Yhdensuuntaislujitteiden pakkautuvuuden kokeellinen määrittäminen

The problem of the Vacuum Injection (VI) process which was considered in this thesis is low fiber content. Related literature was reviewed to investigate the influence of different VI-technique's manufacturing parameters on the compaction behaviour of unidirectional (UD) fiber reinforcements. Experimental methods were developed for testing and characterization of the compaction behaviour of UD fiber reinforcements. Experimental setup and equipment were designed and built. Experimental program, procedure and tests properties were obtained. Dry and wet tests were performed. Unidirectional glass fiber reinforcements were tested in dry tests to obtain the effect of number of performs layers and their sizing, amount of vacuum pressure, compaction time and number of the vacuum pressure cycles on compaction. The effect of the different factors on compaction was investigated by testing unidirectional fiber reinforcements in the VI-process. Wet tests were performed to obtain the effect of the pressure gradient and resin viscosity on compaction. During the tests the thickness of specimens was recorded. The data were processed and the plots were produced. Results were studied in the plot, calculation and table form. The dry test results revealed that the compaction behaviour of the fabrics depends on the combination of the factors such as test implementation method, stitch amount, formation and tension, therefore their comparison becomes complex. Lower stitch tension has roving nesting advantages. Both in the fresh and non-fresh fiber cases, the thickness of the stack increases with a fairly accuracy linearly as a function of the number of layers. The compaction time and roving nesting suggested as a cause that the effect of vacuum pressure on thickness decreases when vacuum pressure is gradually increased. Compaction increases with vacuum pressure processing to 25% in average depending on material and implementation method. In order to define the real behaviour of the different lay-up styles more tests are needed. The tests confirmed that compaction cycles compacted the fibers depending on material and implementation method in average two and half percentage units more effectively than the compaction time. Compaction increases with the number of the pressure cycle reaching values to 3.00% in average depending on material and implementation method. The tests confirmed that depending on the material in average compaction increases between 0.38 ... 1.00% and 0.05% in the first and second ten minutes and the effect of compaction time continues to become less relevant after 20 minutes. Based on the wet test results a suggestion was made on controlling the compaction behaviour of the fabrics which depends on the combination of the factors such as test implementation method, pressure gradient and corresponding compaction expansion-compaction cycle. Compaction increases noticeably with decreasing resin viscosity rate up to approximately 15%. In all dry test and injection cases compaction varies with cycle time and processing speed rate.Alipaineinjektio prosessin ongelma, jota tutkittiin tässä opinnäytetyössä on alhainen kuitupitoisuus. Tässä diplomityössä selviteltiin miten eri parametrit vaikututtavat yhdensuuntaislujitteiden pakkautuvuuteen. Kirjallisuustutkimuksella selviteltiin pakkautuvuuden tutkimuksissa käytetyt koemenetelmät, niiden soveltuvuus sekä eri parametrien vaikutukset pakkautuvuuteen. Niiden pohjalta kehitettiin, suunniteltiin ja toteutettiin koejärjestely, mittausmenetelmä ja koeohjelma yhdensuuntaislujitteiden pakkautuvuuden kokeelliseen määrittämiseen. Pakkautuvuus määritettiin kuiville ja nestemäisen hartsin kyllästämille lujitteille. Kuivalla lujitteella tutkittiin lujitteen pinnoitteen sekä kerrosten lukumäärään, alipaineen, pakkautuvuusajan ja alipainesyklien lukumäärään vaikutukset. Injektiokokeella, jota kutsutaan tässä diplomityössä myös märkäkokeeksi, tutkittiin toteutusmenetelmän, paineen ja erityisesti painegradientin sekä hartsin viskositeetin vaikutukset lujitteen pakkautuvuuteen. Kokeiden aikana koekappaleiden paksuuden käyttäytymistä seurattiin. Koetulokset koottiin kuviin ja taulukoihin. Kuivakokeiden tulokset osoittivat, että lujitteiden pakkautuvuuskäyttäytymisen vertailusta tulee monimutkainen, koska pakkautuvuus riippuu eri tekijöiden yhdistelmästä, kuten kokeen toteutustavasta, koekappaleen tikkien määrästä, niiden tyypistä ja kireydestä. Sekä tuoreiden että ei-tuoreiden lujitteiden tapauksissa pinon paksuus kasvaa melko hyvällä tarkkuudella lineaarisesti kerrosten lukumäärän funktiona. Pakkautuvuusaikaa ja rovingien eli lasikuitukimppujen sijoittelua ehdotettiin perusteluksi, että alipaineen vaikutus koekappaleen paksuuteen vähenee kun alipaine kasvatetaan asteittain. Toteutustavasta ja materiaalista riippuen pakkautuvuus on alipaineen vaikutuksessa keskimäärin 25 %. Kerrosten sijoittelutyylin vaikutuksen arviointi edellyttää lisäkokeita. Pakkautuvuusaikakokeet vahvistivat, että materiaalista riippuen pakkautuvuus vaihtelee keskimäärin välillä 0,38 ... 1,00 % ja 0,05 % ensimmäisessä ja toisessa kymmenen minuutissa, 20 minuutin jälkeen pakkautuvuusajan merkitys on hyvin vähäinen. Injektiokoetuloksen perusteella pakkautuvuuskäyttäytyminen riippuu kokeiden toteutustavasta, paineesta ja vastaavasta pakkautuvuus-laajennus-pakkautuvuus syklistä sekä hartsisysteemin viskositeetista. Injektiokoetuloksen perustella tehtiin ehdotuksia pakkautuvuuskäyttäytymisen kontrolloimiselle. Pakkautuvuus kasvaa huomattavasti hartsin viskositeetin laskiessa. Kaikissa kuivakokeissa sekä injektiotapauksissa pakkautuvuus vaihteli aikasyklin ja käsittelynopeuden mukaan

The Nonlinear Bending Analysis for Circular Nano Plates Based on Modified Coupled Stress and Three- Dimensional Elasticity Theories

In this paper, the nonlinear bending analysis for annular circular nano plates is conducted based on the modified coupled stress and three-dimensional elasticity theories. For this purpose, the equilibrium equations, considering nonlinear strain terms, are calculated using the least energy potential method and solved by the numerical semi-analytical polynomial method. According to the previous works, there have been no studies calculating all boundary conditions numerically based on three-dimensional elasticity. Typically, the research done on three-dimensional elasticity is either finite element or only for a simply-supported boundary condition. In this research, for the first time, the nonlinear analysis of bending is calculated with the help of three-dimensional elasticity for a variety of boundary conditions. Also, with the help of the modified couple stress theory, the results on the nano-scale scale have been studied. In the following, while validating the results, we investigate the changes in the scale parameter for the types of boundary conditions, the effect of changing the parameter of scale in different thicknesses, and the impact of the parameter of scale on the linear and nonlinear results

Developing a Procurement and Supplier Classification Model for Civil Aviation Engine Maintenance, Repail and Overhaul. Case X

The purpose of this research is to develop a procurement and supplier classification model for the case company, X. At the first phase of the thesis, primary research in the form of personnel interviews was planned and implemented to understand the situation at the case company. Simultaneously, secondary research was carried out to support the implementation of the interviews as well as to build the theoretical framework for this thesis. Secondary research was employed to discover the theoretical background related to procurement and supplier classification analyses. There are a number of methods for analyzing businesses. However, the methods used in this thesis were the spend analysis, Kraljic’s portfolio analysis and the ABC analysis, which ranks a group of selected items, for example, spare parts according to the volume of purchasing in terms of money. At the second phase of the thesis, all discoveries from phase 1 were employed to analyze the purchasing statistics and develop a classification model suitable for the case company. Thus, the theoretical learnings and the interview results were integrated with the analyses of the purchasing statistics of direct procurement for 2017-2018 to develop a procurement and supplier classification model. At the third phase of the research, the key results from phases 1 and 2 of the thesis were emphasized. These results were further assessed to evaluate their validity and reliability. Finally, all findings from phases 1, 2 and 3 were combined to offer recommendations to the case company. The recommendations focus was on improving the procurement operation of the case company in terms of direct purchasing through the classification of procurement and supplier

Diversity of lactic acid bacteria isolated from Kurdish ewe\u27s milk cheese

A total of 166 lactic acid bacteria were isolated from Khorasan Kurdish ewes\u27 milk cheese and identified phenotypically. They belonged to six genera and 26 species. Of the isolates, 65.7% were identified as Lactobacilli, 13.3% as Lactococci, 9.6% as Pediococci, 6.0% as Enterococci, 3.6% as Leuconostocs and 1.8% as Weissella. Lactobacilli were subdivided into three main groups: facultatively heterofermentative (30.12%); obligately heterofermentative (25.3%); and obligately homofermentative (10.24%). Lc. lactis subsp. lactis, Lb. plantarum, Lb. brevis, Lb. helveticus and Lb. buchneri were the dominant species of all the LABs isolated from the samples, while the dominant species of each genus were Lb. plantarum, Lc. lactis subsp. lactis, P. acidilactici, E. faecum, Leu. lactis and W. confusa. Non-starter lactic acid bacteria (NSLAB) constituted 73% of all isolates

Perinatal maternal probiotic intervention impacts immune responses and ileal mucin gene expression in a rat model of irritable bowel syndrome

Alterations in immune responses and intestinal secretory state are among features commonly observed in the maternal separation (MS) rat model of Irritable Bowel Syndrome. This study examined whether perinatal maternal introduction of probiotics influences plasma immune markers and ileal mucin-2 (MUC2) gene expression in rat offspring exposed to neonatal maternal separation (MS, 3 h/day, postnatal days (PND) 2-14) and/or subsequently to acute restraint stress in adulthood (AS, 30 min/day, PND 83-85). Data analysis indicated that stress protocols did not affect plasma tumour necrosis factor alpha (TNF-α), interferon gamma (IFN-γ) and interleukin (IL)-6 levels in young offspring (PND 24) born to the vehicle-treated dams. Maternal probiotic intervention was associated with significantly decreased IFN-γ levels in young offspring compared with non-probiotic offspring (P≤0.05). It also induced a significant increase in IL-6 levels in MS pups (P≤0.05). Exposure of both non-MS and MS offspring to AS induced a significant increase in haptoglobin levels compared to controls (P≤0.05), whereas all offspring born to the probiotic-treated dams, irrespective of stress treatment conditions, exhibited significantly decreased haptoglobin levels to well below the control levels (P≤0.05). MS and/or AS did not affect ileal expression of MUC2 in offspring born to the non-probiotic treated dams. While maternal probiotic intake significantly downregulated ileal gene expression of MUC2 in MS male young offspring, it was associated with significantly upregulated MUC2 mRNA expression in MS or AS adult male offspring. These findings suggest that maternal probiotic intervention may exert long-lasting anti-inflammatory effects and impact gut outcomes in offspring at increased risk of dysfunctional gut

Perinatal maternal probiotic intervention impacts immune responses and ileal mucin gene expression in a rat model of irritable bowel syndrome

Alterations in immune responses and intestinal secretory state are among features commonly observed in the maternal separation (MS) rat model of Irritable Bowel Syndrome. This study examined whether perinatal maternal introduction of probiotics influences plasma immune markers and ileal mucin-2 (MUC2) gene expression in rat offspring exposed to neonatal maternal separation (MS, 3 h/day, postnatal days (PND) 2-14) and/or subsequently to acute restraint stress in adulthood (AS, 30 min/day, PND 83-85). Data analysis indicated that stress protocols did not affect plasma tumour necrosis factor alpha (TNF-α), interferon gamma (IFN-γ) and interleukin (IL)-6 levels in young offspring (PND 24) born to the vehicle-treated dams. Maternal probiotic intervention was associated with significantly decreased IFN-γ levels in young offspring compared with non-probiotic offspring (P≤0.05). It also induced a significant increase in IL-6 levels in MS pups (P≤0.05). Exposure of both non-MS and MS offspring to AS induced a significant increase in haptoglobin levels compared to controls (P≤0.05), whereas all offspring born to the probiotic-treated dams, irrespective of stress treatment conditions, exhibited significantly decreased haptoglobin levels to well below the control levels (P≤0.05). MS and/or AS did not affect ileal expression of MUC2 in offspring born to the non-probiotic treated dams. While maternal probiotic intake significantly downregulated ileal gene expression of MUC2 in MS male young offspring, it was associated with significantly upregulated MUC2 mRNA expression in MS or AS adult male offspring. These findings suggest that maternal probiotic intervention may exert long-lasting anti-inflammatory effects and impact gut outcomes in offspring at increased risk of dysfunctional gut

Effect of maternal probiotic intervention on HPA Axis, immunity and gut microbiota in a rat model of irritable bowel syndrome

Objective: To examine whether maternal probiotic intervention influences the alterations in the brain-immune-gut axis induced by neonatal maternal separation (MS) and/or restraint stress in adulthood (AS) in Wistar rats. Design: Dams had free access to drinking water supplemented with Bifidobacterium animalis subsp lactis BB-12® (3x109 CFU/mL) and Propionibacterium jensenii 702 (8.0x108 CFU/mL) from 10 days before conception until postnatal day (PND) 22 (weaning day), or to control ad lib water. Offspring were subjected to MS from PND 2 to 14 or left undisturbed. From PND 83 to 85, animals underwent 30 min/day AS, or were left undisturbed as controls. On PND 24 and 86, blood samples were collected for corticosterone, ACTH and IgA measurement. Colonic contents were analysed for the composition of microflora and luminal IgA levels. Results: Exposure to MS significantly increased ACTH levels and neonatal fecal counts of aerobic and anaerobic bacteria, E. coli, enterococci and clostridia, but reduced plasma IgA levels compared with non-MS animals. Animals exposed to AS exhibited significantly increased ACTH and corticosterone levels, decreased aerobic bacteria and bifidobacteria, and increased Bacteroides and E. coli counts compared to non-AS animals. MS coupled with AS induced significantly decreased anaerobes and clostridia compared with the non-stress adult controls. Maternal probiotic intervention significantly increased neonatal corticosterone levels which persisted until at least week 12 in females only, and also resulted in elevated adult ACTH levels and altered neonatal microflora comparable to that of MS. However, it improved plasma IgA responses, increased enterococci and clostridia in MS adults, increased luminal IgA levels, and restored anaerobes, bifidobacteria and E. coli to normal in adults. Conclusion: Maternal probiotic intervention induced activation of neonatal stress pathways and an imbalance in gut microflora. Importantly however, it improved the immune environment of stressed animals and protected, in part, against stress-induced disturbances in adult gut microflora

Prophylactic role of maternal administration of probiotics in the prevention of irritable bowel syndrome

Neonatal stress is a common early life event which alters the development of the endocrine and immune systems. Specifically, exposure to neonatal stress results in alterations to the hypothalamic-pituitary-adrenal (HPA) axis resulting in offspring who hyper-respond to stress in adulthood. Recently, this concept has been applied to the ontogeny of functional gastrointestinal (GI) disturbances such as irritable bowel syndrome (IBS). The high prevalence of this disorder and the ineffectiveness of current treatments results in high direct and indirect costs to the society. Recently, administration of probiotics to neonates has been used as a safe and cost-effective preventative strategy to revoke the long term unfavourable imprinting induced on the gastrointestinal system by early life stressors in animal models of human IBS. It is not as yet known however, whether maternal supplementary probiotics may also contribute to improved GI integrity and gut-associated immune functioning in stressed neonates, if these possible improvements persist into adulthood, or how this protective effect may be mediated. Our hypothesis is an attempt to link this proposed nutritional approach and its possible preventive effects against GI dysfunctions provoked by neonatal stress. Crown Copyright © 2009