Journal articles on the topic 'Pipe-like structures'
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1
Leonard, Kevin R., and Mark K. Hinders. "Lamb wave tomography of pipe-like structures." Ultrasonics 43, no. 7 (June 2005): 574–83. http://dx.doi.org/10.1016/j.ultras.2004.12.006.
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Okudan, Gorkem, Hrishikesh Danawe, Lu Zhang, Didem Ozevin, and Serife Tol. "Enhancing Acoustic Emission Characteristics in Pipe-Like Structures with Gradient-Index Phononic Crystal Lens." Materials 14, no. 6 (March 22, 2021): 1552. http://dx.doi.org/10.3390/ma14061552.
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Phononic crystals have the ability to manipulate the propagation of elastic waves in solids by generating unique dispersion characteristics. They can modify the conventional behavior of wave spreading in isotropic materials, known as attenuation, which negatively influences the ability of acoustic emission method to detect active defects in long-range, pipe-like structures. In this study, pipe geometry is reconfigured by adding gradient-index (GRIN) phononic crystal lens to improve the propagation distance of waves released by active defects such as crack growth and leak. The sensing element is designed to form a ring around the pipe circumference to capture the plane wave with the improved amplitude. The GRIN lens is designed by a special gradient-index profile with varying height stubs adhesively bonded to the pipe surface. The performance of GRIN lens for improving the amplitude of localized sources is demonstrated with finite element numerical model using multiphysics software. Experiments are conducted using pencil lead break simulating crack growth, as well as an orifice with pressured pipe simulating leak. The amplitude of the burst-type signal approximately doubles on average, validating the numerical findings. Hence, the axial distance between sensors can be increased proportionally in the passive sensing of defects in pipe-like geometries.
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Shah, Darshita, Jatin Dave, Ashish Majithiya, and Yash Patel. "Conceptual Design and Analysis of Pipe Climbing Robot." Journal of Physics: Conference Series 2115, no. 1 (November 1, 2021): 012004. http://dx.doi.org/10.1088/1742-6596/2115/1/012004.
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Abstract Robotics is one of the most emerging technologies in the current scenario. In this fast-growing technological world automation through robotics finds its place in almost all the fields. Climbing robots became more popular due to their versatile applications like inspection of tall buildings, tanks, structures, facade cleaning, fruits harvesting on tall trees (coconut) and many more. It became most adaptive as working on height may lead to dangerous incidents for human beings. Operations like visual inspection, crack detection of tall structures and pipes can be made possible with specially designed pipe climber robot. It finds its applications where human cannot reach, like hazardous applications. Specially design robots for a specific application also performs well with precision. This paper presents the novel design and analysis of pipe climbing robot for Chemical plant pipeline fault and leakage detection purpose. Design of all components of the robot is done with the basic mathematical consideration and then its analysis is carried out using FEA tools and MATLAB. Results of Forward and Inverse kinematic analysis of robot are obtained for certain specific points of trajectory. Dynamic analysis has been performed for motor selection and torque calculation. Presented conceptual design and analysis can be useful for pipe inspection purpose.
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Vappangi, Pradeep Kumar, and Naganjaneyulu Kasturi. "New Methodology in Interpretation of Aeromagnetic Anomalies over Pipe-Like Sources using Analytic Signal Ratio Approach." Trends in Sciences 19, no. 24 (November 18, 2022): 2119. http://dx.doi.org/10.48048/tis.2022.2119.
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Concepts of signal processing like Fourier transform, filtering, power spectrum, derivatives etc., are widely used in geophysical models in exploring the Earth structures. For example, quantitative interpretation of aeromagnetic maps is based mainly on choosing an appropriate model for evaluating parameters of the causative source. For circular or elliptical anomalies caused by plug-like intrusive sources, the vertical pipe of infinite depth extent (also known as single or mono pole) is most suited. It is also more common to use analytic signal maps in interpretation. For a vertical pipe, the total magnetic intensity (TMI) anomaly is anti-symmetric at the magnetic equator and progressively becomes symmetric at the pole. Based on this property, a new methodology is developed for identifying location and depth of magnetic structures beneath. It is concluded that the analytic signal is almost symmetric for any magnetic latitude and by using both the properties of the anomaly and its analytic signal the location and depth can be evaluated. This new approach is validated by field examples. HIGHLIGHTS The theory and application of using analytic signal to determine the location and depth to the point pole is described The method is useful in locating pipe-like (vertical cylinder, kimberlite pipes) structures The shape of the magnetic anomaly changes with magnetic inclination whereas the analytic signal map is symmetric and almost circular, with its maximum centred over the top of the pipe The analytic signal is almost symmetric for any magnetic latitude and by using both the properties of the anomaly and its analytic signal, the location and depth to the top can be evaluated GRAPHICAL ABSTRACT
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Chen, Xue Feng, Bing Li, and Zheng Jia He. "Crack Detection in Pipe Structures by Lifting Wavelet Finite Element Method." Key Engineering Materials 413-414 (June 2009): 143–50. http://dx.doi.org/10.4028/www.scientific.net/kem.413-414.143.
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Due to the fact that near a crack singularity, gradients of the solution are large and are also subject to abrupt changes, so that the solution cannot locally be accurately approximated by a piecewise polynomial function on a quasi-uniform mesh. Lifting wavelet finite element has good ability in modal analysis for singularity problems like a cracked pipe. The first three natural frequencies of the cracked pipe were solved with lifting wavelet finite element, and the database for crack diagnosis was obtained. The first three measured natural frequencies were employed as inputs and the intersection of the three frequencies contour lines predicted the normalized crack location and size. The experimental examples denote the method is of higher identification precision.
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Ergene, Berkay, İsmet ŞEKEROĞLU, Çağın Bolat, and Bekir Yalçın. "An experimental investigation on mechanical performances of 3D printed lightweight ABS pipes with different cellular wall thickness." Journal of Mechanical Engineering and Sciences 15, no. 2 (June 10, 2021): 8169–77. http://dx.doi.org/10.15282/jmes.15.2.2021.16.0641.
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In recent years, cellular structures have attracted great deal of attention of many researchers due to their unique properties like exhibiting high strength at low density and great energy absorption. Also, the applications of cellular structures (or lattice structures) such as wing airfoil, tire, fiber and implant, are mainly used in aerospace, automotive, textile and biomedical industries respectively. In this investigation, the idea of using cellular structures in pipes made of acrylonitrile butadiene styrene (ABS) material was focused on and four different pipe types were designed as honeycomb structure model, straight rib pattern model, hybrid version of the first two models and fully solid model. Subsequently, these models were 3D printed by using FDM method and these lightweight pipes were subjected to compression tests in order to obtain stress-strain curves of these structures. Mechanical properties of lightweight pipes like elasticity modulus, specific modulus, compressive strength, specific compressive strength, absorbed energy and specific absorbed energy were calculated and compared to each other. Moreover, deformation modes were recorded during all compression tests and reported as well. The results showed that pipe models including lattice wall thickness could be preferred for the applications which don’t require too high compressive strength and their specific energy absorption values were notably capable to compete with fully solid pipe structures. In particular, rib shape lattice structure had the highest elongation while the fully solid one possessed worst ductility. Lastly, it is pointed out that 3D printing method provides a great opportunity to have a foresight about production of uncommon parts by prototyping.
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EIFF, OLIVIER S., and JAMES F. KEFFER. "On the structures in the near-wake region of an elevated turbulent jet in a crossflow." Journal of Fluid Mechanics 333 (February 25, 1997): 161–95. http://dx.doi.org/10.1017/s0022112096004314.
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A pattern-recognition technique, applied to multi-point simultaneous velocity measurements obtained with 45° X-wire anemometer probes, is used to extract and characterize the underlying organized motions, i.e. coherent structures, within the near-wake region of a turbulent round jet discharged perpendicularly from a pipe into a crossflow. This flow has been found to be quite complex owing to its three-dimensional nature and the interactions between several flow regions. Analyses of the underlying coherent structures, which play an important role in the physics of the flow, are still rare and are mostly based on flow-visualization techniques. Using a pattern-recognition technique in conjunction with hot-wire measurements, we recently examined the wake regions of the pipe and jet at levels near the tip of the pipe, and found that Kármán-like vortex structures in the wake of the pipe are locked to similar structures in the jet-wake. In this paper we expand upon our previous work and characterize these structures throughout the wake of the jet up into the region of the bent-over jet – a region where they have not been identified previously. The complex geometry of these structures in the wake of the jet as well as their interaction with the bent-over jet are discussed. The results show that these structures split before they link to similar structures on the opposite side of the symmetry plane in the jet region. The results further suggest that the vorticity due to the structures in the wake of the jet contributes to the motion of the well-known counter-rotating vortex pair.
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Danawe, Hrishikesh, Gorkem Okudan, Didem Ozevin, and Serife Tol. "Conformal gradient-index phononic crystal lens for ultrasonic wave focusing in pipe-like structures." Applied Physics Letters 117, no. 2 (July 13, 2020): 021906. http://dx.doi.org/10.1063/5.0012316.
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Lee, Hyung Yil, Jin Haeng Lee, and Tae Hyung Kim. "Failure Assessment Diagrams of Semi-Elliptical Surface Crack with Constraint Effect." Key Engineering Materials 353-358 (September 2007): 1952–55. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.1952.
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For accurate failure assessment, a second parameter like T-stress describing the constraint is needed in addition to the single parameter J-integral. In this work, selecting the structures of surface-cracked plate and pipe, we perform line-spring finite element modeling, and accompanying elastic-plastic finite element analyses. We then present a framework, which includes the constraint effects in the R6 FAD approach for failure assessment of cracked-structures.
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Lee, Hyung Yil, Jin Haeng Lee, and Tae Hyung Kim. "Failure Assessment Diagrams of Semi-Elliptical Surface Crack with Constraint Effect." Key Engineering Materials 353-358 (September 2007): 98–101. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.98.
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For accurate failure assessment, a second parameter like T-stress describing the constraint is needed in addition to the single parameter J-integral. In this work, selecting the structures of surface-cracked plate and pipe, we perform line-spring finite element modeling, and accompanying elastic-plastic finite element analyses. We then present a framework, which includes the constraint effects in the R6 FAD approach for failure assessment of cracked-structures.
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Ozcakir, Ozge, Saleh Tanveer, Philip Hall, and Edward A. Overman. "Travelling wave states in pipe flow." Journal of Fluid Mechanics 791 (February 22, 2016): 284–328. http://dx.doi.org/10.1017/jfm.2015.751.
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In this paper, we have found two new nonlinear travelling wave solutions in pipe flows. We investigate possible asymptotic structures at large Reynolds number $R$ when wavenumber is independent of $R$ and identify numerically calculated solutions as finite $R$ realizations of a nonlinear viscous core (NVC) state that collapses towards the pipe centre with increasing $R$ at a rate $R^{-1/4}$. We also identify previous numerically calculated states as finite $R$ realizations of a vortex wave interacting (VWI) state with an asymptotic structure similar to the ones in channel flows studied earlier by Hall & Sherwin (J. Fluid Mech., vol. 661, 2010, pp. 178–205). In addition, asymptotics suggests the possibility of a VWI state that collapses towards the pipe centre like $R^{-1/6}$, though this remains to be confirmed numerically.
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Hernandez Perez, V., B. J. Azzopardi, R. Kaji, M. J. da Silva, M. Beyer, and U. Hampel. "Wisp-like structures in vertical gas–liquid pipe flow revealed by wire mesh sensor studies." International Journal of Multiphase Flow 36, no. 11-12 (November 2010): 908–15. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2010.08.002.
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Barkley, D. "Taming turbulent fronts by bending pipes." Journal of Fluid Mechanics 872 (June 4, 2019): 1–4. http://dx.doi.org/10.1017/jfm.2019.340.
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The flow of fluid through a pipe has been instrumental in illuminating the subcritical route to turbulence typical of many wall-bounded shear flows. Especially important in this process are the turbulent–laminar fronts that separate the turbulent and laminar flow. Four years ago Michael Graham (Nature, vol. 526, 2015, p. 508) wrote a commentary entitled ‘Turbulence spreads like wildfire’, which is a picturesque but also accurate characterisation of the way turbulence spreads through laminar flow in a straight pipe. In this spirit, the recent article by Rinaldi et al. (J. Fluid Mech., vol. 866, 2019, pp. 487–502) shows that turbulent wildfires are substantially tamed in bent pipes. These authors find that even at modest pipe curvature, the characteristic strong turbulent–laminar fronts of straight pipe flow vanish. As a result, the propagation of turbulent structures is modified and there are hints that the route to turbulence is fundamentally altered.
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WILLIS, ASHLEY P., and RICH R. KERSWELL. "Turbulent dynamics of pipe flow captured in a reduced model: puff relaminarization and localized ‘edge’ states." Journal of Fluid Mechanics 619 (January 25, 2009): 213–33. http://dx.doi.org/10.1017/s0022112008004618.
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Fully three-dimensional computations of flow through a long pipe demand a huge number of degrees of freedom, making it very expensive to explore parameter space and difficult to isolate the structure of the underlying dynamics. We therefore introduce a ‘2+ε-dimensional’ model of pipe flow, which is a minimal three-dimensionalization of the axisymmetric case: only sinusoidal variation in azimuth plus azimuthal shifts are retained; yet the same dynamics familiar from experiments are found. In particular the model retains the subcritical dynamics of fully resolved pipe flow, capturing realistic localized ‘puff-like’ structures which can decay abruptly after long times, as well as global ‘slug’ turbulence. Relaminarization statistics of puffs reproduce the memoryless feature of pipe flow and indicate the existence of a Reynolds number about which lifetimes diverge rapidly, provided that the pipe is sufficiently long. Exponential divergence of the lifetime is prevalent in shorter periodic domains. In a short pipe, exact travelling-wave solutions are found near flow trajectories on the boundary between laminar and turbulent flow. In a long pipe, the attracting state on the laminar–turbulent boundary is a localized structure which resembles a smoothened puff. This ‘edge’ state remains localized even for Reynolds numbers at which the turbulent state is global.
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Zhang, Bing, Timothy P. Waters, and Brian R. Mace. "Identifying joints from measured reflection coefficients in beam-like structures with application to a pipe support." Mechanical Systems and Signal Processing 24, no. 3 (April 2010): 784–95. http://dx.doi.org/10.1016/j.ymssp.2009.10.023.
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Chan, Derek, Chaminda Pathma Kumara Gallage, Pathmanathan Rajeev, and Jayantha Kodikara. "Field performance of in-service cast iron water reticulation pipe buried in reactive clay." Canadian Geotechnical Journal 52, no. 11 (November 2015): 1861–73. http://dx.doi.org/10.1139/cgj-2014-0531.
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Field monitoring is an important means for understanding soil behaviour and its interaction with buried structures such as pipeline. This paper details the successful instrumentation of a section of an in-service cast iron water main buried in an area of reactive clay where frequent water pipe breakage has been observed. The instrumentation included measurement of pipe strain; pipe water pressure and temperature; soil pressure, temperature, moisture content, and matric suction; as well as the meteorological conditions on site. The data generally indicated that changes in soil temperature, suction, and moisture content were directly related to the local climatic variations. The suction and moisture content data indicated that the soil profile at the site down to around 700 mm, and probably down to 1000 mm, is affected by changes in surface weather, while soil conditions below this depth appear to be more stable. Analysis of pipe strain indicated that the pipe behaves like a cantilever beam, with the top experiencing predominantly tensile strains during summer. Subsequently, these trends reduce to compressive strains as soil swelling occurs because of the increase of moisture content with the onset of winter.
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Li, Weibin, Mingxi Deng, and Younho Cho. "Cumulative Second Harmonic Generation of Ultrasonic Guided Waves Propagation in Tube-Like Structure." Journal of Computational Acoustics 24, no. 03 (August 30, 2016): 1650011. http://dx.doi.org/10.1142/s0218396x16500119.
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Second harmonic generation of ultrasonic waves propagating in unbounded media and plate-like structure has been vigorously studied for tracking material nonlinearity, however, second harmonic guided wave propagation in tube-like structures is rarely studied. Considering that second harmonics can provide sensitive information for structural health condition, this paper aims to study the second harmonic generation of guided waves in metallic tube-like structures with weakly nonlinearity. Perturbation method and modal analysis approach are used to analyze the acoustic field of second harmonic solutions. The conditions for generating second harmonics with cumulative effect are provided in present investigation. Flexible polyvinylidene fluoride comb transducers are used to measure fundamental wave modes and second harmonic ones. The work experimentally verifies that the second harmonics of guided waves in pipe have a cumulative effect with propagation distance. The proposed procedure of this work can be applied to detect material nonlinearity due to damage mechanism in tube-like structure.
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Longtin, J. P., B. Badran, and F. M. Gerner. "A One-Dimensional Model of a Micro Heat Pipe During Steady-State Operation." Journal of Heat Transfer 116, no. 3 (August 1, 1994): 709–15. http://dx.doi.org/10.1115/1.2910926.
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Micro heat pipes are small structures that will be used to cool microscale devices. They function much like their conventional counterparts, with a few exceptions, most notably the absence of a wick. It is expected that water-filled micro heat pipes will be able to dissipate heat fluxes on the order of 10–15 W/cm2 (100,000–150,000 W/m2). This work addresses the modeling of a micro heat pipe operating under steady-state conditions. A one-dimensional model of the evaporator and adiabatic sections is developed and solved numerically to yield pressure, velocity, and film thickness information along the length of the pipe. Interfacial and vapor shear stress terms have been included in the model. Convection and body force terms have also been included in the momentum equation, although numerical experiments have shown them to be negligible. Pressure, velocity, and film thickness results are presented along with the maximum heat load dependence on pipe length and width. Both simple scaling and the model results show that the maximum heat transport capability of a micro heat pipe varies with the inverse of its length and the cube of its hydraulic diameter, implying the largest, shortest pipes possible should be used.
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Armbrecht, G., E. Denicke, I. Rolfes, N. Pohl, T. Musch, and B. Schiek. "Compact mode-matched excitation structures for radar distance measurements in overmoded circular waveguides." Advances in Radio Science 6 (May 26, 2008): 9–17. http://dx.doi.org/10.5194/ars-6-9-2008.
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Abstract. This contribution deals with guided radar level measurements of liquid materials in large metal tubes, so-called stilling wells, bypass or still pipes. In the RF domain these tubes function as overmoded circular waveguides and mode-matched excitation structures like waveguide tapers are needed to avoid higher order waveguide modes. Especially for high-precision radar measurements the multimode propagation effects need to be minimized to achieve submillimeter accuracy. Therefore, a still pipe simulator is introduced with the purpose to fundamentally analyze the modal effects. Furthermore, a generalized design criterion is derived for the spurious mode suppression of compact circular waveguide transitions under the constraint of specified accuracy levels. According to the obtained results, a promising waveguide taper concept will finally be presented.
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Voropaiev, G. A., and O. O. Baskova. "SOME FEATURES OF A LAMINAR FLOW STABILITY LOSS IN A PIPE." Journal of Numerical and Applied Mathematics, no. 1 (135) (2021): 59–65. http://dx.doi.org/10.17721/2706-9699.2021.1.07.
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Despite the seeming simplicity of the steady flow in a pipe of constant radius, the question of the cause and process of the transition remains debatable. Especially since the necessary condition for the stability loss of parabolic profile is not satisfied, and the linear theory of hydrodynamic stability for an axisymmetric Poiseuille flow does not give growing axisymmetric eigen solutions for any Reynolds numbers, since the terms characterizing the interaction of disturbances with the initial velocity profile drop out in the linearized equations of momentum conservation. The report presents the results of the study of stages of convective stability loss for the flow at the initial section of the pipe depending on the variable parameters based on the numerical solution of the three-dimensional system of unsteady Navier-Stokes equations and the equation energy transfer. The variable parameters in this study were: Reynolds number, magnitude and gradient sign of the dynamic viscosity coefficient arising in nonisothermal flows. An analogy of the arising secondary axisymmetric large-scale toroidal vortex structures in the near-wall region to Tollmien-Schlichting waves in the region of the transition of the laminar boundary layer on the plate is shown. The subsequent loss of axisymmetry and stability of these torus-like vortex structures is analyzed, which leads to the formation of fairly regular longitudinal vortex structures downstream, the nonlinear interaction of which leads to chaotization of the flow. The lengths of these sections are determined depending on the Reynolds number, the magnitude and sign of the gradient of the dynamic viscosity coefficient.
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MUDDE, ROBERT F., and TAKAYUKI SAITO. "Hydrodynamical similarities between bubble column and bubbly pipe flow." Journal of Fluid Mechanics 437 (June 22, 2001): 203–28. http://dx.doi.org/10.1017/s0022112001004335.
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The hydrodynamical similarities between the bubbly flow in a bubble column and in a pipe with vertical upward liquid flow are investigated. The system concerns air/water bubbly flow in a vertical cylinder of 14.9 cm inner diameter. Measurements of the radial distribution of the liquid velocity, gas fraction and the bubble velocity and size are performed using laser Doppler anemometry for the liquid velocity and a four-point optical fibre probe for the gas fraction, bubble velocity and size. The averaged gas fraction was 5.2% for the bubble column (with a superficial liquid velocity of zero) and 5.5% for the bubbly pipe flow at a superficial liquid velocity of 0.175 m s−1. From a hydrodynamical point of view, the two modes of operation are very similar. It is found that in many respects the bubbly pipe flow is the superposition of the flow in the bubble column mode and single-phase flow at the same superficial liquid velocity.The radial gas fraction profiles are the same and the velocity profiles differ only by a constant offset: the superficial liquid velocity. This means that the well-known large-scale liquid circulation (in a time-averaged sense) of the bubble column is also present in the bubbly pipe flow. For the turbulence intensities it is found that the bubbly pipe flow is like the superposition of the bubble column and the single-phase flow at the superficial liquid velocity of the pipe flow, the former being at least an order of magnitude higher than the latter. The large vortical structures that have been found in the bubble columns are also present in the bubbly pipe flow case, partly explaining the much higher ‘turbulence’ levels observed.
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Okudan, Gorkem, Chenxi Xu, Hrishikesh Danawe, Serife Tol, and Didem Ozevin. "Controlling the thickness dependence of torsional wave mode in pipe-like structures with the gradient-index phononic crystal lens." Ultrasonics 124 (August 2022): 106728. http://dx.doi.org/10.1016/j.ultras.2022.106728.
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Yu, Feng, Jing Yu He, and Zhong Miao Zhang. "Current Use of Prestressed Concrete Pipe Piles Founded in Silty Geomaterials." Advanced Materials Research 168-170 (December 2010): 116–20. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.116.
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Prestressed concrete pipe piles have been increasingly used as deep foundation structures for decades. Despite the availability of a limited number of well-instrumented load test results, pile designers would like to know the general performance of such piles in case of lacking adequate experience. An attempt is made in this study to establish a database composed of more than one thousand of pile tests. All piles are founded in silty soil that is one of the competent bearing geomaterials. Short and medium-length piles with slenderness ratios ranging from 20 to 80 are most widely used. The capacity of pile increases with increasing the pile slenderness ratio until a limiting value is achieved. Use of very long piles to reduce settlement is unfavorable and the rebound rates for piles with various lengths are similar. An independent case study is also conducted to witness the success of employing the empiricism-based analyses in the preliminary design of concrete pipe piles.
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Piotrowski, B., T. Ben Zineb, E. Patoor, and A. Eberhardt. "A finite element–based numerical tool for Ni47Ti44Nb9 SMA structures design: Application to tightening rings." Journal of Intelligent Material Systems and Structures 23, no. 2 (December 19, 2011): 141–53. http://dx.doi.org/10.1177/1045389x11429852.
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This paper deals with the design of Ni47Ti44Nb9 shape memory alloy (SMA) tightening components. The tightening of an SMA ring on an elastic pipe is analyzed using the finite element code ABAQUS® and a UMAT subroutine developed by the authors to model the specific behavior of Ni47Ti44Nb9 SMA. Main features of the thermomechanical model implemented in this UMAT routine are briefly recalled. Numerical predictions are validated using experimental tightening pressures obtained on a test bed developed in this work. The validation strategy is documented and the results for different ring thicknesses are presented. This finite element tool is then applied to a parametric study of the influence of ridges on the tightening pressure. Eventually, geometrical defects like out of roundness are considered.
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Kamble, Vishal, S. D. Bharti, M. K. Shrimali, and T. K. Datta. "3D-Seismic Response Analysis of the Secondary Piping System in Building Under Bi-Directional Earthquake." Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, no. 1 (December 19, 2022): 821–27. http://dx.doi.org/10.38208/acp.v1.589.
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The secondary piping systems running along the height of buildings are subjected to significant stresses and accelerations due to the earthquake. Extensive research on the seismic response of primary and secondary systems has been carried out in the past. State of the art review papers on the subjects summarizes those researches. Although the response of the secondary piping system running along with the height of the primary structure like the building has been studied before, the stresses and accelerations developed in the piping system developed due to the bi-directional earthquake are not widely studied. In this paper, a six storied building with a secondary system taken as a pipe running from 1st to 6th story on one side of the building is taken as an illustrative example. A 3-D model of the primary and secondary system is analyzed for bi-directional earthquakes. Considering the full interaction between the primary and secondary structures, the non- linear time history analysis is carried out in SAP 2000 to obtain different response quantities of interest for a PGA level 0.3g with the major to minor ground motion ratio taken as 1:2/3. Response quantities of interest include the maximum accelerations, maximum displacements, and maximum stresses developed at critical sections of the pipe. Also, the floor response spectra are obtained. Results of the numerical study indicate that significant accelerations and stresses are induced in the pipe for a PGA level of 0.3g; the absolute accelerations at the pipe supports vary significantly leading to the generation of large stresses in the pipe.
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Sau, Amalendu. "Topological growth of multi-deck vortex structures above an elevated cross jet." Physics of Fluids 34, no. 7 (July 2022): 074114. http://dx.doi.org/10.1063/5.0098735.
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The present numerical study provides a detailed topology-based understanding of the three-dimensional vortical flow interaction process for an elevated square cross jet of low-to-moderate velocity ratio (0.25 [Formula: see text] 4.0). For [Formula: see text] 0.5, a steady inner-vortex ( Iv) formed in the jet pipe owing to the leading-edge jet shear layer roll up as a spiral node. The kinematics of the limiting streamlines and separation-attachment patterns along the jet shear layer confirm the presence of the Iv. For 0.5 < [Formula: see text] 1.2, the Iv partly escapes, as its front side remains attached to the pipe hole and the azimuthally extended lee side moved out in a tilted fashion. Moreover, the continuous vortex shedding from the stack created a dominant von Karman-like street that grew along the lower side of the jet wake. Distinctly for R = 4, the intruded convective crossflow pulled up the spiral front node/ Iv out of the pipe, which also shifted the onset of the Kelvin–Helmholtz instability upward. Significantly, the pulled-up node/ Iv facilitated the above-orifice anti-kidney vortical evolution of the issuing jet shear layer. For the first time, the study displays the triple-deck growth of the kidney and anti-kidney vortices above an elevated square cross jet for 2.5 ≤ R ≤ 4.0 and 1000 [Formula: see text] Re [Formula: see text] 2000. For 0.5 ≤ R ≤ 1.2, the double-decked kidney vortices involving the primary and the secondary pairs grew above the central jet column. However, the stronger primary pair fast entrained the secondary one close to the orifice edge. With R [Formula: see text] 2.5, the lateral jet shear layer experienced an unexpected windward concave warping and restructured to evolve as the anti-kidney third-deck situated above the mid-deck primary kidney vortices. The topological shear layer folding and created kidney/anti-kidney vortices above the elevated square cross jet, for 0.25 [Formula: see text] 4.0, appear consistent with the past measurements for a high aspect ratio elliptic flush jet. The anti-kidney vortical growth though was not detected above a square flush jet. The dominating above-orifice topological node in the high-pressure area ensured the anti-kidney vortical growth via the generated local pressure-gradient induced flow acceleration.
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Aijazi, Ahmad K., Laurent Malaterre, Laurent Trassoudaine, Thierry Chateau, and Paul Checchin. "Automatic Detection and Modeling of Underground Pipes Using a Portable 3D LiDAR System." Sensors 19, no. 24 (December 4, 2019): 5345. http://dx.doi.org/10.3390/s19245345.
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Automatic and accurate mapping and modeling of underground infrastructure has become indispensable for several important tasks ranging from urban planning and construction to safety and hazard mitigation. However, this offers several technical and operational challenges. The aim of this work is to develop a portable automated mapping solution for the 3D mapping and modeling of underground pipe networks during renovation and installation work when the infrastructure is being laid down in open trenches. The system is used to scan the trench and then the 3D scans obtained from the system are registered together to form a 3D point cloud of the trench containing the pipe network using a modified global ICP (iterative closest point) method. In the 3D point cloud, pipe-like structures are segmented using fuzzy C-means clustering and then modeled using a nested MSAC (M-estimator SAmpling Consensus) algorithm. The proposed method is evaluated on real data pertaining to three different sites, containing several different types of pipes. We report an overall registration error of less than 7 % , an overall segmentation accuracy of 85 % and an overall modeling error of less than 5 % . The evaluated results not only demonstrate the efficacy but also the suitability of the proposed solution.
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Semerak, M., D. Kharyshyn, N. Ferents, and T. Berezhanskyi. "INVESTIGATION OF THE EFFICIENCY OF THE STEEL TUBE CONFINEMENT CONCRETE PILLARS PROTECTION BY FIRE-RETARDANT MATERIALS." Fire Safety, no. 33 (December 31, 2018): 95–100. http://dx.doi.org/10.32447/20786662.33.2018.13.
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Currently, in Ukraine and abroad for the construction of high-rise buildings and structures using pipe-like structures. Wide application of pipe concrete columns is due to their high carrying capacity at relatively smaller overall dimensions due to the blocking of cracking in concrete by a steel clasp. The advantages of concrete columns should include more simplified conditions of technology of manufacturing and installation on their basis of bearing structures of floor covering.
Piping constructions consist of steel shells and concrete core. Since the steel pipe mainly provides the bearing capacity of the concrete column, its failure or reduction of stiffness, which is characteristic of the fire under the influence of its thermal factors, leads to destruction. Investigation of fire resistance of concrete structures, which are not protected by flame retardant coatings, showed that a steel clasp during a fire after 15 minutes is heated to a critical temperature of 500 ° C.The use of flame retardant coatings is an effective method of fire protection of concrete constructions, which prevents the rapid heating of steel welds and provides a normalized fire resistance limit for such structures. In this work, studies were carried out on the effectiveness of fire protection of concrete columns with different types of fire-retardant materials - mineral wool slabs, special flame retardants and flame-retardant coatings. For fire protection mineral wool materials were used ROCKWOOL plates of the series "Conlit SL150". Mineral wool plates "Conlit SL 150" consist of fibers of rocks of a basalt group, they can withstand, without melting, temperature more than 1000 ° С. The silica-based adhesive "Conlit Glue" can withstand temperatures above 900 ° C, has good adhesion when bonding Conlit SL 150 mineral wool slabs with protective structures. From the second type of fire-retardant materials, the fire-proof composition "Naktresk" was chosen on the basis of gypsum. The coating is formed in the process due to hardening of the mixture on protected surfaces. The third type of flame retardant materials is the flame-retardant intumessent coating "Pyro-Safe Flammoplast SP-A2".It has been established that with the use of fire protection systems on the basis of mineral wool plates "Conlit SL150" and fire retardant "Nutresc", the fire resistance class of reinforced concrete columns increases from R 15 to R 180. The fire protection system on the basis of the painted paint "Pyro-Safe Flammoplast SP-A2" »Increases fire resistance from R 15 to R 75
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Kita, Jaroslaw, Annica Brandenburg, and Ralf Moos. "Application of Cylindrical Pipe-Type LTCC Substrates as a Platform for Multi-Array Gas Sensors." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2013, CICMT (September 1, 2013): 000288–92. http://dx.doi.org/10.4071/cicmt-tha46.
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Thick-film technology-based gas sensors have been known for many years. On a ceramic substrate, a thick-film heater, electrodes, and a gas sensitive layer are deposited. Due to the ease of layer deposition, such structures are usually manufactured as planar ones. However, recently-suggested cylindrical pipe-type substrates made in LTCC technology offer unique inherent advantages for gas sensor technology, like a uniform temperature profile along the gas sensitive layer or a reduction of the distortion of the gas flow in the pipe. As shown in our previous study, cylindrical LTCC substrates with inner electrodes and integrated heaters may be very promising in the field of high-temperature gas sensors. In this paper, we continue our work on cylindrically shaped LTCC sensor substrates, with special focus on the construction of a platform with multiple heater/electrodes couples for multi-array gas sensors. For such multi-sensor structures, decoupling of the heat sources is the most important platform feature. Therefore, a cylindrical substrate with integrated heaters was FEM-modeled and optimized in the first stage. Subsequently, tubes with three integrated heaters were prepared. In this paper, it is discussed how reduced thermal masses can be obtained by thinner tube walls or by the integration of laser-patterned cavities and how different integrated heat sources can be decoupled.
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Guy, Pluvinage, Toth Laszlo, and Capelle Julien. "Effects of Hydrogen Addition on Design, Maintenance and Surveillance of Gas Networks." Processes 9, no. 7 (July 15, 2021): 1219. http://dx.doi.org/10.3390/pr9071219.
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Hydrogen, when is blended with natural gas over time, degrades the materials used for pipe transport. Degradation is dependent on the proportion of hydrogen added to the natural gas. The assessment is made according to hydrogen permeation, risk to the integrity of structures, adaptation of surveillance and maintenance of equipment. The paper gives a survey of HE and its consequence on the design and maintenance. It is presented in a logical sequence: the design before use; the hydrogen embrittlement (HE) effects on Maximum Allowable Operating Pressure (MAOP); maintenance and surveillance during use of smooth and damaged pipes; and, particularly, for crack-like defects, corrosion defects and dents.
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Engel, Maximilian, Christian Kuehn, and Björn de Rijk. "A traveling wave bifurcation analysis of turbulent pipe flow." Nonlinearity 35, no. 11 (October 13, 2022): 5903–37. http://dx.doi.org/10.1088/1361-6544/ac9504.
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Abstract Using various techniques from dynamical systems theory, we rigorously study an experimentally validated model by [Barkley et al 2015 Nature 526 550–3], which describes the rise of turbulent pipe flow via a PDE system of reduced complexity. The fast evolution of turbulence is governed by reaction-diffusion dynamics coupled to the centerline velocity, which evolves with advection of Burgers’ type and a slow relaminarization term. Applying to this model a spatial dynamics ansatz and geometric singular perturbation theory, we prove the existence of a heteroclinic loop between a turbulent and a laminar steady state and establish a cascade of bifurcations of various traveling waves mediating the transition to turbulence. The most complicated behaviour can be found in an intermediate Reynolds number regime, where the traveling waves exhibit arbitrarily long periodic-like dynamics indicating the onset of chaos. Our analysis provides a systematic mathematical approach to identifying the transition to spatio–temporal turbulent structures that may also be applicable to other models arising in fluid dynamics.
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Magisano, Domenico, Marisa Mastroianni, Leonardo Leonetti, Antonio Madeo, Giovanni Garcea, Gianfranco Gagliardi, Alessandro Casavola, et al. "A Finite Element Model for Monitoring the Displacement of Pipelines in Landslide Regions by Discrete FBG Strain Sensors." Applied Sciences 12, no. 15 (July 26, 2022): 7510. http://dx.doi.org/10.3390/app12157510.
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This study investigates a system for monitoring displacements of underground pipelines in landslide-prone regions. This information is an important alarm indicator, not only to prevent the failure of the line itself but also to mitigate the direct consequences of landslides on buildings and infrastructures in the affected area. Specifically, a numerical processing tool coupled with a data acquisition system is proposed. The starting point is the measurement of axial strain at three points of discrete sections of the pipeline by Fiber Bragg grating sensors, used to approximate the trend of mean axial strain and bending curvatures along the pipe axis. A finite element analysis based on a 3D geometrically exact beam model is developed for computing the deformed configuration corresponding to the input strain field. After assigning the boundary conditions, a mixed iterative scheme is used for a quick solution to the nonlinear problem. Firstly, the tool is validated theoretically with benchmarks on beam-like structures undergoing large deflections. Then, experimental results are produced on a monitored pipe buried in a wedge of land subject to an artificial slide. The overall sensor-modeling system, with zero displacements far from the landslide as a boundary condition, provides a satisfactory displacement trend with a mean error of about 18% with just three effective monitored sections in the affected pipe stretch of 18 m. The acquisition and processing tool is implemented in a web application as a real-time alarm system.
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Jinescu, Valeriu V., Angela Chelu, Gheorghe Zecheru, Alexandru Pupazescu, Teodor Sima, and Gheorghe Draghici. "The Influence of Loads Superposition, Deterioration Due to Cracks and Residual Stresses on the Strength of Tubular Junction." Revista de Chimie 68, no. 6 (July 15, 2017): 1267–73. http://dx.doi.org/10.37358/rc.17.6.5655.
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In the paper the interaction of several loads like pressure, axial force, bending moment and torsional moment are analyzed, taking into account the deterioration due to cracks and the influence of residual stresses. A nonlinear, power law, of structure material is considered. General relationships for total participation of specific energies introduced in the structure by the loads, as well as for the critical participation have been proposed. On these bases: - a new strength calculation methods was developed; � strength of tubular cracked structures and of cracked tubular junction subjected to combined loading and strength were analyzed. Relationships for critical state have been proposed, based on dimensionless variables. These theoretical results fit with experimental date reported in literature. On the other side stress concentration coefficients were defined. Our one experiments onto a model of a pipe with two opposite nozzles have been achieved. Near one of the nozzles is a crack on the run pipe. Trough the experiments the state of stress have been obtained near the tubular junction, near the tip of the crack and far from the stress concentration points. On this basis the stress concentration coefficients were calculated.
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Kim, Kiyoung, and Haecheon Choi. "Direct numerical simulation of a turbulent core-annular flow with water-lubricated high viscosity oil in a vertical pipe." Journal of Fluid Mechanics 849 (June 20, 2018): 419–47. http://dx.doi.org/10.1017/jfm.2018.408.
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The characteristics of a turbulent core-annular flow with water-lubricated high viscosity oil in a vertical pipe are investigated using direct numerical simulation, in conjunction with a level-set method to track the phase interface between oil and water. At a given mean wall friction ($Re_{\unicode[STIX]{x1D70F}}=u_{\unicode[STIX]{x1D70F}}R/\unicode[STIX]{x1D708}_{w}=720$, where $u_{\unicode[STIX]{x1D70F}}$ is the friction velocity, $R$ is the pipe radius and $\unicode[STIX]{x1D708}_{w}$ is the kinematic viscosity of water), the total volume flow rate of a core-annular flow is similar to that of a turbulent single-phase pipe flow of water, indicating that water lubrication is an effective tool to transport high viscosity oil in a pipe. The high viscosity oil flow in the core region is almost a plug flow due to its high viscosity, and the water flow in the annular region is turbulent except for the case of large oil volume fraction (e.g. 0.91 in the present study). With decreasing oil volume fraction, the mean velocity profile in the annulus becomes more like that of turbulent pipe flow, but the streamwise evolution of vortical structures is obstructed by the phase interface wave. In a reference frame moving with the core velocity, water is observed to be trapped inside the wave valley in the annulus, and only a small amount of water runs through the wave crest. The phase interface of the core-annular flow consists of different streamwise and azimuthal wavenumber components for different oil holdups. The azimuthal wavenumber spectra of the phase interface amplitude have largest power at the smallest wavenumber whose corresponding wavelength is the pipe circumference, while the streamwise wavenumber having the largest power decreases with decreasing oil volume fraction. The overall convection velocity of the phase interface is slightly lower than the core velocity. Finally, we suggest a predictive oil holdup model by defining the displacement thickness in the annulus and considering the boundary layer characteristics of water flow. This model predicts the variation of the oil holdup with the superficial velocity ratio very well.
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Seleem, Muhammad, Fatima Alam Khan, and Aleena Zaman. "Wh-Movement Pattern in the Spoken Discourse of Teachers: A Syntactic Analysis." Global Social Sciences Review III, no. II (June 30, 2018): 400–420. http://dx.doi.org/10.31703/gssr.2018(iii-ii).23.
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This study investigates the syntactic structures of spoken discourse of teachers in academic discourse. The knowledge of syntactic structure of a language helps in understanding the spoken discourse. So, the study identifies the wh-Movement in the syntactic structures of teachers in English classroom sessions. The data was collected from two universities of Federal government, Pakistan. The one was Air University Islamabad and the second was National University of Modern Languages Islamabad. The data was collected through the recording tool where the English classroom sessions of the teachers were audio-recorded and transcribed. The analysis of data was quantitative and qualitative in nature. The frequency of wh-movement in the structures of recorded English spoken data was analysed quantitatively. In qualitative analyses, the transcribed data was analysed syntactically, keeping in view minimalist perspective, with the help of parsing rules and figures. The analyzed data shows that the teachers at undergraduate level use language where wh-movement is employed in syntactic structure of English used in classroom sessions. They move whexpression into other slots like internal merge and pied-pipe. However, the minimalist parametric unit, wh-movement, was found in the sentence structures of the teachers in the delivery of classroom sessions. So, the minimal pairs of sentence structure impacts different level of language.
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Toklu, Yusuf Cengiz, Gebrail Bekdaş, Melda Yücel, Sinan Melih Nigdeli, Aylin Ece Kayabekir, Sanghun Kim, and Zong Woo Geem. "Total Potential Optimization Using Metaheuristic Algorithms for Solving Nonlinear Plane Strain Systems." Applied Sciences 11, no. 7 (April 3, 2021): 3220. http://dx.doi.org/10.3390/app11073220.
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Total Potential Optimization using Metaheuristic Algorithms (TPO/MA) is an alternative tool for the analysis of structures. It is shown that this emerging method is advantageous in solving nonlinear problems like trusses, tensegrity structures, cable networks, and plane stress systems. In the present study, TPO/MA, which does not need any specific implementation for nonlinearity, is demonstrated to be successfully applied to the analysis of plane strain structures. A numerical investigation is performed using nine different metaheuristic algorithms and an adaptive harmony search in linear analysis of a structural mechanics problem having 8 free nodes defined as design variables in the minimization problem of total potential energy. For nonlinear stress-strain relation cases, two structural mechanics problems, one being a thick-walled pipe and the other being a cantilever retaining wall, are analyzed by employing adaptive harmony search, which was found to be the best one in linear analyses. The nonlinear stress-strain relations considered in these analyses are hypothetical ones due to the lack of any such relationship in the literature. The results have shown that TPO/MA can solve nonlinear plane strain problems that can be encountered as engineering problems in structural mechanics.
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Machado, M., G. Marcellino, J. D. Salazar, D. J. Regner, P. Buschinelli, J. M. Santos, C. Marinho, and T. C. Pinto. "RPA POSITIONING ERROR INFLUENCE ON CLOSE RANGE PHOTOGRAMMETRY FOR INDUSTRIAL INSPECTION." International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B2-2021 (June 28, 2021): 541–48. http://dx.doi.org/10.5194/isprs-archives-xliii-b2-2021-541-2021.
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Abstract. In oil and gas offshore platforms, special pipelines as flexible risers make the connection between the ocean floor structures and the platform in extreme environmental and operational conditions. Periodic inspections are necessary to assess their integrity. As industrial climbing for inspection is expensive, extremely dangerous and time consuming, qualitative visual inspection with Remotely Piloted Aircraft System (RPAS), also known as drones, are being successfully applied for remote inspection of offshore flares and risers in a much safer, quicker, and cheaper way. These experiences motivate the 3D photogrammetric inspection of risers using RPAS, considering restrictions like layout of the inspected structures and surroundings and inability to prepare the scene. In this paper, taking advantage of the position information provided by the RPAS, the reconstruction and scale of the test scene were made using only GNSS data, GNSS and scale bars, RTK, and RTK and scale bars. Calibrated artifacts were used to evaluate the results and they include a PVC pipe with artificial defects simulating a riser, a pyramidal pattern with four spheres, and scale bars. The results showed that, as expected, the worst results are for GNSS data with error standard deviations of 0.35 mm compared with 0.20 mm or less for other options. For the sphere’s artifact, relative maximum sphere spacing errors are 9.3% for GNSS, 1.9% for RTK and 0.26% using scale bars. In any case it was possible to identify the defects in the pipe with good quality and with much more detail compared with a climbing inspection.
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Zhang, Xiantao, and Wei Liu. "The effect of pipeline layout parameters on mode and dynamic stress of “airframe-clamps-pipeline” structure." Multidiscipline Modeling in Materials and Structures 16, no. 2 (October 15, 2019): 373–89. http://dx.doi.org/10.1108/mmms-05-2019-0106.
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Purpose In the coupling of aircraft pipeline structures, current research works mainly focus on fluid-solid coupling effects or a single part of structure vibration like a pipeline. Because of the clamp, the pipe vibration caused by fluid pulsation was transmitted to the body, and the body vibration was also transmitted to the pipe structure. Thus, the relationship between the airframe and the pipeline system cannot be separated, and the influence of airframe needs to be considered when coupling structure under vibration. The paper aims to discuss these issues. Design/methodology/approach This paper aims to investigate the influence of pipeline layouts on airframe-clamps-pipeline (ACP) structure’s dynamic response by experiment and simulation method. First, ACP structures are established including three parts. The natural frequencies and mode shapes are obtained by hammering experiment. The mode results are in agreement with numerical simulation. By using electromagnetic vibration shaker, extinction is applied on ACP structure, and then the dynamic responses of structure can be obtained by test equipments. The influence principle of pipeline layouts is obtained by dynamic response analysis. The present study provides a method for pipeline layout design in aerospace engineering. Findings Under the ACP’s first-order resonance frequency excitation, the maximum stress increases when the Z-shaped pipeline bending position changes from 1/2 to 1/5. The opposite way occurs under the only pipeline resonance frequency excitation. The stress amplitudes near both sides (inner and outer) of the clamp on the plate surface change with the excitation frequency. Under the ACP’s first-order resonance frequency excitation, the outer side stress is larger than the inner side stress, but under the only pipeline resonance frequency excitation, the inner side stress is larger than the outer side stress. Originality/value The study of the effect of pipeline layout parameters on ACP structure provides a method for pipeline layout design in aerospace engineering.
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Hagen, Christina, Pragathi Gurumurthy, and Thorsten M. Buzug. "Effects of replacing the nasal cavity with a simple pipe like structure in CFD simulations of the airflow within the upper airways of OSA patients with patient individual flow rates." Current Directions in Biomedical Engineering 3, no. 2 (September 7, 2017): 795–98. http://dx.doi.org/10.1515/cdbme-2017-0168.
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AbstractOSA is characterized by repetitive collapses of the upper airways during sleep. Computational fluid dynamics can be used to investigate the abnormal pressure distribution in the patient’s airways. The computational costs and model reconstruction effort can be reduced by focusing the simulations on the pharynx and replacing the nasal cavity by a simple pipe structure. In this work, the effects of the mentioned replacement on the simulated flow are evaluated. Airflow simulations using the k-ω turbulence model are performed in the anatomically correct airway of a patient having a high difference in the inspiratory volume flow rates of both nostrils, as well as in a model with replaced nasal cavity by a simple pipe structure. The simulated pressure distributions of both models are in very good agreement indicating the acceptability of replacing the nasal cavity by simple pipe structures in in-silico airflow analyses of OSA patients.
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Hu, Fuwen, and Tian Li. "An Origami Flexiball-Inspired Metamaterial Actuator and Its In-Pipe Robot Prototype." Actuators 10, no. 4 (March 26, 2021): 67. http://dx.doi.org/10.3390/act10040067.
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Usually, polyhedra are viewed as the underlying constructive cells of packing or tiling in many disciplines, including crystallography, protein folding, viruses structure, building architecture, etc. Here, inspired by the flexible origami polyhedra (commonly called origami flexiballs), we initially probe into their intrinsic metamaterial properties and robotized methods from fabrication to actuation. Firstly, the topology, geometries and elastic energies of shape shifting are analyzed for the three kinds of origami flexiballs with extruded outward rhombic faces. Provably, they meet the definitions of reconfigurable and transformable metamaterials with switchable stiffness and multiple degrees of freedom. Secondly, a new type of soft actuator with rhombic deformations is successfully put forward, different from soft bionic deformations like elongating, contracting, bending, twisting, spiraling, etc. Further, we redesign and fabricate the three-dimensional (3D) printable structures of origami flexiballs considering their 3D printability and foldability, and magnetically actuated them through the attachment of magnetoactive elastomer. Lastly, a fully soft in-pipe robot prototype is presented using the origami flexiball as an applicable attempt. Experimental work clearly suggests that the presented origami flexiball robot has good adaptability to various pipe sizes, and also can be easily expanded to different scales, or reconfigured into more complex metastructures by assembly. In conclusion, this research provides a newly interesting and illuminating member for the emerging families of mechanical metamaterials, soft actuators and soft robots.
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Guan, Yan Fang, Ming Gang Shen, and Li Li Han. "Simulations and Experiment Analysis of a Piezoelectric Micropump." Applied Mechanics and Materials 229-231 (November 2012): 1688–92. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.1688.
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The application of micropump in microanalytical reagent is widely. In this paper a piezoelectric micropump model that looks like a sandwitch has been put forward. The main structures of the micropump include inlet and outlet pipe, silicon substrate pump body, piezoelectric transducer. In order to find the excellent driving performance, the modals and piezoelectric-stress coupling analysis of the piezoelectric transducer has been carried out with finite element analysis methods. The result proves that the optimal working condition of the micropump is the 1st mode. Finally the micropump model has been fabricated with silicon deep reactive ion etching and UV irreversible irradiation. Through experiment the flow rate and pressure of the micropump reach the maximum in first-order modal that is less than 1000 Hz, and this is accord with the modal analysis.
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He, Zhen, and Tucker A. Patterson. "A Potential Role for the Existence of Pericytes in the Neurovascular Unit of the Sexually Dimorphic Nucleus of the Rat Preoptic Area to Control Blood-Brain Barrier Function." Current Neurovascular Research 16, no. 3 (September 17, 2019): 194–201. http://dx.doi.org/10.2174/1567202616666190627120135.
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Background: The present study aimed at determining pericytes, a missing component in the previously proposed living neurovascular unit (NVU) of the sexually dimorphic nucleus of the preoptic area (SDN-POA) in rats. Materials and Mehods: Calbindin D28K-immunoreactivities (CB28-irs) were used to delineate the SDN-POA in which CD13-immunoreactivities (CD13-irs) or alpha-smooth muscle actinimmunoreactivities (αSMA-irs), two pericyte biomarkers serving the indexes of pericytes, were tagged using two adjacent brain sections (90-micron intervals). In addition, the nestinimmunoreactive (nestin-ir) cells in the SDN-POA were counted as pericytes referring to additional standards: location and nucleic and cellular morphology. Male SDN-POA volume (5.0±0.3x10-3 mm3) was significantly larger than the female (1.7±0.3x10-3 mm3). Within the SDN-POA, the CD13-irs were characterized as dots, densely packed and net-like in distribution, while the αSMAirs, excluding pipe-like or circular structures, appeared as short rod-like structures that were sparsely distributed. Results: The immunoreactive counts of alpha-smooth muscle actin were 353±57/mm2 in males and 124±46/mm2 in females (p<0.05). On the other hand, densities of the dot-like CD13-irs were similar between males (4009±301/mm2) and females (4018±414/ mm2). There was no difference between the male and the female in the nestin-ir pericyte count in the SDN-POA. Conclusion: In conclusion, the present study adds new information concerning pericytes to the living NVU of the SDN-POA. There is a difference of sex in the count of the αSMA-irs in the living NVU of the SDN-POA. However, why such a difference exists warrants further investigations.
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Lee, Jae Hwa, Hyung Jin Sung, and Ronald J. Adrian. "Space–time formation of very-large-scale motions in turbulent pipe flow." Journal of Fluid Mechanics 881 (October 25, 2019): 1010–47. http://dx.doi.org/10.1017/jfm.2019.786.
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We examine the origin of very-large-scale motions (VLSMs) in fully developed turbulent pipe flow at friction Reynolds number, $\mathit{Re}_{\unicode[STIX]{x1D70F}}=934$, using data from a direct numerical simulation. The VLSMs and the packet-like large-scale motions (LSMs) found in this study are very similar to those found in earlier studies. Three-dimensional time-evolving instantaneous fields show that one component of the process leading to the large streamwise length of VLSMs is the concatenation of adjacent streamwise LSMs caused by the continuous elongation of LSMs due to the strain component of the mean shear. Spatial organization patterns of the VLSMs and LSMs and their properties are studied by separating auto-correlation of the streamwise velocity fluctuations into the components of the VLSM and the LSM defined by low-pass/high-pass filtering in the streamwise direction. The structures of the two-point spatial correlations of the streamwise velocity component of the VLSMs and the LSMs in the streamwise-azimuthal plane are characterized by multiple maxima and complex patterns that beg explanation in terms of patterned coherent arrangements of the LSMs. Using proper orthogonal decomposition (POD), it is found that the X-shape correlation pattern of the VLSMs results from the superposition of very long helically inclined structures and streamwise-aligned structures. Further explanation of the patterns in the correlations of the VLSMs and LSMs is provided through the study of synthetically constructed arrangements of simple hairpin packet models of the LSM. Head-to-tail alignment of the model packets along streamwise and helical directions suggested by the eigenvalues of the POD creates a pair of long roll-cells centred above the logarithmic layer, and bracketing the LSMs. These roll-cells are pure kinematic consequences of the induction within the LSM packets, but they may also serve to organize smaller packets.
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Winters, Jeffrey. "The Nanoscale Frontier." Mechanical Engineering 138, no. 11 (November 1, 2016): 45–47. http://dx.doi.org/10.1115/1.2016-nov-3.
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This article presents an overview of various aspects of nanoscale technology. As opposed to the macroscale, where water molecules next to a pipe wall have zero velocity, in nanochannels, fluid molecules slip at the channel surface, experiencing an enhanced convective transport. Nanotechnology can also help us alter natural designs. Carbon nanotubes act like a reinforcement to give synthetic tissue the strength, stiffness, and viscoelastic performance of natural membranes. In order to store macroscopically significant amounts of energy, one needs to deform large numbers of carbon nanotubes. It is more challenging still to deform them in a way that maintains high-energy density of overall system. Micro- and nanoscale structures have given us capabilities to interact with cells and pathogens at their level as never before and helped us understand how they live, grow, multiply, differentiate, and die.
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Dwyer, H. A., A. Y. Cheer, T. Rutaganira, and N. Shacheraghi. "Calculation of Unsteady Flows in Curved Pipes." Journal of Fluids Engineering 123, no. 4 (June 6, 2001): 869–77. http://dx.doi.org/10.1115/1.1400748.
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Highly unsteady three-dimensional flows in curved pipes with significant variation of flow geometry and flow parameters are studied. Using improvements in computational efficiency, detailed knowledge concerning flow structures is obtained. The numerical solutions of the Navier-Stokes equations have been obtained with a variation of the projection method, and the numerical method was enhanced by new algorithms derived from the physics of the flow. These enhancements include a prediction of the flow unsteady pressure gradient based on fluid acceleration and global pressure field corrections based on mass flow. This new method yields an order of magnitude improvement in the calculation’s efficiency, allowing the study of complex flow problems. Numerical flow simulations for oscillating flow cycles show that the curved pipe flows have a significant inviscid-like nature at high values of the frequency parameter. The shape of the velocity profiles is strongly influenced by the frequency parameter, whereas the influence of variations on the pipe cross-sectional area is shown to be rather weak. For large values of the frequency parameter the flow history strongly influences the low mass flow part of the cycle leading to highly unusual velocity profiles. The wall shear stress is studied for all the flows calculated. Our results show that wall shear stress is sensitive to area constrictions, the frequency parameter, as well as the shape of the entrance profile.
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Venkateswaran, Swaminath, Damien Chablat, and Frédéric Boyer. "Numerical and Experimental Validation of the Prototype of A Bio-Inspired Piping Inspection Robot." Robotics 8, no. 2 (April 23, 2019): 32. http://dx.doi.org/10.3390/robotics8020032.
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Piping inspection robots are of greater importance for industries such as nuclear, chemical and sewage. Mechanisms having closed loop or tree-like structures can be employed in such pipelines owing to their adaptable structures. A bio-inspired caterpillar type piping inspection robot was developed at Laboratoire des Sciences du Numérique de Nantes (LS2N), France. Using DC motors and leg mechanisms, the robot accomplishes the locomotion of a caterpillar in six-steps. With the help of Coulomb’s law of dry friction, a static force model was written and the contact forces between legs of robot and pipeline walls were determined. The actuator forces of the DC motors were then estimated under static phases for horizontal and vertical orientations of the pipeline. Experiments were then conducted on the prototype where the peak results of static force analysis for a given pipe diameter were set as threshold limits to attain static phases inside a test pipeline. The real-time actuator forces were estimated in experiments for similar orientations of the pipeline of static force models and they were found to be higher when compared to the numerical model.
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Hesarkazzazi, Sina, Mohsen Hajibabaei, Julian David Reyes-Silva, Peter Krebs, and Robert Sitzenfrei. "Assessing Redundancy in Stormwater Structures Under Hydraulic Design." Water 12, no. 4 (April 1, 2020): 1003. http://dx.doi.org/10.3390/w12041003.
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As environmental change is happening at an unprecedented pace, a reliable and proper urban drainage design is required to alleviate the negative effects of unexpected extreme rainfall events occurring due to the natural and anthropogenic variations such as climate change and urbanization. Since structure/configuration of a stormwater network plays an imperative role in the design and hydraulic behavior of the system, the goal of this paper is to elaborate upon the significance of possessing redundancy (e.g., alternative flow paths as in loops) under simultaneous hydraulic design in stormwater pipe networks. In this work, an innovative approach based on complex network properties is introduced to systematically and successively reduce the number of loops and, therefore, the level of redundancy, from a given grid-like (street) network. A methodology based on hydrodynamic modelling is utilized to find the optimal design costs for all created structures while satisfying a number of hydraulic design constraints. As a general implication, when structures are subject to extreme precipitation events, the overall capability of looped configurations for discharging runoff more efficiently is higher compared to more branched ones. The reason is due to prevailing (additional) storage volume in the system and existing more alternative water flow paths in looped structures, as opposed to the branched ones in which only unique pathways for discharging peak runoff exist. However, the question arises where to best introduce extra paths in the network? By systematically addressing this question with complex network analysis, the influence of downstream loops was identified to be more significant than that of upstream loops. Findings, additionally, indicated that possessing loop and introducing extra capacity without determining appropriate additional pipes positions in the system (flow direction) can even exacerbate the efficiency of water discharge. Considering a reasonable and cost-effective budget, it would, therefore, be worthwhile to install loop-tree-integrated stormwater collection systems with additional pipes at specific locations, especially downstream, to boost the hydraulic reliability and minimize the damage imposed by the surface flooding upon the metropolitan area.
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Suzumori, Koichi, Akihiro Koga, Fumika Kondo, and Riyoko Haneda. "Integrated flexible microactuator systems." Robotica 14, no. 5 (September 1996): 493–98. http://dx.doi.org/10.1017/s0263574700019974.
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SUMMARYThe flexible microactuator (FMA) is a novel pneumaticrubber actuator developed for use in microrobots. Thispaper reports on integrated FMA systems to achievedistributed motion as occurs in intestinal villi, and withmulti-legged arthropods such as centipedes.For the purpose of miniaturization and integration of FMAs, the authors focussed on two technical issues: A new fabrication process based on stereo lithography and a new FMA design called a restraint beam FMA. Stereo lithography enables fabrication of micro-structures with rubber-like materials suitable for integrated FMAs. The restraint beam FMA makes it possible to fabricate FMAs from a single material, allowing stereo lithography to be used.As examples of integrated FMA systems, four prototypes are shown: a 5 × 5 FMA array, a 3 × 3 FMA array which has pneumatic circuits at its base, a pipe interior mobile robot, and an amusement system consisting of 30 FMAs, which demonstrates ball handling ability.
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Omoniyi, Sunday Samuel, Bashir Olufemi Odufuwa, and Festus Osarumwense Uzzi. "Residents’ Perception of Housing Quality Index for Dwellings’ Physical Characteristics in the Core Area of Ado-Ekiti, Nigeria." Jurnal Kejuruteraan 34, no. 2 (March 30, 2022): 223–30. http://dx.doi.org/10.17576/jkukm-2022-34(2)-05.
Full textAbstract:
This study examines residents’ perception of housing quality index for dwellings’ physical characteristics in the core area Ado-Ekiti, Nigeria, South-west Nigeria. A survey of 602 households randomly selected from the core area was done. The results of the study revealed that more than half of the respondents indicated that the present condition of the dwellings components like (roofs, walls, windows, floors, foundations and fascia boards) in the study area was in a very bad state. Subsequently, housing quality index (H.Q.I) for the entire sample was evaluated and the housing quality indexes results were found to be below average (fair) using a five-point Likert scale, starting from very bad (rated as 1), fair (rated as 3) to very good (rated as 5) to calculate the total weighted values of all rated attributes and means values of rated attributes in the study area. Surveyed results have shown significant deterioration in quality of dwellings components in the core area, due to age of buildings and lack of maintenance. The study concluded that there is an urgent need to replace the bad dwellings components, build new structures, provides basic amenities like electricity, pipe-borne water, roads/drainages and to refurbish the existing ones to ensure that the residents do not lack all these amenities.
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Heinlein, Sebastian, Peter Cawley, and Thomas Vogt. "Validation of a procedure for the evaluation of the performance of an installed structural health monitoring system." Structural Health Monitoring 18, no. 5-6 (September 12, 2018): 1557–68. http://dx.doi.org/10.1177/1475921718798567.
Full textAbstract:
Validation of the performance of guided wave structural health monitoring systems is vital if they are to be widely deployed; testing the damage detection ability of a system by introducing different types of damage at varying locations is very costly and cannot be performed on a system in operation. Estimating the damage detection ability of a system solely by numerical simulations is not possible as complex environmental effects cannot be accounted for. In this study, a methodology was tested and verified that uses finite element simulations to superimpose defect signals onto measurements collected from a defect-free structure. These signals are acquired from the structure of interest under varying environmental and operational conditions for an initial monitoring period. Measurements collected in a previous blind trial of an L-shaped pipe section, onto which a number of corrosion-like defects were introduced, were utilised during this investigation. The growth of three of these defects was replicated using finite element analysis and the simulated reflections were superimposed onto signals collected on the defect-free test pipe. The signal changes and limits of reliable detection predicted from the synthetic defect reflections superimposed on the measurements from the undamaged complex structure agreed well with the changes due to real damage measured on the same structure. This methodology is of great value for any structural health monitoring system as it allows for the minimum detectable defect size to be estimated for specific geometries and damage locations in a quick and efficient manner without the need for multiple test structures while accounting for environmental variations.