Academic literature on the topic 'Three-hole Probes'
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Journal articles on the topic "Three-hole Probes"
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Sitaram, N., and A. L. Treaster. "A Simplified Method of Using Four-Hole Probes to Measure Three-Dimensional Flow Fields." Journal of Fluids Engineering 107, no. 1 (March 1, 1985): 31–35. http://dx.doi.org/10.1115/1.3242436.
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A simplified method of using four-hole probes to measure three-dimensional flow-fields is presented. This method is similar to an existing calibration and application procedure used for five-hole probes. The new method is demonstrated for two four-hole probes of different geometry. These four-hole probes and a five-hole probe are used to measure the turbulent boundary layer on a flat plate. The results from the three probes are in good agreement with theoretical predictions. The major discrepancies occur near the surface of the flat plate and are attributed to wall vicinity and velocity gradient effects.
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Cull, James, and Duncan Massie. "Noise Reduction for Down-hole Three-component TEM probes." ASEG Extended Abstracts 2001, no. 1 (December 2001): 1–3. http://dx.doi.org/10.1071/aseg2001ab027.
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Sitaram, Nekkanti, and Kancherla Srikanth. "Effect of Chamfer Angle on the Calibration Curves of Five Hole Probes." International Journal of Rotating Machinery 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/704315.
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Five hole probes are extensively used for measurement of total and static pressures, flow angles, velocity and its components in turbomachinery, and other aerodynamic flows. Their operating range is usually limited to 30–40° depending on the type of the probe head. The chamfer angle of the probe is usually taken around 45°. Recent studies on three hole probes have shown that 30° chamfer angle is desirable for unsteady flow measurements. Hence the present investigation is undertaken to find the optimum chamfer angle of five-hole probes. A special five-hole probe of 9.6 mm head diameter and 3 mm diameter pressure take off tubes was designed and fabricated. The large size of the probe was chosen to minimize machining inaccuracies. The probe chamfer angle was varied from 30° to 60° in 5° steps. For each of the chamfer angles, the probe was calibrated in the range of −30° to +30° in 5° interval and the calibration curves are presented. In addition the sensitivities of the calibration coefficients are determined. It is concluded that five-hole probe with a chamfer angle 30° has large operating range, while five-hole probe with a chamfer angle of 50° has good sensitivity.
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Argüelles Díaz, K. M., J. M. Fernández Oro, E. Blanco Marigorta, and R. Barrio Perotti. "Head geometry effects on pneumatic three-hole pressure probes for wide angular range." Flow Measurement and Instrumentation 21, no. 3 (September 2010): 330–39. http://dx.doi.org/10.1016/j.flowmeasinst.2010.04.004.
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Khalil, M. B., and E. G. Plett. "Measurement of Temperature and Velocity Vectors in a Combusting Environment Using Low-Cost Probes." Journal of Engineering for Gas Turbines and Power 110, no. 4 (October 1, 1988): 695–703. http://dx.doi.org/10.1115/1.3240194.
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Radial traverses were made to measure temperature distributions and velocity vectors in an atmospheric pressure test combustor burning gaseous fuels with heating values in the low-medium range. Temperature was measured using an aspirated pyrometer probe. Velocity vectors were determined from measurements of a five-hole probe (a two-hole probe was used prior to the five-hole probe to determine whether the flow was directed upstream or downstream). The measuring traverse was carried out across the entire diameter at ten sections along the combustor (which was specially designed to allow in insertion of probes at the ten axial sections, through three holes at 120 deg from each other around the circumference). These measurements were repeated for ten runs that incorporated a variety of operating conditions of the combustor. Temperature measurements were validated by application of the first law of thermodynamics. Velocities were validated using the principles of conservation of mass and angular momentum. The analysis showed that temperatures can be measured to within 10°C in a combusting environment of gaseous fuels for which the temperature is in the vicinity of 1500 K, by an aspirated pyrometer. The axial velocity component can be measured to an average accuracy of 7.6 percent using five-hole probes. The radial component of velocity can be obtained within ± 5 percent in most of the combustion space. The accuracy of measuring the circumferential velocity component could not be validated, partly because it was extremely small. Also, in order to validate it, some independent means of establishing its origin is needed. In this case, due to the lack of precision in fabricating the combustor and the holes for air admission, as well as due to the extremely small value of this component in the present study, it was not possible to establish the reliability of the measured values. The study recommends the use of aspirated pyrometers and five-hole probes in a combusting environment, provided that the yaw angle does not exceed 60 deg and the three components of velocity have comparable magnitudes. The probes should be made as small as possible and frequent purging should be practiced in their operation to avoid errors due to blockage of probes’ passages by water or dust particles. These probes were chosen for this application because of the ease with which they can be used, as well as for cost considerations.
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Dominy, R. G., and H. P. Hodson. "An Investigation of Factors Influencing the Calibration of Five-Hole Probes for Three-Dimensional Flow Measurements." Journal of Turbomachinery 115, no. 3 (July 1, 1993): 513–19. http://dx.doi.org/10.1115/1.2929281.
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The effects of Reynolds number, Mach number, and turbulence on the calibrations of commonly used types of five-hole probe are discussed. The majority of the probes were calibrated at the exit from a transonic nozzle over a range of Reynolds numbers (7 × 103 < Re < 80 × 103 based on probe tip diameter) at subsonic and transonic Mach numbers. Additional information relating to the flow structure were obtained from a large-scale, low-speed wind tunnel. The results confirmed the existence of two distinct Reynolds number effects. Flow separation around the probe head affects the calibrations at relatively low Reynolds numbers while changes in the detailed structure of the flow around the sensing holes affects the calibrations even when the probe is nulled. Compressibility is shown to have little influence upon the general behavior of these probes in terms of Reynolds number sensitivity but turbulence can affect the reliability of probe calibrations at typical test Reynolds numbers.
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Yao, Tao, Shudao Zhou, and Song Ye. "Design and Test of an Integrated Measurement System for Multi-Hole Probe Calibration and Vortex Measurement." Sensors 22, no. 6 (March 19, 2022): 2376. http://dx.doi.org/10.3390/s22062376.
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Multi-hole probes can simultaneously measure the velocity and direction of a flow field, obtain the distribution of the flow field in a three-dimensional space, and obtain the vortex information in the flow field. Moreover, a multi-hole probe needs to be calibrated while in use; therefore, a three-coordinate, multi-directional rotatable testing system, which can measure the flow field at any position and at any angle, was designed herein. A hemispherical seven-hole probe was calibrated with this test system, and the flow field around cylinders of different diameters was measured to obtain the pressure distribution and vortex shedding frequency. Furthermore, the designed test system’s ability to perform a multi-angle and multi-azimuth testing during the calibration of a multi-hole probe was verified. Simultaneously, through data mining of the multi-hole probe, vortices were measured, and periodic vortices were detected.
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Harrison, S. "Secondary Loss Generation in a Linear Cascade of High-Turning Turbine Blades." Journal of Turbomachinery 112, no. 4 (October 1, 1990): 618–24. http://dx.doi.org/10.1115/1.2927702.
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Flow through a linear cascade of high-turning, low aspect ratio turbine blades has been measured in great detail at five planes within the cascade and two downstream in order to trace the generation of stagnation pressure loss in the passage. Five-hole probes were used in the main flow, but as it is important to resolve the boundary layers accurately, three-hole and single flattened probes were used near the endwall and blade surfaces, respectively. Endwall shear stresses have been measured using a hot-film probe and an oil-drop viscosity balance technique. Numerical predictions and simple aerodynamic models are used in conjunction with the experimental data to estimate the relative importance of different loss mechanisms, including boundary layer shear stresses and mixing processes.
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Harada, H. "Performance Characteristics of Two- and Three-Dimensional Impellers in Centrifugal Compressors." Journal of Turbomachinery 110, no. 1 (January 1, 1988): 110–14. http://dx.doi.org/10.1115/1.3262155.
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The overall performance of two- and three-dimensional impellers of a centrifugal compressor were tested and compared. A closed-loop test stand with Freon gas as the working fluid was employed for the experiments. The inlet and outlet velocity distributions of all impellers were measured using three-hole cobra probes. As a result, it has been revealed that three-dimensional impeller in terms of efficiency, head coefficient, and operating range. Further, it has also been clarified that the impeller slip factor is affected by blade angle distribution.
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Coldrick, Simon, Paul Ivey, and Roger Wells. "Considerations for Using 3-D Pneumatic Probes in High-Speed Axial Compressors." Journal of Turbomachinery 125, no. 1 (January 1, 2003): 149–54. http://dx.doi.org/10.1115/1.1515334.
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This paper describes preparatory work towards three-dimensional flowfield measurements downstream of the rotor in an industrial, multistage, axial compressor, using a pneumatic pressure probe. The probe is of the steady-state four-hole cobra probe type. The design manufacture and calibration of the probe is described. CFD calculations have been undertaken in order to assess the feasibility of using such a probe in the high-speed compressor environment where space is limited. This includes effects of mounting the probe in close proximity to the downstream stator blades and whether it is necessary to adjust the calibration data to compensate for these effects.
Dissertations / Theses on the topic "Three-hole Probes"
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O'Dowd, Devin Owen. "Aero-thermal performance of transonic high-pressure turbine blade tips." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:e7b8e7d0-4973-4757-b4df-415723e7562f.
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Ferreira, Tânia Sofia Cação. "Calibration and data processing of fast-response virtual three-hole probes." Master's thesis, 2015. http://hdl.handle.net/10400.6/5390.
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Fast response pressure probes are a robust measurement technique to characterize time-resolved unsteady flow in turbomachinery. An extensive data-processing is necessary to fabricate the appropriate and crucial calibration data for the intended flow quantities range.
Final aerodynamic calibration is available due to post processing of static and angular calibration data of nine fast response probes with two different transducer devices.
Finally, an uncertainty analysis of pressure and sensor angle errors as well as pitch angle effect is made recurring to pressure values from angular calibration data.A caraterização contínua no tempo do escoamento transiente presente no interior de turbomáquinas pode ser realizado por sondas de resposta rápida. Estes instrumentos permitem a implementação de uma técnica de medição robusta da pressão total e estática em função do tempo, assim como da direção do escoamento, se um número suficiente de sensores for utilizado. Para o efeito, é necessário um extenso processamento de dados para gerar informação de calibração apropriados e cruciais para o intervalo de alcance das propriedades do escoamento desejadas. A calibração aerodinâmica final é obtida após o processamento da calibração estática e dinâmica de nove sondas de pressão de resposta rápida com dois tipos diferentes de sensores. Por fim, uma análise de incertezas quanto a erros de pressão e de posicionamento angular do sensor da sonda assim como o efeito do ângulo de arfagem é realizada recorrendo a valores de pressão dos dados de calibração angular.
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Chen, Y. S., and 陳盈憲. "Calibration of three-hole pressure probe and its application in swirl flow measurement." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/09651027352426371155.
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碩士國立成功大學
航空太空工程學系
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Using a tree-tube pressure probe for mean streamwise velocity and flow angle measurements at a point in a three-dimensional flow is considered in the present study. The pressure probe employed was fabricated in laboratory, which was made of three cylindrical tubes aligned in a plane. Calibration of the probe was made in low-speed wind tunnel, and the physical characters of this probe such as viscous effect, applicable range of flow angle, the assumption of Reynolds number independence, are discussed. In order to get accurate and reliable velocity data, a reduction method is carefully selected based on the results of comparing with others. After the probe having been calibrated, it was employed for velocity measurement in a swirl flow. The data obtained are presented and discussed in this paper.
Book chapters on the topic "Three-hole Probes"
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Pereira, N. H. C., J. E. Borges, J. Matos, and K. Frizell. "Performance of a Combined Three-Hole Conductivity Probe for Measuring Velocity in Air-Water Jets." In Advances in Water Resources and Hydraulic Engineering, 1966–71. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-89465-0_337.
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Kienreich, I. W., N. Muhr, A. M. Veronig, D. Berghmans, A. De Groof, M. Temmer, B. Vršnak, and D. B. Seaton. "Solar TErrestrial Relations Observatory-A (STEREO-A) and PRoject for On-Board Autonomy 2 (PROBA2) Quadrature Observations of Reflections of Three EUV Waves from a Coronal Hole." In The PROBA2 Mission, 201–19. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-8187-4_12.
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Malavena, Gerardo. "Modeling of GIDL–Assisted Erase in 3–D NAND Flash Memory Arrays and Its Employment in NOR Flash–Based Spiking Neural Networks." In Special Topics in Information Technology, 43–53. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-85918-3_4.
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AbstractSince the very first introduction of three-dimensional (3–D) vertical-channel (VC) NAND Flash memory arrays, gate-induced drain leakage (GIDL) current has been suggested as a solution to increase the string channel potential to trigger the erase operation. Thanks to that erase scheme, the memory array can be built directly on the top of a $$n^+$$ n + plate, without requiring any p-doped region to contact the string channel and therefore allowing to simplify the manufacturing process and increase the array integration density. For those reasons, the understanding of the physical phenomena occurring in the string when GIDL is triggered is important for the proper design of the cell structure and of the voltage waveforms adopted during erase. Even though a detailed comprehension of the GIDL phenomenology can be achieved by means of technology computer-aided design (TCAD) simulations, they are usually time and resource consuming, especially when realistic string structures with many word-lines (WLs) are considered. In this chapter, an analysis of the GIDL-assisted erase in 3–D VC nand memory arrays is presented. First, the evolution of the string potential and GIDL current during erase is investigated by means of TCAD simulations; then, a compact model able to reproduce both the string dynamics and the threshold voltage transients with reduced computational effort is presented. The developed compact model is proven to be a valuable tool for the optimization of the array performance during erase assisted by GIDL. Then, the idea of taking advantage of GIDL for the erase operation is exported to the context of spiking neural networks (SNNs) based on NOR Flash memory arrays, which require operational schemes that allow single-cell selectivity during both cell program and cell erase. To overcome the block erase typical of nor Flash memory arrays based on Fowler-Nordheim tunneling, a new erase scheme that triggers GIDL in the NOR Flash cell and exploits hot-hole injection (HHI) at its drain side to accomplish the erase operation is presented. Using that scheme, spike-timing dependent plasticity (STDP) is implemented in a mainstream NOR Flash array and array learning is successfully demonstrated in a prototype SNN. The achieved results represent an important step for the development of large-scale neuromorphic systems based on mature and reliable memory technologies.
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Ting, T. T. C. "Anisotropic Materials with an Elliptic Boundary." In Anisotropic Elasticity. Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195074475.003.0013.
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The determination of stress distribution in a solid with the presence of a hole or an inclusion has been a mathematically interesting and challenging problem. It is also an important problem in applications. The simplest geometry of the hole is a circle. For isotropic materials a hole of arbitrary shape can be transformed, in theory, to a circle by a conformal mapping (Muskhelishvili, 1953; see also Section 3.12). Therefore a circular hole is all one needs to study for isotropic materials. For anisotropic materials there are three complex variables ɀα=x1+pαx2 (α=1,2,3). It is in general not possible to transform a hole of given shape to the same circle for all three complex variables. An exception is the ellipse (Lekhnitskii, 1950; Savin, 1961). In this chapter we study various problems involving an elliptic boundary. The ellipse can be a hole, a rigid body, or an inclusion of different anisotropic materials. We will also consider an elliptic body subjected to external forces. For anisotropic elastic materials even the circular hole needs a transformation. There is practically no difference in the analysis if the ellipse is replaced by a circle. We may employ dual coordinate systems. One coordinate system is chosen to coincide with a symmetry plane of the material when such a plane exists. The other coordinate system is to coincide with the principal axes of the ellipse. The analysis is no more complicated than when a single coordinate system is employed. For some problems employment of dual coordinate systems reveal that certain aspects of the solutions are invariant with the orientation of the ellipse in the material.
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Regis Anne W. "Energy-Efficient Mobility Heuristics for Maximizing Network Lifetime in Robotic Wireless Sensor Networks." In Advances in Wireless Technologies and Telecommunication, 426–52. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7335-7.ch019.
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In a static wireless sensor networks (WSN), the fundamental issue is the formation of energy hole in the sink's immediate locality. The solution to the energy-hole problem can be resolved by incorporating mobile entities like mobile robot (MR) into the network. This chapter proposes three strategies that exploits the mobility of the MR to overcome the energy-hole problem resulting in optimized energy usage across the network and thus maximized network lifetime. Firstly, the energy hole problem using MR is formulated as an optimization model to maximize the sojourn time of the MR at each node and a MR-ranking heuristic that ranks the critical node to be serviced is proposed. Secondly, MR-optimal scheme that finds the optimal path for the MR is formulated and designed. Thirdly, Multi-MR cooperation approach is proposed where multiple MR's collaborate to service the critical nodes. Adequate experiments have been performed to analyze the performance of the proposed schemes. The proposed methods ensure uniform energy distribution and prolonged network lifetime.
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Guendouz, Mohamed. "A Discrete Black Hole Optimization Algorithm for Efficient Community Detection in Social Networks." In Handbook of Research on Biomimicry in Information Retrieval and Knowledge Management, 133–53. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-3004-6.ch009.
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In recent years, social networks analysis has attracted the attention of many researchers. Community detection is one of the highly studied problems in this field. It is considered an NP-hard problem, and several algorithms have been proposed to solve this problem. In this chapter, the authors present a new algorithm for community detection in social networks based on the Black Hole optimization algorithm. The authors use the modularity density evaluation measure as a function to maximize. They also propose the enhancement of the algorithm by using two new strategies: initialization and evolution. The proposed algorithm has been tested on famous synthetic and real-world networks; experimental results compared with three known algorithms show the effectiveness of using this algorithm for community detection in social networks.
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Aoki, Takako, and Shin Watanabe. "Find out Mathematics on a Football: Making a football with paper." In Building on the Past to Prepare for the Future, Proceedings of the 16th International Conference of The Mathematics Education for the Future Project, King's College,Cambridge, Aug 8-13, 2022, 32–34. WTM-Verlag, 2022. http://dx.doi.org/10.37626/ga9783959872188.0.007.
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We are aiming for a workshop method as a way to teach mathematics in future school education. It is important to cooperate with each other and understand mathematics. In this workshop, we aim to discover the mathematics hidden in the footballs we handle every day. As an aid to thinking, I would like to make football by paper first and learn mathematics while looking at concrete things. You need 20 equilateral triangles. A regular hexagon is made from this equilateral triangle, and a regular pentagon uses the method of making a hole. In particular, pay attention to the four-color problem in mathematics, make sure that the colours of adjacent regular hexagons are different, and use three colours (red, green, yellow). For example, in a football, how many equilateral triangles of each colour are used is one of the issues. I am looking forward to holding a workshop to see what kind of problems there are. Key words: football Introduction with paper, the truncated icosahedron, the color coding of the three colors, Euler's polyhedral formula
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Stowasser, Sascha, and Nicole Ottersböck. "Competence Development within Hybrid Value Creation - Need-based Competence Development for the Successful Implementation of Hybrid, Data-Driven Business Models." In Competence development and learning assistance systems for the data-driven future, 143–60. Goto Verlag, 2021. http://dx.doi.org/10.30844/wgab_2021_9.
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Digitalization and the increasing technical possibilities of networking machines and products as well as the use of large amount of data in the hole production process offer companies the opportunity to establish new, so-called hybrid business models. This enables them to provide customers data-driven, smart services in addition to their physical products, create more value and strengthen their competitiveness. The hybridization of value creation is accompanied by numerous changes and new competence requirements in companies, which need to be shaped socio-technically. In the AnGeWaNt project, such hybrid business models were developed and implemented in three companies. The article describes the approach to analyzing and shaping changes and competence requirements that arise in companies as a result of digitalization and hybridization.
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Motoko, Ueyama. "New Approach to Teaching Japanese Pronunciation in the Digital Era." In Ca’ Foscari Japanese Studies. Venice: Fondazione Università Ca’ Foscari, 2020. http://dx.doi.org/10.30687/978-88-6969-428-8/010.
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Pronunciation has been a black hole in the L2 Japanese classroom on account of a lack of class time, teacher’s confidence, and consciousness of the need to teach pronunciation, among other reasons. The absence of pronunciation instruction is reported to result in fossilized pronunciation errors, communication problems, and learner frustration. With an intention of making a contribution to improve such circumstances, this paper aims at three goals. First, it discusses the importance, necessity, and effectiveness of teaching prosodic aspects of Japanese pronunciation from an early stage in acquisition. Second, it shows that Japanese prosody is challenging because of its typological rareness, regardless of the L1 backgrounds of learners. Third and finally, it introduces a new approach to teaching L2 pronunciation with the goal of developing L2 comprehensibility by focusing on essential prosodic features, which is followed by discussions on key issues concerning how to implement the new approach both inside and outside the classroom in the digital era.
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Carty, Alistair. "3D Laser Scanning at Church Hole, Creswell Crags." In Palaeolithic Cave Art at Creswell Crags in European Context. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780199299171.003.0009.
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The process of recording in situ archaeological art can be a time-consuming and complex task, especially on inaccessible and non-planar surfaces such as those found in Church Hole, Creswell Crags. There are considerable challenges to the recorder, including the accurate positioning and fixing of survey frames, the physical discomfort of sitting, crouching, or even lying down for long periods of time in cramped surroundings, and, ultimately, the difficulty in interpreting the panels to enable accurate recording. Furthermore, the more accurate forms of traditional recording include the taking of rubbings of the carvings, a process known to increase the potential of damage to already fragile artworks. 3D laser scanning offers solutions to most of these problems by quickly producing a highly dense fully three-dimensional surface map of the art which can be studied in more conducive circumstances by researchers at a later date. Furthermore, powerful visualization techniques can be applied to the 3D surface map to extract and enhance detail that might be virtually invisible to the naked eye. Over-arching the visualization and interpretational aspects of 3D laser scanning is the potential to use the acquired 3D surface map to monitor any change in the surface through repeated scanning over a period of time. This technique is suitable for detecting minute differences in the surface over time, including both erosion due to natural processes or vandalism and accretion through build-up of deposits on the surface of the art. The most complex aspect of three-dimensional recording, no matter what the subject matter, is that of the third dimension. People have an almost schizophrenic way of looking at the world. For example, if you were to place two identical objects a distance apart, it is simple to state that one object is further away than the other due to our perception of depth and the ability to walk around the two objects. However, if you were to take a photograph or make a drawing of the scene from one point of view, it becomes difficult to tell whether two identical objects are placed some distance apart, or if two differently sized objects sit beside one another. The three-dimensionality of the scene is now lost and is available by inference only.
Conference papers on the topic "Three-hole Probes"
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Dell’Era, Giulia, Mehmet Mersinligil, and Jean-François Brouckaert. "Assessment of Unsteady Pressure Measurement Uncertainty: Part 2 — Virtual Three Hole Probe." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42615.
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With the advancements in miniaturization and temperature capabilities of piezo-resistive pressure sensors, pneumatic probes — which are the long established standard for flow-path pressure measurements in gas turbine environments — are being replaced with unsteady pressure probes. On the other hand, any measured quantity is by definition inherently different from the ‘true’ value, requiring the estimation of the associated errors for determining the validity of the results and establishing respective confidence intervals. In the context of pressure measurements, the calibration uncertainty values, which differ from measurement uncertainties, are typically provided. Even then, the lack of a standard methodology is evident as uncertainties are often reported without appropriate confidence intervals. Moreover, no time-resolved measurement uncertainty analysis has come to the attention of the authors. The objective of this paper is to present a standard method for the estimation of the uncertainties related to measurements performed using single sensor unsteady pressure probes, with the help of measurements obtained in a one and a half stage low pressure high speed axial compressor test rig as an example. The methodology presented is also valid for similar applications involving the use of steady or unsteady sensors and instruments. The static calibration uncertainty, steady measurement uncertainties and unsteady measurement uncertainties based on phase-locked and ensemble averages are presented by the authors in [1]. Depending on the number of points used for the averaging, different values for uncertainty have been observed, underlining the importance of having greater number of samples. For unsteady flows, higher uncertainties have been observed at regions of higher unsteadiness such as tip leakage vortices, hub corner vortices and blade wakes. Unfortunately, the state of the art in single-sensor miniature unsteady pressure probes is comparable to multi-hole pneumatic probes in size, preventing the use of multi-hole unsteady probes in turbomachinery environments. However, the angular calibration properties of a single sensor probe obtained via an aerodynamic calibration may further be exploited as if a three-hole directional probe is employed, yielding corrected total pressure, unsteady yaw angle, static pressure and Mach number distributions based on the phase-locked averages with the expense of losing the time-correlation between the virtual ports. The aerodynamic calibration and derivation process are presented together with the assessment of the uncertainties associated to these derived quantities in this contribution. In the virtual three-hole mode, similar to that of a single-sensor probe, higher uncertainty values are observed at regions of higher unsteadiness.
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Grimshaw, S. D., and J. V. Taylor. "Fast Settling Millimetre-Scale Five-Hole Probes." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56628.
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This paper investigates how the external geometry of a five-hole probe affects its accuracy and how internal geometry affects its settling time. An analytical model, which predicts settling time, is used to design an accurate, fast-settling, millimetre-scale probe. The paper has three components: First, results are presented from a series of area traverses performed with five-hole probes which range in head diameter from 0.99 to 2.67 mm. It is found that the smallest probe gives the greatest accuracy when traversing the shear layers in blade wakes. However, it takes 3.4 times longer to complete this traverse than compared to the largest probe. This is because traverses with small probes require more time to allow the pressure readings to settle between each traverse position. Second, an analytical model is developed which predicts settling time based upon the internal geometry of the probe. The approach adopted is capable of modeling any number of connected tubes with different lengths and diameters. It is validated against experimental measurements and is shown to give good agreement. This model can be used to ensure that probes are designed with acceptable settling times. Finally, the analytical model is used to design an optimised five hole probe. Use of the model highlights two important results which are required to reduce settling time: First, the length of the smallest diameter tubes, i.e. the ones in the probe head, should be minimised. Second, the volume of tubing downstream of the head should be minimised. Applying these principles to a new probe design cuts the total traverse time by 71%, whilemaintaining the highest value of accuracy.
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Hoenen, Herwart T., Robert Kunte, Phillip Waniczek, and Peter Jeschke. "Measuring Failures and Correction Methods for Pneumatic Multi-Hole Probes." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-68113.
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Systematic measurements have been performed in a free stream in order to analyse the measuring behaviour of pneumatic multi-hole probes in the gradient field of a wake of an airfoil. The five-hole probe was traversed in different axial distances from the trailing edge and the results were compared to PIV and hot film probe measurements. The direct comparison of the three measurement techniques shows that too small axial distances between a five-hole probe and an airfoil trailing edge introduce significant measurement errors. Different effects were analysed in order to evaluate their influence on the measuring results and to estimate the deviation from the real flow properties. The limitations of probe measurements and the influences of the probe on the flow field are discussed. It is explained how pneumatic multi-hole probe measuring data can be corrected in order to improve the measuring results. In order to demonstrate the suitability of the correction method for turbo machinery application it is applied to measurement results of an axial compressor test rig.
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Argu¨elles Di´az, Katia Mari´a, Jesu´s Manuel Ferna´ndez Oro, Eduardo Blanco Marigorta, and Rau´l Barrio Perotti. "A Numerical 3-D Model of a Trapezoidal Three-Hole Pneumatic Pressure Probe for Incompressible Flow." In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30713.
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Pneumatic pressure probes are well-mature measuring devices to characterize both pressure and velocity fields for external and internal flows. The measuring range of a particular probe is significantly influenced by important factors, like its geometry, the separation angle between the holes, the holes tapping or even flow conditions like separation and stagnation points or the local Reynolds number. Ideally, every pressure probe must be specifically designed for the particular application where it is needed. However, this procedure requires a detailed calibration of the probe for the whole expected range of velocities and incidences. This implies an important cost in both economic terms and operating times. Thus, the definition of an accurate numerical model for the design and calibration of pressure probes at different flow conditions is particularly desirable for these purposes. The first step towards the establishment of this useful methodology is the development of a reliable model to predict numerically the probe measuring characteristics. Thus, in this paper a numerical 3-D model is presented to characterize the calibration of a three-hole pneumatic pressure probe. In particular, a trapezoidal geometry with a 60 degree angle between the holes is considered here. The simulation of the flow incidence is carried out using the commercial code FLUENT, analyzing the influence of different mesh densities and turbulence models. The complete set of numerical cases includes different flow velocities and several yaw angles. The numerical results have been validated using experimental results obtained in a calibration facility, focusing on the definition of a numerical tool for the design and calibration of three-hole pneumatic probes under incompressible flow conditions.
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Franken, Arnoud R. C., and Paul C. Ivey. "Accelerating the Calibration of Multi-Hole Pressure Probes by Applying Advanced Computational Methods." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53434.
Full textAbstract:
The miniature multi-hole pneumatic pressure probe is widely regarded as a cost-effective, easy-to-use and accurate method for performing two- or three-dimensional flow field measurements in turbomachinery. The major downside to the use of these probes is that the influence of fabrication imperfections on probe characteristics necessitates an extensive and highly time-intensive and, therefore, costly calibration of each individual probe. Unless these probes can be fabricated to such standards that make individual probe calibrations superfluous, the only way to significantly reduce the time and costs associated with probe calibration is to shorten the calibration process. The latter is only possible if all essential information can be obtained from less calibration data. This paper describes a novel approach to the calibration of a series of multi-hole pressure probes in which advanced computational methods are used to make this possible. By exploiting the key features of a probe’s characteristic this approach requires only a fraction of the size of a conventional calibration database for the accurate modeling of the relationships between port pressures and flow conditions. As a result, calibration time and costs can be reduced without the sacrifice of quality.
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Conlon, Martin J., Alexander Wright, and Hamza M. Abo El Ella. "Measurement of Large Flow Angles With Non-Nulling Multi-Hole Pressure Probes." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-64932.
Full textAbstract:
In complex flow fields, the steady-state, three-dimensional attributes can be measured intrusively using a multi-hole pressure probe. These probes are built to be as small as possible to minimize flow disturbance, but the small size makes them susceptible to both manufacturing tolerances and fouling. As such, each probe must be calibrated on a regular basis and care must be taken to ensure that the geometry is not disturbed. The probes are operated in either “nulling” or “non-nulling” modes, the latter being the simpler of the two in terms of experimental setup and mechanical fixturing. This has made non-nulling mode the preferred choice for many years; however, non-nulling mode necessitates complete three-dimensional calibration data. Sector-based calibration strategies have become nearly universal, although improvement efforts continue. This paper presents a new calibration and data analysis strategy that gives shorter calibration times and more robust data reduction.
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El-Shahat, Saeed A., Hesham M. El-Batsh, Ali M. A. Attia, Guojun Li, and Lei Fu. "Investigations of Three-Dimensional Flow Field Development in an Axial Compressor Cascade." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11047.
Full textAbstract:
Abstract This paper presents a complete study about three-dimensional (3-D) flow field development in a linear compressor cascade where flow field in the blade passage has been studied experimentally as well as numerically. In the experimental work, a linear compressor cascade test section was installed in an open loop wind tunnel. The experimental data was acquired for a Reynolds number of 2.98 × 105 based on the blade chord and the inlet flow conditions. The flow field characteristics in blade passage including 3-D flow velocity and velocity magnitude have been measured by using calibrated five and seven-hole pressure probes connected to ATX sensor module data acquisition system (DAQ). To investigate flow development in the blade passage, velocity coefficient through streamwise planes has been calculated from the measured data. The computational fluid dynamics (CFD) study of the flow field was performed to gain a better understanding of the flow features. Present computational study was first validated with previous experimental and numerical work to check mesh accuracy and give confidence for computational results. Then, two turbulence models, Spalart-Allmaras (S-A) and shear stress transport SST (k-ω) were used for the present work. From both parts of study, the flow field development through the cascade have been investigated and compared. Moreover, the received data demonstrated a good agreement between the experimental and computational results. The predicted flow streamlines by numerical calculations showed regions characterized by flow separation and recirculation zones such as corner separation that could be used to enhance the understanding of the loss mechanism in compressor cascades. All measurements taken by the two probes, 5 and 7-hole pressure probes, have been analyzed and compared. The 5-hole pressure probe measurements have showed more agreements with computational results than 7-hole probe. Furthermore S-A turbulence model calculations showed more consistencies with experimental results than SST (k-ω) model.
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Coldrick, Simon, Paul Ivey, and Roger Wells. "Considerations for Using 3D Pneumatic Probes in High Speed Axial Compressors." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30045.
Full textAbstract:
This paper describes preparatory work towards three dimensional flowfield measurements downstream of the rotor in an industrial, multistage, axial compressor, using a pneumatic pressure probe. The probe is of the steady state four hole cobra probe type. The design manufacture and calibration of the probe is described. CFD calculations have been undertaken in order to assess the feasability of using such a probe in the high speed compressor environment where space is limited. This includes effects of mounting the probe in close proximity to the downstream stator blades and whether it is necessary to adjust the calibration data to compensate for these effects.
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Dell’Era, Giulia, Mehmet Mersinligil, and Jean-François Brouckaert. "Assessment of Unsteady Pressure Measurement Uncertainty: Part 1 — Single Sensor Probe." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42608.
Full textAbstract:
With the advancements in miniaturization and temperature capabilities of piezo-resistive pressure sensors, pneumatic probes — which are the long established standard for flow-path pressure measurements in gas turbine environments — are being replaced with unsteady pressure probes. Any measured quantity is by definition inherently different from the ‘true’ value, requiring the estimation of the associated errors for determining the validity of the results and establishing respective confidence intervals. In the context of pressure measurements, the calibration uncertainty values, which differ from measurement uncertainties, are typically provided. Even then, the lack of a standard methodology is evident as uncertainties are often reported without appropriate confidence intervals. Moreover, no time-resolved measurement uncertainty analysis has come to the attention of the authors. The objective of this paper is to present a standard method for the estimation of the uncertainties related to measurements performed using single sensor unsteady pressure probes, with the help of measurements obtained in a one and a half stage low pressure high speed axial compressor test rig as an example. The methodology presented is also valid for similar applications involving the use of steady or unsteady sensors and instruments. The static calibration uncertainty, steady measurement uncertainties and unsteady measurement uncertainties based on phase-locked and ensemble averages are presented in this contribution. Depending on the number of points used for the averaging, different values for uncertainty have been observed, underlining the importance of having greater number of samples. For unsteady flows, higher uncertainties have been observed at regions of higher unsteadiness such as tip leakage vortices, hub corner vortices and blade wakes. Unfortunately, the state of the art in single-sensor miniature unsteady pressure probes is comparable to multi-hole pneumatic probes in size, preventing the use of multi-hole unsteady probes in turbomachinery environments. However, the angular calibration properties of a single sensor probe obtained via an aerodynamic calibration may further be exploited as if a three-hole directional probe is employed, yielding corrected total pressure, unsteady yaw angle, static pressure and Mach number distributions based on the phase-locked averages with the expense of losing the time-correlation between the virtual ports. The aerodynamic calibration and derivation process are presented together with the assessment of the uncertainties associated to these derived quantities by the authors in [1]. In the virtual three-hole mode, similar to that of a single-sensor probe, higher uncertainty values are observed at regions of higher unsteadiness.
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Giel, P. W., D. R. Thurman, I. Lopez, R. J. Boyle, G. J. Van Fossen, T. A. Jett, W. P. Camperchioli, and H. La. "Three-Dimensional Flow Field Measurements in a Transonic Turbine Cascade." In ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-113.
Full textAbstract:
Three-dimensional flow field measurements are presented for a large scale transonic turbine blade cascade. Flow field total pressures and pitch and yaw flow angles were measured at an inlet Reynolds number of 1.0 × 106 and at an isentropic exit Mach number of 1.3 in a low turbulence environment. Flow field data was obtained on five pitchwise/spanwise measurement planes, two upstream and three downstream of the cascade, each covering three blade pitches. Three-hole boundary layer probes and five-hole pitch/yaw probes were used to obtain data at over 1200 locations in each of the measurement planes. Blade and endwall static pressures were also measured at an inlet Reynolds number of 0.5 × 106 and at an isentropic exit Mach number of 1.0. Tests were conducted in a linear cascade at the NASA Lewis Transonic Turbine Blade Cascade Facility. The test article was a turbine rotor with 136° of turning and an axial chord of 12.7 cm. The flow field in the cascade is highly three-dimensional as a result of thick boundary layers at the test section inlet and because of the high degree of flow turning. The large scale allowed for very detailed measurements of both flow field and surface phenomena. The intent of the work is to provide benchmark quality data for CFD code and model verification.
Reports on the topic "Three-hole Probes"
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NUMERICAL STUDY ON SHEAR BEHAVIOUR OF ENHANCED C-CHANNELS IN STEEL-UHPC-STEEL SANDWICH STRUCTURES. The Hong Kong Institute of Steel Construction, September 2021. http://dx.doi.org/10.18057/ijasc.2021.17.3.4.
Full textAbstract:
This paper firstly developed a three-dimensional (3D) finite element model (FEM) for enhanced C-channels (ECs) in steel-UHPC-steel sandwich structures (SUSSSs). The FEM was validated by 12 push-out tests on ECs with UHPC. With the validated FEM, this paper performed in-depth parametric studies on shear behaviours of ECs with ultra-high performance concrete (UHPC). These investigated parameters included bolt-hole gap (a), grade (M) and diameter (d) of bolt, core strength (fc), length of C-channel (Lc), and prestressing force ratio on bolt (ρ) in ECs. Under shear forces, the ECs in UHPC exhibited successive fractures of bolts and C-channels. Increasing the bolt-hole gap within 0-2 mm has no harm on the ultimate shear resistance, but greatly improves the slip capacity of ECs. Increasing grade and diameter of bolts improves the shear resistance and ductility of ECs through increasing the PB/PC (shear strength of bolt to that of C-channel) ratio. Increasing the core strength increased the shear resistance, but reduced the ductility of ECs due to the reduced PB/PC ratio. The ECs with Lc value of 50 mm offer the best ductility. Prestressing force acting on the bolts reduced the shear strength and ductility of ECs with UHPC. Analytical models were proposed to estimate the ultimate shear resistance and shear-slip behaviours of ECs with UHPC. The extensive validations of these models against 12 tests and 31 FEM analysis cases proved their reasonable evaluations on shear behaviours of ECs with UHPC.