Journal articles on the topic 'Phase Angles'
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Zawawi, M. N. M., Z. M. Isa, M. H. Arshad, B. Ismail, and M. H. N. Talib. "Comparative Study of Multiphase 5-Level Cascaded H-Bridge Multilevel Inverter System." Journal of Physics: Conference Series 2312, no. 1 (August 1, 2022): 012062. http://dx.doi.org/10.1088/1742-6596/2312/1/012062.
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Abstract In terms of cost and structural design, the cascaded H-bridge multilevel inverter (CHBMLI) has a significant advantage over diode clamped and capacitor clamped multilevel inverters. The total harmonic distortion (THD) of a 5-level CHBMLI system for three different phases (single-phase, three-phase, and six-phase system) is studied and compared in this work. As switching angles play a role in lowering THD, the switching angles for a 5-level CHBMLI are evaluated using four specific switching angle methods in the initial section of this paper. In the simulation of single-phase system, these angles are being utilized. The angles with the lowest THD value are chosen for three-phase and six-phase system simulation. Based on the findings, the higher phase of 5-level CHBMLI is more efficient in decreasing harmonics.
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Khanamiri, Hamid Hosseinzade, Per Arne Slotte, and Carl Fredrik Berg. "Contact Angles in Two-Phase Flow Images." Transport in Porous Media 135, no. 3 (October 27, 2020): 535–53. http://dx.doi.org/10.1007/s11242-020-01485-y.
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AbstractIn this work, we calculate contact angles in X-ray tomography images of two-phase flow in order to investigate the wettability. Triangulated surfaces, generated using the images, are smoothed to calculate the contact angles. As expected, the angles have a spread rather than being a constant value. We attempt to shed light on sources of the spread by addressing the overlooked mesh corrections prior to smoothing, poorly resolved image features, cluster-based analysis, and local variations of contact angles. We verify the smoothing algorithm by analytical examples with known contact angle and curvature. According to the analytical cases, point-wise and average contact angles, average mean curvature and surface area converge to the analytical values with increased voxel grid resolution. Analytical examples show that these parameters can reliably be calculated for fluid–fluid surfaces composed of roughly 3000 vertices or more equivalent to 1000 pixel2. In an experimental image, by looking into individual interfaces and clusters, we show that contact angles are underestimated for wetting fluid clusters where the fluid–fluid surface is resolved with less than roughly 500 vertices. However, for the fluid–fluid surfaces with at least a few thousand vertices, the mean and standard deviation of angles converge to similar values. Further investigation of local variations of angles along three-phase lines for large clusters revealed that a source of angle variations is anomalies in the solid surface. However, in the places least influenced by such noise, we observed that angles tend to be larger when the line is convex and smaller when the line is concave. We believe this pattern may indicate the significance of line energy in the free energy of the two-phase flow systems.
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Mytsenko, I., and O. Roenko. "QUICK-ACTING, CONTROLLABLE PHASE SHIFTER FOR PHASE ANGLE ADJUSTMENT IN RADIO SIGNALS." RADIO PHYSICS AND RADIO ASTRONOMY 27, no. 3 (2022): 213–18. http://dx.doi.org/10.15407/rpra27.03.213.
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Subject and Purpose. The phase shifters intended for controlling the phase of radio signals are widely used in ultra-high frequency technology, communication systems, radar, and a variety of measuring and special-purpose radio equipment. Designers of phased array antennas face the need of providing for broad beam scanning angles and high antenna gains, which leads to the necessity of greatly increasing the number of array elements, each of which is to be controlled by a phase shifter. Therefore, the development and creation of quick-acting phase shifters is an urgent task. The purpose of this work is to develop high-speed, controllable phase shifters for performing phase angle adjustments and thus provide, at an acceptable cost, for desirable parameters of phased antenna arrays, frequency stabilizing systems of magnetrons, etc. Methods and Methodology. The functional diagram of the proposed quick-acting, controllable phase shifter has been analyzed mathematically and modelled numerically. Results. The controllable phase shifter can be successfully implemented through the use of two parallel-connected resonators at the input of a specific receiver. Analysis of the signal amplitude and phase at the output of the phase shifter in dependence on the values at the input confirms the possibility of adjusting the phase of the output signal over a wide range of angles. Conclusions. A design concept of quick-acting, controllable phase shifters for producing adjustable phase angles has been developed. The device can be employed in phased antenna arrays or frequency stabilizing systems as a means of improving their operation parameters and reducing their cost at that.
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de Parscau, J. "Relationship between phase velocities and polarization in transversely isotropic media." GEOPHYSICS 56, no. 10 (October 1991): 1578–83. http://dx.doi.org/10.1190/1.1442968.
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Most techniques used to estimate anisotropy from multiple‐source offset VSP data assume angles measured from particle motion as an incidence angle. However, the difference between P‐wave polarization and the propagation direction for an anisotropic medium can be higher than 8 degrees. This difference provides a nonnegligible error in the estimation of anisotropy parameters from phase velocities. An exact model, proposed to describe P‐ and SV‐phase velocity variations for a transversely isotropic medium (TIM), takes into account the polarization angles. This model is a function of two anisotropy parameters (η and τ), of the vertical P‐ and SV‐wave phase velocities and of the polarization angle γ. However, η and τ can be used to express the polarization angle equation in a much simpler way. To quantify the error in estimated anisotropy parameters due to the assumption that the polarization angle is equal to the incidence angle, I study five TIMs. Each medium has an anisotropy that is representative of those observed in seismic surveying. The anisotropy parameters are recovered by inverting the P‐ and SV‐wave phase velocities for different incidence angles, and these incidence angles are assumed to be equal to the corresponding polarization angles. The mean error in estimated parameters is about 10 percent. This error is about the same as the one that would be obtained for velocities with uncertainties in their measurements. Unfortunately, the inversion of phase velocities measured from a real multiple‐source offset VSP to estimate anisotropy parameters needs, for calculating the misfit function, to add both errors in velocities due to hypothesis for angles and errors in velocity measurements due to uncertainties in data. In this case an exact model eliminates errors due to the assumption for the model and provides a more accurate estimation of anisotropy parameters.
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Nakatake, Jun, Koji Totoribe, Hideki Arakawa, and Etsuo Chosa. "Exploring whole-body kinematics when eating real foods with the dominant hand in healthy adults." PLOS ONE 16, no. 10 (October 28, 2021): e0259184. http://dx.doi.org/10.1371/journal.pone.0259184.
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Despite the importance of eating movements to the rehabilitation of neurological patients, information regarding the normal kinematics of eating in a realistic setting is limited. We aimed to quantify whole-body three-dimensional kinematics among healthy individuals by assessing movement patterns in defined phases while eating real food with the dominant hand in a seated position. Our cross-sectional study included 45 healthy, right-hand dominant individuals with a mean age of 27.3 ± 5.1 years. Whole-body kinematics (joint angles of the upper limb, hip, neck, and trunk) were captured using an inertial sensor motion system. The eating motion was divided into four phases for analysis: reaching, spooning, transport, and mouth. The mean joint angles were compared among the phases with Friedman’s analysis of variance. The maximum angles through all eating phases were 129.0° of elbow flexion, 32.4° of wrist extension, 50.4° of hip flexion, 6.8° of hip abduction, and 0.2° of hip rotation. The mean shoulder, elbow, and hip joint flexion angles were largest in the mouth phase, with the smallest being the neck flexion angle. By contrast, in the spooning phase, the shoulder, elbow, and hip flexion were the smallest, with the largest being the neck flexion angle. These angles were significantly different between the mouth and spooning phases (p < 0.008, Bonferroni post hoc correction). Our results revealed that characteristic whole-body movements correspond to each phase of realistic eating in healthy individuals. This study provides useful kinematic data regarding normal eating movements, which may inform whole-body positioning and movement, improve the assessment of eating abilities in clinical settings, and provide a basis for future studies.
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Tatchev, Dragomir. "Multiphase approximation for small-angle scattering." Journal of Applied Crystallography 43, no. 1 (December 9, 2009): 8–11. http://dx.doi.org/10.1107/s0021889809048675.
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The two-phase approximation in small-angle scattering is well known and is still the dominant approach to data analysis. The intensity scattered at small angles is proportional to the second power of the difference between the scattering densities of the two phases. Nevertheless, scattering contrast variation techniques are widely used, and they are obviously suitable for multiphase systems or systems with gradually varying scattering density, since if no parasitic scattering contributions are present the scattering contrast variation would only change a proportionality coefficient. It is shown here that the scattered intensity at small angles of a multiphase system can be represented as a sum of the scattering of two-phase systems and terms describing interference between all pairs of phases. Extracting two-phase scattering patterns from multiphase samples by contrast variation is possible. These two-phase patterns can be treated with the usual small-angle scattering formalism. The case of gradually varying scattering density is also discussed.
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Pan, Junxing, Jin Sun, and Xiao-Gang He. "𝜃23 = π/4 and δ = −π/2 in neutrino mixing, which convention?" International Journal of Modern Physics A 34, no. 35 (December 20, 2019): 1950235. http://dx.doi.org/10.1142/s0217751x1950235x.
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Considerable information has been obtained about neutrino mixing matrix. Present data show that in the particle data group (PDG) parametrization, the 2–3 mixing angle and the CP violating phase are consistent with [Formula: see text] and [Formula: see text], respectively. A lot of efforts have been devoted to constructing models in realizing a mixing matrix with these values. However, the particular angles and phase are parametrization convention dependent. The meaning about the specific values for mixing angle and phase needs to be clarified. Using the well-known nine independent ways of parametrizing the mixing matrix, we show in detail how the mixing angles and phase change with conventions even with the 2–3 mixing angle to be [Formula: see text] and the CP violating phase to be [Formula: see text]. The original Kobayashi–Maskawa and an additional one belong to such a category. The other 6 parametrizations have mixing angles and phase very different values from those in the PDG parametrization although the physical effects are the same. Therefore one should give the specific parametrization convention when making statements about values for mixing angles and phase.
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Ellinas, Demosthenes. "Quantum Phase Angles and su(∞)." Journal of Modern Optics 38, no. 12 (December 1991): 2393–99. http://dx.doi.org/10.1080/09500349114552541.
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Anandan, J., and Y. Aharonov. "Geometric quantum phase and angles." Physical Review D 38, no. 6 (September 15, 1988): 1863–70. http://dx.doi.org/10.1103/physrevd.38.1863.
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Chung, Young Jin, Gi Hun Lee, and Hyeon Gyu Beom. "Atomistic Insights into the Phase Transformation of Single-Crystal Silicon during Nanoindentation." Nanomaterials 12, no. 12 (June 16, 2022): 2071. http://dx.doi.org/10.3390/nano12122071.
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The influence of the indenter angle on the deformation mechanisms of single-crystal Si was analyzed via molecular dynamics simulations of the nanoindentation process. Three different types of diamond conical indenters with semi-angles of 45°, 60°, and 70° were used. The load–indentation depth curves were obtained by varying the indenter angles, and the structural phase transformations of single-crystal Si were observed from an atomistic view. In addition, the hardness and elastic modulus with varying indenter angles were evaluated based on the Oliver–Pharr method and Sneddon’s solution. The simulation results showed that the indenter angle had a significant effect on the load–indentation depth curves, which resulted from the strong dependence of the elastic and plastic deformation ratios on the indenter angle during indentations.
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Xi, Zhi Jun, Gang Li, and Li Ming Lu. "Fabrication of Ultrahydrophobic ZnO by Vapor Phase Transport." Advanced Materials Research 282-283 (July 2011): 753–56. http://dx.doi.org/10.4028/www.scientific.net/amr.282-283.753.
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A ultrahydrophobic ZnO film was synthesized on the Si substrates by a novel vapor phase transport method. The surface structural properties of as-synthesized ZnO film was characterized using scanning electron micrograph (SEM). The contact angles and the rolling angles on such films were measured through an optical contact angle meter. Wettability studies revealed the films exhibited a ultrahydrophobic behaviour with a higher contact angle of 166.8°±6.8° and lower rolling angle of less than 2°-a water droplet moved easily on the surface. SEM showed that compared with pure smooth nickel surface, a lotus-like structrure with micro-nano hierarchical papillae was obviously observed on the ultrahydrophobic ZnO film surface. Such a speccial surface microstructure may result in the ultrahydrophobicity.
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Fischer, I. S., and R. N. Paul. "Kinematic Displacement Analysis of a Double-Cardan-Joint Driveline." Journal of Mechanical Design 113, no. 3 (September 1, 1991): 263–71. http://dx.doi.org/10.1115/1.2912778.
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The input-output displacement relations of two Cardan joints arranged in series on a driveline has been investigated in detail, including the effects of unequal joint angles, the phase angle between the two Cardan joints and also such manufacturing tolerance errors as nonright angle moving link lengths and offset joint axes. A combined Newton-Raphson method and Davidon-Fletcher-Powell optimization algorithm using dual-number coordinate-transformation matrices was employed to perform the analysis. An experiment was conducted to validate the results of the analysis. The apparatus consisted of a double-Cardan-joint driveline whose rotations were measured by optical shaft encoders that were sampled by a computer data-acquisition system. The equipment was arranged so that the phase angle between the joints and the offset angles between the shafts at each of the two joints could be readily varied. The “relative phase angle,” the difference between the phase angle of the two joints and the angle between the planes defined by the input and intermediate and the intermediate and output shafts, was found to be the significant factor. If the offset angles at both Cardan joints are equal, the double-Cardan-joint driveline functions as a constant-velocity coupling when the magnitude of the relative phase angle is zero. If the offset angles at the two Cardan joints are unequal, a condition prevailing in the important front-wheel-drive automobile steering-column application, then fluctuation in output velocity for a constant input velocity is minimized although not eliminated for zero relative phase angle.
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Biondi, Biondo. "Angle-domain common-image gathers from anisotropic migration." GEOPHYSICS 72, no. 2 (March 2007): S81—S91. http://dx.doi.org/10.1190/1.2430561.
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I present a general methodology for computing angle-domain common-image gathers (ADCIGs) in conjunction with anisotropic wavefield-continuation migration. The method is based on transforming the prestack image from the subsurface-offset domain to the angle domain using slant stacks. The processing sequence is the same as that for computing ADCIGs for the isotropic case, though the interpretation of the relationship between the slopes measured in the prestack image and the aperture angles is more complex. I demonstrate that the slopes measured by performing slant stacks along the subsurface-offset axis of the prestack image provide a good approximation of the phase aperture angles, and they are exactly equal to the phase aperture angles for flat reflectors in vertical transversly isotropic (VTI) media. In the general case of dipping reflectors, the angles computed using slant stacks can be easily corrected by applying the relationships that I present in this paper, and the accurate aperture angles can be determined as a function of the reflector dip and anisotropic slowness at the reflector. I derive these relationships from both plane-wave and ray viewpoints. This theoretical development links the kinematics in ADCIGs with migration-velocity errors. I apply the proposed method to compute ADCIGs from the prestack image obtained by anisotropic migration of a 2D line recorded in the Gulf of Mexico. I analyze the error introduced by neglecting the difference between the true phase aperture angle and the angle computed through slant stacks, showing that, at least for this data set, these errors are negligible and can be safely ignored. In contrast, group aperture angles can be quite different from phase aperture angles; thus, ignoring the distinction between these two angles can be detrimental to practical applications.
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PINIT, Pichet, Susumu TOBITA, and Eisaku UMEZAKI. "1467 Effect of Phase Angles on Determination of Principal-Stress Directions by Three-Step Color Phase Shifting." Proceedings of the JSME annual meeting 2005.1 (2005): 351–52. http://dx.doi.org/10.1299/jsmemecjo.2005.1.0_351.
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Zhu, Yaguang, and Tong Guo. "Galloping Trajectory Generation of a Legged Transport Robot Based on Energy Consumption Optimization." Journal of Robotics 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/9645730.
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Legged walking robots have very strong operation ability in the complex surface and they are very suitable for transportation of tools, materials, and equipment in unstructured environment. Aiming at the problems of energy consumption of legged transport robot during the fast moving, a method of galloping trajectory planning based on energy consumption optimization is proposed. By establishing transition angle polynomials of flight phase, lift-off phase, and stance phase and constraint condition between each state phase, the locomotion equations of the ellipse trajectory are derived. The transition angle of each state phase is introduced into the system energy consumption equations, and the energy optimization index based on transition angles is established. Inverse kinematics solution and trajectory planning in one gait cycle are applied to genetic algorithm process to solve the nonlinear programming problem. The results show that the optimized distribution of transition angles of state phases is more reasonable, and joint torques and system energy consumption are reduced effectively. Thus, the method mentioned above has a great significance to realize fast operation outdoors of transport robot.
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Rozhkov, V., L. Taran, D. Okun, L. Riadova, and V. Shutieiev. "Influence technique of the take-off phase on the flight phase of the hop in the female triple jump among elite athletes." Scientific Journal of National Pedagogical Dragomanov University. Series 15. Scientific and pedagogical problems of physical culture (physical culture and sports), no. 11(157) (December 1, 2022): 126–29. http://dx.doi.org/10.31392/npu-nc.series15.2022.11(157).29.
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The article discusses relationships between biomechanical parameters techniques take-off phase and flight phase of the hop among the qualified women specializing in triple jump. As a result of correlation analyses was determined that if research women faster put leg on the support, they will have more initial velocity of the total center of mass of the bodies r=0,955, reducing values dilution of the hips during flight phase of the hop r=-0,773, decrease time of flight phase of the hop r=-0,788 and increases long of the hop r=0,793.
If athletes spend more time on take-off phase, they will have more initial velocity of the total center of mass of the bodies r=0,770.
Take-off angle influences on such parameter’s techniques of flight phase of the hop as: velocity of the total center of mass of the body’s r=0,721, angle between thighs r=-0,722. The correlation coefficient showed that if research athletes have more take-off angle they will have more velocity of the total center mass of the body and less angle between thighs during flight phase of the hop.
Determined direct correlation between angle between hop at the take-off phase and angle between hop at the flight phase of the hop r=0,717. If women athletes have more angles between thighs at the take-off phase, they will have more angles between thighs at flight phase of the hop.
Determined that for effective implementation phase of the hop during techniques trainings should more time spend on improvement angles parameters of the take-off, increase the velocity of the put leg on support, and less time of the take-off phase.
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Longbiao, Li. "Comparisons of thermomechanical fatigue hysteresis loops of fiber-reinforced ceramic-matrix composites subjected to different phase angles." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 6 (June 3, 2018): 2015–32. http://dx.doi.org/10.1177/0954406218780139.
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In this paper, comparisons of thermomechanical fatigue hysteresis loops of fiber-reinforced ceramic-matrix composites (CMCs) subjected to different phase angles of θ = 0, π/3, π/2, and π have been investigated. The shape, location, and area of fatigue hysteresis loops are affected by the phase angle under the thermomechanical cyclic loading. The effects of fiber volume fraction, fatigue peak stress, matrix crack spacing, interface frictional coefficient, and interface debonded energy on the thermomechanical fatigue hysteresis loops and fiber/matrix interface slip of different phase angles are discussed. The fatigue hysteresis loops of cross-ply CMCs under the phase angles of θ = 0 and π are predicted for different fatigue peak stresses and cycle numbers.
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Liu, Jie, Xiang Bo Li, Jia Wang, and Shou Biao Li. "The Evaluation of Organic Coating with Artificial Defect Degradation with EIS Measurement: Phase Angle at High Frequencies." Advanced Materials Research 194-196 (February 2011): 2027–30. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.2027.
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Electrochemical impedance spectra (EIS) of two kinds of damage rate samples in natural seawater were measured and the relations between coating resistances and phase angles at high frequencies were analyzed. The results indicated that for the coating systems studied, the variation of phase angles at 14 kHz with immersion time was very close to the variation of coating resistance, hence may qualitatively reflect the coating with artificial defect degradation. This approach contains no error in calculation and the special phase angle parameters could be extracted easily from the EIS measured data. These phase angle parameters may be used as quick measurements to evaluate coating with artificial defect performance.
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Fan, Su Bo, Qun Yi Zhu, Xing Ying Zhu, and Zheng Qi Li. "Study on Gas/particle Flows in a Down-Fired Boiler with Swirl Burners: Influence of Different Outer Secondary Air Vane Angle." Advanced Materials Research 614-615 (December 2012): 149–56. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.149.
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The gas-solid multi-phase flow is measured in a 300MW down-fired bolier cold model with swirl burners by two-dimensional phase Doppler velocimetry(PDA), concluded the influence of different outer secondary air vane angles on the multi-phase flow characteristics in the furnace. For vane angles of 25°, the vertical direction average velocity is high and fluctuating velocity is low, the reach of the downward airflow is deeper, primary air and secondary air mix slowly, the horizontal direction average velocity is high and fluctuating velocity is low, solid phased particles spread slowly and mix with the rewind air weakly, this is against to the ignition of pulverized coal. For vane angles of 35°, the vertical direction average velocity decrease and decay faster, fluctuating velocity increase slightly, the horizontal direction average velocity and fluctuating velocity increased slightly, solid phased particles spread quickly and mixed with the rewind air quickly, the ignition of pulverized coal increase. For vane angles of 55°, the recirculation zone appear in the burner nozzle region, the vertical direction fluctuating velocity increase significantly, average velocity decrease and decay quickly, the downward airflow turn upwards before mixing with gas, the horizontal direction average velocity high and fluctuating velocity is higher, solid phased particles spread more quickly, mixed with the rewind air more quickly, this will erode the water wall and throat, cause the water wall slagging. Considering various factors, the best outer secondary air vane angle is 35° in the operation of boiler.
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Gundersen, Håkon, Hans Petter Leinaas, and Christian Thaulow. "Collembola cuticles and the three-phase line tension." Beilstein Journal of Nanotechnology 8 (August 18, 2017): 1714–22. http://dx.doi.org/10.3762/bjnano.8.172.
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The cuticles of most springtails (Collembola) are superhydrophobic, but the mechanism has not been described in detail. Previous studies have suggested that overhanging surface structures play an important role, but such structures are not a universal trait among springtails with superhydrophobic cuticles. A novel wetting experiment with a fluorescent dye revealed the extent of wetting on exposed surface structures. Using simple wetting models to describe the composite wetting of the cuticular surface structures results in underestimating the contact angles of water. Including the three-phase line tension allows for a prediction of contact angles in the observed range. The discrepancy between the contact angle predicted by simple models and those observed is especially large in the springtail Cryptopygus clavatus which changes, seasonally, from superhydrophobic to wetting without a large change in surface structure; C. clavatus does not have overhanging surface structures. This large change in observed contact angles can be explained with a modest change of the three-phase line tension.
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Masoumzadeh, N., L. Kolokolova, C. Tubiana, M. R. El-Maarry, S. Mottola, C. Güttler, C. Snodgrass, et al. "Phase-curve analysis of comet 67P/Churyumov-Gerasimenko at small phase angles." Astronomy & Astrophysics 630 (September 20, 2019): A11. http://dx.doi.org/10.1051/0004-6361/201834845.
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Aims. The Rosetta-OSIRIS images acquired at small phase angles in three wavelengths during the fly-by of the spacecraft on 9–10 April 2016 provided a unique opportunity to study the opposition effect on the surface of comet 67P/Churyumov-Gerasimenko (67P). Our goal is to study phase curves of the nucleus at small phase angles for a variety of surface structures to show the differences in their opposition effect and to determine which surface properties cause the differences. Methods. We used OSIRIS NAC images that cover the Ash-Khepry-Imhotep region to extract the phase curve, that is, the reflectance of the surface as a function of phase angle. We selected six regions of interest (ROIs) and derived the phase curves for each ROI. We fit a linear-exponential function to the phase curves. The resulting model parameters were then interpreted by spectrophotometric, geomorphological, and phase-ratio analyses, and by investigating the influence of structural and textural properties of the surface. Results. We find evidence for the opposition effect (deviation of the phase curve from linear behavior) in phase curves for all areas. We found an anticorrelation between the phase ratio and reflectance in a small phase angle range. This provides evidence for the shadow-hiding effect. We conclude that the decrease in the slope of the phase ratio versus reflectance indicates a decrease in the proportion of shadowed regions and reduces the contribution of the shadow-hiding effect. Large uncertainties in the determination of the opposition effect parameters with respect to wavelength do not allow us to conclusively claim coherent backscattering in the opposition effect phenomenon. Based on the two analyses, we conclude that the opposition effect of comet 67P in the Ash-Khepry-Imhotep region is mainly affected by shadow-hiding.
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Wang, Yong, Jingmin Dai, and Dongyang An. "Numerical Investigations on Melting Behavior of Phase Change Material in a Rectangular Cavity at Different Inclination Angles." Applied Sciences 8, no. 9 (September 12, 2018): 1627. http://dx.doi.org/10.3390/app8091627.
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This paper investigates the melting process of phase change material in a rectangular cavity at different inclination angles. Paraffin is used as a phase change material in this study. One side of the cavity is heated while the other sides are considered to be adiabatic. The investigated angles of inclination include 0° (bottom horizontal heating), 30°, 60°, 90° (vertical heating), 120°, 150° and 180° (top horizontal heating). Shapes of the solid liquid interface and temperature variations during the melting process were discussed for all the inclination angles. The results reveal that the inclination angles have a significant impact on the melting behavior of paraffin. As the angle increases from 0° to 180°, the complete melting time increases non-linearly.
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Scanziani, Alessio, Qingyang Lin, Abdulla Alhosani, Martin J. Blunt, and Branko Bijeljic. "Dynamics of fluid displacement in mixed-wet porous media." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, no. 2240 (August 2020): 20200040. http://dx.doi.org/10.1098/rspa.2020.0040.
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We identify a distinct two-phase flow invasion pattern in a mixed-wet porous medium. Time-resolved high-resolution synchrotron X-ray imaging is used to study the invasion of water through a small rock sample filled with oil, characterized by a wide non-uniform distribution of local contact angles both above and below 90 ° . The water advances in a connected front, but throats are not invaded in decreasing order of size, as predicted by invasion percolation theory for uniformly hydrophobic systems. Instead, we observe pinning of the three-phase contact between the fluids and the solid, manifested as contact angle hysteresis, which prevents snap-off and interface retraction. In the absence of viscous dissipation, we use an energy balance to find an effective, thermodynamic, contact angle for displacement and show that this angle increases during the displacement. Displacement occurs when the local contact angles overcome the advancing contact angles at a pinned interface: it is wettability which controls the filling sequence. The product of the principal interfacial curvatures, the Gaussian curvature, is negative, implying well-connected phases which is consistent with pinning at the contact line while providing a topological explanation for the high displacement efficiencies in mixed-wet media.
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Negussey, D., W. K. D. Wijewickreme, and Y. P. Vaid. "Constant-volume friction angle of granular materials." Canadian Geotechnical Journal 25, no. 1 (February 1, 1988): 50–55. http://dx.doi.org/10.1139/t88-006.
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The postulate that the constant-volume friction angle [Formula: see text] of a granular material is unique and a function of mineral composition is verified experimentally. Granular materials comprised of particles ranging from minerals to metals are tested in a ring shear apparatus. Test samples are subjected to large shear displacements until a constant lower bound friction angle [Formula: see text] is mobilized. Possible effects of confining pressure, initial packing density, gradation, and particle shape on the value of [Formula: see text] are investigated. Friction angles mobilized in drained shear at the instant of maximum contraction and in undrained shear at phase transformation and steady state are compared with [Formula: see text] values. The experimental results confirm a broader fundamental significance of [Formula: see text] as a material parameter in that it is a consistent minimum drained friction angle equal to friction angles mobilized at phase transformation and steady state in undrained shear. Key words: granular materials, sand, friction angles, constant volume, steady state, phase transformation state, ring shear test.
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Erbil, H. Yildirim. "Dependency of Contact Angles on Three-Phase Contact Line: A Review." Colloids and Interfaces 5, no. 1 (February 1, 2021): 8. http://dx.doi.org/10.3390/colloids5010008.
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The wetted area of a sessile droplet on a practical substrate is limited by the three-phase contact line and characterized by contact angle, contact radius and drop height. Although, contact angles of droplets have been studied for more than two hundred years, there are still some unanswered questions. In the last two decades, it was experimentally proven that the advancing and receding contact angles, and the contact angle hysteresis of rough and chemically heterogeneous surfaces, are determined by interactions of the liquid and the solid at the three-phase contact line alone, and the interfacial area within the contact perimeter is irrelevant. However, confusion and misunderstanding still exist in this field regarding the relationship between contact angle and surface roughness and chemical heterogeneity. An extensive review was published on the debate for the dependence of apparent contact angles on drop contact area or the three-phase contact line in 2014. Following this old review, several new articles were published on the same subject. This article presents a review of the novel articles (mostly published after 2014 to present) on the dependency of contact angles on the three-phase contact line, after a short summary is given for this long-lasting debate. Recently, some improvements have been made; for example, a relationship of the apparent contact angle with the properties of the three-phase line was obtained by replacing the solid–vapor interfacial tension term, γSV, with a string tension term containing the edge energy, γSLV, and curvature of the triple contact line, km, terms. In addition, a novel Gibbsian thermodynamics composite system was developed for a liquid drop resting on a heterogeneous multiphase and also on a homogeneous rough solid substrate at equilibrium conditions, and this approach led to the same conclusions given above. Moreover, some publications on the line energy concept along the three-phase contact line, and on the “modified” Cassie equations were also examined in this review.
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Mu, Xue Jie, Xing Wei Li, and Na Duan. "Dynamic Simulation and Analysis of Different Phase Synchronous Rotor Mixing Process." Key Engineering Materials 561 (July 2013): 279–84. http://dx.doi.org/10.4028/www.scientific.net/kem.561.279.
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Contrast and analysis of the influence that synchronous rotor mixer’s two phase angles 90° and 180° to the mixing effect using special visco-elasticity fluid software--Polyflow. The results show that 90° phase angle rotor could promote compound mixing, and improve mixing rubber’s uniformity, and its mixing effect is better than synchronous rotor with 180° phase angle.
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Behura, Jyoti, and Ilya Tsvankin. "Role of the inhomogeneity angle in anisotropic attenuation analysis." GEOPHYSICS 74, no. 5 (September 2009): WB177—WB191. http://dx.doi.org/10.1190/1.3148439.
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The inhomogeneity angle (the angle between the real and imaginary parts of the wave vector) is seldom taken into account in estimating attenuation coefficients from seismic data. Wave propagation through the subsurface, however, can result in relatively large inhomogeneity angles [Formula: see text], especially for models with significant attenuation contrasts across layer boundaries. Here we study the influence of the angle [Formula: see text] on phase and group attenuation in arbitrarily anisotropic media using the first-order perturbation theory verified by exact numerical modeling. Application of the spectral-ratio method to transmitted or reflected waves yields the normalized group attenuation coefficient [Formula: see text], which is responsible for amplitude decay along seismic rays. Our analytic solutions show that for a wide range of inhomogeneity angles, the coefficient [Formula: see text] is close to the normalized phase attenuation coefficient [Formula: see text] computed for [Formula: see text] [Formula: see text]. The coefficient[Formula: see text] can be inverted directly for the attenuation-anisotropy parameters, so no knowledge of the inhomogeneity angle is required for attenuation analysis of seismic data. This conclusion remains valid even for uncommonly high attenuation with the quality factor [Formula: see text] less than 10 and strong velocity and attenuation anisotropy. However, the relationship between group and phase attenuation coefficients becomes more complicated for relatively large inhomogeneity angles approaching so-called ‘‘forbidden directions.’’ We also demonstrate that the velocity function remains practically independent of attenuation for a wide range of small and moderate angles [Formula: see text]. In principle, estimation of the attenuation-anisotropy parameters from the coefficient [Formula: see text] requires computation of the phase angle, which depends on the anisotropic velocity field. For moderately anisotropic models, however, the difference between the phase and group directions should not significantly distort the results of attenuation analysis.
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Narasimha, S., and Surender Reddy Salkuti. "An improved closed loop hybrid phase shift controller for dual active bridge converter." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 2 (April 1, 2020): 1169. http://dx.doi.org/10.11591/ijece.v10i2.pp1169-1178.
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In this paper, a new closed loop hybrid phase shift control is proposed for dual active bridge (DAB) converter with variable input voltage. The extended phase shift (EPS) control is applied when load gets heavy enough and the secondary side phase shift angle decreases to zero. When this modified DAB converter operates at light loads, the triple phase shift (TPS) modulation method is applied, and the added control freedom is the secondary phase shift angle between the two-secondary side switching legs. The hybrid phase shift control (HPS) scheme is a combination of EPS and TPS modulations, and it provides a very simple closed form implementation for the primary and secondary side phase shift angles. Depending on the application by changing the phase shift angles we can achieve Buck or Boost operation. A characteristic table feedback control method has been used for closed loop operation. By using 1D look up table the proposed DAB converter provides constant 400V for any given input voltage.
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Garroway, A. N. "Phase enhancement for precise determination of small radiofrequency phase angles." Journal of Magnetic Resonance (1969) 63, no. 3 (July 1985): 504–11. http://dx.doi.org/10.1016/0022-2364(85)90240-9.
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Ciarniello, M., M. C. De Sanctis, A. Raponi, B. Rousseau, A. Longobardo, J. Y. Li, S. E. Schröder, et al. "Ceres observed at low phase angles by VIR-Dawn." Astronomy & Astrophysics 634 (February 2020): A39. http://dx.doi.org/10.1051/0004-6361/201936492.
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Context. Particulate surfaces exhibit a surge of reflectance at low phase angles, a phenomenon referred to as the opposition effect (OE). Two mechanisms are recognized as responsible for the OE: shadow hiding (SH) and coherent backscattering. The latter is typically characterized by a small angular width of a few degrees at most and according to the theoretical prediction should exhibit wavelength and albedo dependence. Aims. We characterize the OE on the surface of Ceres using Dawn Visible InfraRed mapping spectrometer hyperspectral images at low phase angles. Furthermore, this dataset, coupled with previous observations, allows us to perform a complete spectrophotometric modeling at visual-to-infrared (VIS-IR) wavelengths (0.465–4.05 μm) in the broad phase angle range ≈0°−132°. Methods. We applied Hapke’s theory to the average phase curve for Ceres. Disk-resolved properties of the OE were investigated through an empirical model. Results. Across the investigated phase angle interval, Ceres’ average phase curve exhibits a smaller back-scattering contribution for increasing wavelengths. This determines a progressive spectral reddening at larger phase angles that we hypothesize as being related to the effect of submicron roughness on the grain surface. In the OE region, the shape of the phase curves is fairly constant across the VIS range and no sharp opposition surge at very small phase angles (α < 2°) can be recognized. This would suggest a major contribution from SH to Ceres’ OE. Assuming SH as the dominant mechanism, from the OE angular width we infer a high surface porosity (≈0.9), which appears in good qualitative agreement with Ceres’ low thermal inertia. Thanks to the OE observations we derive Ceres’ VIS-IR geometric albedo with a reference value at 0.55 μm of 0.098 ± 0.007. Mapping of the VIS normal albedo and OE angular width across a portion of the surface of Ceres does not reveal a spatial correlation between these quantities, consistent with SH dominating in the α = 0°−7° interval. The comparison of Ceres’ V -band magnitude curve with that of other asteroids indicates that Ceres’ OE is typical of a low-albedo object and compatible with the C-class type.
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Minh, D. B., L. D. Hai, T. L. Anh, and V. D. Quoc. "Electromagnetic Torque Analysis of SRM 12/8 by Rotor/Stator Pole Angle." Engineering, Technology & Applied Science Research 11, no. 3 (June 9, 2021): 7187–90. http://dx.doi.org/10.48084/etasr.4168.
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This paper presents the harmonic torque reduction by the different rotor pole angles of a three-phase 12/8 switched reluctance motor via an analytical model and simulation method. Improving torque performance by stator and rotor angles was applied for three-phase switched reluctance motor at stator pole/rotor pole ratios of 6/4, 8/12, 18/12, and 24/18. The average torque and the torque ripple effect by stator and rotor pole embrace have been recently studied in many projects. Due to the fact that leakage flux, flux density, and inductance are affected by the stator and rotor pole angles non-linear and linear leakage flux curves occur. Many stator and rotor pole angle combinations for the three-phase switched reluctance motor have already been done via a finite element method. In this paper, turn-on and turn-off angles will be figured based on stator and rotor pole embraces.
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HUO, GUANGWEN, TONGYI ZHANG, GUANGHUA CHENG, and WEI ZHAO. "CALCULATION OF EFFECTIVE NONLINEAR COEFFICIENT IN BIBO FOR SPONTANEOUS PARAMETRIC DOWN CONVERSION." Journal of Nonlinear Optical Physics & Materials 22, no. 01 (March 2013): 1350010. http://dx.doi.org/10.1142/s0218863513500100.
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We theoretically investigate the effective nonlinear coefficient d eff of spontaneous parametric down-conversion (SPDC) process in biaxial nonlinear crystal BiB3O6 (BIBO). We solve the Fresnel equations in the collinear degenerate down-converted configuration, and get the relations of phase-matching angles. Considering the double phase-matching, we compute the phase-matching angles with different wavelength. Furthermore, we simplify the expression of effective nonlinear coefficient out of the principal planes, and numerically calculate it varying with the angle and wavelength. These results indicate that there are three effective phase-matching schemes for SPDC which can be used to construct a system to generate entangled photon pairs.
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Fritzsch, Harald. "Flavor mixing of quarks and a new texture." Modern Physics Letters A 36, no. 13 (April 1, 2021): 2150097. http://dx.doi.org/10.1142/s0217732321500978.
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The flavor mixing of the quarks is described by the CKM matrix, which is parametrized by three mixing angles and one phase parameter. We discuss a new texture for the two mass matrices of the six quarks. The three flavor mixing angles can be calculated — they are functions of the ratios of the quark masses. The third mixing angle is given by the CKM matrix element [Formula: see text]. We find: [Formula: see text]. The calculated mixing angles agree with the mixing angles, measured in many experiments.
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de Ruiter, C. J., R. D. Kooistra, M. I. Paalman, and A. de Haan. "Initial phase of maximal voluntary and electrically stimulated knee extension torque development at different knee angles." Journal of Applied Physiology 97, no. 5 (November 2004): 1693–701. http://dx.doi.org/10.1152/japplphysiol.00230.2004.
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We investigated the capacity for torque development and muscle activation at the onset of fast voluntary isometric knee extensions at 30, 60, and 90° knee angle. Experiments were performed in subjects ( n = 7) who had high levels (>90%) of activation at the plateau of maximal voluntary contractions. During maximal electrical nerve stimulation (8 pulses at 300 Hz), the maximal rate of torque development (MRTD) and torque time integral over the first 40 ms (TTI40) changed in proportion with torque at the different knee angles (highest values at 60°). At each knee angle, voluntary MRTD and stimulated MRTD were similar ( P < 0.05), but time to voluntary MRTD was significantly longer. Voluntary TTI40 was independent ( P > 0.05) of knee angle and on average (all subjects and angles) only 40% of stimulated TTI40. However, among subjects, the averaged (across knee angles) values ranged from 10.3 ± 3.1 to 83.3 ± 3.2% and were positively related ( r2 = 0.75, P < 0.05) to the knee-extensor surface EMG at the start of torque development. It was concluded that, although all subjects had high levels of voluntary activation at the plateau of maximal voluntary contraction, among subjects and independent of knee angle, the capacity for fast muscle activation varied substantially. Moreover, in all subjects, torque developed considerably faster during maximal electrical stimulation than during maximal voluntary effort. At different knee angles, stimulated MRTD and TTI40 changed in proportion with stimulated torque, but voluntary MRTD and TTI40 changed less than maximal voluntary torque.
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Shi, Yipeng, Hafsa Khurshid, Dylan B. Ness, and John B. Weaver. "Harmonic phase angles used for nanoparticle sensing." Physics in Medicine & Biology 62, no. 20 (October 4, 2017): 8102–15. http://dx.doi.org/10.1088/1361-6560/aa8a4a.
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Wilson, Robert E., and Patrick S. Sterlina. "Verification of Measured Transmission System Phase Angles." IEEE Power Engineering Review 16, no. 10 (October 1996): 48–49. http://dx.doi.org/10.1109/mper.1996.4311013.
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Myers, Roy V. "Polarization of comets at small phase angles." Icarus 63, no. 2 (August 1985): 206–16. http://dx.doi.org/10.1016/0019-1035(85)90005-3.
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Wilson, R. E., and P. S. Sterlina. "Verification of measured transmission system phase angles." IEEE Transactions on Power Delivery 11, no. 4 (1996): 1743–47. http://dx.doi.org/10.1109/61.544252.
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Berry, M. V. "Classical adiabatic angles and quantal adiabatic phase." Journal of Physics A: Mathematical and General 18, no. 1 (January 11, 1985): 15–27. http://dx.doi.org/10.1088/0305-4470/18/1/012.
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Liu, Zhen, Xin Chen, Zhenhua Wei, Tianpeng Liu, Linlin Li, and Bo Peng. "Ambiguity Analysis and Resolution for Phase-Based 3D Source Localization under Given UCA." International Journal of Antennas and Propagation 2019 (April 18, 2019): 1–12. http://dx.doi.org/10.1155/2019/4743829.
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Under uniform circular array, by employing some algebraic schemes to exploit the phase information of receiving data and further estimate the source’s three-dimensional (3D) parameters (azimuth angle, elevation angle, and range), a series of novel phase-based algorithms with low computational complexity have been proposed recently. However, when the array diameter is larger than source’s half-wavelength, these algorithms would suffer from phase ambiguity problem. Even so, there always exist certain positions, where the source’s parameters can still be determined with nonambiguity. Therefore, this paper first investigates the zone of ambiguity-free source 3D localization using phase-based algorithms. For the ambiguous zone, a novel ambiguity resolution algorithm named ambiguity traversing and cosine matching (ATCM) is presented. In ATCM, the phase differences of centrosymmetric sensors under different ambiguities are utilized to match a cosine function with sensor number-varying, and the source’s unambiguous rough angles can be derived from amplitude and initial phase of the cosine function. Then, the unambiguous angles are employed to resolve the phase ambiguity of the phase-based 3D parameter estimation algorithm, and the source’s range as well as more precise angles can be achieved. Theoretical analyses and numerical examples show that, apart from array diameter and source’s frequency, the sensor number and spacing of employed sensors are two key factors determining the unambiguous zone. Moreover, simulation results demonstrate the effectiveness and satisfactory performance of our proposed ambiguity resolution algorithm.
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Schreier, Julia, Orkun Furat, Murat Cankaya, Volker Schmidt, and Ulrich Bröckel. "Automated Evaluation of Contact Angles in a Three-Phase System of Selective Agglomeration in Liquids." Image Analysis & Stereology 39, no. 3 (November 25, 2020): 187–96. http://dx.doi.org/10.5566/ias.2403.
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This study aims to an automated evaluation of contact angles in a three-phase system of selective agglomeration in liquids. Wetting properties, quantified by contact angles, are essential in many industries and their processes. Selective agglomeration as a three-phase system consists of a suspension liquid, a heterogeneous solid phase and an immiscible binding liquid. It offers the chance of establishing more efficient separation processes because of the shape-dependent wetting properties of fine particles (size ≤ 10 µm). In the present paper, an experimental setup for contact angle measurements of fine particles based on the Sessile Drop Method is described. Moreover, a new algorithm is discussed, which can be used to automatically compute contact angles from image data captured by a high-speed camera. The algorithm uses a marker-based watershed transform to segment the image data into regions representing the droplet, the carrier plate coated by fine particles, and the background. The main idea is a parametric modelling approach forthe time-dependent droplet’s contour by an ellipse.The results show that the development of the dynamic contact angles towards a static contact angle can be efficiently determined based on this novel technique. These findings are useful for a detailed discrimination of wetting properties of spherical and irregularly shaped particles as well as their wetting kinetics. Also, a better understanding of selective agglomeration processes will be promoted by this user-friendly method.
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Kuhl, Adam, and Jianmin Qu. "A Technique to Measure Interfacial Toughness Over a Range of Phase Angles." Journal of Electronic Packaging 122, no. 2 (September 15, 1999): 147–51. http://dx.doi.org/10.1115/1.483147.
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An experimental technique using sandwiched Brazil-nut specimens to quantitatively characterize interfacial fracture toughness over a wide range of phase angles is presented. Specimens are made by sandwiching a thin layer of adhesive material between two metal substrates. Tensile loads are applied to the specimens at various loading angles. Through the use of fracture mechanics and finite element analysis, interfacial fracture toughness as a function of loading phase angle is determined from the experimentally obtained critical load and loading direction. The fracture toughness curves for several different Cu/adhesive systems are obtained. [S1043-7398(00)00302-9]
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Rouse, Adam G., and Marc H. Schieber. "Spatiotemporal distribution of location and object effects in reach-to-grasp kinematics." Journal of Neurophysiology 114, no. 6 (December 1, 2015): 3268–82. http://dx.doi.org/10.1152/jn.00686.2015.
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In reaching to grasp an object, the arm transports the hand to the intended location as the hand shapes to grasp the object. Prior studies that tracked arm endpoint and grip aperture have shown that reaching and grasping, while proceeding in parallel, are interdependent to some degree. Other studies of reaching and grasping that have examined the joint angles of all five digits as the hand shapes to grasp various objects have not tracked the joint angles of the arm as well. We, therefore, examined 22 joint angles from the shoulder to the five digits as monkeys reached, grasped, and manipulated in a task that dissociated location and object. We quantified the extent to which each angle varied depending on location, on object, and on their interaction, all as a function of time. Although joint angles varied depending on both location and object beginning early in the movement, an early phase of location effects in joint angles from the shoulder to the digits was followed by a later phase in which object effects predominated at all joint angles distal to the shoulder. Interaction effects were relatively small throughout the reach-to-grasp. Whereas reach trajectory was influenced substantially by the object, grasp shape was comparatively invariant to location. Our observations suggest that neural control of reach-to-grasp may occur largely in two sequential phases: the first determining the location to which the arm transports the hand, and the second shaping the entire upper extremity to grasp and manipulate the object.
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Bao, Hai, Jin Si Han, Shu De Zhang, and Yu Long Chen. "The Irremovable Properties Proof of Decaying DC Component for Dynamic Phasor Measurement." Advanced Materials Research 986-987 (July 2014): 1611–15. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.1611.
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Dynamic voltage can be described by two parts in time domain, sinusoidal steady state component and dynamic state component. The latter reflects the effect of the system’s characteristic root, and is also called decaying DC component. Decaying exponential signal has continuous spectrum, and this characteristic has a bad effect on the accuracy of phase angle’s measurement, therefore the idea of filtering the decaying exponential signal was proposed. To verify the possibility of this proposal, this paper analyzes the frequency formation of dynamic voltage signal mathematically, and points out that at the frequency of the sinusoidal component, measured voltage signal’s time domain description is the superposition of two sinusoidal signals with the same frequency, different phase angles and different amplitudes. This is the reason for the deviation between the measured voltage angle and the theoretical phase angle. The deviation angle not only shows the combined action of steady component and dynamic component, but also illustrates that the decaying exponential signal cannot be filtered out.
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Wang, Shuaijie, Yiru Wang, Yi-Chung (Clive) Pai, Edward Wang, and Tanvi Bhatt. "Which Are the Key Kinematic and Kinetic Components to Distinguish Recovery Strategies for Overground Slips Among Community-Dwelling Older Adults?" Journal of Applied Biomechanics 36, no. 4 (August 1, 2020): 217–27. http://dx.doi.org/10.1123/jab.2019-0285.
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Slip outcomes are categorized as either a backward loss of balance (LOB) or a no loss of balance (no-LOB) in which an individual does not take a backward step to regain their stability. LOB includes falls and nonfalls, while no-LOB includes skate overs and walkovers. Researchers are uncertain about which factors determine slip outcomes and at which critical instants they do so. The purpose of the study was to investigate factors affecting slip outcomes in proactive and early reactive phases by analyzing 136 slip trials from 68 participants (age: 72.2 [5.3] y, female: 22). Segment angles and average joint moments in the sagittal plane of the slipping limb were compared for different slip outcomes. The results showed that knee flexor, hip extensor, and plantar flexor moments were significantly larger for no-LOB than for LOB in the midproactive phase, leading to smaller shank-ground and foot-ground angles at the slip onset, based on forward dynamics. In the early reactive phase, the hip extensor and plantar flexor moments were larger for no-LOB than for LOB, and all segment angles were smaller for no-LOB. Our findings indicate that the shank angle and knee moment were the major determinants of slip outcomes in both proactive and reactive phases.
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Masad, Ihssan S., Sami Almashaqbeh, Othman Smadi, Mariam Abu Olaim, and Abeer Obeid. "Spinal Curvature and Lower Extremities Kinematics of Simulated Pregnancy during Stair Ascending and Descending." Journal of Biomimetics, Biomaterials and Biomedical Engineering 41 (April 2019): 11–22. http://dx.doi.org/10.4028/www.scientific.net/jbbbe.41.11.
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The purpose of this work is to investigate the effect of anteriorly-added mass to simulate pregnancy on lower extremities kinematic and lumbar and thoracic angles during stair ascending and descending. 18 healthy females ascended and descended, with and without a pseudo-pregnancy sac of 12 kg (experimental and control groups, respectively), a costume-made wooden staircase while instrumented with 20 reflective markers placed on the lower extremities and the spine. The movements were captured by 12 infrared cameras surrounding the staircase. Tracked position data were exported to MATLAB to calculate the required joints angles. SPSS was used to compare the ascent and descent phases of control group, and to find if there are any significant differences between control and experimental groups in the ascent phase as well as in the descent phase. When comparing the ascent and descent phases of control group, data revealed a higher hip flexion during ascending and greater ankle planter-flexion and dorsiflexion, lumbar, and thoracic angles during descending; however, no significant difference was shown in the knee flexion angle between ascending and descending. Non-pregnant data showed greater maximum hip flexion and ankle dorsiflexion during stair ascending compared to simulated-pregnant group; while ankle planter-flexion, knee flexion, and lumbar angle were greater for simulated-pregnant status. During stair descending, non-pregnant group had greater minimum hip flexion and ankle dorsiflexion compared to simulated pregnant group; while ankle planter-flexion, knee flexion, and maximum hip flexion were greater for simulated-pregnant group. However, the lumbar and thoracic angles were found to be similar for simulated-pregnant and non-pregnant groups during stair descending. In conclusion, the current study revealed important kinematic modifications pregnant women adopt while ascending and descending stairs at their final stage of pregnancy to increase their stability.
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Li, Gang. "Preparation of a Superhydrophobic Carbon Dilm by a Novel Vapor Phase Transport Process." Advanced Materials Research 168-170 (December 2010): 1065–68. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.1065.
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Extreme water repellency is greatly desired for anticontamination and self-cleaning applications in new building walling materials. A superhydrophobic carbon film was fabricated on the pure nickel substrates by a novel vapor phase transport method. The surface of morphologies of the pure nickel surface was characterized using a non-contact mode of atomic force microscope (AFM) and the structural properties of as-grown carbon film was characterized using scanning electron micrograph (SEM). The contact angles and the rolling angles on such films were measured through an optical contact angle meter. Wettability studies revealed the films exhibited a superhydrophobic behaviour with a higher contact angle of 160.7°±2.1° and lower rolling angle of less than 4°-a water droplet moved easily on the surface. SEM showed that compared with pure smooth nickel surface, a lotus-like structrure with micro-nano hierarchical papillae was obviously observed on the superhydrobic carbon film surface. Such a speccial surface microstructure may result in the superhydrophobicity.
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Li, L. B. "Comparisons of the Thermomechanical Fatigue Behavior of C/SIC and SIC/SIC Ceramic-Matrix Composites Subjected to Different Phase Angle." Journal of Mechanics 35, no. 02 (January 25, 2018): 209–23. http://dx.doi.org/10.1017/jmech.2017.111.
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ABSTRACTIn this paper, the comparisons of thermomechanical fatigue behavior of C/SiC and SiC/SiC fiber-reinforced ceramic-matrix composites (CMCs) subjected to different phase angles of θ = 0, π/3, π/2 and π have been investigated. The relationships between the fatigue damage mechanisms, phase angle, fatigue hysteresis dissipated energy, fatigue hysteresis modulus and fatigue peak strain, fiber/matrix interface debonding and sliding have been established. The differences between C/SiC and SiC/SiC composites under thermomechanical fatigue loading with different phase angles have been analyzed. The damage accumulation of 2.5D C/SiC and 2D SiC/SiC composites under thermomechanical fatigue loading have been predicted. With increasing of the phase angle, the fatigue hysteresis dissipated energy, fatigue peak strain and interface debonded length decrease for the SiC/SiC composite; however, for the C/SiC composite, the fatigue hysteresis dissipated energy, fatigue peak strain and the interface debonded length increase at the same cycle number.
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Stepanyan, M. A. "STUDY OF THE SWELLING OF THE PHOSPHOLIPID BILAYER, DEPENDING ON THE ANGLE BETWEEN THE INCLINATION OF THE DIPOLE FRAGMENTS AND THE PLANE OF THE LAMELLA." Proceedings of the YSU A: Physical and Mathematical Sciences 52, no. 3 (247) (December 17, 2018): 217–21. http://dx.doi.org/10.46991/pysu:a/2018.52.3.217.
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Using computer simulations and simultaneous X-ray diffraction at large and small angles, the dependence of the swelling coefficient of the phospholipid bilayer on the angle between the inclination of dipole fragments and the plane of the lamella was investigated. It was shown that in this case the balance between electrostatic, repulsive and van der Waals attraction forces is a particular importance. As the dipole angle increases, the repulsive forces of the electrostatic dipole-dipole interaction increase, resulting the increase of the bilayer thickness as a function of the number of –CH-groups in the phospholipid. At a certain angle the bilayer is destroyed. It is also shown that at certain small angles the bilayer takes a minimum thickness. In this case a phase transformation takes place and the system enters the “gel”-phase.
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Matsuzawa, Yuta, Takasuke Miyazaki, Yasufumi Takeshita, Naoto Higashi, Hiroyuki Hayashi, Sota Araki, Shintaro Nakatsuji, Seiji Fukunaga, Masayuki Kawada, and Ryoji Kiyama. "Effect of Leg Extension Angle on Knee Flexion Angle during Swing Phase in Post-Stroke Gait." Medicina 57, no. 11 (November 9, 2021): 1222. http://dx.doi.org/10.3390/medicina57111222.
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Background and Objectives: Leg extension angle is important for increasing the propulsion force during gait and is a meaningful indicator for evaluating gait quality in stroke patients. Although leg extension angle during late stance might potentially also affect lower limb kinematics during the swing phase, the relationship between these two remains unclear. This study aimed to investigate the relationship between leg extension angle and knee flexion angle during pre-swing and swing phase in post-stroke gait. Materials and Methods: Twenty-nine stroke patients walked along a 16 m walkway at a self-selected speed. Tilt angles and acceleration of pelvis and paretic lower limb segments were measured using inertial measurement units. Leg extension angle, consisting of a line connecting the hip joint with the ankle joint, hip and knee angles, and increments of velocity during pre-swing and swing phase were calculated. Correlation analysis was conducted to examine the relationships between these parameters. Partial correlation analysis adjusted by the Fugl-Meyer assessment-lower limb (FMA-LL) was also performed. Results: On the paretic side, leg extension angle was positively correlated with knee flexion angle during the swing phase (r = 0.721, p < 0.001) and knee flexion angle and increments of velocity during the pre-swing phase (r = 0.740–0.846, p < 0.001). Partial correlation analysis adjusted by the FMA-LL showed significant correlation between leg extension angle and knee flexion angle during the swing phase (r = 0.602, p = 0.001) and knee flexion angle and increments of velocity during the pre-swing phase (r = 0.655–0.886, p < 0.001). Conclusions: Leg extension angle affected kinematics during the swing phase in post-stroke gait regardless of the severity of paralysis, and was similar during the pre-swing phase. These results would guide the development of effective gait training programs that enable a safe and efficient gait for stroke patients.