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The oscillatory coalescence phenomenon of the Taylor bubble flow subjected to the action of a fluctuating pressure gradient in a pulsating heat pipe was investigated using the front tracking method (FTM). The effects of amplitude and frequency of fluctuating pressure, bubble size, Reynolds number (Re), and Weber number (We) on the bubble coalescence process were studied. The results demonstrated that the lower the pulsation frequency, the longer the period of bubble oscillation, which could provide enough time for bubbles to drain and promoted the coalescence of the bubbles. The larger Euler number (Eu) was, the more easily bubbles coalesced. On the contrary, when Eu was small, the bubbles were slow to coalesce. The size of the top bubble and the bottom bubble had different effects on coalescence. An increase of the length of the top bubble ([L.sub.t]) was beneficial to bubble coalescence while increasing the length of the bottom bubble ([L.sub.b]) restrained bubble coalescence. Time required for bubble coalescence increased with the increase of Re and decreased with increasing We. Key words: oscillating flow, Taylor bubble, pulsating heat pipe, front tracking method, bubble coalescence. Nous utilisons la methode de suivi d'interface (front tracking) (MSI/FTM) pour etudier la coalescence oscillante de bulles de Taylor en mouvement (vertical) soumises a un gradient de pression fluctuant dans un caloduc pulse. Nous examinons les effets de l'amplitude et de la frequence des fluctuations de pression, de la grosseur des bulles, du nombre de Reynolds (Re) et du nombre de Weber (We), sur le mecanisme de coalescence des bulles. Plus la frequence de pulsation est basse, plus grande est la periode d'oscillation des bulles, ce qui peut donner assez de temps aux bulles pour se joindre. Plus le nombre d'Euler (Eu) est eleve, plus la coalescence est facilitee mais, au contraire, lorsque Eu est petit, plus les bulles ont de la difficulte a coalescer rapidement. La grosseur de la bulle superieure et celle de la bulle inferieure ont des effets differents sur la coalescence. L'augmentation de la longueur de la bulle superieure ([L.sub.t]) facilite la coalescence alors que l'augmentation de la longueur de la bulle inferieure ([L.sub.b]) la restreint. Le temps requis pour la coalescence des bulles augmente si Re augmente et diminue si We augmente. [Traduit par la Redaction] Mots-cles : flux oscillant, bulle de Taylor, caloduc pulse, methode de suivi d'interface, coalescence de bulles., 1. Introduction The pulsating flow of Taylor bubbles in pipes is widely seen in natural phenomena and industrial applications, such as, nuclear reactor of ship propulsion systems, rocket low-temperature propellant [...]

Titanium dioxide (Ti[O.sub.2]) nanowires with two different dimensions (i.e., < 100 nm and ~200 nm in diameter) were synthesized and studied under high pressure up to 37 GPa by Raman spectroscopy and synchrotron X-ray diffraction. Direct anatase to baddeleyite phase transitions were observed in both samples upon compression, but with different onset pressures. The observed phase transitions are in contrast to bulk Ti[O.sub.2], where the anatase phase transforms to α-Pb[O.sub.2] phase and then the baddeleyite phase. Compressibility of the anatase and baddeleyite phases was found different than both nanocrystals and the corresponding bulk materials. Our comparative study demonstrated not only that the morphology of Ti[O.sub.2] nanowire substantially influences the high pressure behaviors, but dimensions play a determining role in terms of transformation pressures, phase stability regions, and compressibility. Key words: high pressure, Ti[O.sub.2] nanowires, phase transformation, Raman spectroscopy, synchrotron radiation. Resume: Des nanofils de dioxyde de titane (Ti[O.sub.2]) de deux dimensions differentes (c.-a-d. de diametres < 100 nm et ~200 nm) ontete synthetises et analyses sous de hautes pressions allant jusqu'a 37 GPa par spectroscopie Raman et diffraction des rayons X synchrotron. Des transitions de phase directes anatase-baddeleyite ont ete observees dans les deux echantillons sous l'effet d'une compression, mais avec une pression exercee differente pour chaque echantillon. Les transitions de phase observees contrastent avec celles du Ti[O.sub.2] brut avec lequel la phase anatase se transforme en une phase α-Pb[O.sub.2] puis en une phase baddeleyite. La compressibilite des phases anatase et baddeleyite s'est averee differente de celle des deux nanocristaux et des materiaux bruts correspondants. Notre etude comparative a montre que non seulement la morphologie du nanofil de Ti[O.sub.2] influe grandement sur les comportements a haute pression mais egalement que leurs dimensions joue un role determinant en ce qui concerne les pressions de transformation, les domaines de stabilite des phases et la compressibilite. [Traduit par la Redaction] Mots-cles: haute pression, nanofils de Ti[O.sub.2], transformation de phase, spectroscopie Raman, rayonnement synchrotron., Introduction Titanium dioxide (Ti[O.sub.2]), or titania, is a well-known semiconductor with a wide band gap. Ti[O.sub.2] exhibits a rich phase diagram including more than seven polymorphs. The most abundant forms, [...]

First-principles calculations have been performed to investigate the structural stability, elastic, lattice dynamic, and thermodynamic properties of [Na.sub.2]Se under high pressure. Our results demonstrate that [Na.sub.2]Se in the antifluorite structure phase keeps dynamically stable until 30 GPa. The elastic constants and thermodynamic quantities under high pressure are also calculated and discussed. PACS Nos.: 62.20.D-, 67.80.de, 05.70.-a. Nous presentons des calculs ab initio pour analyser la stabilite structurale, la dynamique de reseau et les proprietes thermodynamiques du compose [Na.sub.2]Se sous haute pression. Nos resultats montrent que le [Na.sub.2]Se, dans la structure de phase anti-fluorine, demeure dynamiquement stable jusqu'a 30 GPa. Nous calculons et analysons les constantes elastiques et thermodynamiques sous haute pression. [Traduit par la Redaction], 1. Introduction Sodium chalcogenide compounds [Na.sub.2]S, [Na.sub.2]Se, and [Na.sub.2]Te, also crystallize in the cubic antifluorite structure (anti-CaF2 type; No 225) at ambient conditions. They have attracted increasing research interest as [...]

Seven Fourier transform spectra of the [v.sub.3] band of oxirane (ethylene oxide) have been recorded with different pressures and used to derive individual line intensities. These line intensities were satisfactorily fit leading to accurate transition moment constants. An atlas of line positions and intensities has been generated. PACS No.: 33.30.Ea. Nous avons enregistre sept spectres a transformee de Fourier de la bande [v.sub.3] d'oxirane (oxyde d'ethylene) a differentes pressions et avons utilise les resultats pour en deduire les intensites individuelles de raie. La modelisation de ces intensites s'est fait avec satisfaction, menant a des valeurs precises des constantes de moment de transition. Nous presentons un atlas de position des raies et de leur intensite., 1. Introduction In a previous paper [1] an extensive analysis of the vibrational bands, [v.sub.15], [v.sub.12], [v.sub.5], [v.sub.3], [v.sub.10], and [v.sub.2] of oxirane was carried out. The upper state ro-vibrational [...]

This paper examines the effect of tire footprint and contact stress distribution under various combinations of tire pressures and tire loads on the pavement response through 3-D finite element static analysis with linear elastic material model. Analyzed footprints include a field-measured footprint and two cases of simplified ones. Our results indicate that factors including tire load, the distribution of contact stress, and the shape of footprint will affect the tensile strains at the bottom of the asphalt concrete layer as well as the compressive strains on the top of the subgrade. However, the compressive strains on the top of the subgrade are more sensitive to tire load than the shape of footprint. The research demonstrated that pavement response analysis could be carried out using field-measured footprints instead of the simplified approximations. Reduced tire pressure was effective in reducing the tensile strains at the bottom of asphalt concrete layer, but did not decrease significantly the compressive strains at the top of the subgrade. Key words: tire-pavement contact stress, tire footprint, tire pressure, pavement response, asphalt concrete pavement, strain, finite element analysis. Le present article etudie l'effet de l'empreinte des pneus et de la distribution de la contrainte de contact selon diverses combinaisons de pressions et de charges de pneus sur la reponse de la chaussee au moyen d'une analyse statique tridimensionnelle par elements finis selon une modelisation elastique lineaire du materiau. Les empreintes analysees comprennent une empreinte mesuree sur le terrain et deux cas d'empreintes simplifiees. Nos resultats indiquent que les facteurs telles la charge du pneu, la distribution de la contrainte de contact et la forme de l'empreinte auront un effet sur la contrainte de tension au bas de la couche de beton bitumineux et sur les contraintes de deformation sur le dessus de la couche de fondation. Toutefois, les contraintes de deformation sur le dessus de la couche de fondation sont plus sensibles a la charge du pneu qu'a la forme de l'empreinte. La recherche a demontre que l'analyse de la reponse de la chaussee pourrait etre realisee en utilisant des empreintes mesurees sur le terrain plutot que des approximations simplifiees. Une pression de pneu reduite a permis de reduire les contraintes de tension au bas de la couche de beton bitumineux, mais n'a pas reduit de maniere significative les contraintes de deformation sur le dessus de la couche de fondation. [Traduit par la Redaction] Mots-cles : contrainte de contact pneu-chaussee, empreinte de pneus, pression de pneu, reponse de la chaussee, chaussee en beton bitumineux, contrainte, analyse par elements finis., 1. Introduction The critical pavement damage mechanisms in flexible pavements are fatigue cracking in the asphalt concrete (AC) layer and rutting in the subgrade (Huang 1993). Fatigue cracking develops in [...]

We consider the universe as a huge [v.sub.R]-sphere formed with degenerate relic neutrinos and suggest that its constant energy density play a role of an effective cosmological constant. We construct the sphere as a bubble of true vacuum in a field theory model with a spontaneously broken U(1) global symmetry, and we interpret the sphere-forming time as the transition time for recent acceleration of the universe. The coincidence problem may be regarded as naturally resolved in this model, because the relic neutrinos can make the [v.sub.R]-sphere at the recent past time during the matter-dominated era. PACS Nos.: 98.80.-k, 95.36.+X, 14.60.St. Nous envisageons l'univers comme une enorme sphere [v.sub.R] formee avec un reliquat de neutrinos degeneres et suggerons que sa densite d'energie constante joue le role d'une constante cosmologique effective. Nous construisons la sphere comme une bulle du vrai vide d'une theorie de champs a symetrie globale U(1) spontanement brisee et nous interpretons le temps de formation de la sphere comme le temps de transition vers la recente acceleration de l'univers. On peut voir le probleme de la coincidence comme resolu de lui-meme dans ce modele, parce que le reliquat de neutrinos peut former la sphere [v.sub.R] du passe recent de l'ere dominee par la matiere. [Traduit par la Redaction], 1. Introduction The inflationary big bang cosmology has been developed into a precision science by recent cosmological observations including supernova data [1] and measurements of cosmic microwave background radiation [2]. [...]

The present paper reports the structural stability, pressure-induced phase transition, and thermophysical properties for refractory metal nitrides (viz: TiN, ZrN, HfN, VN, NbN, and TaN) computed using a three-body force potential model. The structural phase transitions from a parental NaCl (B1) type phase to the most stable CsCl (B2) type phase has been observed in the pressure range 162-370 GPa. Study includes the computation of thermophysical properties (U, f, [θ.sub.D], [v.sub.0], γ, β, [α.sub.V]/[C.sub.V]), where some of the properties are being reported for the first time on these materials. PACS Nos.: 64.70.K-, 81.30.-t, 63.70.+h, 65.40.Ba, 65.60.+a, 81.05.Je. Nous utilisons ici le modele du potentiel a trois corps pour etudier la transition de phase induite par la pression et les proprietes thermo-physiques des nitrures metalliques refractaires, TiN, ZrN, HfN, VN, NbN et TaN. Nous avons observe la transition de phase structurale, de la phase parentale de type NaCl (B1) vers la phase plus stable de type CsCl (B2), dans le domaine de pression allant de 162 a 370 GPa. L'etude inclut le calcul des proprietes thermo-physiques (U, f, [θ.sub.D], [v.sub.0], γ, β, [α.sub.V]/[C.sub.V]) ou certaines de ces quantites apparaissent sous presse pour la premiere fois. [Traduit par la Redaction], 1. Introduction Refractory metal nitrides (RMNs) have become an important research topic over the past few decades. These RMNs have attracted attention, not merely because of their numerous technological applications, [...]

A processing technology that facilitates quality injection molding without prior drying of polymer pellets has been proposed. The main idea is not to let the water evaporate to bubbles inside the mold. The polymer will be maintained hydrated as it was in the hopper of the injection molding machine throughout the entire molding processes by controlling the cavity pressure above the saturation pressure of water until solidified. In this work, the gas counter pressure (GGP) system has been designed and built to maintain the cavity pressure above the saturation pressure. The performance of the proposed method has been examined by checking the visual quality and the mechanical properties of the molded parts. The method has been tested with pellets of polymethyl methacrylate (PMMA), polycarbonate, polyethylene terephthalate, polybutylene terephthalate, and polyamide 66. The results show that the GCP prevents surface impairment incurred by the vapors without or with minor effects on the mechanical properties. Finally, the effects of energy saving has been examined by conducting the actual process for 1 day. POLYM. ENG. SCI., 52:2417-2423, 2012. © 2012 Society of Plastics Engineers, INTRODUCTION A variety of polymer parts are manufactured by the injection molding process (1). These days, the injection molding industry is struggling with cost-down and quality improvement at the same [...]

A calculation method for the active earth pressure on the possibly inclined face of a retaining wall provided with a drainage system along the soil-structure interface is presented. The soil is cohesionless and fully saturated to the ground surface. This situation may arise during heavy rainstorms. To solve the problem, the water seepage through the soil is first analyzed using a numerical procedure based on the boundary element method. Then, the obtained pore-water pressure is used in a Coulomb-type formulation, which supposes a plane failure surface inside the backfill when the wall movement is enough to put the soil mass in the active state. The formulation provides coefficients of active pressure with seepage effect which can be used to evaluate the active earth thrust on walls of any height. A series of charts with values of the coefficients of active earth pressure with seepage calculated for selected values of the soil internal friction angle, the wall-soil friction angle, and the wall face inclination is presented. Key words: earth pressure, seepage, retaining walls, limit equilibrium methods, numerical methods, boundary element method. Cet article presente une methode de calcul de la pression active des terres sur une face possiblement inclinee d'un mur de soutenement ayant un systeme de drainage le long de l'interface sol-structure. Le sol est sans cohesion et completement sature a sa surface. Cette situation peut se produire lors de precipitations abondantes. Pour resoudre ce probleme, l'ecoulement de l'eau a travers le sol est d'abord analyse a l'aide d'une procedure numerique basee sur la methode de l'element frontiere. Ensuite, la pression interstitielle obtenue est utilisee dans une formulation de type Coulomb, qui suppose une surface de rupture plane a l'interieur du remblai lorsque le mouvement du mur est suffisant pour mettre la masse de sol dans un etat actif. La formulation permet d'obtenir des coefficients de pression active avec l'effet de l'ecoulement qui peuvent etre utilises pour evaluer la poussee active des terres sur des murs de n'importe quelle hauteur. Une serie de chartes avec des valeurs de coefficients de pression active des terres avec ecoulement calcules pour des valeurs selectionnees d'angle de friction interne du sol, d'angle de friction mur-sol, et d'inclinaison de la face du mur, sont presentees. Mots-cles : pression des terres, ecoulement, murs de soutenement, methodes d'equilibre limite, methodes numeriques, methode de l' element frontiere. [Traduit par la Redaction], Introduction The determination of active earth pressures on earth retaining structures is routinely performed with methods based on Coulomb (1776) and Rankine (1857) theories, despite the heavy simplifications assumed in [...]

This paper presents the results of a study on the behavior of three full-scale confined masonry walls subjected to combined axial loads and out-of-plane uniform pressures. The variable studied was the wall axial load. Analytical models were developed to predict out-of-plane cracking and maximum pressures. The former was predicted using the finite element method and the latter using the spring-strut method. This last method was modified to include the effect of the wall axial load. Experimental cracking and maximum pressures were compared with those obtained from analytical models. Based on the experimental results, it was concluded that as the axial load increases, the out-of-plane maximum pressure also increases. However, this latter value is limited by crushing of the masonry. By comparing experimental and analytical results, it was concluded that the out-of-plane cracking and maximum pressures are in general well predicted by the analytical models developed in this work. Key words: confined masonry, out-of-plane uniform pressure, axial load, spring-strut method, stiffness of confining elements. Cet article presente les resultats d'une etude sur le comportement de trois murs pleine grandeur en maconnerie confinee soumis a des charges axiales combinees et a des pressions uniformes hors plan. La variable a l'etude etait la charge axiale des murs. Des modeles analytiques ont ete developpes afin de predire la fissuration hors plan et les pressions maximales. La fissuration a ete predite par elements finis et les pressions ont ete predites en utilisant la methode des << amortisseurs >>. Cette methode a ete modifiee pour inclure l'effet de la charge axiale des murs. La fissuration et les pressions maximales des experiences ont ete comparees a celles obtenues a partir de modeles analytiques. Les conclusions basees sur les resultats experimentaux montraient que la pression maximale hors plan augmente avec l'augmentation de la charge axiale. Toutefois, cette augmentation est limitee par l'ecrasement de la maconnerie. En comparant les resultats experimentaux et analytiques, il a ete conclu que la fissuration hors plan et les pressions maximales sont, regle generale, bien predites par les modeles analytiques developpes dans le present travail. Mots-cles : maconnerie confinee, pression uniforme hors plan, charge axiale, methode des << amortisseurs >>, rigidite des elements de confinement. [Traduit par la Redaction], Introduction The behavior of confined masonry walls under out-of-plane uniform pressure has not been widely studied. Most of the effort to study out-of-plane behavior has focused on unreinforced walls (Drysdale [...]

In this study, we consider a charged anisotropic fluid cylinder with no external pressure acting on the fluid. This is a cylindrical version of Krori and Barua's method to explore the field equations with an anisotropic fluid. We discuss models with positive matter density and pressure that satisfy all of the energy and stability conditions. It is found that charge does not vanish at the center of the cylinder. The equilibrium condition as well as the physical conditions are discussed. Further, we highlight the connection between our solutions and charged strange quark stars and dark matter including charged massive particles. A graphical analysis of the matter variables versus charge is given, which indicates a physically reasonable matter distribution. PACS Nos: 04.40.Nr, 04.40.Dg, 04.20.Jb Nous considerons un cylindre de fluide anisotrope charge, sans pression exterieure agissant sur le fluide. Ceci est la version cylindrique de la methode de Krori et Barua pour explorer les equations de champ et les fluides anisotropes. Nous etudions des modeles avec densite de matiere et pression positives qui satisfont toutes les conditions d'energie et de stabilite. Nous trouvons que la charge n'est pas nulle au centre du cylindre. De plus, nous soulignons la connexion entre notre solution et les etoiles a quarks (etranges) chargees, ainsi qu'avec la matiere sombre, incluant les particules massives chargees. L'analyse graphique des variables de matiere obtenues en fonction de la charge indique une distribution de matiere physiquement raisonnable. [Traduit par la Redaction], 1. Introduction The study of general relativistic charged compact objects is of fundamental importance in astrophysics. Strong magnetic fields, different kinds of phase transitions, and solid stellar cores cause anisotropy [...]

Several studies have been carried out on the evaluation of wind-induced pressures on building envelopes. However, there is very limited research on wind-induced forces on the main structural elements of a building including its foundation. Thus, a full-scale monitoring research project was initiated to examine the wind-induced structural forces for a lowrise wood building. The field facilities include two weather stations and a test house equipped with load and pressure sensors. The house is resting on top of twenty-seven 3-axis load cells and is structurally isolated, i.e., the only points of contact between the foundation wall and the superstructure are the load cells. Simultaneously to the load monitoring, 40 pressure taps are recording the envelope pressures both on the roof and the wall surfaces. In addition to the field monitoring, a scaled model of the house was tested in a boundary layer wind tunnel using three different upstream terrain configurations that provided varying levels of turbulence characteristics suitable for comparisons with full-scale values. The analysis of the wind speed and direction field data confirmed the non-uniform variation of the basic terrain properties over the wind direction and this was also verified in the comparison of the field with the wind tunnel results. These comparisons were made in the form of both envelope pressures and total uplift forces at the foundation level and provided useful insight regarding the wind load path inside the structural elements of the building. Experimental findings were also compared to the Canadian Code and American Standard wind provisions and indicated an underestimation of the total uplift force when using the code and standard provisions in some cases. Key words: full-scale monitoring, wind tunnel experiments, low-rise wood building, envelope pressures, wind uplift forces, design implications. De nombreuses etudes sur l'evaluation des charges dues au vent sur les enveloppes de batiments ont ete realisees. Toutefois, tres peu de recherche a ete realisee sur les charges dues au vent sur les elements structuraux principaux d'un batiment, incluant sa fondation. Un projet de recherche a pleine echelle a donc ete entrepris pour examiner les charges structurales dues au vent sur un batiment en bois de faible hauteur. Les installations sur le terrain comprennent deux stations meteorologiques et un batiment d'essai muni de capteurs de charge et de pression. Le batiment d'essai est installe sur 27 cellules de charge triaxiales et est structurellement isole, c.-a-d. que les seuls points de contact entre le mur de fondation et la superstructure sont les cellules de charge. Quarante prises de pression enregistraient en meme temps les pressions sur l'enveloppe, soit sur le toit et sur les murs. En plus du suivi sur le terrain, un modele a l'echelle du batiment a ete mis a l'epreuve dans une soufflerie a couche limite en utilisant trois differentes configurations de terrain amont qui fournissaient divers niveaux de turbulence pouvant etre compares aux valeurs a pleine echelle. L' analyse de la vitesse et de la direction du vent sur le terrain a confirme la variation non uniforme des proprietes de terrain de base par rapport a la direction du vent; cela se verifie egalement lors de la comparaison des resultats sur le terrain et en soufflerie. Ces comparaisons ont ete realisees sous forme de pressions sur l'enveloppe et les forces totales de soulevement au niveau de la fondation et elles ont fourni un apercu utile du chemin de la charge due au vent a l' interieur des elements de structure du batiment. Les conclusions de l' experience ont aussi ete comparees aux dispositions concernant le vent dans le Code canadien et de la norme americaine et elles montrent une sous-estimation de la force totale de soulevement dans certains cas utilisant les dispositions concernant le vent dans le Code canadien et de la norme americaine. Mots-cles : suivi a pleine echelle, experiences en soufflerie, batiment en bois de faible hauteur, pressions sur les enveloppes, forces de soulevement dues au vent, consequences de la conception. [Traduit par la Redaction], 1. Introduction The majority of dwellings in North America are lightweight, low-rise structures of rather simple geometry and layout. Wind-induced loading is of major importance during the design of these [...]

Although several induced trench field instrumentations have been reported in the literature, none have been for twin culverts. This paper describes a field instrumentation of twin 3660 mm inside diameter concrete culverts installed in an induced trench under 21.7 m of fill. Earth pressures were measured at the crown, shoulder, springline, haunch, and invert locations. Average earth pressures measured at the crown and springline were 0.67 and 0.32 times the overburden, respectively. Due to the large culvert size, proper compaction in the haunch regions was not achieved and the bedding was lightly compacted for constructability reasons. These factors resulted in high earth pressures at the inverts (greater than approximately 1400 kPa) and low pressures at the haunches (32-165 kPa). Numerical modelling was used to determine a vertical earth load of 0.87 times the soil prism load. The twin induced trench condition resulted in vertical earth loads 6% higher and 30% lower than the single induced trench and twin positive projecting conditions, respectively. The induced trench method therefore appears to be a viable installation option for large-diameter twin culverts, provided that issues related to bedding and constructability are addressed. Key words: induced trench, field instrumentation, twin culverts, soil-structure interaction, numerical modelling. Plusieurs travaux d'instrumentation de tranchees induites sur le terrain ont ete rapportes dans la litterature; cependant, aucun n'implique des ponceaux doubles. Cet article decrit l'instrumentation de ponceaux doubles de 3660 mm de diameter faits de beton, installes dans une tranchee induite sous 21,7 m de remblai. Les pressions des terres ont ete mesurees au sommet, a l'epaulement, a la ligne de tombee, au gousset et au radier. Les pressions des terres moyennes mesurees au sommet et a la ligne de tombee etaient de 0,67 et 0,32 fois le mort-terrain, respectivement. En raison de la grande dimension du ponceau, la compaction dans les regions de l' epaulement n' a pas ete faite de facon optimale et l' assise a ete compactee legerement pour une bonne constructibilite. Ces facteurs ont entrame des pressions des terres elevees aux raiders (plus de 1400 kPa, approximativement) et faibles aux goussets (32 a 165 kPa). Des modelisations numeriques ont ete realisees pour determiner une charge des terres verticale de 0,87 fois la charge du prisme de sol. La condition de ponceau double dans une tranchee induite cause des charges des terres 6 % plus elevees que le ponceau simple dans une tranchee induite, et 30 % plus faibles que le ponceau double projete. La methode de tranchee induite apparait donc comme une option d'installation viable pour des ponceaux doubles a grand diametre, en supposant que les precautions concernant l'assise et la constructibilite sont prises. Mots-cles : tranchee induite, instrumentation sur le terrain, ponceaux doubles, interaction sol-structure, modelisation numerique. [Traduit par la Redaction], Introduction Although twin culverts are often preferred to meet the hydraulic and environmental requirements of watercourse crossings, minimal work has been done to evaluate the earth pressures and loads they [...]

A three-dimensional (3D) numerical implementation of the limit analysis upper-bound theorem is used to determine passive horizontal earth-pressure coefficients. An extension technique allowing determination of the 3D passive earth pressures for any width-to-height ratios greater than 7 is presented. The horizontal passive earth-pressure coefficients are presented and compared with solutions published previously. Results of the ratio between the 3D and two-dimensional horizontal passive earth-pressure coefficients are shown and found to be almost independent of the soil-to-wall friction ratio. A simple equation is proposed for calculating this passive earth-pressure ratio. Key words: three-dimensional passive earth-pressure coefficients, upper-bound numerical analysis, finite elements. Une application numerique en trois dimensions (3D) du theoreme cinematique de l'analyse limite est utilisee pour determiner les coefficients horizontaux de butee. Une technique d'extension, qui permet de determiner les pressions de butee en 3D pour des ratios de largeur sur hauteur de plus de 7, est presentee. Les coefficients horizontaux de butee sont presentes et compares avec des solutions deja publiees. Les resultats des ratios entre les coefficients horizontaux de butee en 3D et en deux dimensions sont montres et sont presque independants du frottement sol-mur. Une equation simple est proposee pour calculer ce ratio de butee. Mots-cles: coefficients de butee en trois dimensions, analyse numerique a l'approche cinematique, elements finis. [Traduit par la Redaction], Introduction Determination of passive earth pressures is a classical soil mechanics problem. Under two-dimensional (2D) conditions, it has been approached by several authors and methodologies, such as limit equilibrium (Coulomb [...]

In this paper, a three-dimensional (3D) finite element (FE) model is developed to simulate the pullout behaviour of a soil nail in a soil-nail pullout box under different overburden and grouting pressures. The FE model simulates all the procedures of a pullout test on a grouted soil nail in a compacted and saturated completely decomposed granite (CDG) soil. The stress-strain behaviour of the CDG soil is described by a modified Drucker-Prager/Cap model, while that of the soil-nail interface is represented by the Coulomb friction model. Triaxial experiment data are used to calibrate the soil parameters in the soil constitutive model. The interface parameters are determined from back-analysis with the laboratory soil-nail pullout data. The soil stress variations surrounding the soil nail during drilling, grouting, saturation, and pullout are all well simulated by the FE modelling and compared with available test data. The comparisons between the modelling and experimental data have shown that the established FE can well simulate the pullout behaviour of a soil nail in a soil mass. Based on this, the verified FE model has the potential to simulate the performance of a soil nail in a field soil slope. Key words: soil nailing, pull-out resistance, finite element, overburden pressure, grouting pressure, slope. Dans cet article, un modele tridimensionnel par elements finis (EF) est developpe dans le but de simuler le comportement en retrait d'un clou de sol dans une boite de retrait de clou de sol sous differentes pressions des terres et pressions de cimentation. Le modele EF simule toutes les procedures d'un essai de retrait sur un clou de sol cimente dans un sol de granite compacte et completement decompose (GCD). Le comportement en contrainte-deformation du sol GCD est decrit a l' aide du modele Drucker-Prager/Cap modifie, tandis que l' interface sol-clou est representee par le modele de friction de Coulomb. Des donnees d' essais triaxiaux sont utilisees pour calibrer les parametres du sol dans le modele constitutif du sol. Les parametres de l' interface sont determines par retro-analyse des donnees des essais de retrait des clous de sol realises en laboratoire. Les variations des contraintes du sol entourant le clou durant le forage, la cimentation, la saturation et le retrait sont toutes bien simulees par la modelisation EF et se comparent bien aux donnees d'essais disponibles. Les comparaisons entre la modelisation et les donnees experimentales ont demontre que le modele EF etabli peut bien simuler le retrait d'un clou de sol d'une masse de sol. Ainsi, le modele EF verifie a le potentiel de simuler la performance d'un clou de sol dans une pente sur le terrain. Mots-cles : clou de sol, resistance au retrait, elements finis, pression des terres, pression de cimentation, pente. [Traduit par la Redaction], Introduction Grouted soil nails have been widely used in Hong Kong as an economical and efficient method to stabilize existing and new-cut slopes. More than 200 slopes and retaining walls [...]

[1] An integrated structural, petrological, and geochronological/thermochronological study was undertaken to constrain the tectonic controls on the exhumation of the Voltri Massif high-pressure (HP) complex, located in the Ligurian portion of the Western Alps (Italy). Petrotextural analyses were performed to identify the pressure-temperature interval of (I) peak metamorphism (the [D.sub.1]-[M.sub.1] stage) to eclogitic/blueschist facies conditions and (2) the main retrogressive event (the [D.sub.2]-[M.sub.2] stage) to greenschist facies conditions. U-Pb SHRIMP dating on a zircon rim (33.8 [+ or -] 0.8 Ma) and titanite grains (29 [+ or -] 5 Ma), coupled with [sup.40]Ar-[sup.39]Ar analyses on phengite (~64 Ma to ~34 Ma) placed temporal constraints on the exhumation path from the [D.sub.1]-[M.sub.1] to the [D.sub.2]-[M.sub.2] stages at the Eocene-Oligocene boundary. Apatite fission track thermochronology, with older ages of 23.9 [+ or -]4.9 Ma, confirms the existence of a regional, Late Oligocene to Miocene cooling/exhumation event for the Voltri Massif (the [D.sub.3] - [M.sub.3] stage). The compilation of this pressure-temperature-deformation-time path supports a change in the exhumation history: (1) an initial stage, from the [D.sub.1] -[M.sub.1] to the [D.sub.2] -[M.sub.2], which was nearly isothermal with highly variable exhumation rates, and (2) a second stage, from [D.sub.2] -[M.sub.2] to upper crustal levels, which was accomplished by coolinlg and moderate exhumation rates of-1-2 mm yr-. This two-stage path can be reconciled with the dominant tectonic mechanisms responsible for exhumation of HP rocks in the Voltri Massif area. At the regional scale, this path is consistent with major geodynamic reorganization in the Mediterranean region at the Eocene-Oligocene time boundary, which involved a switch from synorogenic events during transpressive kinematics at the Alpine-Apennine plate boundaries, to postorogenic processes related to crustal thinning and opening of back-arc basins. Citation: Vignaroli, G., F. Rossetti, D. Rubatto, T. Theye, F. Lisker, and D. Phillips (2010), Pressure-temperature-deformation-time (P-T-d-t) exhumation history of the Voltri Massif HP complex, Ligurian Alps, Italy, Tectonics, 29, TC6009, doi: 10.1029/2009TC002621.

The partial admission technique is widely used to control the output power of turbines. In some cases, it has more merits than full admission. However, additional losses, such as expansion, mixing, or pumping, are generated in partial admission as compared with full admission. Thus, an experiment was conducted in a linear cascade apparatus having a partial admission region in order to investigate the effect of partial admission on a blade row. The admission region was formed by a spouting nozzle installed at the inlet of the linear cascade apparatus. Its cross section was rectangular and its size is 200 x 200 [mm.sup.2]. The tested blade was axial-type and its chord was 200 mm. Nineteen identical blades were applied to the linear cascade for the partial admission experiment. The blades moved along the rotational direction in front of the admission region, and then operating forces and surface pressures on the blades were measured at the steady state. The experiment was conducted at a Reynolds number of 3 x [10.sup.5] based on the chord. The nozzle flow angle was set to 65 deg with a solidity of 1.38 for performance test at the design point. In addition, another two different solidities of 1.25 and 1.67 were applied. From the experimental results, when the solidity was decreased, the maximum rotational force increased but the maximum axial force decreased. [DOI: 10.1115/1.4002468] Keywords: partial admission, turbine operating forces, surface pressure, linear cascade, axial-type blade

Sperm velocity is long known to be an important indicator of sperm quality but without much biophysical theory explaining it. Contact mechanics based modeling was developed here to determine the effects that sperm velocity ([v.sub.s]) and sperm head density ([[rho].sub.s])--which is an indicator of the stiffness of the head, have on the peak sperm-zona pellucida contact pressure ([p.sub.m]) during the early phase of sperm penetration. The modeling identified [v.sub.s] as being more influential on [p.sub.m] compared with the influence that [[rho].sub.s] has, which means that for spermatozoa competing on the same oocyte, greater [v.sub.s] is a more important advantage than higher [[rho].sub.s]. Specifically, [p.sub.m] was more sensitive by a power of 2 to changes in [v.sub.s] than to changes in [[rho].sub.s]. It was further demonstrated that each 0.1 g/cc increase in [[rho].sub.s] (within the physiologically relevant range of 1.3-1.7 g/cc) would be equivalent to just 3% rise in [v.sub.s], indicating again that faster swimming is a better strategy for spermatozoa compared with head stiffening. The modeling hence provided some useful insights regarding sperm biomechanics, which theoretically elucidate the well-recognized importance of sperm velocity measurements as being indicative of sperm quality. [DOI: 10.1115/1.4002857] Keywords: biomechanical cell model, cellular biomechanics, fertilization, motility, sperm quality

Previous biomechanical models of the penis simulated penile erections utilizing 2D geometry, simplified 3D geometry or made inaccurate assumptions altogether. These models designed the shaft of the penis as a one-compartment pressurized vessel fixed at one end when in reality it is a two-compartment pressurized vessel in which the compartments diverge as they enter the body and are fixed at two separate anatomic sites. This study utilizes the more anatomically correct two-compartment penile model to investigate erectile function. Simplified 2D and 3D models of the erect penis were developed using the finite element method with varying anatomical considerations for analyzing structural stresses, axial buckling, and lateral deformation. This study then validated the results by building and testing corresponding physical models. Finally, a more complex and anatomically accurate model of the penis was designed and analyzed. When subject to a lateral force of 0.5 N, the peak equivalent von Mises (EVM) stress in the twocompartment model increased by about 31.62%, while in the one-compartment model, the peak EVM stress increased by as high as 70.11%. The peak EVM stress was 149 kPa in the more complex and anatomically accurate penile model. When the perforated septum was removed, the peak EVM stress increased to 455 kPa. This study verified that there is significant difference between modeling the penis as a two- versus a one-compartment pressurized vessel. When subjected to external forces, a significant advantage was exhibited by two corporal based cavernosal bodies separated by a perforated septum as opposed to one corporal body. This is due to better structural integrity of the tunica albuginea when subjected to external forces. [DOI: 10.1115/1.4002794]

Pressure pulsations, in volumetric compressor manifolds are one of the most important problems occurring in the compressor installations. They cause noise and vibrations, which may result in installation failures. In 2005 DOE USA (Advanced Reciprocating Compression Technology (ARCT), 2005, Final Report SwRI[R] Project No. 18.11052, DOE Award No. DE-FC26-O4NT42269) published a report where pressure pulsations attenuation is named as one of the three most important problems in compressor plants design and operation. Three main approaches of modeling acoustic wave can be named here: one dimensional pipeline modeling with real domain solution and finite difference methods, Helmholtz theory based acoustic model, where complex Fourier transform is used, or finally full computational fluid dynamics ( CFD) multidimensional approach. All of them have limited capabilities. With one dimensional model no real geometry of an oil separator or a damper can be introduced. In the Helmholtz approach apart from the length limit of a pipe, complex geometry requires transmission properties of the element. CFD is the most accurate but very time consuming in both computational time and data preparation for the CFD software. In the present paper, one of the coupling methods is shown with the introduction of transmittance characteristics. The resulting simulation using generalized Helmholtz model shows much better agreement with the experimental results than for the classic Helmholtz modeling. [DOI: 10.1115/1.4001847]

Traditionally, resultant force of lateral earth pressure serves as the basis for design of nearly vertical walls. Conversely, slopes are designed to be internally stable using a factor of safety approach. However, with the availability of heavy facing elements such as gabions, steep slopes are increasingly being constructed. Steep slopes are considered to be unstable unless supported; that is, such slopes require facings to resist lateral earth pressure. Extending Coulomb's formulation to such slopes may not be conservative as a planar slip surface may not be critical. Presented are the results of a formulation to find the resultant lateral force which utilizes a log spiral failure mechanism. Unlike Caquot and Kerisel or Coulomb, the soil-facing interface friction is assumed to act on segments of vertical surface only, thus replicating the geometry of stacked rectangular facing units. Given the batter, the backslope, the height, the interface friction, and the unit weight and design friction angle of the backfill, one can quickly determine the corresponding lateral earth pressure coefficient. Formulation assuming the interface friction is acting on an imaginary surface inclined at the batter angle, essentially equivalent to Coulomb and Caquot and Kerisel, is also presented. Its results show that for batters up to 20[degrees], the common approach of using the Coulomb method, including the assumed interface friction direction to coincide with the batter, yields results that are quite close to those stemming from the log spiral analysis. Hence, use of Coulomb's analysis for such small batters is reasonable as its formulation is simple. However, the lateral resultant is grossly underestimated for larger batters, especially when Coulomb analysis is used. DOI: 10.1061/(ASCE)GT.1943-5606.0000398 CE Database subject headings: Earth pressure; Limit equilibrium; Slope stability. Author keywords: Coulomb; Caquot and Kerisel; Lateral earth pressure; Limit equilibrium; Slope instability.

Performance of a bolted flange joint is characterized mainly due to its 'strength' and 'sealing capability.' A number of analytical and experimental studies have been conducted to study these characteristics only under internal pressure loading. A very limited amount of work is found in the literature under combined internal pressure and bending loading. Due to the ignorance of this external loading, i.e., bending loading, the optimized performance of the bolted flange joint cannot be achieved. The present design codes do not address the effects of bending loading on the structural integrity and sealing ability. To investigate joint strength and sealing capability under combined loading, an extensive comparative experimental and numerical study of a nongasketed flange joint is carried out and overall joint performance and behavior is discussed. Actual joint load capacity is determined under both the design and proof test pressure with maximum additional external bending loading that can be applied for safe joint performance. In addition, as experimentally it is impossible to test different flange joint sizes under combined loading application, hence finite element model developed and verified with the experimental results, presented in this paper can be used as base to study the behavior for different nongasketed flange joint sizes for different classes under combined pressure and bending loading. DOI: 10.1061/(ASCE)EM.1943-7889.0000191 CE Database subject headings: Bolts; Bending; Sealing; Internal pressure. Author keywords: Nongasketed; Combined; Bolt up; Operating; Bending; Sealing.

Inefficient ionization and poor transmission of the charged species produced by an electrospray from the ambient pressure mass spectrometer source into the high vacuum region required for mass analysis significantly limits achievable sensitivity. Here, we present evidence that, when operated at flow rates of 50 nL/min, a new electrospray-based ion source operated at ~20 Torr can deliver ~50% of the analyte ions initially in the solution as charged desolvated species into the rough vacuum region of mass spectrometers. The ion source can be tuned to optimize the analyte signal for readily ionized species while reducing the background contribution. 10.1021/ac1019123

This paper studies the static stability of metal cones subjected to combined, simultaneous action of the external pressure and axial compression. Cones are relatively thick; hence, their buckling performance remains within the elastic-plastic range. The literature review shows that there are very few results within this range and none on combined stability. The current paper aims to fill this gap. Combined stability plot, sometimes called interactive stability plot, is obtained for mild steel models. Most attention is given to buckling caused by a single type of loading, i.e., by hydrostatic external pressure and by axial compression. Asymmetric bifurcation bucklings, collapse load in addition to the first yield pressure and first yield force, are computed using two independent proprietory codes in order to compare predictions given by them. Finally, selected cone configurations are used to verify numerical findings. To this end four cones were computer numerically controlled-machined from a solid steel billet of 252 mm in diameter All cones had integral top and bottom flanges in order to mimic realistic boundary conditions. Computed predictions of buckling loads, caused by external hydrostatic pressure, were close to the experimental values. But similar comparisons for axially compressed cones are not so good. Possible reasons for this disparity are discussed in the paper [DOI: 10.1115/1.4001437] Keywords: buckling, external pressure, axial compression, conical shells

A multi-elbow piping system is adopted for the Japan sodium-cooled fast reactor (JSFR) cold-legs. Flow-induced vibration (FIV) is considered to appear due to complex turbulent flow with very high Reynolds number in the piping. In this study, pressure measurement for a single elbow flow is conducted to elucidate pressure fluctuation characteristics originated from turbulent motion in the elbow, which lead potentially to the FIV. Two different scale models, 1/7- and 1/14-scale simulating the JSFR cold-leg piping, are tested experimentally to confirm whether a scale effect in pressure fluctuation characteristics exists. A distinguishing peak can be seen in each power spectrum density (PSD) profile of pressure fluctuation obtained in and downstream of the flow separation region for both scaled models. When nondimensionalized, the PSD profiles show good correspondence regardless of scale model and even of Reynolds number simulated in this study. [DOI: 10.1115/1.4002813] Keywords: fast reactor, cold-leg piping, elbow flow, flow-induced vibration, flow separation, pressure fluctuation

This brief note reports the results of a set of biaxial experiments on Al-6061-T6 tubes tested to rupture under radial stress paths of combined internal pressure and axial load. The experiments are then simulated with shell-type finite element models, in which several yield functions are calibrated and implemented and their performance evaluated against the experimental results. [DOI: 10.1115/1.4001940]

In this paper, the results of numerical simulation on the performance of a sudden expansion with fence viewed as a diffuser are presented. The two-dimensional steady differential equations for conservation of mass and momentum have been solved using the semi-implicit method for pressure-linked equations (SIMPLE) algorithm. The Reynolds number is in the range of 20-100 and fence subtended angle (FSA) between 10 deg and 30 deg. An aspect ratio of 2 is fixed for all the computations. The effect of each variable on average static pressure and diffuser effectiveness has been studied. Computations have revealed that for higher Reynolds number, the use of a fence always increases the effectiveness of the diffusion process when compared with a simple sudden expansion configuration. In low Reynolds number regime, depending on the positioning of the fence and the fence subtended angle, the fence may increase or decrease the diffuser effectiveness in comparison with sudden expansion without fence. [DOI: 10.1115/1.4000800] Keywords: sudden expansion with fence, Reynolds number, FSA, static pressure, diffuser effectiveness

Thermoacoustic transfer functions of a full-scale gas turbine burner operating under full engine pressure have been measured. The excitation of the high-pressure test facility was done using a siren that modulated a part of the combustion airflow. Pulsation probes have been used to record the acoustic response of the system to this excitation. In addition, the flame's luminescence response was measured by multiple photomultiplier probes and a light spectrometer. Three techniques to obtain the thermoacoustic transfer function are proposed and employed: two acoustic-optical techniques and a purely acoustic technique. The first acoustical-optical technique uses one single optical signal capturing the chemiluminescence intensity of the flame as a measure for the heat release in the flame. This technique only works if heat release fluctuations in the flame have only one generic source, e.g., equivalence ratio or mass flow fluctuations. The second acoustic-optical technique makes use of the different response of the flame's luminescence at different optical wavelengths bands to acoustic excitation. It also works, if the heat release fluctuations have two contributions, e.g., equivalence ratio and mass flow fluctuation. For the purely acoustic technique, a new method was developed in order to obtain the flame transfer function, burner transfer function, and flame source term from only three pressure transducer signals. The purely acoustic method could be validated by the results obtained from the acoustic-optical techniques. The acoustic and acoustic-optical methods have been compared and a discussion on the benefits and limitations of each is given. The measured transfer functions have been implemented into a nonlinear, three-dimensional, time domain network model of a gas turbine with an annular combustion chamber The predicted pulsation behavior shows a good agreement with pulsation measurements on a field gas turbine. [DOI: 10.1115/1.4000854]

Pressure-driven remobilization without an applied electric field is shown to be possible with capillary isoelectric focusing using packed capillaries. The capillary dimensions are 100 [micro]m i.d. and 2 cm in length, and the packing is made of 0.9 [micro]m nonporous silica particles that are chemically modified with a brush layer of polyacrylamide. Both reversible and irreversible adsorption are shown to be negligible. The packed capillaries eliminate the problem of unwanted hydrodynamic flow between reservoirs. Three proteins are focused: trypsin inhibitor, carbonic anhydrase II, and myoglobin. The time required for focusing in the packed capillaries is increased by only a factor of 2 compared to the open capillary, giving complete focusing in less than 15 min at 200 V/cm. The packed capillaries allow the use of higher electric fields, with resolution continually increasing up to at least 1500 V/cm. The packing obstructs diffusional broadening after the field is turned off: for trypsin inhibitor, D - 6.1([+ or -]0.3) x [10.sup.-8] [cm.sup.2]/s for the packed capillary vs D: 28.8([+ or -]0.3) x [10.sup.-8] [cm.sup.2]/s for the open capillary. The broadening contributed by the packing during remobilization is from eddy diffusion, and it is described by its plate height, H, which is the variance per unit length: H = [[sigma].sup.2]/L = 0.64 [micro]m. This limits the resolution to 0.1 pH units for the 2 cm capillary having a pH range of 3 10, giving a theoretical peak capacity of 47. 10.1021/ac101680z

Three-dimensional finite element analyses were performed to study the behavior of piles in sloping ground under undrained lateral loading conditions. Piles of different diameter and length in sloping cohesive soils of different undrained shear strength and several ground slopes were considered. Based on the results of the finite element analyses, analytical formulations are derived for the ultimate load per unit length and the initial stiffness of hyperbolic p-y curves. New p-y criteria for static loading of piles in clay are proposed, which take into account the inclination of the slope and the adhesion of the pile-slope interface. These curves are used through a commercial subgrade reaction computer code to parametrically analyze the effect of slope inclination and pile adhesion on lateral displacements and bending moments. To validate the proposed p-y curves, a number of well documented lateral load tests are analyzed. Remarkable agreement is obtained between predicted and measured responses for a wide range of soil undrained shear strength and pile diameter, length, and stiffness. DOI: 10.1061/(ASCE)GT.1943-5606.0000373 CE Database subject headings: Piles; Lateral loads; Clays; Finite element method; Numerical analysis; Lateral pressure; Soil-pile interactions; Slopes. Author keywords: Piles; Lateral loads; Clays; Finite-element method; Numerical analysis; Lateral pressure; Soil-pile interactions; Slopes; p-y curves; Adhesion.

Observations of the cross-shore variations of pressure gradients measured on a fixed barred beach in a large-scale laboratory wave flume are presented in this paper. The wave-induced components (0.1-1.0 Hz) of the free surface elevation, near- bottom vertical and cross-shore velocities, and pressure gradient are used in the analysis. The cross-shore variation of the pressure gradient showed the maximum value in the area of wave breaking over the bar, and the pressure gradients were considered to be influenced by the fluctuation of the water surface elevation, which are shown to be a rough proxy for the water surface slope. The cross correlation related to the vertical velocity showed no correlation in the wave breaking area. Surprisingly, although several measuring points were located in the wave breaking area or in the inner surf zone, the spatial variation of the pressure gradient and water surface elevation had a correlation coefficient greater than 0.8 with time lags approximately 0.1 of the wave period from offshore to onshore in both regular and irregular wave cases. This indicates that the near-bottom pressure gradient can be estimated using the water surface elevation over a complex barred bathymetry and through the inner surf zone. DOI: 10.1061/(ASCE)WW.1943-5460.0000055 CE Database subject headings: Pressure; Breaking waves; Laboratory tests; Barrier beaches; Surf zone. Author keywords: Pressure; Breaking waves; Laboratory tests; Barrier beaches.

The clarification of creep damage mechanism and the establishment of remaining life prediction methods of longitudinal welded piping of P91 steel are important subjects to maintain a reliable operation of boilers in thermal power plants. Internal pressure creep tests were conducted on P91 steel longitudinal welded tubes to characterize the evolution of creep damage with time and to evaluate a life prediction method. Interrupted creep tests were performed for damage observation in addition to rupture tests. Three dimensional finite element creep analyses of the longitudinal welded tube specimens were conducted to identify the stress and creep strain distributions within the specimen during creep. Failure occurred at a heat affected zone (HAZ) without a significant macroscopic deformation. It was found that the initiation of creep voids had concentrated at the midthickness region in the HAZ rather than in the surface. The creep analysis results indicated that the triaxial tensile stress yielded at the midthickness region in the HAZ due to difference of creep deformation property among the base metal, the HAZ, and the weld metal. It was suggested that the triaxial stress state caused acceleration of the creep damage evolution in the HAZ, resulting in internal failure of the tube specimens. A rupture time prediction method of the welded tube is proposed based on the maximum principal stress and the triaxial stress factor in the HAZ. The void growth behavior in the HAZ was well predicted by the previously proposed void growth simulation method by introducing a void initiation function to the method. [DOI: 10.1115/1.4001688] Keywords: internal pressure creep, P91 steel, longitudinal welded tube, life prediction, void growth simulation

Simple and accurate approaches to predict failure pressures in corroded pipelines are outlined in this work. It is shown that failure pressures for corroded pipelines can be predicted from the solution for undamaged pipelines using an equivalent wall thickness. Three different yield criteria (Tresca, ASSY (average shear stress yield), and von Mises) are reviewed in the light of reported experimental burst pressures. At first, failure pressures for cylindrical vessels with an infinitely long groove are studied by means of numerical simulations. The effect of groove size (depth and width) over the pipeline performance is quantified through a model. Finally, the scheme is extended to estimate the failure pressure of thin walled vessels with irregular finite defects. [DOI: 10.1115/1.4001801] Keywords: failure pressure, infinitely long groove, burst test, damaged and undamaged pipelines

In this paper, the modified formulae have been provided. They can be used to calculate the stress in layers with gaps of a layered cylinder In order to obtain the modified formulae, a detailed derivation process has also been presented in this paper. Meanwhile, we have clarified the derivation process and application range of Pimshtein's formulae and corrected the errors. We have also indicated the shortcomings of the formulae given by Huang, Chen and Lai, and the ASME code. Finally, a practical example is presented to show how the modified formulae are applied. Calculation results obtained from the modified formulae have been compared with those obtained by finite element method and above mentioned formulae; it shows that the results from the modified formulae are in accordance with finite element results. [DOI: 10.1115/1.4001658] Keywords: layered vessel interlayer gaps, modified formulae, stress calculation

A letterbox trailing edge configuration is formed by adding flow partitions to a gill slot or pressure side cutback. Letterbox partitions are a common trailing edge configuration for vanes and blades, and the aerodynamics of these configurations are consequently of interest. Exit surveys detailing total pressure loss, turning angle, and secondary velocities have been acquired for a vane with letterbox partitions in a large-scale low speed cascade facility. These measurements are compared with exit surveys of both the base (solid) and gill slot vane configurations. Exit surveys have been taken over a four to one range in chord Reynolds numbers (500,000, 1,000,000, and 2,000,000) based on exit conditions and for low (0.7%), grid (8.5%), and aerocombustor (13.5%) turbulence conditions with varying blowing rate (50%, 100%, 150%, and 200% design flow). Exit loss, angle, and secondary velocity measurements were acquired in the facility using a five-hole cone probe at a measuring station representing an axial chord spacing of 0.25 from the vane trailing edge plane. Differences between losses with the base vane, gill slot vane, and letterbox vane for a given turbulence condition and Reynolds number are compared providing evidence of coolant ejection losses, and losses due to the separation off the exit slot lip and partitions. Additionally, differences in the level of losses, distribution of losses, and secondary flow vectors are presented for the different turbulence conditions at the different Reynolds numbers. The letterbox configuration has been found to have slightly reduced losses at a given flow rate compared with the gill slot. However, the letterbox requires an increased pressure drop for the same ejection flow. The present paper together with a related paper (2008, 'Letterbox Trailing Edge Heat Transfer--Effects of Blowing Rate, Reynolds Number, and External Turbulence on Heat Transfer and Film Cooling Effectiveness,' ASME, Paper No. GT2008-50474), which documents letterbox heat transfer, is intended to provide designers with aerodynamic loss and heat transfer information needed for design evaluation and comparison with competing trailing edge designs. [DOI: 10.1115/1.3195035]

A parametric set of velocity distributions has been investigated using a flat-plate experiment. Three different diffusion factors and peak velocity locations were tested. These were designed to mimic the suction surfaces of low pressure (LP) turbine blades. Unsteady wakes, inherent in real turbomachinery flows, were generated using a moving bar mechanism. A turbulence grid generated a freestream turbulence level that is believed to be typical of LP turbines. Measurements were taken across a Reynolds number range 50,000-220,000 at three reduced frequencies (0.314, 0.628, and 0.942). Boundary. layer traverses were performed at the nominal trailing edge using a laser Doppler anemometry system and hot films were used to examine the boundary layer behavior along the surface. For every, velocity distribution tested, the boundary layer separated in the diffusing flow downstream of the peak velocity. The loss production is dominated by the mixing in the reattachment process, mixing in the turbulent boundary layer downstream of reattachment, and the effects of the unsteady interaction between the wakes and the boundary layer. A sensitive balance governs the optimal location of peak velocity on the surface. Moving the velocity peak forward on the blade was found to be increasingly beneficial when bubble-generated losses are high, i.e. at low Reynolds number, at low reduced frequency, and at high diffusion factors. [DOI: 10.1115/1.3192149]

Film-cooling effectiveness is measured on a rotating turbine blade platform for coolant injection through discrete holes using pressure sensitive paint technique. Most of the existing literatures provide information only for stationary endwalls. The effects of rotation on the platform film-cooling effectiveness are not well documented. Hence, the existing three-stage turbine research facility at the Turbomachinery and Flow Performance Laboratory, Texas A&M University was redesigned and installed to enable coolant gas injection on the first stage rotor platform. Two distinct coolant supply loops were incorporated into the rotor to facilitate separate feeds for upstream cooling using stator-rotor gap purge flow and downstream discrete-hole film cooling. As a continuation of the previously published work involving stator-rotor gap purge cooling, this study investigates film-cooling effectiveness on the first stage rotor platform due to coolant gas injection through nine discrete holes located downstream within the passage region. Filmcooling effectiveness is measured for turbine rotor frequencies of 2400 rpm, 2550 rpm, and 3000 rpm corresponding to rotation numbers of [R.sub.o] = 0.18, 0.19, and 0.23, respectively. For each of the turbine rotational frequencies, film-cooling effectiveness is determined for average film-hole blowing ratios Of [M.sub.holes] = 0.5, 0.75, 1.0, 1.25, 1.5, and 2.0. To provide a complete picture of hub cooling under rotating conditions, simultaneous injection of coolant gas through upstream stator-rotor purge gap and downstream discrete film-hole is also studied. The combined tests are conducted for gap purge flow corresponding to coolant to mainstream mass flow ratio of MFR = 1% with three downstream film-hole blowing ratios of [M.sub.holes] = 0.75, 1.0, and 1.25 for each of the three turbine speeds. The results for combined upstream stator-rotor gap purge flow and downstream discrete holes provide information about the optimum purge flow coolant mass, average coolant hole blowing ratios for each rotational speed, and coolant injection location along the passage to obtain efficient platform film cooling. [DOI: 10.1115/1.3142860]

The effect of oxygen partial pressure on crack growth rates in Alloy 617 has been studied using both static and fatigue loadings at 650[degrees]C over the oxygen partial pressure range [10.sup.-19] - [10.sup.-3] atm. Tests were conducted at either the constant stress intensity factor K for static conditions or the constant [DELTA]K in fatigue. Oxygen concentration was measured on both the inlet and outlet of the test retort as well as in situ with a probe located directly at the specimen surface. For fatigue loading the crack path was observed to be transgranular but crystallographic with a decreasing growth rate as the oxygen concentration decreased. However, for static loading the crack path shifted to intergranular at the same [K.sub.max] (fatigue) and exhibited what appears to be an increasing crack growth rate with decreasing oxygen concentration. [DOI: 10.1115/1.3155793]

Surface-pressure fluctuations are measured for the separated flow over a smoothly contoured axisymmetric bump or hill with an approaching two-dimensional turbulent boundary-layer thickness that is half of the bump height and momentum thickness Reynolds number [Re.sub.[theta]] = 7,300. Two piezoresistive pressure transducers were used to measure the pressure fluctuations and to remove the noise by the subtraction method. The flow over this bump shows highly unsteady saddle-focus separations on the leeside curved surface. The magnitude of surface-pressure fluctuations is higher on the leeside than the windward side. The power spectral levels of pressure fluctuations are high in the low-frequency region, and they contribute dominantly to the resulting surface-pressure fluctuation on the leeside. In the separated region, large-scaled eddy structures associated with the streamwise vortices emanated from three-dimensional separations are major sources for the pressure fluctuation generation, and the rapid spectral decay is observed. From the approximate analysis, the asymmetric negative skewed histogram of surface-pressure fluctuations appears in the separated region. DOI: 10.2514/1.J050429

The postcyclic reconsolidation response of low-plastic Fraser River silt was examined using laboratory direct simple shear testing. Specimens of undisturbed and reconstituted natural low-plastic Fraser River silt and reconstituted quartz powder, initially subjected to constant-volume cyclic loading under different cyclic stress ratios (CSRs) and then reconsolidated to their initial effective stresses ([[sigma]'.sub.vo]), were specifically investigated. The volumetric strains during postcyclic reconsolidation ([[epsilon].sub.v.ps]) were noted to generally increase with the maximum cyclic excess pore-water pressure ([DELTA][u.sub.max]) and maximum cyclic shear strain experienced by the specimens during cyclic loading. The values of [[epsilon].sub.v-ps] and maximum cyclic excess pore-water pressure ratio ([r.sub.u-max]) were observed to form a coherent relationship regardless of overconsolidation effects, particle fabric, and initial (precyclic) void ratio of the soil. The specimens with high [r.sub.u-max] suffered significantly higher postcyclic reconsolidation strains; [[epsilon].sub.v-ps] ranging between 1.5 and 5% were noted when [r.sub.u-max] > 0.8. The observed [[epsilon].sub.v-ps] versus [r.sub.u-max] relationship, when used in combination with the observed dependence of cyclic excess pore-water pressure on CSR and number of load cycles, seems to provide a reasonable approach to estimate postcyclic reconsolidation strains of low-plastic silt. DOI: 10.1061/(ASCE)GT.1943-5606.0000349 CE Database subject headings: Shear tests; Soil liquefaction; Earthquakes; Silts; Cyclic loads; Soil consolidation; Pore water; Water pressure; Canada. Author keywords: Direct simple shear testing; Liquefaction; Earthquake response of silts; Cyclic loading; Postcyclic reconsolidation strains.

An experimental and analytical program was designed and conducted to evaluate the magnitude and distribution of seismically induced lateral earth pressures on cantilever retaining structures with dry medium dense sand backfill. Results from two sets of dynamic centrifuge experiments and two-dimensional nonlinear finite-element analyses show that maximum dynamic earth pressures monotonically increase with depth and can be reasonably approximated by a triangular distribution. Moreover, dynamic earth pressures and inertia forces do not act simultaneously on the cantilever retaining walls. As a result, designing cantilever retaining walls for maximum dynamic earth pressure increment and maximum wall inertia, as is the current practice, is overly conservative and does not reflect the true seismic response of the wall-backfill system. The relationship between the seismic earth pressure increment coefficient ([DELTA][K.sub.AE]) at the time of maximum overall wall moment and peak ground acceleration obtained from our experiments suggests that seismic earth pressures on cantilever retaining walls can be neglected at accelerations below 0.4 g. This finding is consistent with the observed good seismic performance of conventionally designed cantilever retaining structures. DOI: 10.1061/(ASCE)GT.1943-5606.0000351 CE Database subject headings: Retaining walls; Earth pressure; Seismic effects; Earthquakes; Centrifuge models; Numerical models; Simulation; Seismic design; Backfills. Author keywords: Retaining walls; Earth pressures; Earthquakes; Centrifuge models; Numerical models; Simulation; Seismic design; Backfills.

This paper presents the numerical computation of a turbulent jet of nitrogen into nitrogen under supercritical pressure. The large-eddy simulation framework for turbulence modeling is used and real-gas effects are accounted for through a cubic equation of state and appropriate viscosity and conductivity coefficients. The purpose of this paper is to evaluate how low-pressure large-eddy simulation equations coupled with real-gas thermodynamics and transport compare with experiments. Although this approach does not take into account the impact of high density gradients and nonlinear thermodynamics on turbulence modeling, the results show reasonable agreement with available experimental data and reveal the importance of numerics for such computations. The simulations indicate a limited influence of the density ratio and the thermodynamic conditions on the jets spreading rate and pseudosimilarity behavior. DOI: 10.2514/1.J050288

A method is proposed to calculate the trailing-edge broadband noise emitted from an airfoil, based on a steady Reynolds-averaged Navier-Stokes solution of the flowfield. For this purpose, the pressure spectrum on the airfoil surface near the trailing edge is calculated using a statistical model from the Reynolds-averaged Navier-Stokes mean velocity and turbulence data in the airfoil boundary layer. The obtained wall-pressure spectrum is used to compute the radiated sound by means of an aeroacoustic analogy, namely, Amiet's theory of airfoil sound. The statistical model for wall-pressure fluctuations is validated with two test cases from the literature, a boundary layer with an adverse pressure gradient, and a flat plate boundary layer without a pressure gradient. The influence of specific model assumptions is studied, such as the convection velocity of pressure-producing structures and the scale anisotropy of boundary-layer turbulence. Furthermore, the influence of the Reynolds-averaged Navier--Stokes simulation on the calculated spectra is investigated using three different turbulence models. The method is finally applied to the case of a Valeo controlled-diffusion airfoil placed in a jet wind tunnel in the anechoic facility of Ecole Centrale de Lyon. Reynolds-averaged Navier--Stokes solutions for this test case are computed with different turbulence models, the wall-pressure spectrum near the trailing edge is calculated using the statistical model, and the radiated noise is computed with Amiet's theory. All intermediate results of the method are compared with experimental data. DOI: 10.2514/1.J050206

Observations on outcrop of a regionally developed sand injectite are used to infer and estimate the pore-pressure conditions in the shallow crust that caused the fluidization and injection of tens of cubic kilometres of sand. The estimated pore-fluid pressures at the base of the injection complex (at 1500 m burial depth, below a regionally developed shale-dominated seal) are from 22.26 to 25.08 MPa, which respectively correspond to 0.81 and 0.95 lithostatic pressure. A theoretical basis for prediction of sand injection is defined and applied to the prediction of pore pressure at the time of sand injection, the depth at which seal failure occurred, and the density and granular content of the fluidized flow. Lateral variations in the style and abundance of sandstone intrusions are described and these all fit into a remarkably uniform tripartite division of parent units, an intrusive complex and an extrusive complex. A sill zone (intrusions are dominated by sills) occurs in a restricted stratigraphic interval 200-270 m thick. Location of the base of the sill zone is directly related to the thickness of the overburden, and an isobaric surface at the time of sand injection, the lithostatic equilibrium surface, is defined at the base of the sill zone. When the sills formed an extended period of supralithostatic pressure occurred within the sill zone. doi: 10.1144/0016-76492010-004.

In this work we have systematically studied the behavior of solenoid pumps (SMP) as a function of flow rate and flow resistance. Using a new, economic, and miniature control unit, we achieved improvements of the systems versatility, transportability, and pressure robustness. A further important improvement with respect to pressure resistance was achieved when a flexible pumping tube was inserted between the solenoid pump and the flow resistance acting as a pressure reservoir and pulsation damper. The experimental data were compared with two pressure pulse models for SMP, which were developed during this work and which were well-suited to describe the SMP operation. 10.1021/ac101250h

A simple semi-empirical model for predicting the peak overpressure field that results when a shock emerges from a circular shock tube is presented and validated. By assuming that the shape of the expanding shock remains geometrically similar after an initial development period, an equation that describes the peak overpressure field in the horizontal plane containing the shock tube's centerline was developed. The accuracy of this equation was evaluated experimentally by collecting peak overpressure field measurements along radials from the shock tube exit at 0 deg, 45 deg, and 90 deg over a range of shock Mach numbers from 1.15 to 1.45. It was found that the equation became more accurate at higher Mach numbers with percent differences between experimental measurements and theoretical predictions ranging from 1.1% to 3.6% over the range of Mach numbers considered. (1) Shocks do propagate in a geometrically similar manner after some initial development length over the range of Mach numbers considered here. (2) The model developed here gives reasonable predictions for the overpressure field from a shock emerging from a circular shock tube. (3) Shocks are expected to be completely symmetric with respect to the shock tube's centerline, and hence, a three dimensional overpressure field may be predicted by the model developed here. (4) While there is a range of polar angle at which the shock shape may be described as being spherical with respect to the shock tube's exit, this range does not encompass the entirety of the half space in front of the shock tube, and the model developed here is needed to accurately describe the entire peak overpressure field. [DOI: 10.1115/1.4002183] Keywords: shock tube, pressure field, semi-empirical