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1
Rogers, D. „An examination of bubble dynamics and double metastability within an improved glass Berthelot tube“. Thesis, Swansea University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638705.
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This thesis presents the developmental, practical and theoretical aspects of an improved Berthelot tube apparatus used to investigate cavitation phenomena in deionised water. Values of the breaking tension of deionised water in the range of 2.5 bar to 30 bar are herein reported for experiments in the improved apparatus and the obtained breaking tensions are certainly comparable to those previously reported for experiments carried out using both the Berthelot tube technique and other methods. Herein dynamic pressure records and high-speed photographic images of cavitation occurring in deionised water are reported, for what is believed to be the first time. The initial formation, growth and collapse of cavitation bubbles are compared to the dynamic pressures existing in the tube using analytical methods to process the high-speed images and dynamic pressure traces. The growth/collapse cycles of bubbles associated with cavitation in the improved apparatus are shown to be an order of magnitude higher than those occurring in bullet-piston experiments (a typical cycle taking about 240 μs in the improved Berthelot tube), and the corresponding velocity of the initial growth of the cavity is reported to be in the order of 21 m/s. In Chapter 6 high-speed images of the formation of ice in deionised water under double metastable conditions are reported for the first time. In these experiments it was shown that it was possible for deionised water in a double metastable phase to be cooled to -18°C before ice suddenly started to form, at a specific point, and rapidly propagated throughout the water at a much greater rate (upwards of 25 cm/s) than would otherwise be predicted for the formation of ice under ‘free’ conditions, suggesting that some additional factor was involved in the ice formation. Several proposals have been put forward in an attempt to explain the mechanism behind the ice formation.
2
Koen, Johan Alexander. „An investigation into the axial capacity of eccentrically loaded concrete filled double skin tube columns“. Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96797.
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Thesis (MSc)--Stellenbosch University, 2015.ENGLISH ABSTRACT: Concrete filled double skin tube (CFDST) columns is a new method of column construction. CFDST columns consists of two steel hollow sections, one inside the other, concentrically aligned. The cross-sections of the two hollow sections does not have to be the same shape. Concrete is cast in between the two hollow sections resulting in a CFDST. This study only considers CFDST columns constructed with circular steel hollow sections. The advantages of CFDST construction include: ● The inner and outer steel hollow sections replaces the traditional steel reinforcement that would be used in a normal reinforced concrete column. This reduces the construction time since there is no need to construct a reinforcing cage. ● The steel hollow sections acts as a stay in place formwork, eliminating the need for traditional formwork. This also reduces construction time. ● The steel hollow sections confine the concrete, making it more ductile and increasing its yield strength. The objective of this study is to identify methods that can predict the axial capacity of eccentrically loaded circular CFDST columns. Methods chosen for the investigation are: 1. Finite element model (FEM). A model was developed to predict the behaviour of eccentrically loaded CFDST columns. The FE model uses a concrete material model proposed in literature for stub columns. The aim was to determine whether the material model is suited for this application. 2. The failure load of CFDST columns under concentric loading was calculated using a model obtained in literature. These capacities were compared to the experimental test results of eccentrically loaded CFDST columns to establish a correlation. This study found that the concrete material model used does not adequately capture the behaviour resulting in the axial response of the column being too stiff. The difference between the eccentrically loaded experimental test results and the calculated concentrically loaded capacity showed a clear trend that could be used to predict the capacity of eccentrically loaded CFDST columns.
AFRIKAANSE OPSOMMING: Beton-gevulde dubbel laag pyp (BGDLP) kolomme is ‘n nuwe metode van kolom konstruksie. BGDLP kolomme bestaan uit twee staal pyp snitte, die een binne die ander geplaas met hul middelpunte opgelyn, die dwarssnit van die twee pype hoef nie dieselfde vorm te wees nie. Beton word dan in die wand tussen die twee pyp snitte gegiet. Die resultaat is ‘n hol beton snit. Hierdie studie handel slegs oor BGDLP kolomme wat met ronde pyp snitte verwaardig is. Die volgende voordele kan aan BGDLP toegeken word: ● Die binne en buite staalpype vervang die tradisionele staal bewapening was in normale bewapende-beton gebruik sou word. Dus verminder dit die tyd wat dit sal neem om die kolom op te rig. ● Die staalpypsnitte is ook permanente vormwerk. Dit doen dus weg met die gebruik van normale bekisting, wat ook konstruksie tyd spaar. ● Die buite-staalpypsnit bekamp die uitsetting van die beton onder las. Hierdie bekamping veroorsaak dat die beton se gedrag meer daktiel is en ‘n hoër falings spanning kan bereik. Die doel van die studie is om metodes te identifiseer wat gebruik kan word om die aksiale kapasiteit onder eksentriese laste van BGDLP kolomme te bepaal. Twee metodes was gekies: 1. Eindige element model. ‘n Model was ontwikkel om die gedrag van BGDLP kolomme te voorspel. Die mikpunt was om te bepaal of ‘n beton materiaal gedrag model vanuit die literatuur gebruik kan word om BGDLP kolomme te modelleer. 2. Die swiglas van BGDLP kolomme onder konsentriese belasting was bereken vanaf vergelykings uit die literatuur. Hierdie swiglaste was vergelyk met die eksperimentele toets resultate vir eksentriese belaste BGDLP kolomme om ‘n korrelasie te vind. Hierdie studie het bewys dat die beton materiaal model uit die literatuur kan nie gebruik word om die swiglaste van BGDLP kolomme te bepaal nie. Die model het die gedrag te styf gemodelleer. Die verskil tussen die berekende konsentriese belaste swiglas en die eksperimentele resultate van eksentriese BGDLP kolomme was voorspelbaar en kan gebruik word om die swiglas van eksentriese belaste BGDLP kolomme te voorspel.
3
Sharma, Priyanka. „Identification d’un double rôle de l’E3-Ubiquitine ligase Mindbomb au cours de la morphogénèse du tube neural du poisson zèbre“. Thesis, Nice, 2015. http://www.theses.fr/2015NICE4069/document.
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Au cours de ce projet de thèse, j’ai étudié le lien fonctionnel entre la morphogénèse épithéliale et la signalisation Delta-Notch, dans le cadre de la formation du tube neural chez le poisson-zèbre. La signalisation Delta-Notch est primordiale pour le développement embryonnaire et le maintien de l’homéostasie des tissus adultes. De façon inattendue, j’ai observé suite à la perte-de-fonction de Mib une perte de la polarité apico-basale dans le neuro-épithélium de la moelle épinière embryonnaire. L’analyse plus poussée de ce phénotype m’a ensuite permis de montrer que l’activité de l’intégralité de la signalisation Notch est requise pour l’établissement de la polarité apico-basale dans le tube neural de poisson-zèbre. En effet, l’inhibition des ligands de Notch et des activateurs transcriptionnels situés en aval, Rbpja et Rbpjb, résulte en l’interruption de la polarité apico-basale. De plus, l’activation ectopique de Notch entraîne un sauvetage complet de la polarité apico-basale dans les embryons déplétés pour Mib. Finalement, le mutant Mib échoue à activer la transcription de protéines de polarité apicale Crumbs1 et Crumbs2a au cours de la formation du tube neural, ce qui suggèrerait que la signalisation Notch agit en amont des complexes de polarité. De façon surprenante, nous avons également montré que le composant de la signalisation Notch, Mib, affecte les mouvements de convergence-extension et la division cellulaire orientée, appelée C-divisions, durant la neurulation et la gastrulation à travers la signalisation PCP. Cet effet de Mib sur la PCP est indépendant de son rôle sur la signalisation Notch. Généralement, cette étude révèle un double-rôle de MibIn this Ph.D. project, I study the functional link between epithelial polarity and Delta-Notch signaling in the context of zebrafish neural tube morphogenesis. Notch signaling, one of the major signaling pathways and of prime importance in neurogenesis, has been widely studied for its function in cell fate specifications. Surprisingly, I found that the Notch signaling component Mindbomb (Mib) loss-of-function led to a loss of apico-basal polarity in the neuroepithelium of the embryonic spinal cord. I further explored that the activity of the entire Notch signaling pathway is actually required for the earliest steps of establishment of apico-basal polarity in the zebrafish neural tube. Indeed, inhibition of Notch ligands and downstream transcriptional activators Rbpja and Rbpjb resulted in a disruption of apico-basal polarity. Moreover, ectopic activation of Notch ensued to a complete rescue of apico-basal polarity in Mib loss of function embryos. Furthermore, Mib mutant embryos fail to upregulate the transcription of the apical polarity proteins Crumbs1 and Crumbs2a in the course of neural tube formation, suggesting that Notch signalling might act upstream of polarity complexes. Moreover, I found that Mib affects convergent-extension movements and oriented cell divisions during neurulation and gastrulation through an effect on planar cell polarity. Remarkably, this effect of Mib on PCP is independent of its role in Notch signaling. These results indicate a novel role of Mib in the regulation of PCP signaling. Altogether, this study revealed a dual role of Mib in the epithelial morphogenesis of the zebrafish neural tube
4
Zhao, H., R. Wang, Dennis Lam, C.-C. Hou und R. Zhang. „Behaviours of circular CFDST with stainless steel external tube: Slender columns and beams“. Elsevier, 2020. http://hdl.handle.net/10454/18141.
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NoIn this work, experimental and numerical investigations were performed on the behaviours of circular concrete filled double steel tubular (CFDST) slender columns and beams, in which the external tube employed stainless steel tube. Eighteen specimens, 12 slender columns and 6 beams, were tested to obtain the failure patterns, load versus deflection relationships and strain developments of stainless steel tube. A finite element (FE) model was developed and verified by experimental results. The validated FE model was then employed to investigate the effects of key parameters, including hollow ratio, eccentric ratio and material strength, on the load-carrying capacity. The load distribution among the components and contact stress between steel tube and sandwiched concrete were also analyzed. Finally, the design methods for CFDST, hollow CFST and solid CFST members with carbon steel external tube respectively suggested by Han et al. (2018), Chinese GB 50936-2014 (2014) and AISC 360-16 (2016) were employed to evaluate their applicability for the circular CFDST slender columns and beams with stainless steel outer tube.
The authors gratefully acknowledge the Shanxi Province Outstanding Youth Fund (No. 201701D211006) and the National Natural Science Foundation (No. 51838008).
The full-text of this article will be released for public view at the end of the publisher embargo on 9th Nov 2021.
5
Yamamoto, Yasumichi. „Intrathoracic esophageal replacement in the dog using a collagen sponge-silicone double layer tube as an artificial esophagus“. Kyoto University, 1999. http://hdl.handle.net/2433/181244.
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6
Gebert, Marina. „The gametophyte specific ARM repeat protein AtARO1 is required for actin dynamics in Arabidopsis during pollen tube growth and double fertilization“. kostenfrei, 2008. http://www.opus-bayern.de/uni-regensburg/volltexte/2008/1072/.
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7
Barrios, Godoy Miguel Alejandro. „Validation of the Fung double tube to enumerate Clostridium perfringens from the intestinal contents of broiler chickens raised on different diets“. Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/13759.
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Master of ScienceDepartment of Animal Science
R. Scott Beyer
Daniel Y.C. Fung
Clostridium perfringens causes necrotic enteritis (NE), resulting in decreased feed efficiency and increased mortality, costing the poultry industry USD 2 billion a year worldwide. The objective of the first trial was to validate the Fung Double Tube (FDT) to detect and enumerate C. perfringens in chicken intestines. Two methods (FDT and petri plates) and three media (Shahidi Ferguson Perfringens [SFP] with egg supplement, polymyxin B [p], and kanamycin [k; E]; SFP with p and k [P]; and SFP with cycloserine [C]) were arranged in a 2 x 3 factorial, resulting in six treatments. The FDT with medium C (5.35 log CFU/g) had significantly (P<0.05) higher C. perfringens counts than any other media/method combination. The objective of the second and third trials was to determine the effect of diet type on the population of C. perfringens in broiler intestines using the FDT. Trial 2 tested: corn-soybean meal (SBM), low-crude protein (19.8%)/high synthetic amino acids (SAA), and barley (56%)-fishmeal (4%; BF). Diets in Trial 3 included: corn-SBM, barley (7.46%), fishmeal (4%), and BF. Diets in Trial 2 contained an antibiotic and a coccidiostat; diets in Trial 3 did not. After 21 days, birds in Trial 2 fed BF had significantly higher (P<0.05) counts (5.96 log CFU/g) of C. perfringens, as compared to all other diets. Both, corn-SBM and SAA diets resulted in 3.89 log CFU/g. In Trial 3, birds fed the corn-SBM diet (2.7 log CFU/g) had significantly lower (P<0.05) counts than broilers fed BF (4.15 log CFU/g). When broilers were fed fishmeal (3.583 log CFU/g) and barley (3.577 log CFU/g) separately, C. perfringens counts were numerically higher compared to the corn-SBM diet, but numerically lower than birds fed BF. Barley and fishmeal inclusion increased the incidence of C. perfringens, and their combination resulted in a cumulative effect. The FDT method is able to detect C. perfringens at higher levels than the conventional petri plate method (P<0.001) and it also proved to be an effective method to detect differences in C. perfringens counts from the intestines of chickens fed different diet.
8
Mutelle, Hervé. „Modelisation de l'ecoulement et de la thermique double phase a l'interieur d'un tube droit de generateur de vapeur once-through a surchauffe chauffe au sodium“. Nantes, 1997. http://www.theses.fr/1997NANT2113.
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Pour les futurs reacteurs nucleaires a neutrons rapides, il est prevu d'utiliser des generateurs de vapeur composes de tubes droits. Compte tenu de la structure hyperstatique de ce type de composant, il est necessaire lors de la phase de dimensionnement de disposer d'un outil numerique fiable avec des modeles d'echange thermique et de perte de charge adaptes a toute la plage de fonctionnement de l'appareil. Ce memoire porte sur l'etude et sur le choix de ces modeles physiques. Notre analyse s'est faite a partir de donnees experimentales obtenues sur une maquette monotubulaire a l'echelle une et a l'aide d'un logiciel de simulation developpe dans le cadre de cette these. On montre que, quelles que soient les correlations utilisees, l'accord calcul-mesure se degrade d'autant plus que le niveau de puissance est faible. L'instrumentation utilisee nous a permis egalement d'obtenir des informations interessantes sur la geometrie de la zone d'assechement et sur les fluctuations de temperature induites par ce phenomene. On montre, en particulier, que les frequences principales se situent en-deca de 3 hertz. A partir de thermocouples implantes en sortie de la maquette, nous avons egalement constate l'existence d'un desequilibre thermique entre phases en ecoulement vapeur-gouttes, y compris a pression elevee. De plus, plusieurs elements suggerent que les gouttes se deplacent par paquets.
9
Ghyoot, Christiaan Jacob. „The modelling of particle build up in shell-and-tube heat exchangers due to process cooling water / Christiaan Jacob Ghyoot“. Thesis, North-West University, 2013. http://hdl.handle.net/10394/9511.
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Sasol Limited experiences extremely high particulate fouling rates inside shell-and-tube heat
exchangers that utilize process cooling water. The water and foulants are obtained from
various natural and process sources and have irregular fluid properties. The fouling
eventually obstructs flow on the shell side of the heat exchanger to such an extent that the
tube bundles have to be replaced every nine months. Sasol requested that certain aspects
of this issue be addressed.
To better understand the problem, the effects of various tube and baffle configurations on
the sedimentation rate in a shell-and-tube heat exchanger were numerically investigated.
Single-segmental, double-segmental and disc-and-doughnut baffle configurations, in
combination with square and rotated triangular tube configurations, were simulated by using
the CFD software package, STAR-CCM+. In total, six configurations were investigated.
The solution methodology was divided into two parts.
Firstly, steady-state solutions of the six configurations were used to identify the best
performing model in terms of large areas with high velocity flow. The results identified both
single-segmental baffle configurations to have the best performance.
Secondly, transient multiphase simulations were conducted to investigate the sedimentation
characteristics of the two single-segmental baffle configurations. It was established that the
current state of available technology cannot adequately solve the detailed simulations in a
reasonable amount of time and results could only be obtained for a time period of a few
seconds.
By simulating the flow fields for various geometries in steady-state conditions, many of the
observations and findings of literature were verified. The single-segmental baffle
configurations have higher pressure drops than double-segmental and disc-and-doughnut
configurations. In similar fashion, the rotated triangular tube configuration has a higher
pressure drop than the square arrangement. The single-segmental configurations have on
average higher flow velocities and reduced cross-flow mass flow fractions. It was concluded
from this study that the single-segmental baffle with rotated triangular tube configuration had
the best steady-state performance.
Some results were extracted from the transient multiphase simulations. The transient
multiphase flow simulation of the single-segmental baffle configurations showed larger
concentrations of stagnant sediment for the rotated triangular tube configuration versus
larger concentrations of suspended/flowing sediment in the square tube configuration. This
result was offset by the observation that the downstream movement of sediment was quicker
for the rotated triangular tube configuration.
No definitive results could be obtained, but from the available results, it can be concluded
that the configuration currently implemented at Sasol is best suited to handle sedimentation.
This needs to be verified in future studies by using advanced computational resources and
experimental results.Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013
10
Van, Wayenbergh Réginald. „Recherche de partenaires protéiques du facteur de transcription HRT1 par la technique du double hybride: identification de BOIP, nouvel ADNc codant une protéine interagissant avec le domaine Orange de HRT1“. Doctoral thesis, Universite Libre de Bruxelles, 2004. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211120.
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Un nouveau facteur de transcription, appartenant à la famille des protéines à domaine bHLH, a récemment été isolé dans notre laboratoire. Initialement appelé « clone bc8 » puis HRT1, ce facteur présentait des similitudes avec les protéines Hairy and Enhancer of split qui interviennent notamment dans le phénomène d’inhibition latérale lors de la formation du tissu neural. Des études d’hybridation in situ réalisées chez l'embryon de xénope ont suggéré un rôle important de XHRT1, la protéine HRT1 de xénope, dans le développement neural. Nous avons recherché les partenaires protéiques de XHRT1 par la technique du double-hybride afin de mieux comprendre son mécanisme d’action moléculaire dans la neurogenèse.Tout d’abord nous avons construit les outils appropriés pour l’élaboration du travail, à savoir, les clones de levures exprimant les appâts spécifiques des domaines de la protéine étudiée et la création d’une banque d’ADNc du xénope au stade de la neurulation. Ensuite, trois criblages ont été réalisés. Dans le premier cas, nous avons recherché les partenaires des domaines bHLH et Orange (bHLH-O). Le domaine bHLH est en effet responsable de la dimérisation de ce type de protéine. Le domaine Orange qui suit le domaine bHLH, pourrait participer dans le choix du partenaire d’hétérodimérisation. Nous avons isolé deux facteurs de type bHLH-Orange apparentés à HRT1, XHairy1 et XHairy2b et confirmé leur interaction avec XHRT1. Les domaines impliqués dans ces interactions sont les bHLH-O pour les trois facteurs. Ce même criblage nous a permis d’isoler un nouvel ADNc qui code une protéine sans domaine apparent connu actuellement. Nous avons montré que cette protéine reconnaissait spécifiquement le domaine Orange de HRT1 mais pas celui des autres facteurs de type bHLH-O. Elle a été baptisée BOIP pour Bc8 Orange Interacting Protein. Le rôle physiologique de cette interaction n’a pu être démontré. Nous avons établi que la protéine BOIP pouvait aussi s’homodimériser. Nous avons aussi déterminé son profil d’expression chez le xénope et la souris. Son transcrit est hautement présent dans les testicules adultes. La protéine pourrait donc jouer un rôle important dans la spermatogenèse. Les deux autres criblages, utilisant les domaines situés dans la partie C-terminale de XHRT1, ont apporté des nouveaux partenaires potentiels, mais ces interactions n’ont pu être confirmées dans un système indépendant.
Enfin, en étudiant plus en détail les interactions entre XHRT1 et XHairy1 ou XHairy2b, nous avons mis à jour une possible fonction de spécificité dans le choix du partenaire dans la région C-terminale de HRT1. La formation de ces dimères pourrait jouer un rôle dans la formation du tube neural mais également dans d’autres différenciations tissulaires.
Doctorat en sciences, Spécialisation biologie moléculaire
info:eu-repo/semantics/nonPublished
11
Havlů, Michal. „Algoritmus automatického výběru vhodného typu zařízení z databáze výměníků tepla“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228730.
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Thesis is devoted to development of an database algorithm for selection (or necking selection) of suitable type of heat exchanger for given industrial application. Database creates a part of multipurpose calculation system containing three individual modules: (i) module for selection (or necking selection) of type of heat exchanger for given application, (ii) module for thermal-hydraulic design or rating of heat exchanger, (iii) module for calculation of investments and operating cost. Thesis describes details of method for selection of suitable heat exchanger type for given application and presents and discuss individual criteria for selection process which influence values in tables of priorites for given equipment. These tables are unavoible part of selection algorithm. Details of software application of selection algorithm are also presented in the thesis. Description of behaviour of individual types of heat exchanger creates important part of thesis. Practical application of developed selection algorithm is demonstrated on several industrial examples.
12
Alahmad, Malik I. N. „Heat transfer in upward flowing two-phase gas-liquid mixtures : an experimental study of heat transfer in two-phase gas-liquid mixtures flowing upwards in a vertical tube with liquid phase being driven by a pump or air injection“. Thesis, University of Bradford, 1987. http://hdl.handle.net/10454/3629.
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An experimental investigation has been carried out to study the heat transfer in a two-phase two-component mixture flowing upward inside a 1" double pipe heat exchanger. The heat transfer coefficient was measured using either air to lift the liquid (air-lift system) or a mechanical pump. The heat transfer coefficient results have been extensively studied and compared with other workers' results. An attempt was made to correlate the present heat transfer data in dimensionless correlations. Possible factors affecting the two-phase heat transfer coefficient have been studied with special attention being given to the fluid properties, particularly the liquid viscosity. Experiments were also carried out to investigate the effect of solid particles added to a liquid flow on the measured heat transfer coefficient. The present investigation was carried out using air as the gas-phase ranging from 2x 10-5 up to 80 x 10-5 m3/s. Liquids used were water and glycerol solutions with viscosity ranging from 0.75 up to 5.0 C. P. and flowrates between 4x 10-5 and 25 x 10-5 m3/s. Void fraction and pressure drop were also measured during the heat transfer process. Flow pattern in gas-liquid mixture was investigated in a perspex tube of identical dimensions to the heat exchanger tube.
13
Korytář, Jan. „Aspekty ovlivňující trendy v technologii provozu letadlové techniky civilního letectví“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443765.
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The aim of the work is a general description of the effects on air traffic and aircraft. The first part of the work is devoted to a brief description of the development of individual technical parameters and performance of aircraft from the 1920s to the present with an assessment of the effects. The second part of the work is about the influence of current requirements and the third part is a general view of the future development of construction and technology for more economical and environmentally friendly air transport
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Mohamed-Meziani, Slimane. „Etude dynamique et thermique des écoulements en simple et double phase dans des tubes corrugués“. Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37608085h.
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Guinoiseau, Françoise Gelas Bruno. „Figures du Double et de la métamorphose de E. T. A. Hoffmann à Francis Bacon tude de sémiologie textuelle /“. [S.l.] : [s.n.], 1999. http://demeter.univ-lyon2.fr:8080/sdx/theses/lyon2/2000/fguinoiseau.
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Labbi, Mohammed Larbi. „Courbure riemannienne: variations sur différentes notions de positivité“. Habilitation à diriger des recherches, Université Montpellier II - Sciences et Techniques du Languedoc, 2006. http://tel.archives-ouvertes.fr/tel-00267987.
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On étudie différentes notions de courbure riemanniennes: la $p$-courbure, qui interpole entre courbure scalaire et courbure sectionnelle, les courbures de Gauss-Bonnet-Weyl qui constituent une autre interpolation allant de la courbure scalaire jusqu'à l'intégrand de Gauss-Bonnet.
Les $(p,q)$-courbures que nous dégageons englobent toutes ces notions. On examine ensuite le terme en courbure de la formule classique de Weitzenböck. On étudie aussi les propriétés de positivité de la $p$-courbure, la seconde courbure de Gauss-Bonnet-Weyl, la courbure d'Einstein et de la courbure isotrope.
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Castillo, Mercedes Liliana Prieto. „Ensaios de arrancamento e cisalhamento em descontinuidades simuladas reforçadas com barras de aço“. Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-25042012-111830/.
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Ancoragens são muito utilizadas na estabilização do maciço rochoso pela rapidez e baixo custo, embora sua análise não seja completamente entendida devido à interação de diferentes materiais como rocha, graute e aço. Este documento apresenta os resultados de um estudo realizado em juntas lisas reforçadas com ancoragens. Foram ensaiadas ancoragens com barras de diferentes diâmetros e diferentes orientações em relação ao plano da descontinuidade. Os ensaios realizados para avaliar o comportamento deste tipo de reforço foram o ensaio de arrancamento em tubo duplo e o ensaio de cisalhamento em juntas lisas reforçadas. Os ensaios de arrancamento em tubo duplo demonstraram que a resistência ao arrancamento é dependente da resistência à tração da barra. As deformações internas no sistema foram idealizadas através da obtenção de um comprimento livre hipotético de uma barra livre submetida a tração. Nos ensaios de cisalhamento, avaliou-se a melhora da resistência ao cisalhamento de descontinuidades lisas reforçadas com barras ancoradas. Observaram-se dois picos de carga mobilizada antes da ruptura do sistema no caso de barras perpendiculares ao plano da descontinuidade. Este fato introduz significativa ductilidade ao sistema e é importante do ponto de vista de confiabilidade do sistema. A ruptura das ancoragens se produz devido a uma combinação de efeitos de tração, flexão, e cortantes. Os sistemas reforçados com áreas maiores de aço apresentaram maior ductilidade, e, portanto oferecem maior segurança. Os resultados sugerem que uma vez superado o comprimento mínimo ancorado a ruptura das ancoragens acontecerá por ruptura das barras de aço e não por aderência na interface barra-graute, concluindo-se que a resistência das ancoragens é dependente da resistência de ruptura e da área de aço utilizada. Finalmente, esta pesquisa contribui ao entendimento dos mecanismos de ruína que acontecem num maciço reforçado com ancoragens.Rock anchors are widely used to stabilize rock masses due to their rapid installation and low cost. Their behavior is not fully understood because of the interaction of different elements such as rock, grout and steel. This document presents the results of both pull-out and shear tests on steel bar reinforced discontinuities. Tests were carried out with different diameters and orientations of bars with respect to the discontinuity plane. Double-pipe pullout tests and smooth-joint anchor-reinforced shear tests were performed. The results of double-pipe pull-out tests were analyzed in terms of both strength and deformations. Internal strains were idealized through a model based on hypothetical length of a free bar. In the smooth-joint anchor-reinforced shear tests, both increase in shear strength and ductility were evaluated. Two load peaks were observed in test with bars perpendicular to the joint plane. Ductility is significantly increased with respect to joints reinforced with inclined bars. This is important for reliability evaluation. The failure of anchors is produced by a combination of tensile, bending, and shear internal forces. The systems reinforced with a greater amount of steel presented more ductile behavior than those less reinforced. The results suggest that since the minimum anchor length is exceeded, the system failure is governed by the rebar failure and not by the adhesion in the rebar-grout interface. From this, it is concluded that the anchor strength is dependent on the strength and cross section area of the rebar. Finally, this research contributes to better understanding of the failure mechanisms of anchor-reinforced rock masses.
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Winder, Brian Geoffrey. „Achieving Complex Motion with Fundamental Components for Lamina Emergent Mechanisms“. Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2279.pdf.
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Champagne, Antoine. „Diversité chimique et biofortification des plantes à racines et tubercules tropicales cultivées : caractérisation des parents et élaboration de protocoles permettant l'optimisation de la sélection“. Thesis, Saint-Etienne, 2010. http://www.theses.fr/2010STET4017.
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L’agrobiodiversité s'étudie au niveau génotypique mais également au niveau de l'expression chimique de ce génotype, le chimiotype. Les plantes à racines et tubercules tropicales (manioc, patate douce, ignames et taros) sont multipliées par voie asexuée et les bases génétiques sont bien souvent étroites chez les cultivars traditionnels. Malgré les faibles diversités génétiques révélées à l'aide de marqueurs ADN, les chimiotypes sont très variables et leur étude est riche d’informations. Ces cultures vivrières, plantes amylacées mais aussi sources de molécules intéressantes pour les industries alimentaire et pharmaceutique, tiennent un rôle déterminant dans la garantie de la sécurité alimentaire des pays du Sud. Dans cette optique, leur amélioration génétique par voie conventionnelle est une contribution majeure aux enjeux actuels. De nombreux efforts restent néanmoins à réaliser pour analyser, compiler et disséminer les informations liées à la diversité des compositions et teneurs de plantes qui restent sous-utilisées ou non appréciées à leur juste valeur. La biofortification qui vise une amélioration des propriétés nutritionnelles de ces plantes, présente de nombreux avantages dont le principal est de ne pas modifier les comportements alimentaires tout en permettant une meilleure adaptation environnementale des nouveaux génotypes. Leur amélioration passe par une sélection des parents basée sur leurs valeurs propres et le criblage de grands nombres d'individus hybrides. Le processus est long et fastidieux. L’élaboration de nouveaux outils permettant une optimisation de cette tâche est donc nécessaire. L'analyse d'échantillons représentatifs de la variabilité chimiotypique des collections du Vanouatou, un archipel Mélanésien abritant une riche agrobiodiversité, a permis d'étudier les relations entre composés majeurs, métabolites secondaire et préférences alimentaires locales. Les corrélations mises en évidence permettent d'apporter des éléments utiles à la compréhension du processus de sélection traditionnelle. L’identification des préférences visées par ce processus aident à comprendre les goûts et les attentes des consommateurs, et donc à mieux définir les idéotypes ciblés par les programmes d'amélioration. Ce travail a permis un premier criblage chimiotypique d'un grand nombre de cultivars appartenant aux deux espèces majeures, le taro (Colocasia esculenta) et la grande igname (Dioscorea alata). L'étude des caroténoïdes et des anthocyanes a permis d’identifier un certain nombre de cultivars comme parents potentiellement intéressants pour la biofortification mais aussi pour l'exploitation commerciale directe des clones. La caractérisation des hybrides, obtenus par panmixie et pollinisations libres au cours de cycles de sélection récurrente, indique que des gains importants sont obtenus pour des composés et métabolites essentiels. Les avancées réalisées dans le cadre de ce travail, et leurs conséquences pour les programmes d'amélioration génétique en cours, sont discutées. Les perspectives de mise au point de nouveaux outils de criblage et de nouvelles méthodes de caractérisation qui permettront in fine une meilleure approche de la biofortification de ces cultures vivrières, sont aussi envisagéesAgronomic selection generates and maintains agrobiodiversity which can be regarded as an essential resource. To describe phenotypic diversity, genotypes as well as their chemical expression, chemotypes, have been widely used. Tropical root and tuber crops are vegetatively propagated and their genetic bases are often narrow. Therefore, unveiling the impressive phenotypic diversity is still rather difficult through genotyping alone, whereas chemotype studies are very informative. Tropical root crops are staples and represent a good source of compounds related to health benefits and used in food and pharmaceutical industries. Those crops have key-roles to play in food security for developing countries and so plant breeding cannot be neglected. Biofortification is effective and does not imply change of dietary behaviours. Analysing, computing and compiling data bases for chemical data on diversity of neglected crops are still needed. Biofortification involving mass selection and profiling of numerous accessions is, however, time-consuming. Thus, efficient protocols and tools facilitating this process are required. Chemotypic variability within Vanuatu germplasm was characterised through core samples from different species and relationships between primary compounds, secondary metetabolites and local preferences have been studied. Useful correlations were shown, thus clarifying traditional selection process. This process has permitted the definition of ideotypes that will be interesting for the management of breeding programmes. At least for the two most important species in Vanuatu - taro Colocasia esculenta and the greater yam - Dioscorea alata -our work is the first broad screening of germplasm. The study of carotenoid and anthocyanin content indicates that some cultivars show potential for commercial exploitation. With the aim of improving staple foods by plant breeding, we identified accessions to be selected as parents for future crosses
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Huang, Min-Yi, und 黃閔邑. „Ground Settlement Due to Double-O-Tube Shield Tunneling“. Thesis, 2011. http://ndltd.ncl.edu.tw/handle/38116014119249312015.
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碩士國立交通大學
土木工程學系
100
Based on the construction of Taoyuan International Airport Access MRT with the Double-O-Tube (DOT) shield tunneling method, this thesis studies ground settlement due to tunneling. Based on the field data, the hyperbolic model is proposed to simulate the settlement-time relationship due to DOT shield tunneling. Peck(1969) suggested that the surface settlement due to shield tunneling can be decribed with a normal distribution curve. Based on the field data, measured at 11 different cases in 3 different countries, this study analyzes the settlement trough width parameter i and maximum surface settlement Smax due to DOT shield tunneling. Based on this study, the following conclusions are made. 1. Field data indicated that the maximum rolling angle was 0.38∘, which was less than the limiting design rolling angle of 0.6∘. As the rolling angle became greater than the management value of 0.2∘, action would be taken. The measures adopted by the contractor to correct the rolling angle included: reverse rotation of the cutter disc, backfill grouting, and overcut of ground with the copy cutter. 2. In the departure section, the estimated speed of DOT excavation was 2.0 m/day. The measured speed of excavation was 2.5 m/day, which was 25 % faster than the estimated speed. In the normal excavation section, the estimated speed of excavation was 4.3 m/day, and the measured speed was 4.55 m/day, which was 5.8 % faster than the estimated speed. In the arrival section, the estimated speed of excavation was 2.0 m/day, and the measured speed was 4.3 m/day, which was 115 % faster than the estimated speed. 3. The estimated total duration for DOT shield tunneling was 400 days. The actual excavation duration was 360 days, which was 10 % shorter than the estimated duration. 4. The ground loss due to DOT shield tunneling varied form 0.21 to 1.34 %, and the average ground loss was 0.85 %. 5. Field monitored data indicated that the settlement-time relationship induced by DOT shield tunneling can be properly described by the hyperbolic model. 6. Field monitored settlement data indicated that the settlement trough monitored in the field was in fairly good agreement with the normal distribution estimation proposed by peck.
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Weng, Chung-Hsin, und 翁崇興. „Cyclic Responses of Double-Tube Unbonded Brace Elements and Connections“. Thesis, 2002. http://ndltd.ncl.edu.tw/handle/78408223195938500017.
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碩士國立臺灣大學
土木工程學研究所
90
In recent years, a number of researches have confirmed that the buckling restrained braced frame (BRBF) is an effective system for severe seismic application. Buckling restrained bracing (BRB) members can be conveniently made from several kinds of structural steel shape encased in steel tube and confined by infill concrete. When the brace is subjected to compressions, an unbond material placed between the core bracing and the concrete infill is required in order to reduce the friction while restrain the bracing from buckling. In order to reduce the length and the number of bolts in the brace-to-gusset connection, the double-tee double-tube (DTDT) unbonded braces have been developed and extensively tested in National Taiwan University in the past few years. The objectives of this research include: 1) further investigating the effectiveness of various types of unbond material, 2) developing guidelines for the design of the restrain tubes as well the tie elements connecting the two tubes, 3) constructing the constant cyclic axial strain versus fatigues cycle or strain energy relationships for the A36 unbonded braces, and 4) providing guidelines for the design of bolted joint for the brace-to-gusset connections. In this research, a total of ten unbonded braces employing single tube and flat core steel plate details were fabricated and tested cyclically in order to investigate the effectiveness of various kind of unbond material. It is confirmed that the 2-mm thick silicon rubber sheet is most effective in minimizing the variations of peak brace compressive and tensile responses. Test results also suggest that a strain hardening factor of at 1.5 and 1.4 should be considered for the analysis and design of the unbonded braces employing A36 and A572 Grade 50 steels, respectively. Additional ten double-plate double-tube (DPDT) unbonded braces using A36 material for the core element, 2-mm thick silicon rubber sheet for the unbond material were fabricated and tested by applying first cyclically increasing then constant fatiguing strains. Test results also confirm that strain hardening factor can be as high as 1.8 when the steel core peak tensile strain reaches 0.02. Tests confirmed that the proposed strength and stiffness requirements developed for the tie elements between the two tubes can be conveniently applied in the design and construction of the double tubed unbonded braces subjected to large inelastic strain reversals. Test results also confirm that the constant cyclic axial strain versus fatigues cycle or strain energy relationships can be satisfactorily predicted by the log-log linear empirical relationships developed from regression analysis of the fatigue test data. Finally, six DPDT brace to gusset connection specimens incorporating two different levels of roughness at the contacting surface were tested. A set of cyclically increasing forces and displacements was applied to find out the slip load of the bolted joints. Then, two additional sets of similar cyclically increasing forces and displacements but reduced in magnitude subsequently were applied to confirm the cyclically degrading of the slip capacity. This research presents the responses of the bolts and the stiffeners at the brace-to-gusset joints and concludes with the design recommendations for the brace end connections.
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Chang, Yu-Ting, und 張寓婷. „Numerical Analysis with Robust Design in Double-Tube Tunnel Construction“. Thesis, 2015. http://ndltd.ncl.edu.tw/handle/88718105030872445409.
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碩士國立中興大學
土木工程學系所
103
Soil is a material with variable material properties. In the engineering analysis, if we could take into account the uncertainties of those material properties, the design results will more closely match the real behavior. By considering the uncertainties, we can not only make appropriate designs, but also reduce the cost. In other words, the engineering project can be both secure and economic. This study aims to explore the robust design of a double-tube tunnel. Because of the uncertainties of soil parameters, the cost could be very different for the cross tunnels and the main tunnels. To understand which design factor is more sensitive is essential to improve our design such as the strength of soil, the length of cross tunnel, the supporting system, etc. This study adopted the Phase2v8.0, a two-dimensional finite element analysis software to investigate double-tube tunnels. Different uncertainties of control factors with different length of cross tunnel were analyzed to find the probability of failure. The probability of failure is obtained by a Monte Carlo type of analyses to find the ratio of cases with strength factor less than one at the boundaries of main tubes. The study of double-tube tunnels was focused on Taichung city and Taipei city in the study. The results suggest that the standard deviation of random variables, horizontal stress ratio, and length of cross tunnel play important roles in standard deviation of probability of failure. The standard deviation of random sampling and the standard deviation of probability of failure is inversely correlated. The horizontal stress ratio is also inversely correlated with the standard deviation of probability of failure, no matter the ratio is assigned or from the empirical formula of friction angle. In addition, the length of cross tunnel is inversely correlated with the standard deviation of probability of failure. Finally, the study also investigate the best designs by the optimize analyses. The optimize analysis is to find the cases with the smallest standard deviation of probability of failure and the lowest cost. The results suggest that the best design options also possess the minimum horizontal stress ratio and the maximum of the standard deviation of random sampling.
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Fu, Chia-Chun, und 傅家俊. „Process Analysis and Roll Design for Double Radius Tube Roll Forming“. Thesis, 2015. http://ndltd.ncl.edu.tw/handle/597pd7.
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碩士國立高雄應用科技大學
模具工程系
103
Seamed tubes are widely used for fossil industrials (transportation of gas and petroleum), hardware (door, windows, and railing), transportation (vehicle structures), and building (structure component). The seamed tubes are made usually using cold roll forming process which suffers the defects of edge wavy, surface scratching, and the welding line variation. This research is focused on the welding line variation of a cold-roll-formed tube considering different designs of process and die. Taguchi method was adopted to obtain optimum design of the cold roll forming process and die design. The process design was carried out considering the roll forming pass and the roll flower designs. The calculation method of the sheet blank width and the distribution of the bend angles of each pass were proposed. Theoretical radius of tube at each stand were calculated and controlled carefully to create the roll flower of tube roll forming. Roll forming dies of each stand were designed according to the roll flower corresponding to each stand. FEM simulation and Taguchi method were adopted to optimize the designs of process and die considering the blank material, the gap of upper and lower rolls, the break down design, and the fin pass design. Three levels were adopted for each design parameter mentioned before. The goal of optimization is to minimize the variation of the welding line and the curvature of tube. The orthogonal array adopted is L9(34). The different weighting factors of the two quality indexes were studied. The simulation results had shown the break down design is the most significant design parameter. The material strength could strongly influence the dimension accuracy of tube. The stress distribution on the section area of tube dominated the variation of welding line. The optimum design could decrease the variation of welding up to 50%.
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Feng-ChienSu und 蘇峰堅. „Numerical Analysis of the Consititutive Model of Concrete-Filled Double Skin Tube“. Thesis, 2011. http://ndltd.ncl.edu.tw/handle/11200662558867934564.
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Shiu, Yu-Fen, und 徐育芬. „Double-O-Tube Shield Tunneling in Taipei Basin for Airport Access MRT“. Thesis, 2010. http://ndltd.ncl.edu.tw/handle/26268519666917104800.
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碩士國立交通大學
土木工程學系
98
Based on the construction of Taoyuan International Airport access MRT with the Double-O-Tube (DOT) shield tunneling method, this thesis studies the difficulties encountered during construction. Major difficulties discussed included: rolling of the shield machine, ground settlement due to tunneling, and speed and cost of DOT shield tunneling. Based on this study, the following conclusions are made. 1. Field data indicated that the maximum rolling angle was 0.38o, which was less than the limiting design rolling angle of 0.6o. The measures adopted by the contractor to correct the rolling angle included: reverse rotation of the cutter disc,grouting through holes on lining segments, and overcut of ground with the copy cutter. The reverse rotation of the cutter disc was use most often to correct the rolling angle. 2. The superposition method and the equal-area method were proposed to estimate the ground settlement due to DOT shield tunneling. It was found that the settlement troughs determined with the two methods were similar. The estimated settlement trough was in fairly good agreement with the measured settlement data. 3. The maximum ground settlements measured at six different sections varied from 12 to 34 mm. The ground loss due to DOT shield tunneling varied form 0.23 to 1.19%. The average ground loss was 0.76%. 4. In the departure section, the estimated speed of DOT excavation was 2.0 m/day.The measured speed of excavation was 2.5 m/day, which was 25% faster than the estimated speed. In the normal excavation section, the estimated speed of excavation was 4.3 m/day, and the measured speed was 3.9 m/day. 5. Based on the calculation of the Detail Design Consultant, the construction cost for the DOT tunnel is NTD 849,300 dollar/m. The construction cost for the traditional circular-section twin-tube shield tunnels is NTD 585,600 dollar/m. The DOT shield tunnel was more expensive to build mainly because the expensive DOT shield machine, and the complex DOT ring manufacture and assembly. 6. Although the total cost for the DOT shield tunnel was NTD 450,000,000 higher than that for the circular-section twin-tube shieldtunnels. However, with the DOT shield tunnel, the cost NTD 330,000,000 dollars to construct three cross-passages under the Danshuei River could be avoided. Consider the total cost of lot CA450A,the total cost with a DOT shield tunnel is NTD 1,960,000,000 dollars, and the total cost with traditional shield tunnels is NTD 1,910,000,000 dollars. With the two tunneling methods, the difference in total cost is only 2.5%.
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Kao, Chine-Yi, und 高慶懿. „An Experimental Study on a Double-tube Vertical Dynamic Hydrocyclone Oily Water Separator“. Thesis, 2006. http://ndltd.ncl.edu.tw/handle/75907912880484740276.
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碩士國立臺灣海洋大學
機械與機電工程學系
94
To prevent marine pollution by ships, the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78) regulated the oil concentration of oily water discharge. This study practically designed and constructed a double-tube vertical dynamic hydrocyclone oily water separator. Experiments are performed to study the effects of oil/water separation. The experimental results show that the separation effect depends on the oil content and concentration. Processing the oily water containing 3000ppm lubricant oil, the IMO discharge regulation is fulfilled under double-tube operation. Processing the bilge water from fishing boats, the IMO discharge regulation is fulfilled under single-tube operation. The separating efficiency for single-tube operation is around 83~93%. The single-tube separating efficiency reaches its maximum at a medium 2000 rpm speed, and at an overflow rate to underflow rate ratio of 5. The double-tube separating efficiency is much higher than the single-tube separating efficiency. The double-tube separating efficiency decreases with the increase of processing capacity, but maintaining a value above 88%. Keywords: bilge water, oily water, dynamic hydrocyclone, oily water separator, separation efficiency, overflow rate, underflow rate
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Yu-Hsiang und 林育詳. „Cyclic Response of Double-Skin Concrete Filled Steel Tube Column-to-Foundation Connections“. Thesis, 2001. http://ndltd.ncl.edu.tw/handle/94130075396094655463.
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碩士國立臺灣大學
土木工程學研究所
89
Hollow RC bridge piers have gained acceptance for the construction of tall bridge piers in Taiwan as a hollow section can effectively reduce the weight of the bridge pier while retain the flexural stiffness and strength to meet seismic resistant demands. Recent experimental research results have confirmed that properly proportioned double-skin concrete filled steel tube (DSCFT) members possess excellent axial and flexural resistance. It also appears that the use of DSCFT sections may be a promising alternative for tall bridge pier constructions. Therefore, a combined analytical and experimental research program has been conducted to investigate the practical details for connecting the DSCFT bridge column to foundation. In this study, a total of six specimens was fabricated, three employing single row of 12 bolts in one single ring of base plate (S-series) and three D-series specimens using two rows of 12 bolts in the two rings of base plate. All column specimens have the same cross section and base plate thickness. The primary test parameters include the connection types (S or D type) and the size of the connecting bolts. Test results confirmed that the both the S and D type connection details can develop the nominal flexural strength of the DSCFT section. In addition, tests of S type connection confirm that the ultimate connection strength and the failure modes can be satisfactorily predicted by incorporating a bilinear strain versus stress relationships (yield at 0.67Fu and fracture at Fu) for high strength anchor bolts and an ultimate strain of 0.005 for non-shrink grout underneath the base plate. The analytical moment versus curvature relationships were also constructed incorporating the mild steel tensile coupon strain versus stress relationships and a DSCFT confining pressure of 0.1fc’ into the Mander’s confined concrete model. It is illustrated that the experimental cyclic cantilever column load versus displacement response skeleton curves can be accurately predicted by employing the Moment-Area Method for all six DSCFT column specimens. Good agreements with test results are also observed for analytical cyclic responses simulated by using a three-parameter degrading beam-column element implemented in a general purpose analytical platform for inelastic structural analysis PISD2D.
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Choudary, Chaitanya P. „Experimental And Analytical Investigations Into Development Of Double-Tuned Expansion Chambers And Extended Concentric Tube Resonators“. Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/1270.
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The performance of an acoustic filter (or muffler) is measured in terms of one of the following parameters: Insertion Loss (IL), Level difference (LD) and Transmission loss (TL). All these three parameters may be evaluated in terms of the four-pole or transfer matrix parameters. Appropriate experimental setups have been designed and developed and practical considerations are described. Measured values of TL are compared with the analytically predicted values. It is shown that the Two-Source-Location method is relatively the best. To start with, the matrizant analysis of conical concentric tube resonators is validated experimentally. The effect of mean flow is investigated. The experimental setup is specially designed to measure the pressure transfer function across the test muffler. It is shown that there is reasonably good agreement between the predicted values of the transfer function and the measured ones for incompressible mean flow as well as stationary medium.
To measure insertion loss of muffler, one needs to calculate the source impedance. The internal impedance of a sound source can be measured using direct or indirect methods. The four-load SPL measurement method is one such indirect method wherein there are three nonlinear equations in terms of two unknowns which makes one of the equations redundant. This leads to erroneous results. To overcome this inherent weakness, two alternatives multi-load methods have been offered in the literature; namely, the least squares and the direct least squares method, to analyze the measured data used for four (or more) different loads. These two methods produce better results than the four-load SPL measurement method used earlier. These measurement methods have been tested on a loudspeaker to measure its source impedance and the results are validated with a known additional acoustic load.
Simple expansion chambers, the simplest of the muffler configurations, have very limited practical application due to the presence of periodic troughs in the transmission loss (TL) spectrum which drastically lower the overall TL of the muffler. Many of the present days automobile exhaust systems make use of the extended tube mufflers, often with perforated ducts because of their low back pressure and good acoustic performance. Tuned extended inlet and outlet can be designed to nullify three-fourths of these troughs, making use of the plane wave theory. However, these cancellations would not occur unless one altered the geometric lengths for the extended tube and perforated tube resonators in order to incorporate the effect of the evanescent higher-order modes (multidimensional effect) through end corrections or lumped inertance approximation at the area discontinuities or junctions. This is investigated here experimentally as well as numerically (through use of 3-D FEM software) for a moving medium as well as stationary medium. The effect of temperature on the end corrections is also investigated.
These tuned extended-tube chambers, however, suffer from the disadvantages of high back pressure and aerodynamic noise generation at the area discontinuities. These two disadvantages can be overcome by means of a perforated bridge between the extended inlet and the extended outlet. One dimensional control volume approach is used to analyze this muffler configuration. It is validated experimentally making use of the two source-location method, which is proven to be the best method available to us. It is thus shown that the inertance of holes plays a role similar to the lumped inertance generated by evanescent 3-D modes at the terminations of the quarter wave resonators in the case of the double-tuned extended tube chambers. The effect of mean flow is also investigated. The resultant transfer matrix is then used to carry out a systematic parametric study in order to arrive at empirical expressions for the differential lengths as well as the end corrections. Thus, an extended concentric tube resonator can be tuned such that the first three troughs that characterize the corresponding simple chamber transmission loss (TL) curve may be eliminated making use of the proposed procedure. In fact, the entire TL curve at low and medium frequencies may be substantially lifted, making the tuned extended concentric tube resonator a viable design option.
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Wei, Hsi-Hsien, und 魏希賢. „Cyclic Responses of Embedded Double-Skin Concrete Filled Steel Tube Column-to-Foundation Connections“. Thesis, 2002. http://ndltd.ncl.edu.tw/handle/09971438939635015306.
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碩士國立臺灣大學
土木工程學研究所
90
Hollow RC bridge piers have gained acceptance for the construction of tall bridge piers in Taiwan as a hollow section can effectively reduce the weight of the bridge pier while retain the flexural stiffness and strength to meet seismic resistant demands. Recent experimental research results have confirmed that properly proportioned double-skin concrete fill steel tube (DSCFT) members possess excellent axial and flexural resistance. It also appears that the use of DSCFT sections may be a promising alternative for tall bridge pier constructions. Therefore, a combined analytical and experimental research program has been conducted to investigate the practical details for embedded DSCFT column to foundation connections. In this study, a total of six specimens was fabricated, three employing stiffeners above the base plate (TS-series) and three BS-series specimens using stiffeners below the base plate. The column embedment height variations denote 1H, 2H and 3H,in each three TS or BS series specimens include 0.3D, 0.6D and 0.8D (D is external diameter of the DSCFT column), respectively. All column specimens have the same cross section and base plate thickness. The primary test parameters include the stiffener types (TS or BS type), the embedment length and the size of the anchor bolts. Test results confirmed that the anchoring strengths of the embedded column include: 1) the flexural strength due to the lateral bearing strength of the DSCFT wall to adjacent concrete foundation, Mberaing, 2) the flexural strength due to the vertical bearing resistance of the concrete against the cantilever base plate Moverhang, and 3) the tie down flexural strength of the base plate considering the anchor bolt strength, Mbolt. Both the TS and BS type connection details can develop the nominal flexural strength of the DSCFT section if the embedments (0.6D and 0.8D) are adequate. Tests confirm that the ultimate connection strength and the failure modes can be satisfactorily predicted by incorporating proper models for concrete and anchor bolts. The analytical moment versus curvature relationships were also constructed incorporating the mild steel tensile coupon strain versus stress relationships and a DSCFT confining pressure of 0.01fc’ into the Mander’s confined concrete model. It is illustrated that the experimental cyclic cantilever column load versus displacement response skeleton curves can be accurately predicted by employing the moment curvature area method for all six DSCFT column specimens. Good agreements with test results are also observed for analytical cyclic responses simulated by using a three-parameter degrading beam-column elements and joint element implemented in a general purpose analytical platform for inelastic structural analysis PISA2D.
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Yi-ChengHung und 洪禕辰. „Finite Element Analysis of Concrete-Filled Double Skin Tube Connection for Offshore Wind Turbine“. Thesis, 2015. http://ndltd.ncl.edu.tw/handle/3ma99g.
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碩士國立成功大學
土木工程學系
103
Finite element analysis of Concrete-filled double skin Connecting tube for offshore wind turbine Yi-Cheng Hung Hsuan-Teh Hu Department of Civil Engineering National Cheng Kung University SUMMARY Transition piece (Grouted connection) is widely used in offshore engineering, e.g., wind power, oil and gas, and act as an important part to transit the loading from superstructure to foundation. In this thesis, I use the finite element analysis software, ABAQUS, to simulate the behavior of grouted connections when subjected loading. The thesis try to show the slightly rise and fall on the surface of steel tube due to produce, which cause the member to gain the loading capacity. For simulate the condition of slightly rise and fall on the surface of steel tube, we arrange some assistant points on the surface of steel tube. The value of assistant points were picked from reasonable range, and picked by normal distribution method or choose only one value as representation. Finally verify the feasibility of this simulation by compare the result with the conclusion of experiment, and to propose a representative value to exhibit the roughness of the surface of steel tube. At the end of this thesis, further studying the effect on the difference of the length of transition piece. Key words : Transition piece, Grouted connection, ABAQUS Introduction The energy resources in Taiwan is mainly depend on nuclear power and thermal power. Now, Taiwan is going to expand green power, and wind power is one of the green powers be emphasized, it’s expect to reach 12,502MW of total capacity in 2030, including 5MW offshore wind turbines 600 sets and 2.5MW onshore wind turbines 450 sets, and the offshore wind farm is located at Chang-Hua, Yun-Lin and Peng-Hu. Materials and methods The type of foundations of offshore wind turbine is depend on the condition of the sea which wind farm locate, even though the depth in the Taiwan strait is between 15m ~ 20m, it is well suited to mono-pile foundation, but after consider the weak seabed of Taiwan strait, and offshore construction ability, finally select the Jacket foundation (Group piles) as design. This thesis use finite element software, ABAQUS, to simulate the loading behavior of transition piece, we set up the model refer to the scale of reality experiment, and compare the result of simulation with the data of experiment. Results and discussion The simulation show that if the assistant points distributed to a specific span, and the magnitude of rise and fall is setting in a specific value, then the result of simulation approach the experiment that is done by Peter Schaumann (2010). This thesis keep on studying the effect on the difference of the scale of transition piece, and the effect on the difference of the strength of materials. We discuss four different values of length of transition piece (L_G), and four different values of thickness of transition piece (t_G). The result show that the loading capacity of transition piece is direct proportion with the length of transition piece, but the effect of the thickness of transition piece is not that simple, with increased the thickness of transition piece, the loading capacity will raise up first, and fall down after reach a peak value. Conclusion After testing, we found that if the model set up without assistant points, the transition piece may punching directly when loading comes up, it is almost no loading capacity. We think the roughness of the surface of steel tube is the key point to lead to friction, in order to show the behavior of roughness, not only the friction coefficient of material should be set, but also the rise and fall of the surface of steel tube should be simulated. After our simulation and compare the result with experiment, the model can approach experiment when the ratio of number of assistant points (N) and length of transition piece (L_G) equal to 0.5, and the rise and fall of the surface of steel tube set to 0.0266 mm.
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Chin-LiShen und 沈晉立. „Growth and Physical Properties of Higher Manganese Silicide Nanowire Arrays with Double Tube CVD“. Thesis, 2015. http://ndltd.ncl.edu.tw/handle/yk936u.
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碩士國立成功大學
材料科學及工程學系
103
In order to study nanoscale manganese silicide materials in physical properties and potential application, synthesis techniques of nanostructure must be developed. In this work, we report a chemical reaction method to synthesize higher manganese silicide nanowires. Dense silicon nanowire arrays fabricated by chemical etching reacted with MnCl2 precursor by novel double tube method. In double tube system, if we carefully controlled argon flow rate and ambient pressure, it will be able to efficiently increase vapor pressure of source and stable source vapor provided. It is crucial that high quality higher manganese silicide nanowire were obtained with original nanostructures preserved by using double tube method. Characterization of nanowires were investigated by XRD, SEM, TEM and phase identification were performed by HRTEM, FFTs, SAED achieved single crystalline nanowire of actual HMS phase Mn27Si47 with tetragonal structure. Magnetic properties measurement show that Mn27Si47 nanowire exhibited ferromagnetic with enhanced Curie temperature compared with bulk HMS phase, and field emission measurement show excellent field enhancement factor 3307 with nanowires 20 μm long.
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Lee, Shen-Chung, und 李勝宗. „Three-Dimensional Analyses of Deformations in Mountain Tunnels and Double-O-Tube Shield Tunnel“. Thesis, 2016. http://ndltd.ncl.edu.tw/handle/725t22.
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博士國立臺北科技大學
工程學院工程科技博士班
104
The magnitude and distribution of tunnel deformation are widely discussed topics in tunnel engineering. In this thesis, a three-dimensional finite element program was used for the analysis of tunnel deformation behavior under different geological conditions. In the process of the analysis, the tunnel cross-section sizes, the round excavation lengths, and the primary supports are simulated as close to the practical tunneling works as possible. The constitutive models for the medium surrounding the tunnel are different, just depending on the medium is rock or soil. According to the analytical results, geological conditions play a significant role in the deformation behavior. In general, large tunnel openings situated in poor quality rock mass have a larger deformation. If the time-dependent weakening of the rock mass is not considered, the tunnel deformation reaches its maximum value at a distance of two to three diamerers behind the excavation face. At the excavation face, the ratios of vertical displacement to the maximum vertical displacement are approximately 1/3 to 1/2, the weaker geological conditions result in greater ratio value. The pre-deformations ahead of the excavation face are gradually reduced with increasing distance from the face. At a distance of one diameter ahead of the face, the pre-deformation values are reduced to 10% of the maximum displacement. In respect to the constitutive law of rock mass, the displacements analyzed by the Hoek-Brown and Mohr-Coulomb models are almost identical; in other words, both models are suitable for the numerical analyses of mountain tunnels. In the numerical analysis of shield tunneling, except the consideration of contraction parameter, the use of soil model should consider the non-linear dependency on soil stiffness and strain amplitude. In this study, the Harding Soil model with small-strain stiffness (HS-small) allows for even more realistic modelling compared with the other models. When executing the numerical analysis for shield tunneling, except the general used Mohr-Coulomb model, it is recommended to check the tunnel deformation behavior with the advanced HS-small model.
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黃建隆. „Simulation Analysis of Optimal Thermal Efficiency of R134A Refrigerant for Double Tube Heat Exchanger“. Thesis, 2019. http://ndltd.ncl.edu.tw/handle/buage4.
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博士國立高雄科技大學
機械工程系
107
Heat exchangers have always been important devices for advancements and developments in industrial and commercial activities. In industrial production, heat exchangers have a wide scope of applications and are a type of universal technological equipment designed to achieve heat transfer between materials. In this study, COMSOL simulation software was employed and continuity equations, momentum equations, kinetic equations, turbulent models, and appropriate boundary conditions were adopted to investigate the heat transfer characteristics of fluids in helical-coil and U-shaped double tube heat exchangers. In the T7 helical-coil double tube heat exchanger with R134A refrigerant at the tube end, convergence was not attained as the change in thermal efficiency was 0.002; however, in the T7 helical-coil double tube heat exchanger with R134A refrigerant at the shell end, convergence was attained as the change in thermal efficiency was 0.001. This configuration had the best heat transfer efficiency for helical-coil double tube heat exchangers. When the T1 to T8 helical-coil double tube heat exchangers had an equal number of turns, the working fluid R134A had a higher heat transfer efficiency when it was placed at the shell end than when it was placed at the tube end. Therefore, it is suitable for high-temperature R134A refrigerant to flow through the exterior (shell-side) which covers the cooling fluid flowing through the interior (tube-side), so as to achieve a higher heat transfer efficiency. In the S7 U-shaped double tube heat exchanger with R134A refrigerant at the shell end, convergence was attained as the change in thermal efficiency was 0.0011. This configuration had the best heat transfer efficiency for U-shaped double tube heat exchangers. For an equal number of segments in the S1 to S8 U-shaped double tube heat exchangers, the working fluid R134A had a higher heat transfer efficiency when it was placed at the shell end than when it was placed at the tube end. Therefore, it is suitable for high-temperature R134A refrigerant to be flowed through the exterior (shell-side) which covers the cooling fluid flowing through the interior (tube-side), so as to achieve a higher heat transfer efficiency. The U-shaped double tube heat exchangers had better heat transfer efficiencies. At equal heat transfer areas of 823.74 cm2 and at equal numbers of turns/segments (six), the S6 U-shaped double tube heat exchanger enhanced its heat transfer efficiency by 0.002. In other words, it achieved a heat transfer efficiency of 0.9927, which was slightly greater (by 0.0007) than the T7 helical-coil double tube exchanger’s heat transfer efficiency, which was 0.9920. However, the S6 exchanger’s total heat-transfer area was 137.29 cm2 less and the material cost was comparably lower; hence, the S6 U-shaped double tube heat exchanger was the optimal type of heat exchanger in this study.
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Santos, Francisco Martim Pereira. „Modelação Numérica do Comportamento ao Fogo de Colunas Mistas de Secção Circular de Dupla-Pele e Duplo-Tubo“. Master's thesis, 2021. http://hdl.handle.net/10316/98118.
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Dissertação de Mestrado Integrado em Engenharia Civil apresentada à Faculdade de Ciências e TecnologiaNos últimos anos, a utilização de elementos mistos de aço e betão tornou-se cada vez mais popular, em particular as colunas mistas de perfil tubular de aço preenchidas com betão. A dispensa de cofragens, maior capacidade resistente axial e as reduzidas dimensões da secção transversal são algumas das razões para o sucesso deste tipo de coluna. Porém, num mercado onde se constrói edifícios cada vez mais altos, a utilização de elementos esbeltos implica a existência de soluções que assegurem sua capacidade resistente não só em temperatura ambiente como também em situação de incêndio. Na busca deste tipo de soluções, surgiram estudos experimentais e numéricos em colunas mistas de duplo-tubo, uma variação das colunas mistas de dupla-pele já utilizados em situação de sismo. As colunas de dupla-pele são compostas por dois tubos de aço, um externo e outro interno, com o anel entre eles preenchido por betão, enquanto nas colunas de duplo-tubo a seção é completamente preenchida por betão. Desta forma, nas colunas de duplo-tubo, o núcleo de betão e o tubo interno podem proporcionar uma maior capacidade resistente em situação de incêndio, visto que se encontram submetidos a temperaturas relativamente mais baixas que o tubo externo e o anel de betão. O trabalho consiste numa análise numérica, pelo Método de Elementos Finitos, de colunas de dupla-pele e duplo-tubo em situação de incêndio e que tinham sido ensaiados anteriormente na Universidade de Coimbra. Os estudos experimentais e numéricos tiveram como objetivo analisar o nível de carregamento e a rigidez axial e rotacional em situação de incêndio. Os resultados numéricos são então comparados com os resultados experimentais para se validar o modelo, analisando os deslocamentos axiais e as forças de restrição, e a influência de diversos parâmetros na capacidade de resposta do modelo.
In recent years, the use of composite elements of steel and concrete has become increasingly popular, in particular concrete filled steel tubular composite columns. Dispensing with formwork, greater axial strength and reduced cross-sectional dimensions are some of the reasons for the choice of this type of columns. However, in a market where increasingly taller buildings are built, the use of slender elements implies the existence of solutions that ensure their loadbearing capacity not only at ambient temperature but also in a fire situation. In the search for this type of solutions, experimental and numerical studies on double-tube composite columns emerged, a variation of the double-skin composite columns already used for earthquake situation. The double-skin columns are composed of two steel tubes, one external and the other internal, with the ring between them filled with concrete, while in the double-tube columns the section is completely filled with concrete. Thus, in double-tube columns, the concrete core and the inner tube can provide a greater loadbearing capacity in a fire situation, as they are subjected to relatively lower temperatures than the outer tube and the concrete ring. The work consists in a numerical analysis, using the Finite Element Method, of double-skin and double-tube columns fire tested some years ago at the University of Coimbra. The experimental and numerical studies aimed to analyze the influence of the loading level and axial and rotational stiffness in fire situation. The numerical results are then compared with the experimental results to validate the model, the axial displacements and restraint forces, and the influence of several parameters on the responsiveness of the model are analyzed.
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Wu, Chao-Yu, und 吳釗宇. „Gas sensing properties of ZnO nanowires growned by a double-tube vapor-liquid-solid process“. Thesis, 2009. http://ndltd.ncl.edu.tw/handle/47977946448606384227.
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碩士國立臺灣師範大學
工業教育學系
98
This study is aiming on demonstrating Zinc Oxide (ZnO) nanostructures were successfully grown on Al/glass substrates by using a double-tube vapor-liquid-solid (VLS) technique without any gold (Au) metal catalyst or template. When the temperature was set at 900◦C, ZnO nanostructures were grown successfully under controlled. With the XRD analysis, ZnO nanowires were preferably grown in (002) direction and were in direct ration to the oxygen level. Also, the result of this study showed that the ratio of oxygen gas flow has the impact of the length and density of ZnO nanowires. ZnO nanowires were grown on Al/glass substrates in high density with 8 sccm oxygen gas flow under observing by Scanning Electron Microscope (SEM). It is also found that the ZnO nanowire 8 sccm sample has an outstanding electrical conduction property to measure the I-V characteristics. Moreover, ZnO nanowire has a better sensitivity to NO2 in compare of CO. Its response and recovery time are shorter with an excellent long-term reproducibility and stability. The sensitivities are 23、33、41 when it is to detect NO2 at 20 ppm, 60 ppm, 100 ppm, respectively, at 175◦C.
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Chen, Tuo-Jung, und 陳拓融. „Three-Dimensional Numerical Analysis of Double-O-Tube(DOT) Shield Tunneling Under Different Drainage Conditions“. Thesis, 2018. http://ndltd.ncl.edu.tw/handle/apws5t.
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碩士國立臺北科技大學
土木工程系土木與防災碩士班
106
The Double-O-Tube shield tunnel (DOT) is widely developed in Japan, China and other regions. The case of this study, "Taoyuan Airport Taipei Triple Section CA450A" project is the first double-circle shield tunnel in Taiwan, with its special research value. This case is not easy to use as a communication channel between tunnels because of its river bed. It introduces a special section of double-circle shield tunnel under comprehensive consideration. In this study, the PLAXIS 3D 2017 finite element analysis software was used to simplify and analyze the three-dimensional excavation model for the double-circle shield model. This paper uses three monitoring sections to model and uses Mohr-Coulomb, hardened soil and hardening. Three soil combination rates, such as soil small strain, are combined with drainage, undrained A, undrained B, and undrained C. The purpose of the study is to find out the differences and similarities in various modes, and compare the models. The mode is closer to the monitoring data. The results indicate that similar subsidence results can be obtained regardless of the drainage mode when other strength parameters are unchanged; in all modes, the amount of subsidence obtained by different drainage behaviors has a regularity; The results of the closest field monitoring can be obtained after analysis of the hardened soil pattern in the three sections.
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Wang, Yi-Ting, und 王怡婷. „Optimal Design and Manufacture of Double Flat-Panel Speakers Stiffened by Nano-Carbon Tube Composites“. Thesis, 2010. http://ndltd.ncl.edu.tw/handle/38771876706349448432.
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碩士大葉大學
工業工程與科技管理學系
98
The main object of this paper is designed and developed a double flat-panel speaker stiffened by nano-carbon tube composites which it had thin thicknesses, broad frequency and acoustic fidelity vigorous not distorted it. Two types of vibrating plate, namely, a high audio speaker and medium-low audio speaker constructed on the basis of the manufacture technique and sound pressure theory are developed for the design and analysis of double flat-panels. The study is analyzed the frequency and sound pressure value of double flat-panel speakers with different design parameters such as stiffness and weight of composite panels, boundary condition and spring constant of suspension system and vibration area which are constructed using a finite element constructed on the basis of the software ANSYS. The double flat-panel speakers can be applied to the general plane video and music electronic products loudspeaker system, achieves nowadays pursues the monitor more and more thin tendency. The double rectangular flat-panel speaker can be used in dual-channel flat-panel speakers for portable DVD players and notebook computers ... and other products. According to developed the analytical method of a set of simulation and optimal design is proceed to optimal design of multiple objective function for stiffened composite double flat-panels in 100Hz~20KHz frequency zones. The 100Hz~20KHz frequency zones had divide into 4 zones, every zones variable values multiply by weight was the sum that was the objective function of multiple optimal design. In the limit small thrust of low power, is used the optimal method to find the best manufacturing parameters (includes the lengths of flat-panel speaker, spring constant of suspension system, stiffened types and vibration lengths) made the sound pressure value curve had smooth and get the best sound pressure value. Therefore, the optimal manufacturing parameters would manufacture double flat-panels to measured sound pressure curve that compared experimental values and theory values.
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Tsai, Shih-Heng, und 蔡世桓. „Nonlinear Analysis of Double-Skin Concrete Filled Tube Subject to Axial Compression and Bending Moment“. Thesis, 2006. http://ndltd.ncl.edu.tw/handle/86723765577269248263.
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碩士國立成功大學
土木工程學系碩博士班
94
This paper use ABAQUS software to analyse the Double-Skin Concrete Filled Tubes (DS-CFT) that subject to axial compression and bending moment, then compare the analysis results with experimental data of national earthquake center. By the way, we can find the Fl, K3, and K4 of a DS-DFT subject to such loads, understand the benefit that concrete can produce in DS-CFT so, and calculate the experience formulas used for material parameters. By the result analysing, we can find that the specimen under pure bending can’t let the concrete keep its compressive resistibility because of lacking the axial compression, therefore the strength of such specimen is less than others, but DS-CFT can still offer a certain Fl that is much stronger than CFT. Besides, we find the experience formula and K2 of CFT are not suitable for DS-CFT specimens, K2 value of CFT will lead to a strain that is too large. so this paper repeated trying for many times, induct new values of K2, and find out the suitable material parameters and experience formulas again.
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Ren, Q.-X., C. Hou, Dennis Lam und L.-H. Han. „Experiments on the bearing capacity of tapered concrete filled double skin steel tubular (CFDST) stub columns“. 2014. http://hdl.handle.net/10454/10283.
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noTapered concrete filled double skin steel tubular (CFDST) columns have been used in China for structures such as electricity transmission towers. In practice, the bearing capacity related to the connection details on the top of the column is not fully understood. In this paper, the experimental behaviour of tapered CFDST stub columns subjected to axial partial compression is reported, sixteen specimens with top endplate and ten specimens without top endplate were tested. The test parameters included: (1) tapered angle, (2) top endplate thickness, and (3) partial compression area ratio. Test results show that the tapered CFDST stub columns under axial partial compression behaved in a ductile manner. The axial partial compressive behaviour and the failure modes of the tapered CFDST stub columns were significantly influenced by the parameters investigated. Finally, a simple formula for predicting the cross-sectional capacity of the tapered CFDST sections under axial partial compression is proposed.
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Ka, Wan-yi, und 柯婉伊. „Ground surface settlement of Double-O-tube shield tunnel for Airport Access MRT in Taipei Basin“. Thesis, 2011. http://ndltd.ncl.edu.tw/handle/3jxzaa.
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碩士國立臺北科技大學
土木與防災研究所
99
This study evaluated the ground surface settlement caused by double-o-tube shield tunnel construction, using Taoyuan International Airport MRT Line Taipei-Sanchung Section CA450A as an example. PLAXIS 2D software of the infinite element method was used to conduct numerical analysis on the single bore tunnels at various depths of earth covering according to the geologic conditions of the sections in actual cases, in order to compare the parameter relationship between the two numerical analysis methods of percentage of area reduction of the tunnel and soil released stress based on the same maximum ground surface settlement. In the case of DOT shield tunnel, PLAXIS numerical analysis was carried out on the ground surface settlement of 7 monitored sections. Through intercomparison among the ground surface curve by the numerical analysis, settlement observation data by in-situ monitoring and empirical formula calculation in terms of the ground surface settlement trough, the applicability of PLAXIS on analyzing the Double-o-tube shield tunnel has been verified, which could help to understand possible influences in the process of Double-o-tube shield tunnel excavation and influence range to adjacent structures, and provide reference for future Double-o-tube shield tunnel project application. The maximum ground surface settlement relationship of the percentage of area reduction of the tunnel and soil released stress by the numerical analysis of the parallel-tube shield tunnel presented a non-linear relationship at 20m of the central depth of the tunnel, and presented a linear relationship when it reached 24m and 27m of the central depth of the tunnel. In the case of Double-o-tube shield tunnel of Taipei-Sanchung Section, the ground surface settlement troughs of the Double-o-tube shield tunnel calculated by way of empirical formula superposition method and the equal-area method were similar according to the comparison of results by the three methods of numerical analysis, empirical formula and in-situ monitoring. However, in the comparison of results of empirical formula calculation and in-situ monitoring, the settlement troughs were identical in shape and trending but the maximum ground surface settlement values at the tunnel center presented certain difference. In the comparison of the results of numerical analysis simulation and in-situ monitoring, the maximum ground surface settlement values at the tunnel center and the shape and trending of ground surface settlement troughs were identical. The soil released stress value obtained by the numerical analysis presented a direct proportional linear relationship with the maximum ground surface settlement and the in-situ loss rate, which can be used in numerical analysis of the soil released stress of Double-o-tube shield tunnel in the future so as to predict the upper and lower limits of possible ground surface settlement.
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Kuan-ChinWang und 王冠欽. „Thermal efficiency analysis of double pipe heat exchanger with elliptical tube using 3D Lattice Boltzmann method“. Thesis, 2018. http://ndltd.ncl.edu.tw/handle/582842.
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42
Dong, Yu-Wei, und 董育維. „Direct growth of Ni particle on Li-Al layered double hydroxide as catalyst tube and application“. Thesis, 2018. http://ndltd.ncl.edu.tw/handle/mja9hn.
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碩士國立中興大學
材料科學與工程學系所
106
Steam reforming is a large-scale hydrogen production method commonly used in the industry, and its efficiency is affected by the catalyst and the catalytic converters . In this study , Growing of high surface area catalyst on stainless steel tube as an ethanol steam reforming reactor . Frist, Li-Al-CO3 Layered Double Hydroxide (LDH) support is deposited on 304 stainless steel tube using electrodeposition method and nickel precursor is grown homogeneously over LiAl LDH surface by immersed and stirred in a nickel carbonate aqueous solution. After reduction, metal Ni and NiO nanoparticle layers is developed on LDH sheet surface, and the thickness and the nickel loading increases when stirring for longer . The process does not need to be repeat calcined, and avoids the use of nickel nitrate solution . The hydrogen selectivity can reach more than 84% at 500 °C. When the thickness of the nickel catalyst layer and the reaction area increase, the hydrogen conversion and lifetime increase. The hydrogen conversion of the catalyst tubes with different stirring times is 180_min R (11 %) > 30 _min R (7.5 %) > LiAl LDH (6.5 %). 180_min R has the longest catalytic lifetime, and its hydrogen conversion gradually decreases after 2.5 hours .
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LEE, PAI-CHIN, und 李百欽. „Study on Heat Transfer of R134a Refrigerant in Double Tube Heat Exchanger by Heat Radiation Effect“. Thesis, 2019. http://ndltd.ncl.edu.tw/handle/f4mk53.
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碩士和春技術學院
電機工程研究所
107
This paper mainly establishes the dropout mode of the three-dimensional turbulent flow field of the double-casing heat exchanger, discusses the heat transfer efficiency of the R134a refrigerant in the heat exchanger, and analyzes whether the heat exchanger has natural convection with or without air radiation. Calculate the temperature change at the outlet side of the refrigerant. The results show that when there is air convection without considering heat radiation, the R134a refrigerant in the front, middle and back sections has a larger temperature drop than the airless convection, and the closer to the outer casing side, the larger the cooling rate is, the biggest difference It is located at the inner wall of the outer tube of the rear section, with a temperature difference of 2.30K. In addition, there is no air convection. When comparing only the heat radiation state, the R134a refrigerant in the front, middle and rear sections will have a large temperature drop when considering the heat radiation, and the closer to the outer casing side The larger the temperature difference, the biggest difference is in the inner wall of the inner tube of the rear section, and the temperature difference is 5.05K. Therefore, it can be determined that the heat radiation still has an influence on the change of the temperature value of the heat exchanger outlet. Keywords：R134a refrigerant, heat radiation effect, heat transfer efficiency, double tube heat exchanger.
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Yu-ChaoChu und 儲于超. „Forced convection heat transfer characteristics by controlling concurrent flow rates of a NanoPCM emulsion/water through outer annulus/inner tube of a concentric double-tube duct“. Thesis, 2019. http://ndltd.ncl.edu.tw/handle/aw9ky2.
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碩士國立成功大學
機械工程學系
107
In present study demonstrates, via heat transfer experiments complementary with numerical simulations, the feasibility of achieving enhanced forced convection heat transfer of laminar water flow in an isoflux heated circular tube by inserting a concentric circular tube and controlling the concurrent flow distribution through the resulting concentric double-tube duct. In the experiment, copper was used as the material of the round tube, and the outer tube size was: length 1250 mm, outer diameter 10 mm, inner diameter 9.1 mm. The inner tube has a length of 2060 mm, an outer diameter of 8 mm, and an inner diameter of 7.4 mm. The inner and outer tube gap is 1.1mm. A tightly wound nickel-chromium resistance coil is provided in the heating section of the copper tube to provide iso-flux heating conditions. In the experimental conditions of fixed total flow and heating power, the heat transfer gain is proportional to the flow ratio. If the working fluid is a nanoemulsion, the higher the heat transfer effect will be higher than the pure water. . In the fixed total flow rate, the nanoemulsions with concentration of 2% and 5% are respectively in the heating power 110W flow ratio 0.7 and the heating power 110W flow ratio 0.27, and the convection has the best gain of 1.32 times and 1.88 times. Key words: Concentric double tube, Nano-PCM emulsion, Phase change material, Laminar forced convection.
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Cutler, Geoffrey Lloyd. „CHARACTERIZING VALPROIC ACID-INDUCED DNA DOUBLE STRAND BREAK REPAIR“. Thesis, 2012. http://hdl.handle.net/1974/7597.
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The teratogenic effects of valproic acid (VPA) are well known, though its teratogenic mechanism remains unknown. VPA induces oxidative stress, which may lead to double strand breaks (DSBs) in DNA. Though the cell may repair this damage via homologous recombination (HR) and non-homologous end joining (NHEJ), repair is not always error-free; genomic instability may arise from gene deletions, amplifications, rearrangements, and loss of heterozygosity. Such alterations may underpin VPAʼs teratogenicity. The present study evaluated VPAʼs ability to induce NHEJ and HR and characterized the changes in expression of two proteins key to HR (RAD51) and NHEJ (XRCC4).
Using pKZ1 transgenic mice (C57BL/6 genetic background), we sought to measure NHEJ events via X-gal staining. Although consistent staining was observed in adult male brain (positive control), no staining was observed in embryos 12 or 24 hours after in utero exposure to a teratogenic dose of VPA (500 mg/kg, maternal subcutaneous dose) on gestational day 9 (GD9).
To determine whether the lack of staining observed in embryos was due to low/absent expression of key DSB-repair proteins, we measured mRNA/protein expression of RAD51 and XRCC4 in C57BL/6, GD9-exposed embryos and maternal brain. One hour after treatment, XRCC4 was increased at the protein level in brain and embryo. RAD51 was not increased in embryos and not detected in adult brain. These data suggest that embryos do possess the protein mediators of NHEJ and HR and that VPA-induced changes in expression of XRCC4 may influence the type of repair pursued, potentially affecting DSB repair fidelity (accuracy).
Determination of fidelity of VPA-induced HR was attempted with the Chinese hamster ovary cell line (CHO33) using DNA sequencing; low template concentration and purity precluded successful sequencing of DNA from recombinant colonies and the assessment of fidelity.
Overall, these data demonstrate that the lack of X-gal staining observed in pKZ1 embryos is not due to an underexpression of at least one key protein in the NHEJ pathway. Furthermore, a VPA-induced change in the the type of repair pathway pursued by the embryo may have teratological implications.Thesis (Master, Pharmacology & Toxicology) -- Queen's University, 2012-10-15 11:06:30.613
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Lin, Chia-Ming, und 林家明. „Development and Performance Analysis of Heat Pump System with Air Source-Water Source Double-Effect Finned Tube Heat Exchanger“. Thesis, 2017. http://ndltd.ncl.edu.tw/handle/9xfdgc.
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碩士國立勤益科技大學
冷凍空調系
105
This paper adopts prospective design, a novel product concept is proposed in the concept of water source heat pump based on the air source heat pump, integrated with the advantages of air source and water source heat pump systems to create the advantage of double-effect heat pump. Aims at innovative design of evaporator. The new system uses the design of novel finned-tube evaporator. The evaporator extracts heat from air source and water source simultaneously, known as air-water double-effect finned-tube evaporator. The system can switch the mode to air source or water source heat pump mode according to the user requirement, which is to say, it can make hot water only, and can make hot water and chilled water at the same time, enhancing the double-effect heat pump performance. The business package FLUENT of Computational Fluid Dynamics (CFD) is used for analysis, the simulation software validates the feasibility of the new system design. According to the simulation analysis results, the air-water double-effect finned-tube evaporator in this new system can implement effective heat exchange between the refrigerant side and chilled water side, implementing steady running and the originally designed performance and capacity. The performance of the prototype developed in this study is tested at the enthalpy difference laboratory, and the heating capacity and refrigeration capacity are tested under different environmental conditions. The experiment validates the reliability of the new system in the air source and water source operation modes. According to the experimental analysis results, when the air source heat pump is used, the heating capacity is higher than the design requirement 7.5kW . When the water source heat pump is used, the heating capacity meets the design requirement 7.5kW. The refrigeration capacity is affected by environmental factors, so it fails to meet the design requirement 5.5kW , but the overall performance is not affected. It is proved this system can run under various environmental heating conditions in air source and water source modes effectively, and can run stably to provide system heating and refrigeration capacities. According to the comparison between simulation and experimental data of operation in water source mode under different environmental conditions, the error rate of refrigeration capacity of this system is 4~13%.
47
Liu, Li-Chien, und 劉立謙. „Improvement in performance of double-pass laminar counterflow concentric-tube mass exchangers under sinusoidal wall fluxes and external recycle“. Thesis, 2004. http://ndltd.ncl.edu.tw/handle/44499155036947552544.
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碩士淡江大學
化學工程與材料工程學系碩士班
94
A new double-pass mass exchanger with sinusoidal wall fluxes is obtained by inserting a permeable membrane into a circular tube. There are ten recycle types developed in this study to improve the device performance. The resultant mathematical formulation of such double-pass devices was derived theoretically and the approximation solution was obtained by using the orthogonality principle and forbenius method. The concentration distribution and mass transfer efficiency were represented graphically, and compared with those in single-pass devices of the same working dimensions. Considerable improvement of the device performance is obtainable by introducing recycle-effect concept for conducting double-pass operations. The effects of permeable-barrier position and recycle ratio on the mass transfer efficiency as well as on the of power consumption increment have also been discussed.
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Lee, Kun-Chung, und 李坤忠. „Crystal Morphology and Growth Kinetics of Calcium Carbonate in A Semi-batch Reactor with Double-tube Gas Injection Nozzle“. Thesis, 1993. http://ndltd.ncl.edu.tw/handle/42013607132017778138.
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碩士國立臺灣大學
化學工程研究所
81
For sparingly solube crystals the solution method was usually employed to study the kinetics of primary nucleation and crystal growth. However, the gas bubbling method was mainly used in the industrial production of Calcium Carbonate and in the treatment of softening water. Few reports have been found in the literature to study the kinetics of primary nucleation and growth by the gas-injection method. Control of crystal morphology was investigated in this study. It is found that the pH value and the initial Calciumion concentr -ation,but not the supersaturation, are the factors which dete -rmine whether calcite, aragonite, or vaterite would be nucleated from a supersatration Calcium Carbonate solution. The Calcium ion concentration for themaximum yield of calcite is found to be 0.015 M. Aragonite isonly found when the pH value is less than 8.0. Low yield ofcalcite of can be obtained by the gas- injection method. Additionally, the growth of small calcite (20－163 micro meter) and large calcite crystal (163－327.5 micro meter) were conducted in the supersaturation range of 0.1－1.49 nad 0.51－ 2.03, respectively. The results show that surface integration was the rate- determining step for the growth of small and large calcite crystals. The growth rate of large calcite crystal was size independent, but that of small calcite was size dependent.
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Chen, Tsung-Ching, und 陳宗慶. „The recycle effect on the collector efficiency improvement of double-pass sheet-and-tube solar water heaters with external recycle“. Thesis, 2005. http://ndltd.ncl.edu.tw/handle/26291389666479894087.
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碩士淡江大學
化學工程與材料工程學系碩士班
93
The study presents a theoretical prediction of the device performance of a sheet-and-tube solar water heater with external recycle, and a comparison of the device performance was made between these two device with and without external recycle. The device with internal fins attached in each tube is also discussed. Analytical results show that the recycle effect can effectively enhance the collector efficiency compared with that in a single-pass device with the same flow rate. The desirable effect of increasing convective transfer rate and the undesirable effect of reducing heat transfer driving force are the two conflict effects produced by the recycle operation. It was found that the convective transfer-rate increment by increasing the recycle ratio could generally compensate for the temperature driving force decrement, leading to improved performance, especially for low flow rate. Also, the collector efficiency increases with increasing collector aspect ratio (i.e., either increasing the tube length or decreasing tube number) for a specified collector area and the distance between tubes.
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Porgar, S., und Nejat Rahmanian. „Investigation of Effect of Aluminium Oxide Nanoparticles on the Thermal Properties of Water-Based Fluids in a Double Tube Heat Exchanger“. 2021. http://hdl.handle.net/10454/18548.
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yesThe thermal behavior of aluminium oxide-water nanofluid in a double pipe carbon steel heat exchanger was investigated in the present study. The overall heat transfer coefficient, Nusselt, and heat transfer coefficient of nanofluid were compared with the base fluid. The volume fraction of the nanoparticles was 1%. By adding nanoparticles to the fluid, the thermal properties of the base fluid improved significantly. The hot and cold fluid flow was considered counter-current, and the nanofluid was pumped into the inner tube and once into the outer tube, and the flow rate of each fluid was 0.05 kg/s. The convective heat transfer and the overall heat transfer coefficient enhanced 94% and 253% for the hot fluid flow in the outer tube and 308 % and 144% for the hot fluid flow in the inner tube, respectively. The pressure drop calculations also showed that the pressure drop would not change significantly when using nanofluid.