Die Marktbedingungen in der Automobilindustrie sind durch kürzere Entwicklungszeiträume, eine zunehmende Anzahl an Komfortfunktionen und Fahrzeugderivaten sowie steigende Erwartungen an Qualität, Effizienz und Sicherheit geprägt. Die reale Erprobung ist ein kritischer Pfad im Entwicklungsprozess. Die vorliegende Arbeit beschreibt ein neues Prüfsystemkonzept für die Komponentenerprobung, welches diesen Anforderungen Rechnung trägt. Das Herzstück ist eine softwarebasierte Systemarchitektur zur Automatisierung von Prototypentests. Schwerpunkte sind die Flexibilität in der Praxisanwendung, die Ausweitung der Messdatenerfassung mit zweckmäßiger Verwaltung zur Bauteilüberwachung und Fehlerrekonstruktion sowie eine aufgabenorientierte Schnittstelle zur Integration von Robotern. Diese übernehmen die mechanische Betätigung von beweglichen Fahrzeugkomponenten. Anhand von zwei konkreten Beispielen, einem Prüfstand zur Absicherung von Fahrzeugtüren sowie einem Prüfstand für Steifigkeitsmessungen wird die Praxistauglichkeit nachgewiesen.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Title: Posterior chain muscle endurance and arm paddling peak power in amateur female surfers Objectives: Thesis is dedicated to female surfing, particularly paddling, as this is an undiscovered area of research. Very few studies have been carried out, which would focus on muscle activity in surfing. None of the studies focused on posterior chain or muscle activity of female surfers while paddling. Not only that the level of competitive surfing is increasing rapidly, as it will be part of Olympic Games in Tokyo in 2020, but the recreational surfers are also becoming more literate about surf science and willing to improve their surfing performance by dry land surf specific trainings. Surfing industry represents a worldwide business, where big companies offer sponsorship, which is reasonable motivation for young athletes (M. Mendez-Villanueva & Bishop, 2005). As the number of recreational and competitive female surfers is raising as well, the level of competitive female surfing is increasing (Booth, 2001) and professional female surfers are becoming equal in regards to getting the same amount of prize money in competitions, more research should be dedicated to female surfing. The aim of this thesis was to study association between posterior chain endurance and other variables such as frequency of...

Submitted by Sara Ribeiro (sara.ribeiro@ucb.br) on 2018-08-08T17:35:32Z No. of bitstreams: 1 SebastianDelRossoDissertacao2018.pdf: 1818866 bytes, checksum: 3274a8646557f8e415e970e9bbe7a015 (MD5) / Approved for entry into archive by Sara Ribeiro (sara.ribeiro@ucb.br) on 2018-08-08T17:35:47Z (GMT) No. of bitstreams: 1 SebastianDelRossoDissertacao2018.pdf: 1818866 bytes, checksum: 3274a8646557f8e415e970e9bbe7a015 (MD5) / Made available in DSpace on 2018-08-08T17:35:47Z (GMT). No. of bitstreams: 1 SebastianDelRossoDissertacao2018.pdf: 1818866 bytes, checksum: 3274a8646557f8e415e970e9bbe7a015 (MD5) Previous issue date: 2018-02-28 / The main goal of the present study was to identify the main determinants influencing and thus explaining pacing and performance during self-paced 10 km running time trial and develop prediction equations including metabolic/respiratory and neuromuscular variables. Twenty-seven well-trained runners (age = 26,4 ± 6,5 years, training experience = 7,4 ± 5,9 years, training volume = 89,1 ± 39,1 km·week-1, VO2max = 62,3 ± 4,5 mL·kg-1·min-1) completed three testing sessions: During the first session, body composition and mechanical variables (concentric peak velocity, PV; time to peak velocity, TPV; peak force, PF; and peak power, PP) in the half-squat (AG) and loaded squat jump (SSC) were measured. The second testing session was dedicated to assessing metabolic variables [VO2max, ventilatory thresholds (VT1 and VT2), cost of running (CR) and maximal speed (SMAX)] and vertical jump (CMJ) potentiation; while during the third session a 10 km self-paced time trial was carried out. Also, before and after (0, 3, 6, and 9 min) the 10 km, athletes completed 2 CMJ for measuring mechanical variables [eccentric displacement (DE), mean eccentric and concentric velocity (VME, VMC), eccentric and concentric peak velocity (PVE, PVC)]. Pacing was defined as the time (T10km) or speed (S10km) every 1000 m, and analysis of those factors influencing the 10 km performance was carried by means of hierarchic multiple regression, whit the inclusion of all available variables. In addition, regression analyses were performed to develop prediction equation for T10km. Cluster analyses were carried out to evaluate the effects of performance levels [high performance group, GAD; low performance group (GBD)] and jumping potentiation (potentiation group, GP; non-potentiation group, GNP). For the whole sample, the final model including SMAX, CR, o a AGVP, Δ3-Pre CMJPVE (m·s-1), HRmax (bpm) and SSCPF (N) was statistically significant; r2 = 0,91, F(6-26) = 35,64, P < 0,001, EES = 0,76, r2ADJUSTED = 0,89; while the prediction model included the following variables: SMAX, CR and AGVP [r2 = 0,75; F(3-26) = 22,52; P < 0,001; EES = 1,23]. For the performance groups, there were significant main simple effects for time [F(2-52) = 12,20, P<0,001), η2 = 0,32] and group [F(1-25) = 49,91; P<0,001, η2 = 0,66] and also differences in the explaining variables for T10km: GAD [SMAX; SSCPF, HRMEAN, CV10km e Post-0min CMJPVE, F(5-9) = 266,06; P <0,001; SSE = 0,09 min; r2ADJUSTED = 0,99]; GBD [VT2-%VO2max, Δ6-Pre CMJEPV, CR; F(4-18) = 33,16; P <0,001, EES = 0,045 min; r2ADJUSTED = 0,88]. Furthermore, different prediction equations were found for each group: GAD – [T10km (min) = 68,65 – (1,084 × SMAX) – (0,008 × SSCPF) + (0,083 × AGCARGA); r2 = 0,98]; GBD - T10km (min) = 44,75 – (1,05× SMAX) + (0,17×VT2-%VO2max) + (1,89 × CMJVME) – (0,061 × Age); r2 = 0,89]. For jump potentiation groups there were significant differences only in the last 400 m and RPE (GNP = 8,36 ± 1,6 vs. GP = 6,8 ± 1,7; P = 0,03). Also, jump potentiation correlated with the final 400 m time in the whole sample (r = -0.42; P = 0,031) and with RPE for the GAD group (r = -0,75; P = 0,032). In conclusion, the results of the present study suggest that mechanical factors are significant for endurance runners given that explain part of the variance in the T10km while allowed for performance prediction. Moreover, performance level appears to be related to neuromuscular differences influencing pacing whereas jump potentiation likely affects effort perception. / O objetivo do presente estudo foi analisar os diversos fatores que podem influenciar e por tanto explicar o desempenho em uma prova de corrida de 10 km assim como também em subsegmentos dos 10 km, e predizer desempenho a partir de variáveis metabólicas/respiratórias e neuromusculares. Para tal fim, 27 corredores bem treinados (idade = 26,4 ± 6,5 anos, experiência de treinamento = 7,4 ± 5,9 anos, volume de treinamento = 89,1 ± 39,1 km·semana-1, VO2max = 62,3 ± 4,5 mL·kg-1·min-1) completaram três sessões de avaliação: A primeira sessão foi dedicada à determinação das variáveis mecânicas (pico de velocidade concêntrica, PV; tempo até o pico de velocidade, TPV; pico de força, PF e pico de potência, PP) nos exercícios de médio agachamento (AG) e salto com sobrecarga (SSC) e das variáveis associadas à composição corporal; durante a segunda sessão se avaliaram variáveis metabólicas [VO2max, limiares ventilatórios (VT1, primer limiar ventilatório, VT2, segundo limiar ventilatório), custo energético da corrida (CR) e velocidade máxima (SMAX)] conjuntamente com a potencialização no salto vertical (CMJ); e durante a terceira sessão se registrou o desempenho em uma prova simulada de 10 km (T10km) com monitoramento continuo da velocidade (GPS) e da frequência cardíaca (FC). Antes e depois (0, 3, 6 e 9 min) dos 10 km os atletas completaram 2 saltos verticais (CMJ) para à avaliação das variáveis mecânicas associadas ao salto [deslocamento excêntrico (DE), velocidade média excêntrica e concêntrica (VME, VMC), pico de velocidade excêntrica e concêntrica (PVE, PVC)]. O ritmo de corrida foi definido como o tempo ou velocidade a cada 1000 m, e para as análises dos fatores implicados na variância do desempenho em 10 km foi realizada uma análise de regressão múltipla hierárquica utilizando todas as variáveis disponíveis. Além disso, análises de regressão foram completadas para determinar equações de predição do T10km com variáveis independentes das registradas durante a prova. Entanto que analises por conglomerados foram utilizados para analisar os efeitos do nível de desempenho (grupo de alto desempenho, GAD; grupo de baixo desempenho, GBD) e da potencialização do salto vertical (grupo que exibiu potencialização, GP; grupo que não potencializou, GNP). Para o total de 27 atletas o modelo final que incluiu a SMAX (km·h-1), a CR (mL·kg-1·m-1), o a AGVP (m·s-1), o Δ3-Pre CMJPVE (m·s-1), a FCmax (bpm) e a SSCPF (N) foi estatisticamente significativo; r2 = 0,91, F(6-26) = 35,64, P < 0,001, EES = 0,76, r2ajustado = 0,89. Por outra parte, o modelo para a predição do T10km, com variáveis independentes da prova de 10 km, incluiu a SMAX, o CR e AGVP [r2 = 0,75; F(3-26) = 22,52; P < 0,001; EES = 1,23]. As analises por grupo de desempenho indicaram efeitos principais do tempo (Tempos parciais, Laps) [F(2-52) = 12,20, P<0,001), η2 = 0,32] e do grupo [F(1-25) = 49,91; P<0,001, η2 = 0,66] assim como diferencias nas variáveis que explicaram a variância no T10km: para GAD [SMAX; SSCPF, FCMÉDIA, CV10km e Pós-0min CMJPVE, F(5-9) = 266,06; P <0,001; SSE = 0,09 min; r2AJUSTADO = 0,99]; GBD [VT2-%VO2max, o Δ6-Pre CMJEPV, CR; F(4-18) = 33,16; P <0,001, EES = 0,045 min; r2AJUSTADO = 0,88]. Adicionalmente, acharam-se equações diferentes para a predição do T10km em cada um dos grupos: GAD – [T10km (min) = 68,65 – (1,084 × SMAX) – (0,008 × SSCPF) + (0,083 × AGCARGA); r2 = 0,98]; GBD - T10km (min) = 44,75 – (1,05× SMAX) + (0,17×VT2-%VO2max) + (1,89 × CMJVME) – (0,061 × Idade); r2 = 0,89]. Enquanto aos grupos de potencialização, se acharam diferenças significativas entre os grupos na velocidade atingida só no segmento de 400 m finais e na PSE final (GNP = 8,36 ± 1,6 vs. GP = 6,8 ± 1,7; P = 0,03). Ademais, na amostra completa a potencialização correlacionou com o tempo nos 400 m finais (r = -0.42; P = 0,031) e no grupo GAD, correlacionou com a PSE (r = -0,75; P = 0,032). Em conclusão, os resultados deste estudo sugerem que as variáveis mecânicas são importantes para corredores de 10 km já que permitem explicar a variância e predizer o desempenho. Além disso, o nível de desempenho parece estar associado com diferencias neuromusculares que influenciam o ritmo de corrida, entanto que a potencialização do salto vertical parece afeitar sobre tudo a percepção do esforço.

Le sommeil, de par ses fonctions récupératrices, est essentiel à la vie. Pour autant, la modification du mode de vie et des comportements, tant sédentaires que nutritionnels, sont à l’origine d’une altération du sommeil, conduisant ensemble à des situations d’obésité. Cet excès pondéral s’accompagne fréquemment d’un syndrome d’apnées obstructives du sommeil (SAOS). Lorsque ces deux pathologies sont présentes, les troubles métaboliques s’aggravent et sont à l’origine d’une inflammation de bas grade. A notre connaissance, aucune étude ne s’est intéressée aux bénéfices d’un reconditionnement à l’exercice physique combiné à une modification des habitudes alimentaires, en dehors de ceux induits par la perte de poids, sur ces différents paramètres. L’objectif de ce travail de thèse a donc été, à partir d’une étude ancillaire, d’évaluer le sommeil d’adolescents obèses par polysomnographie (PSG) par comparaison à celui de sujets normo-pondérés. Dans l’étude principale, les effets d’un programme de 9 mois (reconditionnement à l’exercice, activités physiques adaptées, rééquilibre alimentaire) ont été évalués sur l’architecture et la durée du sommeil, le SAOS, les différents facteurs biologiques (inflammatoires, hormonaux, profils glucidique et lipidique) et sur les adaptations physiologiques à l’exercice musculaire, afin de mieux comprendre l’implication de l’endurance aérobie et des troubles du sommeil sur la santé cardio-métabolique. Trente-deux adolescents obèses (âge : 14,6 ans, z-score d’IMC= 4 ,7) ont été recrutés. Toutes les variables ont été analysées en pré et post-intervention. Les résultats montrent une durée de sommeil réduite chez les jeunes obèses avec un SAOS, diagnostiqué chez 58% d’entre eux, malgré une architecture du sommeil satisfaisante. En post-intervention, une perte de poids de 11 kg et une amélioration des paramètres d’adaptation à l’exercice maximal (PMA, VE, VO2pic…) ont été rapportées chez tous les sujets, que le SAOS soit encore, ou non, présent. En effet, ce syndrome s’est normalisé chez 46% d’entre eux. Par ailleurs, grâce à l’intervention, le sommeil s’est amélioré (qualité et quantité). Enfin, la protéine C-réactive basale du groupe SAOS, dont les valeurs atteignaient 11mg/l à l’admission, a considérablement diminué, accompagnée d’une baisse de la leptinémie et d’une hausse de l’adiponectinémie, pouvant expliquer le moindre risque cardio-métabolique. Nos résultats démontrent qu’à l’admission, l’inflammation est liée à l’obésité, alors qu’en post-intervention, sa baisse s’explique par l’augmentation de l’endurance aérobie, et ceci indépendamment du sexe, du poids, de la durée de sommeil et du SAOS. Bien que ce dernier n’ait pas été normalisé chez tous les sujets, sa prévention par l’exercice physique ainsi que celle des troubles métaboliques observés dans ces deux pathologies devrait faire partie intégrante de la prise en charge des jeunes obèses en vue d’atténuer le risque de morbi-mortalité cardiovasculaire à l’âge adulte / Sleep, through its restorative functions, is essential for life. However, lifestyle modifications, sedentary and unhealthy feeding behaviors trigger sleep curtailment and sleep disruption, leading together to weight gain. Obesity is usually associated with obstructive sleep apnea (OSA), and these two diseases both induce metabolic dysfunctions and low-grade systemic inflammation. To the best of our knowledge, no study has assessed the effects of exercise reconditioning and modified food habits on these parameters. The purpose of this work was to assess and compare, from an ancillary study, polysomnographic variables between obese adolescents and normal-weight (NW) controls. In the main study, the effects of a 9-month program (exercise reconditioning, adapted physical activities and modified food habits) on sleep architecture, sleep duration, OSA, biological factors (inflammatory, hormonal, carbohydrates and lipid profiles) and physiological adaptations at exercise were assessed, in order to a better understanding of the roles of cardiorespiratory fitness and sleep disorders on cardio-metabolic health. Thirty-two obese adolescents (age: 14.6 years, BMI z-score: 4.7) were recruited. Every parameters were assessed at admission and post-intervention. Short sleep duration and a high prevalence of OSA (58%) were observed at admission in obese adolescents despite a satisfying sleep architecture, compared with NW controls. Post-intervention, weight loss (11kg) and improved parameters of physiological adaptations at exercise (MAP, VE, VO2peak) were found in every subject and OSA was normalized in 46% of them. Sleep quantity and sleep quality were improved. Decreased C-reactive protein (6.78 vs 10.98 mg/l) and leptin concentrations, and increased adiponectin levels were found, and cardio-metabolic risk (CMR) was decreased. At admission, obesity explains by itself the systemic inflammation whereas the decrease in inflammation, post-intervention, is explained by enhanced cardiorespiratory fitness related to fat-free mass, after controlling for sex, weight loss, change in sleep duration and OSA. Prevention of OSA and metabolic dysfunctions by chronic exercise should be an integral part of the obesity management in youths in order to decrease the risk of cardiovascular morbi-mortality in adulthood

The prevalence of low back pain (LBP) is higher in pregnant women compared to women of the same age in a general population. Pregnancy-related LBP persists 6 years after pregnancy in 16% of women. Consequently, pregnancy represents a specific risk for LBP and persistent LBP. Pregnancy-related LBP is usually studied as a single entity, however, only one subgroup of LBP, i.e. pelvic girdle pain (PGP), seems to be associated with pregnancy. Accordingly, possible differences in subgroups of patients with LBP are unknown. The aims of this thesis were the following: 1) to describe the prevalence of clinically classified subgroups of women with LBP in a cohort (no LBP, lumbar pain, PGP, and combined pain (PGP and lumbar pain)) during pregnancy and postpartum, and 2) to determine if there was a disparity in the course, health-related quality of life (HRQL), pain intensity, disability, depressive symptoms, or muscle function in subgroups of the cohort, and 3) to identify predictors for having persistent pregnancy-related PGP postpartum. Consecutively-enrolled pregnant women were classified into LBP subgroups by mechanical assessment of the lumbar spine, pelvic pain provocation tests, standard history, and pain drawings. All women answered questionnaires (background data, EQ-5D). Women with LBP completed the Oswestry Disability Index and pain measures. The Edinburgh Postnatal Depression Scale was used to evaluate depressive symptoms at 3 months postpartum (cut-off ≥10). Trunk muscle endurance, hip muscle strength, and gait speed were investigated. Multiple logistic regression was used to identify predictors from self-reports and clinical examination. At the 12-18 gestational week evaluation, 118/308 (38%) women had no LBP, 33 (11%) had lumbar pain, 101 (33%) had PGP, and 56 (18%) had combined pain. Three months postpartum, 183/272 (67%) women had no LBP, 29 (11%) had lumbar pain, 46 (17%) had PGP, and 14 (5%) had combined pain. Pregnant women with combined pain were most affected in terms of HRQL, pain intensity, and disability. Depressive symptoms were three times more prevalent in women with LBP (27/87, 31%) than in women without LBP (17/180, 9%). Women with PGP and/or combined pain had lower values for trunk muscle endurance, hip extensor strength and gait speed compared to women without LBP. Postpartum, 16-20% of the women had persistent combined pain or PGP, whereas 1/29 had lumbar pain. Predictors for persistent PGP or combined pain were work dissatisfaction, older age, combined pain in early pregnancy, and low endurance of the back flexors. In conclusion, women with combined pain were identified to be a target group since they had the lowest recovery rate and since the classification of combined pain was found to be a predictor for persistent PGP or combined pain postpartum. The hypothesis of an association between muscle dysfunction and PGP was strengthened. Based on the finding of high comorbidity of postpartum depressive symptoms and LBP, it seems important to screen for and consider treatment strategies for both symptoms.

Le marché des mémoires non volatiles à grille flottante connaît actuellement un essor considérable du fait de leur utilisation croissante dans tous les domaines d'applications de l'électronique et par conséquent dans de très nombreux secteurs industriels. Cependant ces dispositifs mémoires se heurtent aujourd'hui à une limite technologique liée à l'impossibilité de réduire l'épaisseur de la couche d'oxyde tunnel SiO$_{2}$ qui isole la grille flottante contenant l'information. En effet, en deçà d'une épaisseur critique de l'ordre de $7\,nm$, l'oxyde tunnel est le siège de courants de fuite induits par les cycles répétés de programmation, qui engendrent des pertes de charge diminuant drastiquement le temps de rétention et la durée de vie des cellules mémoires. Ces courants de fuite sont communément appelés courants SILC (Stress Induced Leakage Current).<br /><br />Durant cette thèse, dans l'objectif d'obtenir des mesures fiables des courants SILC, nous avons mis en \oe uvre un banc de mesure très bas niveau permettant d'atteindre la résolution ($10^{-15}\,A$) des appareillages de mesures les plus performants du marché. Nous avons ensuite implémenté la technique dite "de la grille flottante" qui permet d'atteindre de façon indirecte des niveaux de courant inférieurs à $10^{-16}\,A$. À partir de nombreuses mesures expérimentales réalisées sur des oxydes tunnel de $7 - 8\,nm$ issus d'une technologie FLOTOX\ EEPROM, un modèle de conduction tunnel assisté par pièges a été développé permettant, à l'aide d'une nouvelle méthodologie, d'extraire les profils de distributions spatiale et énergétique des défauts dans l'oxyde. Le chargement stable de ces défauts permet de rendre compte de la dérive de la loi Fowler-Nordheim responsable de la fermeture de fenêtre de programmation des cellules mémoires. Le modèle développé conduit finalement à une bonne simulation des caractéristiques de conduction de l'oxyde tunnel dans tous les domaines de champ électrique et en fonction du niveau de dégradation.<br /><br />Finalement, les structures à grille flottante ont été modélisées d'un point de vue dynamique. L'influence des pulses de programmation sur les différentes grandeurs électriques dans les cellules mémoire a été analysée ainsi que les cinétiques de perte de charge en fonction du courant de fuite dans l'oxyde tunnel. A partir des mesures réalisées sur des structures de test grille flottante, les temps de rétention sur cellule élémentaire ont été extrapolés.

Tikslas – nustatyti kineziterapijos poveikį slaugytojų, dirbančių slaugos skyriuje, juosmeninės stuburo dalies skausmui ir funkcijai. Tyrimo hipotezė – galvojame, kad naudojant juosmeninės stuburo dalies raumenis stiprinančius pratimus bei juosmens tempimą Saunders aparatu juosmeninės stuburo dalies skausmas mažės, o funkcija – gerės. Stuburo ligos yra labai paplitusios visame pasaulyje: apie 80 proc. pasaulio gyventojų bent kartą yra jautę vienokio ar kitokio intensyvumo nugaros skausmą. Apie 20 proc. gyventojų periodiškai pasikartoja nugaros skausmas, trunkantis tris ir daugiau dienų (Seibutis, 2008). Nugaros juosmeninės dalies skausmas yra labai paplitęs, dažniausiai jis nustatomas darbingo amžiaus žmonėms nuo 30 iki 50 metų amžiaus (Secer ir kt., 2009). Temos aktualumas – slaugos skyriuje dirbančiam personalui tenka susidurti su slaugos priemonių ir kėlimo įrangos stoka bei dideliu darbo krūviu, todėl personalas skundžasi varginančiais stuburo skausmais dėl netaisyklingo pacientų kėlimo ir vartymo (Aw et al., 2013). Užsienio autorių (d'Errico et al., 2013) atliktuose tyrimuose buvo nustatyta, kad dirbančių slaugytojų tarpe ypatingai dažnas yra juosmeninės stuburo dalies skausmas, kurį būtina kontroliuoti ir imtis priemonių nedarbingumui dėl jo mažinti. Temos naujumas – mokslinių tyrimų ir straipsnių apie slaugos skyriuje dirbančių slaugytojų nugaros juosmeninės dalies skausmus nėra daug. Kadangi slaugos skyriuose dirbančių slaugytojų darbo sąlygoms ir tenkančiam krūviui... [toliau žr. visą tekstą] / Object: to determine the effects of physical therapy for nurses working in the nursing section of the lumbar spine pain and function. Hypothesis of research – we think that the use of lumbar spine exercises and lumbar strain Saunders apparatus lumbar spine pain will decrease and the function is going to get better. Spinal diseases are very common in all world: about 80 percent of world population at least once felt one or another back pain intensity. About 20 percent of population back pain, lasting for three or more days is periodically recurring (Seibutis, 2008). Low back pain is a very common disorder, but mostly is determinated for able – bodied persons aged from 30 till 50 years old (Secer et al., 2009). Relevance of the subject – in the care unit working staff have to deal with the lack of nursing tools and lifting equipment and a heavy workload, because staff complaining to of troublesome of low back pain about incorrect patient lifting and turning (Aw et al., 2013). Previous investigations of foreign authors, it was found that nurses working in particular among frequent is pain in the lumbar spine, which it is necessary to monitor the occurrence of and to take measures for its reduction (d'Errico et al., 2013). Newness of the subject – research and articles about nursing for nurses working in the section of the back lumbar pain is not a lot of. Whereas the sections working in nursing nurses working conditions and the lack of attention given to the workload, decreasing... [to full text]

For paper producers, an understanding of the development of strength properties in the paper is of uttermost importance. Strong papers are important operators both in the traditional paper industry as well as in new fields of application, such as fibre-based packaging, furniture and light-weight building material. In the work reported in this thesis, three approaches to increasing paper strength were addressed: mixing different pulps, multilayering and reinforcement with man-made fibres. In specific: The effects of mixing Swedish softwood kraft pulp with southern pine or with abaca (Musa Textilis) were investigated. Handsheets of a softwood kraft pulp with the addition of abaca fibres were made in a conventional sheet former. It was seen that the addition of abaca fibres increased the tearing resistance, fracture toughness, folding endurance and air permeance. Tensile strength, tensile stiffness and tensile energy absorption, however, decreased somewhat. Still it was possible to add up to about 60% abaca without any great loss in tensile strength. As an example, with the addition of 30% abaca, the tear index was increased by 36%, while the tensile index was decreased by 8%. To study the effect of stratification, a handsheet former for the production of stratified sheets, the LB Multilayer Handsheet Former was evaluated. The advantage of this sheet former is that it forms a stratified sheet at low consistency giving a good ply bond. It was shown to produce sheets with good formation and the uniformity, evaluated as the variation of paper properties, is retained at a fairly constant level when the number of layers in the stratified sheets is increased. The uniformity of the sheets produced in the LB Multilayer Handsheet Former is generally at the same level as of those produced in conventional sheet formers. The effects of placing southern pine and abaca in separate layers, rather than mixing them homogeneously with softwood pulp were studied. Homogeneous and stratified sheets composed of softwood and southern pine or softwood and abaca were produced in the LB Multilayer Handsheet Former. It was found that by stratifying a sheet, so that a pulp with a high tear index and a pulp with a high tensile index are placed in separate layers, it was possible to increase the tear index by approximately 25%, while the tensile index was decreased by 10-20%. Further, by mixing a pulp with less conformable fibres and no fines with a pulp with more flexible fibres and fines, a synergy in tensile strength (greater strength than that predicted by linear mass fraction additivity) was obtained. The effects of stratifying sheets composed of softwood and abaca were compared to the effects of refining the softwood pulp. Homogeneous and stratified sheets composed of softwood with three different dewatering resistances and abaca were also produced in the LB Multilayer Handsheet Former. It was found that by stratifying the sheets the tear index was retained while the tensile index was increased by the refining. The effects of reinforcing softwood pulp of different dewatering resistances with man-made fibres with low bonding ability were also investigated. Man-made fibres (i.e. regenerated cellulose, polyester and glass fibres) were added in the amounts 1, 3, or 5 wt% to softwood pulp of three different dewatering resistances. It was found that with refining of a softwood pulp and subsequent addition of long fibres with low bonding ability the tensile-tear relationship can be shifted towards higher strength values. The bonding ability of the man-made fibres was evaluated by pull-out tests and the results indicated that, in relation to the fibre strength, regenerated cellulose (lyocell) was most firmly attached to the softwood network while the glass fibres were most loosely attached.

Diss. (sammanfattning) Stockholm : Karol inst., 2004. / Härtill 5 uppsatser.