background Students' group work constitutes a significant part of the teaching in Home and Consumer Studies (HCS). Previous research on students 'group work in general is extensive, but research on students' group work within HCS is extremely limited. As a distinct process subject, it is of the utmost importance that students are given the opportunity to practice practical elements in HCS, so that students can develop ”knowledge in action”, which will be assessed by the teacher. Objective The aim of the study was to explore the teachers’ perceptions and experiences regarding group work in HCS. Method Qualitative interviews were conducted with ten teachers in HCS within Sweden. The interviews were analyzed on the basis of content analysis. Results The most prominent result in the study was that group work was dominant in both practical and theoretical work within HCS. Framework factors influenced, controlled and limited teaching. Cooperation, peer learning, safety and practical training were the main purposes of group work within HCS. The social climate, the students' level of knowledge and special needs were the factors that were mainly taken into account when composing student groups. The teachers' work on the duration of the student groups differed. Observations were the most common form of assessment when students worked in groups. Assessment of students who worked in groups was perceived as difficult and challenging among the teachers in the study. Conclusion Group work as a teaching method appears to be the prevailing custom within the subject. The study demonstrated shortcomings with this teaching method, mainly based on the assessment aspect. With more carefully thought out strategies for why, how and when it would be appropriate to use group work as a teaching method, we believe that the HCS teacher has the opportunity to raise the quality of both teaching and assessment. knowledge in action teachers' perceptions qualitative method framework factors cooperation peer learning security and practical training Grupparbete i hem- och konsumentkunskap kunskap i handling lärares uppfattningar kvalitativ metod ramfaktorer samarbete kamratlärande trygghet och praktisk träning Didactics Didaktik
135	Correlación entre conocimientos sobre consecuencias de la obesidad y grado de actividad física en universitarios Ocampo Mascaró, Javier, Silva Salazar, Vera Jimena, da Costa Bullón, Abilio 03 February 2015 (has links) Introducción. El objetivo del presente estudio es determinar si existe correlación entre los conocimientos sobre las consecuencias de la obesidad y el grado de actividad física de las personas. Métodos. Se realizó un estudio transversal analítico durante los años 2013 y 2014. Participaron 215 alumnos de pregrado seleccionados por conveniencia no relacionados a carreras del campo de la salud en una universidad de Lima, Perú. Se evaluó el grado de actividad física utilizando el International Physical Activity Questionnaire (IPAQ) y el nivel de conocimientos sobre consecuencias de la obesidad utilizando la escala Obesity Risk Knowledge-10 (ORK-10). También, se consignó las fuentes de información de donde obtuvieron el conocimiento para responder dicho cuestionario. Resultados. La mediana de edad fue 20 (rango intercuartílico=4) y 63% eran mujeres. De acuerdo al IPAQ, 53,9% realizaban actividad física alta, 35,4%, moderada y 10,7%, leve. Se encontró una correlación muy baja (rs=0,06) entre el puntaje del ORK-10 y la cantidad de equivalentes metabólicos/minuto consumidos por semana, pero no era significativa (p=0,38). Las personas informadas por medios de comunicación y por personal de salud obtuvieron mayores puntajes en el ORK- 10 que quienes se informaron por otras vías (p<0,05). Conclusiones. La correlación entre los conocimientos sobre consecuencias de la obesidad y el grado de actividad física es muy baja. Es necesario utilizar enfoques multidisciplinarios que incluyan todos los determinantes de la realización de actividad física para poder lograr cambios en la conducta de la población. Actividad física Obesidad Conocimientos Actitudes y prácticas en salud Sobrepeso Motivación Physical Activity Obesity Health Knowledge , Attitudes and Practice Overweight Motivation
136	The Rtg1 and Rtg3 proteins are novel transcription factors regulated by the yeast hog1 mapk upon osmotic stress Noriega Esteban, Núria 27 February 2009 (has links) La adaptación de la levadura Saccharomyces cerevisiae a condiciones de alta osmolaridad está mediada por la vía de HOG ((high-osmolarity glycerol). La activación de esta vía induce una serie de respuestas que van a permitir la supervivencia celular en respuesta a estrés. La regulación génica constituye una respuesta clave para dicha supervivencia. Se han descrito cinco factores de transcripción regulados por Hog1 en respuesta a estrés osmótico. Sin embargo, éstos no pueden explicar la totalidad de los genes regulados por la MAPK Hog1. En el presente trabajo describimos cómo el complejo transcripcional formado por las proteínas Rtg1 y Rtg3 regula, a través de la quinasa Hog1, la expresión de un conjunto específico de genes. Hog1 fosforila Rtg1 y Rtg3, aunque ninguna de estas fosforilaciones son esenciales para regulación transcripcional en respuesta a estrés. Este trabajo también muestra cómo la deleción de proteínas RTG provoca osmosensibilidad celular, lo que indica que la integridad de la vía de RTG es esencial para la supervivencia celular frente a un estrés osmótico. / In Saccharomyces cerevisiae the adaptation to high osmolarity is mediated by the HOG (high-osmolarity glycerol) pathway, which elicits different cellular responses required for cell survival upon osmostress. Regulation of gene expression is a major adaptative response required for cell survival in response to osmotic stress. At least five transcription factors have been reported to be controlled by the Hog1 MAPK. However, they cannot account for the regulation of all of the genes under the control of the Hog1 MAPK. Here we show that the Rtg1/3 transcriptional complex regulates the expression of specific genes upon osmostress in a Hog1-dependent manner. Hog1 phosphorylates both Rtg1 and Rtg3 proteins. However, none of these phosphorylations are essential for the transcriptional regulation upon osmostress. Here we also show that the deletion of RTG proteins leads to osmosensitivity at high osmolarity, suggesting that the RTG-pathway integrity is essential for cell survival upon stress. OD: optical density NAD+: nicotinamide adenine dinucleotide MAPK: mitogen activated protein kinase HOG: high osmolarity glycerol ERC: extrachromosomal rDNA circles CDK: cyclin dependent kinase DNA: desoxirribobucleic acid ATP: adenosine triphosphate AMP: adenosine monophosphate TOR: Diana de la rapamicina STRE element de resposta a l'estrés ROS: especies reactives de l'oygen rDNA: DNA risbosomal OD: densitat òptica NAD+: nicotinàmida adenina dinucleòtid HOG: osmolaritat elevada de glicerol rDNA: risbosomal DNA ERC: cercle d'rDNA extracromosòmic DNA: àcid desoxirriblonucleic CDK: Kinassa dependent de ciclines ATP: trifosfat d'adenosina AMP: monofosfat d'adenosina ROS: reactive oxygen species SAPK: stress activated protein kinase STRE: stress response element TOR: target of rapamycin 575 58
137	From the "rising tide" to solidarity: disrupting dominant crisis discourses in dementia social policy in neoliberal times MacLeod, Suzanne 26 March 2014 (has links) As a social worker practising in long-term residential care for people living with dementia, I am alarmed by discourses in the media and health policy that construct persons living with dementia and their health care needs as a threatening “rising tide” or crisis. I am particularly concerned about the material effects such dominant discourses, and the values they uphold, might have on the collective provision of care and support for our elderly citizens in the present neoliberal economic and political context of health care. To better understand how dominant discourses about dementia work at this time when Canada’s population is aging and the number of persons living with dementia is anticipated to increase, I have rooted my thesis in poststructural methodology. My research method is a discourse analysis, which draws on Foucault’s archaeological and genealogical concepts, to examine two contemporary health policy documents related to dementia care – one national and one provincial. I also incorporate some poetic representation – or found poetry – to write up my findings. While deconstructing and disrupting taken for granted dominant crisis discourses on dementia in health policy, my research also makes space for alternative constructions to support discursive and health policy possibilities in solidarity with persons living with dementia so that they may thrive. / Graduate / 0452 / 0680 / 0351 / macsuz@shaw.ca social determinants of health social exclusion crisis discourse Alzheimer's Alzheimer Society of Canada Suzanne MacLeod Susan Strega Donna Jeffery poststructural poststructuralism admission to long-term care funding for long-term care acute care aging demographic BC Psychogeriatric Association biomedical British Columbia Canada Health Act collective social responsibility competition corporate profit corporatization deresponsibilization elder friendly elderly citizens family caregivers Foucault found poetry genealogy of power knowledge incompetent Ministry of Health moral economics pharmaceutical bed blocker stigmatized tsunami absent-person action plan aging population alternative discourse apocalyptic demography appropriate archaeology archaeology of knowledge archaeological British Columbia burden Canada caregiver charity charitable collective collective car community community care condition of possibility conditions of possibility corporate counter-discourse dementia dementia care dementia policy dementia social policy dependent depoliticize discourse discourse analysis disruptive discourse economic burden economics economy elder emergency epidemic exclusion fear-monger Foucauldian found poem genealogy genealogical health authority health care health care staff health care system health policy document healthy lifestyle home and community care homogenization homogenize hospital imaginaries imaginary incapable individual responsibility individualism knowledge long-term care material effect materiality of discourse media moral panic national strategy neoliberal neoliberalism neoliberal rationality not prepared object objectification other person-centered people living with dementia person living with dementia persons living with dementia person with dementia poem poetic representation poetry policy policies political politics power power knowledge power relations private privatize privatization productivity of dominant discourse public health care residential care resistance responsibility responsibilization rising tide safety net shift costs to caregivers responsibility social policy imaginary social well-being social work social worker solidarity specialized stakeholder state stigma subject matter expert taxpayer threat unprepared unproductive voluntary volunteer wait time wave social policy
138	From the "rising tide" to solidarity: disrupting dominant crisis discourses in dementia social policy in neoliberal times MacLeod, Suzanne 26 March 2014 (has links) As a social worker practising in long-term residential care for people living with dementia, I am alarmed by discourses in the media and health policy that construct persons living with dementia and their health care needs as a threatening “rising tide” or crisis. I am particularly concerned about the material effects such dominant discourses, and the values they uphold, might have on the collective provision of care and support for our elderly citizens in the present neoliberal economic and political context of health care. To better understand how dominant discourses about dementia work at this time when Canada’s population is aging and the number of persons living with dementia is anticipated to increase, I have rooted my thesis in poststructural methodology. My research method is a discourse analysis, which draws on Foucault’s archaeological and genealogical concepts, to examine two contemporary health policy documents related to dementia care – one national and one provincial. I also incorporate some poetic representation – or found poetry – to write up my findings. While deconstructing and disrupting taken for granted dominant crisis discourses on dementia in health policy, my research also makes space for alternative constructions to support discursive and health policy possibilities in solidarity with persons living with dementia so that they may thrive. / Graduate / 0452 / 0680 / 0351 / macsuz@shaw.ca social determinants of health social exclusion crisis discourse Alzheimer's Alzheimer Society of Canada Suzanne MacLeod Susan Strega Donna Jeffery poststructural poststructuralism admission to long-term care funding for long-term care acute care aging demographic BC Psychogeriatric Association biomedical British Columbia Canada Health Act collective social responsibility competition corporate profit corporatization deresponsibilization elder friendly elderly citizens family caregivers Foucault found poetry genealogy of power knowledge incompetent Ministry of Health moral economics pharmaceutical bed blocker stigmatized tsunami absent-person action plan aging population alternative discourse apocalyptic demography appropriate archaeology archaeology of knowledge archaeological British Columbia burden Canada caregiver charity charitable collective collective car community community care condition of possibility conditions of possibility corporate counter-discourse dementia dementia care dementia policy dementia social policy dependent depoliticize discourse discourse analysis disruptive discourse economic burden economics economy elder emergency epidemic exclusion fear-monger Foucauldian found poem genealogy genealogical health authority health care health care staff health care system health policy document healthy lifestyle home and community care homogenization homogenize hospital imaginaries imaginary incapable individual responsibility individualism knowledge long-term care material effect materiality of discourse media moral panic national strategy neoliberal neoliberalism neoliberal rationality not prepared object objectification other person-centered people living with dementia person living with dementia persons living with dementia person with dementia poem poetic representation poetry policy policies political politics power power knowledge power relations private privatize privatization productivity of dominant discourse public health care residential care resistance responsibility responsibilization rising tide safety net shift costs to caregivers responsibility social policy imaginary social well-being social work social worker solidarity specialized stakeholder state stigma subject matter expert taxpayer threat unprepared unproductive voluntary volunteer wait time wave social policy
139	Hårdgörning av Asp / Densification of Aspen Wood Johansson, Martin January 2008 (has links) Hårdgörning av trä syftar till att göra materialet hårdare. Detta går att åstadkomma genom komprimering, det komprimerade materialet tenderar dock att återgå mot sin ursprungsform då materialet utsätts för fukt om ingen låsning sker. Låsningen kan ske mekaniskt i en treskiktskonstruktion som motverkar träets fuktrörelser. Dessa skivor har dock visat sig vara instabila och tidigare försök har uppvisat deformationer i form av kupning. Denna undersökning syftar till att utreda förutsättningarna för att använda komprimerad asp samt att ta fram underlag för framtagning av en kommersiell produkt. Praktiska tester har genomförts för att studera hårdhet, återfjädring och densitet hos det komprimerade virket. Vidare har treskiktsskivor tagits fram för att testa om det går att få en stabil konstruktion genom att variera tjockleken på spärrskiktet. Även skillnader i acklimatiseringstid och fuktkvotens inverkan för virkets återfjädring har studerats. Resultaten visar på att aspens hårdhet efter komprimering blir i samma nivå som bok och ask, en låg fuktkkvot vid komprimering av materialet ger en låg återfjädring, komprimerat material har en längre acklimatiseringstid till jämviktsfuktkvot och materialet går att låsa tvärs fiberriktningen i en treskiktskonstruktion. / To make wood harder it can be densified. This can be achieved by compression, the compressed material tends to return to the original shape when it is exposed to moisture fluxations and if no form of fixation occurs. The fixation can be done mechanically in a three-layer panel construction which reduce movements in the timber. These panels have been found to be unstable and previous attempts have shown deformations in form of cupping. This study aims to evaluate the conditions for using compressed aspen wood, and to provide a basis for development of a commercial product. Practical tests have been conducted to study hardness, springback and density of the compressed wood. In addition, three-layer panels have been developed to test whether it is possible to have a stable construction by varying the thickness of the buttom layer. Differences in acclimatisation time and the moisture contents effect on the springback has aslo been studied. The results show that the hardness of aspen wood after compression is in equal levels with beech and ashes, a low moisture contet provides a low springback, compressed timber have a longer time for acclimatisation and it is possible to fixate the material in the direction across the grain in a three-layer panel construction. Hårdgjord asp asp Populus tremula treskiktsskivor radiell komprimering återfjädring hårdhet acklimatisering Wood fibre and forest products Träfiber- och virkeslära
140	Hårdgörning av Asp / Densification of Aspen Wood Johansson, Martin January 2008 (has links) <p>Hårdgörning av trä syftar till att göra materialet hårdare. Detta går att åstadkomma genom komprimering, det komprimerade materialet tenderar dock att återgå mot sin ursprungsform då materialet utsätts för fukt om ingen låsning sker. Låsningen kan ske mekaniskt i en treskiktskonstruktion som motverkar träets fuktrörelser. Dessa skivor har dock visat sig vara instabila och tidigare försök har uppvisat deformationer i form av kupning. Denna undersökning syftar till att utreda förutsättningarna för att använda komprimerad asp samt att ta fram underlag för framtagning av en kommersiell produkt.</p><p>Praktiska tester har genomförts för att studera hårdhet, återfjädring och densitet hos det komprimerade virket. Vidare har treskiktsskivor tagits fram för att testa om det går att få en stabil konstruktion genom att variera tjockleken på spärrskiktet. Även skillnader i acklimatiseringstid och fuktkvotens inverkan för virkets återfjädring har studerats.</p><p>Resultaten visar på att aspens hårdhet efter komprimering blir i samma nivå som bok och ask, en låg fuktkkvot vid komprimering av materialet ger en låg återfjädring, komprimerat material har en längre acklimatiseringstid till jämviktsfuktkvot och materialet går att låsa tvärs fiberriktningen i en treskiktskonstruktion.</p> / <p>To make wood harder it can be densified. This can be achieved by compression, the compressed material tends to return to the original shape when it is exposed to moisture fluxations and if no form of fixation occurs. The fixation can be done mechanically in a three-layer panel construction which reduce movements in the timber. These panels have been found to be unstable and previous attempts have shown deformations in form of cupping. This study aims to evaluate the conditions for using compressed aspen wood, and to provide a basis for development of a commercial product.</p><p>Practical tests have been conducted to study hardness, springback and density of the compressed wood. In addition, three-layer panels have been developed to test whether it is possible to have a stable construction by varying the thickness of the buttom layer. Differences in acclimatisation time and the moisture contents effect on the springback has aslo been studied.</p><p>The results show that the hardness of aspen wood after compression is in equal levels with beech and ashes, a low moisture contet provides a low springback, compressed timber have a longer time for acclimatisation and it is possible to fixate the material in the direction across the grain in a three-layer panel construction.</p> Hårdgjord asp asp Populus tremula treskiktsskivor radiell komprimering återfjädring hårdhet acklimatisering Wood fibre and forest products Träfiber- och virkeslära

Search results