The Dielectric Barrier Discharge (DBD) plasma actuators have received a significant attention of many researchers in the last few decades. The main focus of these studies has been on the flow control areas such as turbulent boundary layer separation and turbulent skin friction reduction. Little attention has been paid on the effect of the DBD plasma actuators on the aerodynamic noise reduction. In this regard, the aim of the current work is to investigate the effect of the DBD plasma actuator driven at relatively low voltages on vortex-induced noise. The first part of the current work includes an extensive assessment of the effect of the DBD plasma actuator on the narrowband tonal noise radiated from a flat plate with blunt trailing edge and an airfoil (NACA 0012) with blunt and cut-in type serrated trailing edge. The measurements were carried out at Reynolds numbers between 0.75 x 10 to the power of 5 and 4 x 10 to the power of 5. It is found that the DBD plasma actuator effectiveness depends on the direction of the generated electric wind. For example, a high reduction in the narrowband tonal noise level is achieved when a direct streamwise electric wind is injected into the wake region. However, using a plasma actuator, which can induce streamwise vortices into the wake region, shows more superior noise reduction capability at lower voltages. Flow measurement results revealed that the mechanism responsible for the narrowband tonal noise reduction when the electric wind is directly injected into the wake is not due the momentum injection into the wake deficit. Rather, the streamwise jet isolates the two separated shear layers and prevents the interaction between them. On the other hand, it is found that the break-up of the spanwise coherence of the vortex shedding is responsible for the significant reduction in the tonal noise level when the spanwise actuation is used. The second part of the current work comprises the effect of the DBD plasma actuator on both the narrowband tonal noise and interaction broadband noise radiated from both single and tandem cylinder, respectively. The experiments were conducted at subcritical Reynolds number ReD = 1.1 x 10 to the power of 4. The actuators were positioned at different azimuthal angles 27° ≤ θj ≤ 153°. For the single cylinder case, the acoustic results show the DBD plasma actuator that is positioned at θj = 133° leads to a more reduction in the narrowband tonal noise level when compared to the other angles. It is found that the streamwise jet produced by the plasma actuators plays an important role in prevention of the interaction between the shear layers that separates from the cylinder. For the tandem cylinders case, the acoustic results show that the simultaneous actuation of both the upstream and the downstream cylinders leads to more reduction in both the narrowband tonal noise and the interaction broadband noise level compared with the case where only the upstream or the downstream cylinder is actuated. The mechanism responsible for this noise reduction is found to be mainly due to the streamwise jet induced by the upstream cylinder activation, which delays the vortex shedding formation and reduces the turbulence intensity in the near wake region. On the other hand, the plasma induced jet against the main-flow direction works as a virtual fluidic barrier which displaces the wake produced by the upstream cylinder away from the downstream cylinder.

The master's thesis consists on possibilities of finding a new small business and verifying his realization. I take the informations from feasibility study, opportunity study and also from analysis of strengths and weaknesses SWOT. The proposal part of the thesis draws on analytical part and there is also the presentation of future company and draft of the proposal realization.

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In today’s World, sustainability is not just a buzz word but should be the new quality. In order to live in a pollution free environment, there is an urgent need to move towards a circular economy. The rapidly increasing demand of textiles results in high amount of textile waste leading to pollution. Textile to textile recycling is the most feasible solution to minimize textile waste while meeting the fashion demand. Mechanical recycling by shredding is one way of recycling textiles where, fabrics are broken down into their constituent fibres. The problem with this method is that, after shredding, there is huge reduction in fibre length due to the harsh process. This makes it difficult to use a high percentage of these reclaimed fibres in formation of new textile garments. The main focus of this thesis was to reduce the fibre length drop that occurs during shredding through lubricant pretreatment. It was anticipated that, inter-fibre friction would be the reason for the huge fibre length drop during shredding. Therefore, a method was developed to measure the inter-fibre friction of cotton and polyester staple fibres using a tensile tester. The effect of blending on inter-fibre friction was investigated. Different types of lubricants were used to alter the inter fibre friction. The lubricants were sprayed on the fibres and dried prior to carding. Two lubricants were chosen for pretreatment of fibres for yarn formation. The effect of the lubricant on the inter-fibre friction of carded fibre webs as well as yarn strength and spinnability were investigated. The results showed that, the method developed can be used to measure inter-fibre friction of staple fibres. It was also found that, inter-fibre friction in carded webs depends on the crimp and mechanical interlocking in the web. Inter-fibre friction in blended fibres depends on the percentage amount of each fibre in the blend. Addition of a small amount of lubricant significantly lowers the inter-fibre friction. The effect depends on the type of lubricant and type of fibre. Lubricant amount above 1.43% on weight of fibre lead to poor carding of fibres. Lubricant amounts between 0.29 % and 1% on weight of fibre lead to good carding of cotton and polyester fibres but the cotton fibre webs may not be spun. PEG4000 lubricant was found to significantly lower the inter-fibre friction compared to other lubricants. It was also found that, lubricants significantly affect the tensile strength of the yarn as well as their spinnability. Basing on the results, it was concluded that, lubricant pretreatment of fabrics prior to shredding will most likely provide a more gentle process. This was based on the fact that, the lubricants reduce the inter-fibre friction. This enables easier slippage of fibres within the yarns which facilitates easier deformation of the yarns during the shredding process. Thus reduce the fibre length drop. PEG 4000 is more likely to provide better results when used in amounts ranging from 0.1 to 0.71% on weight of fabric. Besides that, PEG is safe for the environment.

In 2015 the global fibre consumption was 96.7 million tonnes, which is an increase of 3.1% from the year before. Our high textile consumption has led to an increasing demand of raw materials and generation of textile waste. Only in Europe, a total amount of 4.3 million tonnes of apparel waste each year is sent to either incineration or landfills. Approximately 50% of the clothes we discard and donate are composed of cotton. In the future, the cotton production is predicted to stagnate since the world population is increasing and arable land to greater extent will be needed for food production. Thereby, it is important that we utilize the cotton waste generated. One of the most commonly used processes for recycling textile waste is the shredding process. In this method, textile waste is shredded back into their constituent fibres. The drawback with the shredding process is that the fibre length is reduced. The fibre length is an important property since it has a high influence on textile processing such as yarn production and final product quality. The aim of this thesis was to investigate how post-consumer cotton garments with different degree of wear affects the fibre length obtained in the shredding process. This was performed by analysing the input fibre length as well as the output fibre length. Additionally, several parameters were investigated: fabric construction and yarn structure. Degree of wear was categorized into two levels: low and high degree of wear. The fabric constructions used in this study were single-jersey and denim. The yarn structure were analysed in terms of yarn count, yarn twist and manufacturing process.  The result showed that the fibre length before shredding was statistically significant longer for the materials with low degree of wear compared to high degree of wear. After shredding, it was shown that the fibre length reduction was lower for the materials with high degree of wear. This indicates that longer fibres give higher fibre length reduction. In addition, it was found that finer yarn gives higher fibre length reduction. The result also showed that the yarn manufacturing process has a great influence on the ease of shredding and the fibre length obtained in the end.  Based on the result in this thesis it can be concluded that the shredding process needs to be improved in order to preserve the fibre length. The area of post-consumer textile waste is complex and the result showed that there is many underlying parameters that need to be taken into account to further develop the shredding process.

Stream ecosystems can be influenced by cattle grazing in the riparian zone due to sediment input, nutrient loading, and soil compaction, which lead to alterations of macroinvertebrate and microbial activity. Recently government programs, such as the Conservation Reserve Enhancement Program (CREP), have provided funding for farmers to exclude cattle from streams and riparian zones. Funding for CREP is limited and does not allow for post exclusion assessment. The objectives for this study were; 1) to explore whether CREP and other cattle exclusion initiatives help restore functional integrity to streams; 2) and if they do, to evaluate the time required for integrity to be restored. I predicted leaf processing (a fundamental ecosystem level function) in streams would be influenced by excluding cattle from the riparian zone due to changes in nutrient availability, sediment abundance, shredding macroinvertebrates, and microbial activity. I tested this prediction by measuring leaf processing at sites that had cattle excluded for <1 to 15 years. Breakdown rates did not correspond linearly to time since cattle exclusion. This was probably due to the opposing effects of elevated sediment versus nutrients on leaf breakdown at recently grazed sites. Leaf breakdown and shredder density were strongly correlated with riparian vegetation density. This study suggests that in addition to cattle exclusion, reforestation of woody riparian vegetation may be essential to restore functional integrity to agricultural streams. / Master of Science

Mountaintop removal and valley fill (MTRVF) mining has become a widespread means of coal extraction in the central Appalachians. During MTRVF several hundred meters of overburden are removed to access coal seams, and excess rubble is dumped into adjoining valleys and streams. Filling valleys eliminates stream headwaters and may result in loss of stream ecosystem functions, which are dependent on temporal and lateral connectivity in river networks. To determine the affect of MTRVF on stream ecosystem function, leaf breakdown, which is an ecosystem level attribute of forested streams, was measured in five streams draining MTRVF sites and five reference streams in central West Virginia. Leaf packs of white oak and red maple were installed in these streams in December 2007, leaves were collected in January, February, March, April, and June of 2008, and leaves were washed and processed in the lab. Leaf breakdown rates were significantly slower in filled streams. MTRVF streams were marked by high sediment levels, elevated base flow, elevated conductivity and pH, and a lower density and richness of shredding macroinvertebrates than reference sites, suggesting that slower leaf decay was the result of the combined set of altered conditions in MTRVF streams. Additionally, MTRVF streams showed no species-level difference between red maple and white oak breakdown rates, indicating that MTRVF inhibits control of ecosystem function exerted by leaf species characteristics. / Master of Science

There is a growing need for fibres with increasing population. One way to solve this is to recycle the fibres from textile waste. In mechanical recycling by shredding the textiles are shredded back to fibrous form. The biggest problem with shredding is that it is a harsh process that reduces the fibre length and damages the fibre.   To make the shredding process more gentle and preserve more of the fibre length, pre-treatment that lowers the friction between the fibres have been investigated. Polyethene glycol 4000 (PEG 4000) is an environmentally friendly chemical that could be used to lower the friction of cotton and polyester, the two most used textile fibres. Another treatment evaluated is glycerol. The treatment should not affect further processing of the fibres. For evaluating the treatment, a test of the interfibre friction was performed on carded webs and fabrics that were untreated and treated. Prior to shredding four samples were made of fabrics of cotton, polyester and polycotton. From each fabric, one was left untreated, and one was treated with a low concentration of PEG 4000. The concentration of PEG 4000 was chosen from the test on fibres. Also from each fabric, two treatments that were not prepared by the author; one with a high concentration of PEG 4000 and the other with glycerol. All 12 samples were shredded back to fibres. The shredded material was analysed, and the fibre length was measured. The reclaimed fibres from the shredded material were also tried to be processed into yarns.   The main result was that it was possible to rotor spin yarn of 100% reclaimed fibres from cotton and polyester treated with PEG 4000, which means that the treatment did not interfere with the spinnability of the reclaimed fibres. Untreated cotton was also spinnable, but untreated polyester was not possible to card. The cotton and polyester treated with glycerol were possible to carded and made into a sliver but not spinnable. The reclaimed fibres from the polycotton fabric were not possible to card or process further. This result correlates with the analyses of the shredded material and the fibre length measurement. The best results were for polyester treated with 0.71 w% PEG 4000 that had 121% longer mean fibre length than untreated polyester. The best result for cotton was treated with 0.29 w% PEG 4000.

Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-05-04T14:32:46Z No. of bitstreams: 1 marcospereiralopes.pdf: 2209315 bytes, checksum: 7fb3d297f8d26fb98f07a65d24dfd96f (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-17T13:31:19Z (GMT) No. of bitstreams: 1 marcospereiralopes.pdf: 2209315 bytes, checksum: 7fb3d297f8d26fb98f07a65d24dfd96f (MD5) / Made available in DSpace on 2017-05-17T13:31:19Z (GMT). No. of bitstreams: 1 marcospereiralopes.pdf: 2209315 bytes, checksum: 7fb3d297f8d26fb98f07a65d24dfd96f (MD5) Previous issue date: 2014-02-28 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Na região tropical são escassos os estudos que exploram o uso do processo de decomposição foliar como ferramenta funcional para avaliar os efeitos das perturbações antrópicas sobre os ecossistemas aquáticos. Nosso objetivo foi avaliar os efeitos dos impactos antrópicos sobre a taxa de decomposição de Picramnia sellowii em riachos no Sudeste do Brasil. O experimento foi realizado durante 60 dias em três riachos referências e três impactados por poluição orgânica e sem cobertura vegetal. Em cada riacho foram incubados três sacos contendo 3 ± 0,05 g de folhas secas de P. sellowii. Os riachos referência apresentaram maiores concentrações de oxigênio dissolvido e menores valores de nutrientes, turbidez, condutividade elétrica, TIA (área total impermeável) e temperatura. O coeficiente de decomposição (k) diferiu entre os riachos referência (k = 0,014 ± 0,003 d-1) e os impactados (k = 0,005 ± 0,001 d-1). Nas folhas incubadas nos riachos referência foi observada maior biomassa de fungos e abundância de invertebrados, assim como a presença de fragmentadores, estando o k relacionado com a biomassa destes organismos. A decomposição se mostrou sensível para avaliar impactos antrópicos nos ecossistemas aquáticos uma vez que foram observadas nítidas diferenças entre a perda de massa foliar nos riachos referências e impactados. Estes resultados reforçam o efeito negativo da urbanização sobre a decomposição e biomassa de fungos e fragmnetadores. No segundo experimento foram realizadas retiradas após 7, 15, 30, 60, 90 e 120 dias, em três remansos e três corredeiras apenas nos riachos referências. Os principais resultados foram: no final do experimento restaram 16,63 % (remansos) e 10,30 % (corredeiras) de massa seca, que diferiu apenas entre os dias do experimento e não entre os mesohabitats e, foi influenciada pela biomassa de fungos; houve aumento na biomassa destes microorganismos no dia 90, diferindo apenas entre os dias do experimento e sendo influenciada pela temperatura e O2; a abundância de invertebrados foi maior em corredeiras e no dia 30, apresentando diferença entre mesohabitats e entre os dias, e sendo influenciada pela temperatura, O2 e velocidade; maior riqueza foi registrada em remansos e no dia 60; a família Chironomidae foi a mais abundante durante todo o experimento nos dois mesohabitats; a abundância e biomassa de fragmentadores foram baixas; o escalonamento multidimensional não métrico mostrou a separação dos mesohabitats e períodos inicial e final da decomposição. Através do segundo experimento foi possível observar que a perda de massa nos ecossistemas lóticos de baixa ordem é mais influenciada pela biomassa de fungos que pela biomassa de fragmentadores e pela velocidade da água. Adicionalmente, observamos que diferenças na abundância, riqueza e composição de invertebados são influenciadas por diferenças entre mesohabitats e pela sucessão ao longo da decomposição. Esses resultados contribuem para reforçar a importância do material vegetal de origem terrestre como fonte de energia para os invertebrados em riachos, e a necessidade de preservação da vegetação ripária. / There are few studies in tropical regions exploring the use of leaf breakdown process as a functional tool to assess anthropic disturbance on aquatic ecosystems. We assessed the effects of water pollution due to human activities on the leaf breakdown rate of Picramnia sellowii in streams of the southeastern Brazil. The experiment was carried out for 60 days in three reference streams and three streams impaired by organic pollution and absente of riparian vegetation. Three litter bags were incubated in each stream containing 3 ± 0.05 g of P. sellowii leaves. The reference streams presented higher values of dissolved oxygen and lower values of nutrients, turbidity, electrical conductivity, total impermeable area and water temperature. The leaf breakdown rate (k) differed significantly between the reference (k = 0.014 ± 0.003 d-1) and impaired streams (k = 0.005 ± 0.001 d-1). The leaves incubated in the reference streams contained greater fungal biomass (measured as ergosterol concentration) and abundance of invertebrates, as well as greater presence of shredders, with k values being related to the biomass of these organisms. Overall, there were clear differences between the leaf mass loss in the reference and impaired streams. These results reinforce the negative effect of urbanization on leaf breakdown and fungal and shredder biomass. In the second experiment were performed withdrawn after 7, 15, 30, 60, 90 and 120 days, in three backwaters and three rapids only in streams references. The main results were: at the end of the experiment remained 16.63% (backwaters) and 10.30% (rapids) of dry mass, which differed only between days of the experiment and not between mesohabitats and was influenced by fungal biomass; there was an increase in biomass of these microorganisms on day 90, differing only from the days of the experiment and being influenced by temperature and O2; the abundance of invertebrates was higher in rapids and on the 30 th, presenting difference between mesohabitats and between days, and being influenced by temperature, O2 and speed; greater richness was recorded in backwaters and day 60; the family Chironomidae was the most abundant throughout the experiment in both mesohabitats; the abundance and biomass of shredders were low; non-metric multidimensional scaling showed the separation of mesohabitats and initial and final periods of decomposition. Through the second experiment it was observed that the mass loss in the low-order stream ecosystems is more influenced by the biomass of fungi that the biomass of shredders and the velocity of the water. Additionally, we found that differences in the abundance, richness and composition invertebados are influenced by differences between mesohabitats and the succession in the decomposition. These results help to reinforce the importance of plant material of terrestrial origin as an energy source for invertebrates in streams, and the need for preservation of riparian vegetation.

Denna rapport beskriver arbetet med att konstruera utrustning för att strimla, tvinna och fixera en flerskiktsfilm i form av reflextejp med avsikten att tillverka garn av den strimlade tejpen där garnet slutligen stickas och vävs till tyger. Avsikten är inte att utveckla reflexgarn eftersom existerande metoder finns för detta, utan att undersöka om garntillverkning från filmmaterial, eller i en förlängning, andra tvådimensionella material lämpar sig för garnproduktion. Om metoden går att utveckla till kostnadseffektiva, industriella processer kan den exempelvis användas för återvinning av textilier i steget innan konsumentnivå. Överproduktion och tyger med fabrikationsfel inom textilindustrin skulle hypotetiskt kunna strimlas till remsor som tvinnas till relativt grova garner i mekaniska processer. En fördel är att materialblandningar och tillsatta additiv som normaltsett försvårar återvinning inte behöver beaktas. Ett annat tänkbart användningsområde är att råvaror som inte är lämpliga till fibertillverkning kan användas förtextilproduktion. Cellulosabaserat material som används till papperstillverkning där papperet sedan strimlas och tvinnas till garner är ett relativt nytt exempel på garnproduktion från tvådimensionell struktur som just nu är under utveckling. De konstruktioner som tillverkades för strimling, tvinning och fixering fungerade för att producera garner som gick att virka, sticka och väva med. En avgörandefaktor för garnkvaliteten var vilken slags polymer som reflextejpens lim var uppbyggd av. Polyuretan visade sig ge det mest användbara garnet och drygt tvåhundrameter garn av detta material tillverkades under arbetet. De processer och metoder som utvecklats är att betrakta som initiala steg, men är uppskalningsbara till kontinuerliga tillverkningsmetoder i industriell produktion. / This report describes the work of designing equipment for shredding, twisting and heat fixate a multilayer film in the form of reflective tape. The intention is to produce yarn of the shredded and twisted tape, where the yarn is finally knitted and woven into fabrics. The intention is not to develop reflex yarns because existing methods exists for this, but to investigate whether yarn production from film materials, or in an extension, other two-dimensional materials are suitable for yarn production. For example, if the method can be developed into cost-effective industrial processes, it can be used for textile recycling in the pre-consumer stage. Overproduction in the textile industry and fabrics with defects could hypothetically be shredded into strips that are twisted into relatively coarse yarns in mechanical processes. One advantage is that material mixtures and additives which normally make recycling difficult need not be taken into account. Another conceivable area of application is that raw materials which are not suitable for fiber production can be used for textile production. Cellulose-based material used for paper where the paper is shredded and twisted into yarns is a relatively new example of yarn production from a two-dimensional structure that is currently under development. The constructions made for shredding, twisting and heat fixation worked to produce yarns that could be transformed into fabrics. A decisive factor for the yarn quality was the kind of polymer on which the tapes adhesive film was made from. Polyurethane was found to provide the most useful yarn and more than two hundred meters of yarn were made from this material during the work. The processes and methods that have been developed are considered initial steps, but are scalable to continuous manufacturing methods in industrial production.