Littérature scientifique sur le sujet « Wall Quality Index »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Wall Quality Index ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Articles de revues sur le sujet "Wall Quality Index"
1
Borri, Antonio, Marco Corradi et Alessandro De Maria. « The Failure of Masonry Walls by Disaggregation and the Masonry Quality Index ». Heritage 3, no 4 (22 octobre 2020) : 1162–98. http://dx.doi.org/10.3390/heritage3040065.
Texte intégralRésumé :
The visual method for assessment of the structural behaviour of historic masonry walls, known by the acronym MQI (Masonry Quality Index) was introduced in 2002 by a team of researchers from the University of Perugia, Italy. This is based on a visual survey of the faces and the cross section of a wall panel, and it aims at verifying if a wall complies with the “rules of the art”. Based on this analysis, it is possible to calculate a numerical index: numerous tests, carried out on site by the authors to validate the method, have demonstrated that the index is able to provide useful information about the mechanical characteristics and structural response, in general, of the analysed wall panel. The failure mode of a wall panel under the action of an earthquake is a critical aspect. In general, the failure modes can be categorized in two classes: masonry disaggregation and the development of a local or global mechanism of wall elements (macroelements). Several theoretical models and numerical simulations only consider the latter. In this paper, application of the MQI method is further investigated, with particular emphasis to those masonry typologies which are more prone to collapse by disaggregation during a seismic event. Under the action of an earthquake, some types of masonry are typically unable to deform and to split in macroelements, and another type of failure occurs: this is the so-called “masonry disaggregation” or “masonry crumbling”. This type of failure anticipates the ones resulting from macroelement methods or stress analysis. As a conclusion, these latter methods become completely inappropriate and potentially hazardous, as they overestimate the seismic capacity of the building under investigation. The MQI method has been adapted to assess the structural response of different types of masonry under the action of an earthquake. In detail, the aim was to verify when the phenomenon of masonry disaggregation is likely to occur.
2
Nguyen, Quoc, et Dimitrios Papavassiliou. « Quality Measures of Mixing in Turbulent Flow and Effects of Molecular Diffusivity ». Fluids 3, no 3 (30 juillet 2018) : 53. http://dx.doi.org/10.3390/fluids3030053.
Texte intégralRésumé :
Results from numerical simulations of the mixing of two puffs of scalars released in a turbulent flow channel are used to introduce a measure of mixing quality, and to investigate the effectiveness of turbulent mixing as a function of the location of the puff release and the molecular diffusivity of the puffs. The puffs are released from instantaneous line sources in the flow field with Schmidt numbers that range from 0.7 to 2400. The line sources are located at different distances from the channel wall, starting from the wall itself, the viscous wall layer, the logarithmic layer, and the channel center. The mixing effectiveness is quantified by following the trajectories of individual particles with a Lagrangian approach and carefully counting the number of particles from both puffs that arrive at different locations in the flow field as a function of time. A new measure, the mixing quality index Ø, is defined as the product of the normalized fraction of particles from the two puffs at a flow location. The mixing quality index can take values from 0, corresponding to no mixing, to 0.25, corresponding to full mixing. The mixing quality in the flow is found to depend on the Schmidt number of the puffs when the two puffs are released in the viscous wall region, while the Schmidt number is not important for the mixing of puffs released outside the logarithmic region.
3
Bao, Xue Fang. « Human Resident Acoustical Environment and Acoustical Insulation of Residential Building ». Applied Mechanics and Materials 368-370 (août 2013) : 435–40. http://dx.doi.org/10.4028/www.scientific.net/amm.368-370.435.
Texte intégralRésumé :
The development of economytraffic and industry have brought worse noise-pollution of city residences environment,the human residing acoustical environment quality is getting worse ,the development of green residential acoustical environment is extremely urgent .Dwelling houses sound insulation ability is one of important index of its quality. This text aim at the sound insulation problem because of light-weight wall being used at large, analyze the principle of sound insulation and optimize it ,briefly introduce the construction project of dwelling house sound insulation of light-weight wall by experiment contrast, expatiate on the technology measure of improving performance of light-weight wall.
4
Mckenzie, Kirsty M., Reeja Nasir, Yang Kong, Hasthi U. Dissanayake, Rowena McMullan, Adrienne Gordon, Alice Meroni, Melinda Phang et Michael R. Skilton. « Maternal Dietary Carbohydrate Intake and Newborn Aortic Wall Thickness ». Nutrients 13, no 4 (20 avril 2021) : 1382. http://dx.doi.org/10.3390/nu13041382.
Texte intégralRésumé :
Evidence from animal models indicates that maternal diet during pregnancy affects offspring cardiometabolic health. Improving carbohydrate quality during high-risk pregnancies reduces aortic intima-medial thickness; a marker for early atherosclerosis; in the infant offspring. We sought to determine whether maternal carbohydrate quantity and quality are associated with newborn aortic intima-medial thickness in healthy pregnancies. Maternal diet throughout pregnancy was evaluated in 139 mother–child dyads using a validated food frequency questionnaire. Carbohydrate intake was expressed as quantity (% total energy), quality (fibre, glycaemic index), and glycaemic burden (glycaemic load). Aortic intima-medial thickness was measured by high-frequency ultrasound of the neonatal abdominal aorta. Neither quantity nor quality of maternal carbohydrate intake during pregnancy was associated with meaningful differences in offspring maximum aortic intima-medial thickness with the exception of fibre intake in women with overweight or obesity which was inversely associated (−8 μm [95% CI −14, −1] per g fibre, p = 0.04). In healthy pregnancy, the quantity and quality of maternal carbohydrate intake is likely not a meaningful modifiable lifestyle factor for influencing offspring vascular health. The effect of carbohydrate quality may only be evident in high-risk pregnancies, consistent with previous findings. These findings may be confirmed in prospective dietary trials in pregnancy.
5
Abd Rahim, Ismail, et Mohamad Saiful Nizam Mohamad. « TUNNEL SUPPORT BY ROCK QUALITY INDEX (Q) SYSTEM FOR ULTRABASIC ROCK : A CASE STUDY IN TELUPID, SABAH, MALAYSIA ». Malaysian Journal of Geosciences 4, no 1 (28 février 2020) : 22–25. http://dx.doi.org/10.26480/mjg.01.2020.22.25.
Texte intégralRésumé :
The study area is underlain by the ultrabasic rock of partly Sabah Ophiolite Complex of Cretaceous ages. The objectives of this study are to determine the Q-value and to estimate the permanent support measures for 20m span, 10m high and eastern direction of the proposed tunnel in the study area. Engineering geological mapping (lithological and surface mapping and discontinuity survey), laboratory study (petrographical study) and testing (Uniaxial Compressive Strength testing) and data analysis (stereographic plots, Q system parameters evaluation and support estimation) was used in this study. The results show that the rock mass is classified as lherzolite, strong, excellent quality, more than four joint sets, slightly altered discontinuity wall, dry excavation and favourable stress condition. The equivalence dimension (De) are 15.4 for the permanent roof. The Q-value for permanent roof and wall of the proposed tunnel are 1.4 (Class D or poor and type 5) and 3.5 (Class D or poor and type 3), respectively. The permanent and temporary supports for the roof and wall are systematic bolting, 700J energy absorption of fiber reinforce sprayed concrete, 9-12 and 5- 6 cm thick fiber reinforce shotcrete, respectively.
6
Huang, Changfu, Shuguang Tian, Qun Li et Jun Huang. « Evaluation of Rock Quality of Tunnel Wall Rock Based on Rough Set Theory and Unascertained Measurement Theory ». Mathematical Problems in Engineering 2018 (24 juillet 2018) : 1–10. http://dx.doi.org/10.1155/2018/3571028.
Texte intégralRésumé :
A method for classification of the tunnel wall rock is established based on the rough set theory and unascertained measurement theory. The saturated uniaxial compressive strength, rock mass integrity index, structural surface condition, seepage measurement of groundwater, and the angle between the hole axis and main structural surface are selected as the evaluation indexes. The problem of weight coefficients for these evaluation indexes is converted into that of significance estimating on the attributes in the rough set theory. The proposed method is verified by the wall rock data of Yuanyanghui tunnel. The results show that the proposed method has an excellent performance in good agreement with the practical situation of wall rock and is feasible to classify the wall rock. Finally, the proposed method is applied to Xihualing tunnel of Zhu-Yong Expressway. The results are basically the same as those from Delphi-ideal point method, set pair analysis method, and the actual situation, which proves that the rough set theory and unascertained measurement theory are effective for classification of the wall rock.
7
Pujol, Santiago, Lucas Laughery, Aishwarya Puranam, Pedram Hesam, Li-Hui Cheng, Alana Lund et Ayhan Irfanoglu. « Evaluation of Seismic Vulnerability Indices for Low-Rise Reinforced Concrete Buildings Including Data from the 6 February 2016 Taiwan Earthquake ». Journal of Disaster Research 15, no 1 (1 février 2020) : 9–19. http://dx.doi.org/10.20965/jdr.2020.p0009.
Texte intégralRésumé :
Communities need seismic vulnerability indices to identify which buildings are most susceptible to severe damage during earthquakes. To be of greatest value, these indices should be easy to use and should be vetted against data from previous earthquakes. To date, more than 800 reinforced concrete buildings have been surveyed after earthquakes for the purpose of evaluating a seismic vulnerability index proposed by Hassan and Sozen in 1997. This number includes 130 buildings surveyed after the 6 February 2016 earthquake in Taiwan. The data collected during these surveys consist of descriptions and photographs of damage, structural sketches, and measurements. Analyses of the data indicate that probability of severe damage and failure increases with decreasing column index and wall index (normalized measures of column and wall areas). They also suggest that the exact form of the threshold used to distinguish more vulnerable structures from less vulnerable structures is of little consequence in terms of the probable cost and benefits of the strengthening program this threshold may inform.
8
Soudah, Eduardo, E. Y. K. Ng, T. H. Loong, Maurizio Bordone, Uei Pua et Sriram Narayanan. « CFD Modelling of Abdominal Aortic Aneurysm on Hemodynamic Loads Using a Realistic Geometry with CT ». Computational and Mathematical Methods in Medicine 2013 (2013) : 1–9. http://dx.doi.org/10.1155/2013/472564.
Texte intégralRésumé :
The objective of this study is to find a correlation between the abdominal aortic aneurysm (AAA) geometric parameters, wall stress shear (WSS), abdominal flow patterns, intraluminal thrombus (ILT), and AAA arterial wall rupture using computational fluid dynamics (CFD). Real AAA 3D models were created by three-dimensional (3D) reconstruction of in vivo acquired computed tomography (CT) images from 5 patients. Based on 3D AAA models, high quality volume meshes were created using an optimal tetrahedral aspect ratio for the whole domain. In order to quantify the WSS and the recirculation inside the AAA, a 3D CFD using finite elements analysis was used. The CFD computation was performed assuming that the arterial wall is rigid and the blood is considered a homogeneous Newtonian fluid with a density of 1050 kg/m3and a kinematic viscosity of4×10-3Pa·s. Parallelization procedures were used in order to increase the performance of the CFD calculations. A relation between AAA geometric parameters (asymmetry index (β), saccular index (γ), deformation diameter ratio (χ), and tortuosity index (ε)) and hemodynamic loads was observed, and it could be used as a potential predictor of AAA arterial wall rupture and potential ILT formation.
9
Liang, Ze, Zisheng Luo, Wenxuan Li, Mingyi Yang, Lei Wang, Xingyu Lin et Li Li. « Elevated CO2 Enhanced the Antioxidant Activity and Downregulated Cell Wall Metabolism of Wolfberry (Lycium barbarum L.) ». Antioxidants 11, no 1 (22 décembre 2021) : 16. http://dx.doi.org/10.3390/antiox11010016.
Texte intégralRésumé :
Modified atmosphere packaging (MAP) has been widely known to delay the postharvest fruit senescence; nevertheless, its effect on antioxidant activity and cell wall metabolism of wolfberry fruit is largely unknown. The present study investigated the impact of elevated CO2 on the quality attributes and cell wall degradation of wolfberry fruit during storage. The results showed that 10% CO2 better maintained the physiological quality and conferred the reduction in weight loss, decay index, and color change. Higher 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-1-picrylhydrazil (DPPH) radical scavenging activity, total phenol and flavonoid content, and superoxide dismutase (SOD) and catalase (CAT) activity of wolfberry were detected at elevated CO2 concentrations. Elevated CO2 atmosphere contributed to the maintenance of the cell integrity, the decrease of cell wall degradation (polygalacturonase, pectate lyase, cellulase, and β-glucosidase), and the increase of cellulose and proto pectin content. Overall, we revealed the potential mechanism of elevated CO2 on the antioxidant activity enhancement and cell wall homeostasis of fresh berry fruit.
10
Wang, Jian Gang, Hua Lin Wang, Yi Fan et Yuan Huang. « The Index Matching Method and its Application in V3V Measurements ». Advanced Materials Research 1051 (octobre 2014) : 946–50. http://dx.doi.org/10.4028/www.scientific.net/amr.1051.946.
Texte intégralRésumé :
In imaging measurements on the fluid flow, the quality of particle image is essential to the outcomes of the velocity field. The method to eliminate the problems of refraction and reflection is to match the refractive indices of the working fluid and the surrounding solid wall. In this article, a comprehensive summary of the refractive index matching method was presented. Three fluid materials, two organic and one non-organic was used to conduct index matching and their effect were compared. Results show the perfect index matching is effective to improve the measurement accuracy of imaging measurements.
Thèses sur le sujet "Wall Quality Index"
1
Stefanini, Sara. « Il Patrimonio architettonico delle culture del Maghreb a rischio di scomparsa per perdita di conoscenza ed aggressione ambientale. Valutazione delle vulnerabilità e del rischio sismico della medina di Fes in Marocco ». Doctoral thesis, 2020. http://hdl.handle.net/2158/1190289.
Texte intégralRésumé :
The research project intends to develop a methodology for the conservation of the architectural heritage in the Maghreb countries, threatened by both natural (in particular seismic events) and anthropic attacks (loss of knowledge and uncritical affirmation of technological cultures incompatible with the previous ones). The field of application of the study was the Medina of Fes in Morocco, considered a representative example of the processes and dynamics in progress. The theme of preservation of cultural heritage is investigated following a multidisciplinary approach in which the purely technical aspects have been addressed by seeking comparison with socio-cultural aspects.
In order to gain an in-depth knowledge of the systems and construction types characterizing the area under investigation, it was decided to study the living and construction culture in northern Morocco and specifically in the Fes region, paying attention, thanks to field investigations, on the main critical points of the buildings and on the techniques that can be associated with the “rule of the art”, including those devices that seem to play a role in contrasting the seismic action. In addition, for the same purpose, a survey campaign was carried out on traditional masonry as representative of recurrent types, trying to associate a structural assessment with it and verify its mechanical properties. In particular, the following were carried out: a) physical-mineralogical analyses on mortar and brick samples; b) mechanical characterization tests, i.e. compression tests, indirect traction tests and three-points-bending tests for on brick samples; c) an evaluation of the efficiency of the different wall types through the application of the Wall Quality Index (IQM) integrating it into the GNDT data form; d) tilt tests on wall models to assess the contribution to the resistance in the plane of the walls by the wooden “radications”, characteristic of the local construction technique.
The results obtained allowed to support the subsequent analysis phase
related to the evaluation of seismic vulnerability, a subject that has not yet been sufficiently studied in the Maghreb area. A methodology is then proposed for assessing the seismic vulnerability calibrated on the specific characteristics of historical settlements (essentially consisting of patio buildings in aggregate) that can be extended and replicated in other similar contexts. The proposed method is based on the II level GNDT Vulnerability Index and allowed the realization of vulnerability curves, fragility curves, damage scenarios for different seismic intensities and loss scenarios. The results of the vulnerability assessment are also presented through their spatial distribution in the form of maps created in the GIS environment.
Finally, the proposed methodology for the assessment of seismic vulnerability was applied a second time to the case study imagining that it had performed a consolidation of the building through the implementation of interventions for coherent and mechanically compatible with the historicized building structural reinforcement.
Chapitres de livres sur le sujet "Wall Quality Index"
1
Drechsler, Andreas, Steffi Reinhold, Andreas Ruff, Martin Schneider et Berndt Zeitler. « Airborne Sound Insulation of Sustainable Building Facades ». Dans iCity. Transformative Research for the Livable, Intelligent, and Sustainable City, 335–57. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92096-8_22.
Texte intégralRésumé :
AbstractTwo trends are currently leading to an increased risk of indoor noise pollution. Firstly, urban densification causes traffic noise sources to be closer to the building facades which makes them louder at the facades. Secondly, airtightness of buildings, due to energy regulations, leads to the need of natural or mechanical ventilation to ensure a “healthy” indoor air quality, thereby allowing noise to easily pass from outdoors to indoors. In the case of mechanical ventilation, an additional noise source is also created. This study investigates the risk reduction of an indoor noise problem by optimizing the facade elements regarding sound insulation. Noise levels of different transportation noise sources (cars, trucks, trains) are used to calculate the resulting indoor noise levels after passing through the facade elements. The amount of noise transmitted into the indoors is dependent on the frequency spectra of the sources and of the sound reduction properties of the facade elements. Facade elements such as masonry walls, open windows, and ventilators are investigated and modified regarding their sound insulation properties. Through passive means, the weighted sound reduction index of an open window and an open ventilator was increased by 12 dB and 3 dB, respectively. Also, the indoor self-noise of the ventilator was investigated and reduced for different airflow rates.
2
Steiner, Erich. « Elterliche Kontroll- und Wertregulationen und die Lernmotivation des Kindes ». Dans Schulbezogene Motivierungspraktiken von Eltern, 171–272. Wiesbaden : Springer Fachmedien Wiesbaden, 2021. http://dx.doi.org/10.1007/978-3-658-33062-0_5.
Texte intégralRésumé :
ZusammenfassungDas vorliegende Kapitel nimmt das elterliche schulbezogene verbale Motiverungshandeln in den Blick. Dazu werden zuerst die intramentalen Prozesse beim Kind beleuchtet, welche die Eltern zu beeinflussen versuchen: Erwartungswert-theoretischen Konzeptionen der Leistungsmotivation und -emotion (Pekrun & Perry, 2014; Wigfield, Eccles, et al., 2015) zufolge sind es namentlich die Kontroll- und Wertüberzeugungen des Kindes, die darüber entscheiden, welchen schulischen Aktivitäten und Zielen es sich zuwendet sowie mit welcher Qualität und welchem Erfolg es sich diesen widmet. Kontrollüberzeugungen, generalisierte subjektive Vorstellungen davon, inwieweit man in bestimmten Domänen sein Handeln und die Handlungsergebnisse selbst beeinflussen kann (vgl. Preiser & Sann, 2010, S. 387), bestimmen die situative Erfolgszuversicht beim Planen und Durchführen eigener Lernhandlungen und werden ihrerseits durch Erfolgs- und Misserfolgserfahrungen und deren subjektive Deutungen – sogenannte Kausalattribuierungen (vgl. Abschnitt 5.3.3.1) – geprägt. Eltern können vor, während und nach Lern- und Leistungssituation mittels Feedbacks auf die Kontrollkognitionen des Kindes Einfluss nehmen, indem sie es auf gelingende und misslingende Aspekte seines Tuns hinweisen und dafür mehr oder weniger explizit Gründe geltend machen. Wertüberzeugungen – individuelle Präferenzen für bestimmte Verhaltensklassen, Konzepte und Ziele – bestimmen dahingegen, welche subjektive Bedeutung man einer bestimmten Aufgabe zumisst. In Abschnitt 5.5 wird die Theorie des Subjective Task Value von Eccles, Wigfield und Kolleg*innen (Eccles, 2005; Wigfield & Eccles, 1992) erörtert, welche vier Beweggründe für die Wahl einer Aktivität postuliert. In ähnlicher Art wie bei den evaluativen Feedbacks können Eltern vor, während und nach Lern- und Leistungssituationen versuchen, auf die task values des Kindes Einfluss zu nehmen, indem sie vor diesem ihre eigenen aktivitätsbezogenen Bedeutsamkeitszuschreibungen verbalisieren. Der letzte Teil des Kapitels widmet sich nochmals detaillierter der Frage, welche kommunikativen Bedingungen verbale Kontroll- und Wertregulationen erfüllen sollten, damit die von den Eltern intendierte Botschaft mit hoher Wahrscheinlichkeit vom Kind aufgenommen und internalisiert wird.
3
Asim, Muhammad. « Early symptoms and pointers to early diagnosis ». Dans Ankylosing Spondylitis and Axial Spondyloarthritis, 36—C5.P23. 2e éd. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780198864158.003.0005.
Texte intégralRésumé :
Abstract Back pain is very prevalent in the general population but AS/axSpA is not its commonest cause. In the beginning, AS usually causes pain and stiffness felt in the buttock area and lower back due to inflammation of the sacroiliac joints and lower spine in a teenager or a young adult. This inflammatory back pain is worsened on prolonged rest and eased on physical exercise or intake of non-steroidal anti-inflammatory drugs (NSAIDs). Most patients first seek medical help when their back pain and stiffness become persistent and troublesome; and it may become a major impediment to good sleep. A few patients may present with pain in the hip (groin) or knee joint, or tenderness of some bones, such as the chest wall or the heels. Others may present with an acute inflammation of the eye, psoriasis, inflammatory bowel disease, pain in the limb joints, or tenderness of some bones, such as the chest wall or the heels. Unless the physician has ample clinical experience and a high index of suspicion, many cases will be missed. An early diagnosis and a proper medical management are crucial as it can help alleviate symptoms, reduce the risk of long-term disability and deformity, and enhance quality of life.
Actes de conférences sur le sujet "Wall Quality Index"
1
Campos, Rafael, Lisandro Lovisolo et Marcello Campos. « Evaluation of RF Through-The-Wall Mapping Reconstruction Methods using an Objective Image Quality Index ». Dans XXXVII Simpósio Brasileiro de Telecomunicações e Processamento de Sinais. Sociedade Brasileira de Telecomunicações, 2019. http://dx.doi.org/10.14209/sbrt.2019.1570556182.
Texte intégral
2
Hong, Jiarong, Joseph Katz et Michael Schultz. « Near-Wall Stereo PIV Investigation of the Turbulent Channel Flow Over Rough-Walls ». Dans ASME 2008 Fluids Engineering Division Summer Meeting collocated with the Heat Transfer, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/fedsm2008-55197.
Texte intégralRésumé :
The near-wall turbulent flow in the rough-wall channel is of great significance in engineering applications, but remains a challenge for both experimental measurement and numerical modeling due to the complexity of the roughness geometry. For optical measurement techniques, e.g. PIV, obstruction by the roughness elements and reflection from the surface adversely affect the quality of near wall data. Our present study utilizes a facility containing a fluid with the same refractive index as the rough acrylic wall, making the interface almost invisible, and employs Stereo PIV to obtain the three-dimensional flow field in the vicinity of the roughness elements. The roughness shape is a uniformly distributed and closely packed, 0.5 mm high pyramid, corresponding to 95 wall units, with a pitch angle of 22.5 degrees. The length of the rough surface is sufficiently long to obtain self-similar roughness boundary layer, turbulent channel flow at a mean velocity of 3.8 m/s, with a clearly defined log layer. Results will include sample data of the complete flow, both around and above the roughness elements. Issues related to implementation of Stereo PIV in an index-matched facility will be discussed.
3
Van-Le, Thuy Hong, Sangmo Kang, Yong Kweon Suh et Yangyang Wang. « Chaotic Mixing in Three-Dimensional Micro Channel ». Dans ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer. ASMEDC, 2008. http://dx.doi.org/10.1115/mnht2008-52193.
Texte intégralRésumé :
The quality of chaotic mixing in three-dimensional micro channel flow has been numerically studied using Fractional-step method (FSM) and particle tracking techniques such as Poincare´ section and Lyapunov exponents. The flow was driven by pressure distribution and the chaotic mixing was generated by applying alternating current to electrodes embedded on the bottom wall at a first half period and on the top wall at a second half period. The equations governing the velocity and concentration distributions were solved using FSM based on Finite Volume approach. Results showed that the mixing quality depended significantly on the modulation period. The modulation period for the best mixing performance was determined based on the mixing index for various initial conditions of concentration distribution. The optimal values of modulation period obtained by the particle tracking techniques were compared with those from the solution of concentration distribution equation using FSM and CFX software and the comparison showed their good match.
4
Saghafi, Fariborz, et Afshin Banazadeh. « Coanda Surface Geometry Optimization for Multi-Directional Co-Flow Fluidic Thrust Vectoring ». Dans ASME Turbo Expo 2009 : Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59715.
Texte intégralRésumé :
The performance of Co-flow fluidic thrust vectoring is a function of secondary flow characteristics and the fluidic nozzle geometry. In terms of nozzle geometry, wall shape and the secondary slot aspect ratio are the main parameters that control the vector angle. The present study aims to find a high quality wall shape to achieve the best thrust vectoring performance, which is characterized by the maximum thrust deflection angle with respect to the injected secondary air. A 3D computational fluid dynamics (CFD) model is employed to investigate the flow characteristics in thrust vectoring system. This model is validated using experimental data collected from the deflection of exhaust gases of a small jet-engine integrated with a multi-directional fluidic nozzle. The nozzle geometry is defined by the collar radius and its cutoff angle. In order to find the best value of these two parameters, Quasi-Newton optimization method is utilized for a constant relative jet momentum rate, a constant secondary slot height and insignificant step size. In this method, the performance index is described as a function of thrust deflection angle. Optimization parameters (wall geometric parameters) are estimated in the direction of gradient, with an appropriate step length, in every iteration process. A good guess of initial optimization parameters could lead to a rapid convergence towards an optimal geometry and hence maximum thrust deflection angle. Examination over a range of geometric parameters around the optimum point reveals that this method promises the best performance of the system and has potential to be employed for all the other affective factors.
5
Haynes, Mark D., Chih-Hang John Wu, Matthew Arnold, Naga Narendra B. Bodapati, B. Terry Beck et Robert J. Peterman. « Bond Index Numbers of Prestressed Concrete Reinforcement Wires and Their Relationships to Transfer Lengths and Pull-Out Forces ». Dans 2016 Joint Rail Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/jrc2016-5787.
Texte intégralRésumé :
The purpose of this research is to establish mathematical models that predicts the bond strength of a reinforcement wire in prestressed concrete members, given the known geometrical features of the wire. A total of nineteen geometrical features of the reinforcement wire were measured and extracted by a precision non-contact profilometer. With these mathematical models, prestressing reinforcement wires can now be analyzed for their bond strength without destructive testing. These mathematical models, based upon a large collection of empirical data via prestressing reinforcement wires from various wire manufacturers in US and Europe, have the potential to serve as quality assessment tools in reinforcement wire and prestressed concrete member production. Most of these models are very simple and easy to implement in practice, which could provide insight into which reinforcement wires provide the greatest bond strength and which combinations of geometrical features of the reinforcement wire are responsible for providing the bond strength. Our various empirical models have shown that the indent side-wall angle, which is suggested by the ASTM-A881/A881M, may not be the only significant geometrical feature correlated to the transfer length and bond strengths. On the contrary, features such as the indent surface area, indent width, indent edge surface area, indent volume, and release strengths do have significant correlations with the ultimate transfer lengths of the prestressed concrete members. Extensive experiments and testing performed at the Structures Laboratory in Kansas State University, as well as field tests at Transportation Technology Center, Inc. (TTCI) and one Prestressed Concrete Railroad Tie manufacturing facility, have been used to confirm the model predictions. In addition, our experimental results suggest that the maximum pull out force in the un-tensioned pullout testing has significant correlation with the ultimate transfer length. This finding could provide reinforcement wire manufactures with a quality assurance tool for testing their wires prior to the production. The resultant mathematical model relating the wire geometrical features to transfer length is referred to as the Bond Index Number (BIN). The BIN is shown to provide a numerical measure of the bond strength of prestressing steel reinforcement wire, without the need for performing destructive tests with the reinforcement wire. We believe that with the BIN and the maximal pull-out forces from the un-tensioned pull-out tests, one can have better insight into the optimal reinforcement wire design by testing the performance of wires before they are put into production lines.
6
Krenitsky, Helene A., Evan T. Hurlburt, Larry B. Fore, Paul T. McKeown et Richard B. Williams. « Flow Visualization in Boiling Water Flows Leading Up to Departure From Nucleate Boiling in an Electrically-Heated Duct ». Dans ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/ht2009-88515.
Texte intégralRésumé :
A fundamental departure from nucleate boiling (DNB) flow visualization experiment was designed to obtain a better understanding of flow boiling by visually capturing the mechanisms leading up to and including DNB for subcooled vertical flow boiling. At the critical heat flux (CHF) the heat transfer coefficient between the wall and fluid is greatly reduced, entering an inefficient heat transfer region that can cause a rapid increase in wall temperature. Most of the visual data on DNB in the open literature comes from experiments conducted with refrigerants or with water at relatively low pressure. One goal of this test was to capture high-quality photographs leading up to DNB for water at higher pressures, higher mass fluxes, and larger inlet subcooling than most of the data in the open literature. The fundamental DNB experiment consisted of three different run stages: incipient boiling, subcooled boiling, and CHF runs, which were intended to capture the behavior leading up to and including a departure from nucleate boiling crisis. At high heat flux conditions, the steep temperature and refractive-index gradients in the water near the wall act like lenses and bend the light away from the wall, which is the region of interest for discerning the DNB mechanism. By frosting the inner surface of the window on the light source side, the nearly collimated light was diffused as it entered the test section and enabled better visualization near the wall region. A high speed camera was used in testing. A typical run consisted of a 2 second image data set, with a resolution of 512 by 160 pixels, at 10,000 frames per second. Three excursive CHF runs were achieved, the last of which melted the test section. The trigger function on the camera captured images from before and after the power trip for the last CHF run. A trend can be seen of an increasing two-phase friction factor with power that begins to increase more rapidly at test section powers greater than 64.5kW. The 1995 Groenevel, et al. (1996) look-up table proved to be a good estimate of the heat flux at DNB.
7
McIlroy, Hugh M., Donald M. McEligot et Robert J. Pink. « Idaho National Laboratory Experimental Program to Measure the Flow Phenomena in a Scaled Model of a Prismatic Gas-Cooled Reactor Lower Plenum for Validation of CFD Codes ». Dans Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58043.
Texte intégralRésumé :
The experimental program that is being conducted at the Matched Index-of-Refraction (MIR) Flow Facility at Idaho National Laboratory (INL) to obtain benchmark data on measurements of flow phenomena in a scaled model of a prismatic gas-cooled reactor lower plenum using 3-D Particle Image Velocimetry (PIV) is presented. A description of the scaling analysis, experimental facility, 3-D PIV system, measurement uncertainties and analysis, experimental procedures and samples of the data sets that have been obtained are included. Samples of the data set that will be presented include the mean velocity field in an approximately 1:7 scale model of a region of the lower plenum of a typical prismatic gas-cooled reactor (GCR) similar to a General Atomics Gas-Turbine-Modular Helium Reactor (GTMHR) design. This experiment has been selected as the first Standard Problem endorsed by the Generation IV International Forum. The flow in the lower plenum consists of multiple jets injected into a confined cross flow — with obstructions. The model consists of a row of full circular posts along its centerline with half-posts on the two parallel walls to approximate flow scaled to that expected from the staggered parallel rows of posts in the reactor design. The model is fabricated from clear, fused quartz to match the refractive-index of the mineral oil working fluid. The benefit of the MIR technique is that it permits high-quality measurements to be obtained without locating intrusive transducers that disturb the flow field and without distortion of the optical paths. An advantage of the INL MIR system is its large size which allows obtaining improved spatial and temporal resolution compared to similar facilities at smaller scales. Results concentrate on the region of the lower plenum near its far reflector wall (away from the outlet duct). Inlet jet Reynolds numbers (based on the jet diameter and the time-mean average flow rate) are approximately 4,300 and 12,400. The measurements reveal developing, non-uniform flow in the inlet jets and complicated flow patterns in the model lower plenum. Data include three-dimensional vector plots, data displays along the coordinate planes (slices) and charts that describe the component flows at specific regions in the model. Information on inlet velocity profiles is also presented.
8
Stadie-Frohbös, Gundula, et Jörg Lampe. « Risk Based Inspection for Aged Offshore Pipelines ». Dans ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11119.
Texte intégralRésumé :
Today risk based inspection (RBI) has become very popular as it allows the inspection budget to be used more efficiently compared to conventional inspection procedures. The key parts of a risk based inspection programme for aged pipelines is the determination of all relevant risk driving effects for each specific pipeline, the definition of acceptance criteria and the assessment of the residual lifetime for the pipeline. These tasks require a high level of co-operation with the pipeline operator and the RBI-experts. This paper describes some of the major aspects of the methodology developed to estimate the risk to offshore pipelines. Based on the assessment of the risk an optimised inspection strategy can be developed. The complete RBI-process typically starts by gathering all relevant data used in design phase (including construction phase) and operation phase. In most cases a variety of risk assessment methods will be used, depending on the quality of existing pipeline data. When insufficient data is available a simple qualitative assessment with an index procedure can be used. With more detailed data available the method becomes a semi-quantitative approach. This paper presents the results of a general risk assessment of 22 aged offshore pipelines. Although only basic data has been available this was sufficient to work out reliable results within a semi-quantitative approach. Depending on varying wall thickness, diameter, etc. a pipeline was divided into several different segments. The assessment reveals different governing threats and failure modes for pipelines and risers, like ageing, free span or corrosion. In a final step the results of the risk assessment are used for the optimisation of the inspection intervals within the proposed risk based inspection framework.