Academic literature on the topic 'Two stage rotation'
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Journal articles on the topic "Two stage rotation"
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Powers, Michael E. "Rotator Cuff Training for Pitchers." Journal of Sport Rehabilitation 7, no. 4 (November 1998): 285–99. http://dx.doi.org/10.1123/jsr.7.4.285.
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This paper reviews the role of the rotator cuff during two key phases of the pitching sequence and presents a training program for these muscles. The program uses a periodization design consisting of three stages, beginning with a high-resistance/low-repetition eccentric strengthening stage. This is followed by a low-resistance/high-repetition stage for training muscular endurance. The core exercises for these two stages are prone external rotation in the 90/90 position, prone horizontal abduction, side-lying D2 flexion pattern, supine internal rotation in the 90/90 position, prone elevation with 100° of shoulder abduction and external rotation, and standing scapular plane elevation. The final stage of the program uses high-speed functional exercises: 90/90 external rotation, 90/90 internal rotation, D2 PNF flexion pattern, D2 PNF extension pattern, supine plyometric 90/90 internal rotation with a medicine ball, and the “arm whip” through the D2 PNF flexion pattern. The goal of this program is to prepare the muscles for the stresses of pitching and prevent shoulder injuries.
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Alkadhimi, Aslam. "A novel and simple technique for correcting localised rotations in the early alignment stage." Journal of Orthodontics 47, no. 4 (August 27, 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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Panov, V. F., O. V. Sandakova, E. V. Kuvshinova, and D. M. Yanishevsky. "Evolution of the Universe with two rotating fluids." International Journal of Modern Physics A 35, no. 02n03 (January 30, 2020): 2040042. http://dx.doi.org/10.1142/s0217751x20400424.
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An anisotropic cosmological model with expansion and rotation and the Bianchi type IX metric has been constructed within the framework of general relativity theory. The first inflation stage of the Universe filled with a scalar field and an anisotropic fluid is considered. The model describes the Friedman stage of cosmological evolution with subsequent transition to accelerated exponential expansion observed in the present epoch. The model has two rotating fluids: the anisotropic fluid and dust-like fluid. In the approach realized in the model, the anisotropic fluid describes the rotating dark energy.
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Ito, Yoichiro. "Two-phase Motion in Hydrodynamic Counter-current Chromatography." Current Chromatography 7, no. 2 (December 29, 2020): 76–81. http://dx.doi.org/10.2174/2213240606666190912161221.
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Background: Motion of the two mutually immiscible liquids in hydrodynamic countercurrent chromatographic systems is speculated based on the observation of their behavior in a closed coiled tube rotating in unit gravity. Materials and Methods: The experiment revealed an up and down pattern of four stages of twophase volume ratio occupied at the head end of the coil according to the rotation speed. These two-phase behaviors are comprehensively explained on the bases of interplay between the unit gravity and centrifugal force generated by rotation of the coil. This theory is successfully extended to explain the two-phase behavior in a coil undergoing the type-I and type-J planetary motions. Results and Discussion: The type-I planetary motion produces the centrifugal force distribution similar to that of slowly rotating coil in unit gravity (Stage I), where both phases competitively move toward the head of the coil. In contrast, the type-J planetary motion displays complex distribution patterns of centrifugal force according to the location of the coil on the holder hence the two-phase motion varies with the ß values. When ß is 0.5 – 0.75, the force pattern simulates that of the rotating coil in unit gravity at 120 rpm (Stage III) where the lighter phase moves toward the head leaving the heavier phase behind. Conclusion: This clearly demonstrates the importance of the proper choice of ß values in highspeed countercurrent chromatography utilizing the type-J planetary motion.
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Wei, Zhicong, Wei Yang, and Ruofu Xiao. "Pressure Fluctuation and Flow Characteristics in a Two-Stage Double-Suction Centrifugal Pump." Symmetry 11, no. 1 (January 8, 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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Luan, Hengxuan, Liyuan Weng, Ranhui Liu, Dongmin Li, and Mingwei Wang. "Axial Spacing Effects on Rotor-Rotor Interaction Noise and Vibration in a Contra-Rotating Fan." International Journal of Aerospace Engineering 2019 (February 7, 2019): 1–15. http://dx.doi.org/10.1155/2019/2125976.
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Because of the potential technical advantages, the contra-rotation technology has become a renewed interest in aviation and other applications. Contra-rotation increases efficiency in comparison with the single-rotor design, but this advantage is not fully harnessed. The axial spacing of two-stage contra-rotating blade rows has a significant impact on a contra-rotating fan/compressor. The results show that with a contra-rotation pattern, the strong unsteadiness of two-stage rotors is caused by the rotor-rotor interaction. The unsteadiness of rotor 1 is caused by the potential disturbance, and the upstream wake leads to the strong unsteadiness of rotor 2. With the increase of axial spacing, the rotor-rotor interaction is weakened, while unsteady features of two-stage rotor blades tend to be consistent. The acoustic and vibration effects of axial spacing are studied. It is found that the axial spacing has great influence of aerodynamic noise. The mean value of sound pressure level decreases by 17.2 dB in total when the axial spacing increased to 1.1 chord from 0.3 chord. For the accuracy of calculation, the scattering effect of the casing wall should be considered in the prediction of the noise. The axial spacing does not have obvious effects on the natural frequencies of the two-stage rotor blades but has certain effect on blade deformation.
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Ye, Tingting, and Yangmin Li. "Synthesis of 2-DOF Decoupled Rotation Stage with FEA-Based Neural Network." Processes 11, no. 1 (January 6, 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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Gurney, Kevin, and Michael J. Wright. "Rotation and Radial Motion Thresholds Support a Two-Stage Model of Differential-Motion Analysis." Perception 25, no. 1 (January 1996): 5–26. http://dx.doi.org/10.1068/p250005.
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Lower motion thresholds for rotational and radial flow have been measured for stimuli consisting of four closely packed circular apertures, each containing patches of drifting grating or plaid. Detection and direction thresholds were measured for gratings and plaids as a function of the relative orientation of the pattern components. There was a similarity between both types of threshold, supporting the existence of specialised rotation and radial-flow detectors. Further, thresholds increased with the relative component orientation for both gratings and plaids. This suggests that component information from a first stage, tuned spatiotemporally and to orientation, is being used directly to compute the optic flow in a two-stage process. A model based on this architecture is described by means of simple template receptive-field arrays with separable temporal and spatial tuning at the first stage.
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Zhang, Lei, and Abraham Engeda. "Numerical simulation of rotating stall in a two-stage axial fan." Thermal Science 22, Suppl. 2 (2018): 655–63. http://dx.doi.org/10.2298/tsci171025050z.
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Computational fluid dynamics calculations using high-performance parallel computing were conducted to simulate the prestall flow of a two-stage axial fan. The simulations were run with a full-annulus grid that models the 3-D, viscous, unsteady blade row interaction without the need for an artificial inlet distortion to induce stall. The simulation shows the initiation and development of the stall inception in two rotors of the axial fan. The results show that the stall inception first occurs in the second stage. The spike-type stall inception occurred in the second stage, which is different from the common views. The starting positions of stall inception in both rotors are in the same circumferential direction, and the stall inceptions in both rotors turn into mature stall cells at the same time. Also, the rotation speed of the stall inception and rotating stall in the two rotors are the same. The rotating stall in the first and second stage rotor impellers are both directly induced by the blade tip leakage flow. However, the blocked flow in the second stage rotor strengthens the leakage flow in the blade tip of the first stage rotor indirectly, resulting in the formation of stall inception.
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Malael, I., and V. Dragan. "Numerical and Experimental Efficiency Evaluation of a Counter-Rotating Vertical Axis Wind Turbine." Engineering, Technology & Applied Science Research 8, no. 4 (August 18, 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.
Dissertations / Theses on the topic "Two stage rotation"
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Springfield, James L. "Spectroscopy and Structure of Intermolecular Clusters and Rotational State-To-State Differential Cross-Sections for the HCI-X Collison System." Thesis, Griffith University, 2005. http://hdl.handle.net/10072/365402.
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One Colour-Resonant Two-Photon Ionisation, coupled with a supersonic expansion was used to study the rotationally cold excited electronic states of the water clusters of ortho-, meta- and para-difluorobenzene. Ground state rotational constants obtained through ab-initio calculations allowed rotational band contour simulations of these species to be performed, elucidating structural and spectroscopic features such as rotational band types, directions of transition dipole moments and excited state geometries. Confidence in the calculated ground state geometries, obtained through successful simulation of the rotational band contours, provided strength to the credibility of the vibrational frequencies acquired via these calculations. Analysis of ground state dispersed fluorescence spectroscopy utilising these ab-initio (geometry + frequency) optimisation calculations, allowed assignment of the ground state vibrational modes of each species. Furthermore, comparison of the assigned ground state modes with the excited state spectroscopy, affirmed assignment of the low frequency Van der Waals modes along with the higher frequency aromatic ring modes of these cluster species.
A novel technique that produces pseudo-selective excitation of ground state aromatic-rare gas cluster ions was used to assign the vibrational transitions of the D3[less than]D0 electronic excitation spectrum of para-Difluorobenzene+-Argonn=1,2. This technique works on the principle of providing varying degrees of excess energy to the ground state of the cluster ion, as well as altering the Franck-Condon factors for excitation to the D3 electronic state. Measurement of the redshifts for each pDFB-R (where R= Ar1, Ar2, Kr1, Kr2) cluster, revealed that the addition of a second rare-gas adatom doubled the redshift, and that Krypton ad-atoms produced a stronger redshift than argon as expected. It was also noted that the addition of a positive charge to the complex increased the redshift of the complexes, in accordance with our expectations. Rotational state-resolved differential cross sections (DCS's) for rotationally inelastic collisions of HCl with Ne, Ar, and Kr at ~545, ~538, and ~526 cm-1 of collision energy, respectively, were measured using velocity-mapped ion imaging. For each rotational state, the observed DCS's were found to be qualitatively similar. As collider mass was increased, the differential cross section became increasingly forward scattered. Calculations suggest that much of this difference is due to kinematic effects, but that the potential energy surface should be slightly more anisotropic for heavier colliders.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Science
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Vrbka, Tomáš. "Návrh dvoustupňového čerpadla s protiběžnými koly na zadané parametry." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378486.
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This diploma thesis deals with hydraulic design and optimization of the blades of the axial pump. Main objective of the thesis is to design two stage pump with counter-rotating rotors meeting conditions of design point. In addition to the design solution the thesis includes theoretical part which deals with dividing and function description of hydrodynamic pumps.
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Gordon, Sean Dennis Steven. "Two and three vector correlations in the rotationally inelastic scattering of state-selected NO(X)." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:ec0f133b-b2ef-482c-b90c-59fc313c8baa.
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In this thesis, an experimental and theoretical study of two and three vector correlations in the inelastic scattering of NO(X) with various rare gas atoms is presented. Vector correlations for a selection of rare gas systems were determined experimentally, and the observations were interpreted using a variety of classical and quantum mechanical models. The experiment is able to provide state-to-state resolution of the dynamics by means of an electrostatic hexapole and 1+1' resonantly enhanced multi-photon ionisation (REMPI). The simplest vector correlation of interest is the differential cross section (DCS), given by the k-k' correlation. The DCSs were determined experimentally for the NO(X)--Kr and NO(X)--Xe collision systems, both characterised by the relatively deep (≈140cm-1) attractive well and large extent of the attractive potential. The agreement between the experimental angular distributions and quantum mechanical DCS is very good for both systems. Classical calculations fail to correctly reproduce the form and magnitude of the DCS for either system, reflecting the inherently quantum mechanical nature of the collision. The classical calculations do however provide mechanistic insight into regions where the attractive part of the potential plays an important role in determining the dynamics. In order to investigate narrow angular features in the forward scattered direction, several experimental improvements to molecular beams and the detection ion-optic stack were made. Investigation into these structures revealed a strong contribution from molecular diffraction into the classical shadow of the NO(X), and the simple Fraunhofer model revealed a preference for scattering from an individual m→m' sub-state. Such measurements are in a region of the DCS where scattering is forbidden classically, and reveal the purely quantum nature of the collision interaction in the forward scattered direction. The low order k-k' correlation was then extended by using linearly or circularly polarised laser excitation. The interaction of the light with the molecular dipole allows the measurement of the k-k'-j' correlation. When linearly polarised light was used for the excitation laser, two of the rank two p{2}q(θ) renormalised polarisation dependent differential cross sections (PDDCSs), which describe rotational alignment, were obtained. With circularly polarised light, the rank one p{1}1-(θ) renormalised PDDCSs describing rotational orientation were determined. The collision induced alignment in NO(X)--Xe scattering was found to be well reproduced by classical and impulsive theories, highlighting the fact that the alignment is dominated by the propensity for the projection of j onto the kinematic apse to be conserved. The attractive part of the potential does augment the alignment renormalised PDDCSs, and this is most evident in states with strong features of the attractive part of the potential such as ℓ-type rainbows. The orientation is more strongly influenced by the attractive part of the potential and is also influenced by parity. In addition to the parity effect, there exist two limiting classical mechanisms which govern the orientation, one caused by attraction and the other repulsion. Finally, the bond axis of the NO(X) can be oriented by means of hexapole state selection combined with adiabatic orientation using a set of guiding rods. The integral steric effect, an r-k correlation, was measured for the NO(X)--Kr and NO(X)--Ar spin-orbit changing systems. There are large oscillations in the sign of the steric asymmetry which occur for scattering with the various rare gases. There are also large differences between the rare gases as the potentials become more attractive, and more isotropic. The steric asymmetry is well reproduced by quantum mechanics, however, a classical mechanism becomes dominant at high Δj.
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Wagner, Alec Thomas. "Fundamental Studies of Two Important Atmospheric Oxidants, Ozone and Hydroxyl Radical, Reacting with Model Organic Surfaces." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/45093.
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Heterogeneous reactions between gas-phase oxidants and particulate-phase organic compounds impact many important atmospheric chemical processes. For example, little is known about the reaction dynamics of gaseous oxidants with organic compounds found in the atmosphere. The first step of the reaction between gaseous ozone and solid pentacene was investigated using Reflection Absorption Infrared Spectroscopy (RAIRS). Ozone was found to add to pentacene non-selectively and form a range of products after heavy ozone exposure. The rate limiting step had an activation energy of 17 kJ/mol, which is consistent with the findings of previous ozone oxidation studies for the cleavage of a carbon-carbon double bond. Unfortunately the products could not be used to distinguish between probable reaction mechanisms.
Hydroxyl radicals (•OH) play a major role processing atmospheric hydrocarbons. Due to their short lifetimes, not much is known about the dynamics of the first steps of •OH reactions. To investigate these reactions, a rotational state-selector was constructed to filter a molecular beam of •OH for reaction dynamics investigations with organic surfaces. The rotational state-selector was designed to leverage the linear Stark effect to pass only suitable molecules in a particular rotational state and block the flow of any other atoms, molecules and ions in a molecular beam. The state-selector was validated and used to positively deflect molecular beams of methyl iodide and D₂O via the linear Stark effect. Future studies with the rotational state-selector will investigate the initial steps of •OH reactions with solid organic compounds.Master of Science
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Ryderfors, Linus. "Two-Photon Excited Fluorescence Depolarisation : Experimental and Theoretical Development." Doctoral thesis, Uppsala University, Department of Photochemistry and Molecular Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9285.
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We have studied fundamental aspects of time-resolved two-photon excited fluorescence depolarisation. The thesis presents experimental as well as theoretical progress. We show that a multi-photon induced instrumental response function obtained from a suspension of gold nanoparticles is appropriate for the analysis of two-photon excited fluorescence decays obtained using time-correlated single photon counting detection. Theoretical expressions have been derived for the fluorescence anisotropy decay obtained upon two-photon excitation of various molecular systems in liquid solutions: a) an anisotropic rigid rotor that undergoes rotational diffusion in the presence of ultrafast unresolved restricted reorientations, e.g. librations. b) a molecular group covalently attached to a stationary macromolecule, and undergoing local reorientation in a uniaxial ordering potential. A new approach to the analysis of two-photon excited fluorescence depolarisation experiments was developed, which combines data obtained by using linearly and circularly polarised excitation light, in a global manner. In the analysis, knowledge about unresolved reorientations was obtained from one-photon excitation studies of the corresponding systems. By means of this procedure it has been possible to obtain quantitative information about the molecular two-photon absorption tensor for perylene and two of its derivatives. Thereby the symmetry of the final excited and intermediate vibronic states could be assigned. The analysis reveals that the two-photon transition studied with the 800 nm laser exhibits mixed character. An important finding from the experiments was that the two-photon absorption tensor appears to be solvent dependent. Furthermore, the thesis presents the first theoretical treatment of two-photon excited donor-donor energy migration in the presence of molecular reorientation and which applies the extended Förster theory. Explicit expressions for molecules that belong to the point groups D2h, D2 and C2v are given. Preliminary experiments are finally also reported on a two-photon excited donor-donor energy migration system consisting of a bisanthryl-bisteroid.
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Ghalehchian, Javad Saien. "Evaluation of liquid-liquid extraction column performance for two chemical systems : a study for application of drop breakage, hydrodynamic and mass transfer models in a computer program to simulate the steady state behaviour of a rotating disc contactor for liquid-liquid extraction." Thesis, University of Bradford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.578243.
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Vestin, Albin, and Gustav Strandberg. "Evaluation of Target Tracking Using Multiple Sensors and Non-Causal Algorithms." Thesis, Linköpings universitet, Reglerteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-160020.
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Today, the main research field for the automotive industry is to find solutions for active safety. In order to perceive the surrounding environment, tracking nearby traffic objects plays an important role. Validation of the tracking performance is often done in staged traffic scenarios, where additional sensors, mounted on the vehicles, are used to obtain their true positions and velocities. The difficulty of evaluating the tracking performance complicates its development. An alternative approach studied in this thesis, is to record sequences and use non-causal algorithms, such as smoothing, instead of filtering to estimate the true target states. With this method, validation data for online, causal, target tracking algorithms can be obtained for all traffic scenarios without the need of extra sensors. We investigate how non-causal algorithms affects the target tracking performance using multiple sensors and dynamic models of different complexity. This is done to evaluate real-time methods against estimates obtained from non-causal filtering. Two different measurement units, a monocular camera and a LIDAR sensor, and two dynamic models are evaluated and compared using both causal and non-causal methods. The system is tested in two single object scenarios where ground truth is available and in three multi object scenarios without ground truth. Results from the two single object scenarios shows that tracking using only a monocular camera performs poorly since it is unable to measure the distance to objects. Here, a complementary LIDAR sensor improves the tracking performance significantly. The dynamic models are shown to have a small impact on the tracking performance, while the non-causal application gives a distinct improvement when tracking objects at large distances. Since the sequence can be reversed, the non-causal estimates are propagated from more certain states when the target is closer to the ego vehicle. For multiple object tracking, we find that correct associations between measurements and tracks are crucial for improving the tracking performance with non-causal algorithms.
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Liao, Hsuan Ya, and 廖宣雅. "Using Two-Stage Optimization Model To Investigate Manpower Allocation And Job Rotation─ The Evidence of Nursing Staffs in a Hospital." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/51833938313876181184.
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碩士東海大學
企業管理學系碩士班
97
Taking care of patients is the main capability of hospital. To well perform the capability, human resource, the most important issue of hospital operation, needs to be considered seriously. Therefore, arranging human resources more flexibility to maximize its effectiveness is necessary. However, the mismatch of nursing management is still apparent in the hospital operation. To balance the nursing manpower’s supporting and allocating is the most urgent problem needs to be addressed. In this research, the two-stage optimization model is utilized to solve the problem of nursing allocating, and the Lingo 10.0 is used to find out the optimal choice. The objective of first-stage optimization model is a labor shortage function, and can be used to maximize the total departmental utility. In the second stage, the objective is to maximize the total improvement in skill levels of nurses, and the job rotation can be decided according to the improvement of skill levels. Furthermore, based on the two-stage optimization model, the utility of first stage is also considered in the second stage to ensure no reduction of departmental utility is induced. The result of this research reveals that the departmental shortage is decreased and hire people is also reduced after the first-stage optimization. In the second-stage optimization, the shortage further becomes zero because of skill improvement. Besides, for job rotation, assigning nurse with higher leaning rate to rotation not only can effectively increase nurse’s skill, but also enhance the flexibility of hospital staffing profoundly.
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Grobler, Jonathan. "Hypernuclear bound states with two /\-Particles." Diss., 2009. http://hdl.handle.net/10500/3222.
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The double hypernuclear systems are studied within the context of the
hyperspherical approach. Possible bound states of these systems are sought
as zeros of the corresponding three-body Jost function in the complex energy
plane. Hypercentral potentials for the system are constructed from known
potentials in order to determine bound states of the system. Calculated
binding energies for double- hypernuclei having A = 4 − 20, are presented.Physics
M.Sc. (Physics)
Books on the topic "Two stage rotation"
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Vallejo Maldonado, Pablo Ramon, and Nikolay Chaynov. Kinematics and dynamics of automobile piston engines. ru: INFRA-M Academic Publishing LLC., 2019. http://dx.doi.org/10.12737/989072.
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The fundamentals of kinematics and dynamics of transport piston internal combustion engines made using different layout schemes are presented. Along with the traditional in-line, V-shaped, including oppositional, arrangement of cylinders, schemes with "staggered" arrangement of cylinders in the block at the displaced connecting rod necks of the crankshaft of the engine are considered. The kinematics of the coaxial crank mechanism is considered in detail. The questions of dynamics with reduction of calculated dependences of forces, moments, a choice of a rational order of work of cylinders in relation to the considered kinematic schemes are in detail stated. Considerable attention is paid to the unevenness of the crankshaft rotation speed and engine balancing. The loads on the main and connecting rod bearings of the crankshaft, the knowledge of which is necessary in determining the bearing capacity of bearing units, are also considered.
Meets the requirements of the Federal state educational standards of higher education of the last generation.
For students of higher educational institutions studying in the direction of training 23.03.03 "Operation of transport and technological machines and complexes" and related areas.
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Bachmann, Hugo, and Walter Ammann. Vibrations in Structures. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 1987. http://dx.doi.org/10.2749/sed003e.
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<p>«Vibrations in Structures» concentrates on vibrations in structures as excited by human motion or machine operation. Man-induced vibrations may arise from walking, running, skipping, dancing, etc. They occur mostly in pedestrian structures, office buildings, gymnasia and sports halls, dancing and concert halls, stadia, etc. Existing publications treat by and large some isolated aspects of the problem; the present one attempts, for the first time, a systematic survey of man-induced vibrations. Machine-induced vibrations occur during the operation of all sorts of machinery and tools with rotating, oscillating or thrusting parts. The study concentrates rather on small and medium size machinery placed on floors of industrial buildings and creating a potential source of undesirable vibrations. The associated questions have rarely been tackled to date; they entail probiems similar to those of man-induced vibrations.</p> <p>The book is consciously intended to serve the practising structural engineer and not primarily the dynamic specialist. It should be noted that its aim is not to provide directions on how to perform comprehensive dynamic computations. Instead, it attempts the following:</p> <ol> <li>to show where dynamic problems could occur and where a word of caution is good advice;</li> <li>to further the understanding of the phenomena encountered as well as of the underlying principles;</li> <li>to impart the basic knowledge for assessing the dynamic behaviour of the structures or structural elements;</li> <li>to describe suitable measures, both preventive to be applied in the design stage and remedial in the case of rehabilitation.</li> </ol>
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Pinna, Baingio. On the Pinna Illusion. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780199794607.003.0074.
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The Pinna illusion is the first case of visual illusion showing a rotating motion phenomenon. Squares, arranged in two concentric rings, show a strong counter-rotation effect. The inner ring of the squares appears to rotate counterclockwise and the outer ring clockwise when the observer’s head is slowly moved toward the figure while the gaze is kept fixed in the center of the stimulus pattern. The direction of rotation is reversed when the observer’s head moves away from the stimulus. The speed of the illusory rotation is proportional to the one of the motion imparted by the observer. While the way each individual check receives a local illusory motion signal can be explained by the response of direction-selective neurons at the earliest cortical stage of visual processing, the whole illusory rotational motion can be thought to be sensed by the higher cortical area, which collates all the signals provided by the local motion checks.
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Horing, Norman J. Morgenstern. Q. M. Pictures; Heisenberg Equation; Linear Response; Superoperators and Non-Markovian Equations. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198791942.003.0003.
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Three fundamental and equivalent mathematical frameworks (“pictures”) in which quantum theory can be lodged are exhibited and their relations and relative advantages/disadvantages are discussed: (1) The Schrödinger picture considers the dynamical development of the overall system state vector as a function of time relative to a fixed complete set of time-independent basis eigenstates; (2) The Heisenberg picture (convenient for the use of Green’s functions) embeds the dynamical development of the system in a time-dependent counter-rotation of the complete set of basis eigenstates relative to the fixed, time-independent overall system state, so that the relation of the latter fixed system state to the counter-rotating basis eigenstates is identically the same in the Heisenberg picture as it is in the Schrödinger picture; (3) the Interaction Picture addresses the situation in which a Hamiltonian, H=H0+H1, involves a part H0 whose equations are relatively easy to solve and a more complicated part, H1, treated perturbatively. The Heisenberg equation of motion for operators is discussed, and is applied to annihilation and creation operators. The S-matrix, density matrix and von Neumann equation, along with superoperators and non-Markovian kinetic equations are also addressed (e.g. the intracollisional field effect).
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Zeitlin, Vladimir. Rotating Shallow-Water model with Horizontal Density and/or Temperature Gradients. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198804338.003.0014.
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The derivation of rotating shallow-water equations by vertical averaging and columnar motion hypothesis is repeated without supposing horizontal homogeneity of density/potential temperature. The so-called thermal rotating shallow-water model arises as the result. The model turns to be equivalent to gas dynamics with a specific equation of state. It is shown that it possesses Hamiltonian structure and can be derived from a variational principle. Its solution at low Rossby numbers should obey the thermo-geostrophic equilibrium, replacing the standard geostrophic equilibrium. The wave spectrum of the model is analysed, and the appearance of a whole new class of vortex instabilities of convective type, resembling asymmetric centrifugal instability and leading to a strong mixing at nonlinear stage, is demonstrated.
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Rajeev, S. G. Euler’s Equations. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198805021.003.0002.
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Euler derived the fundamental equations of an ideal fluid, that is, in the absence of friction (viscosity). They describe the conservation of momentum. We can derive from it the equation for the evolution of vorticity (Helmholtz equation). Euler’s equations have to be supplemented by the conservation of mass and by an equation of state (which relates density to pressure). Of special interest is the case of incompressible flow; when the fluid velocity is small compared to the speed of sound, the density may be treated as a constant. In this limit, Euler’s equations have scale invariance in addition to rotation and translation invariance. d’Alembert’s paradox points out the limitation of Euler’s equation: friction cannot be ignored near the boundary, nomatter how small the viscosity.
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Henriksen, Niels Engholm, and Flemming Yssing Hansen. Introduction. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198805014.003.0001.
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This introductory chapter considers first the relation between molecular reaction dynamics and the major branches of physical chemistry. The concept of elementary chemical reactions at the quantized state-to-state level is discussed. The theoretical description of these reactions based on the time-dependent Schrödinger equation and the Born–Oppenheimer approximation is introduced and the resulting time-dependent Schrödinger equation describing the nuclear dynamics is discussed. The chapter concludes with a brief discussion of matter at thermal equilibrium, focusing at the Boltzmann distribution. Thus, the Boltzmann distribution for vibrational, rotational, and translational degrees of freedom is discussed and illustrated.
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Kislyuk, V. S. Moon in the Sky… PH “Akademperiodyka”, 2009. http://dx.doi.org/10.15407/akademperiodyka.126.120.
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The book “Moon in the Sky…” consists of two chapters: “The Wonderful World of Selena” and “Return to the Moon.” The first of them tells about the current state of the study of the Moon: its origin, features of rotational motion, nature and internal structure. The second section discusses the problems of further study and development of the Earth's natural satellite with the help of spacecraft and the creation of populated scientific and research-production bases on its surface. The appendices provide basic information about the Moon, a glossary of lunar terms, a chronology of lunar explorations using spacecraft, a map of the visible side of the Moon for observations with binoculars or a school telescope. The book “Moon in the Sky…” is intended for a wide range of readers.
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Martin, Jeffrey T. Sentiment, Reason, and Law. Cornell University Press, 2019. http://dx.doi.org/10.7591/cornell/9781501740046.001.0001.
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What if the job of police was to cultivate the political will of a community to live with itself (rather than enforce law, keep order, or fight crime)? This book describes a world where that is the case. The Republic of China on Taiwan spent nearly four decades as a single-party state under dictatorial rule (1949–1987) before transitioning to liberal democracy. This book describes the social life of a neighborhood police station during the first rotation in executive power following the democratic transition. It shows an apparent paradox of how a strong democratic order was built on a foundation of weak police powers, and demonstrates how that was made possible by the continuity of an illiberal idea of policing. The conclusion from this paradox is that the purpose of the police was to cultivate the political will of the community rather than enforce laws and keep order. As the book shows, the police force in Taiwan exists as an “anthropological fact,” bringing an order of reality that is always, simultaneously and inseparably, meaningful and material. It unveils the power of this fact, demonstrating how the politics of sentiment that took shape under autocratic rule continued to operate in everyday policing in the early phase of the democratic transformation, even as a more democratic mode of public reason and the ultimate power of legal right were becoming more significant.
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Kokkonen, Andrej, Jørgen Møller, and Anders Sundell. The Politics of Succession. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780192897510.001.0001.
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Abstract The problem of leadership succession is perennial; the death of the ruler poses a significant threat to the stability of any polity. Arranging for a peaceful and orderly succession has been a formidable challenge in most historical societies, and it continues to be a test that modern authoritarian regimes regularly face and often fail. There is in practice no optimal solution to the problem of who should succeed the ruler, at least not when power is vested in one person. The absence of a successor causes uncertainty and plotting; the existence of one creates another centre of power, with dangerous implications. This book documents how successions have historically been moments of violence and insecurity: The succession wars known from European history are simply the tip of the iceberg. But the book also shows that the development and spread of primogeniture—the eldest-son-taking-the-throne—mitigated the problem of succession in Europe in the period after AD 1000. Primogeniture presented a reasonable compromise that in ‘normal’ circumstances allowed for an orderly transfer of power while minimizing threats to the incumbent ruler. In a long-term historical perspective, father-to-son successions—in the context of hereditary monarchy—therefore created political stability and facilitated state-formation. Today, representative democracy does the same, but in a very different way where frequent rotations in power and guarantees against the misuse of power are used to lessen the stakes of leadership succession.
Book chapters on the topic "Two stage rotation"
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Zheng, Ziran, and Xiaoju Gong. "A Two-Stage Heuristic Approach for a Type of Rotation Assignment Problem." In Lecture Notes in Computer Science, 212–24. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-93818-9_20.
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Kersebaum, Kurt Christian. "Modelling to Evaluate Climate Resilience of Crop Rotations Under Climate Change." In Springer Climate, 87–93. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-86211-4_11.
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AbstractDiversification of crop rotations is considered as an option to increase the resilience of European crop production under climate change. Although crop rotation design and management has been identified as an important measure to adapt to and mitigate climate change, most studies on climate change impact or adaptation so far use single-year simulations and/or single crop assessments. Crop response to various management options within a growing season is generally taken into account by most crop models. However, if simulations neglect processes and fluxes between growing seasons and potential carry-over effects related to agronomic management, the long-term sustainability of adaptation and mitigation strategies cannot be properly evaluated. Therefore, the integrated assessment of impacts, adaptation and mitigation options under current and future climatic conditions requires a continuous long-term analysis of crop sequences to take into account carry-over effects as in real conditions. The present paper provides information on crop rotation aspects, which should be considered in modelling, presents the current state of modelling for climate impact assessment, address points of uncertainty and missing aspects in modelling and draws an outlook on potential future developments with special emphasis on crop rotations. In conclusion, crop models require suitable experimental data to parameterize additional crops, which were so far not sufficiently investigated to cope with multiple opportunities in crop rotations.
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Heidemeyer, Peter. "ZSK-NT the New Two-Stage Processing System for High Throughputs." In Co-Rotating Twin-Screw Extruder, 289–301. München: Carl Hanser Verlag GmbH & Co. KG, 2007. http://dx.doi.org/10.3139/9783446433410.015.
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Weichert, Andreas, Christoph Riehn, and Bernhard Brutschy. "State-selective Rotational Coherence Spectroscopy by Two-color Pump-Probe Schemes." In Ultrafast Phenomena XII, 331–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56546-5_96.
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Shi, Qian, Yichen Yao, and Suyuan Yu. "The Design of the Robust Controller for Active Magnetic Bearings on Active Disturbance Rejection Technology." In Springer Proceedings in Physics, 1147–58. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1023-6_99.
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AbstractActive magnetic bearings (AMBs) have advantages of no friction, no lubrication or sealing requirements, long lifespan, low maintenance cost, and, especially, active controllability of dynamic characteristics. Thus, AMBs are now widely used in helium-turbine circle of the high temperature gas-cooled reactor and many other high-speed rotating machinery. The design of controller is the core problem of AMBs. The AMB force has high nonlinearity and the AMBs-rotor system may be influenced by external disturbance during operation, which increase the threshold of the controller robustness and make it hard to design. Based on the AMB-rigid rotor system model, this paper adopts lumped uncertainties to describe nonlinear error and external load disturbance and then the plant model of the decentralized controller is obtained. Then, a linear active disturbance rejection controller (LADRC) is designed to compensate the model error. The LADRC contains a proportional-differential controller and a three-order external state observer. The adjustable parameters of the LADRC can be selected according to pole assignment. In order to verify the effectiveness of the LADRC, levitation experiments, rotation experiments, and re-levitation experiments are carried out with traditional PID controller as comparison.
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Johnson, R. D., C. S. Yannoni, H. C. Dorn, J. R. Salem, and D. S. Bethune. "C60 Rotational Dynamics in the Solid State." In Physics and Chemistry of Finite Systems: From Clusters to Crystals, 1329–34. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-017-2645-0_184.
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Linß, Sebastian, Philipp Gräser, Mario Torres, Tobias Kaletsch, René Theska, and Lena Zentner. "A Novel Planar Two-Axis Leaf-Type Notch Flexure Hinge with Coincident Rotation Axes and Its Application to Micropositioning Stages." In Microactuators, Microsensors and Micromechanisms, 1–14. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-61652-6_1.
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Molendijk, Leendert P. G., and Richard A. Sikora. "Decision support systems in integrated nematode management: the need for a holistic approach." In Integrated nematode management: state-of-the-art and visions for the future, 428–38. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247541.0060.
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Abstract Farmers' decisions regarding the best approach to take in managing a nematode problem are often made just before the planting season begins and then at different stages in crop growth. In many cases an integrated nematode management (INM) system with multiple components is not considered due to lack of knowledge of the severity of the nematode problem, or the absence of an acceptable management tool such as a suitable resistant or tolerant cultivar, an appropriate non-host rotation crop or a suitable biocide for the situation. Seldom, if ever, are data on nematode population densities and distribution patterns across a field taken into consideration in the decision making process. This haphazard approach to INM is comparable to what could be called a 'take a chance' or 'shot in the dark' tactic which often results from the absence of effective decision support tools (DST) or decision support systems (DSS). This chapter discusses presently available information on different forms of DST and DSS as well as the developments that are required to streamline and improve INM.
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Eliseev, Alexander A., Tatiana A. Kalashnikova, Andrey V. Filippov, and Evgeny A. Kolubaev. "Material Transfer by Friction Stir Processing." In Springer Tracts in Mechanical Engineering, 169–88. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-60124-9_8.
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AbstractMechanical surface hardening processes have long been of interest to science and technology. Today, surface modification technologies have reached a new level. One of them is friction stir processing that refines the grain structure of the material to a submicrocrystalline state. Previously, the severe plastic deformation occurring during processing was mainly described from the standpoint of temperature and deformation, because the process is primarily thermomechanical. Modeling of friction stir welding and processing predicted well the heat generation in a quasi-liquid medium. However, the friction stir process takes place in the solid phase, and therefore the mass transfer issues remained unresolved. The present work develops the concept of adhesive-cohesive mass transfer during which the rotating tool entrains the material due to adhesion, builds up a transfer layer due to cohesion, and then leaves it behind. Thus, the transfer layer thickness is a clear criterion for the mass transfer effectiveness. Here we investigate the effect of the load on the transfer layer and analyze it from the viewpoint of the friction coefficient and heat generation. It is shown that the transfer layer thickness increases with increasing load, reaches a maximum, and then decreases. In so doing, the average moment on the tool and the temperature constantly grow, while the friction coefficient decreases. This means that the mass transfer cannot be fully described in terms of temperature and strain. The given load dependence of the transfer layer thickness is explained by an increase in the cohesion forces with increasing load, and then by a decrease in cohesion due to material overheating. The maximum transfer layer thickness is equal to the feed to rotation rate ratio and is observed at the axial load that causes a stress close to the yield point of the material. Additional plasticization of the material resulting from the acoustoplastic effect induced by ultrasonic treatment slightly reduces the transfer layer thickness, but has almost no effect on the moment, friction coefficient, and temperature. The surface roughness of the processed material is found to have a similar load dependence.
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Augustin, Bernd. "The need for new approaches for management of potato cyst nematodes: the view from the Rhineland-Palatinate." In Integrated nematode management: state-of-the-art and visions for the future, 319–26. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247541.0044.
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Abstract Potato is an important crop throughout Europe and especially in Germany where potatoes are grown on over 250,000 hectares. The production of potato worldwide is negatively affected by the presence of the golden and the white potato cyst nematodes (PCN) Globodera rostochiensis and G. pallida. The two species originated in South America. PCN is present with restricted distribution in all counties in Germany where potato is produced and these infestations are strictly regulated. Both species are present and often in mixed populations. Potato yield and overall production is negatively impacted by both species of PCN from planting to harvest, but there are differences in importance within the country and on crop type. This chapter discusses the economic importance, host range, distribution, symptoms of damage, biology and life cycle, integrated nematode management (including the use of nematicides, resistant cultivars and rotation), and interactions with other nematodes and pathogens, of PCN. Results are also summarized of field trials conducted between 2010 and 2017 to compare the efficacy of resistant cultivars and nematicide Nemathorin 10G with the alternative control techniques biofumigation and sowing of Solanum sisymbriifolium that has PCN suppressive activity.
Conference papers on the topic "Two stage rotation"
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Rheem, Chang-Kyu. "Investigation of the 2D Behavior of a Rotating Cylinder in Flow Using the Discrete Vortex Method." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95841.
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Abstract The influence of rotation on the behavior of a two-dimensional rotating cylinder in flow was investigated by using the discrete vortex method combined with the 4th order Runge-Kutta method. There are three stages for rotational speed dependence of hydrodynamic force on a fixed rotating cylinder, the stage where lift force increases and drag force decreases, the stage where lift and drag forces increase in proportion to the square of rotation ratio, and the stage where lift and drag forces increase in proportion to rotation ratio. As a fixed rotating cylinder begins to rotate and the rotational speed increases, the vortex train that causes VIV weakens and disappears. When the cylinder is mounted on a spring, the vibration frequency of the spring mounted rotating cylinder becomes lower. This indicates that the added mass of the rotating cylinder is increasing as the rotation ratio increases.
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Lee, Wen-Chia, and Chin-Hsing Chen. "A Fast Template Matching Method for Rotation Invariance Using Two-Stage Process." In 2009 Fifth International Conference on Intelligent Information Hiding and Multimedia Signal Processing (IIH-MSP). IEEE, 2009. http://dx.doi.org/10.1109/iih-msp.2009.208.
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Li, Zhe, Lianwen Jin, and Songxuan Lai. "Rotation-Free Online Handwritten Chinese Character Recognition using Two-Stage Convolutional Neural Network." In 2018 16th International Conference on Frontiers in Handwriting Recognition (ICFHR). IEEE, 2018. http://dx.doi.org/10.1109/icfhr-2018.2018.00044.
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Scano, Lorenzo, and Gianmario L. Arnulfi. "Rotating Stall Model and Simulation of Two-Stage Centrifugal Compressors." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27922.
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Often turbo-compressors exhibit the maximum efficiency condition very close to the stall limit, so that it would be highly interesting to have a deep comprehension of this phenomenon. Despite the large diffusion of the multi-stage centrifugal compressors in different fields of the technology, such as natural gas pipe-lines or chemical factories, at the best authors’ knowledge, to date no theoretical model exists for rotating stall in these machines. This paper deals with a model for simulating multi-stage centrifugal compressor flow pattern during rotating stall. The model is not able to capture the stall inception, so the velocity and pressure fields are calculated throughout the machine once rotating stall has developed. The model consists of an implementation of that proposed by Moore for single-stage centrifugal compressors, so the simplifying hypotheses are: irrotational upstream fluid flow, inviscid and incompressible flow, stationary flow in the frame rotating at the same frequency of the stall cell; infinite blades are supposed both in rotors and return channel. Even if these fluid-dynamic hypotheses are really strong, it is worth of note that the reference models for rotating stall simulation in turbo-compressors (namely the Moore’s models) are based, at the present time, on them. In a previous step of this research, the authors utilized a semi-empirical approach, with phases changes between first and second diffuser based on experimental data. Now this hypothesis is removed and the model is fully analytical. The mathematical model is solved by numerical way, leaving the original semi-analytical scheme of Moore, so allowing the stall cell propagation frequency to be calculated. The computer code is written in C language for Linux operating system. It was tested in single-stage configuration with results according to Moore’s theory; for two-stage setup, obtained results appear consistent and qualitatively according with experimental tests and, unlike the single stage analysis, only fast rotation waves were found.
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Li, Xiaoli, Yang Yang, Wentao Yang, Guobin Zhang, Wenting Cui, and Shaoyi Du. "Pamls Alignment Based On Two-Stage Convolutional Network with a Large in-Plane Rotation." In 2020 IEEE International Conference on Systems, Man, and Cybernetics (SMC). IEEE, 2020. http://dx.doi.org/10.1109/smc42975.2020.9283186.
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Ravichandran, A., and B. Yegnanarayana. "A two-stage neural network for translation, rotation and size-invariant visual pattern recognition." In [Proceedings] ICASSP 91: 1991 International Conference on Acoustics, Speech, and Signal Processing. IEEE, 1991. http://dx.doi.org/10.1109/icassp.1991.150874.
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Sharma, P. B., and A. Adekoya. "A Review of Recent Research on Contra-Rotating Axial Flow Compressor Stage." In ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-254.
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Aero compressor technology has seen a significant advancement during the last two decades. Research on Rotor-Stator stage has focused on improvements in the design as well as off-design performance. Work has also been carried out to improve the clearance losses, stage loading as well as the stability of the operation. In this connection, the work on end-bend rotor-stator and variable geometry stators is specially significant. These efforts have however, yielded marginal improvements as far as the capability of the stage to produce pressure rise and its through-flow capacity are concerned. The interest in contra-rotation has emerged with a view to achieve considerable high pressure rise per stage besides its effects on stability of the stage to rotating stall/surge suppression. Contra-rotation concept has already found its acceptability in the development of future fuel efficient gas turbine plants and aero engines. This paper presents a review of the experimental and theoretical investigations on the aero-dynamic and aero-acoustic performance of the contra-rotating pressure stage. The areas of future work on contra-rotation are also outlined.
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Liu, Wei, Yunbo Yuan, Tao He, and Donghua Wang. "Free Vibration Analysis of Two-Stage Planetary Gear With Friction." In ASME 2018 Noise Control and Acoustics Division Session presented at INTERNOISE 2018. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/ncad2018-6133.
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Considering the effect of teeth surface sliding friction, free vibration of two-stage planetary gears (TPG) is studied theoretically for the first time. The lateral-torsional coupling dynamic model and equation are established with three degrees of freedom: two translations and one rotation. The change rule of natural frequency is discussed with the case of first stage planetary gear’s number 4 and second stage planetary gear’s number 3, 4 and 5. Afterwards three vibration modes are summarized by calculating the free vibration. In order to understand the behavior of friction, the effect of friction on natural frequencies is analyzed for the case of considering friction and not considering friction. Furthermore, the ‘self-coupling’ phenomenon is obtained from the vibration of center component of TPG Meanwhile, the ‘mutual coupling’ is obtained between the first-stage planetary gear (FPG) and the second-stage planetary gear (SPG).
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Verhulst, Tedja, Eddie Yin-Kwee Ng, Yongmann Chung, David Judt, and Craig Lawson. "Predicting Cavitation Erosion on Two-Stage Pumps Using CFD." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-84165.
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Abstract Cavitation is a common problem that occurs in pumps which reduces its useful life and bring increased operating costs to the user. A study of cavitation erosion on a two-stage centrifugal pump has been carried out using Computational Fluid Dynamics (CFD). Most cavitation studies on pumps have been focused on modelling the severity of cavitation; specifically, on understanding its visual effects and performance penalties. Few works have been carried out to predict the most erosion-sensitive areas inside a pump. The focus of this study is on modelling the permanent damage that would be caused by cavitation and to identify specific areas within the pump which are most susceptible to erosion. The model is first validated against experimental data from another work. Once the simulation has been successfully calibrated, the cavitation simulation is carried out again with the subject pump. Not only does this work extend the findings previous works by predicting cavitation erosion on a two-stage pump, but the pump rotation speed is also varied to observe how the erosion-sensitive areas on the pump changes as a result. A specific focus on the Gray Level Method is carried out to predict the erosion damage on the pump. This technique is chosen as it has been experimentally proven with single-stage radial pumps, using specialized CFD code. It is found that the algorithm used to predict erosion when applied with commercial CFD packages, are useful in distinguishing areas inside the pump which are most vulnerable to erosion damage. The Scherr-Sauer cavitation model coupled with the κ-ω SST turbulence model have been used to run the cavitation simulations.
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Wang, Songtao, and Zhongqi Wang. "The Tip and Hub Leakage Flow of a Repeated Two Stage Compressor." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30437.
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End wall flow of a repeated two stage compressor at design and choke condition were studied by numerical simulation. The vortex near the hub depends on the traverse pressure gradient and sheer force induced by the hub rotation. At the design and the choke condition the hub leakage vortex is the dominant secondary flow. The position and trajectory of the tip leakage vortex at design and choke condition were also studied. At the design condition the tip leakage vortex traverse the blade channel and impinge on the middle chord of the suction surface of the adjacent blade. At the near choke condition the tip leakage vortex would go downstream along the streamwise direction. The composition of the tip vortex was also studied. It is clearly to distinguish the strong and weak part of the tip leakage vortex for design condition while at the near choke condition there is no evident weak part of the tip leakage vortex.
Reports on the topic "Two stage rotation"
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Muralikrishnan, Bala, Prashanth Jaganmoha, Meghan Shilling, and Ed Morse. Sensitivity to X-Ray Computed Tomography Instrument Geometry Errors as a Function of Rotation Stage Position, Detector Position, and Detector Size. National Institute of Standards and Technology, September 2021. http://dx.doi.org/10.6028/nist.ir.8393.
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Perkins, Dustin. Invasive exotic plant monitoring in Capitol Reef National Park: 2020 and 2021 field seasons. National Park Service, August 2022. http://dx.doi.org/10.36967/2294094.
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Invasive exotic plant (IEP) species are a significant threat to natural ecosystem integrity and biodiversity. Controlling them is a high priority for the National Park Service. The Northern Colorado Plateau Network (NCPN) selected the early detection of IEPs as one of 11 moni-toring protocols to be implemented as part of its long-term monitoring program. From June 5 to July 29, 2020, and May 30 to June 2, 2021, network staff conducted surveys for priority IEP species along the Oak Creek, Pleasant Creek, and State Route 24 monitoring routes at Capitol Reef National Park. We detected 834 patches of 11 priority IEP species along 67.9 kilometers (42.2 miles) of three monitoring routes. There were more patches of tamarisk along State Route 24, and a higher percentage of large patches, than in previous years. This indicates that previously identified IEP patches have expanded and grown. Field bindweed (Convolvulus arvensis) and Russian olive (Elaeagnus angustifolia) along State Route 24 have both increased in prevalence since monitoring began. Tamarisk (Tamarix sp.) was the most prevalent prior-ity IEP species on all three routes. On Oak and Pleasant creeks, there were fewer than three patches of all other IEPs. On State Route 24, there were 30 or more patches of Russian olive, quackgrass (Elymus repens), field bindweed, and blue mustard (Chorispora tenella). IEP prior-ity species were found on 71%, 47%, and 62% of transects along Oak Creek, Pleasant Creek, and State Route 24, respectively. Yellow sweet-clover (Melilotus officinalis) was the most fre-quently observed IEP on Oak Creek and Pleasant Creek. Percent cover was highest for yellow sweet-clover, Russian thistle (Salsola sp.), and tamarisk on Oak Creek, Pleasant Creek, and State Route 24, respectively. The NCPN plans to return to Capitol Reef in 2023 to continue the fourth rotation of invasive plant monitoring.
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Seginer, Ido, Louis D. Albright, and Robert W. Langhans. On-line Fault Detection and Diagnosis for Greenhouse Environmental Control. United States Department of Agriculture, February 2001. http://dx.doi.org/10.32747/2001.7575271.bard.
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Background Early detection and identification of faulty greenhouse operation is essential, if losses are to be minimized by taking immediate corrective actions. Automatic detection and identification would also free the greenhouse manager to tend to his other business. Original objectives The general objective was to develop a method, or methods, for the detection, identification and accommodation of faults in the greenhouse. More specific objectives were as follows: 1. Develop accurate systems models, which will enable the detection of small deviations from normal behavior (of sensors, control, structure and crop). 2. Using these models, develop algorithms for an early detection of deviations from the normal. 3. Develop identifying procedures for the most important faults. 4. Develop accommodation procedures while awaiting a repair. The Technion team focused on the shoot environment and the Cornell University team focused on the root environment. Achievements Models: Accurate models were developed for both shoot and root environment in the greenhouse, utilizing neural networks, sometimes combined with robust physical models (hybrid models). Suitable adaptation methods were also successfully developed. The accuracy was sufficient to allow detection of frequently occurring sensor and equipment faults from common measurements. A large data base, covering a wide range of weather conditions, is required for best results. This data base can be created from in-situ routine measurements. Detection and isolation: A robust detection and isolation (formerly referred to as 'identification') method has been developed, which is capable of separating the effect of faults from model inaccuracies and disturbance effects. Sensor and equipment faults: Good detection capabilities have been demonstrated for sensor and equipment failures in both the shoot and root environment. Water stress detection: An excitation method of the shoot environment has been developed, which successfully detected water stress, as soon as the transpiration rate dropped from its normal level. Due to unavailability of suitable monitoring equipment for the root environment, crop faults could not be detected from measurements in the root zone. Dust: The effect of screen clogging by dust has been quantified. Implications Sensor and equipment fault detection and isolation is at a stage where it could be introduced into well equipped and maintained commercial greenhouses on a trial basis. Detection of crop problems requires further work. Dr. Peleg was primarily responsible for developing and implementing the innovative data analysis tools. The cooperation was particularly enhanced by Dr. Peleg's three summer sabbaticals at the ARS, Northem Plains Agricultural Research Laboratory, in Sidney, Montana. Switching from multi-band to hyperspectral remote sensing technology during the last 2 years of the project was advantageous by expanding the scope of detected plant growth attributes e.g. Yield, Leaf Nitrate, Biomass and Sugar Content of sugar beets. However, it disrupted the continuity of the project which was originally planned on a 2 year crop rotation cycle of sugar beets and multiple crops (com and wheat), as commonly planted in eastern Montana. Consequently, at the end of the second year we submitted a continuation BARD proposal which was turned down for funding. This severely hampered our ability to validate our findings as originally planned in a 4-year crop rotation cycle. Thankfully, BARD consented to our request for a one year extension of the project without additional funding. This enabled us to develop most of the methodology for implementing and running the hyperspectral remote sensing system and develop the new analytical tools for solving the non-repeatability problem and analyzing the huge hyperspectral image cube datasets. However, without validation of these tools over a ful14-year crop rotation cycle this project shall remain essentially unfinished. Should the findings of this report prompt the BARD management to encourage us to resubmit our continuation research proposal, we shall be happy to do so.
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Weissinger, Rebecca. Trends in water quality at Bryce Canyon National Park, water years 2006–2021. Edited by Alice Wondrak Biel. National Park Service, November 2022. http://dx.doi.org/10.36967/2294946.
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The National Park Service collects water-quality samples on a rotating basis at three fixed water-quality stations in Bryce Canyon National Park (NP): Sheep Creek, Yellow Creek, and Mossy Cave Spring. Data collection began at Sheep Creek and Yellow Creek in November 2005 and at Mossy Cave in July 2008. Data on in-situ parameters, fecal-coliform samples, major ions, and nutrients are collected monthly, while trace elements are sampled quarterly. This report analyzes data from the beginning of the period of record for each station through water year 2021 to test for trends over time. Concentrations are also compared to relevant water-quality standards for the State of Utah. Overall, water quality at the park’s monitoring stations continues to be excellent, and park managers have been successful in their goal of maintaining these systems in unimpaired condition. Infrequent but continued Escherichia coli exceedances from trespass livestock at Sheep and Yellow creeks support the need for regular fence maintenance along the park boundary. High-quality conditions may qualify all three sites as Category 1 waters, the highest level of anti-degradation protection provided by the State of Utah. Minimum and maximum air temperatures at the park have increased, while precipitation remains highly variable. Increasing air temperatures have led to increasing water temperatures in Sheep and Yellow creeks. Sheep Creek also had a decrease in flow across several quantiles from 2006 to 2021, while higher flows decreased at Yellow Creek in the same period. Surface flows in these two creeks are likely to be increasingly affected by higher evapotranspiration due to warming air temperatures and possibly decreasing snowmelt runoff as the climate changes. The influx of ancient groundwater in both creek drainages helps sustain base flows at the sites. Mossy Cave Spring, which is sampled close to the spring emergence point, showed less of a climate signal than Sheep and Yellow creeks. In our record, the spring shows a modest increase in discharge, including higher flows at higher air temperatures. An uptick in visitation to Water Canyon and the Mossy Cave Trail has so far not been reflected by changes in water quality. There are additional statistical trends in water-quality parameters at all three sites. However, most of these trends are quite small and are likely ecologically negligible. Some statistical trends may be the result of instrument changes and improvements in quality assurance and quality control over time in both the field sampling effort and the laboratory analyses. Long-term monitoring of water-quality stations at Bryce Canyon NP suggests relatively stable aquatic systems that benefit from protection within the park. To maintain these unimpaired conditions into the future, park managers could consider: Regular fence checks and maintenance along active grazing allotments at the park boundary to protect riparian areas and aquatic systems from trespass livestock. Developing a springs-monitoring program to track changes in springflow at spring emergences to better understand bedrock-aquifer water supplies. These data would also help quantify springflow for use in water-rights hearings. Supporting hydrogeologic investigations to map the extent and flow paths of groundwater aquifers. Working with the State of Utah to develop groundwater-protection zones to protect groundwater aquifers from developments that would affect springs in the park. Prioritizing watershed management with proactive fire risk-reduction practices. Explicitly including watershed protection as a goal in plans for fire management and suppression. Using additional data and analyses to better understand the drivers of trends in water quality and their ecological significance. These could include higher-frequency data to better understand relationships between groundwater, precipitation, and surface flows at the sites. These could also include watershed metrics...
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MOMENT-ROTATION MODEL OF EXTERNAL COVER PLATE JOINTS BETWEEN STEEL BEAMS AND CONCRETE-FILLED SQUARE STEEL TUBULAR COLUMNS WITH INNER I-SHAPED CFRP PROFILE. The Hong Kong Institute of Steel Construction, June 2023. http://dx.doi.org/10.18057/ijasc.2023.19.2.5.
Full textAbstract:
As a new type of beam-column joint, external cover plate joints can be used in concrete-filled square steel tubular (CFSST) structures. To accurately analyze the mechanical characteristics of this novel joint during structural design, it is necessary to investigate the moment-rotation relationships. Based on the analysis of the force-transferring mechanism, the formulas to decide the initial rotation stiffness and ultimate bending moment are founded by using the component analysis method, while the finite element analysis results are also utilized to verify these formulas. Considering the advantages and disadvantages of the existing typical moment-rotation models, a new representation for calculating the moment-rotation curve of the external cover plate joints is proposed using the ultimate bending moment and initial rotation stiffness as two basic parameters. The research reveals that the moment-rotation model proposed in this paper is able to take all loading stages of this joint into account, which facilitates the analysis of yield and ultimate loads. In addition, this model is smooth and continuous at the piecewise points to avoid numerical problems that may be caused in the calculation. Comparing the moment-rotation curves obtained by the calculation model and finite element simulation, the results show good consistency, demonstrating that the moment-rotation model presented in this paper is applicable to the analysis and design of the external cover plate joints.
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Coastal Lidar And Radar Imaging System (CLARIS) mobile terrestrial lidar survey along the Outer Banks, North Carolina in Currituck and Dare counties. Coastal and Hydraulics Laboratory (U.S.), January 2020. http://dx.doi.org/10.21079/11681/39419.
Full textAbstract:
The Coastal Observation and Analysis Branch (COAB) located at the Field Research Facility (FRF) conducts quarterly surveys and post-storm surveys along up to 60 kilometers of coastline within the vicinity of the FRF to assess, evaluate, and provide updated observations of the morphology of the foreshore and dune system. The surveys are conducted using a mobile terrestrial LiDAR scanner coupled with an Inertial Navigation System (INS). Traditionally the surveys coincide with a low tide, exposing the widest swath of visible sediment to the scanner as well as enough wind-sea swell or texture to induce wave breaking upon the interior sandbars. The wave field is measured with X-Band radar which records a spatial time series of wave direction and speed. Data for the survey region was collected using the VZ-2000's mobile, 3D scanning mode where the scanner continuously rotates the line scan 360 degrees as the vehicle progresses forward. Elevation measurements are acquired on all sides of the vehicle except for the topography directly underneath the vehicle. As the vehicle moves forward, the next rotation will capture the previous position's occluded data area. Laser data is acquired in mobile 3D radar mode with a pulse repetition rate of 300kHz, theta resolution of 0.19 degrees and phi resolution of 0.625 degrees. Horizontal Datum NAD83(2011), Projection North Carolina State Plane (3200) meters; Vertical Datum NAVD88, meters with geoid09 applied.
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Coastal Lidar And Radar Imaging System (CLARIS) mobile terrestrial lidar survey along the Outer Banks, North Carolina in Currituck and Dare counties. Coastal and Hydraulics Laboratory (U.S.), January 2020. http://dx.doi.org/10.21079/11681/39419.
Full textAbstract:
The Coastal Observation and Analysis Branch (COAB) located at the Field Research Facility (FRF) conducts quarterly surveys and post-storm surveys along up to 60 kilometers of coastline within the vicinity of the FRF to assess, evaluate, and provide updated observations of the morphology of the foreshore and dune system. The surveys are conducted using a mobile terrestrial LiDAR scanner coupled with an Inertial Navigation System (INS). Traditionally the surveys coincide with a low tide, exposing the widest swath of visible sediment to the scanner as well as enough wind-sea swell or texture to induce wave breaking upon the interior sandbars. The wave field is measured with X-Band radar which records a spatial time series of wave direction and speed. Data for the survey region was collected using the VZ-2000's mobile, 3D scanning mode where the scanner continuously rotates the line scan 360 degrees as the vehicle progresses forward. Elevation measurements are acquired on all sides of the vehicle except for the topography directly underneath the vehicle. As the vehicle moves forward, the next rotation will capture the previous position's occluded data area. Laser data is acquired in mobile 3D radar mode with a pulse repetition rate of 300kHz, theta resolution of 0.19 degrees and phi resolution of 0.625 degrees. Horizontal Datum NAD83(2011), Projection North Carolina State Plane (3200) meters; Vertical Datum NAVD88, meters with geoid09 applied.
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Tire Experimental Characterization Using Contactless Measurement Methods. SAE International, August 2021. http://dx.doi.org/10.4271/2021-01-1114.
Full textAbstract:
In the frame of automotive Noise Vibration and Harshness (NVH) evaluation, inner cabin noise is among the most important indicators. The main noise contributors can be identified in engine, suspensions, tires, powertrain, brake system, etc. With the advent of E-vehicles and the consequent absence of the Internal Combustion Engine (ICE), tire/road noise has gained more importance, particularly at mid-speed driving and in the spectrum up to 300 Hz. At the state of the art, the identification and characterization of Noise and Vibration sources rely on pointwise sensors (microphones, accelerometers, strain gauges). Optical methods such as Digital Image Correlation (DIC) and Laser Doppler Vibrometer (LDV) have recently received special attention in the NVH field because they can be used to obtain full-field measurements. Moreover, these same techniques could also allow to characterize the tire behavior in operating conditions, which would be practically impossible to derive with standard techniques. In this paper we will demonstrate how non-contact full-field measurement techniques can be used to reliably and robustly characterize the tire behavior up to 300 Hz, focusing on static conditions. Experimental modal analysis will extract the modal characteristic of the tire in both free-free and statically preloaded boundary conditions, using both DIC and LDV. The extracted natural frequencies, damping ratios and full-field mode shapes will be used on one side to improve the accuracy of tire models (either by deriving FRF based models or updating FE ones) but also as a reference for future investigation on the tire behavior characterization in rotating conditions.