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Alkadhimi, Aslam. "A novel and simple technique for correcting localised rotations in the early alignment stage". Journal of Orthodontics 47, nr 4 (27.08.2020): 338–44. http://dx.doi.org/10.1177/1465312520949553.
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Correcting severe tooth rotations can be challenging. There are many ways to de-rotate teeth with fixed or removable appliances. Mechanically, the best and most effective way is one that produces a two-force couple system to rotate a tooth around its centre of rotation (longitudinal axis). The aim of this article was to introduce a simple and efficient technique using a closed coil to correct localised tooth rotations in the early alignment stage, utilising a simple two-force couple system. Furthermore, some of the biomechanical principles concerning de-rotation will be revisited.
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Ye, Tingting, i Yangmin Li. "Synthesis of 2-DOF Decoupled Rotation Stage with FEA-Based Neural Network". Processes 11, nr 1 (6.01.2023): 192. http://dx.doi.org/10.3390/pr11010192.
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Transfer printing technology has developed rapidly in the last decades, offering a potential demand for 2-DOF rotation stages. In order to remove decoupling modeling, improve motion accuracy, and simplify the control method, the 2-DOF decoupled rotation stages based on compliant mechanisms present notable merits. Therefore, a novel 2-DOF decoupled rotation stage is synthesized of which the critical components of decoupling are the topological arrangement and a novel decoupled compound joint. To fully consider the undesired deformation of rigid segments, an FEA-based neural network model is utilized to predict the rotation strokes and corresponding coupling ratios, and optimize the structural parameters. Then, FEA simulations are conducted to investigate the static and dynamic performances of the proposed 2-DOF decoupled rotation stage. The results show larger rotation strokes of 4.302 mrad in one-axis actuation with a 1.697% coupling ratio, and 4.184 and 4.151 mrad in two-axis actuation with undesired Rz rotation of 0.014 mrad with fewer actuators than other works. In addition, the first natural frequency of 2151 Hz is also higher, enabling a wider working frequency range.
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Kurokawa, Hiroaki, Shinichi Kosugi, Takuya Fujinuma, Yuya Oishi, Takuma Miyamoto, Akira Taniguchi, Hiroshi Takemura i Yasuhito Tanaka. "Evaluation of Subtalar Joint’s Compensatory Function in Varus Ankle Osteoarthritis Using Globally Optimal Iterative Closest Points (Go-ICP)". Foot & Ankle Orthopaedics 7, nr 2 (kwiecień 2022): 247301142211035. http://dx.doi.org/10.1177/24730114221103584.
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Background: A previous study on 2-dimensional evaluation of the subtalar joint functioning in varus ankle osteoarthritis concluded that varus deformity was compensated for by the subtalar joint during early stages but not in the advanced stages. Although compensatory function is expected both along the axial and coronal planes, compensatory function in all 3 dimensions (3D) remains unevaluated. This study evaluated the 3D-compensatory function of a varus subtalar joint using Globally Optimal Iterative Closest Points (Go-ICP), a 3D-shape registration algorithm, after 3D-bone shape reconstruction using computed tomography. Methods: This study included 22 ankles: 4 stage 2 ankles, 5 stage 3a ankles, 6 stage 3b ankles, and 4 stage 4 ankles, categorized according to the Takakura-Tanaka classification. As the control group, 3 ankles without prior ankle injuries and disorders and 4 stage 2 ankles were included. One control ankle was used as a reference. Relative values compared with the reference ankle were evaluated in each group using Go-ICP. Each axis was set so that dorsiflexion, valgus, and abduction were positive on the X axis, Y axis, and Z axis, respectively. Results: Rotation angles of the talus (Rotation T) and calcaneus (Rotation C) on the Y axis in the control and stage 3b were −7.6, −28, −2.1, and −13 degrees, respectively, indicating significant differences. Value of Rotation T-Rotation C (Rotation T-C) represents compensatory function of the subtalar joint. In all ankles, there was a correlation between Rotation T and Rotation T-C on the Y axis and Z axis ( P < .01, r = 0.84; P < .01, r = −0.84, respectively). There was a correlation between Rotation T values on the on Y and Z axes ( P = .01, r = 0.53). Conclusion: In varus ankle osteoarthritis, the talus had varus deformity with adduction. Compensatory function in the coronal plane persisted, even in the advanced stages; however, it was not sufficiently maintained in stage 3b. Furthermore, compensatory function in the axial plane was relatively sustained. Level of Evidence: Level III, retrospective comparative study.
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Yang, Xue, Junchi Yan, Ziming Feng i Tao He. "R3Det: Refined Single-Stage Detector with Feature Refinement for Rotating Object". Proceedings of the AAAI Conference on Artificial Intelligence 35, nr 4 (18.05.2021): 3163–71. http://dx.doi.org/10.1609/aaai.v35i4.16426.
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Rotation detection is a challenging task due to the difficulties of locating the multi-angle objects and separating them effectively from the background. Though considerable progress has been made, for practical settings, there still exist challenges for rotating objects with large aspect ratio, dense distribution and category extremely imbalance. In this paper, we propose an end-to-end refined single-stage rotation detector for fast and accurate object detection by using a progressive regression approach from coarse to fine granularity. Considering the shortcoming of feature misalignment in existing refined single-stage detector, we design a feature refinement module to improve detection performance by getting more accurate features. The key idea of feature refinement module is to re-encode the position information of the current refined bounding box to the corresponding feature points through pixel-wise feature interpolation to realize feature reconstruction and alignment. For more accurate rotation estimation, an approximate SkewIoU loss is proposed to solve the problem that the calculation of SkewIoU is not derivable. Experiments on three popular remote sensing public datasets DOTA, HRSC2016, UCAS-AOD as well as one scene text dataset ICDAR2015 show the effectiveness of our approach. The source code is available at https://github.com/Thinklab-SJTU/R3Det_Tensorflow and is also integrated in our open source rotation detection benchmark: https://github.com/yangxue0827/RotationDetection.
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D'Alessandro, G., L. Mele, F. Columbro, G. Amico, E. S. Battistelli, P. de Bernardis, A. Coppolecchia i in. "QUBIC VI: Cryogenic half wave plate rotator, design and performance". Journal of Cosmology and Astroparticle Physics 2022, nr 04 (1.04.2022): 039. http://dx.doi.org/10.1088/1475-7516/2022/04/039.
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Abstract Setting an upper limit or detection of B-mode polarization imprinted by gravitational waves from Inflation is one goal of modern large angular scale cosmic microwave background (CMB) experiments around the world. A great effort is being made in the deployment of many ground-based, balloon-borne and satellite experiments, using different methods to separate this faint polarized component from the incoming radiation. QUBIC exploits one of the most widely-used techniques to extract the input Stokes parameters, consisting in a rotating half-wave plate (HWP) and a linear polarizer to separate and modulate polarization components. QUBIC uses a step-by-step rotating HWP, with 15° steps, combined with a 0.4°s-1 azimuth sky scan speed. The rotation is driven by a stepper motor mounted on the cryostat outer shell to avoid heat load at internal cryogenic stages. The design of this optical element is an engineering challenge due to its large 370 mm diameter and the 8 K operation temperature that are unique features of the QUBIC experiment. We present the design for a modulator mechanism for up to 370 mm, and the first optical tests by using the prototype of QUBIC HWP (180 mm diameter). The tests and results presented in this work show that the QUBIC HWP rotator can achieve a precision of 0.15° in position by using the stepper motor and custom-made optical encoder. The rotation induces <5.0 mW (95% C.L) of power load on the 4 K stage, resulting in no thermal issues on this stage during measurements. We measure a temperature settle-down characteristic time of 28 s after a rotation through a 15° step, compatible with the scanning strategy, and we estimate a maximum temperature gradient within the HWP of ≤ 10 mK. This was calculated by setting up finite element thermal simulations that include the temperature profiles measured during the rotator operations. We report polarization modulation measurements performed at 150 GHz, showing a polarization efficiency >99% (68% C.L.) and a median cross-polarization χPol of 0.12%, with 71% of detectors showing a χPol + 2σ upper limit <1%, measured using selected detectors that had the best signal-to-noise ratio.
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Malael, I., i V. Dragan. "Numerical and Experimental Efficiency Evaluation of a Counter-Rotating Vertical Axis Wind Turbine". Engineering, Technology & Applied Science Research 8, nr 4 (18.08.2018): 3282–86. http://dx.doi.org/10.48084/etasr.2231.
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This paper investigates the concept of a concentric counter-rotating vertical axis wind turbine (VAWT), consisting of a two stage vertical H-type turbine with three blades on each stage. The model has an inner and an outer stage, rotating in opposition to each other. Both numerical and experimental tests have been performed in order to validate this new concept. Numerical analysis is based on the use of 2.5-dimensional, unsteady simulations using a DOF type of analysis which allows for the two stages to self-adjust their rotation speed. Sliding mesh conformal interfaces are defined between these subdomains to minimize numerical artifacts such as artificial relations or entropy changes. Fully turbulent URANS were carried out in Ansys Fluent software. One key outcome was the momentum coefficient for each stage at different tip wind speed values. Another, more qualitative, outcome is the analysis of vortex shedding, impingement and overall interaction between the stages at different positions and scenarios. Ultimately, the numerical results have been validated using a scaled experimental device which was analyzed in the wind tunnel at different free stream speeds.
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Ebus, Tobias, Markus Dietz i Andreas Hupfer. "Experimental and numerical studies on small contra-rotating electrical ducted fan engines". CEAS Aeronautical Journal 12, nr 3 (29.05.2021): 559–71. http://dx.doi.org/10.1007/s13272-021-00517-7.
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AbstractElectrical propulsion has been identified as one of the key fields of future research within the aerospace sector. The Institute of Aeronautical Engineering at the Universität der Bundeswehr München aims to contribute to the ongoing development of small-sized electrical ducted fan engines with a thrust in the range of 100 N. A special emphasis is placed on electrically powered contra-rotating fan stages. When compared to a conventional rotor–stator stage, contra-rotating fan stages allow for a more compact design, considering a given pressure ratio, or an increased pressure ratio at a constant fan diameter. Since numerous new aircraft concepts are presently being developed, a high demand for compact and powerful electrically driven engines arises. Electrically driven contra-rotating fan engines provide a high potential in terms of compactness, emissions and efficiency. Using electric motors offers the ability to overcome common issues, such as design and integration of a contra-rotating stage into a gas turbine. An innovative new engine design featuring such a contra-rotating stage is developed and tested at one of the Institute’s test benches for electrical propulsion. Key components are two brushless motors powering the fan stage, one for each rotor. Various operation points are investigated experimentally during an extensive test campaign. Experimental results are compared to results of numerical simulations computed by ANSYS CFX. Results indicate a good agreement between experiment and simulation. The engine is running very smooth throughout all tested operation points. Yet, intensive heating up of the electric motors and high-temperature zone are found to be an issue at higher rotation speeds.
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Tuszynski, Jack A., i Richard Gordon. "A mean field Ising model for cortical rotation in amphibian one-cell stage embryos". Biosystems 109, nr 3 (wrzesień 2012): 381–89. http://dx.doi.org/10.1016/j.biosystems.2012.05.007.
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Stoneham, E., L. Witt, Q. Paterson, L. Martin i B. Thoma. "P101: The development of entrustable professional activity reference cards to support the implementation of Competence by Design in emergency medicine". CJEM 21, S1 (maj 2019): S100. http://dx.doi.org/10.1017/cem.2019.292.
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Innovation Concept: Competence by Design (CBD) was implemented nationally for Emergency Medicine (EM) residents beginning training in 2018. One challenge is the need to introduce residents to Entrustable Professional Activities (EPAs) that are assessed across numerous clinical rotations. The Royal College's resources detail these requirements, but do not map them to specific rotations or present them in a succinct format. This is problematic as trainees are less likely to succeed when expectations are unclear. We identified a need to create practical resources that residents can use at the bedside. Methods: We followed an intervention mapping framework to design two practical, user-friendly, low-cost, aesthetically pleasing resources that could be used by residents and observers at the bedside to facilitate competency-based assessment. Curriculum, Tool or Material: First, we designed a set of rotation- and stage-specific EPA reference cards for the use of residents and observers at the bedside. These cards list EPAs and clinical presentations likely to be encountered during various stages of training and on certain rotations. Second, we developed a curriculum board to organize the EPA reference cards by stage based upon our program's curriculum map. The curriculum board allows residents to view the program's curriculum map and the EPAs associated with each clinical rotation at a glance. It also contains hooks to hang and store extra cards in an organized manner. Conclusion: We believe that these practical and inexpensive tools facilitated our residency program's transition to competency-based EPA assessments. Anecdotally, the residents are using the cards and completing the suggested rotation-specific EPAs. We hope that the reference cards and curriculum board will be successfully incorporated into other residency programs to facilitate the introduction of their EPA-based CBD assessment system.
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Soni, Krupa M., Urmi Bhatt i Vidhya Solanki. "Patterns of Range of Motion Restriction in Subjects with Adhesive Capsulitis". International Journal of Health Sciences and Research 11, nr 6 (22.06.2021): 337–41. http://dx.doi.org/10.52403/ijhsr.20210650.
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Background: Adhesive capsulitis is one of the most common problems of the arm. It is a painful and disabling condition and the etiology is unclear. Adhesive capsulitis is caused by tightening of the joint capsule and results in stiffness and pain. Adhesive capsulitis occurs in three distinct stages. Freezing stage, Frozen stage & Thawing stage. Till date, adhesive capsulitis remains to be more of a clinical diagnosis rather than radiological. Cyriax’s proposed shoulder capsular pattern was external rotation most limited followed by abduction followed by internal rotation. It remains unclear whether this pattern is exists in all the phases of adhesive capsulitis or not. Aim: To identify pattern of restriction of ROM in subjects with adhesive capsulitis in three phases of adhesive capsulitis. Methodology: The study included 60 subjects with idiopathic adhesive capsulitis. Passive ROM for shoulder Abduction, internal and external rotation was measured with universal Goniometer. Results & Conclusion: Findings suggest that various patterns of restrictions were found in different phase of Adhesive capsulitis. Key words: Adhesive capsulitis, Shoulder passive ROM, Pattern of restriction.
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Choi, Kee-Bong, Jaejong Lee, Geehong Kim, Hyungjun Lim i Soongeun Kwon. "Kinematic Analysis of a Parallel Manipulator Driven by Perpendicular Linear Actuators". Actuators 10, nr 10 (9.10.2021): 262. http://dx.doi.org/10.3390/act10100262.
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In this paper, a goniometer-type specimen stage with a linear actuation mechanism mounted on a rotation mechanism is introduced. The linear actuation mechanism was modeled as a spatial parallel manipulator consisting of a moving body, three linear actuators, and an anti-rotation mechanism. The three linear actuators were arranged perpendicular to each other. In the specimen stage, the linear actuators were in ball contact with the surface of a holder designed to hold a specimen. For the parallel manipulator, the ball contact was replaced with two prismatic joints and a spherical joint. The mobility of the manipulator without the anti-rotation mechanism was one degree of freedom greater than the number of actuators. Therefore, the redundant one degree-of-freedom motion was restrained using an anti-rotation mechanism with three rotation joints and two prismatic joints. The inverse and direct kinematics of the goniometer mechanism were derived and verified. In addition, the inverse Jacobian was derived, and local and global performance indices were analyzed by the terms of manipulability and isotropy. Finally, the goniometer-type specimen stage was designed by the global performance indices.
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Dittmann, M., K. Dullenkopf i S. Wittig. "Direct-Transfer Preswirl System: A One-Dimensional Modular Characterization of the Flow". Journal of Engineering for Gas Turbines and Power 127, nr 2 (1.04.2005): 383–88. http://dx.doi.org/10.1115/1.1787514.
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In high-efficiency gas turbine engines, the cooling air for the high-pressure turbine stage is expanded through stationary preswirl nozzles, transferred through the preswirl chamber, and delivered to the blade feed holes of the rotor. By accelerating the cooling air in the direction of rotation, the total temperature relative to the rotor disk and the pressure losses occurring at the receiver hole inlet can be reduced. The discharge behavior of a direct-transfer preswirl system has been investigated experimentally for different number of receiver holes and different inlet geometries, varying axial gap widths between stator and rotor and for rotational Reynolds numbers up to Reϕ=2.3×10 6. The discharge coefficients of the preswirl nozzles are given in the absolute frame of reference while the definition of the discharge coefficients of the receiver holes is applied to the rotating system in order to consider the work done by the rotor. A momentum balance is used to evaluate the deflection of the preswirled air entering the receiver holes. The flow in the preswirl chamber is characterized by introducing an effective velocity of the cooling air upstream of the rotor disk. The influences of geometrical parameters and operating points are reported and discussed in this paper.
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Wei, Zhicong, Wei Yang i Ruofu Xiao. "Pressure Fluctuation and Flow Characteristics in a Two-Stage Double-Suction Centrifugal Pump". Symmetry 11, nr 1 (8.01.2019): 65. http://dx.doi.org/10.3390/sym11010065.
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Pressure fluctuation is the primary factor that affects the stability of turbomachines. The goal of the present work is to explore the propagation of pressure fluctuations in a two-stage double-suction centrifugal pump. The pressure fluctuation characteristics of each component of a two-stage double-suction centrifugal pump are simulated under four typical flow rates based on the SST k-ω turbulence model. It is shown that the pressure fluctuation frequency at blade passing frequency and its first harmonic is the same at the suction chamber, the leading edge, and the middle of the first-stage impeller, which is different from the rotor–stator interaction. Moreover, the uneven impeller inlet flow distribution will produce fluctuations with rotation frequency and its harmonics at the leading edge of the impellers in both stages. Finally, broadband frequency is found at the trailing edge of the impellers in both stages associated with the first harmonic of the rotation frequency, especially under the part load condition. The large size backflow vortex appears in the blade flow channel leading to the low-pressure zone between the impeller, the tongue, and the start of the partition. That is why the pressure drops significantly twice in one rotation period when the blades pass through the tongue and the start of the partition.
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Smith, Robert Connon. "The Evolution of Rapidly Rotating B Stars (Review Paper)". International Astronomical Union Colloquium 92 (sierpień 1987): 486–99. http://dx.doi.org/10.1017/s0252921100116665.
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AbstractBe stars are located in or near the main-sequence band for non-rotating stars. Although this stage of evolution is relatively well understood, there are two main effects that make it impossible to say whether all Be stars are in the same stage of evolution and, if so, what that stage is. One effect is the spread in observed magnitude and colour as a result of rotation. Correction for rotation is not possible because of the unknown inclination of any particular star's rotation axis to the line of sight and because it is not clear what the internal angular momentum distribution is or how it changes as a result of evolution. The other effect is that there are uncertainties in the theoretical evolutionary tracks because the amount of convective overshooting is unclear. Other mixing mechanisms that might in principle also confuse the tracks seem to be small near the main sequence. If Be stars are related to the β Cephei and 53 Persei stars in the same part of the HR diagram, then the non-radial pulsation properties of Be stars may give a clue to their evolutionary state. The existence of a circumstellar disc or ring, however, tells us very little about the evolutionary stage of the underlying star. A useful way forward may be to try to understand individual stars in as much detail as possible.
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Lander, S. K., P. Haensel, B. Haskell, J. L. Zdunik i M. Fortin. "Magnetic fields in late-stage proto-neutron stars". Monthly Notices of the Royal Astronomical Society 503, nr 1 (17.02.2021): 875–95. http://dx.doi.org/10.1093/mnras/stab460.
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ABSTRACT We explore the thermal and magnetic field structure of a late-stage proto-neutron star (proto-NS). We find the dominant contribution to the entropy in different regions of the star, from which we build a simplified equation of state (EOS) for the hot neutron star (NS). With this, we numerically solve the stellar equilibrium equations to find a range of models, including magnetic fields and rotation up to Keplerian velocity. We approximate the EOS as a barotrope, and discuss the validity of this assumption. For fixed magnetic field strength, the induced ellipticity increases with temperature; we give quantitative formulae for this. The Keplerian velocity is considerably lower for hotter stars, which may set a de facto maximum rotation rate for non-recycled NSs well below 1 kHz. Magnetic fields stronger than around 1014 G have qualitatively similar equilibrium states in both hot and cold NSs, with large-scale simple structure and the poloidal field component dominating over the toroidal one; we argue this result may be universal. We show that truncating magnetic field solutions at low multipoles leads to serious inaccuracies, especially for models with rapid rotation or a strong toroidal-field component.
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Konstantinova–Antova, Renada K. "Rotation, Convection, Activity and Lithium in Single G and K giants". Symposium - International Astronomical Union 215 (2004): 287–88. http://dx.doi.org/10.1017/s0074180900195737.
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We studied the activity and evolutionary stage of 14 low and intermediate mass single giants that should meet the conditions for dynamo action and Li–enrichment. Only small part of them exhibit either moderate to fast rotation and evidences for magnetic activity and/or high Li abundance. There are also intermediate–mass giants with fast rotation, but no evidences for magnetic activity was found in them and their Li–content is low one. on the other hand, no fast rotation and activity were observed in some of the Li–rich giants. There is a large difference in the activity properties and Li content in stars with similar masses and evolutionary stage.
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Wahyudi, Irfan, Isaac Ardianson Deswanto, Gerhard Reinaldi Situmorang i Arry Rodjani. "One stage rotation flap scrotoplasty and orchidopexy for the correction of ectopic scrotum: A case report". Urology Case Reports 25 (lipiec 2019): 100886. http://dx.doi.org/10.1016/j.eucr.2019.100886.
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Pattabirani, G., i K. Selvakumar. "Implementation of Energy HEED (ER-HEED) Protocol Using Super Cluster Head for WSN". Asian Journal of Computer Science and Technology 7, S1 (5.11.2018): 119–22. http://dx.doi.org/10.51983/ajcst-2018.7.s1.1790.
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Wireless Sensor Network (WSN) is used in almost all applications in developing environment. This is due to their ability and easy implementation through several applications. The most important criteria in WSN are to minimize the energy consumption and improve the network lifetime. Clustering algorithms are considered as one of the effective way to improve the network lifetime in WSN. Hybrid, Energy-Efficient and Distributed (HEED) clustering approach uses energy-efficient clustering algorithm. This paper proposes an Enhanced Rotational HEED (ER-HEED) protocol using super cluster head for minimizing energy consumption and to improve the network lifetime. The proposed work is carried out in two stages, first stage, super cluster head is introduced. In second stage, the node with maximum threshold is chosen as a cluster head on rotation within in the cluster. The results show that the ER-HEED performs well when compared with HEED and LEACH.
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Ardeljan, N. V., G. S. Bisnovatyi-Kogan i S. G. Moiseenko. "Magnetorotational Mechanism: Supernova Explosions and Ejections". Symposium - International Astronomical Union 214 (2003): 117–20. http://dx.doi.org/10.1017/s0074180900194252.
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We made simulations of the collapse of the rotating protostellar cloud. Differential rotation leads to the amplification of the toroidal component of the magnetic field and subsequent ejection of the matter due to the magnetorotational mechanism.Our results show that at different initial configurations of the magnetic field formation of qualitatively different types of explosion takes place. Magnetic field of the dipole type produces a jet-like explosion. Quadrupole-like magnetic field produces supernova explosion whith ejection presumably near equatorial plane. Quantitative estimations of the ejected mass and energy are given.We have done simulation of the collapse of the white dwarf and formation of a differentially rotating neutron star. After the collapse stage the rotating neutron star was formed. The rotation of the neutron star is strongly differential. The presence of the magnetic field (even the weak one) could produce magnetorotational supernova explosion.For the simulations we have used 2D numerical scheme, based on the specially developed numerical method (conservative, implicit, triangular grid, Lagrangian, grid reconstruction).
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Dong, Qingming, i Amalendu Sau. "Unsteady electrorotation of a viscous drop in a uniform electric field". Physics of Fluids 35, nr 4 (kwiecień 2023): 047116. http://dx.doi.org/10.1063/5.0140845.
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A dielectric drop suspended in an immiscible dielectric fluid of higher conductivity can spontaneously generate the so-called Quincke rotation (a rotating activity that a weakly conducting drop/solid particle displays in an electric field) subjected to sufficiently strong electric field strength. The steady tilt has been extensively studied and is well elucidated now. However, the unsteady electrorotation of drop remains a largely unclear, complex issue. Motivated by this, we examine the unsteady drop electrorotation in this work with the required integrated convective bulk charge transport effect. First, for the steady rotation, the transient evolution to a steady droplet tilt from the symmetric Taylor state is analyzed in-depth. Here we discover several new phenomena, including the evolving equatorial charge jets. For unsteady rotation, based on a drop's interfacial charge variation, deformation, and tilt angle, the study reports the growth of three distinct rotating patterns in the viscosity ratio range [Formula: see text] and electric field strength [Formula: see text] at a fixed conductivity ratio Q ( = [Formula: see text]) = 0.026 and permittivity ratio S (=[Formula: see text]) = 0.566. A low-viscosity drop ([Formula: see text]) exhibits only the periodic rotation. For the viscosity ratio [Formula: see text], the increased electric intensity creates two new unsteady rotation modes: the pseudo-periodic tumbling and the irregular one. For [Formula: see text], the periodic mode remains absent; instead, the drop displays the electric intensity-dependent tumbling and irregular rotation patterns. Our study shows that the rotation reduces a drop's transitory interfacial charge. At this stage, the drop rotation behavior is controlled by competing charge convection due to fluid flow and charge supply by conduction. The resulting varying electric Reynolds number [Formula: see text] (the time ratio of charge relaxation and charge convection) explains the created different rotation mechanisms. For [Formula: see text], owing to lacking enough interfacial charge to sustain rotation, the drop's transition to a temporary non-rotating Taylor state occurs until the interface recharges. The resultant mechanism supports the periodic batch-type rotation for a low-viscosity drop and the irregular rotation for a high-viscosity drop in a higher electric field. In contrast, for [Formula: see text], the drop timely acquires sufficient charge to support continuous tumbling electrorotation.
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Mosley, Caroline, John R. Mosley, Catriona Bell, Kay Aitchison, Susan M. Rhind i Jill MacKay. "Teaching best practice in hand hygiene: student use and performance with a gamified gesture recognition system". Veterinary Record 185, nr 14 (23.08.2019): 444. http://dx.doi.org/10.1136/vr.105338.
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The use of an automated gesture recognition system to teach the commonly adopted, seven-stage hand hygiene technique to veterinary undergraduate students was evaluated. The system features moderate gamification, intended to motivate the student to use the machine repeatedly. The system records each handwash stage, and those found to be difficult are identified and reported back. The gamification element alone was not sufficient to encourage repeated use of the machine, with only 13.6 per cent of 611 eligible students interacting with the machine on one or more occasion. Overall engagement remained low (mean sessions per user: 3.5, ±0.60 confidence interval), even following recruitment of infection control ambassadors who were given a specific remit to encourage engagement with the system. Compliance monitoring was introduced to explore how students used the system. Hand hygiene performance did not improve with repeated use. There was evidence that the stages—fingers interlaced, rotation of the thumb, rotation of the fingertips and rotation of the wrists—were more challenging for students to master (p=0.0197 to p<0.0001) than the back of the hand and of the fingers. Veterinary schools wishing to use such a system should consider adopting approaches that encourage peer buy-in, and highlight the ability to practise difficult stages of the technique.
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Qian, Wen, Xue Yang, Silong Peng, Junchi Yan i Yue Guo. "Learning Modulated Loss for Rotated Object Detection". Proceedings of the AAAI Conference on Artificial Intelligence 35, nr 3 (18.05.2021): 2458–66. http://dx.doi.org/10.1609/aaai.v35i3.16347.
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Popular rotated detection methods usually use five parameters (coordinates of the central point, width, height, and rotation angle) or eight parameters (coordinates of four vertices) to describe the rotated bounding box and l1 loss as the loss function. In this paper, we argue that the aforementioned integration can cause training instability and performance degeneration. The main reason is the discontinuity of loss which is caused by the contradiction between the definition of the rotated bounding box and the loss function. We refer to the above issues as rotation sensitivity error (RSE) and propose a modulated rotation loss to dismiss the discontinuity of loss. The modulated rotation loss can achieve consistent improvement on the five parameter methods and the eight parameter methods. Experimental results using one stage and two stages detectors demonstrate the effectiveness of our loss. The integrated network achieves competitive performances on several benchmarks including DOTA and UCAS AOD. The code is available at https://github.com/yangxue0827/RotationDetection.
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Song, H. F., G. Meynet, A. Maeder, S. Ekström, P. Eggenberger, C. Georgy, Y. Qin i in. "Close binary evolution". Astronomy & Astrophysics 609 (22.12.2017): A3. http://dx.doi.org/10.1051/0004-6361/201731073.
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Context. Massive stars with solar metallicity lose important amounts of rotational angular momentum through their winds. When a magnetic field is present at the surface of a star, efficient angular momentum losses can still be achieved even when the mass-loss rate is very modest, at lower metallicities, or for lower-initial-mass stars. In a close binary system, the effect of wind magnetic braking also interacts with the influence of tides, resulting in a complex evolution of rotation. Aims. We study the interactions between the process of wind magnetic braking and tides in close binary systems. Methods. We discuss the evolution of a 10 M⊙ star in a close binary system with a 7 M⊙ companion using the Geneva stellar evolution code. The initial orbital period is 1.2 days. The 10 M⊙ star has a surface magnetic field of 1 kG. Various initial rotations are considered. We use two different approaches for the internal angular momentum transport. In one of them, angular momentum is transported by shear and meridional currents. In the other, a strong internal magnetic field imposes nearly perfect solid-body rotation. The evolution of the primary is computed until the first mass-transfer episode occurs. The cases of different values for the magnetic fields and for various orbital periods and mass ratios are briefly discussed. Results. We show that, independently of the initial rotation rate of the primary and the efficiency of the internal angular momentum transport, the surface rotation of the primary will converge, in a time that is short with respect to the main-sequence lifetime, towards a slowly evolving velocity that is different from the synchronization velocity. This “equilibrium angular velocity” is always inferior to the angular orbital velocity. In a given close binary system at this equilibrium stage, the difference between the spin and the orbital angular velocities becomes larger when the mass losses and/or the surface magnetic field increase. The treatment of the internal angular momentum transport has a strong impact on the evolutionary tracks in the Hertzsprung-Russell Diagram as well as on the changes of the surface abundances resulting from rotational mixing. Our modelling suggests that the presence of an undetected close companion might explain rapidly rotating stars with strong surface magnetic fields, having ages well above the magnetic braking timescale. Our models predict that the rotation of most stars of this type increases as a function of time, except for a first initial phase in spin-down systems. The measure of their surface abundances, together, when possible, with their mass-luminosity ratio, provide interesting constraints on the transport efficiencies of angular momentum and chemical species. Conclusions. Close binaries, when studied at phases predating any mass transfer, are key objects to probe the physics of rotation and magnetic fields in stars.
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Nakamura, Shuichi, i Hotaka Homma. "Micro-Scale OIM Study on the Recrystallization Process of Cold Rolled α-Fiber Single Crystal". Materials Science Forum 467-470 (październik 2004): 159–64. http://dx.doi.org/10.4028/www.scientific.net/msf.467-470.159.
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Recrystallization of cold rolled {211}<011> single crystal of 3.5%Si-Fe were investigated by electron back-scattered pattern (EBSP) technique in order to clarify the formation of {h,1,1}<1/h, 1, 2> fiber in recrystallization texture of steel with high cold rolling reduction. In the cold rolled sample, there exist shearband like substructures characterized by the orientation fluctuation with single <011> axis whereas their orientations are almost kept to the original orientation {211}<011> which belongs to a-fiber (RD//<110> fiber). In the recovery stage, the orientation fluctuations are enhanced and include fluctuations with another <011> axis. That is the fluctuations in recovery stage are not characterized by rotation relationship with single <011> axis. The recrystallization texture includes {100}<012> and {411}<148> as major orientations in {h,1,1}<1/h, 1, 2> fiber. Furthermore, there exists clear orientation relationship characterized by multiple rotations with <011> axes between the recrystallization orientations and the original one. Actually, orientations characterized by rotational relationships with <211> (=[110]+[101]) axis and <111> (=[110]+[101]+[011]) were observed. These results suggest that recrystallization from a-fiber is occurred as a result of the final enhanced stage of the fluctuations characterized by multiple rotations with <011> axes.
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Zhang, Zhen-Wei, Zheng Li, Ying Liu i Jing-Tao Wang. "Path Dependency of Plastic Deformation in Crystals: Work Hardening, Crystallographic Rotation and Dislocation Structure Evolution". Crystals 12, nr 7 (19.07.2022): 999. http://dx.doi.org/10.3390/cryst12070999.
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This paper reviewed the research progress of studies on the crystal rotation of single crystals that were deformed by tension and shear and the influences of crystal rotation and dislocation evolution on strain hardening behavior in crystals that were deformed with different initial orientations. The crystal rotation is entirely different depending on whether the single crystal was deformed by tension or shear. A three-stage work hardening behavior, which is not one of the intrinsic properties of materials, is generated when FCC metallic single crystals are deformed by tension along unstable oriFigurFigurentations, but single crystals do not exhibit this three-stage hardening behavior when they are deformed by simple shear at room temperature. Under tension, crystal rotation causes the transition from work hardening stage I to stage II, while the transition from work hardening stage II to III is caused by dislocation evolution. The evolution of the dislocation structure is related to deformation loading and can be classified into three types when a crystal is deformed by tension. Different from tension, shear stress can directly act on one of the 12 slip systems when a crystal is deformed by simple shear. When FCC single crystals are deformed by shear along the (11¯1)[110], (111)[112¯] and (001)[110] orientations, the single slip system, co-planar slip systems and co-directional slip systems are activated, respectively, and the crystals hardly rotate under the shear conditions. The slip direction of [110] forces the crystal to rotate toward the shear direction under simple shear. The dislocation tangles tend to form the dislocation cells and wall structures when multiple slip systems are activated under simple shear.
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Bibikov, Petr, Larisa Petrova, Irina Belashova i Peter Demin. "Surface Strengthening of High-Alloyed Martensitic Steel by Staged Nitriding". MATEC Web of Conferences 346 (2021): 02035. http://dx.doi.org/10.1051/matecconf/202134602035.
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Gas nitriding processes with cyclical rotation of ammonia and ammonia/air atmospheres are suggested for surface strengthening of martensitic Cr-Ni-W-Mo-V steel. One-, two-, and three-staged processes were studied differing by gas atmospheres at the final stage of processes. Microstructure and phase composition of received diffusion layers were examined. Results of microhardness, wear and impact toughness tests are discussed in correspondence with the layers structure.
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Kholid, Ismail, i Mohammad Alexin Putra. "THE EFFECT OF THE NUMBER OF HORIZONTAL WIND TURBINE ON PERFORMANCE IN MICRO-SCALE POWER PLANT". Barometer 7, nr 2 (31.07.2022): 95–106. http://dx.doi.org/10.35261/barometer.v7i2.6663.
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Wind power plant is a power plant that uses renewable energy, namely wind energy. This study tested micro-scale wind power plants using a horizontal type wind turbine with a diameter of one meter with variations in the number of blades, namely 16 blades, 14 blades, 12 blades and 10 blades at wind speeds of 4.7 m/s, 4.1 m/s. , 3.6 m/s and 3 m/s. The purpose of this study was to determine the effect of the number of horizontal wind turbine blades on the turbine rotation with the load and electrical power generated. This research uses an experimental method and is divided into 3 stages, the first stage is the design of research tools and components, the second stage is making research tools and components, the third stage is testing. Based on the results of testing using a load, a wind turbine with 16 blades produces the highest turbine rotation, which is 47 rpm at a wind speed of 4.7 m/s and produces the highest electrical power, which is 0.12 W at a wind speed of 4.7 m/s.
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Chen, Yushan, Wenbin Xu, Liang Jiang i Linmao Qian. "Scanning probe microscope probe switching unit with electrical measurement for in situ multifunctional characterization: Design and preliminary application in tribocorrosion investigation". Journal of Applied Physics 132, nr 10 (14.09.2022): 105303. http://dx.doi.org/10.1063/5.0105596.
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Scanning probe microscope (SPM) is a potent tool in nanotribology research. However, commercial environment control SPMs can install only one probe to perform one function at a time. Accordingly, this study developed a probe switching unit with electrical measurement for in situ multifunctional characterization. The unit mainly comprises a cover, a rotation stage, and a probe holder assembly. Four probes can be installed. One is electrically connected to perform tapping mode and electrical measurement such as Kelvin probe force microscope (0.01 mV resolution), while the other three are to perform contact mode. The rotation stage drives the assembly to switch probes to in situ measure multiple physical quantities in a controlled environment. The unit was preliminarily applied to investigate tantalum tribocorrosion. Based on the changing trends of wear amount and surface potential change, the wear process can be roughly divided into three stages, which may be caused by desorption of the adsorbed air, wear of the oxide film, and wear of the substrate, respectively. Moreover, wear can lead to a surface potential increment, which may partly contribute to the galvanic corrosion between the virgin area and the wear area. The unit may serve as a useful tool for nanotribology research.
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Zhang, Liu, Zongming Liu, Dong Ye i Guanyu Zhang. "Relative Attitude Estimation for a Uniform Motion and Slowly Rotating Noncooperative Spacecraft". Mathematical Problems in Engineering 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/1787530.
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This paper presents a novel relative attitude estimation approach for a uniform motion and slowly rotating noncooperative spacecraft. It is assumed that the uniform motion and slowly rotating noncooperative chief spacecraft is in failure or out of control and there is no a priori rotation rate information. We utilize a very fast binary descriptor based on binary robust independent elementary features (BRIEF) to obtain the features of the target, which are rotational invariance and resistance to noise. And then, we propose a novel combination of single candidate random sample consensus (RANSAC) with extended Kalman filter (EKF) that makes use of the available prior probabilistic information from the EKF in the RANSAC model hypothesis stage. The advantage of this combination obviously reduces the sample size to only one, which results in large computational savings without the loss of accuracy. Experimental results from real image sequence of a real model target show that the relative angular error is about 3.5% and the mean angular velocity error is about 0.1 deg/s.
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Brokešová, Johana, Jiří Málek, Jiří Vackář, Felix Bernauer, Joachim Wassermann i Heiner Igel. "Rotaphone-CY: The Newest Rotaphone Model Design and Preliminary Results from Performance Tests with Active Seismic Sources". Sensors 21, nr 2 (14.01.2021): 562. http://dx.doi.org/10.3390/s21020562.
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Rotaphone-CY is a six-component short-period seismograph that is capable of the co-located recording of three translational (ground velocity) components along three orthogonal axes and three rotational (rotation rate) components around the three axes in one device. It is a mechanical sensor system utilizing records from elemental sensors (geophones) arranged in parallel pairs to derive differential motions in the pairs. The pairs are attached to a rigid frame that is anchored to the ground. The model design, the latest one among various Rotaphone designs based on the same principle and presented elsewhere, is briefly introduced. The upgrades of the new model are a 32-bit A/D converter, a more precise placing of the geophones to parallel pairs and a better housing, which protects the instrument from external electromagnetic noise. The instrument is still in a developmental stage. It was tested in a field experiment that took place at the Geophysical Observatory in Fürstenfeldbruck (Germany) in November 2019. Four Rotaphones-CY underwent the huddle-testing phase of the experiment as well as the field-deployment phase, in which the instruments were installed in a small-aperture seismic array of a triangular shape. The preliminary results from this active-source experiment are shown. Rotaphone-CY data are verified, in part, by various approaches: mutual comparison of records from four independent Rotaphone-CY instruments, waveform matching according to rotation-to-translation relations, and comparison to array-derived rotations when applicable. The preliminary results are very promising and they suggest the good functionality of the Rotaphone-CY design. It has been proved that the present Rotaphone-CY model is a reliable instrument for measuring short-period seismic rotations of the amplitudes as small as 10−7 rad/s.
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Yang, Dengfeng, Ce Yang, Dazhong Lao i Tao Zeng. "A detailed investigation of a variable nozzle turbine with novel forepart rotation guide vane". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, nr 4 (25.02.2018): 994–1007. http://dx.doi.org/10.1177/0954407018757244.
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One of the disadvantages of a variable nozzle turbine in practical application is the stage performance degradation due to nozzle endwall leakage flow at small nozzle openings. Aiming at restricting the nozzle leakage flow rate to improve turbine stage performance, a novel forepart rotation guide vane has been proposed and numerically studied in present work. First, the numerical results of baseline turbine were validated by experimental data to ensure the accuracy of numerical methods. Then steady and unsteady simulations were performed on both baseline and forepart rotation guide vane turbines to demonstrate the effectiveness of the novel vane and to study the characteristics of nozzle leakage flow, respectively. Results indicate that there is up to 13.5% peak efficiency improvement that has been achieved at 10% nozzle opening with the forepart rotation guide vane design; besides, rotor–stator interaction for forepart rotation guide vane is also mitigated due to the reduced nozzle leakage flow rate, thus the intensity of loading fluctuation on rotor blades is weakened significantly, which is beneficial to improve rotor blade forced response.
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Ding, Bingxiao, Yangmin Li, Xiao Xiao, Yirui Tang i Bin Li. "Design and analysis of a 3-DOF planar micromanipulation stage with large rotational displacement for micromanipulation system". Mechanical Sciences 8, nr 1 (23.05.2017): 117–26. http://dx.doi.org/10.5194/ms-8-117-2017.
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Abstract. Flexure-based mechanisms have been widely used for scanning tunneling microscopy, nanoimprint lithography, fast servo tool system and micro/nano manipulation. In this paper, a novel planar micromanipulation stage with large rotational displacement is proposed. The designed monolithic manipulator has three degrees of freedom (DOF), i.e. two translations along the X and Y axes and one rotation around Z axis. In order to get a large workspace, the lever mechanism is adopted to magnify the stroke of the piezoelectric actuators and also the leaf beam flexure is utilized due to its large rotational scope. Different from conventional pre-tightening mechanism, a modified pre-tightening mechanism, which is less harmful to the stacked actuators, is proposed in this paper. Taking the circular flexure hinges and leaf beam flexures hinges as revolute joints, the forward kinematics and inverse kinematics models of this stage are derived. The workspace of the micromanipulator is finally obtained, which is based on the derived kinematic models.
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Prokudin, A. N., i S. V. Firsov. "Elastoplastic deformation of a rotating hollow cylinder with a rigid casing". PNRPU Mechanics Bulletin, nr 4 (15.12.2019): 120–35. http://dx.doi.org/10.15593/perm.mech/2019.4.12.
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A rotating hollow cylinder with fixed ends is considered, the inner surface of which is free of stresses, and the outer one is fixed from radial movements. It is assumed that the cylinder is made of an ideal isotropic elastoplastic material, and the deformations in it are small and represent the sum of elastic and plastic deformations. Stresses are associated with elastic deformations by Hooke's law. Plastic deformations are determined using the Tresca - Saint-Venant condition and the plastic flow rule associated with it. The cylinder rotation speed first monotonically increases to a maximum value, and then decreases to zero. By using the elastic solution, the dependence is found for the critical rotation speed at which the plastic flow begins. It is established that, depending on the thickness of the cylinder and the Poisson's ratio, plastic flow can begin, either on the inner or on the outer surface of the cylinder. In addition, 3 plastic regions appear in the cylinder at the loading stage, and 4 plastic regions appear at the unloading stage. These regions correspond to two faces and two edges of the Treska prism. For each plastic region, an exact analytical solution of the determining system of equations is found. The system of conditions at the boundaries between the regions providing continuity of the obtained solutions throughout the cylinder is given. Two cases are considered, i.e. the case with a plastic flow which starts first on the inner, and then on the outer surface of the cylinder. Analytical expressions are obtained for rotational speeds at which new regions appear. The relationship between the nucleation rates of the secondary and primary plastic flow is established. The value of the maximum rotation speed sufficient for a complete transition of the cylinder to the state of the secondary plastic flow was also found. It has been revealed that the adding of a rigid casing can significantly increase the resource of an exploited part.
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Li, Wen Ya, Min Yu, Jing Long Li i Da Lu Gao. "Explicit Finite Element Analysis of the Plunge Stage of Tool in Friction Stir Welding". Materials Science Forum 620-622 (kwiecień 2009): 233–36. http://dx.doi.org/10.4028/www.scientific.net/msf.620-622.233.
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The investigation of the plunge stage of the tool during friction stir welding (FSW) is the basis of understanding the nature of FSW, which is especially important for friction stir spot welding. In this study, the plunge stage of FSW tool was numerically examined by dynamic explicit finite element method with more attention to the temperature evolution. It was found that the high temperature region around the stirred zone extended with increasing the rotation speed. The heat affected zone expanded with the increase of inserting time, but the highest temperature around the stirred zone changed little. The range of the stirred zone changed little with the variations of the rotation speed and inserting time. The simulation result on the temperature field was in comparable agreement with the experimental one.
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Salhi, Abdelaziz, Amor Khlifi i Claude Cambon. "Nonlinear Effects on the Precessional Instability in Magnetized Turbulence". Atmosphere 11, nr 1 (22.12.2019): 14. http://dx.doi.org/10.3390/atmos11010014.
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By means of direct numerical simulations (DNS), we study the impact of an imposed uniform magnetic field on precessing magnetohydrodynamic homogeneous turbulence with a unit magnetic Prandtl number. The base flow which can trigger the precessional instability consists of the superposition of a solid-body rotation around the vertical ( x 3 ) axis (with rate Ω ) and a plane shear (with rate S = 2 ε Ω ) viewed in a frame rotating (with rate Ω p = ε Ω ) about an axis normal to the plane of shear and to the solid-body rotation axis and under an imposed magnetic field that aligns with the solid-body rotation axis ( B ‖ Ω ) . While rotation rate and Poincaré number are fixed, Ω = 20 and ε = 0.17 , the B intensity was varied, B = 0.1 , 0.5 , and 2.5 , so that the Elsasser number is about Λ = 0.1 , 2.5 and 62.5 , respectively. At the final computational dimensionless time, S t = 2 ε Ω t = 67 , the Rossby number Ro is about 0.1 characterizing rapidly rotating flow. It is shown that the total (kinetic + magnetic) energy ( E ) , production rate ( P ) due the basic flow and dissipation rate ( D ) occur in two main phases associated with different flow topologies: (i) an exponential growth and (ii) nonlinear saturation during which these global quantities remain almost time independent with P ∼ D . The impact of a "strong" imposed magnetic field ( B = 2.5 ) on large scale structures at the saturation stage is reflected by the formation of structures that look like filaments and there is no dominance of horizontal motion over the vertical (along the solid-rotation axis) one. The comparison between the spectra of kinetic energy E ( κ ) ( k ⊥ ) , E ( κ ) ( k ⊥ , k ‖ = 1 , 2 ) and E κ ) ( k ⊥ , k ‖ = 0 ) at the saturation stage reveals that, at large horizontal scales, the major contribution to E ( κ ) ( k ⊥ ) does not come only from the mode k ‖ = 0 but also from the k ‖ = 1 mode which is the most energetic. Only at very large horizontal scales at which E ( κ ) ( k ⊥ ) ∼ E 2 D ( κ ) ( k ⊥ ) , the flow is almost two-dimensional. In the wavenumbers range 10 ≤ k ⊥ ≤ 40 , the spectra E ( κ ) ( k ⊥ ) and E ( κ ) ( k ⊥ , k ‖ = 0 ) respectively follow the scaling k ⊥ − 2 and k ⊥ − 3 . Unlike the velocity field the magnetic field remains strongly three-dimensional for all scales since E 2 D ( m ) ( k ⊥ ) ≪ E ( m ) ( k ⊥ ) . At the saturation stage, the Alfvén ratio between kinetic and magnetic energies behaves like k ‖ − 2 for B k ‖ / ( 2 ε Ω ) < 1 .
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Sung, Peng-Cheng, Chia-Ming Lai, Yunsen Wang i Yuan-Shyi P. Chiu. "Minimization of multiproduct fabrication cost featuring rework, commonality, external provider, and postponement". Uncertain Supply Chain Management 10, nr 2 (2022): 353–64. http://dx.doi.org/10.5267/j.uscm.2022.1.003.
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This study presents a multiproduct fabrication cost-minimization model featuring external providers, commonality, rework, and postponement in the supply chain environment. Customers’ requirements simultaneously emphasize quality, variety, and fast response time in current markets. To satisfy customer needs, most manufacturers in various industries (e.g., clothing, household goods, automotive, etc.) plan their multiproduct fabrication by incorporating a postponement strategy, rework process, and an outsourcing option. Motivated by the viewpoints above, this study offers a decision support system to address customers’ external expectations while optimizing internal operating expenses and machine utilization. We propose a single-machine, two-stage delayed differentiation system under a rotation cycle policy. All needed common parts are made in stage one, and stage two fabricates different end products. An external provider is hired to supply partially needed common parts to shorten uptime. The defective items are inevitably produced in both stages. They are categorized and reworked to maintain the desired product quality. Finally, we derive an optimal cost-minimization rotation cycle for our model and use a numerical example to investigate the collective and individual influences of reworking, postponement, and outsourcing to external providers on the multiproduct fabrication problem. In summary, this study can offer an optimization solution for production planning in various modern industries.
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Zhang, Chaowei, Xuezhi Dong, Xiyang Liu, Qing Gao, Chunqing Tan i Detang Zeng. "One-dimensional modeling for tip clearance leakage vortex trajectory and stall-onset prediction in subsonic centrifugal impellers". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, nr 3 (24.06.2019): 263–82. http://dx.doi.org/10.1177/0957650919856737.
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Two one-dimensional models are established for the tip leakage vortex trajectory and rotating stall-onset point prediction respectively for subsonic centrifugal impellers. The goal of modeling is to supply an effective estimation strategy of the stall-onset point for use in the one-dimensional performance prediction stage. The tip leakage vortex trajectory prediction is a critical part of the stall-onset prediction. The proposed one-dimensional model (one-dimensional tip leakage vortex trajectory model) to predict the tip leakage vortex trajectory is based on blade loading, i.e. the velocity difference between the pressure and suction surfaces. The loading function considers the effect of radial rotation, blade turning, and passage width variation. Compared with the computational fluid dynamics results, the current model shows reasonable accuracy, with an average relative error below 12.35%. The one-dimensional prediction model (Model II) is developed to determine the stall-onset point, where the interface between the tip leakage flow and the main flow spills from the blade leading edge. In this model, the momentum balance analysis is applied to identify the position of the interface. The parameter of the tip leakage vortex trajectory in Model II is determined by one-dimensional tip leakage vortex trajectory model. The effective origin of the tip leakage flow is correlated with the rotational speed and tip clearance. The effectiveness of Model II is validated with the experimental and computational fluid dynamics results using three impellers. Compared with the conventional model (Model I), Model II shows better accuracy, with a maximum error of about 7.42%.
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Ji, Mengyu, Gaoliang Peng, Jun He, Shaohui Liu, Zhao Chen i Sijue Li. "A Two-Stage, Intelligent Bearing-Fault-Diagnosis Method Using Order-Tracking and a One-Dimensional Convolutional Neural Network with Variable Speeds". Sensors 21, nr 3 (20.01.2021): 675. http://dx.doi.org/10.3390/s21030675.
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When performing fault diagnosis tasks on bearings, the change of any bearing’s rotation speed will cause the frequency spectrum of bearing fault characteristics to be blurred. This makes it difficult to extract stable fault features based on manual or intelligent methods, resulting in a decrease in diagnostic accuracy. In this paper, a two-stage, intelligent fault diagnosis method (order-tracking one-dimensional convolutional neural network, OT-1DCNN) is proposed to deal with the problem of fault diagnosis under variable speed conditions. Firstly, the order tracking algorithm is used to resample the monitoring data obtained under different rotation speeds. Then, the one-dimensional convolutional neural network is adopted to extract features of the fault data. Finally, the fault type of collected data can be obtained by fully connected networks based on the features extracted. In the time domain, while the proposed algorithm only relies on the fault data collected under one speed as the training dataset, it is capable of doing fault diagnosis under different speed conditions. In the condition with the largest difference in speed with each dataset, the accuracy of the proposed method is higher than the baseline methods by 0.54% and 11.00%—on CWRU dataset and our own dataset respectively. The results show that the proposed method performs well in dealing with the fault diagnosis under the condition of variable speeds.
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Cranswick, L. M. D., i R. L. Donaberger. "Total-scattering-based automatic centring of capillary samples within powder diffractometers". Journal of Applied Crystallography 41, nr 6 (11.10.2008): 1038–45. http://dx.doi.org/10.1107/s0021889808028562.
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A computer-controlled method for the automatic mechanical centring of a powder capillary sample onto the rotation centre of a powder diffractometer, using total scattering of the radiation beam into one-dimensional or two-dimensional detectors, and only a 90° rotation of the sample stage, is described. This method is particularly useful for situations where powder capillaries are within non-ambient experimental apparatus or loadedviaan automatic sample changer. Irregularly shaped samples, potentially subject to absorption effects, are aligned and centred on the sample's `scattering centre'.
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Prokhorenko, A., S. Kravchenko i E. Solodky. "METHOD OF ORGANIZING TWO-STAGE FUEL INJECTION INTO A DIESEL CYLINDER USING A HYDROMECHANICAL FUEL EQUIPMENT". Internal Combustion Engines, nr 2 (15.11.2022): 25–32. http://dx.doi.org/10.20998/0419-8719.2022.2.04.
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The use of multiphase injection allows reducing the emission levels with exhaust gases and the noise of diesel engines. This paper proposes to improve the hydromechanical fuel supply system of diesel vehicles by providing the possibility of two-stage fuel supply. This task is solved by high-pressure fuel pump equipment, additionally by high-pressure sections that work to inject fuel for pilot injection. The drive shaft cams of these sections are ahead of the shaft cams of the main sections by 2-10 degrees rotation of the camshaft. In order to check the performance of the proposed two-stage fuel supply system and to confirm the possibility of achieving its stated parameters, calculation studies were performed based on mathematical modeling of hydromechanical processes in this system.
Calculation studies were carried out using a mathematical model of the high-pressure fuel system of the Ch12/14 research single-cylinder diesel engine. The mathematical model is implemented in the MATLAB programming environment. Test results of calculations according to this mathematical model for the operating mode of the system at a camshaft rotation frequency of 650 min-1 and full fuel supply, the high-pressure system provides two-stage injection with the following indicators: total cyclic fuel supply 64 mm3/cycle, pilot dose - 9 mm3/cycle (which is 16% of the total cyclical supply); the maximum injection pressure is 49 MPa with a maximum pressure of 58 MPa in the over-plunger cavity; the maximum injection pressure of the pilot dose is 14.7 MPa, while the pressure reached in the over-plunger cavity is 26.5 MPa; the duration of the injection of the pilot dose is about 2 degrees rotation of the camshaft, the main one - 4.7 degrees rotation of the camshaft.
The system also provides two-stage injection in modes according to the load (and speed) characteristics. When the load is reduced from the maximum by 35-40%, it does not affect the maximum injection pressure of the main part of the fuel at all speed modes of the system, after which there is a sharp drop of this parameter to the value of the maximum injection pressure of the pilot. The maximum injection pressure of the pilot dose practically does not depend on the speed mode and lies within 13.5-15 MPa. Since the amount of the pilot dose is not adjustable, it does not depend on the movement of the high-pressure fuel pump rail and is 2 mm3/cycle at a rotation frequency of 450 min-1, 6 mm3/cycle at a rotation frequency of 550 min-1 and 9 mm3/cycle at a rotation frequency of 650 min-1.
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Shen, Xixun, Congcong Zhang, Tao Zeng, Danhong Cheng i Jianshe Lian. "Understanding the microscopic deformation mechanism and macroscopic mechanical behavior of nanocrystalline Ni by the long-term stress relaxation test". International Journal of Modern Physics B 28, nr 20 (19.06.2014): 1450124. http://dx.doi.org/10.1142/s0217979214501240.
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The long-term stress relaxation tests with a relaxation time of about 7 h are performed on the bulk dense nanocrystalline Ni (with a mean grain size of 27 nm) pre-deformed at strain rate from 4.17 s-1- 4.17 × 10-6 s-1, where a phenomenon that the initial relaxation behavior of nc Ni depends on itself deformation history. That is, the nc Ni s pre-deformed at higher strain rate (not less than 4.17 × 10-3 s-1) exhibit a three-staged relaxation process from the initial near linear rapidly stress delayed (LRSD) stage and the subsequent lumber nonlinear stress delayed (LNSD) one and the final near linear slowly stress delayed (LSSD) one while only the later two stages are observed for the nc Ni s pre-deformed at low strain rate. The three-stage relaxation behavior is attributed to the transition from the initial dislocation-dominated plasticity to the mixture of dislocation motion and diffusion-based GB activity and finally to the entire diffusion-based GB activity including GB sliding or grain rotation in the rate-controlling deformation mechanism, which was illuminated by the attained three-staged strain rate sensitivity and activation volume and the exhaustion of mobile density of deformed nc Ni in the first two stages of relaxation. Such rate-controlling deformation mechanism well interpreted the macroscopic tensile mechanical behavior of nc Ni and simultaneously an optimizing strategy in improving the ductility of nc Ni is also mentioned.
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Wang, Jun Feng, i Kang Sun. "Based on One-Dimensional Model to Calculate the Critical Speed". Applied Mechanics and Materials 203 (październik 2012): 427–31. http://dx.doi.org/10.4028/www.scientific.net/amm.203.427.
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Use the simple geometric features of a one-dimensional model to calculate the rotor critical speed, the shaft use the beam element to simulate, considering the shear deformation, continuous mass, the rotation inertia and gyro effect, bearing simplified as linear stiffness and damping element, disc use the lumped mass element to simulate, considering the mass and the effect of inertia, finite element method is applied, established the rotor-bearing system dynamics model, through the example to validate, the results show that the model is the advantage of calculation on a smaller scale, solution speed and high precision, easy to adjust the parameters for the model, suitable for large needs to adjust the parameters in the early stage of design and analysis of the rotor-bearing system, it has great reference value for the design and analysis of rotor dynamics.
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Xu, Hao, Nianjin Ye, Guanghui Liu, Bing Zeng i Shuaicheng Liu. "FINet: Dual Branches Feature Interaction for Partial-to-Partial Point Cloud Registration". Proceedings of the AAAI Conference on Artificial Intelligence 36, nr 3 (28.06.2022): 2848–56. http://dx.doi.org/10.1609/aaai.v36i3.20189.
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Data association is important in the point cloud registration. In this work, we propose to solve the partial-to-partial registration from a new perspective, by introducing multi-level feature interactions between the source and the reference clouds at the feature extraction stage, such that the registration can be realized without the attentions or explicit mask estimation for the overlapping detection as adopted previously. Specifically, we present FINet, a feature interactionbased structure with the capability to enable and strengthen the information associating between the inputs at multiple stages. To achieve this, we first split the features into two components, one for rotation and one for translation, based on the fact that they belong to different solution spaces, yielding a dual branches structure. Second, we insert several interaction modules at the feature extractor for the data association. Third, we propose a transformation sensitivity loss to obtain rotation-attentive and translation-attentive features. Experiments demonstrate that our method performs higher precision and robustness compared to the state-of-the-art traditional and learning-based methods. Code is available at https://github.com/megvii-research/FINet.
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Chen, Yili, Xiaoyu Huang, Yongzhong Cheng, Jingjing Xu, Yang Chen, Qi Zhang i Jianmin Wen. "Effects and Anti-rotation Stabilization of the Non-bridging External Fixation for Pronation-Abduction Stage III Ankle Fracture: A Cadaveric Study". BioMed Research International 2021 (8.05.2021): 1–11. http://dx.doi.org/10.1155/2021/9966344.
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Objective. This study is aimed at providing a nonbridging external fixation technique with pinning fixation for the pronation-abduction stage III ankle fracture. The secondary purpose was to evaluate its effect on anatomic reduction and fracture fragment stability against cadaveric models’ rotation. Method. A paired design study was conducted using 14 pairs of the cadaveric model which had been modeled for pronation-abduction stage III ankle fracture. One fracture model from each pair was randomly allocated to receive an open reduction and internal fixation, while the other was reduced and stabilized with the external fixation technique. After the surgery, the antirotational stability tests were performed with external rotation torques of 10 nm, 15 nm, and 20 nm applied, respectively. The postoperation reduction rate and ankle parameters were recorded in anteroposterior and lateral radiographs before and after the antirotational stability experiment. Result. The outcomes were assessed according to Burwell-Charnley’s radiographic criteria of reduction. It showed no statistically significant differences in reduction between the two groups ( P < 0.05 ). The displacement of lateral fragment following a reduction in the external fixation group was significantly larger than that of the internal fixation group ( 3.14 ± 0.56 vs. 1.49 ± 0.39 , P < 0.05 ). After applying rotational torques of 10 nm, 15 nm, and 20 nm, the results of other parameters showed no significant differences between the two groups. Conclusion. This nonbridging external fixation method with pin fixation of fracture fragments might have the same effect as that of internal fixation on the reduction rate of pronation-abduction stage III ankle fracture.
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Thahir, Muhammad, B. Suresh Gandhi, Kalaivanan Kanniyan i Shanmugasundaram . "A simple innovative Chennai handshake technique for reducing anterior dislocation of shoulder joint: a community study of 60 cases". International Journal of Research in Orthopaedics 3, nr 6 (25.10.2017): 1084. http://dx.doi.org/10.18203/issn.2455-4510.intjresorthop20174700.
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<p class="abstract"><strong>Background:</strong> Anterior shoulder dislocation is one of the commonest dislocation of our body. We here by introduce a simple, safe, successful and easily reproducible “Chennai Handshake Technique” to relocate anterior dislocation of shoulder joint.</p><p class="abstract"><strong>Methods:</strong> This method was performed by a single surgeon on sixty cases (51 males, 9 females) of anterior shoulder dislocation with a mean age of 38 years (18 to 58 years) between 2008 to 2013 in tertiary care center. Among sixty patients, there were 12 cases (20%) of fresh dislocation and 48 cases (80%) of recurrent dislocation. It comprises of holding the hand in a classical double shake position and then giving a gentle longitudinal traction (stage I) followed with slow abduction and external rotation of arm (stage II), thus reducing the shoulder dislocation. Vertical oscillation may be a part of stage II in some cases before the external rotation.<strong></strong></p><p class="abstract"><strong>Results:</strong> The index time of patient presenting to the casualty ranged from one hour to 18hrs with a mean of 4.45 hrs. The reduction time ranged from 1 to 16 min with a mean of 5.6 min. 17 dislocations (28.3%) were reduced during stage I. 41 dislocations (68.3%) were reduced during stage II. 5 dislocations (12.1%) needed vertical oscillation during stage II. we failed in two cases (3.3%).</p><p><strong>Conclusions:</strong> No need of assistant, no need of anesthesia, no complications makes this technique, a more look back one.</p>
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Maciąg, Bartosz M., Tomasz Kordyaczny, Grzegorz J. Maciąg, Marcin Łapiński, Dawid Jegierski, Jakub Świderek, Hanna Tsitko i in. "Comparison of Femoral Component Rotation between Robotic-Assisted vs. Soft-Tissue Tensor Total Knee Arthroplasty with Anatomic Implants". Medicina 59, nr 5 (4.05.2023): 880. http://dx.doi.org/10.3390/medicina59050880.
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Background and Objectives: Total knee arthroplasty (TKA) is the most effective treatment method for end-stage osteoarthritis. One of the most important aspects of this surgery is adequate implant positioning, as it guarantees the desired outcome of restoring limb biomechanics. Surgical technique is being continuously improved along with hardware development. There are two novel devices designed to help establish proper femoral component rotation: soft-tissue tensor and robotic–assisted TKA (RATKA). This study compared the femoral component rotation achieved with the use of three methods: RATKA, soft tissue tensioner and the conventional measured-resection technique, all of them utilizing anatomical design prosthesis components. Materials and Methods: A total of 139 patients diagnosed with end-stage osteoarthritis underwent total knee arthroplasty between December 2020 and June 2021. After the surgery, they were divided into three groups depending on procedure technique and implant type: Persona (Zimmer Biomet) + Fuzion Balancer, RATKA + Journey II BCS or conventional TKA + Persona/Journey. Postoperatively, a computed tomography examination was performed in order to measure femoral component rotation. All three groups were compared independently during statistical analysis. Fisher’s exact, Kruskal–Wallis and Dwass–Steel–Crichtlow–Fligner tests were used for particular calculations. Results: Statistically significant differences in femoral component rotation between groups were noticed. However, in terms of values other than 0° in external rotation, no significant variance was revealed. Conclusions: Additional total knee arthroplasty instruments seem to improve the outcomes of the surgery, providing better component positioning than in the conventional measured-resection technique based only on bone landmarks.
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Ebraheim, Nabil A., Anis O. Mekhail i Scott S. Gargasz. "Ankle Fractures Involving the Fibula Proximal to the Distal Tibiofibular Syndesmosis". Foot & Ankle International 18, nr 8 (sierpień 1997): 513–21. http://dx.doi.org/10.1177/107110079701800811.
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Thirty-two cases of ankle fractures associated with fibular fractures above the distal tibiofibular syndesmosis were studied. All were treated with open reduction and internal fixation. The average follow-up was 25 months. The results of the postoperative evaluation were rated, based on subjective clinical criteria, as good, fair, and poor. According to the Lauge-Hansen classification, there were 17 (53%) cases of supination-external rotation injury (2 stage 2 and 15 stage 4), 9 (28%) cases of stage 3 pronation-abduction injury, and 6 (19%) cases of pronation-external rotation injury (3 stage 3 and 3 stage 4). All cases could be classified as Weber type C or as suprasyndesmotic, fibular diaphyseal fracture (44-C) according to the Orthopaedic Trauma Association classification. In 18 (56%) cases, the fracture was associated with ankle dislocation. There were seven (22%) open fractures (two grade I, four grade II, and one grade IIIA). Syndesmotic screws were used in 23 (72%) cases (12 supination-external rotation injury, 6 pronation-external rotation injury, and 5 pronation-abduction injury). The syndesmotic screw was removed after an average of 9 weeks. Four (13%) nonunions and two (6%) delayed unions of the fibula were treated with bone grafting and/or hardware revision and eventually healed. Three of the nonunions had poor clinical results because of degenerative ankle joint arthritis in two (one of them ended in arthrodesis) and deep infection, which was eventually cured, in the third. The fourth nonunion had a fair result. One of the delayed unions had a fair result (an obese patient) and the other had a good result. Two patients developed deep infections; one ended in gangrene and amputation in a diabetic patient, and the other was a patient with fibular nonunion that eventually healed. Three patients had superficial infections that were treated successfully. Of the 32 cases, 23 (72%) showed good results, 4 (13%) showed fair results, and 5 (16%) showed poor results. The cases with poor results included three fibular nonunions, one deep infection, and one recurrent superficial infection and wound dehiscence after hardware removal. A syndesmotic screw is usually needed in cases of fracture-dislocations. Two patients with occult fibular nonunions developed diastasis of the syndesmosis after removal of the syndesmotic screw. It was found that reduction and temporary pinning of the distal tibiofibular joint helps achieve fibular length, which is crucial to restoring the biomechanics of the ankle joint. It seems advisable not to remove the syndesmotic screw until there are signs of healing of fibular fracture to avoid diastasis of the distal tibiofibular joint. Bone grafting should be considered in high energy fractures with comminution. These complex injuries are associated with higher rates of complications. Poor results can be attributed to fracture factors, e.g., open fractures, infections; patient factors, e.g., obesity, lowered immunity as in diabetes, and noncompliance; and iatrogenic factors, e.g., early removal of syndesmotic screws.
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Naghdy, Soroosh, Hadi Pirgazi, Patricia Verleysen, Roumen Petrov i Leo Kestens. "Morphological and crystallographic anisotropy of severely deformed commercially pure aluminium by three-dimensional electron backscatter diffraction". Journal of Applied Crystallography 50, nr 5 (28.09.2017): 1512–23. http://dx.doi.org/10.1107/s1600576717012754.
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The aim of this paper is to examine the morphological and crystallographic anisotropy that develops during high-pressure torsion (HPT) processing. Commercially pure aluminium was subjected to monotonic HPT deformation at room temperature. The microstructure and texture were studied by large-area electron backscatter diffraction (EBSD) scans. Three-dimensional EBSD scans served to scrutinize the morphological anisotropy and local texture. It was observed that two distinct stages of grain fragmentation and saturation occur during processing. Grains exhibited an ellipsoidal shape rather than an equi-axed one. The major axes of the ellipsoids showed a favorable orientation at the steady-state stage: an almost 20° inclination towards the shear direction. The global texture was characterized by typical shear components of face-centered cubic metals at both stages. However, the local texture revealed a preferential fragmentation pattern in the first stage: orientations in the vicinity of ideal fibers became less heavily fragmented while non-ideal orientations broke up more severely. This phenomenon was linked with the lattice rotation required to bring an initial orientation close to a stable one. Although the texture weakened considerably in the fragmentation stage, the texture index did not further decrease in the saturation stage. Saturation of texture, grain refinement and formation of microstructure are discussed in the light of different microstructural coarsening mechanisms.
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Gönczy, Pierre, Heinke Schnabel, Titus Kaletta, Ana Duran Amores, Tony Hyman i Ralf Schnabel. "Dissection of Cell Division Processes in the One Cell Stage Caenorhabditis elegans Embryo by Mutational Analysis". Journal of Cell Biology 144, nr 5 (8.03.1999): 927–46. http://dx.doi.org/10.1083/jcb.144.5.927.
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To identify novel components required for cell division processes in complex eukaryotes, we have undertaken an extensive mutational analysis in the one cell stage Caenorhabditis elegans embryo. The large size and optical properties of this cell permit observation of cell division processes with great detail in live specimens by simple differential interference contrast (DIC) microscopy. We have screened an extensive collection of maternal-effect embryonic lethal mutations on chromosome III with time-lapse DIC video microscopy. Using this assay, we have identified 48 mutations in 34 loci which are required for specific cell division processes in the one cell stage embryo. We show that mutations fall into distinct phenotypic classes which correspond, among others, to the processes of pronuclear migration, rotation of centrosomes and associated pronuclei, spindle assembly, chromosome segregation, anaphase spindle positioning, and cytokinesis. We have further analyzed pronuclear migration mutants by indirect immunofluorescence microscopy using antibodies against tubulin and ZYG-9, a centrosomal marker. This analysis revealed that two pronuclear migration loci are required for generating normal microtubule arrays and four for centrosome separation. All 34 loci have been mapped by deficiencies to distinct regions of chromosome III, thus paving the way for their rapid molecular characterization. Our work contributes to establishing the one cell stage C. elegans embryo as a powerful metazoan model system for dissecting cell division processes.
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Watanabe, Shuhei. "One-shot Multi-angle Measurement Device for Evaluating the Sparkle Impression". Electronic Imaging 2020, nr 5 (26.01.2020): 60401–1. http://dx.doi.org/10.2352/issn.2470-1173.2020.5.maap-120.
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The quantification of material appearance is important in product design. In particular, the sparkle impression of metallic paint used mainly for automobiles varies with the observation angle. Although several evaluation methods and multi-angle measurement devices have been proposed for the impression, it is necessary to add more light sources or cameras to the devices to increase the number of evaluation angles. The present study constructed a device that evaluates the multi-angle sparkle impression in one shot and developed a method for quantifying the impression. The device comprises a line spectral camera, light source, and motorized rotation stage. The quantification method is based on spatial frequency characteristics. It was confirmed that the evaluation value obtained from the image recorded by the constructed device correlates closely with a subjective score. Furthermore, the evaluation value is significantly correlated with that obtained using a commercially available evaluation device.