25 resultados para Quadrilateral mesh


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Pelvic floor disorders, such as urinary incontinence (UI) and pelvic organ prolapse (POP), are common disorders in women. Because of the prolonged life expectancy the prevalence of UI and POP and the probability of ending up in surgery are increasing. However, the pathophysiology behind these disorders is still unsolved. The aim of this thesis is to study possible alterations in the connective tissue in the vaginal wall in patients with and without POP. The long-term outcome and complications of mid-urethral slings (MUS) and mesh-augmented POP surgery were studied in heterogenic patient populations. More elastin and a slight increase in immunostaining of type III and V collagens in tissue samples were obtained from patients with POP compared to controls in whom type I collagen was more prominent. The studies assessing the mesh-augmented procedures revealed good efficacy and high patient satisfaction after a long-term follow-up. Patients operated on because of mixed incontinence and with BMI >30 kg/m² reported significantly more urinary symptoms and a lower quality of life than the patients operated on because of stress urinary incontinence and the ones with BMI ≤30 kg/m². The objective outcome was equal between the groups. Mesh exposure through vaginal mucosa occurred in 23 % of the patients after POP surgery, most of these being asymptomatic. There are alterations in connective tissues in patients with POP. Mid-urethral sling procedures produced good long-term cure rates and patient satisfaction. As to the prolapse surgery, in spite of relatively high exposure rate, mesh-augmented procedure proved to be safe and effective method for the correction of POP.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Simplification of highly detailed CAD models is an important step when CAD models are visualized or by other means utilized in augmented reality applications. Without simplification, CAD models may cause severe processing and storage is- sues especially in mobile devices. In addition, simplified models may have other advantages like better visual clarity or improved reliability when used for visual pose tracking. The geometry of CAD models is invariably presented in form of a 3D mesh. In this paper, we survey mesh simplification algorithms in general and focus especially to algorithms that can be used to simplify CAD models. We test some commonly known algorithms with real world CAD data and characterize some new CAD related simplification algorithms that have not been surveyed in previous mesh simplification reviews.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tämän työn tarkoituksena on selvittää, miten höyryn kosteuden erotus toimii Kemijärven Sellun soodakattilassa. Höyryn kosteuden erotuksen toiminta tarkastetaan määrittämällä höyryn kosteus tulistetussa höyryssä. Höyryyn kulkeutuvan kattilaveden määrä määritettiin käyttäen merkkiaineena natriumia, jota kulkeutuu höyryyn kattilavesipisaroiden sekä ruiskutusveden mukana. Pieniä määriä kulkeutuu myös haihtumalla, mikä on otettu laskuissa huomioon. Kattilaveden ja höyryn natriumpitoisuuksien suhteen perusteella lasketaan kosteusprosentti. Kattilaveden kulkeutuessa höyryyn kulkeutuu veden mukana myös epäpuhtauksia, jotka turbiiniin joutuessaan saattavat aiheuttaa korroosiota sekä kerrostumia turbiinin siivistössä. Kosteuden erotuksen parantamiseksi on esitetty muutosehdotus siten, että nykyinen poimulevyerottimilla toteutettu sekundäärierotus korvattaisiin uudella teräsverkkoerottimella. Tällöin pystyttäisiin poistamaan entistä pienempiä pisaroita ja vähentämään höyryyn kulkeutuvan kattilaveden määrää.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This work deals with the cooling of high-speed electric machines, such as motors and generators, through an air gap. It consists of numerical and experimental modelling of gas flow and heat transfer in an annular channel. Velocity and temperature profiles are modelled in the air gap of a high-speed testmachine. Local and mean heat transfer coefficients and total friction coefficients are attained for a smooth rotor-stator combination at a large velocity range. The aim is to solve the heat transfer numerically and experimentally. The FINFLO software, developed at Helsinki University of Technology, has been used in the flow solution, and the commercial IGG and Field view programs for the grid generation and post processing. The annular channel is discretized as a sector mesh. Calculation is performed with constant mass flow rate on six rotational speeds. The effect of turbulence is calculated using three turbulence models. The friction coefficient and velocity factor are attained via total friction power. The first part of experimental section consists of finding the proper sensors and calibrating them in a straight pipe. After preliminary tests, a RdF-sensor is glued on the walls of stator and rotor surfaces. Telemetry is needed to be able to measure the heat transfer coefficients at the rotor. The mean heat transfer coefficients are measured in a test machine on four cooling air mass flow rates at a wide Couette Reynolds number range. The calculated values concerning the friction and heat transfer coefficients are compared with measured and semi-empirical data. Heat is transferred from the hotter stator and rotor surfaces to the coolerair flow in the air gap, not from the rotor to the stator via the air gap, althought the stator temperature is lower than the rotor temperature. The calculatedfriction coefficients fits well with the semi-empirical equations and precedingmeasurements. On constant mass flow rate the rotor heat transfer coefficient attains a saturation point at a higher rotational speed, while the heat transfer coefficient of the stator grows uniformly. The magnitudes of the heat transfer coefficients are almost constant with different turbulence models. The calibrationof sensors in a straight pipe is only an advisory step in the selection process. Telemetry is tested in the pipe conditions and compared to the same measurements with a plain sensor. The magnitudes of the measured data and the data from the semi-empirical equation are higher for the heat transfer coefficients than thenumerical data considered on the velocity range. Friction and heat transfer coefficients are presented in a large velocity range in the report. The goals are reached acceptably using numerical and experimental research. The next challenge is to achieve results for grooved stator-rotor combinations. The work contains also results for an air gap with a grooved stator with 36 slots. The velocity field by the numerical method does not match in every respect the estimated flow mode. The absence of secondary Taylor vortices is evident when using time averagednumerical simulation.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fatigue life assessment of weldedstructures is commonly based on the nominal stress method, but more flexible and accurate methods have been introduced. In general, the assessment accuracy is improved as more localized information about the weld is incorporated. The structural hot spot stress method includes the influence of macro geometric effects and structural discontinuities on the design stress but excludes the local features of the weld. In this thesis, the limitations of the structural hot spot stress method are discussed and a modified structural stress method with improved accuracy is developed and verified for selected welded details. The fatigue life of structures in the as-welded state consists mainly of crack growth from pre-existing cracks or defects. Crack growth rate depends on crack geometry and the stress state on the crack face plane. This means that the stress level and shape of the stress distribution in the assumed crack path governs thetotal fatigue life. In many structural details the stress distribution is similar and adequate fatigue life estimates can be obtained just by adjusting the stress level based on a single stress value, i.e., the structural hot spot stress. There are, however, cases for which the structural stress approach is less appropriate because the stress distribution differs significantly from the more common cases. Plate edge attachments and plates on elastic foundations are some examples of structures with this type of stress distribution. The importance of fillet weld size and weld load variation on the stress distribution is another central topic in this thesis. Structural hot spot stress determination is generally based on a procedure that involves extrapolation of plate surface stresses. Other possibilities for determining the structural hot spot stress is to extrapolate stresses through the thickness at the weld toe or to use Dong's method which includes through-thickness extrapolation at some distance from the weld toe. Both of these latter methods are less sensitive to the FE mesh used. Structural stress based on surface extrapolation is sensitive to the extrapolation points selected and to the FE mesh used near these points. Rules for proper meshing, however, are well defined and not difficult to apply. To improve the accuracy of the traditional structural hot spot stress, a multi-linear stress distribution is introduced. The magnitude of the weld toe stress after linearization is dependent on the weld size, weld load and plate thickness. Simple equations have been derived by comparing assessment results based on the local linear stress distribution and LEFM based calculations. The proposed method is called the modified structural stress method (MSHS) since the structural hot spot stress (SHS) value is corrected using information on weld size andweld load. The correction procedure is verified using fatigue test results found in the literature. Also, a test case was conducted comparing the proposed method with other local fatigue assessment methods.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fluid mixing in mechanically agitated tanks is one of the major unit operations in many industries. Bubbly flows have been of interest among researchers in physics, medicine, chemistry and technology over the centuries. The aim of this thesis is to use advanced numerical methods for simulating microbubble in an aerated mixing tank. Main components of the mixing tank are a cylindrical vessel, a rotating Rushton turbine and the air nozzle. The objective of Computational Fluid Dynamics (CFD) is to predict fluid flow, heat transfer, mass transfer and chemical reactions. The CFD simulations of a turbulent bubbly flow are carried out in a cylindrical mixing tank using large eddy simulation (LES) and volume of fluid (VOF) method. The Rushton turbine induced flow is modeled by using a sliding mesh method. Numerical results are used to describe the bubbly flows in highly complex liquid flow. Some of the experimental works related to turbulent bubbly flow in a mixing tank are briefly reported. Numerical simulations are needed to complete and interpret the results of the experimental work. Information given by numerical simulations has a major role in designing and scaling-up mixing tanks. The results of this work have been reported in the following scientific articles: ·Honkanen M., Koohestany A., Hatunen T., Saarenrinne P., Zamankhan P., Large eddy simulations and PIV experiments of a two-phase air-water mixer, in Proceedings of ASME Fluids Engineering Summer Conference (2005). ·Honkanen M., Koohestany A., Hatunen T., Saarenrinne P., Zamankhan P., Dynamical States of Bubbling in an Aerated Stirring Tank, submitted to J. Computational Physics.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Päällystettyä paperia valmistettaessa syntyy päällystettyä hylkyä, joka kierrätetään takaisin prosessiin raaka-aineen tehokkaaksi hyödyntämiseksi. Hylyn mukana takaisin paperikoneen lyhyeen kiertoon päätyy myös pigmenttiaines levymäisinä partikkeleina. Nämä partikkelit rejektoituvat lyhyen kierron pyörrepuhdistimilla. Raaka-aineen hävikin pienentämiseksi käytetään lyhyessä kierrossa täyteaineen talteenottojärjestelmää, jonka tehtävänä on hienontaa päällystysainepartikkelit tasakokoisiksi, jotta ne voitaisiin palauttaa prosessiin. Talteenottolaitteistojen toiminnan tarkkailun kannalta on keskeistä tietää pyörrepuhdistuslaitoksen eri jakeiden partikkelikokojakaumat juuri pigmenttipartikkelien osalta. Tätä määritystä häiritsee näytteissä oleva kuitu. Tässä työssä pyrittiin löytämään partikkelikokoanalyysimenetelmä, jolla pigmenttien partikkelikokojakauma saataisiin selvitettyä kuidusta huolimatta. Aiemmin käytetty näytteen tuhkaus esikäsittelynä ennen partikkelikokoanalyysiä laserdiffraktiometrillä on osoittautunut toimimattomaksi. Kokeiden pääpaino keskittyi näytteen esikäsittelyyn fraktioinnilla ennen laserdiffraktioanalyysiä ja virtaussytometriamittauksiin. Fraktiointiin käytettiin DDJ-laitetta (dynamic drainage jar), joka oli varustettu metalliviiralla. Kumpikaan menetelmistä ei ollut täysin toimiva partikkelikokoanalyysiin, fraktioinnilla saadaan vähennettyä kuidun partikkelikokojakaumaan aiheuttamaa virhettä, mutta sen toimivuus riippuu paljolti näytteestä. Virtaussytometrialla väriainetta SYTO13 käyttämällä saadaan pigmenttipartikkelit tunnistettua ja näin rajattua kuidut pois mittauksista, mutta pigmenttiä ei saada erotettua puuperäisestä hienoaineesta, mikä vääristää mittaustulosta.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Hoitotieteen pääkokoelma sijaitsee Terveystieteiden osastokirjastossa, jossa painettu yleiskokoelma koostuu 790 nimekkeestä monografioita (painettujen monografiasarjojen osat ovat mukana luvussa). Hoitotiede-kokoelmasta yli 40 % (329 nimekettä) käsittelee käytännön hoitotyötä joko yleisesti (21 % / 168) tai jollakin erityisalueella (20 % /161). Erityisalueista suurimmat ovat geriatrinen hoitotyö (6 % / 42) ja psykiatrinen hoitotyö (4 % 35). Lähes kolmasosa kokoelmasta on yleisteoksia (27 % / 241) käsittäen mm. koulutusta (5 % /41), tutkimusta (11 % /86) ja hoitotyötä ammattina (6 % /51) tarkastelevaa kirjallisuutta. Hoitotyön etiikkaa, filosofiaa ja psykologiaa on kokoelmassa vajaa viidennes (17 % / 137). Hallintoa, esimiestehtäviä ja hoitotyön opetusta käsittelevää kirjallisuutta oli 5 % (43 nimekettä). Hoitotiede on käsikirjaston hyllyluokittelussa osana lääketiedettä. Hoitotieteen alueen nimekkeitä on käsikirjaston kokoelmasta 12 kappaletta, joista pääosa (8 kpl) oli sanakirjoja. Painettuja lehtiä on 8 nimekettä (Hoitotiede, Nursing Clinics of North America, Sairaanhoitaja, Terveydenhoitaja, Pro Terveys, Vård i Norden, Tutkiva hoitotyö, Spirium). Sähkökirjoja kokoelmassa on noin 50 nimekettä Ebrary-tietokannassa, 2 nimekettä NetLibrary-tietokannassa ja 2 nimekettä Taylor & Francis eBooks online -tietokannassa ja sähköisiä terveystieteen sanastoja 5 kpl (Hoidokki – hoitotyön asiasanasto, FinMeSH-asiasanasto, Medical Subject Headings (MeSH), Sosiaali- ja terveydenhuollon sanastoja (STAKES) ja Swedish MeSH). Verkkolehtiä kokoelmassa on noin 230 nimekettä (ISI Web of Knowledge Journal Citation Reports -tietokannan listaamista 36 nimekkeestä kokoelmissa on 86 % (31 nimekettä). Tietokantoja on 33, mm. lehtitietokanta Ebscohost Academic Search Premier ja viitetietokantoja mm. British Nursing Index, CINAHL (Ovid), EBM Reviews: Cochrane Database of Systematic Reviews, Medic, Medline (Ovid)ja PsycINFO (Ebsco).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Kansanterveystieteen pääkokoelma sijaitsee Terveystieteiden osastokirjastossa, jossa painettu yleiskokoelma koostuu 970 nimekkeestä monografioita (painettujen monografiasarjojen osat mukana luvussa). Kansanterveystieteen kokoelmasta 18 % (175) käsittelee tilastoja; näistä teoria- ja menetelmäkirjallisuutta on noin 13 % (122). Yleisteoksien osuus kokoelmasta on vajaa 14 % (130). Muita kokoelman keskeisiä alueita ovat mm. työterveys (12 % / 117), terveydenhuollon hallinto (13 % / 125), eri väestöryhmien terveysongelmat (8 % / 81), terveyskasvatus (9 % / 84) sekä sosiaalilääketiede (4 % / 44). Kansanterveystiede on käsikirjaston hyllyluokittelussa osana lääketiedettä. Kansanterveystieteen nimekkeitä on käsikirjaston kokoelmasta 17 kappaletta, joista pääosa sanakirjoja (8 kpl) ja tilastoja (6 kpl). Painettuja lehtiä on 8 nimekettä (Environment and Health, Journal of Public Mental Health, Kansanterveys, Promo: Terveyden edistämisen lehti, Scandinavian Journal of Work, Salud publica de Mexico, Työ ja ihminen, Työ terveys turvallisuus). Sähkökirjoja kokoelmassa on noin 450 nimekettä Ebrary-tietokannassa, Netlibraryssa 8 nimekettä ja Taylor & Francis –tietokannassa 1 nimeke ja elektronisia sanastoja 4 (FinMESH, Medical Subject Headings (MeSH), Sosiaali- ja terveydenhuollon sanastoja (STAKES), Swedish MeSH). Verkkolehtiä kokoelmassa on 400 nimekettä, joista 35 % vapaasti käytettävissä verkossa. ISI Web of Knowledge Journal Citation Reports –tietokannan listaamista alan keskeisistä 98 nimekkeestä kokoelmissa on 78 % (76 nimekettä). Lehdistä, joiden IF-arvo on suurempi kuin 2, oli kokoelmissa 88 % (30 / 34). IF -välillä 1-1.99 vastaava luku oli 84 % (32 / 38) ja välillä 0–0.99 54 % (14 / 26). Tietokantoja on 36; mm. lehtitietokanta ScienceDirect ja viitetietokantoja mm. EBM Reviews: Cochrane Database of Systematic Reviews, LEO, Medic, Medline (Ovid), Science Citation Index Expanded (ISI), Social Sciences Citation Index (ISI), Tyki.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Gerontologian ja geriatrian pääkokoelma sijaitsee Terveystieteiden osastokirjastossa, jossa painettu yleiskokoelma koostuu 251 nimekkeestä monografioita. Kokoelmassa on runsaasti (38 %) sosiaaligerontologian kirjallisuutta, jolloin vanhenemisesta tarkastellaan yhteiskunnallisesta näkökulmasta. Kokoelmasta noin viidennes (22 %) on vanhenemiseen liittyviä yleisteoksia. Vanhenemista prosessina (13 %) ja geriatrista psykiatriaa (12 %) käsittelevät kirjat ovat myös selvästi edustettuina. Painettuja edelleen tulevia lehtiä on 3 kpl (Gerontechnology, Gerontologia, International Journal of Aging and Human Development). Sähkökirjoja on noin 150 nimekettä Ebrary-tietokannassa ja noin 40 nimekettä SpringerLink-tietokannassa. Lisäksi Books@Ovid, MDConcult ja Oxford Medical Handook Online -kokoelmissa yksi kirja. Tietosanakirjoja on 1 kpl (Encyclopedia of Gerontology). Sanastoja on 5 kpl( Hoidokki, Medical Subject Headings (MeSH), Sosiaali- ja terveydenhuollon sanasto, Swedish MeSH, Termix). Verkkolehtiä on kokoelmassa noin 80 nimekettä. ISI Web of Knowledge Journal Citation Reports -tietokannan listaamista 52 gerontologian & geriatrian lehdistä kokoelmissa on 38 nimekettä eli 73 prosenttia. Gerontologiaan ja geriatriaan liittyviä artikkeleita löytyy usean tieteenalan, kuten lääketieteen, hoitotieteen, kansanterveystieteen ja sosiaalitietieteiden, viitetietokannoista. Tietokantoja on noin 15-20, joista keskeisimpiä ovat esimerkiksi Medline, Web of Science ja Cinahl. Tämän lisäksi käytössä on useita lehtitietokantoja, esimerkiksi ScienceDirect ja EbscoHost.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

As technology geometries have shrunk to the deep submicron regime, the communication delay and power consumption of global interconnections in high performance Multi- Processor Systems-on-Chip (MPSoCs) are becoming a major bottleneck. The Network-on- Chip (NoC) architecture paradigm, based on a modular packet-switched mechanism, can address many of the on-chip communication issues such as performance limitations of long interconnects and integration of large number of Processing Elements (PEs) on a chip. The choice of routing protocol and NoC structure can have a significant impact on performance and power consumption in on-chip networks. In addition, building a high performance, area and energy efficient on-chip network for multicore architectures requires a novel on-chip router allowing a larger network to be integrated on a single die with reduced power consumption. On top of that, network interfaces are employed to decouple computation resources from communication resources, to provide the synchronization between them, and to achieve backward compatibility with existing IP cores. Three adaptive routing algorithms are presented as a part of this thesis. The first presented routing protocol is a congestion-aware adaptive routing algorithm for 2D mesh NoCs which does not support multicast (one-to-many) traffic while the other two protocols are adaptive routing models supporting both unicast (one-to-one) and multicast traffic. A streamlined on-chip router architecture is also presented for avoiding congested areas in 2D mesh NoCs via employing efficient input and output selection. The output selection utilizes an adaptive routing algorithm based on the congestion condition of neighboring routers while the input selection allows packets to be serviced from each input port according to its congestion level. Moreover, in order to increase memory parallelism and bring compatibility with existing IP cores in network-based multiprocessor architectures, adaptive network interface architectures are presented to use multiple SDRAMs which can be accessed simultaneously. In addition, a smart memory controller is integrated in the adaptive network interface to improve the memory utilization and reduce both memory and network latencies. Three Dimensional Integrated Circuits (3D ICs) have been emerging as a viable candidate to achieve better performance and package density as compared to traditional 2D ICs. In addition, combining the benefits of 3D IC and NoC schemes provides a significant performance gain for 3D architectures. In recent years, inter-layer communication across multiple stacked layers (vertical channel) has attracted a lot of interest. In this thesis, a novel adaptive pipeline bus structure is proposed for inter-layer communication to improve the performance by reducing the delay and complexity of traditional bus arbitration. In addition, two mesh-based topologies for 3D architectures are also introduced to mitigate the inter-layer footprint and power dissipation on each layer with a small performance penalty.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This thesis presents a three-dimensional, semi-empirical, steady state model for simulating the combustion, gasification, and formation of emissions in circulating fluidized bed (CFB) processes. In a large-scale CFB furnace, the local feeding of fuel, air, and other input materials, as well as the limited mixing rate of different reactants produce inhomogeneous process conditions. To simulate the real conditions, the furnace should be modelled three-dimensionally or the three-dimensional effects should be taken into account. The only available methods for simulating the large CFB furnaces three-dimensionally are semi-empirical models, which apply a relatively coarse calculation mesh and a combination of fundamental conservation equations, theoretical models and empirical correlations. The number of such models is extremely small. The main objective of this work was to achieve a model which can be applied to calculating industrial scale CFB boilers and which can simulate all the essential sub-phenomena: fluid dynamics, reactions, the attrition of particles, and heat transfer. The core of the work was to develop the model frame and the required sub-models for determining the combustion and sorbent reactions. The objective was reached, and the developed model was successfully used for studying various industrial scale CFB boilers combusting different types of fuel. The model for sorbent reactions, which includes the main reactions for calcitic limestones, was applied for studying the new possible phenomena occurring in the oxygen-fired combustion. The presented combustion and sorbent models and principles can be utilized in other model approaches as well, including other empirical and semi-empirical model approaches, and CFD based simulations. The main achievement is the overall model frame which can be utilized for the further development and testing of new sub-models and theories, and for concentrating the knowledge gathered from the experimental work carried out at bench scale, pilot scale and industrial scale apparatus, and from the computational work performed by other modelling methods.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This thesis presents an approach for formulating and validating a space averaged drag model for coarse mesh simulations of gas-solid flows in fluidized beds using the two-fluid model. Proper modeling for fluid dynamics is central in understanding any industrial multiphase flow. The gas-solid flows in fluidized beds are heterogeneous and usually simulated with the Eulerian description of phases. Such a description requires the usage of fine meshes and small time steps for the proper prediction of its hydrodynamics. Such constraint on the mesh and time step size results in a large number of control volumes and long computational times which are unaffordable for simulations of large scale fluidized beds. If proper closure models are not included, coarse mesh simulations for fluidized beds do not give reasonable results. The coarse mesh simulation fails to resolve the mesoscale structures and results in uniform solids concentration profiles. For a circulating fluidized bed riser, such predicted profiles result in a higher drag force between the gas and solid phase and also overestimated solids mass flux at the outlet. Thus, there is a need to formulate the closure correlations which can accurately predict the hydrodynamics using coarse meshes. This thesis uses the space averaging modeling approach in the formulation of closure models for coarse mesh simulations of the gas-solid flow in fluidized beds using Geldart group B particles. In the analysis of formulating the closure correlation for space averaged drag model, the main parameters for the modeling were found to be the averaging size, solid volume fraction, and distance from the wall. The closure model for the gas-solid drag force was formulated and validated for coarse mesh simulations of the riser, which showed the verification of this modeling approach. Coarse mesh simulations using the corrected drag model resulted in lowered values of solids mass flux. Such an approach is a promising tool in the formulation of appropriate closure models which can be used in coarse mesh simulations of large scale fluidized beds.