<p>The increasing demand for higher performance in rocketlaunchers promotes the development of nozzles with higherperformance, which basically is achieved by increasing theexpansion ratio. However, this may lead to flow separation andensuing instationary, asymmetric forces, so-called side-loads,which may present life-limiting constraints on both the nozzleitself and other engine components. Substantial gains can bemade in the engine performance if this problem can be overcome,and hence different methods of separation control have beensuggested. However, none has so far been implemented in fullscale, due to the uncertainties involved in modeling andpredicting the flow phenomena involved.</p><p>In the present work the causes of unsteady and unsymmetricalflow separation and resulting side-loads in rocket enginenozzles are investigated. This involves the use of acombination of analytical, numerical and experimental methods,which all are presented in the thesis. A main part of the workis based on sub-scale testing of model nozzles operated withair. Hence, aspects on how to design sub-scale models that areable to capture the relevant physics of full-scale rocketengine nozzles are highlighted. Scaling laws like thosepresented in here are indispensable for extracting side-loadcorrelations from sub-scale tests and applying them tofull-scale nozzles.</p><p>Three main types of side-load mechanisms have been observedin the test campaigns, due to: (i) intermittent and randompressure fluctuations, (ii) transition in separation patternand (iii) aeroelastic coupling. All these three types aredescribed and exemplified by test results together withanalysis. A comprehensive, up-to-date review of supersonic flowseparation and side-loads in internal nozzle flows is givenwith an in-depth discussion of different approaches forpredicting the phenomena. This includes methods for predictingshock-induced separation, models for predicting side-loadlevels and aeroelastic coupling effects. Examples are presentedto illustrate the status of various methods, and theiradvantages and shortcomings are discussed.</p><p>A major part of the thesis focus on the fundamentalshock-wave turbulent boundary layer interaction (SWTBLI) and aphysical description of the phenomenon is given. Thisdescription is based on theoretical concepts, computationalresults and experimental observation, where, however, emphasisis placed on the rocket-engineering perspective. This workconnects the industrial development of rocket engine nozzles tothe fundamental research of the SWTBLI phenomenon and shows howthese research results can be utilized in real applications.The thesis is concluded with remarks on active and passive flowcontrol in rocket nozzles and directions of futureresearch.</p><p>The present work was performed at VAC's Space PropulsionDivision within the framework of European spacecooperation.</p><p><b>Keywords:</b>turbulent, boundary layer, shock wave,interaction, overexpanded,rocket nozzle, flow separation,control, side-load, experiments, models, review.</p>

Elasto-plastic shock waves in high-velocity compaction of spherical metal particles are the focus of this thesis which consists of four papers (A-D). The compaction process is modeled by a discrete element method while using elastic and plastic loading, elastic unloading and adhesion at contacts. Paper A investigates the dynamic compaction of a one-dimensional chain of homogenous particles. The development of the elasto-plastic shock waves, its propagation and influence on the compaction process are examined. Simulations yield information on the contact behavior, velocity of the particle and its deformation during dynamic compaction. Effects of changing loading parameters on the compaction process are also discussed. Paper B addresses the non-homogeneity in a chain having; particles of different sizes and materials, voids between the particles and particles with/without adhesion between them. Simulations show transmission and reflection of elasto-plastic shock wave during compaction process. The particle deformation during incident and reflected shocks and particle velocity fluctuations due to voids between particles are simulated. The effects of adhesion on particles separation during unloading stage are also discussed. Paper C develops a simulation model for a high-velocity compaction process with auxiliary pistons, known as relaxation assists, in a compaction assembly. The simulation results reveals that the relaxation assists offer; smooth compaction during loading stage, prevention of  the particle separation during unloading stage and conversion of  higher kinetic energy of hammer into particles deformation.  Furthermore, the influence of various loading elements on compaction process is investigates. These results support the findings of experimental work. Paper D further extends the one-dimensional case of Paper A and B into two-dimensional assembly of particles while adding friction between particles and between particles and container walls. Three particular cases are investigated including closely packed hexagonal, loosely packed random and a non-homogenous assembly of particles of various sizes and materials. Consistent with the one-dimensional case, primary interest is the linking of particle deformation with the elasto-plastic shock wave propagation. Simulations yield information on particle deformation during shock propagation and change in overall particles compaction with the velocity of the hammer. The force exerted by particles on the container walls and rearrangement of the loosely packed particles during dynamic loading are also investigated. Finally, the effects of presence of friction and adhesion on both overall particles deformation and compaction process are simulated. / QC 20110311

Ischemic heart disease (IHD) is one of leading morbidity and mortality caused worldwide. Along with medical treatment currently there are two main methods of coronary revascularisation – percutaneous coronary intervention (PCI) and aortocoronary bypass surgery (ACBS). New heart revascularisation methods are under development, which are to be applied for routine practice in the future. One of methods stimulating angiogenesis is cardiac shock wave therapy (CSWT). CSWT is new reconstructive / regeneration treatment method offering alternative for revascularisation, as use of steam cells for such purposes is still in the stage of trials. Low frequency mechanical waves are used for CSWT. Their effect results in improved heart perfusion and development of blood vessels' network. Such waves for the first time in medicine were applied about 20 years ago for renal stones fragmentation. This treatment method has been recently applied in clinics worldwide and only few of them obtained some experience in this area. CSWT, along with medical and invasive treatment methods for patients with severely advanced ischemic heart disease, in Santariškių Clinics of Vilnius University Hospital was introduced in 2008. / MSBT– tai naujas atkuriamojo/ regeneracinio gydymo būdas, galintis tapti revaskuliarizacijos alternatyva, nes kamieninių ląstelių pritaikymas tokiais tikslais tebėra tiriamas. MSBT metu naudojamos žemo dažnio mechaninės bangos, kurioms veikiant, pagerinama širdies perfuzija ir sukuriamas kraujagyslių tinklas. Tokios bangos pirmą kartą medicinoje buvo pritaikytos inkstų akmenims skaldyti maždaug prieš 20 metų . MSBT tyrimai pradėti atlikti su pacientais, kuriems diagnozuota labai pažengusi išeminė širdies liga, lydima III−IV klasės krūtinės anginos(KA) pagal Kanados klasifikaciją (CCS), yra trijų vainikinių arterijų liga, kartais su kairės vainikinės arterijos kamieno stenoze. Šiems pacientams anksčiau atliktos angioplastikos ir stentavimo procedūros arba viena ar kelios aortokoronarinių jungčių suformavimo operacijos, tačiau KA atsinaujino, todėl nuolatos skiriamos maksimalios toleruojamos nitratų dozės. Tačiau krūtinės anginos epizodai kartojasi kelis kartus per dieną minimalaus fizinio krūvio metu ar net ramybėje. Pasaulyje šis gydymo metodas tik pradedamas taikyti ir pirminės patirties sukaupta tik nedaugelyje klinikų. Iki 2008m. VUL Santariškių klinikose išemine širdies liga (IŠL) sergantys pacientai buvo gydomi standartiniais metodais: medikamentais, PKI ir vainikinių arterijų apeinamųjų jungčių suformavimo operacija. 2008 m. Vilniaus universiteto ligoninės Santariškių klinikose labai pažengusia išemine širdies liga sergančių pacientų gydymui, be medikamentinio ir... [toliau žr. visą tekstą]

MSBT– tai naujas atkuriamojo/ regeneracinio gydymo būdas, galintis tapti revaskuliarizacijos alternatyva, nes kamieninių ląstelių pritaikymas tokiais tikslais tebėra tiriamas. MSBT metu naudojamos žemo dažnio mechaninės bangos, kurioms veikiant, pagerinama širdies perfuzija ir sukuriamas kraujagyslių tinklas. Tokios bangos pirmą kartą medicinoje buvo pritaikytos inkstų akmenims skaldyti maždaug prieš 20 metų . MSBT tyrimai pradėti atlikti su pacientais, kuriems diagnozuota labai pažengusi išeminė širdies liga, lydima III−IV klasės krūtinės anginos(KA) pagal Kanados klasifikaciją (CCS), yra trijų vainikinių arterijų liga, kartais su kairės vainikinės arterijos kamieno stenoze. Šiems pacientams anksčiau atliktos angioplastikos ir stentavimo procedūros arba viena ar kelios aortokoronarinių jungčių suformavimo operacijos, tačiau KA atsinaujino, todėl nuolatos skiriamos maksimalios toleruojamos nitratų dozės. Tačiau krūtinės anginos epizodai kartojasi kelis kartus per dieną minimalaus fizinio krūvio metu ar net ramybėje. Pasaulyje šis gydymo metodas tik pradedamas taikyti ir pirminės patirties sukaupta tik nedaugelyje klinikų. Iki 2008m. VUL Santariškių klinikose išemine širdies liga (IŠL) sergantys pacientai buvo gydomi standartiniais metodais: medikamentais, PKI ir vainikinių arterijų apeinamųjų jungčių suformavimo operacija. 2008 m. Vilniaus universiteto ligoninės Santariškių klinikose labai pažengusia išemine širdies liga sergančių pacientų gydymui, be medikamentinio ir... [toliau žr. visą tekstą] / Ischemic heart disease (IHD) is one of leading morbidity and mortality caused worldwide. Along with medical treatment currently there are two main methods of coronary revascularisation – percutaneous coronary intervention (PCI) and aortocoronary bypass surgery (ACBS). New heart revascularisation methods are under development, which are to be applied for routine practice in the future. One of methods stimulating angiogenesis is cardiac shock wave therapy (CSWT). CSWT is new reconstructive / regeneration treatment method offering alternative for revascularisation, as use of steam cells for such purposes is still in the stage of trials. Low frequency mechanical waves are used for CSWT. Their effect results in improved heart perfusion and development of blood vessels' network. Such waves for the first time in medicine were applied about 20 years ago for renal stones fragmentation. This treatment method has been recently applied in clinics worldwide and only few of them obtained some experience in this area. CSWT, along with medical and invasive treatment methods for patients with severely advanced ischemic heart disease, in Santariškių Clinics of Vilnius University Hospital was introduced in 2008.

Introdução: A terapia com ondas de choque tem sido proposta como forma de tratamento para doença de Peyronie, mesmo não se conhecendo exatamente qual o mecanismo de ação das ondas de choque na placa fibrótica desta doença. A principal hipótese postulada para o mecanismo de ação é a neovascularização estimulada pelas ondas de choque, com conseqüente liberação de óxido nítrico e diminuição dos fatores inflamatórios através da ação dos macrófagos. Alguns estudos em humanos mostraram resultados favoráveis na melhora da dor peniana e do desempenho sexual após utilização da terapia com ondas de choque, no entanto até o momento não existe nenhum trabalho demonstrando a existência de lesões no tecido peniano adjacente à placa fibrótica, ou até mesmo se há formação de novas placas. Objetivo: O objetivo deste estudo é determinar a existência de lesões estruturais teciduais no pênis de coelhos, após a utilização da terapia com ondas de choque. Métodos: Para o estudo foram utilizados vinte e cinco coelhos machos adultos da linhagem New Zeeland White, divididos em três grupos: Grupo I: Controle - Composto por cinco animais, que foram submetidos a três sessões de ondas de choque, com dois mil disparos cada, de intensidade de 15 KV; neste grupo, foi colocada uma placa protetora de borracha entre o equipamento de litotripsia e o pênis. Os animais foram sacrificados sete dias após a última sessão. Grupo II: Tratado com avaliação precoce - Composto por dez animais que foram submetidos a três sessões de ondas de choque, com dois mil disparos, de intensidade de 15 KV, diretamente sobre o pênis. Os animais foram sacrificados após sete dias da última sessão. Grupo III: Tratado com avaliação tardia - Composto por dez animais que foram submetidos a três sessões de ondas de choque, com dois mil disparos, de intensidade de 15 KV, diretamente sobre o pênis. Os animais foram sacrificados noventa dias após a última sessão para análise histológica e morfométrica. Resultados: Macroscopicamente foram observados hematomas, petéquias e equimoses em 100% e uretrorragia em 57,9% dos animais dos grupos tratados, sintomas esses que regrediram após 48 horas. Microscopicamente foram observadas lesões como degeneração da camada basal somente no grupo tratado com avaliação precoce em 55,6%, papilomatose e acantose nos dois grupos tratados em 22,2%, congestão da derme em 100% dos animais do grupo tratado com avaliação precoce e 80% dos animais do grupo tratado com avaliação tardia e espessamento da túnica albugínea em 80% dos animais do grupo tratado com avaliação tardia. A histomorfometria da túnica albugínea mostrou média de 16,6% de fibras de colágeno no grupo controle, 20,9% no tratado com avaliação precoce e 49,1% no tratado com avaliação tardia (p<0,001) causando desorganização e remodelamento da túnica. Não houve diferença estatística na porcentagem de fibras musculares nos corpos cavernosos entre os grupos, sendo a média no grupo controle de 54,6%, no grupo tratado com avaliação precoce de 56,1% e no grupo tratado com avaliação tardia de 47,8% (p=0,214). Conclusão: A terapia com ondas de choque é um método que produz lesões teciduais em todos os planos do pênis com aumento da quantidade das fibras de colágeno na túnica albugínea e provocando assim um remodelamento e desorganização da túnica albugínea / Introduction: Extracorporeal shockwaves (ESWL) have been proposed as a treatment for Peyronie\'s disease. Objective: The aim of this study is to determine whether there is any injury to the normal penile tissue during ESWL in rabbits. Methods: 25 adult male NZW rabbits undergone to 3 sessions of ESWL . Divided into 3 groups: Group I(no shock) - 5 animals. Group II(Short-term effect) - 10 animals, sacrificed 7 days. Group III(Long-term effect) - 10 animals evaluated 90 days after the last session. The penile tissue was analyzed. Results: Macroscopically was observed the presence of hematomas, petechias and equimosis. Histological evaluation demonstrated the presence of basal cell degeneration, papilomathosis, acanthosis, congestion and fibrosis of the albuginea with increase of collagen fibers. Conclusion: ESWL produce injury in all tissues of the penis

Les mousses liquides sont utilisées dans de nombreux domaines de la vie quotidienne. Leur excellente capacité à dissiper de l'énergie en fait également des matériaux très utilisés dans le domaine militaire pour atténuer les ondes de souffle émises lors d'une explosion. Dans cette thèse, nous avons conçu un dispositif expérimental original nous permettant de visualiser la déformation d'une mousse liquide lors de l'impact d'une onde de souffle en sortie d'un tube à choc. Nous mesurons la surpression en plusieurs points de la mousse, sur une gamme de 5 à 50 kPa. Nous mettons en évidence une atténuation de pression qui augmente avec la taille des bulles puis sature, tous les autres paramètres, notamment la fraction liquide, étant maintenus constants. Ces résultats sont interprétés avec un modèle de dissipation thermique à l'échelle de la bulle suggérant l'existence d'un maximum d'atténuation pour une taille de bulles donnée. Nous caractérisons ensuite la vitesse de propagation de l'onde au sein de la mousse. Aux petites amplitudes, la vitesse suit le modèle de Wood, basé sur une propagation linéaire dans un milieu continu effectif. Aux plus hautes amplitudes, nous mettons en évidence l'apparition d'un régime non linéaire, avec une vitesse de propagation plus importante et une atténuation plus faible, ces deux phénomènes étant retrouvés à la fois théoriquement et numériquement. Près de la source, la mousse est détruite par le choc. Nous terminons notre étude avec des résultats plus qualitatifs sur la quantité de mousse détruite et la vitesse de propagation du front de rupture, visualisées pour la première fois dans une mousse tridimensionnelle. / Liquid foams are used in various domains in our everyday life. Their excellent ability to dissipate energy makes foams widely used in the military domain to mitigate blast waves produced after an explosion. In this Thesis, we have designed an original experimental setup allowing us to image the deformation of a liquid foam after the impact of a blast wave exiting a shock tube. We also measure the overpressure in the foam, within a range of 5 to 50\,kPa. We evidence a pressure attenuation, increasing and then saturating at increasing bubble size, while all the other parameters of the foam, especially liquid fraction, are kept constant. Those results are interpreted with a thermal dissipation model at the bubble scale, suggesting the existence of a maximum dissipation for a given bubble size. We then characterise the wave velocity in the foam. At small amplitudes, the velocity follows Wood's model, based on linear propagation in an effective continuous medium. At greater amplitudes, we show the apparition of a non-linear regime, with a higher propagation velocity and a lower attenuation, those two features being captured theoretically and numerically. Close to the source, the foam is destroyed by the shock. We close our study with more qualitative results on the quantity of destroyed foam and the propagation velocity of the rupture front, which have been evidenced for the first time in a three-dimensional foam.

Historically, the endeavor of scale testing flight vehicles at supersonic Mach numbers, especially for long durations, has required the development of closed-loop wind tunnels, which are extremely expensive both to build and operate due to the high complexity and incredible power required to drive such a system. The intermittent blowdown wind tunnel, indraft tunnel, and shock tunnel have alleviated many of these cost requirements to some degree, whilst facilitating testing at very high Mach numbers and enthalpies; however, these systems require the handling of gases at pressures and temperatures that can be prohibitive for many university settings. The Ludwieg tube provides a simple, elegant method for producing testable supersonic flows at price points significantly lower than the aforementioned test-system architectures. Unfortunately, the spacial footprint and moderate cost required for driver tube and nozzle hardware can make it difficult to implement for many non-research universities. In this thesis, a new supersonic test system architecture is conceived, designed, implemented, and validated for the purpose of making supersonic aerodynamic testing capability attainable for most universities, by combining properties of the Ludwieg Tube and indraft wind tunnel to reduce the cost needed to produce this capability. This system, the Indraft Tube Tunnel, requires no long driver-tube or test-section hardware, aside from a vacuum chamber. Furthermore, it is safe to operate, as high pressure containment systems are not required for the Indraft Tube Tunnel System. It is designed and operated to draw stagnant atmospheric air through a converging-diverging nozzle to achieve a steady-state Mach number of 2.5. Sufficient pressure ratio to reach the desired Mach number is attained by evacuating the vacuum chamber and placing a thin cellophane diaphragm across the inlet of the nozzle, thus separating the vacuum section from ambient atmosphere. To initiate gas flow, the diaphragm is mechanically burst with a puncture device. This design requires much less hardware to implement than a typical Ludwieg tube, and had an operating cost of less than one dollar per test. Using this method, steady, uninterrupted Mach 2.44 is attained for a duration of 13.6 ms and a test section diameter of 7 inches. The standard deviation of the Mach number measurements is .08 Mach. A shadowgraph imaging setup is used to view and measure the angle of oblique shockwaves on a simple wedge test-model. The Indraft Tube Tunnel is novel in the field of high-speed aerodynamic testing, and may be implemented by other universities to produce supersonic flows with a relatively small investment in hardware and laboratory space.

The compressible turbulent boundary layer developing over atwo-dimensional bump which leads to a supersonic pocket with aterminating shock wave has been studied. The measurements havebeen made with hot-wire anemometry and Particle ImageVelocimetry (PIV). A method to calibrate hot-wire probes in compressible ow hasbeen developed which take into account not only the ow velocitybut also the inuence of the Mach number, stagnation temperatureand uid density. The calibration unit consists of a small jetow facility, where the temperature can be varied. The hot wiresare calibrated in the potential core of the free jet. The jetemanates in a container where the static pressure can becontrolled, and thereby the gas density. The calibration methodwas verfied in the at plate zero pressure gradient turbulentboundary layer in front of the bump at three different Machnumbers, namely 0.3, 0.5 and 0.7. The profiles were alsomeasured at different static pressures in order to see theinuence of varying density. Good agreement between the profilesmeasured at different pressures, as well as with the standardlogarithmic profile was obtained. The PIV measurements of the boundary layer ow in front ofthe 2D bump showed good agreement with the velocity profilesmeasured with hotwire anemometry. The shock wave boundary layerinteraction was investigated for an inlet Mach number of 0.69.A lambda shock wave was seen on the downstream side of thebump. The velocity on both sides of the shock wave as measuredwith the PIV was in good agreement with theory. The shock wavewas found to cause boundary layer separation, which was seen asa rapid growth of the boundary layer thickness downstream theshock. However, no back ow was seen in the PIV-data, probablybecause the seeding did not give enough particles in theseparated region. The PIV data also showed that the shock wavewas oscillating, i.e. it was moving approximately 5 mm back andforth. This distance corresponds to about five boundary layerthicknesses in terms of the boundary layer upstream theshock. <b>Descriptors:</b>Fluid mechanics, compressible ow,turbulence, boundary layer, hot-wire anemometry, PIV, shockwave boundary layer interaction, shape factor. / NR 20140805

NR 20140805

Background: Spasticity is a common symptom post-stroke which causes vast complications regarding important daily functions among patients. This manifests as a resistance in the muscle during a velocity-dependent passive motion and is commonly evaluated by using the Modified Ashworth Scale (MAS). Extra corporeal shock wave therapy (ESWT) is a relatively novel way to treat spasticity, with promising results. Purpose: The aim of the current study was to investigate the scientific evidence of ESWT as treatment regarding spasticity and function among patients with prolonged stroke. Methods: The purpose was tackled by conducting a literature review of randomized controlled trials with MAS as outcome measurement. PubMed was searched for relevant studies followed by a quality assessment through the PEDro Scale. The reliability of the evidence was assessed with the use of GRADEstud.  Results: The quality of the included articles was mainly deemed as good with eight of nine articles receiving a PEDro Score of 6 or higher. This review found generally positive effects from ESWT regarding spasticity with MAS as the outcome measurement. The results regarding function were equivocal. The reliability of the results was graded as very low due to the methodological heterogeneity of the included studies. Conclusion: ESWT showed positive results regarding spasticity and function, although the reliability of the evidence was considered very low. More research is inquired to further explore the potential effects of ESWT on spasticity and function among post-stroke patients. This could potentially increase the reliability of the evidence regarding ESWT as a treatment option. / Bakgrund: Spasticitet är ett vanligt förekommande funktionsnedsättande centralt symptom bland patienter med stroke och har tendens att öka med tiden efter insjuknandet. Spasticitet manifesteras i form av ett ökat muskelmotstånd vid hastighetsberoende passivt rörelseuttag och bedöms oftast med Modified Ashworth Scale (MAS). Stötvågsterapi (ESWT) är en relativt ny behandlingsmetod och visats ha en lovande effekt mot spasticitet.   Syfte: Syftet med arbetet har varit att undersöka det vetenskapliga underlaget för ESWT som behandling för spasticitet och funktion hos individer med långvarig stroke. Metod: Arbetets syfte har angripits genom en systematisk narrativ litteraturstudie. Sökning av relevanta studier gjordes i databasen PubMed och skulle uteslutande vara randomiserade kontrollerade studier med MAS som utfallsmått. Studierna utvärderades gällande risk för snedvridning genom PEDro Scale. Tillförlitligheten i evidensen av effekterna av ESWT har bedömts med GRADEstud.  Resultat: Arbetets urval bedömdes ha låg risk för snedvridning då åtta av nio artiklar fick ≥ 6 poäng på PEDro Scale. ESWT sågs övergripligt ha positiva effekter på spasticitet mätt med MAS, både som isolerad och kombinerad behandling. Gällande funktion var resultaten mer tvetydiga. Dock bedömdes tillförlitligheten gällande evidensen för effekterna som mycket låg pga. genomlöpande heterogenitet bland studierna gällande design och urval.   Slutsatser: Övergripligt visade ESWT-behandling ha en positiv effekt på spasticitet och funktion. Tillförlitligheten i evidensen bedömdes dock som mycket låg. Mer forskning efterfrågas i att belysa effekterna av ESWT på patienter med stroke för att uppnå högre tillförlitlighet.